/* $NetBSD: pcap-usb-linux.c,v 1.8 2024/09/02 15:33:37 christos Exp $ */
/*
* Copyright (c) 2006 Paolo Abeni (Italy)
* 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 COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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 COPYRIGHT
* OWNER OR CONTRIBUTORS 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.
*
* USB sniffing API implementation for Linux platform
* By Paolo Abeni <
[email protected]>
* Modifications: Kris Katterjohn <
[email protected]>
*
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: pcap-usb-linux.c,v 1.8 2024/09/02 15:33:37 christos Exp $");
#include <config.h>
#include "pcap/usb.h"
#include "pcap-int.h"
#include "pcap-usb-linux.h"
#include "pcap-usb-linux-common.h"
#include "extract.h"
#ifdef NEED_STRERROR_H
#include "strerror.h"
#endif
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <limits.h>
#include <string.h>
#include <dirent.h>
#ifdef __linux__
#include <byteswap.h>
#endif
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#ifdef HAVE_LINUX_USBDEVICE_FS_H
/*
* We might need <linux/compiler.h> to define __user for
* <linux/usbdevice_fs.h>.
*/
#ifdef HAVE_LINUX_COMPILER_H
#include <linux/compiler.h>
#endif /* HAVE_LINUX_COMPILER_H */
#include <linux/usbdevice_fs.h>
#endif /* HAVE_LINUX_USBDEVICE_FS_H */
#include "diag-control.h"
#define USB_IFACE "usbmon"
#define USBMON_DEV_PREFIX "usbmon"
#define USBMON_DEV_PREFIX_LEN (sizeof USBMON_DEV_PREFIX - 1)
#define USB_LINE_LEN 4096
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define htols(s) s
#define htoll(l) l
#define htol64(ll) ll
#else
#define htols(s) bswap_16(s)
#define htoll(l) bswap_32(l)
#define htol64(ll) bswap_64(ll)
#endif
struct mon_bin_stats {
uint32_t queued;
uint32_t dropped;
};
struct mon_bin_get {
pcap_usb_header *hdr;
void *data;
size_t data_len; /* Length of data (can be zero) */
};
struct mon_bin_mfetch {
int32_t *offvec; /* Vector of events fetched */
int32_t nfetch; /* Number of events to fetch (out: fetched) */
int32_t nflush; /* Number of events to flush */
};
#define MON_IOC_MAGIC 0x92
#define MON_IOCQ_URB_LEN _IO(MON_IOC_MAGIC, 1)
#define MON_IOCX_URB _IOWR(MON_IOC_MAGIC, 2, struct mon_bin_hdr)
#define MON_IOCG_STATS _IOR(MON_IOC_MAGIC, 3, struct mon_bin_stats)
#define MON_IOCT_RING_SIZE _IO(MON_IOC_MAGIC, 4)
#define MON_IOCQ_RING_SIZE _IO(MON_IOC_MAGIC, 5)
#define MON_IOCX_GET _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get)
#define MON_IOCX_MFETCH _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch)
#define MON_IOCH_MFLUSH _IO(MON_IOC_MAGIC, 8)
#define MON_BIN_SETUP 0x1 /* setup hdr is present*/
#define MON_BIN_SETUP_ZERO 0x2 /* setup buffer is not available */
#define MON_BIN_DATA_ZERO 0x4 /* data buffer is not available */
#define MON_BIN_ERROR 0x8
/*
* Private data for capturing on Linux USB.
*/
struct pcap_usb_linux {
u_char *mmapbuf; /* memory-mapped region pointer */
size_t mmapbuflen; /* size of region */
int bus_index;
u_int packets_read;
};
/* forward declaration */
static int usb_activate(pcap_t *);
static int usb_stats_linux_bin(pcap_t *, struct pcap_stat *);
static int usb_read_linux_bin(pcap_t *, int , pcap_handler , u_char *);
static int usb_read_linux_mmap(pcap_t *, int , pcap_handler , u_char *);
static int usb_inject_linux(pcap_t *, const void *, size_t);
static int usb_setdirection_linux(pcap_t *, pcap_direction_t);
static void usb_cleanup_linux_mmap(pcap_t *);
/* facility to add an USB device to the device list*/
static int
usb_dev_add(pcap_if_list_t *devlistp, int n, char *err_str)
{
char dev_name[10];
char dev_descr[30];
snprintf(dev_name, 10, USB_IFACE"%d", n);
/*
* XXX - is there any notion of "up" and "running"?
*/
if (n == 0) {
/*
* As this refers to all buses, there's no notion of
* "connected" vs. "disconnected", as that's a property
* that would apply to a particular USB interface.
*/
if (pcapint_add_dev(devlistp, dev_name,
PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
"Raw USB traffic, all USB buses", err_str) == NULL)
return -1;
} else {
/*
* XXX - is there a way to determine whether anything's
* plugged into this bus interface or not, and set
* PCAP_IF_CONNECTION_STATUS_CONNECTED or
* PCAP_IF_CONNECTION_STATUS_DISCONNECTED?
*/
snprintf(dev_descr, 30, "Raw USB traffic, bus number %d", n);
if (pcapint_add_dev(devlistp, dev_name, 0, dev_descr, err_str) == NULL)
return -1;
}
return 0;
}
int
usb_findalldevs(pcap_if_list_t *devlistp, char *err_str)
{
struct dirent* data;
int ret = 0;
DIR* dir;
int n;
char* name;
/*
* We require 2.6.27 or later kernels, so we have binary-mode support.
* The devices are of the form /dev/usbmon{N}.
* Open /dev and scan it.
*/
dir = opendir("/dev");
if (dir != NULL) {
while ((ret == 0) && ((data = readdir(dir)) != 0)) {
name = data->d_name;
/*
* Is this a usbmon device?
*/
if (strncmp(name, USBMON_DEV_PREFIX,
USBMON_DEV_PREFIX_LEN) != 0)
continue; /* no */
/*
* What's the device number?
*/
if (sscanf(&name[USBMON_DEV_PREFIX_LEN], "%d", &n) == 0)
continue; /* failed */
ret = usb_dev_add(devlistp, n, err_str);
}
closedir(dir);
}
return 0;
}
/*
* Matches what's in mon_bin.c in the Linux kernel.
*/
#define MIN_RING_SIZE (8*1024)
#define MAX_RING_SIZE (1200*1024)
static int
usb_set_ring_size(pcap_t* handle, int header_size)
{
/*
* A packet from binary usbmon has:
*
* 1) a fixed-length header, of size header_size;
* 2) descriptors, for isochronous transfers;
* 3) the payload.
*
* The kernel buffer has a size, defaulting to 300KB, with a
* minimum of 8KB and a maximum of 1200KB. The size is set with
* the MON_IOCT_RING_SIZE ioctl; the size passed in is rounded up
* to a page size.
*
* No more than {buffer size}/5 bytes worth of payload is saved.
* Therefore, if we subtract the fixed-length size from the
* snapshot length, we have the biggest payload we want (we
* don't worry about the descriptors - if we have descriptors,
* we'll just discard the last bit of the payload to get it
* to fit). We multiply that result by 5 and set the buffer
* size to that value.
*/
int ring_size;
if (handle->snapshot < header_size)
handle->snapshot = header_size;
/* The maximum snapshot size is small enough that this won't overflow */
ring_size = (handle->snapshot - header_size) * 5;
/*
* Will this get an error?
* (There's no way to query the minimum or maximum, so we just
* copy the value from the kernel source. We don't round it
* up to a multiple of the page size.)
*/
if (ring_size > MAX_RING_SIZE) {
/*
* Yes. Lower the ring size to the maximum, and set the
* snapshot length to the value that would give us a
* maximum-size ring.
*/
ring_size = MAX_RING_SIZE;
handle->snapshot = header_size + (MAX_RING_SIZE/5);
} else if (ring_size < MIN_RING_SIZE) {
/*
* Yes. Raise the ring size to the minimum, but leave
* the snapshot length unchanged, so we show the
* callback no more data than specified by the
* snapshot length.
*/
ring_size = MIN_RING_SIZE;
}
if (ioctl(handle->fd, MON_IOCT_RING_SIZE, ring_size) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't set ring size from fd %d", handle->fd);
return -1;
}
return ring_size;
}
static
int usb_mmap(pcap_t* handle)
{
struct pcap_usb_linux *handlep = handle->priv;
int len;
/*
* Attempt to set the ring size as appropriate for the snapshot
* length, reducing the snapshot length if that'd make the ring
* bigger than the kernel supports.
*/
len = usb_set_ring_size(handle, (int)sizeof(pcap_usb_header_mmapped));
if (len == -1) {
/* Failed. Fall back on non-memory-mapped access. */
return 0;
}
handlep->mmapbuflen = len;
handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ,
MAP_SHARED, handle->fd, 0);
if (handlep->mmapbuf == MAP_FAILED) {
/*
* Failed. We don't treat that as a fatal error, we
* just try to fall back on non-memory-mapped access.
*/
return 0;
}
return 1;
}
#ifdef HAVE_LINUX_USBDEVICE_FS_H
#define CTRL_TIMEOUT (5*1000) /* milliseconds */
#define USB_DIR_IN 0x80
#define USB_TYPE_STANDARD 0x00
#define USB_RECIP_DEVICE 0x00
#define USB_REQ_GET_DESCRIPTOR 6
#define USB_DT_DEVICE 1
#define USB_DT_CONFIG 2
#define USB_DEVICE_DESCRIPTOR_SIZE 18
#define USB_CONFIG_DESCRIPTOR_SIZE 9
/* probe the descriptors of the devices attached to the bus */
/* the descriptors will end up in the captured packet stream */
/* and be decoded by external apps like wireshark */
/* without these identifying probes packet data can't be fully decoded */
static void
probe_devices(int bus)
{
struct usbdevfs_ctrltransfer ctrl;
struct dirent* data;
int ret = 0;
char busdevpath[sizeof("/dev/bus/usb/000/") + NAME_MAX];
DIR* dir;
uint8_t descriptor[USB_DEVICE_DESCRIPTOR_SIZE];
uint8_t configdesc[USB_CONFIG_DESCRIPTOR_SIZE];
/* scan usb bus directories for device nodes */
snprintf(busdevpath, sizeof(busdevpath), "/dev/bus/usb/%03d", bus);
dir = opendir(busdevpath);
if (!dir)
return;
while ((ret >= 0) && ((data = readdir(dir)) != 0)) {
int fd;
char* name = data->d_name;
if (name[0] == '.')
continue;
snprintf(busdevpath, sizeof(busdevpath), "/dev/bus/usb/%03d/%s", bus, data->d_name);
fd = open(busdevpath, O_RDWR);
if (fd == -1)
continue;
/*
* Sigh. Different kernels have different member names
* for this structure.
*/
#ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE
ctrl.bRequestType = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
ctrl.bRequest = USB_REQ_GET_DESCRIPTOR;
ctrl.wValue = USB_DT_DEVICE << 8;
ctrl.wIndex = 0;
ctrl.wLength = sizeof(descriptor);
#else
ctrl.requesttype = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
ctrl.request = USB_REQ_GET_DESCRIPTOR;
ctrl.value = USB_DT_DEVICE << 8;
ctrl.index = 0;
ctrl.length = sizeof(descriptor);
#endif
ctrl.data = descriptor;
ctrl.timeout = CTRL_TIMEOUT;
ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl);
/* Request CONFIGURATION descriptor alone to know wTotalLength */
#ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE
ctrl.wValue = USB_DT_CONFIG << 8;
ctrl.wLength = sizeof(configdesc);
#else
ctrl.value = USB_DT_CONFIG << 8;
ctrl.length = sizeof(configdesc);
#endif
ctrl.data = configdesc;
ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl);
if (ret >= 0) {
uint16_t wtotallength;
wtotallength = EXTRACT_LE_U_2(&configdesc[2]);
#ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE
ctrl.wLength = wtotallength;
#else
ctrl.length = wtotallength;
#endif
ctrl.data = malloc(wtotallength);
if (ctrl.data) {
ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl);
free(ctrl.data);
}
}
close(fd);
}
closedir(dir);
}
#endif /* HAVE_LINUX_USBDEVICE_FS_H */
pcap_t *
usb_create(const char *device, char *ebuf, int *is_ours)
{
const char *cp;
char *cpend;
long devnum;
pcap_t *p;
/* Does this look like a USB monitoring device? */
cp = strrchr(device, '/');
if (cp == NULL)
cp = device;
/* Does it begin with USB_IFACE? */
if (strncmp(cp, USB_IFACE, sizeof USB_IFACE - 1) != 0) {
/* Nope, doesn't begin with USB_IFACE */
*is_ours = 0;
return NULL;
}
/* Yes - is USB_IFACE followed by a number? */
cp += sizeof USB_IFACE - 1;
devnum = strtol(cp, &cpend, 10);
if (cpend == cp || *cpend != '\0') {
/* Not followed by a number. */
*is_ours = 0;
return NULL;
}
if (devnum < 0) {
/* Followed by a non-valid number. */
*is_ours = 0;
return NULL;
}
/* OK, it's probably ours. */
*is_ours = 1;
p = PCAP_CREATE_COMMON(ebuf, struct pcap_usb_linux);
if (p == NULL)
return (NULL);
p->activate_op = usb_activate;
return (p);
}
static int
usb_activate(pcap_t* handle)
{
struct pcap_usb_linux *handlep = handle->priv;
char full_path[USB_LINE_LEN];
/*
* 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;
/* Initialize some components of the pcap structure. */
handle->bufsize = handle->snapshot;
handle->offset = 0;
handle->linktype = DLT_USB_LINUX;
handle->inject_op = usb_inject_linux;
handle->setfilter_op = pcapint_install_bpf_program; /* no kernel filtering */
handle->setdirection_op = usb_setdirection_linux;
handle->set_datalink_op = NULL; /* can't change data link type */
handle->getnonblock_op = pcapint_getnonblock_fd;
handle->setnonblock_op = pcapint_setnonblock_fd;
/*get usb bus index from device name */
if (sscanf(handle->opt.device, USB_IFACE"%d", &handlep->bus_index) != 1)
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Can't get USB bus index from %s", handle->opt.device);
return PCAP_ERROR;
}
/*
* We require 2.6.27 or later kernels, so we have binary-mode support.
* Try to open the binary interface.
*/
snprintf(full_path, USB_LINE_LEN, "/dev/"USBMON_DEV_PREFIX"%d",
handlep->bus_index);
handle->fd = open(full_path, O_RDONLY, 0);
if (handle->fd < 0)
{
/*
* The attempt failed; why?
*/
switch (errno) {
case ENOENT:
/*
* The device doesn't exist.
* That could either mean that there's
* no support for monitoring USB buses
* (which probably means "the usbmon
* module isn't loaded") or that there
* is but that *particular* device
* doesn't exist (no "scan all buses"
* device if the bus index is 0, no
* such bus if the bus index isn't 0).
*
* For now, don't provide an error message;
* if we can determine what the particular
* problem is, we should report that.
*/
handle->errbuf[0] = '\0';
return PCAP_ERROR_NO_SUCH_DEVICE;
case EACCES:
/*
* We didn't have permission to open it.
*/
DIAG_OFF_FORMAT_TRUNCATION
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Attempt to open %s failed with EACCES - root privileges may be required",
full_path);
DIAG_ON_FORMAT_TRUNCATION
return PCAP_ERROR_PERM_DENIED;
default:
/*
* Something went wrong.
*/
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno,
"Can't open USB bus file %s", full_path);
return PCAP_ERROR;
}
}
if (handle->opt.rfmon)
{
/*
* Monitor mode doesn't apply to USB devices.
*/
close(handle->fd);
return PCAP_ERROR_RFMON_NOTSUP;
}
/* try to use fast mmap access */
if (usb_mmap(handle))
{
/* We succeeded. */
handle->linktype = DLT_USB_LINUX_MMAPPED;
handle->stats_op = usb_stats_linux_bin;
handle->read_op = usb_read_linux_mmap;
handle->cleanup_op = usb_cleanup_linux_mmap;
#ifdef HAVE_LINUX_USBDEVICE_FS_H
probe_devices(handlep->bus_index);
#endif
/*
* "handle->fd" is a real file, so
* "select()" and "poll()" work on it.
*/
handle->selectable_fd = handle->fd;
return 0;
}
/*
* We failed; try plain binary interface access.
*
* Attempt to set the ring size as appropriate for
* the snapshot length, reducing the snapshot length
* if that'd make the ring bigger than the kernel
* supports.
*/
if (usb_set_ring_size(handle, (int)sizeof(pcap_usb_header)) == -1) {
/* Failed. */
close(handle->fd);
return PCAP_ERROR;
}
handle->stats_op = usb_stats_linux_bin;
handle->read_op = usb_read_linux_bin;
#ifdef HAVE_LINUX_USBDEVICE_FS_H
probe_devices(handlep->bus_index);
#endif
/*
* "handle->fd" is a real file, so "select()" and "poll()"
* work on it.
*/
handle->selectable_fd = handle->fd;
/* for plain binary access and text access we need to allocate the read
* buffer */
handle->buffer = malloc(handle->bufsize);
if (!handle->buffer) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
close(handle->fd);
return PCAP_ERROR;
}
return 0;
}
static int
usb_inject_linux(pcap_t *handle, const void *buf _U_, size_t size _U_)
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Packet injection is not supported on USB devices");
return (-1);
}
static int
usb_setdirection_linux(pcap_t *p, pcap_direction_t d)
{
/*
* It's guaranteed, at this point, that d is a valid
* direction value.
*/
p->direction = d;
return 0;
}
static int
usb_stats_linux_bin(pcap_t *handle, struct pcap_stat *stats)
{
struct pcap_usb_linux *handlep = handle->priv;
int ret;
struct mon_bin_stats st;
ret = ioctl(handle->fd, MON_IOCG_STATS, &st);
if (ret < 0)
{
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't read stats from fd %d", handle->fd);
return -1;
}
stats->ps_recv = handlep->packets_read + st.queued;
stats->ps_drop = st.dropped;
stats->ps_ifdrop = 0;
return 0;
}
/*
* see <linux-kernel-source>/Documentation/usb/usbmon.txt and
* <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
*/
static int
usb_read_linux_bin(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
{
struct pcap_usb_linux *handlep = handle->priv;
struct mon_bin_get info;
int ret;
struct pcap_pkthdr pkth;
u_int clen = handle->snapshot - sizeof(pcap_usb_header);
/* the usb header is going to be part of 'packet' data*/
info.hdr = (pcap_usb_header*) handle->buffer;
info.data = (u_char *)handle->buffer + sizeof(pcap_usb_header);
info.data_len = clen;
/* ignore interrupt system call errors */
do {
ret = ioctl(handle->fd, MON_IOCX_GET, &info);
if (handle->break_loop)
{
handle->break_loop = 0;
return -2;
}
} while ((ret == -1) && (errno == EINTR));
if (ret < 0)
{
if (errno == EAGAIN)
return 0; /* no data there */
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't read from fd %d", handle->fd);
return -1;
}
/*
* info.hdr->data_len is the number of bytes of isochronous
* descriptors (if any) plus the number of bytes of data
* provided. There are no isochronous descriptors here,
* because we're using the old 48-byte header.
*
* If info.hdr->data_flag is non-zero, there's no URB data;
* info.hdr->urb_len is the size of the buffer into which
* data is to be placed; it does not represent the amount
* of data transferred. If info.hdr->data_flag is zero,
* there is URB data, and info.hdr->urb_len is the number
* of bytes transmitted or received; it doesn't include
* isochronous descriptors.
*
* The kernel may give us more data than the snaplen; if it did,
* reduce the data length so that the total number of bytes we
* tell our client we have is not greater than the snaplen.
*/
if (info.hdr->data_len < clen)
clen = info.hdr->data_len;
info.hdr->data_len = clen;
pkth.caplen = sizeof(pcap_usb_header) + clen;
if (info.hdr->data_flag) {
/*
* No data; just base the original length on
* info.hdr->data_len (so that it's >= the captured
* length).
*/
pkth.len = sizeof(pcap_usb_header) + info.hdr->data_len;
} else {
/*
* We got data; base the original length on
* info.hdr->urb_len, so that it includes data
* discarded by the USB monitor device due to
* its buffer being too small.
*/
pkth.len = sizeof(pcap_usb_header) + info.hdr->urb_len;
}
pkth.ts.tv_sec = (time_t)info.hdr->ts_sec;
pkth.ts.tv_usec = info.hdr->ts_usec;
if (handle->fcode.bf_insns == NULL ||
pcapint_filter(handle->fcode.bf_insns, handle->buffer,
pkth.len, pkth.caplen)) {
handlep->packets_read++;
callback(user, &pkth, handle->buffer);
return 1;
}
return 0; /* didn't pass filter */
}
/*
* see <linux-kernel-source>/Documentation/usb/usbmon.txt and
* <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
*/
#define VEC_SIZE 32
static int
usb_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
{
struct pcap_usb_linux *handlep = handle->priv;
struct mon_bin_mfetch fetch;
int32_t vec[VEC_SIZE];
struct pcap_pkthdr pkth;
u_char *bp;
pcap_usb_header_mmapped* hdr;
int nflush = 0;
int packets = 0;
u_int clen, max_clen;
max_clen = handle->snapshot - sizeof(pcap_usb_header_mmapped);
for (;;) {
int i, ret;
int limit;
if (PACKET_COUNT_IS_UNLIMITED(max_packets)) {
/*
* There's no limit on the number of packets
* to process, so try to fetch VEC_SIZE packets.
*/
limit = VEC_SIZE;
} else {
/*
* Try to fetch as many packets as we have left
* to process, or VEC_SIZE packets, whichever
* is less.
*
* At this point, max_packets > 0 (otherwise,
* PACKET_COUNT_IS_UNLIMITED(max_packets)
* would be true) and max_packets > packets
* (packet starts out as 0, and the test
* at the bottom of the loop exits if
* max_packets <= packets), so limit is
* guaranteed to be > 0.
*/
limit = max_packets - packets;
if (limit > VEC_SIZE)
limit = VEC_SIZE;
}
/*
* Try to fetch as many events as possible, up to
* the limit, and flush the events we've processed
* earlier (nflush) - MON_IOCX_MFETCH does both
* (presumably to reduce the number of system
* calls in loops like this).
*/
fetch.offvec = vec;
fetch.nfetch = limit;
fetch.nflush = nflush;
/* ignore interrupt system call errors */
do {
ret = ioctl(handle->fd, MON_IOCX_MFETCH, &fetch);
if (handle->break_loop)
{
handle->break_loop = 0;
return -2;
}
} while ((ret == -1) && (errno == EINTR));
if (ret < 0)
{
if (errno == EAGAIN)
return 0; /* no data there */
pcapint_fmt_errmsg_for_errno(handle->errbuf,
PCAP_ERRBUF_SIZE, errno, "Can't mfetch fd %d",
handle->fd);
return -1;
}
/* keep track of processed events, we will flush them later */
nflush = fetch.nfetch;
for (i=0; i<fetch.nfetch; ++i) {
/*
* XXX - we can't check break_loop here, as
* we read the indices of packets into a
* local variable, so if we're later called
* to fetch more packets, those packets will
* not be seen - and won't be flushed, either.
*
* Instead, we would have to keep the array
* of indices in our private data, along
* with the count of packets to flush - or
* would have to flush the already-processed
* packets if we break out of the loop here.
*/
/* Get a pointer to this packet's buffer */
bp = &handlep->mmapbuf[vec[i]];
/* That begins with a metadata header */
hdr = (pcap_usb_header_mmapped*) bp;
/* discard filler */
if (hdr->event_type == '@')
continue;
/*
* hdr->data_len is the number of bytes of
* isochronous descriptors (if any) plus the
* number of bytes of data provided.
*
* If hdr->data_flag is non-zero, there's no
* URB data; hdr->urb_len is the size of the
* buffer into which data is to be placed; it does
* not represent the amount of data transferred.
* If hdr->data_flag is zero, there is URB data,
* and hdr->urb_len is the number of bytes
* transmitted or received; it doesn't include
* isochronous descriptors.
*
* The kernel may give us more data than the
* snaplen; if it did, reduce the data length
* so that the total number of bytes we
* tell our client we have is not greater than
* the snaplen.
*/
clen = max_clen;
if (hdr->data_len < clen)
clen = hdr->data_len;
pkth.caplen = sizeof(pcap_usb_header_mmapped) + clen;
if (hdr->data_flag) {
/*
* No data; just base the original length
* on hdr->data_len (so that it's >= the
* captured length). Clamp the result
* at UINT_MAX, so it fits in an unsigned
* int.
*/
pkth.len = u_int_sum(sizeof(pcap_usb_header_mmapped),
hdr->data_len);
} else {
/*
* We got data.
*/
if (is_isochronous_transfer_completion(hdr)) {
/*
* For isochronous transfer completion
* events, hdr->urb_len doesn't take
* into account the way the data is
* put into the buffer, as it doesn't
* count any padding between the
* chunks of isochronous data, so
* we have to calculate the amount
* of data from the isochronous
* descriptors.
*/
pkth.len = incoming_isochronous_transfer_completed_len(&pkth, bp);
} else {
/*
* For everything else, the original
* data length is just the length of
* the memory-mapped Linux USB header
* plus hdr->urb_len; we use
* hdr->urb_len so that it includes
* data discarded by the USB monitor
* device due to its buffer being
* too small. Clamp the result at
* UINT_MAX, so it fits in an
* unsigned int.
*/
pkth.len = u_int_sum(sizeof(pcap_usb_header_mmapped),
hdr->urb_len);
}
}
pkth.ts.tv_sec = (time_t)hdr->ts_sec;
pkth.ts.tv_usec = hdr->ts_usec;
if (handle->fcode.bf_insns == NULL ||
pcapint_filter(handle->fcode.bf_insns, (u_char*) hdr,
pkth.len, pkth.caplen)) {
handlep->packets_read++;
callback(user, &pkth, (u_char*) hdr);
packets++;
}
}
/*
* If max_packets specifies "unlimited", we stop after
* the first chunk.
*/
if (PACKET_COUNT_IS_UNLIMITED(max_packets) ||
(packets >= max_packets))
break;
}
/* flush pending events*/
if (ioctl(handle->fd, MON_IOCH_MFLUSH, nflush) == -1) {
pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't mflush fd %d", handle->fd);
return -1;
}
return packets;
}
static void
usb_cleanup_linux_mmap(pcap_t* handle)
{
struct pcap_usb_linux *handlep = handle->priv;
/* if we have a memory-mapped buffer, unmap it */
if (handlep->mmapbuf != NULL) {
munmap(handlep->mmapbuf, handlep->mmapbuflen);
handlep->mmapbuf = NULL;
}
pcapint_cleanup_live_common(handle);
}
