/* $NetBSD: pcap-linux.c,v 1.8 2024/09/02 15:33:37 christos Exp $ */
/*
* pcap-linux.c: Packet capture interface to the Linux kernel
*
* Copyright (c) 2000 Torsten Landschoff <
[email protected]>
* Sebastian Krahmer <
[email protected]>
*
* License: BSD
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* Modifications: Added PACKET_MMAP support
* Paolo Abeni <
[email protected]>
* Added TPACKET_V3 support
* Gabor Tatarka <
[email protected]>
*
* based on previous works of:
* Simon Patarin <
[email protected]>
* Phil Wood <
[email protected]>
*
* Monitor-mode support for mac80211 includes code taken from the iw
* command; the copyright notice for that code is
*
* Copyright (c) 2007, 2008 Johannes Berg
* Copyright (c) 2007 Andy Lutomirski
* Copyright (c) 2007 Mike Kershaw
* Copyright (c) 2008 Gábor Stefanik
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#define _GNU_SOURCE
#include <sys/cdefs.h>
__RCSID("$NetBSD: pcap-linux.c,v 1.8 2024/09/02 15:33:37 christos Exp $");
#include <config.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <limits.h>
#include <endian.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <sys/mman.h>
#include <linux/if.h>
#include <linux/if_packet.h>
#include <linux/sockios.h>
#include <linux/ethtool.h>
#include <netinet/in.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <poll.h>
#include <dirent.h>
#include <sys/eventfd.h>
#include "pcap-int.h"
#include "pcap-util.h"
#include "pcap/sll.h"
#include "pcap/vlan.h"
#include "pcap/can_socketcan.h"
#include "diag-control.h"
/*
* We require TPACKET_V2 support.
*/
#ifndef TPACKET2_HDRLEN
#error "Libpcap will only work if TPACKET_V2 is supported; you must build for a 2.6.27 or later kernel"
#endif
/* check for memory mapped access availability. We assume every needed
* struct is defined if the macro TPACKET_HDRLEN is defined, because it
* uses many ring related structs and macros */
#ifdef TPACKET3_HDRLEN
# define HAVE_TPACKET3
#endif /* TPACKET3_HDRLEN */
/*
* Not all compilers that are used to compile code to run on Linux have
* these builtins. For example, older versions of GCC don't, and at
* least some people are doing cross-builds for MIPS with older versions
* of GCC.
*/
#ifndef HAVE___ATOMIC_LOAD_N
#define __atomic_load_n(ptr, memory_model) (*(ptr))
#endif
#ifndef HAVE___ATOMIC_STORE_N
#define __atomic_store_n(ptr, val, memory_model) *(ptr) = (val)
#endif
#define packet_mmap_acquire(pkt) \
(__atomic_load_n(&pkt->tp_status, __ATOMIC_ACQUIRE) != TP_STATUS_KERNEL)
#define packet_mmap_release(pkt) \
(__atomic_store_n(&pkt->tp_status, TP_STATUS_KERNEL, __ATOMIC_RELEASE))
#define packet_mmap_v3_acquire(pkt) \
(__atomic_load_n(&pkt->hdr.bh1.block_status, __ATOMIC_ACQUIRE) != TP_STATUS_KERNEL)
#define packet_mmap_v3_release(pkt) \
(__atomic_store_n(&pkt->hdr.bh1.block_status, TP_STATUS_KERNEL, __ATOMIC_RELEASE))
#include <linux/types.h>
#include <linux/filter.h>
#ifdef HAVE_LINUX_NET_TSTAMP_H
#include <linux/net_tstamp.h>
#endif
/*
* For checking whether a device is a bonding device.
*/
#include <linux/if_bonding.h>
/*
* Got libnl?
*/
#ifdef HAVE_LIBNL
#include <linux/nl80211.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/family.h>
#include <netlink/genl/ctrl.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
#endif /* HAVE_LIBNL */
#ifndef HAVE_SOCKLEN_T
typedef int socklen_t;
#endif
#define MAX_LINKHEADER_SIZE 256
/*
* When capturing on all interfaces we use this as the buffer size.
* Should be bigger then all MTUs that occur in real life.
* 64kB should be enough for now.
*/
#define BIGGER_THAN_ALL_MTUS (64*1024)
/*
* Private data for capturing on Linux PF_PACKET sockets.
*/
struct pcap_linux {
long long sysfs_dropped; /* packets reported dropped by /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors */
struct pcap_stat stat;
char *device; /* device name */
int filter_in_userland; /* must filter in userland */
int blocks_to_filter_in_userland;
int must_do_on_close; /* stuff we must do when we close */
int timeout; /* timeout for buffering */
int cooked; /* using SOCK_DGRAM rather than SOCK_RAW */
int ifindex; /* interface index of device we're bound to */
int lo_ifindex; /* interface index of the loopback device */
int netdown; /* we got an ENETDOWN and haven't resolved it */
bpf_u_int32 oldmode; /* mode to restore when turning monitor mode off */
char *mondevice; /* mac80211 monitor device we created */
u_char *mmapbuf; /* memory-mapped region pointer */
size_t mmapbuflen; /* size of region */
int vlan_offset; /* offset at which to insert vlan tags; if -1, don't insert */
u_int tp_version; /* version of tpacket_hdr for mmaped ring */
u_int tp_hdrlen; /* hdrlen of tpacket_hdr for mmaped ring */
u_char *oneshot_buffer; /* buffer for copy of packet */
int poll_timeout; /* timeout to use in poll() */
#ifdef HAVE_TPACKET3
unsigned char *current_packet; /* Current packet within the TPACKET_V3 block. Move to next block if NULL. */
int packets_left; /* Unhandled packets left within the block from previous call to pcap_read_linux_mmap_v3 in case of TPACKET_V3. */
#endif
int poll_breakloop_fd; /* fd to an eventfd to break from blocking operations */
};
/*
* Stuff to do when we close.
*/
#define MUST_CLEAR_RFMON 0x00000001 /* clear rfmon (monitor) mode */
#define MUST_DELETE_MONIF 0x00000002 /* delete monitor-mode interface */
/*
* Prototypes for internal functions and methods.
*/
static int get_if_flags(const char *, bpf_u_int32 *, char *);
static int is_wifi(const char *);
static int map_arphrd_to_dlt(pcap_t *, int, const char *, int);
static int pcap_activate_linux(pcap_t *);
static int setup_socket(pcap_t *, int);
static int setup_mmapped(pcap_t *);
static int pcap_can_set_rfmon_linux(pcap_t *);
static int pcap_inject_linux(pcap_t *, const void *, int);
static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
static int pcap_set_datalink_linux(pcap_t *, int);
static void pcap_cleanup_linux(pcap_t *);
union thdr {
struct tpacket2_hdr *h2;
#ifdef HAVE_TPACKET3
struct tpacket_block_desc *h3;
#endif
u_char *raw;
};
#define RING_GET_FRAME_AT(h, offset) (((u_char **)h->buffer)[(offset)])
#define RING_GET_CURRENT_FRAME(h) RING_GET_FRAME_AT(h, h->offset)
static void destroy_ring(pcap_t *handle);
static int create_ring(pcap_t *handle);
static int prepare_tpacket_socket(pcap_t *handle);
static int pcap_read_linux_mmap_v2(pcap_t *, int, pcap_handler , u_char *);
#ifdef HAVE_TPACKET3
static int pcap_read_linux_mmap_v3(pcap_t *, int, pcap_handler , u_char *);
#endif
static int pcap_setnonblock_linux(pcap_t *p, int nonblock);
static int pcap_getnonblock_linux(pcap_t *p);
static void pcapint_oneshot_linux(u_char *user, const struct pcap_pkthdr *h,
const u_char *bytes);
/*
* In pre-3.0 kernels, the tp_vlan_tci field is set to whatever the
* vlan_tci field in the skbuff is. 0 can either mean "not on a VLAN"
* or "on VLAN 0". There is no flag set in the tp_status field to
* distinguish between them.
*
* In 3.0 and later kernels, if there's a VLAN tag present, the tp_vlan_tci
* field is set to the VLAN tag, and the TP_STATUS_VLAN_VALID flag is set
* in the tp_status field, otherwise the tp_vlan_tci field is set to 0 and
* the TP_STATUS_VLAN_VALID flag isn't set in the tp_status field.
*
* With a pre-3.0 kernel, we cannot distinguish between packets with no
* VLAN tag and packets on VLAN 0, so we will mishandle some packets, and
* there's nothing we can do about that.
*
* So, on those systems, which never set the TP_STATUS_VLAN_VALID flag, we
* continue the behavior of earlier libpcaps, wherein we treated packets
* with a VLAN tag of 0 as being packets without a VLAN tag rather than packets
* on VLAN 0. We do this by treating packets with a tp_vlan_tci of 0 and
* with the TP_STATUS_VLAN_VALID flag not set in tp_status as not having
* VLAN tags. This does the right thing on 3.0 and later kernels, and
* continues the old unfixably-imperfect behavior on pre-3.0 kernels.
*
* If TP_STATUS_VLAN_VALID isn't defined, we test it as the 0x10 bit; it
* has that value in 3.0 and later kernels.
*/
#ifdef TP_STATUS_VLAN_VALID
#define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & TP_STATUS_VLAN_VALID))
#else
/*
* This is being compiled on a system that lacks TP_STATUS_VLAN_VALID,
* so we test with the value it has in the 3.0 and later kernels, so
* we can test it if we're running on a system that has it. (If we're
* running on a system that doesn't have it, it won't be set in the
* tp_status field, so the tests of it will always fail; that means
* we behave the way we did before we introduced this macro.)
*/
#define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & 0x10))
#endif
#ifdef TP_STATUS_VLAN_TPID_VALID
# define VLAN_TPID(hdr, hv) (((hv)->tp_vlan_tpid || ((hdr)->tp_status & TP_STATUS_VLAN_TPID_VALID)) ? (hv)->tp_vlan_tpid : ETH_P_8021Q)
#else
# define VLAN_TPID(hdr, hv) ETH_P_8021Q
#endif
/*
* Required select timeout if we're polling for an "interface disappeared"
* indication - 1 millisecond.
*/
static const struct timeval netdown_timeout = {
0, 1000 /* 1000 microseconds = 1 millisecond */
};
/*
* Wrap some ioctl calls
*/
static int iface_get_id(int fd, const char *device, char *ebuf);
static int iface_get_mtu(int fd, const char *device, char *ebuf);
static int iface_get_arptype(int fd, const char *device, char *ebuf);
static int iface_bind(int fd, int ifindex, char *ebuf, int protocol);
static int enter_rfmon_mode(pcap_t *handle, int sock_fd,
const char *device);
static int iface_get_ts_types(const char *device, pcap_t *handle,
char *ebuf);
static int iface_get_offload(pcap_t *handle);
static int fix_program(pcap_t *handle, struct sock_fprog *fcode);
static int fix_offset(pcap_t *handle, struct bpf_insn *p);
static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
static int reset_kernel_filter(pcap_t *handle);
static struct sock_filter total_insn
= BPF_STMT(BPF_RET | BPF_K, 0);
static struct sock_fprog total_fcode
= { 1, &total_insn };
static int iface_dsa_get_proto_info(const char *device, pcap_t *handle);
pcap_t *
pcapint_create_interface(const char *device, char *ebuf)
{
pcap_t *handle;
handle = PCAP_CREATE_COMMON(ebuf, struct pcap_linux);
if (handle == NULL)
return NULL;
handle->activate_op = pcap_activate_linux;
handle->can_set_rfmon_op = pcap_can_set_rfmon_linux;
/*
* See what time stamp types we support.
*/
if (iface_get_ts_types(device, handle, ebuf) == -1) {
pcap_close(handle);
return NULL;
}
/*
* We claim that we support microsecond and nanosecond time
* stamps.
*
* XXX - with adapter-supplied time stamps, can we choose
* microsecond or nanosecond time stamps on arbitrary
* adapters?
*/
handle->tstamp_precision_list = malloc(2 * sizeof(u_int));
if (handle->tstamp_precision_list == NULL) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
pcap_close(handle);
return NULL;
}
handle->tstamp_precision_list[0] = PCAP_TSTAMP_PRECISION_MICRO;
handle->tstamp_precision_list[1] = PCAP_TSTAMP_PRECISION_NANO;
handle->tstamp_precision_count = 2;
/*
* Start out with the breakloop handle not open; we don't
* need it until we're activated and ready to capture.
*/
struct pcap_linux *handlep = handle->priv;
handlep->poll_breakloop_fd = -1;
return handle;
}
#ifdef HAVE_LIBNL
/*
* If interface {if_name} is a mac80211 driver, the file
* /sys/class/net/{if_name}/phy80211 is a symlink to
* /sys/class/ieee80211/{phydev_name}, for some {phydev_name}.
*
* On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
* least, has a "wmaster0" device and a "wlan0" device; the
* latter is the one with the IP address. Both show up in
* "tcpdump -D" output. Capturing on the wmaster0 device
* captures with 802.11 headers.
*
* airmon-ng searches through /sys/class/net for devices named
* monN, starting with mon0; as soon as one *doesn't* exist,
* it chooses that as the monitor device name. If the "iw"
* command exists, it does
*
* iw dev {if_name} interface add {monif_name} type monitor
*
* where {monif_name} is the monitor device. It then (sigh) sleeps
* .1 second, and then configures the device up. Otherwise, if
* /sys/class/ieee80211/{phydev_name}/add_iface is a file, it writes
* {mondev_name}, without a newline, to that file, and again (sigh)
* sleeps .1 second, and then iwconfig's that device into monitor
* mode and configures it up. Otherwise, you can't do monitor mode.
*
* All these devices are "glued" together by having the
* /sys/class/net/{if_name}/phy80211 links pointing to the same
* place, so, given a wmaster, wlan, or mon device, you can
* find the other devices by looking for devices with
* the same phy80211 link.
*
* To turn monitor mode off, delete the monitor interface,
* either with
*
* iw dev {monif_name} interface del
*
* or by sending {monif_name}, with no NL, down
* /sys/class/ieee80211/{phydev_name}/remove_iface
*
* Note: if you try to create a monitor device named "monN", and
* there's already a "monN" device, it fails, as least with
* the netlink interface (which is what iw uses), with a return
* value of -ENFILE. (Return values are negative errnos.) We
* could probably use that to find an unused device.
*
* Yes, you can have multiple monitor devices for a given
* physical device.
*/
/*
* Is this a mac80211 device? If so, fill in the physical device path and
* return 1; if not, return 0. On an error, fill in handle->errbuf and
* return PCAP_ERROR.
*/
static int
get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path,
size_t phydev_max_pathlen)
{
char *pathstr;
ssize_t bytes_read;
/*
* Generate the path string for the symlink to the physical device.
*/
if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't generate path name string for /sys/class/net device",
device);
return PCAP_ERROR;
}
bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen);
if (bytes_read == -1) {
if (errno == ENOENT || errno == EINVAL) {
/*
* Doesn't exist, or not a symlink; assume that
* means it's not a mac80211 device.
*/
free(pathstr);
return 0;
}
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s: Can't readlink %s", device, pathstr);
free(pathstr);
return PCAP_ERROR;
}
free(pathstr);
phydev_path[bytes_read] = '\0';
return 1;
}
struct nl80211_state {
struct nl_sock *nl_sock;
struct nl_cache *nl_cache;
struct genl_family *nl80211;
};
static int
nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device)
{
int err;
state->nl_sock = nl_socket_alloc();
if (!state->nl_sock) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink handle", device);
return PCAP_ERROR;
}
if (genl_connect(state->nl_sock)) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to connect to generic netlink", device);
goto out_handle_destroy;
}
err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache);
if (err < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate generic netlink cache: %s",
device, nl_geterror(-err));
goto out_handle_destroy;
}
state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
if (!state->nl80211) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl80211 not found", device);
goto out_cache_free;
}
return 0;
out_cache_free:
nl_cache_free(state->nl_cache);
out_handle_destroy:
nl_socket_free(state->nl_sock);
return PCAP_ERROR;
}
static void
nl80211_cleanup(struct nl80211_state *state)
{
genl_family_put(state->nl80211);
nl_cache_free(state->nl_cache);
nl_socket_free(state->nl_sock);
}
static int
del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice);
static int
add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice)
{
struct pcap_linux *handlep = handle->priv;
int ifindex;
struct nl_msg *msg;
int err;
ifindex = iface_get_id(sock_fd, device, handle->errbuf);
if (ifindex == -1)
return PCAP_ERROR;
msg = nlmsg_alloc();
if (!msg) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink msg", device);
return PCAP_ERROR;
}
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
0, NL80211_CMD_NEW_INTERFACE, 0);
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
DIAG_OFF_NARROWING
NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice);
DIAG_ON_NARROWING
NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);
err = nl_send_auto_complete(state->nl_sock, msg);
if (err < 0) {
if (err == -NLE_FAILURE) {
/*
* Device not available; our caller should just
* keep trying. (libnl 2.x maps ENFILE to
* NLE_FAILURE; it can also map other errors
* to that, but there's not much we can do
* about that.)
*/
nlmsg_free(msg);
return 0;
} else {
/*
* Real failure, not just "that device is not
* available.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_send_auto_complete failed adding %s interface: %s",
device, mondevice, nl_geterror(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
}
err = nl_wait_for_ack(state->nl_sock);
if (err < 0) {
if (err == -NLE_FAILURE) {
/*
* Device not available; our caller should just
* keep trying. (libnl 2.x maps ENFILE to
* NLE_FAILURE; it can also map other errors
* to that, but there's not much we can do
* about that.)
*/
nlmsg_free(msg);
return 0;
} else {
/*
* Real failure, not just "that device is not
* available.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_wait_for_ack failed adding %s interface: %s",
device, mondevice, nl_geterror(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
}
/*
* Success.
*/
nlmsg_free(msg);
/*
* Try to remember the monitor device.
*/
handlep->mondevice = strdup(mondevice);
if (handlep->mondevice == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "strdup");
/*
* Get rid of the monitor device.
*/
del_mon_if(handle, sock_fd, state, device, mondevice);
return PCAP_ERROR;
}
return 1;
nla_put_failure:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_put failed adding %s interface",
device, mondevice);
nlmsg_free(msg);
return PCAP_ERROR;
}
static int
del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
const char *device, const char *mondevice)
{
int ifindex;
struct nl_msg *msg;
int err;
ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf);
if (ifindex == -1)
return PCAP_ERROR;
msg = nlmsg_alloc();
if (!msg) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: failed to allocate netlink msg", device);
return PCAP_ERROR;
}
genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
0, NL80211_CMD_DEL_INTERFACE, 0);
NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
err = nl_send_auto_complete(state->nl_sock, msg);
if (err < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_send_auto_complete failed deleting %s interface: %s",
device, mondevice, nl_geterror(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
err = nl_wait_for_ack(state->nl_sock);
if (err < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_wait_for_ack failed adding %s interface: %s",
device, mondevice, nl_geterror(-err));
nlmsg_free(msg);
return PCAP_ERROR;
}
/*
* Success.
*/
nlmsg_free(msg);
return 1;
nla_put_failure:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: nl_put failed deleting %s interface",
device, mondevice);
nlmsg_free(msg);
return PCAP_ERROR;
}
#endif /* HAVE_LIBNL */
static int pcap_protocol(pcap_t *handle)
{
int protocol;
protocol = handle->opt.protocol;
if (protocol == 0)
protocol = ETH_P_ALL;
return htons(protocol);
}
static int
pcap_can_set_rfmon_linux(pcap_t *handle)
{
#ifdef HAVE_LIBNL
char phydev_path[PATH_MAX+1];
int ret;
#endif
if (strcmp(handle->opt.device, "any") == 0) {
/*
* Monitor mode makes no sense on the "any" device.
*/
return 0;
}
#ifdef HAVE_LIBNL
/*
* Bleah. There doesn't seem to be a way to ask a mac80211
* device, through libnl, whether it supports monitor mode;
* we'll just check whether the device appears to be a
* mac80211 device and, if so, assume the device supports
* monitor mode.
*/
ret = get_mac80211_phydev(handle, handle->opt.device, phydev_path,
PATH_MAX);
if (ret < 0)
return ret; /* error */
if (ret == 1)
return 1; /* mac80211 device */
#endif
return 0;
}
/*
* Grabs the number of missed packets by the interface from
* /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors.
*
* Compared to /proc/net/dev this avoids counting software drops,
* but may be unimplemented and just return 0.
* The author has found no straightforward way to check for support.
*/
static long long int
linux_get_stat(const char * if_name, const char * stat) {
ssize_t bytes_read;
int fd;
char buffer[PATH_MAX];
snprintf(buffer, sizeof(buffer), "/sys/class/net/%s/statistics/%s", if_name, stat);
fd = open(buffer, O_RDONLY);
if (fd == -1)
return 0;
bytes_read = read(fd, buffer, sizeof(buffer) - 1);
close(fd);
if (bytes_read == -1)
return 0;
buffer[bytes_read] = '\0';
return strtoll(buffer, NULL, 10);
}
static long long int
linux_if_drops(const char * if_name)
{
long long int missed = linux_get_stat(if_name, "rx_missed_errors");
long long int fifo = linux_get_stat(if_name, "rx_fifo_errors");
return missed + fifo;
}
/*
* Monitor mode is kind of interesting because we have to reset the
* interface before exiting. The problem can't really be solved without
* some daemon taking care of managing usage counts. If we put the
* interface into monitor mode, we set a flag indicating that we must
* take it out of that mode when the interface is closed, and, when
* closing the interface, if that flag is set we take it out of monitor
* mode.
*/
static void pcap_cleanup_linux( pcap_t *handle )
{
struct pcap_linux *handlep = handle->priv;
#ifdef HAVE_LIBNL
struct nl80211_state nlstate;
int ret;
#endif /* HAVE_LIBNL */
if (handlep->must_do_on_close != 0) {
/*
* There's something we have to do when closing this
* pcap_t.
*/
#ifdef HAVE_LIBNL
if (handlep->must_do_on_close & MUST_DELETE_MONIF) {
ret = nl80211_init(handle, &nlstate, handlep->device);
if (ret >= 0) {
ret = del_mon_if(handle, handle->fd, &nlstate,
handlep->device, handlep->mondevice);
nl80211_cleanup(&nlstate);
}
if (ret < 0) {
fprintf(stderr,
"Can't delete monitor interface %s (%s).\n"
"Please delete manually.\n",
handlep->mondevice, handle->errbuf);
}
}
#endif /* HAVE_LIBNL */
/*
* Take this pcap out of the list of pcaps for which we
* have to take the interface out of some mode.
*/
pcapint_remove_from_pcaps_to_close(handle);
}
if (handle->fd != -1) {
/*
* Destroy the ring buffer (assuming we've set it up),
* and unmap it if it's mapped.
*/
destroy_ring(handle);
}
if (handlep->oneshot_buffer != NULL) {
free(handlep->oneshot_buffer);
handlep->oneshot_buffer = NULL;
}
if (handlep->mondevice != NULL) {
free(handlep->mondevice);
handlep->mondevice = NULL;
}
if (handlep->device != NULL) {
free(handlep->device);
handlep->device = NULL;
}
if (handlep->poll_breakloop_fd != -1) {
close(handlep->poll_breakloop_fd);
handlep->poll_breakloop_fd = -1;
}
pcapint_cleanup_live_common(handle);
}
#ifdef HAVE_TPACKET3
/*
* Some versions of TPACKET_V3 have annoying bugs/misfeatures
* around which we have to work. Determine if we have those
* problems or not.
* 3.19 is the first release with a fixed version of
* TPACKET_V3. We treat anything before that as
* not having a fixed version; that may really mean
* it has *no* version.
*/
static int has_broken_tpacket_v3(void)
{
struct utsname utsname;
const char *release;
long major, minor;
int matches, verlen;
/* No version information, assume broken. */
if (uname(&utsname) == -1)
return 1;
release = utsname.release;
/* A malformed version, ditto. */
matches = sscanf(release, "%ld.%ld%n", &major, &minor, &verlen);
if (matches != 2)
return 1;
if (release[verlen] != '.' && release[verlen] != '\0')
return 1;
/* OK, a fixed version. */
if (major > 3 || (major == 3 && minor >= 19))
return 0;
/* Too old :( */
return 1;
}
#endif
/*
* Set the timeout to be used in poll() with memory-mapped packet capture.
*/
static void
set_poll_timeout(struct pcap_linux *handlep)
{
#ifdef HAVE_TPACKET3
int broken_tpacket_v3 = has_broken_tpacket_v3();
#endif
if (handlep->timeout == 0) {
#ifdef HAVE_TPACKET3
/*
* XXX - due to a set of (mis)features in the TPACKET_V3
* kernel code prior to the 3.19 kernel, blocking forever
* with a TPACKET_V3 socket can, if few packets are
* arriving and passing the socket filter, cause most
* packets to be dropped. See libpcap issue #335 for the
* full painful story.
*
* The workaround is to have poll() time out very quickly,
* so we grab the frames handed to us, and return them to
* the kernel, ASAP.
*/
if (handlep->tp_version == TPACKET_V3 && broken_tpacket_v3)
handlep->poll_timeout = 1; /* don't block for very long */
else
#endif
handlep->poll_timeout = -1; /* block forever */
} else if (handlep->timeout > 0) {
#ifdef HAVE_TPACKET3
/*
* For TPACKET_V3, the timeout is handled by the kernel,
* so block forever; that way, we don't get extra timeouts.
* Don't do that if we have a broken TPACKET_V3, though.
*/
if (handlep->tp_version == TPACKET_V3 && !broken_tpacket_v3)
handlep->poll_timeout = -1; /* block forever, let TPACKET_V3 wake us up */
else
#endif
handlep->poll_timeout = handlep->timeout; /* block for that amount of time */
} else {
/*
* Non-blocking mode; we call poll() to pick up error
* indications, but we don't want it to wait for
* anything.
*/
handlep->poll_timeout = 0;
}
}
static void pcap_breakloop_linux(pcap_t *handle)
{
pcapint_breakloop_common(handle);
struct pcap_linux *handlep = handle->priv;
uint64_t value = 1;
if (handlep->poll_breakloop_fd != -1) {
/*
* XXX - pcap_breakloop() doesn't have a return value,
* so we can't indicate an error.
*/
DIAG_OFF_WARN_UNUSED_RESULT
(void)write(handlep->poll_breakloop_fd, &value, sizeof(value));
DIAG_ON_WARN_UNUSED_RESULT
}
}
/*
* Set the offset at which to insert VLAN tags.
* That should be the offset of the type field.
*/
static void
set_vlan_offset(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
switch (handle->linktype) {
case DLT_EN10MB:
/*
* The type field is after the destination and source
* MAC address.
*/
handlep->vlan_offset = 2 * ETH_ALEN;
break;
case DLT_LINUX_SLL:
/*
* The type field is in the last 2 bytes of the
* DLT_LINUX_SLL header.
*/
handlep->vlan_offset = SLL_HDR_LEN - 2;
break;
default:
handlep->vlan_offset = -1; /* unknown */
break;
}
}
/*
* Get a handle for a live capture from the given device. You can
* pass NULL as device to get all packages (without link level
* information of course). If you pass 1 as promisc the interface
* will be set to promiscuous mode (XXX: I think this usage should
* be deprecated and functions be added to select that later allow
* modification of that values -- Torsten).
*/
static int
pcap_activate_linux(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
const char *device;
int is_any_device;
struct ifreq ifr;
int status;
int ret;
device = handle->opt.device;
/*
* Start out assuming no warnings.
*/
status = 0;
/*
* Make sure the name we were handed will fit into the ioctls we
* might perform on the device; if not, return a "No such device"
* indication, as the Linux kernel shouldn't support creating
* a device whose name won't fit into those ioctls.
*
* "Will fit" means "will fit, complete with a null terminator",
* so if the length, which does *not* include the null terminator,
* is greater than *or equal to* the size of the field into which
* we'll be copying it, that won't fit.
*/
if (strlen(device) >= sizeof(ifr.ifr_name)) {
/*
* There's nothing more to say, so clear the error
* message.
*/
handle->errbuf[0] = '\0';
status = PCAP_ERROR_NO_SUCH_DEVICE;
goto fail;
}
/*
* Turn a negative snapshot value (invalid), a snapshot value of
* 0 (unspecified), or a value bigger than the normal maximum
* value, into the maximum allowed value.
*
* If some application really *needs* a bigger snapshot
* length, we should just increase MAXIMUM_SNAPLEN.
*/
if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
handle->snapshot = MAXIMUM_SNAPLEN;
handlep->device = strdup(device);
if (handlep->device == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "strdup");
status = PCAP_ERROR;
goto fail;
}
/*
* The "any" device is a special device which causes us not
* to bind to a particular device and thus to look at all
* devices.
*/
is_any_device = (strcmp(device, "any") == 0);
if (is_any_device) {
if (handle->opt.promisc) {
handle->opt.promisc = 0;
/* Just a warning. */
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Promiscuous mode not supported on the \"any\" device");
status = PCAP_WARNING_PROMISC_NOTSUP;
}
}
/* copy timeout value */
handlep->timeout = handle->opt.timeout;
/*
* If we're in promiscuous mode, then we probably want
* to see when the interface drops packets too, so get an
* initial count from
* /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors
*/
if (handle->opt.promisc)
handlep->sysfs_dropped = linux_if_drops(handlep->device);
/*
* If the "any" device is specified, try to open a SOCK_DGRAM.
* Otherwise, open a SOCK_RAW.
*/
ret = setup_socket(handle, is_any_device);
if (ret < 0) {
/*
* Fatal error; the return value is the error code,
* and handle->errbuf has been set to an appropriate
* error message.
*/
status = ret;
goto fail;
}
if (ret > 0) {
/*
* We got a warning; return that, as handle->errbuf
* might have been overwritten by this warning.
*/
status = ret;
}
/*
* Success (possibly with a warning).
*
* First, try to allocate an event FD for breakloop, if
* we're not going to start in non-blocking mode.
*/
if (!handle->opt.nonblock) {
handlep->poll_breakloop_fd = eventfd(0, EFD_NONBLOCK);
if (handlep->poll_breakloop_fd == -1) {
/*
* Failed.
*/
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "could not open eventfd");
status = PCAP_ERROR;
goto fail;
}
}
/*
* Succeeded.
* Try to set up memory-mapped access.
*/
ret = setup_mmapped(handle);
if (ret < 0) {
/*
* We failed to set up to use it, or the
* kernel supports it, but we failed to
* enable it. The return value is the
* error status to return and, if it's
* PCAP_ERROR, handle->errbuf contains
* the error message.
*/
status = ret;
goto fail;
}
if (ret > 0) {
/*
* We got a warning; return that, as handle->errbuf
* might have been overwritten by this warning.
*/
status = ret;
}
/*
* We succeeded. status has been set to the status to return,
* which might be 0, or might be a PCAP_WARNING_ value.
*/
/*
* Now that we have activated the mmap ring, we can
* set the correct protocol.
*/
if ((ret = iface_bind(handle->fd, handlep->ifindex,
handle->errbuf, pcap_protocol(handle))) != 0) {
status = ret;
goto fail;
}
handle->inject_op = pcap_inject_linux;
handle->setfilter_op = pcap_setfilter_linux;
handle->setdirection_op = pcap_setdirection_linux;
handle->set_datalink_op = pcap_set_datalink_linux;
handle->setnonblock_op = pcap_setnonblock_linux;
handle->getnonblock_op = pcap_getnonblock_linux;
handle->cleanup_op = pcap_cleanup_linux;
handle->stats_op = pcap_stats_linux;
handle->breakloop_op = pcap_breakloop_linux;
switch (handlep->tp_version) {
case TPACKET_V2:
handle->read_op = pcap_read_linux_mmap_v2;
break;
#ifdef HAVE_TPACKET3
case TPACKET_V3:
handle->read_op = pcap_read_linux_mmap_v3;
break;
#endif
}
handle->oneshot_callback = pcapint_oneshot_linux;
handle->selectable_fd = handle->fd;
return status;
fail:
pcap_cleanup_linux(handle);
return status;
}
static int
pcap_set_datalink_linux(pcap_t *handle, int dlt)
{
handle->linktype = dlt;
/*
* Update the offset at which to insert VLAN tags for the
* new link-layer type.
*/
set_vlan_offset(handle);
return 0;
}
/*
* linux_check_direction()
*
* Do checks based on packet direction.
*/
static inline int
linux_check_direction(const pcap_t *handle, const struct sockaddr_ll *sll)
{
struct pcap_linux *handlep = handle->priv;
if (sll->sll_pkttype == PACKET_OUTGOING) {
/*
* Outgoing packet.
* If this is from the loopback device, reject it;
* we'll see the packet as an incoming packet as well,
* and we don't want to see it twice.
*/
if (sll->sll_ifindex == handlep->lo_ifindex)
return 0;
/*
* If this is an outgoing CAN or CAN FD frame, and
* the user doesn't only want outgoing packets,
* reject it; CAN devices and drivers, and the CAN
* stack, always arrange to loop back transmitted
* packets, so they also appear as incoming packets.
* We don't want duplicate packets, and we can't
* easily distinguish packets looped back by the CAN
* layer than those received by the CAN layer, so we
* eliminate this packet instead.
*
* We check whether this is a CAN or CAN FD frame
* by checking whether the device's hardware type
* is ARPHRD_CAN.
*/
if (sll->sll_hatype == ARPHRD_CAN &&
handle->direction != PCAP_D_OUT)
return 0;
/*
* If the user only wants incoming packets, reject it.
*/
if (handle->direction == PCAP_D_IN)
return 0;
} else {
/*
* Incoming packet.
* If the user only wants outgoing packets, reject it.
*/
if (handle->direction == PCAP_D_OUT)
return 0;
}
return 1;
}
/*
* Check whether the device to which the pcap_t is bound still exists.
* We do so by asking what address the socket is bound to, and checking
* whether the ifindex in the address is -1, meaning "that device is gone",
* or some other value, meaning "that device still exists".
*/
static int
device_still_exists(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
struct sockaddr_ll addr;
socklen_t addr_len;
/*
* If handlep->ifindex is -1, the socket isn't bound, meaning
* we're capturing on the "any" device; that device never
* disappears. (It should also never be configured down, so
* we shouldn't even get here, but let's make sure.)
*/
if (handlep->ifindex == -1)
return (1); /* it's still here */
/*
* OK, now try to get the address for the socket.
*/
addr_len = sizeof (addr);
if (getsockname(handle->fd, (struct sockaddr *) &addr, &addr_len) == -1) {
/*
* Error - report an error and return -1.
*/
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "getsockname failed");
return (-1);
}
if (addr.sll_ifindex == -1) {
/*
* This means the device went away.
*/
return (0);
}
/*
* The device presumably just went down.
*/
return (1);
}
static int
pcap_inject_linux(pcap_t *handle, const void *buf, int size)
{
struct pcap_linux *handlep = handle->priv;
int ret;
if (handlep->ifindex == -1) {
/*
* We don't support sending on the "any" device.
*/
pcapint_strlcpy(handle->errbuf,
"Sending packets isn't supported on the \"any\" device",
PCAP_ERRBUF_SIZE);
return (-1);
}
if (handlep->cooked) {
/*
* We don't support sending on cooked-mode sockets.
*
* XXX - how do you send on a bound cooked-mode
* socket?
* Is a "sendto()" required there?
*/
pcapint_strlcpy(handle->errbuf,
"Sending packets isn't supported in cooked mode",
PCAP_ERRBUF_SIZE);
return (-1);
}
ret = (int)send(handle->fd, buf, size, 0);
if (ret == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "send");
return (-1);
}
return (ret);
}
/*
* Get the statistics for the given packet capture handle.
*/
static int
pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
{
struct pcap_linux *handlep = handle->priv;
#ifdef HAVE_TPACKET3
/*
* For sockets using TPACKET_V2, the extra stuff at the end
* of a struct tpacket_stats_v3 will not be filled in, and
* we don't look at it so this is OK even for those sockets.
* In addition, the PF_PACKET socket code in the kernel only
* uses the length parameter to compute how much data to
* copy out and to indicate how much data was copied out, so
* it's OK to base it on the size of a struct tpacket_stats.
*
* XXX - it's probably OK, in fact, to just use a
* struct tpacket_stats for V3 sockets, as we don't
* care about the tp_freeze_q_cnt stat.
*/
struct tpacket_stats_v3 kstats;
#else /* HAVE_TPACKET3 */
struct tpacket_stats kstats;
#endif /* HAVE_TPACKET3 */
socklen_t len = sizeof (struct tpacket_stats);
long long if_dropped = 0;
/*
* To fill in ps_ifdrop, we parse
* /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors
* for the numbers
*/
if (handle->opt.promisc)
{
/*
* XXX - is there any reason to do this by remembering
* the last counts value, subtracting it from the
* current counts value, and adding that to stat.ps_ifdrop,
* maintaining stat.ps_ifdrop as a count, rather than just
* saving the *initial* counts value and setting
* stat.ps_ifdrop to the difference between the current
* value and the initial value?
*
* One reason might be to handle the count wrapping
* around, on platforms where the count is 32 bits
* and where you might get more than 2^32 dropped
* packets; is there any other reason?
*
* (We maintain the count as a long long int so that,
* if the kernel maintains the counts as 64-bit even
* on 32-bit platforms, we can handle the real count.
*
* Unfortunately, we can't report 64-bit counts; we
* need a better API for reporting statistics, such as
* one that reports them in a style similar to the
* pcapng Interface Statistics Block, so that 1) the
* counts are 64-bit, 2) it's easier to add new statistics
* without breaking the ABI, and 3) it's easier to
* indicate to a caller that wants one particular
* statistic that it's not available by just not supplying
* it.)
*/
if_dropped = handlep->sysfs_dropped;
handlep->sysfs_dropped = linux_if_drops(handlep->device);
handlep->stat.ps_ifdrop += (u_int)(handlep->sysfs_dropped - if_dropped);
}
/*
* Try to get the packet counts from the kernel.
*/
if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
&kstats, &len) > -1) {
/*
* "ps_recv" counts only packets that *passed* the
* filter, not packets that didn't pass the filter.
* This includes packets later dropped because we
* ran out of buffer space.
*
* "ps_drop" counts packets dropped because we ran
* out of buffer space. It doesn't count packets
* dropped by the interface driver. It counts only
* packets that passed the filter.
*
* See above for ps_ifdrop.
*
* Both statistics include packets not yet read from
* the kernel by libpcap, and thus not yet seen by
* the application.
*
* In "linux/net/packet/af_packet.c", at least in 2.6.27
* through 5.6 kernels, "tp_packets" is incremented for
* every packet that passes the packet filter *and* is
* successfully copied to the ring buffer; "tp_drops" is
* incremented for every packet dropped because there's
* not enough free space in the ring buffer.
*
* When the statistics are returned for a PACKET_STATISTICS
* "getsockopt()" call, "tp_drops" is added to "tp_packets",
* so that "tp_packets" counts all packets handed to
* the PF_PACKET socket, including packets dropped because
* there wasn't room on the socket buffer - but not
* including packets that didn't pass the filter.
*
* In the BSD BPF, the count of received packets is
* incremented for every packet handed to BPF, regardless
* of whether it passed the filter.
*
* We can't make "pcap_stats()" work the same on both
* platforms, but the best approximation is to return
* "tp_packets" as the count of packets and "tp_drops"
* as the count of drops.
*
* Keep a running total because each call to
* getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
* resets the counters to zero.
*/
handlep->stat.ps_recv += kstats.tp_packets;
handlep->stat.ps_drop += kstats.tp_drops;
*stats = handlep->stat;
return 0;
}
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno,
"failed to get statistics from socket");
return -1;
}
/*
* A PF_PACKET socket can be bound to any network interface.
*/
static int
can_be_bound(const char *name _U_)
{
return (1);
}
/*
* Get a socket to use with various interface ioctls.
*/
static int
get_if_ioctl_socket(void)
{
int fd;
/*
* This is a bit ugly.
*
* There isn't a socket type that's guaranteed to work.
*
* AF_NETLINK will work *if* you have Netlink configured into the
* kernel (can it be configured out if you have any networking
* support at all?) *and* if you're running a sufficiently recent
* kernel, but not all the kernels we support are sufficiently
* recent - that feature was introduced in Linux 4.6.
*
* AF_UNIX will work *if* you have UNIX-domain sockets configured
* into the kernel and *if* you're not on a system that doesn't
* allow them - some SELinux systems don't allow you create them.
* Most systems probably have them configured in, but not all systems
* have them configured in and allow them to be created.
*
* AF_INET will work *if* you have IPv4 configured into the kernel,
* but, apparently, some systems have network adapters but have
* kernels without IPv4 support.
*
* AF_INET6 will work *if* you have IPv6 configured into the
* kernel, but if you don't have AF_INET, you might not have
* AF_INET6, either (that is, independently on its own grounds).
*
* AF_PACKET would work, except that some of these calls should
* work even if you *don't* have capture permission (you should be
* able to enumerate interfaces and get information about them
* without capture permission; you shouldn't get a failure until
* you try pcap_activate()). (If you don't allow programs to
* get as much information as possible about interfaces if you
* don't have permission to capture, you run the risk of users
* asking "why isn't it showing XXX" - or, worse, if you don't
* show interfaces *at all* if you don't have permission to
* capture on them, "why do no interfaces show up?" - when the
* real problem is a permissions problem. Error reports of that
* type require a lot more back-and-forth to debug, as evidenced
* by many Wireshark bugs/mailing list questions/Q&A questions.)
*
* So:
*
* we first try an AF_NETLINK socket, where "try" includes
* "try to do a device ioctl on it", as, in the future, once
* pre-4.6 kernels are sufficiently rare, that will probably
* be the mechanism most likely to work;
*
* if that fails, we try an AF_UNIX socket, as that's less
* likely to be configured out on a networking-capable system
* than is IP;
*
* if that fails, we try an AF_INET6 socket;
*
* if that fails, we try an AF_INET socket.
*/
fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
if (fd != -1) {
/*
* OK, let's make sure we can do an SIOCGIFNAME
* ioctl.
*/
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
if (ioctl(fd, SIOCGIFNAME, &ifr) == 0 ||
errno != EOPNOTSUPP) {
/*
* It succeeded, or failed for some reason
* other than "netlink sockets don't support
* device ioctls". Go with the AF_NETLINK
* socket.
*/
return (fd);
}
/*
* OK, that didn't work, so it's as bad as "netlink
* sockets aren't available". Close the socket and
* drive on.
*/
close(fd);
}
/*
* Now try an AF_UNIX socket.
*/
fd = socket(AF_UNIX, SOCK_RAW, 0);
if (fd != -1) {
/*
* OK, we got it!
*/
return (fd);
}
/*
* Now try an AF_INET6 socket.
*/
fd = socket(AF_INET6, SOCK_DGRAM, 0);
if (fd != -1) {
return (fd);
}
/*
* Now try an AF_INET socket.
*
* XXX - if that fails, is there anything else we should try?
* AF_CAN, for embedded systems in vehicles, in case they're
* built without Internet protocol support? Any other socket
* types popular in non-Internet embedded systems?
*/
return (socket(AF_INET, SOCK_DGRAM, 0));
}
/*
* Get additional flags for a device, using SIOCGIFMEDIA.
*/
static int
get_if_flags(const char *name, bpf_u_int32 *flags, char *errbuf)
{
int sock;
FILE *fh;
unsigned int arptype;
struct ifreq ifr;
struct ethtool_value info;
if (*flags & PCAP_IF_LOOPBACK) {
/*
* Loopback devices aren't wireless, and "connected"/
* "disconnected" doesn't apply to them.
*/
*flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE;
return 0;
}
sock = get_if_ioctl_socket();
if (sock == -1) {
pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, errno,
"Can't create socket to get ethtool information for %s",
name);
return -1;
}
/*
* OK, what type of network is this?
* In particular, is it wired or wireless?
*/
if (is_wifi(name)) {
/*
* Wi-Fi, hence wireless.
*/
*flags |= PCAP_IF_WIRELESS;
} else {
/*
* OK, what does /sys/class/net/{if_name}/type contain?
* (We don't use that for Wi-Fi, as it'll report
* "Ethernet", i.e. ARPHRD_ETHER, for non-monitor-
* mode devices.)
*/
char *pathstr;
if (asprintf(&pathstr, "/sys/class/net/%s/type", name) == -1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"%s: Can't generate path name string for /sys/class/net device",
name);
close(sock);
return -1;
}
fh = fopen(pathstr, "r");
if (fh != NULL) {
if (fscanf(fh, "%u", &arptype) == 1) {
/*
* OK, we got an ARPHRD_ type; what is it?
*/
switch (arptype) {
case ARPHRD_LOOPBACK:
/*
* These are types to which
* "connected" and "disconnected"
* don't apply, so don't bother
* asking about it.
*
* XXX - add other types?
*/
close(sock);
fclose(fh);
free(pathstr);
return 0;
case ARPHRD_IRDA:
case ARPHRD_IEEE80211:
case ARPHRD_IEEE80211_PRISM:
case ARPHRD_IEEE80211_RADIOTAP:
#ifdef ARPHRD_IEEE802154
case ARPHRD_IEEE802154:
#endif
#ifdef ARPHRD_IEEE802154_MONITOR
case ARPHRD_IEEE802154_MONITOR:
#endif
#ifdef ARPHRD_6LOWPAN
case ARPHRD_6LOWPAN:
#endif
/*
* Various wireless types.
*/
*flags |= PCAP_IF_WIRELESS;
break;
}
}
fclose(fh);
}
free(pathstr);
}
#ifdef ETHTOOL_GLINK
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
info.cmd = ETHTOOL_GLINK;
/*
* XXX - while Valgrind handles SIOCETHTOOL and knows that
* the ETHTOOL_GLINK command sets the .data member of the
* structure, Memory Sanitizer doesn't yet do so:
*
*
https://bugs.llvm.org/show_bug.cgi?id=45814
*
* For now, we zero it out to squelch warnings; if the bug
* in question is fixed, we can remove this.
*/
info.data = 0;
ifr.ifr_data = (caddr_t)&info;
if (ioctl(sock, SIOCETHTOOL, &ifr) == -1) {
int save_errno = errno;
switch (save_errno) {
case EOPNOTSUPP:
case EINVAL:
/*
* OK, this OS version or driver doesn't support
* asking for this information.
* XXX - distinguish between "this doesn't
* support ethtool at all because it's not
* that type of device" vs. "this doesn't
* support ethtool even though it's that
* type of device", and return "unknown".
*/
*flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE;
close(sock);
return 0;
case ENODEV:
/*
* OK, no such device.
* The user will find that out when they try to
* activate the device; just say "OK" and
* don't set anything.
*/
close(sock);
return 0;
default:
/*
* Other error.
*/
pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
save_errno,
"%s: SIOCETHTOOL(ETHTOOL_GLINK) ioctl failed",
name);
close(sock);
return -1;
}
}
/*
* Is it connected?
*/
if (info.data) {
/*
* It's connected.
*/
*flags |= PCAP_IF_CONNECTION_STATUS_CONNECTED;
} else {
/*
* It's disconnected.
*/
*flags |= PCAP_IF_CONNECTION_STATUS_DISCONNECTED;
}
#endif
close(sock);
return 0;
}
int
pcapint_platform_finddevs(pcap_if_list_t *devlistp, char *errbuf)
{
/*
* Get the list of regular interfaces first.
*/
if (pcapint_findalldevs_interfaces(devlistp, errbuf, can_be_bound,
get_if_flags) == -1)
return (-1); /* failure */
/*
* Add the "any" device.
*/
if (pcap_add_any_dev(devlistp, errbuf) == NULL)
return (-1);
return (0);
}
/*
* Set direction flag: Which packets do we accept on a forwarding
* single device? IN, OUT or both?
*/
static int
pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
{
/*
* It's guaranteed, at this point, that d is a valid
* direction value.
*/
handle->direction = d;
return 0;
}
static int
is_wifi(const char *device)
{
char *pathstr;
struct stat statb;
/*
* See if there's a sysfs wireless directory for it.
* If so, it's a wireless interface.
*/
if (asprintf(&pathstr, "/sys/class/net/%s/wireless", device) == -1) {
/*
* Just give up here.
*/
return 0;
}
if (stat(pathstr, &statb) == 0) {
free(pathstr);
return 1;
}
free(pathstr);
return 0;
}
/*
* Linux uses the ARP hardware type to identify the type of an
* interface. pcap uses the DLT_xxx constants for this. This
* function takes a pointer to a "pcap_t", and an ARPHRD_xxx
* constant, as arguments, and sets "handle->linktype" to the
* appropriate DLT_XXX constant and sets "handle->offset" to
* the appropriate value (to make "handle->offset" plus link-layer
* header length be a multiple of 4, so that the link-layer payload
* will be aligned on a 4-byte boundary when capturing packets).
* (If the offset isn't set here, it'll be 0; add code as appropriate
* for cases where it shouldn't be 0.)
*
* If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
* in cooked mode; otherwise, we can't use cooked mode, so we have
* to pick some type that works in raw mode, or fail.
*
* Sets the link type to -1 if unable to map the type.
*
* Returns 0 on success or a PCAP_ERROR_ value on error.
*/
static int map_arphrd_to_dlt(pcap_t *handle, int arptype,
const char *device, int cooked_ok)
{
static const char cdma_rmnet[] = "cdma_rmnet";
switch (arptype) {
case ARPHRD_ETHER:
/*
* For various annoying reasons having to do with DHCP
* software, some versions of Android give the mobile-
* phone-network interface an ARPHRD_ value of
* ARPHRD_ETHER, even though the packets supplied by
* that interface have no link-layer header, and begin
* with an IP header, so that the ARPHRD_ value should
* be ARPHRD_NONE.
*
* Detect those devices by checking the device name, and
* use DLT_RAW for them.
*/
if (strncmp(device, cdma_rmnet, sizeof cdma_rmnet - 1) == 0) {
handle->linktype = DLT_RAW;
return 0;
}
/*
* Is this a real Ethernet device? If so, give it a
* link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
* that an application can let you choose it, in case you're
* capturing DOCSIS traffic that a Cisco Cable Modem
* Termination System is putting out onto an Ethernet (it
* doesn't put an Ethernet header onto the wire, it puts raw
* DOCSIS frames out on the wire inside the low-level
* Ethernet framing).
*
* XXX - are there any other sorts of "fake Ethernet" that
* have ARPHRD_ETHER but that shouldn't offer DLT_DOCSIS as
* a Cisco CMTS won't put traffic onto it or get traffic
* bridged onto it? ISDN is handled in "setup_socket()",
* as we fall back on cooked mode there, and we use
* is_wifi() to check for 802.11 devices; are there any
* others?
*/
if (!is_wifi(device)) {
int ret;
/*
* This is not a Wi-Fi device but it could be
* a DSA master/management network device.
*/
ret = iface_dsa_get_proto_info(device, handle);
if (ret < 0)
return ret;
if (ret == 1) {
/*
* This is a DSA master/management network
* device linktype is already set by
* iface_dsa_get_proto_info() set an
* appropriate offset here.
*/
handle->offset = 2;
break;
}
/*
* It's not a Wi-Fi device; offer DOCSIS.
*/
handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
if (handle->dlt_list == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "malloc");
return (PCAP_ERROR);
}
handle->dlt_list[0] = DLT_EN10MB;
handle->dlt_list[1] = DLT_DOCSIS;
handle->dlt_count = 2;
}
/* FALLTHROUGH */
case ARPHRD_METRICOM:
case ARPHRD_LOOPBACK:
handle->linktype = DLT_EN10MB;
handle->offset = 2;
break;
case ARPHRD_EETHER:
handle->linktype = DLT_EN3MB;
break;
case ARPHRD_AX25:
handle->linktype = DLT_AX25_KISS;
break;
case ARPHRD_PRONET:
handle->linktype = DLT_PRONET;
break;
case ARPHRD_CHAOS:
handle->linktype = DLT_CHAOS;
break;
#ifndef ARPHRD_CAN
#define ARPHRD_CAN 280
#endif
case ARPHRD_CAN:
handle->linktype = DLT_CAN_SOCKETCAN;
break;
#ifndef ARPHRD_IEEE802_TR
#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
#endif
case ARPHRD_IEEE802_TR:
case ARPHRD_IEEE802:
handle->linktype = DLT_IEEE802;
handle->offset = 2;
break;
case ARPHRD_ARCNET:
handle->linktype = DLT_ARCNET_LINUX;
break;
#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
#define ARPHRD_FDDI 774
#endif
case ARPHRD_FDDI:
handle->linktype = DLT_FDDI;
handle->offset = 3;
break;
#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
#define ARPHRD_ATM 19
#endif
case ARPHRD_ATM:
/*
* The Classical IP implementation in ATM for Linux
* supports both what RFC 1483 calls "LLC Encapsulation",
* in which each packet has an LLC header, possibly
* with a SNAP header as well, prepended to it, and
* what RFC 1483 calls "VC Based Multiplexing", in which
* different virtual circuits carry different network
* layer protocols, and no header is prepended to packets.
*
* They both have an ARPHRD_ type of ARPHRD_ATM, so
* you can't use the ARPHRD_ type to find out whether
* captured packets will have an LLC header, and,
* while there's a socket ioctl to *set* the encapsulation
* type, there's no ioctl to *get* the encapsulation type.
*
* This means that
*
* programs that dissect Linux Classical IP frames
* would have to check for an LLC header and,
* depending on whether they see one or not, dissect
* the frame as LLC-encapsulated or as raw IP (I
* don't know whether there's any traffic other than
* IP that would show up on the socket, or whether
* there's any support for IPv6 in the Linux
* Classical IP code);
*
* filter expressions would have to compile into
* code that checks for an LLC header and does
* the right thing.
*
* Both of those are a nuisance - and, at least on systems
* that support PF_PACKET sockets, we don't have to put
* up with those nuisances; instead, we can just capture
* in cooked mode. That's what we'll do, if we can.
* Otherwise, we'll just fail.
*/
if (cooked_ok)
handle->linktype = DLT_LINUX_SLL;
else
handle->linktype = -1;
break;
#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
#define ARPHRD_IEEE80211 801
#endif
case ARPHRD_IEEE80211:
handle->linktype = DLT_IEEE802_11;
break;
#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
#define ARPHRD_IEEE80211_PRISM 802
#endif
case ARPHRD_IEEE80211_PRISM:
handle->linktype = DLT_PRISM_HEADER;
break;
#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
#define ARPHRD_IEEE80211_RADIOTAP 803
#endif
case ARPHRD_IEEE80211_RADIOTAP:
handle->linktype = DLT_IEEE802_11_RADIO;
break;
case ARPHRD_PPP:
/*
* Some PPP code in the kernel supplies no link-layer
* header whatsoever to PF_PACKET sockets; other PPP
* code supplies PPP link-layer headers ("syncppp.c");
* some PPP code might supply random link-layer
* headers (PPP over ISDN - there's code in Ethereal,
* for example, to cope with PPP-over-ISDN captures
* with which the Ethereal developers have had to cope,
* heuristically trying to determine which of the
* oddball link-layer headers particular packets have).
*
* As such, we just punt, and run all PPP interfaces
* in cooked mode, if we can; otherwise, we just treat
* it as DLT_RAW, for now - if somebody needs to capture,
* on a 2.0[.x] kernel, on PPP devices that supply a
* link-layer header, they'll have to add code here to
* map to the appropriate DLT_ type (possibly adding a
* new DLT_ type, if necessary).
*/
if (cooked_ok)
handle->linktype = DLT_LINUX_SLL;
else {
/*
* XXX - handle ISDN types here? We can't fall
* back on cooked sockets, so we'd have to
* figure out from the device name what type of
* link-layer encapsulation it's using, and map
* that to an appropriate DLT_ value, meaning
* we'd map "isdnN" devices to DLT_RAW (they
* supply raw IP packets with no link-layer
* header) and "isdY" devices to a new DLT_I4L_IP
* type that has only an Ethernet packet type as
* a link-layer header.
*
* But sometimes we seem to get random crap
* in the link-layer header when capturing on
* ISDN devices....
*/
handle->linktype = DLT_RAW;
}
break;
#ifndef ARPHRD_CISCO
#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
#endif
case ARPHRD_CISCO:
handle->linktype = DLT_C_HDLC;
break;
/* Not sure if this is correct for all tunnels, but it
* works for CIPE */
case ARPHRD_TUNNEL:
#ifndef ARPHRD_SIT
#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
#endif
case ARPHRD_SIT:
case ARPHRD_CSLIP:
case ARPHRD_SLIP6:
case ARPHRD_CSLIP6:
case ARPHRD_ADAPT:
case ARPHRD_SLIP:
#ifndef ARPHRD_RAWHDLC
#define ARPHRD_RAWHDLC 518
#endif
case ARPHRD_RAWHDLC:
#ifndef ARPHRD_DLCI
#define ARPHRD_DLCI 15
#endif
case ARPHRD_DLCI:
/*
* XXX - should some of those be mapped to DLT_LINUX_SLL
* instead? Should we just map all of them to DLT_LINUX_SLL?
*/
handle->linktype = DLT_RAW;
break;
#ifndef ARPHRD_FRAD
#define ARPHRD_FRAD 770
#endif
case ARPHRD_FRAD:
handle->linktype = DLT_FRELAY;
break;
case ARPHRD_LOCALTLK:
handle->linktype = DLT_LTALK;
break;
case 18:
/*
* RFC 4338 defines an encapsulation for IP and ARP
* packets that's compatible with the RFC 2625
* encapsulation, but that uses a different ARP
* hardware type and hardware addresses. That
* ARP hardware type is 18; Linux doesn't define
* any ARPHRD_ value as 18, but if it ever officially
* supports RFC 4338-style IP-over-FC, it should define
* one.
*
* For now, we map it to DLT_IP_OVER_FC, in the hopes
* that this will encourage its use in the future,
* should Linux ever officially support RFC 4338-style
* IP-over-FC.
*/
handle->linktype = DLT_IP_OVER_FC;
break;
#ifndef ARPHRD_FCPP
#define ARPHRD_FCPP 784
#endif
case ARPHRD_FCPP:
#ifndef ARPHRD_FCAL
#define ARPHRD_FCAL 785
#endif
case ARPHRD_FCAL:
#ifndef ARPHRD_FCPL
#define ARPHRD_FCPL 786
#endif
case ARPHRD_FCPL:
#ifndef ARPHRD_FCFABRIC
#define ARPHRD_FCFABRIC 787
#endif
case ARPHRD_FCFABRIC:
/*
* Back in 2002, Donald Lee at Cray wanted a DLT_ for
* IP-over-FC:
*
*
https://www.mail-archive.com/tcpdump-workers@sandelman.ottawa.on.ca/msg01043.html
*
* and one was assigned.
*
* In a later private discussion (spun off from a message
* on the ethereal-users list) on how to get that DLT_
* value in libpcap on Linux, I ended up deciding that
* the best thing to do would be to have him tweak the
* driver to set the ARPHRD_ value to some ARPHRD_FCxx
* type, and map all those types to DLT_IP_OVER_FC:
*
* I've checked into the libpcap and tcpdump CVS tree
* support for DLT_IP_OVER_FC. In order to use that,
* you'd have to modify your modified driver to return
* one of the ARPHRD_FCxxx types, in "fcLINUXfcp.c" -
* change it to set "dev->type" to ARPHRD_FCFABRIC, for
* example (the exact value doesn't matter, it can be
* any of ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL, or
* ARPHRD_FCFABRIC).
*
* 11 years later, Christian Svensson wanted to map
* various ARPHRD_ values to DLT_FC_2 and
* DLT_FC_2_WITH_FRAME_DELIMS for raw Fibre Channel
* frames:
*
*
https://github.com/mcr/libpcap/pull/29
*
* There doesn't seem to be any network drivers that uses
* any of the ARPHRD_FC* values for IP-over-FC, and
* it's not exactly clear what the "Dummy types for non
* ARP hardware" are supposed to mean (link-layer
* header type? Physical network type?), so it's
* not exactly clear why the ARPHRD_FC* types exist
* in the first place.
*
* For now, we map them to DLT_FC_2, and provide an
* option of DLT_FC_2_WITH_FRAME_DELIMS, as well as
* DLT_IP_OVER_FC just in case there's some old
* driver out there that uses one of those types for
* IP-over-FC on which somebody wants to capture
* packets.
*/
handle->linktype = DLT_FC_2;
handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 3);
if (handle->dlt_list == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "malloc");
return (PCAP_ERROR);
}
handle->dlt_list[0] = DLT_FC_2;
handle->dlt_list[1] = DLT_FC_2_WITH_FRAME_DELIMS;
handle->dlt_list[2] = DLT_IP_OVER_FC;
handle->dlt_count = 3;
break;
#ifndef ARPHRD_IRDA
#define ARPHRD_IRDA 783
#endif
case ARPHRD_IRDA:
/* Don't expect IP packet out of this interfaces... */
handle->linktype = DLT_LINUX_IRDA;
/* We need to save packet direction for IrDA decoding,
* so let's use "Linux-cooked" mode. Jean II
*
* XXX - this is handled in setup_socket(). */
/* handlep->cooked = 1; */
break;
/* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation
* is needed, please report it to <
[email protected]> */
#ifndef ARPHRD_LAPD
#define ARPHRD_LAPD 8445
#endif
case ARPHRD_LAPD:
/* Don't expect IP packet out of this interfaces... */
handle->linktype = DLT_LINUX_LAPD;
break;
#ifndef ARPHRD_NONE
#define ARPHRD_NONE 0xFFFE
#endif
case ARPHRD_NONE:
/*
* No link-layer header; packets are just IP
* packets, so use DLT_RAW.
*/
handle->linktype = DLT_RAW;
break;
#ifndef ARPHRD_IEEE802154
#define ARPHRD_IEEE802154 804
#endif
case ARPHRD_IEEE802154:
handle->linktype = DLT_IEEE802_15_4_NOFCS;
break;
#ifndef ARPHRD_NETLINK
#define ARPHRD_NETLINK 824
#endif
case ARPHRD_NETLINK:
handle->linktype = DLT_NETLINK;
/*
* We need to use cooked mode, so that in sll_protocol we
* pick up the netlink protocol type such as NETLINK_ROUTE,
* NETLINK_GENERIC, NETLINK_FIB_LOOKUP, etc.
*
* XXX - this is handled in setup_socket().
*/
/* handlep->cooked = 1; */
break;
#ifndef ARPHRD_VSOCKMON
#define ARPHRD_VSOCKMON 826
#endif
case ARPHRD_VSOCKMON:
handle->linktype = DLT_VSOCK;
break;
default:
handle->linktype = -1;
break;
}
return (0);
}
/*
* Try to set up a PF_PACKET socket.
* Returns 0 or a PCAP_WARNING_ value on success and a PCAP_ERROR_ value
* on failure.
*/
static int
setup_socket(pcap_t *handle, int is_any_device)
{
struct pcap_linux *handlep = handle->priv;
const char *device = handle->opt.device;
int status = 0;
int sock_fd, arptype;
int val;
int err = 0;
struct packet_mreq mr;
#if defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT)
int bpf_extensions;
socklen_t len = sizeof(bpf_extensions);
#endif
/*
* Open a socket with protocol family packet. If cooked is true,
* we open a SOCK_DGRAM socket for the cooked interface, otherwise
* we open a SOCK_RAW socket for the raw interface.
*
* The protocol is set to 0. This means we will receive no
* packets until we "bind" the socket with a non-zero
* protocol. This allows us to setup the ring buffers without
* dropping any packets.
*/
sock_fd = is_any_device ?
socket(PF_PACKET, SOCK_DGRAM, 0) :
socket(PF_PACKET, SOCK_RAW, 0);
if (sock_fd == -1) {
if (errno == EPERM || errno == EACCES) {
/*
* You don't have permission to open the
* socket.
*/
status = PCAP_ERROR_PERM_DENIED;
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Attempt to create packet socket failed - CAP_NET_RAW may be required");
} else if (errno == EAFNOSUPPORT) {
/*
* PF_PACKET sockets not supported.
* Perhaps we're running on the WSL1 module
* in the Windows NT kernel rather than on
* a real Linux kernel.
*/
status = PCAP_ERROR_CAPTURE_NOTSUP;
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"PF_PACKET sockets not supported - is this WSL1?");
} else {
/*
* Other error.
*/
status = PCAP_ERROR;
}
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "socket");
return status;
}
/*
* Get the interface index of the loopback device.
* If the attempt fails, don't fail, just set the
* "handlep->lo_ifindex" to -1.
*
* XXX - can there be more than one device that loops
* packets back, i.e. devices other than "lo"? If so,
* we'd need to find them all, and have an array of
* indices for them, and check all of them in
* "pcap_read_packet()".
*/
handlep->lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf);
/*
* Default value for offset to align link-layer payload
* on a 4-byte boundary.
*/
handle->offset = 0;
/*
* What kind of frames do we have to deal with? Fall back
* to cooked mode if we have an unknown interface type
* or a type we know doesn't work well in raw mode.
*/
if (!is_any_device) {
/* Assume for now we don't need cooked mode. */
handlep->cooked = 0;
if (handle->opt.rfmon) {
/*
* We were asked to turn on monitor mode.
* Do so before we get the link-layer type,
* because entering monitor mode could change
* the link-layer type.
*/
err = enter_rfmon_mode(handle, sock_fd, device);
if (err < 0) {
/* Hard failure */
close(sock_fd);
return err;
}
if (err == 0) {
/*
* Nothing worked for turning monitor mode
* on.
*/
close(sock_fd);
return PCAP_ERROR_RFMON_NOTSUP;
}
/*
* Either monitor mode has been turned on for
* the device, or we've been given a different
* device to open for monitor mode. If we've
* been given a different device, use it.
*/
if (handlep->mondevice != NULL)
device = handlep->mondevice;
}
arptype = iface_get_arptype(sock_fd, device, handle->errbuf);
if (arptype < 0) {
close(sock_fd);
return arptype;
}
status = map_arphrd_to_dlt(handle, arptype, device, 1);
if (status < 0) {
close(sock_fd);
return status;
}
if (handle->linktype == -1 ||
handle->linktype == DLT_LINUX_SLL ||
handle->linktype == DLT_LINUX_IRDA ||
handle->linktype == DLT_LINUX_LAPD ||
handle->linktype == DLT_NETLINK ||
(handle->linktype == DLT_EN10MB &&
(strncmp("isdn", device, 4) == 0 ||
strncmp("isdY", device, 4) == 0))) {
/*
* Unknown interface type (-1), or a
* device we explicitly chose to run
* in cooked mode (e.g., PPP devices),
* or an ISDN device (whose link-layer
* type we can only determine by using
* APIs that may be different on different
* kernels) - reopen in cooked mode.
*
* If the type is unknown, return a warning;
* map_arphrd_to_dlt() has already set the
* warning message.
*/
if (close(sock_fd) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "close");
return PCAP_ERROR;
}
sock_fd = socket(PF_PACKET, SOCK_DGRAM, 0);
if (sock_fd < 0) {
/*
* Fatal error. We treat this as
* a generic error; we already know
* that we were able to open a
* PF_PACKET/SOCK_RAW socket, so
* any failure is a "this shouldn't
* happen" case.
*/
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "socket");
return PCAP_ERROR;
}
handlep->cooked = 1;
/*
* Get rid of any link-layer type list
* we allocated - this only supports cooked
* capture.
*/
if (handle->dlt_list != NULL) {
free(handle->dlt_list);
handle->dlt_list = NULL;
handle->dlt_count = 0;
}
if (handle->linktype == -1) {
/*
* Warn that we're falling back on
* cooked mode; we may want to
* update "map_arphrd_to_dlt()"
* to handle the new type.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"arptype %d not "
"supported by libpcap - "
"falling back to cooked "
"socket",
arptype);
status = PCAP_WARNING;
}
/*
* IrDA capture is not a real "cooked" capture,
* it's IrLAP frames, not IP packets. The
* same applies to LAPD capture.
*/
if (handle->linktype != DLT_LINUX_IRDA &&
handle->linktype != DLT_LINUX_LAPD &&
handle->linktype != DLT_NETLINK)
handle->linktype = DLT_LINUX_SLL;
}
handlep->ifindex = iface_get_id(sock_fd, device,
handle->errbuf);
if (handlep->ifindex == -1) {
close(sock_fd);
return PCAP_ERROR;
}
if ((err = iface_bind(sock_fd, handlep->ifindex,
handle->errbuf, 0)) != 0) {
close(sock_fd);
return err;
}
} else {
/*
* The "any" device.
*/
if (handle->opt.rfmon) {
/*
* It doesn't support monitor mode.
*/
close(sock_fd);
return PCAP_ERROR_RFMON_NOTSUP;
}
/*
* It uses cooked mode.
* Support both DLT_LINUX_SLL and DLT_LINUX_SLL2.
*/
handlep->cooked = 1;
handle->linktype = DLT_LINUX_SLL;
handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
if (handle->dlt_list == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "malloc");
return (PCAP_ERROR);
}
handle->dlt_list[0] = DLT_LINUX_SLL;
handle->dlt_list[1] = DLT_LINUX_SLL2;
handle->dlt_count = 2;
/*
* We're not bound to a device.
* For now, we're using this as an indication
* that we can't transmit; stop doing that only
* if we figure out how to transmit in cooked
* mode.
*/
handlep->ifindex = -1;
}
/*
* Select promiscuous mode on if "promisc" is set.
*
* Do not turn allmulti mode on if we don't select
* promiscuous mode - on some devices (e.g., Orinoco
* wireless interfaces), allmulti mode isn't supported
* and the driver implements it by turning promiscuous
* mode on, and that screws up the operation of the
* card as a normal networking interface, and on no
* other platform I know of does starting a non-
* promiscuous capture affect which multicast packets
* are received by the interface.
*/
/*
* Hmm, how can we set promiscuous mode on all interfaces?
* I am not sure if that is possible at all. For now, we
* silently ignore attempts to turn promiscuous mode on
* for the "any" device (so you don't have to explicitly
* disable it in programs such as tcpdump).
*/
if (!is_any_device && handle->opt.promisc) {
memset(&mr, 0, sizeof(mr));
mr.mr_ifindex = handlep->ifindex;
mr.mr_type = PACKET_MR_PROMISC;
if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
&mr, sizeof(mr)) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "setsockopt (PACKET_ADD_MEMBERSHIP)");
close(sock_fd);
return PCAP_ERROR;
}
}
/*
* Enable auxiliary data and reserve room for reconstructing
* VLAN headers.
*
* XXX - is enabling auxiliary data necessary, now that we
* only support memory-mapped capture? The kernel's memory-mapped
* capture code doesn't seem to check whether auxiliary data
* is enabled, it seems to provide it whether it is or not.
*/
val = 1;
if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val,
sizeof(val)) == -1 && errno != ENOPROTOOPT) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "setsockopt (PACKET_AUXDATA)");
close(sock_fd);
return PCAP_ERROR;
}
handle->offset += VLAN_TAG_LEN;
/*
* If we're in cooked mode, make the snapshot length
* large enough to hold a "cooked mode" header plus
* 1 byte of packet data (so we don't pass a byte
* count of 0 to "recvfrom()").
* XXX - we don't know whether this will be DLT_LINUX_SLL
* or DLT_LINUX_SLL2, so make sure it's big enough for
* a DLT_LINUX_SLL2 "cooked mode" header; a snapshot length
* that small is silly anyway.
*/
if (handlep->cooked) {
if (handle->snapshot < SLL2_HDR_LEN + 1)
handle->snapshot = SLL2_HDR_LEN + 1;
}
handle->bufsize = handle->snapshot;
/*
* Set the offset at which to insert VLAN tags.
*/
set_vlan_offset(handle);
if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) {
int nsec_tstamps = 1;
if (setsockopt(sock_fd, SOL_SOCKET, SO_TIMESTAMPNS, &nsec_tstamps, sizeof(nsec_tstamps)) < 0) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "setsockopt: unable to set SO_TIMESTAMPNS");
close(sock_fd);
return PCAP_ERROR;
}
}
/*
* We've succeeded. Save the socket FD in the pcap structure.
*/
handle->fd = sock_fd;
#if defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT)
/*
* Can we generate special code for VLAN checks?
* (XXX - what if we need the special code but it's not supported
* by the OS? Is that possible?)
*/
if (getsockopt(sock_fd, SOL_SOCKET, SO_BPF_EXTENSIONS,
&bpf_extensions, &len) == 0) {
if (bpf_extensions >= SKF_AD_VLAN_TAG_PRESENT) {
/*
* Yes, we can. Request that we do so.
*/
handle->bpf_codegen_flags |= BPF_SPECIAL_VLAN_HANDLING;
}
}
#endif /* defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) */
return status;
}
/*
* Attempt to setup memory-mapped access.
*
* On success, returns 0 if there are no warnings or a PCAP_WARNING_ code
* if there is a warning.
*
* On error, returns the appropriate error code; if that is PCAP_ERROR,
* sets handle->errbuf to the appropriate message.
*/
static int
setup_mmapped(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
int status;
/*
* Attempt to allocate a buffer to hold the contents of one
* packet, for use by the oneshot callback.
*/
handlep->oneshot_buffer = malloc(handle->snapshot);
if (handlep->oneshot_buffer == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "can't allocate oneshot buffer");
return PCAP_ERROR;
}
if (handle->opt.buffer_size == 0) {
/* by default request 2M for the ring buffer */
handle->opt.buffer_size = 2*1024*1024;
}
status = prepare_tpacket_socket(handle);
if (status == -1) {
free(handlep->oneshot_buffer);
handlep->oneshot_buffer = NULL;
return PCAP_ERROR;
}
status = create_ring(handle);
if (status < 0) {
/*
* Error attempting to enable memory-mapped capture;
* fail. The return value is the status to return.
*/
free(handlep->oneshot_buffer);
handlep->oneshot_buffer = NULL;
return status;
}
/*
* Success. status has been set either to 0 if there are no
* warnings or to a PCAP_WARNING_ value if there is a warning.
*
* handle->offset is used to get the current position into the rx ring.
* handle->cc is used to store the ring size.
*/
/*
* Set the timeout to use in poll() before returning.
*/
set_poll_timeout(handlep);
return status;
}
/*
* Attempt to set the socket to the specified version of the memory-mapped
* header.
*
* Return 0 if we succeed; return 1 if we fail because that version isn't
* supported; return -1 on any other error, and set handle->errbuf.
*/
static int
init_tpacket(pcap_t *handle, int version, const char *version_str)
{
struct pcap_linux *handlep = handle->priv;
int val = version;
socklen_t len = sizeof(val);
/*
* Probe whether kernel supports the specified TPACKET version;
* this also gets the length of the header for that version.
*
* This socket option was introduced in 2.6.27, which was
* also the first release with TPACKET_V2 support.
*/
if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) {
if (errno == EINVAL) {
/*
* EINVAL means this specific version of TPACKET
* is not supported. Tell the caller they can try
* with a different one; if they've run out of
* others to try, let them set the error message
* appropriately.
*/
return 1;
}
/*
* All other errors are fatal.
*/
if (errno == ENOPROTOOPT) {
/*
* PACKET_HDRLEN isn't supported, which means
* that memory-mapped capture isn't supported.
* Indicate that in the message.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Kernel doesn't support memory-mapped capture; a 2.6.27 or later 2.x kernel is required, with CONFIG_PACKET_MMAP specified for 2.x kernels");
} else {
/*
* Some unexpected error.
*/
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "can't get %s header len on packet socket",
version_str);
}
return -1;
}
handlep->tp_hdrlen = val;
val = version;
if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val,
sizeof(val)) < 0) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "can't activate %s on packet socket", version_str);
return -1;
}
handlep->tp_version = version;
return 0;
}
/*
* Attempt to set the socket to version 3 of the memory-mapped header and,
* if that fails because version 3 isn't supported, attempt to fall
* back to version 2. If version 2 isn't supported, just fail.
*
* Return 0 if we succeed and -1 on any other error, and set handle->errbuf.
*/
static int
prepare_tpacket_socket(pcap_t *handle)
{
int ret;
#ifdef HAVE_TPACKET3
/*
* Try setting the version to TPACKET_V3.
*
* The only mode in which buffering is done on PF_PACKET
* sockets, so that packets might not be delivered
* immediately, is TPACKET_V3 mode.
*
* The buffering cannot be disabled in that mode, so
* if the user has requested immediate mode, we don't
* use TPACKET_V3.
*/
if (!handle->opt.immediate) {
ret = init_tpacket(handle, TPACKET_V3, "TPACKET_V3");
if (ret == 0) {
/*
* Success.
*/
return 0;
}
if (ret == -1) {
/*
* We failed for some reason other than "the
* kernel doesn't support TPACKET_V3".
*/
return -1;
}
/*
* This means it returned 1, which means "the kernel
* doesn't support TPACKET_V3"; try TPACKET_V2.
*/
}
#endif /* HAVE_TPACKET3 */
/*
* Try setting the version to TPACKET_V2.
*/
ret = init_tpacket(handle, TPACKET_V2, "TPACKET_V2");
if (ret == 0) {
/*
* Success.
*/
return 0;
}
if (ret == 1) {
/*
* OK, the kernel supports memory-mapped capture, but
* not TPACKET_V2. Set the error message appropriately.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Kernel doesn't support TPACKET_V2; a 2.6.27 or later kernel is required");
}
/*
* We failed.
*/
return -1;
}
#define MAX(a,b) ((a)>(b)?(a):(b))
/*
* Attempt to set up memory-mapped access.
*
* On success, returns 0 if there are no warnings or to a PCAP_WARNING_ code
* if there is a warning.
*
* On error, returns the appropriate error code; if that is PCAP_ERROR,
* sets handle->errbuf to the appropriate message.
*/
static int
create_ring(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
unsigned i, j, frames_per_block;
#ifdef HAVE_TPACKET3
/*
* For sockets using TPACKET_V2, the extra stuff at the end of a
* struct tpacket_req3 will be ignored, so this is OK even for
* those sockets.
*/
struct tpacket_req3 req;
#else
struct tpacket_req req;
#endif
socklen_t len;
unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff;
unsigned int frame_size;
int status;
/*
* Start out assuming no warnings.
*/
status = 0;
/*
* Reserve space for VLAN tag reconstruction.
*/
tp_reserve = VLAN_TAG_LEN;
/*
* If we're capturing in cooked mode, reserve space for
* a DLT_LINUX_SLL2 header; we don't know yet whether
* we'll be using DLT_LINUX_SLL or DLT_LINUX_SLL2, as
* that can be changed on an open device, so we reserve
* space for the larger of the two.
*
* XXX - we assume that the kernel is still adding
* 16 bytes of extra space, so we subtract 16 from
* SLL2_HDR_LEN to get the additional space needed.
* (Are they doing that for DLT_LINUX_SLL, the link-
* layer header for which is 16 bytes?)
*
* XXX - should we use TPACKET_ALIGN(SLL2_HDR_LEN - 16)?
*/
if (handlep->cooked)
tp_reserve += SLL2_HDR_LEN - 16;
/*
* Try to request that amount of reserve space.
* This must be done before creating the ring buffer.
*/
len = sizeof(tp_reserve);
if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE,
&tp_reserve, len) < 0) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"setsockopt (PACKET_RESERVE)");
return PCAP_ERROR;
}
switch (handlep->tp_version) {
case TPACKET_V2:
/* Note that with large snapshot length (say 256K, which is
* the default for recent versions of tcpdump, Wireshark,
* TShark, dumpcap or 64K, the value that "-s 0" has given for
* a long time with tcpdump), if we use the snapshot
* length to calculate the frame length, only a few frames
* will be available in the ring even with pretty
* large ring size (and a lot of memory will be unused).
*
* Ideally, we should choose a frame length based on the
* minimum of the specified snapshot length and the maximum
* packet size. That's not as easy as it sounds; consider,
* for example, an 802.11 interface in monitor mode, where
* the frame would include a radiotap header, where the
* maximum radiotap header length is device-dependent.
*
* So, for now, we just do this for Ethernet devices, where
* there's no metadata header, and the link-layer header is
* fixed length. We can get the maximum packet size by
* adding 18, the Ethernet header length plus the CRC length
* (just in case we happen to get the CRC in the packet), to
* the MTU of the interface; we fetch the MTU in the hopes
* that it reflects support for jumbo frames. (Even if the
* interface is just being used for passive snooping, the
* driver might set the size of buffers in the receive ring
* based on the MTU, so that the MTU limits the maximum size
* of packets that we can receive.)
*
* If segmentation/fragmentation or receive offload are
* enabled, we can get reassembled/aggregated packets larger
* than MTU, but bounded to 65535 plus the Ethernet overhead,
* due to kernel and protocol constraints */
frame_size = handle->snapshot;
if (handle->linktype == DLT_EN10MB) {
unsigned int max_frame_len;
int mtu;
int offload;
mtu = iface_get_mtu(handle->fd, handle->opt.device,
handle->errbuf);
if (mtu == -1)
return PCAP_ERROR;
offload = iface_get_offload(handle);
if (offload == -1)
return PCAP_ERROR;
if (offload)
max_frame_len = MAX(mtu, 65535);
else
max_frame_len = mtu;
max_frame_len += 18;
if (frame_size > max_frame_len)
frame_size = max_frame_len;
}
/* NOTE: calculus matching those in tpacket_rcv()
* in linux-2.6/net/packet/af_packet.c
*/
len = sizeof(sk_type);
if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type,
&len) < 0) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "getsockopt (SO_TYPE)");
return PCAP_ERROR;
}
maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE;
/* XXX: in the kernel maclen is calculated from
* LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len
* in: packet_snd() in linux-2.6/net/packet/af_packet.c
* then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c
* then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c
* but I see no way to get those sizes in userspace,
* like for instance with an ifreq ioctl();
* the best thing I've found so far is MAX_HEADER in
* the kernel part of linux-2.6/include/linux/netdevice.h
* which goes up to 128+48=176; since pcap-linux.c
* defines a MAX_LINKHEADER_SIZE of 256 which is
* greater than that, let's use it.. maybe is it even
* large enough to directly replace macoff..
*/
tp_hdrlen = TPACKET_ALIGN(handlep->tp_hdrlen) + sizeof(struct sockaddr_ll) ;
netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve;
/* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN
* of netoff, which contradicts
* linux-2.6/Documentation/networking/packet_mmap.txt
* documenting that:
* "- Gap, chosen so that packet data (Start+tp_net)
* aligns to TPACKET_ALIGNMENT=16"
*/
/* NOTE: in linux-2.6/include/linux/skbuff.h:
* "CPUs often take a performance hit
* when accessing unaligned memory locations"
*/
macoff = netoff - maclen;
req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size);
/*
* Round the buffer size up to a multiple of the
* frame size (rather than rounding down, which
* would give a buffer smaller than our caller asked
* for, and possibly give zero frames if the requested
* buffer size is too small for one frame).
*/
req.tp_frame_nr = (handle->opt.buffer_size + req.tp_frame_size - 1)/req.tp_frame_size;
break;
#ifdef HAVE_TPACKET3
case TPACKET_V3:
/* The "frames" for this are actually buffers that
* contain multiple variable-sized frames.
*
* We pick a "frame" size of MAXIMUM_SNAPLEN to leave
* enough room for at least one reasonably-sized packet
* in the "frame". */
req.tp_frame_size = MAXIMUM_SNAPLEN;
/*
* Round the buffer size up to a multiple of the
* "frame" size (rather than rounding down, which
* would give a buffer smaller than our caller asked
* for, and possibly give zero "frames" if the requested
* buffer size is too small for one "frame").
*/
req.tp_frame_nr = (handle->opt.buffer_size + req.tp_frame_size - 1)/req.tp_frame_size;
break;
#endif
default:
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Internal error: unknown TPACKET_ value %u",
handlep->tp_version);
return PCAP_ERROR;
}
/* compute the minimum block size that will handle this frame.
* The block has to be page size aligned.
* The max block size allowed by the kernel is arch-dependent and
* it's not explicitly checked here. */
req.tp_block_size = getpagesize();
while (req.tp_block_size < req.tp_frame_size)
req.tp_block_size <<= 1;
frames_per_block = req.tp_block_size/req.tp_frame_size;
/*
* PACKET_TIMESTAMP was added after linux/net_tstamp.h was,
* so we check for PACKET_TIMESTAMP. We check for
* linux/net_tstamp.h just in case a system somehow has
* PACKET_TIMESTAMP but not linux/net_tstamp.h; that might
* be unnecessary.
*
* SIOCSHWTSTAMP was introduced in the patch that introduced
* linux/net_tstamp.h, so we don't bother checking whether
* SIOCSHWTSTAMP is defined (if your Linux system has
* linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your
* Linux system is badly broken).
*/
#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
/*
* If we were told to do so, ask the kernel and the driver
* to use hardware timestamps.
*
* Hardware timestamps are only supported with mmapped
* captures.
*/
if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER ||
handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) {
struct hwtstamp_config hwconfig;
struct ifreq ifr;
int timesource;
/*
* Ask for hardware time stamps on all packets,
* including transmitted packets.
*/
memset(&hwconfig, 0, sizeof(hwconfig));
hwconfig.tx_type = HWTSTAMP_TX_ON;
hwconfig.rx_filter = HWTSTAMP_FILTER_ALL;
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, handle->opt.device, sizeof(ifr.ifr_name));
ifr.ifr_data = (void *)&hwconfig;
/*
* This may require CAP_NET_ADMIN.
*/
if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) {
switch (errno) {
case EPERM:
/*
* Treat this as an error, as the
* user should try to run this
* with the appropriate privileges -
* and, if they can't, shouldn't
* try requesting hardware time stamps.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Attempt to set hardware timestamp failed - CAP_NET_ADMIN may be required");
return PCAP_ERROR_PERM_DENIED;
case EOPNOTSUPP:
case ERANGE:
/*
* Treat this as a warning, as the
* only way to fix the warning is to
* get an adapter that supports hardware
* time stamps for *all* packets.
* (ERANGE means "we support hardware
* time stamps, but for packets matching
* that particular filter", so it means
* "we don't support hardware time stamps
* for all incoming packets" here.)
*
* We'll just fall back on the standard
* host time stamps.
*/
status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP;
break;
default:
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"SIOCSHWTSTAMP failed");
return PCAP_ERROR;
}
} else {
/*
* Well, that worked. Now specify the type of
* hardware time stamp we want for this
* socket.
*/
if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) {
/*
* Hardware timestamp, synchronized
* with the system clock.
*/
timesource = SOF_TIMESTAMPING_SYS_HARDWARE;
} else {
/*
* PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware
* timestamp, not synchronized with the
* system clock.
*/
timesource = SOF_TIMESTAMPING_RAW_HARDWARE;
}
if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP,
(void *)×ource, sizeof(timesource))) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't set PACKET_TIMESTAMP");
return PCAP_ERROR;
}
}
}
#endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */
/* ask the kernel to create the ring */
retry:
req.tp_block_nr = req.tp_frame_nr / frames_per_block;
/* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */
req.tp_frame_nr = req.tp_block_nr * frames_per_block;
#ifdef HAVE_TPACKET3
/* timeout value to retire block - use the configured buffering timeout, or default if <0. */
if (handlep->timeout > 0) {
/* Use the user specified timeout as the block timeout */
req.tp_retire_blk_tov = handlep->timeout;
} else if (handlep->timeout == 0) {
/*
* In pcap, this means "infinite timeout"; TPACKET_V3
* doesn't support that, so just set it to UINT_MAX
* milliseconds. In the TPACKET_V3 loop, if the
* timeout is 0, and we haven't yet seen any packets,
* and we block and still don't have any packets, we
* keep blocking until we do.
*/
req.tp_retire_blk_tov = UINT_MAX;
} else {
/*
* XXX - this is not valid; use 0, meaning "have the
* kernel pick a default", for now.
*/
req.tp_retire_blk_tov = 0;
}
/* private data not used */
req.tp_sizeof_priv = 0;
/* Rx ring - feature request bits - none (rxhash will not be filled) */
req.tp_feature_req_word = 0;
#endif
if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
(void *) &req, sizeof(req))) {
if ((errno == ENOMEM) && (req.tp_block_nr > 1)) {
/*
* Memory failure; try to reduce the requested ring
* size.
*
* We used to reduce this by half -- do 5% instead.
* That may result in more iterations and a longer
* startup, but the user will be much happier with
* the resulting buffer size.
*/
if (req.tp_frame_nr < 20)
req.tp_frame_nr -= 1;
else
req.tp_frame_nr -= req.tp_frame_nr/20;
goto retry;
}
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "can't create rx ring on packet socket");
return PCAP_ERROR;
}
/* memory map the rx ring */
handlep->mmapbuflen = req.tp_block_nr * req.tp_block_size;
handlep->mmapbuf = mmap(0, handlep->mmapbuflen,
PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0);
if (handlep->mmapbuf == MAP_FAILED) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "can't mmap rx ring");
/* clear the allocated ring on error*/
destroy_ring(handle);
return PCAP_ERROR;
}
/* allocate a ring for each frame header pointer*/
handle->cc = req.tp_frame_nr;
handle->buffer = malloc(handle->cc * sizeof(union thdr *));
if (!handle->buffer) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "can't allocate ring of frame headers");
destroy_ring(handle);
return PCAP_ERROR;
}
/* fill the header ring with proper frame ptr*/
handle->offset = 0;
for (i=0; i<req.tp_block_nr; ++i) {
u_char *base = &handlep->mmapbuf[i*req.tp_block_size];
for (j=0; j<frames_per_block; ++j, ++handle->offset) {
RING_GET_CURRENT_FRAME(handle) = base;
base += req.tp_frame_size;
}
}
handle->bufsize = req.tp_frame_size;
handle->offset = 0;
return status;
}
/* free all ring related resources*/
static void
destroy_ring(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
/*
* Tell the kernel to destroy the ring.
* We don't check for setsockopt failure, as 1) we can't recover
* from an error and 2) we might not yet have set it up in the
* first place.
*/
struct tpacket_req req;
memset(&req, 0, sizeof(req));
(void)setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
(void *) &req, sizeof(req));
/* if ring is mapped, unmap it*/
if (handlep->mmapbuf) {
/* do not test for mmap failure, as we can't recover from any error */
(void)munmap(handlep->mmapbuf, handlep->mmapbuflen);
handlep->mmapbuf = NULL;
}
}
/*
* Special one-shot callback, used for pcap_next() and pcap_next_ex(),
* for Linux mmapped capture.
*
* The problem is that pcap_next() and pcap_next_ex() expect the packet
* data handed to the callback to be valid after the callback returns,
* but pcap_read_linux_mmap() has to release that packet as soon as
* the callback returns (otherwise, the kernel thinks there's still
* at least one unprocessed packet available in the ring, so a select()
* will immediately return indicating that there's data to process), so,
* in the callback, we have to make a copy of the packet.
*
* Yes, this means that, if the capture is using the ring buffer, using
* pcap_next() or pcap_next_ex() requires more copies than using
* pcap_loop() or pcap_dispatch(). If that bothers you, don't use
* pcap_next() or pcap_next_ex().
*/
static void
pcapint_oneshot_linux(u_char *user, const struct pcap_pkthdr *h,
const u_char *bytes)
{
struct oneshot_userdata *sp = (struct oneshot_userdata *)user;
pcap_t *handle = sp->pd;
struct pcap_linux *handlep = handle->priv;
*sp->hdr = *h;
memcpy(handlep->oneshot_buffer, bytes, h->caplen);
*sp->pkt = handlep->oneshot_buffer;
}
static int
pcap_getnonblock_linux(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
/* use negative value of timeout to indicate non blocking ops */
return (handlep->timeout<0);
}
static int
pcap_setnonblock_linux(pcap_t *handle, int nonblock)
{
struct pcap_linux *handlep = handle->priv;
/*
* Set the file descriptor to the requested mode, as we use
* it for sending packets.
*/
if (pcapint_setnonblock_fd(handle, nonblock) == -1)
return -1;
/*
* Map each value to their corresponding negation to
* preserve the timeout value provided with pcap_set_timeout.
*/
if (nonblock) {
/*
* We're setting the mode to non-blocking mode.
*/
if (handlep->timeout >= 0) {
/*
* Indicate that we're switching to
* non-blocking mode.
*/
handlep->timeout = ~handlep->timeout;
}
if (handlep->poll_breakloop_fd != -1) {
/* Close the eventfd; we do not need it in nonblock mode. */
close(handlep->poll_breakloop_fd);
handlep->poll_breakloop_fd = -1;
}
} else {
/*
* We're setting the mode to blocking mode.
*/
if (handlep->poll_breakloop_fd == -1) {
/* If we did not have an eventfd, open one now that we are blocking. */
if ( ( handlep->poll_breakloop_fd = eventfd(0, EFD_NONBLOCK) ) == -1 ) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"could not open eventfd");
return -1;
}
}
if (handlep->timeout < 0) {
handlep->timeout = ~handlep->timeout;
}
}
/* Update the timeout to use in poll(). */
set_poll_timeout(handlep);
return 0;
}
/*
* Get the status field of the ring buffer frame at a specified offset.
*/
static inline u_int
pcap_get_ring_frame_status(pcap_t *handle, int offset)
{
struct pcap_linux *handlep = handle->priv;
union thdr h;
h.raw = RING_GET_FRAME_AT(handle, offset);
switch (handlep->tp_version) {
case TPACKET_V2:
return __atomic_load_n(&h.h2->tp_status, __ATOMIC_ACQUIRE);
break;
#ifdef HAVE_TPACKET3
case TPACKET_V3:
return __atomic_load_n(&h.h3->hdr.bh1.block_status, __ATOMIC_ACQUIRE);
break;
#endif
}
/* This should not happen. */
return 0;
}
/*
* Block waiting for frames to be available.
*/
static int pcap_wait_for_frames_mmap(pcap_t *handle)
{
struct pcap_linux *handlep = handle->priv;
int timeout;
struct ifreq ifr;
int ret;
struct pollfd pollinfo[2];
int numpollinfo;
pollinfo[0].fd = handle->fd;
pollinfo[0].events = POLLIN;
if ( handlep->poll_breakloop_fd == -1 ) {
numpollinfo = 1;
pollinfo[1].revents = 0;
/*
* We set pollinfo[1].revents to zero, even though
* numpollinfo = 1 meaning that poll() doesn't see
* pollinfo[1], so that we do not have to add a
* conditional of numpollinfo > 1 below when we
* test pollinfo[1].revents.
*/
} else {
pollinfo[1].fd = handlep->poll_breakloop_fd;
pollinfo[1].events = POLLIN;
numpollinfo = 2;
}
/*
* Keep polling until we either get some packets to read, see
* that we got told to break out of the loop, get a fatal error,
* or discover that the device went away.
*
* In non-blocking mode, we must still do one poll() to catch
* any pending error indications, but the poll() has a timeout
* of 0, so that it doesn't block, and we quit after that one
* poll().
*
* If we've seen an ENETDOWN, it might be the first indication
* that the device went away, or it might just be that it was
* configured down. Unfortunately, there's no guarantee that
* the device has actually been removed as an interface, because:
*
* 1) if, as appears to be the case at least some of the time,
* the PF_PACKET socket code first gets a NETDEV_DOWN indication
* for the device and then gets a NETDEV_UNREGISTER indication
* for it, the first indication will cause a wakeup with ENETDOWN
* but won't set the packet socket's field for the interface index
* to -1, and the second indication won't cause a wakeup (because
* the first indication also caused the protocol hook to be
* unregistered) but will set the packet socket's field for the
* interface index to -1;
*
* 2) even if just a NETDEV_UNREGISTER indication is registered,
* the packet socket's field for the interface index only gets
* set to -1 after the wakeup, so there's a small but non-zero
* risk that a thread blocked waiting for the wakeup will get
* to the "fetch the socket name" code before the interface index
* gets set to -1, so it'll get the old interface index.
*
* Therefore, if we got an ENETDOWN and haven't seen a packet
* since then, we assume that we might be waiting for the interface
* to disappear, and poll with a timeout to try again in a short
* period of time. If we *do* see a packet, the interface has
* come back up again, and is *definitely* still there, so we
* don't need to poll.
*/
for (;;) {
/*
* Yes, we do this even in non-blocking mode, as it's
* the only way to get error indications from a
* tpacket socket.
*
* The timeout is 0 in non-blocking mode, so poll()
* returns immediately.
*/
timeout = handlep->poll_timeout;
/*
* If we got an ENETDOWN and haven't gotten an indication
* that the device has gone away or that the device is up,
* we don't yet know for certain whether the device has
* gone away or not, do a poll() with a 1-millisecond timeout,
* as we have to poll indefinitely for "device went away"
* indications until we either get one or see that the
* device is up.
*/
if (handlep->netdown) {
if (timeout != 0)
timeout = 1;
}
ret = poll(pollinfo, numpollinfo, timeout);
if (ret < 0) {
/*
* Error. If it's not EINTR, report it.
*/
if (errno != EINTR) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't poll on packet socket");
return PCAP_ERROR;
}
/*
* It's EINTR; if we were told to break out of
* the loop, do so.
*/
if (handle->break_loop) {
handle->break_loop = 0;
return PCAP_ERROR_BREAK;
}
} else if (ret > 0) {
/*
* OK, some descriptor is ready.
* Check the socket descriptor first.
*
* As I read the Linux man page, pollinfo[0].revents
* will either be POLLIN, POLLERR, POLLHUP, or POLLNVAL.
*/
if (pollinfo[0].revents == POLLIN) {
/*
* OK, we may have packets to
* read.
*/
break;
}
if (pollinfo[0].revents != 0) {
/*
* There's some indication other than
* "you can read on this descriptor" on
* the descriptor.
*/
if (pollinfo[0].revents & POLLNVAL) {
snprintf(handle->errbuf,
PCAP_ERRBUF_SIZE,
"Invalid polling request on packet socket");
return PCAP_ERROR;
}
if (pollinfo[0].revents & (POLLHUP | POLLRDHUP)) {
snprintf(handle->errbuf,
PCAP_ERRBUF_SIZE,
"Hangup on packet socket");
return PCAP_ERROR;
}
if (pollinfo[0].revents & POLLERR) {
/*
* Get the error.
*/
int err;
socklen_t errlen;
errlen = sizeof(err);
if (getsockopt(handle->fd, SOL_SOCKET,
SO_ERROR, &err, &errlen) == -1) {
/*
* The call *itself* returned
* an error; make *that*
* the error.
*/
err = errno;
}
/*
* OK, we have the error.
*/
if (err == ENETDOWN) {
/*
* The device on which we're
* capturing went away or the
* interface was taken down.
*
* We don't know for certain
* which happened, and the
* next poll() may indicate
* that there are packets
* to be read, so just set
* a flag to get us to do
* checks later, and set
* the required select
* timeout to 1 millisecond
* so that event loops that
* check our socket descriptor
* also time out so that
* they can call us and we
* can do the checks.
*/
handlep->netdown = 1;
handle->required_select_timeout = &netdown_timeout;
} else if (err == 0) {
/*
* This shouldn't happen, so
* report a special indication
* that it did.
*/
snprintf(handle->errbuf,
PCAP_ERRBUF_SIZE,
"Error condition on packet socket: Reported error was 0");
return PCAP_ERROR;
} else {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE,
err,
"Error condition on packet socket");
return PCAP_ERROR;
}
}
}
/*
* Now check the event device.
*/
if (pollinfo[1].revents & POLLIN) {
ssize_t nread;
uint64_t value;
/*
* This should never fail, but, just
* in case....
*/
nread = read(handlep->poll_breakloop_fd, &value,
sizeof(value));
if (nread == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE,
errno,
"Error reading from event FD");
return PCAP_ERROR;
}
/*
* According to the Linux read(2) man
* page, read() will transfer at most
* 2^31-1 bytes, so the return value is
* either -1 or a value between 0
* and 2^31-1, so it's non-negative.
*
* Cast it to size_t to squelch
* warnings from the compiler; add this
* comment to squelch warnings from
* humans reading the code. :-)
*
* Don't treat an EOF as an error, but
* *do* treat a short read as an error;
* that "shouldn't happen", but....
*/
if (nread != 0 &&
(size_t)nread < sizeof(value)) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Short read from event FD: expected %zu, got %zd",
sizeof(value), nread);
return PCAP_ERROR;
}
/*
* This event gets signaled by a
* pcap_breakloop() call; if we were told
* to break out of the loop, do so.
*/
if (handle->break_loop) {
handle->break_loop = 0;
return PCAP_ERROR_BREAK;
}
}
}
/*
* Either:
*
* 1) we got neither an error from poll() nor any
* readable descriptors, in which case there
* are no packets waiting to read
*
* or
*
* 2) We got readable descriptors but the PF_PACKET
* socket wasn't one of them, in which case there
* are no packets waiting to read
*
* so, if we got an ENETDOWN, we've drained whatever
* packets were available to read at the point of the
* ENETDOWN.
*
* So, if we got an ENETDOWN and haven't gotten an indication
* that the device has gone away or that the device is up,
* we don't yet know for certain whether the device has
* gone away or not, check whether the device exists and is
* up.
*/
if (handlep->netdown) {
if (!device_still_exists(handle)) {
/*
* The device doesn't exist any more;
* report that.
*
* XXX - we should really return an
* appropriate error for that, but
* pcap_dispatch() etc. aren't documented
* as having error returns other than
* PCAP_ERROR or PCAP_ERROR_BREAK.
*/
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"The interface disappeared");
return PCAP_ERROR;
}
/*
* The device still exists; try to see if it's up.
*/
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, handlep->device,
sizeof(ifr.ifr_name));
if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
if (errno == ENXIO || errno == ENODEV) {
/*
* OK, *now* it's gone.
*
* XXX - see above comment.
*/
snprintf(handle->errbuf,
PCAP_ERRBUF_SIZE,
"The interface disappeared");
return PCAP_ERROR;
} else {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"%s: Can't get flags",
handlep->device);
return PCAP_ERROR;
}
}
if (ifr.ifr_flags & IFF_UP) {
/*
* It's up, so it definitely still exists.
* Cancel the ENETDOWN indication - we
* presumably got it due to the interface
* going down rather than the device going
* away - and revert to "no required select
* timeout.
*/
handlep->netdown = 0;
handle->required_select_timeout = NULL;
}
}
/*
* If we're in non-blocking mode, just quit now, rather
* than spinning in a loop doing poll()s that immediately
* time out if there's no indication on any descriptor.
*/
if (handlep->poll_timeout == 0)
break;
}
return 0;
}
/* handle a single memory mapped packet */
static int pcap_handle_packet_mmap(
pcap_t *handle,
pcap_handler callback,
u_char *user,
unsigned char *frame,
unsigned int tp_len,
unsigned int tp_mac,
unsigned int tp_snaplen,
unsigned int tp_sec,
unsigned int tp_usec,
int tp_vlan_tci_valid,
__u16 tp_vlan_tci,
__u16 tp_vlan_tpid)
{
struct pcap_linux *handlep = handle->priv;
unsigned char *bp;
struct sockaddr_ll *sll;
struct pcap_pkthdr pcaphdr;
unsigned int snaplen = tp_snaplen;
struct utsname utsname;
/* perform sanity check on internal offset. */
if (tp_mac + tp_snaplen > handle->bufsize) {
/*
* Report some system information as a debugging aid.
*/
if (uname(&utsname) != -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"corrupted frame on kernel ring mac "
"offset %u + caplen %u > frame len %d "
"(kernel %.32s version %s, machine %.16s)",
tp_mac, tp_snaplen, handle->bufsize,
utsname.release, utsname.version,
utsname.machine);
} else {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"corrupted frame on kernel ring mac "
"offset %u + caplen %u > frame len %d",
tp_mac, tp_snaplen, handle->bufsize);
}
return -1;
}
/* run filter on received packet
* If the kernel filtering is enabled we need to run the
* filter until all the frames present into the ring
* at filter creation time are processed.
* In this case, blocks_to_filter_in_userland is used
* as a counter for the packet we need to filter.
* Note: alternatively it could be possible to stop applying
* the filter when the ring became empty, but it can possibly
* happen a lot later... */
bp = frame + tp_mac;
/* if required build in place the sll header*/
sll = (void *)(frame + TPACKET_ALIGN(handlep->tp_hdrlen));
if (handlep->cooked) {
if (handle->linktype == DLT_LINUX_SLL2) {
struct sll2_header *hdrp;
/*
* The kernel should have left us with enough
* space for an sll header; back up the packet
* data pointer into that space, as that'll be
* the beginning of the packet we pass to the
* callback.
*/
bp -= SLL2_HDR_LEN;
/*
* Let's make sure that's past the end of
* the tpacket header, i.e. >=
* ((u_char *)thdr + TPACKET_HDRLEN), so we
* don't step on the header when we construct
* the sll header.
*/
if (bp < (u_char *)frame +
TPACKET_ALIGN(handlep->tp_hdrlen) +
sizeof(struct sockaddr_ll)) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"cooked-mode frame doesn't have room for sll header");
return -1;
}
/*
* OK, that worked; construct the sll header.
*/
hdrp = (struct sll2_header *)bp;
hdrp->sll2_protocol = sll->sll_protocol;
hdrp->sll2_reserved_mbz = 0;
hdrp->sll2_if_index = htonl(sll->sll_ifindex);
hdrp->sll2_hatype = htons(sll->sll_hatype);
hdrp->sll2_pkttype = sll->sll_pkttype;
hdrp->sll2_halen = sll->sll_halen;
memcpy(hdrp->sll2_addr, sll->sll_addr, SLL_ADDRLEN);
snaplen += sizeof(struct sll2_header);
} else {
struct sll_header *hdrp;
/*
* The kernel should have left us with enough
* space for an sll header; back up the packet
* data pointer into that space, as that'll be
* the beginning of the packet we pass to the
* callback.
*/
bp -= SLL_HDR_LEN;
/*
* Let's make sure that's past the end of
* the tpacket header, i.e. >=
* ((u_char *)thdr + TPACKET_HDRLEN), so we
* don't step on the header when we construct
* the sll header.
*/
if (bp < (u_char *)frame +
TPACKET_ALIGN(handlep->tp_hdrlen) +
sizeof(struct sockaddr_ll)) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"cooked-mode frame doesn't have room for sll header");
return -1;
}
/*
* OK, that worked; construct the sll header.
*/
hdrp = (struct sll_header *)bp;
hdrp->sll_pkttype = htons(sll->sll_pkttype);
hdrp->sll_hatype = htons(sll->sll_hatype);
hdrp->sll_halen = htons(sll->sll_halen);
memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN);
hdrp->sll_protocol = sll->sll_protocol;
snaplen += sizeof(struct sll_header);
}
} else {
/*
* If this is a packet from a CAN device, so that
* sll->sll_hatype is ARPHRD_CAN, then, as we're
* not capturing in cooked mode, its link-layer
* type is DLT_CAN_SOCKETCAN. Fix up the header
* provided by the code below us to match what
* DLT_CAN_SOCKETCAN is expected to provide.
*/
if (sll->sll_hatype == ARPHRD_CAN) {
pcap_can_socketcan_hdr *canhdr = (pcap_can_socketcan_hdr *)bp;
uint16_t protocol = ntohs(sll->sll_protocol);
/*
* Check the protocol field from the sll header.
* If it's one of the known CAN protocol types,
* make sure the appropriate flags are set, so
* that a program can tell what type of frame
* it is.
*
* The two flags are:
*
* CANFD_FDF, which is in the fd_flags field
* of the CAN classic/CAN FD header;
*
* CANXL_XLF, which is in the flags field
* of the CAN XL header, which overlaps
* the payload_length field of the CAN
* classic/CAN FD header.
*/
switch (protocol) {
case LINUX_SLL_P_CAN:
/*
* CAN classic.
*
* Zero out the fd_flags and reserved
* fields, in case they're uninitialized
* crap, and clear the CANXL_XLF bit in
* the payload_length field.
*
* This means that the CANFD_FDF flag isn't
* set in the fd_flags field, and that
* the CANXL_XLF bit isn't set in the
* payload_length field, so this frame
* will appear to be a CAN classic frame.
*/
canhdr->payload_length &= ~CANXL_XLF;
canhdr->fd_flags = 0;
canhdr->reserved1 = 0;
canhdr->reserved2 = 0;
break;
case LINUX_SLL_P_CANFD:
/*
* Set CANFD_FDF in the fd_flags field,
* and clear the CANXL_XLF bit in the
* payload_length field, so this frame
* will appear to be a CAN FD frame.
*/
canhdr->payload_length &= ~CANXL_XLF;
canhdr->fd_flags |= CANFD_FDF;
/*
* Zero out all the unknown bits in fd_flags
* and clear the reserved fields, so that
* a program reading this can assume that
* CANFD_FDF is set because we set it, not
* because some uninitialized crap was
* provided in the fd_flags field.
*
* (At least some LINKTYPE_CAN_SOCKETCAN
* files attached to Wireshark bugs had
* uninitialized junk there, so it does
* happen.)
*
* Update this if Linux adds more flag bits
* to the fd_flags field or uses either of
* the reserved fields for FD frames.
*/
canhdr->fd_flags &= (CANFD_FDF|CANFD_ESI|CANFD_BRS);
canhdr->reserved1 = 0;
canhdr->reserved2 = 0;
break;
case LINUX_SLL_P_CANXL:
/*
* CAN XL frame.
*
* Make sure the CANXL_XLF bit is set in
* the payload_length field, so that
* this frame will appear to be a
* CAN XL frame.
*/
canhdr->payload_length |= CANXL_XLF;
break;
}
/*
* Put multi-byte header fields in a byte-order
*-independent format.
*/
if (canhdr->payload_length & CANXL_XLF) {
/*
* This is a CAN XL frame.
*
* DLT_CAN_SOCKETCAN is specified as having
* the Priority ID/VCID field in big--
* endian byte order, and the payload length
* and Acceptance Field in little-endian byte
* order. but capturing on a CAN device
* provides them in host byte order.
* Convert them to the appropriate byte
* orders.
*
* The reason we put the first field
* into big-endian byte order is that
* older libpcap code, ignorant of
* CAN XL, treated it as the CAN ID
* field and put it into big-endian
* byte order, and we don't want to
* break code that understands CAN XL
* headers, and treats that field as
* being big-endian.
*
* The other fields are put in little-
* endian byte order is that older
* libpcap code, ignorant of CAN XL,
* left those fields alone, and the
* processors on which the CAN XL
* frames were captured are likely
* to be little-endian processors.
*/
pcap_can_socketcan_xl_hdr *canxl_hdr = (pcap_can_socketcan_xl_hdr *)bp;
#if __BYTE_ORDER == __LITTLE_ENDIAN
/*
* We're capturing on a little-endian
* machine, so we put the priority/VCID
* field into big-endian byte order, and
* leave the payload length and acceptance
* field in little-endian byte order.
*/
/* Byte-swap priority/VCID. */
canxl_hdr->priority_vcid = SWAPLONG(canxl_hdr->priority_vcid);
#elif __BYTE_ORDER == __BIG_ENDIAN
/*
* We're capturing on a big-endian
* machine, so we want to leave the
* priority/VCID field alone, and byte-swap
* the payload length and acceptance
* fields to little-endian.
*/
/* Byte-swap the payload length */
canxl_hdr->payload_length = SWAPSHORT(canxl_hdr->payload_length);
/*
* Byte-swap the acceptance field.
*
* XXX - is it just a 4-octet string,
* not in any byte order?
*/
canxl_hdr->acceptance_field = SWAPLONG(canxl_hdr->acceptance_field);
#else
#error "Unknown byte order"
#endif
} else {
/*
* CAN or CAN FD frame.
*
* DLT_CAN_SOCKETCAN is specified as having
* the CAN ID and flags in network byte
* order, but capturing on a CAN device
* provides it in host byte order. Convert
* it to network byte order.
*/
canhdr->can_id = htonl(canhdr->can_id);
}
}
}
if (handlep->filter_in_userland && handle->fcode.bf_insns) {
struct pcap_bpf_aux_data aux_data;
aux_data.vlan_tag_present = tp_vlan_tci_valid;
aux_data.vlan_tag = tp_vlan_tci & 0x0fff;
if (pcapint_filter_with_aux_data(handle->fcode.bf_insns,
bp,
tp_len,
snaplen,
&aux_data) == 0)
return 0;
}
if (!linux_check_direction(handle, sll))
return 0;
/* get required packet info from ring header */
pcaphdr.ts.tv_sec = tp_sec;
pcaphdr.ts.tv_usec = tp_usec;
pcaphdr.caplen = tp_snaplen;
pcaphdr.len = tp_len;
/* if required build in place the sll header*/
if (handlep->cooked) {
/* update packet len */
if (handle->linktype == DLT_LINUX_SLL2) {
pcaphdr.caplen += SLL2_HDR_LEN;
pcaphdr.len += SLL2_HDR_LEN;
} else {
pcaphdr.caplen += SLL_HDR_LEN;
pcaphdr.len += SLL_HDR_LEN;
}
}
if (tp_vlan_tci_valid &&
handlep->vlan_offset != -1 &&
tp_snaplen >= (unsigned int) handlep->vlan_offset)
{
struct vlan_tag *tag;
/*
* Move everything in the header, except the type field,
* down VLAN_TAG_LEN bytes, to allow us to insert the
* VLAN tag between that stuff and the type field.
*/
bp -= VLAN_TAG_LEN;
memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset);
/*
* Now insert the tag.
*/
tag = (struct vlan_tag *)(bp + handlep->vlan_offset);
tag->vlan_tpid = htons(tp_vlan_tpid);
tag->vlan_tci = htons(tp_vlan_tci);
/*
* Add the tag to the packet lengths.
*/
pcaphdr.caplen += VLAN_TAG_LEN;
pcaphdr.len += VLAN_TAG_LEN;
}
/*
* The only way to tell the kernel to cut off the
* packet at a snapshot length is with a filter program;
* if there's no filter program, the kernel won't cut
* the packet off.
*
* Trim the snapshot length to be no longer than the
* specified snapshot length.
*
* XXX - an alternative is to put a filter, consisting
* of a "ret <snaplen>" instruction, on the socket
* in the activate routine, so that the truncation is
* done in the kernel even if nobody specified a filter;
* that means that less buffer space is consumed in
* the memory-mapped buffer.
*/
if (pcaphdr.caplen > (bpf_u_int32)handle->snapshot)
pcaphdr.caplen = handle->snapshot;
/* pass the packet to the user */
callback(user, &pcaphdr, bp);
return 1;
}
static int
pcap_read_linux_mmap_v2(pcap_t *handle, int max_packets, pcap_handler callback,
u_char *user)
{
struct pcap_linux *handlep = handle->priv;
union thdr h;
int pkts = 0;
int ret;
/* wait for frames availability.*/
h.raw = RING_GET_CURRENT_FRAME(handle);
if (!packet_mmap_acquire(h.h2)) {
/*
* The current frame is owned by the kernel; wait for
* a frame to be handed to us.
*/
ret = pcap_wait_for_frames_mmap(handle);
if (ret) {
return ret;
}
}
/*
* This can conceivably process more than INT_MAX packets,
* which would overflow the packet count, causing it either
* to look like a negative number, and thus cause us to
* return a value that looks like an error, or overflow
* back into positive territory, and thus cause us to
* return a too-low count.
*
* Therefore, if the packet count is unlimited, we clip
* it at INT_MAX; this routine is not expected to
* process packets indefinitely, so that's not an issue.
*/
if (PACKET_COUNT_IS_UNLIMITED(max_packets))
max_packets = INT_MAX;
while (pkts < max_packets) {
/*
* Get the current ring buffer frame, and break if
* it's still owned by the kernel.
*/
h.raw = RING_GET_CURRENT_FRAME(handle);
if (!packet_mmap_acquire(h.h2))
break;
ret = pcap_handle_packet_mmap(
handle,
callback,
user,
h.raw,
h.h2->tp_len,
h.h2->tp_mac,
h.h2->tp_snaplen,
h.h2->tp_sec,
handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? h.h2->tp_nsec : h.h2->tp_nsec / 1000,
VLAN_VALID(h.h2, h.h2),
h.h2->tp_vlan_tci,
VLAN_TPID(h.h2, h.h2));
if (ret == 1) {
pkts++;
} else if (ret < 0) {
return ret;
}
/*
* Hand this block back to the kernel, and, if we're
* counting blocks that need to be filtered in userland
* after having been filtered by the kernel, count
* the one we've just processed.
*/
packet_mmap_release(h.h2);
if (handlep->blocks_to_filter_in_userland > 0) {
handlep->blocks_to_filter_in_userland--;
if (handlep->blocks_to_filter_in_userland == 0) {
/*
* No more blocks need to be filtered
* in userland.
*/
handlep->filter_in_userland = 0;
}
}
/* next block */
if (++handle->offset >= handle->cc)
handle->offset = 0;
/* check for break loop condition*/
if (handle->break_loop) {
handle->break_loop = 0;
return PCAP_ERROR_BREAK;
}
}
return pkts;
}
#ifdef HAVE_TPACKET3
static int
pcap_read_linux_mmap_v3(pcap_t *handle, int max_packets, pcap_handler callback,
u_char *user)
{
struct pcap_linux *handlep = handle->priv;
union thdr h;
int pkts = 0;
int ret;
again:
if (handlep->current_packet == NULL) {
/* wait for frames availability.*/
h.raw = RING_GET_CURRENT_FRAME(handle);
if (!packet_mmap_v3_acquire(h.h3)) {
/*
* The current frame is owned by the kernel; wait
* for a frame to be handed to us.
*/
ret = pcap_wait_for_frames_mmap(handle);
if (ret) {
return ret;
}
}
}
h.raw = RING_GET_CURRENT_FRAME(handle);
if (!packet_mmap_v3_acquire(h.h3)) {
if (pkts == 0 && handlep->timeout == 0) {
/* Block until we see a packet. */
goto again;
}
return pkts;
}
/*
* This can conceivably process more than INT_MAX packets,
* which would overflow the packet count, causing it either
* to look like a negative number, and thus cause us to
* return a value that looks like an error, or overflow
* back into positive territory, and thus cause us to
* return a too-low count.
*
* Therefore, if the packet count is unlimited, we clip
* it at INT_MAX; this routine is not expected to
* process packets indefinitely, so that's not an issue.
*/
if (PACKET_COUNT_IS_UNLIMITED(max_packets))
max_packets = INT_MAX;
while (pkts < max_packets) {
int packets_to_read;
if (handlep->current_packet == NULL) {
h.raw = RING_GET_CURRENT_FRAME(handle);
if (!packet_mmap_v3_acquire(h.h3))
break;
handlep->current_packet = h.raw + h.h3->hdr.bh1.offset_to_first_pkt;
handlep->packets_left = h.h3->hdr.bh1.num_pkts;
}
packets_to_read = handlep->packets_left;
if (packets_to_read > (max_packets - pkts)) {
/*
* There are more packets in the buffer than
* the number of packets we have left to
* process to get up to the maximum number
* of packets to process. Only process enough
* of them to get us up to that maximum.
*/
packets_to_read = max_packets - pkts;
}
while (packets_to_read-- && !handle->break_loop) {
struct tpacket3_hdr* tp3_hdr = (struct tpacket3_hdr*) handlep->current_packet;
ret = pcap_handle_packet_mmap(
handle,
callback,
user,
handlep->current_packet,
tp3_hdr->tp_len,
tp3_hdr->tp_mac,
tp3_hdr->tp_snaplen,
tp3_hdr->tp_sec,
handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? tp3_hdr->tp_nsec : tp3_hdr->tp_nsec / 1000,
VLAN_VALID(tp3_hdr, &tp3_hdr->hv1),
tp3_hdr->hv1.tp_vlan_tci,
VLAN_TPID(tp3_hdr, &tp3_hdr->hv1));
if (ret == 1) {
pkts++;
} else if (ret < 0) {
handlep->current_packet = NULL;
return ret;
}
handlep->current_packet += tp3_hdr->tp_next_offset;
handlep->packets_left--;
}
if (handlep->packets_left <= 0) {
/*
* Hand this block back to the kernel, and, if
* we're counting blocks that need to be
* filtered in userland after having been
* filtered by the kernel, count the one we've
* just processed.
*/
packet_mmap_v3_release(h.h3);
if (handlep->blocks_to_filter_in_userland > 0) {
handlep->blocks_to_filter_in_userland--;
if (handlep->blocks_to_filter_in_userland == 0) {
/*
* No more blocks need to be filtered
* in userland.
*/
handlep->filter_in_userland = 0;
}
}
/* next block */
if (++handle->offset >= handle->cc)
handle->offset = 0;
handlep->current_packet = NULL;
}
/* check for break loop condition*/
if (handle->break_loop) {
handle->break_loop = 0;
return PCAP_ERROR_BREAK;
}
}
if (pkts == 0 && handlep->timeout == 0) {
/* Block until we see a packet. */
goto again;
}
return pkts;
}
#endif /* HAVE_TPACKET3 */
/*
* Attach the given BPF code to the packet capture device.
*/
static int
pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
{
struct pcap_linux *handlep;
struct sock_fprog fcode;
int can_filter_in_kernel;
int err = 0;
int n, offset;
if (!handle)
return -1;
if (!filter) {
pcapint_strlcpy(handle->errbuf, "setfilter: No filter specified",
PCAP_ERRBUF_SIZE);
return -1;
}
handlep = handle->priv;
/* Make our private copy of the filter */
if (pcapint_install_bpf_program(handle, filter) < 0)
/* pcapint_install_bpf_program() filled in errbuf */
return -1;
/*
* Run user level packet filter by default. Will be overridden if
* installing a kernel filter succeeds.
*/
handlep->filter_in_userland = 1;
/* Install kernel level filter if possible */
#ifdef USHRT_MAX
if (handle->fcode.bf_len > USHRT_MAX) {
/*
* fcode.len is an unsigned short for current kernel.
* I have yet to see BPF-Code with that much
* instructions but still it is possible. So for the
* sake of correctness I added this check.
*/
fprintf(stderr, "Warning: Filter too complex for kernel\n");
fcode.len = 0;
fcode.filter = NULL;
can_filter_in_kernel = 0;
} else
#endif /* USHRT_MAX */
{
/*
* Oh joy, the Linux kernel uses struct sock_fprog instead
* of struct bpf_program and of course the length field is
* of different size. Pointed out by Sebastian
*
* Oh, and we also need to fix it up so that all "ret"
* instructions with non-zero operands have MAXIMUM_SNAPLEN
* as the operand if we're not capturing in memory-mapped
* mode, and so that, if we're in cooked mode, all memory-
* reference instructions use special magic offsets in
* references to the link-layer header and assume that the
* link-layer payload begins at 0; "fix_program()" will do
* that.
*/
switch (fix_program(handle, &fcode)) {
case -1:
default:
/*
* Fatal error; just quit.
* (The "default" case shouldn't happen; we
* return -1 for that reason.)
*/
return -1;
case 0:
/*
* The program performed checks that we can't make
* work in the kernel.
*/
can_filter_in_kernel = 0;
break;
case 1:
/*
* We have a filter that'll work in the kernel.
*/
can_filter_in_kernel = 1;
break;
}
}
/*
* NOTE: at this point, we've set both the "len" and "filter"
* fields of "fcode". As of the 2.6.32.4 kernel, at least,
* those are the only members of the "sock_fprog" structure,
* so we initialize every member of that structure.
*
* If there is anything in "fcode" that is not initialized,
* it is either a field added in a later kernel, or it's
* padding.
*
* If a new field is added, this code needs to be updated
* to set it correctly.
*
* If there are no other fields, then:
*
* if the Linux kernel looks at the padding, it's
* buggy;
*
* if the Linux kernel doesn't look at the padding,
* then if some tool complains that we're passing
* uninitialized data to the kernel, then the tool
* is buggy and needs to understand that it's just
* padding.
*/
if (can_filter_in_kernel) {
if ((err = set_kernel_filter(handle, &fcode)) == 0)
{
/*
* Installation succeeded - using kernel filter,
* so userland filtering not needed.
*/
handlep->filter_in_userland = 0;
}
else if (err == -1) /* Non-fatal error */
{
/*
* Print a warning if we weren't able to install
* the filter for a reason other than "this kernel
* isn't configured to support socket filters.
*/
if (errno == ENOMEM) {
/*
* Either a kernel memory allocation
* failure occurred, or there's too
* much "other/option memory" allocated
* for this socket. Suggest that they
* increase the "other/option memory"
* limit.
*/
fprintf(stderr,
"Warning: Couldn't allocate kernel memory for filter: try increasing net.core.optmem_max with sysctl\n");
} else if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
fprintf(stderr,
"Warning: Kernel filter failed: %s\n",
pcap_strerror(errno));
}
}
}
/*
* If we're not using the kernel filter, get rid of any kernel
* filter that might've been there before, e.g. because the
* previous filter could work in the kernel, or because some other
* code attached a filter to the socket by some means other than
* calling "pcap_setfilter()". Otherwise, the kernel filter may
* filter out packets that would pass the new userland filter.
*/
if (handlep->filter_in_userland) {
if (reset_kernel_filter(handle) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't remove kernel filter");
err = -2; /* fatal error */
}
}
/*
* Free up the copy of the filter that was made by "fix_program()".
*/
if (fcode.filter != NULL)
free(fcode.filter);
if (err == -2)
/* Fatal error */
return -1;
/*
* If we're filtering in userland, there's nothing to do;
* the new filter will be used for the next packet.
*/
if (handlep->filter_in_userland)
return 0;
/*
* We're filtering in the kernel; the packets present in
* all blocks currently in the ring were already filtered
* by the old filter, and so will need to be filtered in
* userland by the new filter.
*
* Get an upper bound for the number of such blocks; first,
* walk the ring backward and count the free blocks.
*/
offset = handle->offset;
if (--offset < 0)
offset = handle->cc - 1;
for (n=0; n < handle->cc; ++n) {
if (--offset < 0)
offset = handle->cc - 1;
if (pcap_get_ring_frame_status(handle, offset) != TP_STATUS_KERNEL)
break;
}
/*
* If we found free blocks, decrement the count of free
* blocks by 1, just in case we lost a race with another
* thread of control that was adding a packet while
* we were counting and that had run the filter before
* we changed it.
*
* XXX - could there be more than one block added in
* this fashion?
*
* XXX - is there a way to avoid that race, e.g. somehow
* wait for all packets that passed the old filter to
* be added to the ring?
*/
if (n != 0)
n--;
/*
* Set the count of blocks worth of packets to filter
* in userland to the total number of blocks in the
* ring minus the number of free blocks we found, and
* turn on userland filtering. (The count of blocks
* worth of packets to filter in userland is guaranteed
* not to be zero - n, above, couldn't be set to a
* value > handle->cc, and if it were equal to
* handle->cc, it wouldn't be zero, and thus would
* be decremented to handle->cc - 1.)
*/
handlep->blocks_to_filter_in_userland = handle->cc - n;
handlep->filter_in_userland = 1;
return 0;
}
/*
* Return the index of the given device name. Fill ebuf and return
* -1 on failure.
*/
static int
iface_get_id(int fd, const char *device, char *ebuf)
{
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "SIOCGIFINDEX");
return -1;
}
return ifr.ifr_ifindex;
}
/*
* Bind the socket associated with FD to the given device.
* Return 0 on success or a PCAP_ERROR_ value on a hard error.
*/
static int
iface_bind(int fd, int ifindex, char *ebuf, int protocol)
{
struct sockaddr_ll sll;
int ret, err;
socklen_t errlen = sizeof(err);
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
sll.sll_ifindex = ifindex < 0 ? 0 : ifindex;
sll.sll_protocol = protocol;
if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
if (errno == ENETDOWN) {
/*
* Return a "network down" indication, so that
* the application can report that rather than
* saying we had a mysterious failure and
* suggest that they report a problem to the
* libpcap developers.
*/
return PCAP_ERROR_IFACE_NOT_UP;
}
if (errno == ENODEV) {
/*
* There's nothing more to say, so clear the
* error message.
*/
ebuf[0] = '\0';
ret = PCAP_ERROR_NO_SUCH_DEVICE;
} else {
ret = PCAP_ERROR;
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "bind");
}
return ret;
}
/* Any pending errors, e.g., network is down? */
if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "getsockopt (SO_ERROR)");
return PCAP_ERROR;
}
if (err == ENETDOWN) {
/*
* Return a "network down" indication, so that
* the application can report that rather than
* saying we had a mysterious failure and
* suggest that they report a problem to the
* libpcap developers.
*/
return PCAP_ERROR_IFACE_NOT_UP;
} else if (err > 0) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
err, "bind");
return PCAP_ERROR;
}
return 0;
}
/*
* Try to enter monitor mode.
* If we have libnl, try to create a new monitor-mode device and
* capture on that; otherwise, just say "not supported".
*/
#ifdef HAVE_LIBNL
static int
enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device)
{
struct pcap_linux *handlep = handle->priv;
int ret;
char phydev_path[PATH_MAX+1];
struct nl80211_state nlstate;
struct ifreq ifr;
u_int n;
/*
* Is this a mac80211 device?
*/
ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX);
if (ret < 0)
return ret; /* error */
if (ret == 0)
return 0; /* no error, but not mac80211 device */
/*
* XXX - is this already a monN device?
* If so, we're done.
*/
/*
* OK, it's apparently a mac80211 device.
* Try to find an unused monN device for it.
*/
ret = nl80211_init(handle, &nlstate, device);
if (ret != 0)
return ret;
for (n = 0; n < UINT_MAX; n++) {
/*
* Try mon{n}.
*/
char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */
snprintf(mondevice, sizeof mondevice, "mon%u", n);
ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice);
if (ret == 1) {
/*
* Success. We don't clean up the libnl state
* yet, as we'll be using it later.
*/
goto added;
}
if (ret < 0) {
/*
* Hard failure. Just return ret; handle->errbuf
* has already been set.
*/
nl80211_cleanup(&nlstate);
return ret;
}
}
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"%s: No free monN interfaces", device);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
added:
#if 0
/*
* Sleep for .1 seconds.
*/
delay.tv_sec = 0;
delay.tv_nsec = 500000000;
nanosleep(&delay, NULL);
#endif
/*
* If we haven't already done so, arrange to have
* "pcap_close_all()" called when we exit.
*/
if (!pcapint_do_addexit(handle)) {
/*
* "atexit()" failed; don't put the interface
* in rfmon mode, just give up.
*/
del_mon_if(handle, sock_fd, &nlstate, device,
handlep->mondevice);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
}
/*
* Now configure the monitor interface up.
*/
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, handlep->mondevice, sizeof(ifr.ifr_name));
if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s: Can't get flags for %s", device,
handlep->mondevice);
del_mon_if(handle, sock_fd, &nlstate, device,
handlep->mondevice);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
}
ifr.ifr_flags |= IFF_UP|IFF_RUNNING;
if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s: Can't set flags for %s", device,
handlep->mondevice);
del_mon_if(handle, sock_fd, &nlstate, device,
handlep->mondevice);
nl80211_cleanup(&nlstate);
return PCAP_ERROR;
}
/*
* Success. Clean up the libnl state.
*/
nl80211_cleanup(&nlstate);
/*
* Note that we have to delete the monitor device when we close
* the handle.
*/
handlep->must_do_on_close |= MUST_DELETE_MONIF;
/*
* Add this to the list of pcaps to close when we exit.
*/
pcapint_add_to_pcaps_to_close(handle);
return 1;
}
#else /* HAVE_LIBNL */
static int
enter_rfmon_mode(pcap_t *handle _U_, int sock_fd _U_, const char *device _U_)
{
/*
* We don't have libnl, so we can't do monitor mode.
*/
return 0;
}
#endif /* HAVE_LIBNL */
#if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
/*
* Map SOF_TIMESTAMPING_ values to PCAP_TSTAMP_ values.
*/
static const struct {
int soft_timestamping_val;
int pcap_tstamp_val;
} sof_ts_type_map[3] = {
{ SOF_TIMESTAMPING_SOFTWARE, PCAP_TSTAMP_HOST },
{ SOF_TIMESTAMPING_SYS_HARDWARE, PCAP_TSTAMP_ADAPTER },
{ SOF_TIMESTAMPING_RAW_HARDWARE, PCAP_TSTAMP_ADAPTER_UNSYNCED }
};
#define NUM_SOF_TIMESTAMPING_TYPES (sizeof sof_ts_type_map / sizeof sof_ts_type_map[0])
/*
* Set the list of time stamping types to include all types.
*/
static int
iface_set_all_ts_types(pcap_t *handle, char *ebuf)
{
u_int i;
handle->tstamp_type_list = malloc(NUM_SOF_TIMESTAMPING_TYPES * sizeof(u_int));
if (handle->tstamp_type_list == NULL) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
return -1;
}
for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++)
handle->tstamp_type_list[i] = sof_ts_type_map[i].pcap_tstamp_val;
handle->tstamp_type_count = NUM_SOF_TIMESTAMPING_TYPES;
return 0;
}
/*
* Get a list of time stamp types.
*/
#ifdef ETHTOOL_GET_TS_INFO
static int
iface_get_ts_types(const char *device, pcap_t *handle, char *ebuf)
{
int fd;
struct ifreq ifr;
struct ethtool_ts_info info;
int num_ts_types;
u_int i, j;
/*
* This doesn't apply to the "any" device; you can't say "turn on
* hardware time stamping for all devices that exist now and arrange
* that it be turned on for any device that appears in the future",
* and not all devices even necessarily *support* hardware time
* stamping, so don't report any time stamp types.
*/
if (strcmp(device, "any") == 0) {
handle->tstamp_type_list = NULL;
return 0;
}
/*
* Create a socket from which to fetch time stamping capabilities.
*/
fd = get_if_ioctl_socket();
if (fd < 0) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "socket for SIOCETHTOOL(ETHTOOL_GET_TS_INFO)");
return -1;
}
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
memset(&info, 0, sizeof(info));
info.cmd = ETHTOOL_GET_TS_INFO;
ifr.ifr_data = (caddr_t)&info;
if (ioctl(fd, SIOCETHTOOL, &ifr) == -1) {
int save_errno = errno;
close(fd);
switch (save_errno) {
case EOPNOTSUPP:
case EINVAL:
/*
* OK, this OS version or driver doesn't support
* asking for the time stamping types, so let's
* just return all the possible types.
*/
if (iface_set_all_ts_types(handle, ebuf) == -1)
return -1;
return 0;
case ENODEV:
/*
* OK, no such device.
* The user will find that out when they try to
* activate the device; just return an empty
* list of time stamp types.
*/
handle->tstamp_type_list = NULL;
return 0;
default:
/*
* Other error.
*/
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
save_errno,
"%s: SIOCETHTOOL(ETHTOOL_GET_TS_INFO) ioctl failed",
device);
return -1;
}
}
close(fd);
/*
* Do we support hardware time stamping of *all* packets?
*/
if (!(info.rx_filters & (1 << HWTSTAMP_FILTER_ALL))) {
/*
* No, so don't report any time stamp types.
*
* XXX - some devices either don't report
* HWTSTAMP_FILTER_ALL when they do support it, or
* report HWTSTAMP_FILTER_ALL but map it to only
* time stamping a few PTP packets. See
*
http://marc.info/?l=linux-netdev&m=146318183529571&w=2
*
* Maybe that got fixed later.
*/
handle->tstamp_type_list = NULL;
return 0;
}
num_ts_types = 0;
for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) {
if (info.so_timestamping & sof_ts_type_map[i].soft_timestamping_val)
num_ts_types++;
}
if (num_ts_types != 0) {
handle->tstamp_type_list = malloc(num_ts_types * sizeof(u_int));
if (handle->tstamp_type_list == NULL) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
return -1;
}
for (i = 0, j = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) {
if (info.so_timestamping & sof_ts_type_map[i].soft_timestamping_val) {
handle->tstamp_type_list[j] = sof_ts_type_map[i].pcap_tstamp_val;
j++;
}
}
handle->tstamp_type_count = num_ts_types;
} else
handle->tstamp_type_list = NULL;
return 0;
}
#else /* ETHTOOL_GET_TS_INFO */
static int
iface_get_ts_types(const char *device, pcap_t *handle, char *ebuf)
{
/*
* This doesn't apply to the "any" device; you can't say "turn on
* hardware time stamping for all devices that exist now and arrange
* that it be turned on for any device that appears in the future",
* and not all devices even necessarily *support* hardware time
* stamping, so don't report any time stamp types.
*/
if (strcmp(device, "any") == 0) {
handle->tstamp_type_list = NULL;
return 0;
}
/*
* We don't have an ioctl to use to ask what's supported,
* so say we support everything.
*/
if (iface_set_all_ts_types(handle, ebuf) == -1)
return -1;
return 0;
}
#endif /* ETHTOOL_GET_TS_INFO */
#else /* defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) */
static int
iface_get_ts_types(const char *device _U_, pcap_t *p _U_, char *ebuf _U_)
{
/*
* Nothing to fetch, so it always "succeeds".
*/
return 0;
}
#endif /* defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) */
/*
* Find out if we have any form of fragmentation/reassembly offloading.
*
* We do so using SIOCETHTOOL checking for various types of offloading;
* if SIOCETHTOOL isn't defined, or we don't have any #defines for any
* of the types of offloading, there's nothing we can do to check, so
* we just say "no, we don't".
*
* We treat EOPNOTSUPP, EINVAL and, if eperm_ok is true, EPERM as
* indications that the operation isn't supported. We do EPERM
* weirdly because the SIOCETHTOOL code in later kernels 1) doesn't
* support ETHTOOL_GUFO, 2) also doesn't include it in the list
* of ethtool operations that don't require CAP_NET_ADMIN privileges,
* and 3) does the "is this permitted" check before doing the "is
* this even supported" check, so it fails with "this is not permitted"
* rather than "this is not even supported". To work around this
* annoyance, we only treat EPERM as an error for the first feature,
* and assume that they all do the same permission checks, so if the
* first one is allowed all the others are allowed if supported.
*/
#if defined(SIOCETHTOOL) && (defined(ETHTOOL_GTSO) || defined(ETHTOOL_GUFO) || defined(ETHTOOL_GGSO) || defined(ETHTOOL_GFLAGS) || defined(ETHTOOL_GGRO))
static int
iface_ethtool_flag_ioctl(pcap_t *handle, int cmd, const char *cmdname,
int eperm_ok)
{
struct ifreq ifr;
struct ethtool_value eval;
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, handle->opt.device, sizeof(ifr.ifr_name));
eval.cmd = cmd;
eval.data = 0;
ifr.ifr_data = (caddr_t)&eval;
if (ioctl(handle->fd, SIOCETHTOOL, &ifr) == -1) {
if (errno == EOPNOTSUPP || errno == EINVAL ||
(errno == EPERM && eperm_ok)) {
/*
* OK, let's just return 0, which, in our
* case, either means "no, what we're asking
* about is not enabled" or "all the flags
* are clear (i.e., nothing is enabled)".
*/
return 0;
}
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s: SIOCETHTOOL(%s) ioctl failed",
handle->opt.device, cmdname);
return -1;
}
return eval.data;
}
/*
* XXX - it's annoying that we have to check for offloading at all, but,
* given that we have to, it's still annoying that we have to check for
* particular types of offloading, especially that shiny new types of
* offloading may be added - and, worse, may not be checkable with
* a particular ETHTOOL_ operation; ETHTOOL_GFEATURES would, in
* theory, give those to you, but the actual flags being used are
* opaque (defined in a non-uapi header), and there doesn't seem to
* be any obvious way to ask the kernel what all the offloading flags
* are - at best, you can ask for a set of strings(!) to get *names*
* for various flags. (That whole mechanism appears to have been
* designed for the sole purpose of letting ethtool report flags
* by name and set flags by name, with the names having no semantics
* ethtool understands.)
*/
static int
iface_get_offload(pcap_t *handle)
{
int ret;
#ifdef ETHTOOL_GTSO
ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO", 0);
if (ret == -1)
return -1;
if (ret)
return 1; /* TCP segmentation offloading on */
#endif
#ifdef ETHTOOL_GGSO
/*
* XXX - will this cause large unsegmented packets to be
* handed to PF_PACKET sockets on transmission? If not,
* this need not be checked.
*/
ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GGSO, "ETHTOOL_GGSO", 0);
if (ret == -1)
return -1;
if (ret)
return 1; /* generic segmentation offloading on */
#endif
#ifdef ETHTOOL_GFLAGS
ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS", 0);
if (ret == -1)
return -1;
if (ret & ETH_FLAG_LRO)
return 1; /* large receive offloading on */
#endif
#ifdef ETHTOOL_GGRO
/*
* XXX - will this cause large reassembled packets to be
* handed to PF_PACKET sockets on receipt? If not,
* this need not be checked.
*/
ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GGRO, "ETHTOOL_GGRO", 0);
if (ret == -1)
return -1;
if (ret)
return 1; /* generic (large) receive offloading on */
#endif
#ifdef ETHTOOL_GUFO
/*
* Do this one last, as support for it was removed in later
* kernels, and it fails with EPERM on those kernels rather
* than with EOPNOTSUPP (see explanation in comment for
* iface_ethtool_flag_ioctl()).
*/
ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO", 1);
if (ret == -1)
return -1;
if (ret)
return 1; /* UDP fragmentation offloading on */
#endif
return 0;
}
#else /* SIOCETHTOOL */
static int
iface_get_offload(pcap_t *handle _U_)
{
/*
* XXX - do we need to get this information if we don't
* have the ethtool ioctls? If so, how do we do that?
*/
return 0;
}
#endif /* SIOCETHTOOL */
static struct dsa_proto {
const char *name;
bpf_u_int32 linktype;
} dsa_protos[] = {
/*
* None is special and indicates that the interface does not have
* any tagging protocol configured, and is therefore a standard
* Ethernet interface.
*/
{ "none", DLT_EN10MB },
{ "brcm", DLT_DSA_TAG_BRCM },
{ "brcm-prepend", DLT_DSA_TAG_BRCM_PREPEND },
{ "dsa", DLT_DSA_TAG_DSA },
{ "edsa", DLT_DSA_TAG_EDSA },
};
static int
iface_dsa_get_proto_info(const char *device, pcap_t *handle)
{
char *pathstr;
unsigned int i;
/*
* Make this significantly smaller than PCAP_ERRBUF_SIZE;
* the tag *shouldn't* have some huge long name, and making
* it smaller keeps newer versions of GCC from whining that
* the error message if we don't support the tag could
* overflow the error message buffer.
*/
char buf[128];
ssize_t r;
int fd;
fd = asprintf(&pathstr, "/sys/class/net/%s/dsa/tagging", device);
if (fd < 0) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
fd, "asprintf");
return PCAP_ERROR;
}
fd = open(pathstr, O_RDONLY);
free(pathstr);
/*
* This is not fatal, kernel >= 4.20 *might* expose this attribute
*/
if (fd < 0)
return 0;
r = read(fd, buf, sizeof(buf) - 1);
if (r <= 0) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "read");
close(fd);
return PCAP_ERROR;
}
close(fd);
/*
* Buffer should be LF terminated.
*/
if (buf[r - 1] == '\n')
r--;
buf[r] = '\0';
for (i = 0; i < sizeof(dsa_protos) / sizeof(dsa_protos[0]); i++) {
if (strlen(dsa_protos[i].name) == (size_t)r &&
strcmp(buf, dsa_protos[i].name) == 0) {
handle->linktype = dsa_protos[i].linktype;
switch (dsa_protos[i].linktype) {
case DLT_EN10MB:
return 0;
default:
return 1;
}
}
}
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"unsupported DSA tag: %s", buf);
return PCAP_ERROR;
}
/*
* Query the kernel for the MTU of the given interface.
*/
static int
iface_get_mtu(int fd, const char *device, char *ebuf)
{
struct ifreq ifr;
if (!device)
return BIGGER_THAN_ALL_MTUS;
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "SIOCGIFMTU");
return -1;
}
return ifr.ifr_mtu;
}
/*
* Get the hardware type of the given interface as ARPHRD_xxx constant.
*/
static int
iface_get_arptype(int fd, const char *device, char *ebuf)
{
struct ifreq ifr;
int ret;
memset(&ifr, 0, sizeof(ifr));
pcapint_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
if (errno == ENODEV) {
/*
* No such device.
*
* There's nothing more to say, so clear
* the error message.
*/
ret = PCAP_ERROR_NO_SUCH_DEVICE;
ebuf[0] = '\0';
} else {
ret = PCAP_ERROR;
pcapint_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE,
errno, "SIOCGIFHWADDR");
}
return ret;
}
return ifr.ifr_hwaddr.sa_family;
}
static int
fix_program(pcap_t *handle, struct sock_fprog *fcode)
{
struct pcap_linux *handlep = handle->priv;
size_t prog_size;
register int i;
register struct bpf_insn *p;
struct bpf_insn *f;
int len;
/*
* Make a copy of the filter, and modify that copy if
* necessary.
*/
prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
len = handle->fcode.bf_len;
f = (struct bpf_insn *)malloc(prog_size);
if (f == NULL) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
return -1;
}
memcpy(f, handle->fcode.bf_insns, prog_size);
fcode->len = len;
fcode->filter = (struct sock_filter *) f;
for (i = 0; i < len; ++i) {
p = &f[i];
/*
* What type of instruction is this?
*/
switch (BPF_CLASS(p->code)) {
case BPF_LD:
case BPF_LDX:
/*
* It's a load instruction; is it loading
* from the packet?
*/
switch (BPF_MODE(p->code)) {
case BPF_ABS:
case BPF_IND:
case BPF_MSH:
/*
* Yes; are we in cooked mode?
*/
if (handlep->cooked) {
/*
* Yes, so we need to fix this
* instruction.
*/
if (fix_offset(handle, p) < 0) {
/*
* We failed to do so.
* Return 0, so our caller
* knows to punt to userland.
*/
return 0;
}
}
break;
}
break;
}
}
return 1; /* we succeeded */
}
static int
fix_offset(pcap_t *handle, struct bpf_insn *p)
{
/*
* Existing references to auxiliary data shouldn't be adjusted.
*
* Note that SKF_AD_OFF is negative, but p->k is unsigned, so
* we use >= and cast SKF_AD_OFF to unsigned.
*/
if (p->k >= (bpf_u_int32)SKF_AD_OFF)
return 0;
if (handle->linktype == DLT_LINUX_SLL2) {
/*
* What's the offset?
*/
if (p->k >= SLL2_HDR_LEN) {
/*
* It's within the link-layer payload; that starts
* at an offset of 0, as far as the kernel packet
* filter is concerned, so subtract the length of
* the link-layer header.
*/
p->k -= SLL2_HDR_LEN;
} else if (p->k == 0) {
/*
* It's the protocol field; map it to the
* special magic kernel offset for that field.
*/
p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
} else if (p->k == 4) {
/*
* It's the ifindex field; map it to the
* special magic kernel offset for that field.
*/
p->k = SKF_AD_OFF + SKF_AD_IFINDEX;
} else if (p->k == 10) {
/*
* It's the packet type field; map it to the
* special magic kernel offset for that field.
*/
p->k = SKF_AD_OFF + SKF_AD_PKTTYPE;
} else if ((bpf_int32)(p->k) > 0) {
/*
* It's within the header, but it's not one of
* those fields; we can't do that in the kernel,
* so punt to userland.
*/
return -1;
}
} else {
/*
* What's the offset?
*/
if (p->k >= SLL_HDR_LEN) {
/*
* It's within the link-layer payload; that starts
* at an offset of 0, as far as the kernel packet
* filter is concerned, so subtract the length of
* the link-layer header.
*/
p->k -= SLL_HDR_LEN;
} else if (p->k == 0) {
/*
* It's the packet type field; map it to the
* special magic kernel offset for that field.
*/
p->k = SKF_AD_OFF + SKF_AD_PKTTYPE;
} else if (p->k == 14) {
/*
* It's the protocol field; map it to the
* special magic kernel offset for that field.
*/
p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
} else if ((bpf_int32)(p->k) > 0) {
/*
* It's within the header, but it's not one of
* those fields; we can't do that in the kernel,
* so punt to userland.
*/
return -1;
}
}
return 0;
}
static int
set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
{
int total_filter_on = 0;
int save_mode;
int ret;
int save_errno;
/*
* The socket filter code doesn't discard all packets queued
* up on the socket when the filter is changed; this means
* that packets that don't match the new filter may show up
* after the new filter is put onto the socket, if those
* packets haven't yet been read.
*
* This means, for example, that if you do a tcpdump capture
* with a filter, the first few packets in the capture might
* be packets that wouldn't have passed the filter.
*
* We therefore discard all packets queued up on the socket
* when setting a kernel filter. (This isn't an issue for
* userland filters, as the userland filtering is done after
* packets are queued up.)
*
* To flush those packets, we put the socket in read-only mode,
* and read packets from the socket until there are no more to
* read.
*
* In order to keep that from being an infinite loop - i.e.,
* to keep more packets from arriving while we're draining
* the queue - we put the "total filter", which is a filter
* that rejects all packets, onto the socket before draining
* the queue.
*
* This code deliberately ignores any errors, so that you may
* get bogus packets if an error occurs, rather than having
* the filtering done in userland even if it could have been
* done in the kernel.
*/
if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
&total_fcode, sizeof(total_fcode)) == 0) {
char drain[1];
/*
* Note that we've put the total filter onto the socket.
*/
total_filter_on = 1;
/*
* Save the socket's current mode, and put it in
* non-blocking mode; we drain it by reading packets
* until we get an error (which is normally a
* "nothing more to be read" error).
*/
save_mode = fcntl(handle->fd, F_GETFL, 0);
if (save_mode == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't get FD flags when changing filter");
return -2;
}
if (fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) < 0) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't set nonblocking mode when changing filter");
return -2;
}
while (recv(handle->fd, &drain, sizeof drain, MSG_TRUNC) >= 0)
;
save_errno = errno;
if (save_errno != EAGAIN) {
/*
* Fatal error.
*
* If we can't restore the mode or reset the
* kernel filter, there's nothing we can do.
*/
(void)fcntl(handle->fd, F_SETFL, save_mode);
(void)reset_kernel_filter(handle);
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, save_errno,
"recv failed when changing filter");
return -2;
}
if (fcntl(handle->fd, F_SETFL, save_mode) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't restore FD flags when changing filter");
return -2;
}
}
/*
* Now attach the new filter.
*/
ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
fcode, sizeof(*fcode));
if (ret == -1 && total_filter_on) {
/*
* Well, we couldn't set that filter on the socket,
* but we could set the total filter on the socket.
*
* This could, for example, mean that the filter was
* too big to put into the kernel, so we'll have to
* filter in userland; in any case, we'll be doing
* filtering in userland, so we need to remove the
* total filter so we see packets.
*/
save_errno = errno;
/*
* If this fails, we're really screwed; we have the
* total filter on the socket, and it won't come off.
* Report it as a fatal error.
*/
if (reset_kernel_filter(handle) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"can't remove kernel total filter");
return -2; /* fatal error */
}
errno = save_errno;
}
return ret;
}
static int
reset_kernel_filter(pcap_t *handle)
{
int ret;
/*
* setsockopt() barfs unless it get a dummy parameter.
* valgrind whines unless the value is initialized,
* as it has no idea that setsockopt() ignores its
* parameter.
*/
int dummy = 0;
ret = setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
&dummy, sizeof(dummy));
/*
* Ignore ENOENT - it means "we don't have a filter", so there
* was no filter to remove, and there's still no filter.
*
* Also ignore ENONET, as a lot of kernel versions had a
* typo where ENONET, rather than ENOENT, was returned.
*/
if (ret == -1 && errno != ENOENT && errno != ENONET)
return -1;
return 0;
}
int
pcap_set_protocol_linux(pcap_t *p, int protocol)
{
if (pcapint_check_activated(p))
return (PCAP_ERROR_ACTIVATED);
p->opt.protocol = protocol;
return (0);
}
/*
* Libpcap version string.
*/
const char *
pcap_lib_version(void)
{
#if defined(HAVE_TPACKET3)
return (PCAP_VERSION_STRING " (with TPACKET_V3)");
#else
return (PCAP_VERSION_STRING " (with TPACKET_V2)");
#endif
}
