* Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.

/* $NetBSD: nfs_lock.c,v 1.3 2020/01/02 15:42:26 thorpej Exp $ */
/*-
* Copyright (c) 1997 Berkeley Software Design, Inc. 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. Berkeley Software Design Inc's name may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.
*
* from BSDI nfs_lock.c,v 2.4 1998/12/14 23:49:56 jch Exp
*/

#include <sys/cdefs.h>
/* __FBSDID("FreeBSD: head/sys/nfs/nfs_lock.c 303382 2016-07-27 11:08:59Z kib "); */
__RCSID("$NetBSD: nfs_lock.c,v 1.3 2020/01/02 15:42:26 thorpej Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/kernel.h> /* for hz */
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/lockf.h> /* for hz */ /* Must come after sys/malloc.h */
#include <sys/mbuf.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/socket.h>
#include <sys/socket.h>
#include <sys/unistd.h>
#include <sys/vnode.h>

#include <net/if.h>

#include <fs/nfs/common/nfsproto.h>
#include <fs/nfs/common/nfs_lock.h>
#include <fs/nfs/client/nfs.h>
#include <fs/nfs/client/nfsmount.h>
#include <fs/nfs/client/nfsnode.h>
#include <fs/nfs/client/nlminfo.h>

extern void (*nlminfo_release_p)(struct proc *p);

vop_advlock_t *nfs_advlock_p = nfs_dolock;
vop_reclaim_t *nfs_reclaim_p = NULL;

static MALLOC_DEFINE(M_NFSLOCK, "nfsclient_lock", "NFS lock request");
static MALLOC_DEFINE(M_NLMINFO, "nfsclient_nlminfo",
"NFS lock process structure");

static int nfslockdans(struct thread *td, struct lockd_ans *ansp);
static void nlminfo_release(struct proc *p);
/*
* --------------------------------------------------------------------
* A miniature device driver which the userland uses to talk to us.
*
*/

static struct cdev *nfslock_dev;
static struct mtx nfslock_mtx;
static int nfslock_isopen;
static TAILQ_HEAD(,__lock_msg) nfslock_list;

static int
nfslock_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
int error;

error = priv_check(td, PRIV_NFS_LOCKD);
if (error)
return (error);

mtx_lock(&nfslock_mtx);
if (!nfslock_isopen) {
error = 0;
nfslock_isopen = 1;
} else {
error = EOPNOTSUPP;
}
mtx_unlock(&nfslock_mtx);

return (error);
}

static int
nfslock_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
{
struct __lock_msg *lm;

mtx_lock(&nfslock_mtx);
nfslock_isopen = 0;
while (!TAILQ_EMPTY(&nfslock_list)) {
lm = TAILQ_FIRST(&nfslock_list);
/* XXX: answer request */
TAILQ_REMOVE(&nfslock_list, lm, lm_link);
free(lm, M_NFSLOCK);
}
mtx_unlock(&nfslock_mtx);
return (0);
}

static int
nfslock_read(struct cdev *dev, struct uio *uio, int ioflag)
{
int error;
struct __lock_msg *lm;

if (uio->uio_resid != sizeof *lm)
return (EOPNOTSUPP);
lm = NULL;
error = 0;
mtx_lock(&nfslock_mtx);
while (TAILQ_EMPTY(&nfslock_list)) {
error = msleep(&nfslock_list, &nfslock_mtx, PSOCK | PCATCH,
"nfslockd", 0);
if (error)
break;
}
if (!error) {
lm = TAILQ_FIRST(&nfslock_list);
TAILQ_REMOVE(&nfslock_list, lm, lm_link);
}
mtx_unlock(&nfslock_mtx);
if (!error) {
error = uiomove(lm, sizeof *lm, uio);
free(lm, M_NFSLOCK);
}
return (error);
}

static int
nfslock_write(struct cdev *dev, struct uio *uio, int ioflag)
{
struct lockd_ans la;
int error;

if (uio->uio_resid != sizeof la)
return (EOPNOTSUPP);
error = uiomove(&la, sizeof la, uio);
if (!error)
error = nfslockdans(curthread, &la);
return (error);
}

static int
nfslock_send(struct __lock_msg *lm)
{
struct __lock_msg *lm2;
int error;

error = 0;
lm2 = malloc(sizeof *lm2, M_NFSLOCK, M_WAITOK);
mtx_lock(&nfslock_mtx);
if (nfslock_isopen) {
memcpy(lm2, lm, sizeof *lm2);
TAILQ_INSERT_TAIL(&nfslock_list, lm2, lm_link);
wakeup(&nfslock_list);
} else {
error = EOPNOTSUPP;
}
mtx_unlock(&nfslock_mtx);
if (error)
free(lm2, M_NFSLOCK);
return (error);
}

static struct cdevsw nfslock_cdevsw = {
.d_version = D_VERSION,
.d_open = nfslock_open,
.d_close = nfslock_close,
.d_read = nfslock_read,
.d_write = nfslock_write,
.d_name = "nfslock"
};

static int
nfslock_modevent(module_t mod __unused, int type, void *data __unused)
{

switch (type) {
case MOD_LOAD:
if (bootverbose)
printf("nfslock: pseudo-device\n");
mtx_init(&nfslock_mtx, "nfslock", NULL, MTX_DEF);
TAILQ_INIT(&nfslock_list);
nlminfo_release_p = nlminfo_release;
nfslock_dev = make_dev(&nfslock_cdevsw, 0,
UID_ROOT, GID_KMEM, 0600, _PATH_NFSLCKDEV);
return (0);
default:
return (EOPNOTSUPP);
}
}

DEV_MODULE(nfslock, nfslock_modevent, NULL);
MODULE_VERSION(nfslock, 1);

/*
* XXX
* We have to let the process know if the call succeeded. I'm using an extra
* field in the p_nlminfo field in the proc structure, as it is already for
* lockd stuff.
*/

/*
* nfs_advlock --
* NFS advisory byte-level locks.
*
* The vnode shall be (shared) locked on the entry, it is
* unconditionally unlocked after.
*/
int
nfs_dolock(struct vop_advlock_args *ap)
{
LOCKD_MSG msg;
struct thread *td;
struct vnode *vp;
int error;
struct flock *fl;
struct proc *p;
struct nfsmount *nmp;
struct timeval btv;

td = curthread;
p = td->td_proc;

vp = ap->a_vp;
fl = ap->a_fl;
nmp = VFSTONFS(vp->v_mount);

ASSERT_VOP_LOCKED(vp, "nfs_dolock");

nmp->nm_getinfo(vp, msg.lm_fh, &msg.lm_fh_len, &msg.lm_addr,
&msg.lm_nfsv3, NULL, NULL);
VOP_UNLOCK(vp, 0);

/*
* the NLM protocol doesn't allow the server to return an error
* on ranges, so we do it.
*/
if (fl->l_whence != SEEK_END) {
if ((fl->l_whence != SEEK_CUR && fl->l_whence != SEEK_SET) ||
fl->l_start < 0 ||
(fl->l_len < 0 &&
(fl->l_start == 0 || fl->l_start + fl->l_len < 0)))
return (EINVAL);
if (fl->l_len > 0 &&
(fl->l_len - 1 > OFF_MAX - fl->l_start))
return (EOVERFLOW);
}

/*
* Fill in the information structure.
*/
msg.lm_version = LOCKD_MSG_VERSION;
msg.lm_msg_ident.pid = p->p_pid;

mtx_lock(&Giant);
/*
* if there is no nfsowner table yet, allocate one.
*/
if (p->p_nlminfo == NULL) {
p->p_nlminfo = malloc(sizeof(struct nlminfo),
M_NLMINFO, M_WAITOK | M_ZERO);
p->p_nlminfo->pid_start = p->p_stats->p_start;
getmicroboottime(&btv);
timevaladd(&p->p_nlminfo->pid_start, &btv);
}
msg.lm_msg_ident.pid_start = p->p_nlminfo->pid_start;
msg.lm_msg_ident.msg_seq = ++(p->p_nlminfo->msg_seq);

msg.lm_fl = *fl;
msg.lm_wait = ap->a_flags & F_WAIT;
msg.lm_getlk = ap->a_op == F_GETLK;
cru2x(td->td_ucred, &msg.lm_cred);

for (;;) {
error = nfslock_send(&msg);
if (error)
goto out;

/* Unlocks succeed immediately. */
if (fl->l_type == F_UNLCK)
goto out;

/*
* Retry after 20 seconds if we haven't gotten a response yet.
* This number was picked out of thin air... but is longer
* then even a reasonably loaded system should take (at least
* on a local network). XXX Probably should use a back-off
* scheme.
*
* XXX: No PCATCH here since we currently have no useful
* way to signal to the userland rpc.lockd that the request
* has been aborted. Once the rpc.lockd implementation
* can handle aborts, and we report them properly,
* PCATCH can be put back. In the mean time, if we did
* permit aborting, the lock attempt would "get lost"
* and the lock would get stuck in the locked state.
*/
error = tsleep(p->p_nlminfo, PUSER, "lockd", 20*hz);
if (error != 0) {
if (error == EWOULDBLOCK) {
/*
* We timed out, so we rewrite the request
* to the fifo.
*/
continue;
}

break;
}

if (msg.lm_getlk && p->p_nlminfo->retcode == 0) {
if (p->p_nlminfo->set_getlk_pid) {
fl->l_sysid = 0; /* XXX */
fl->l_pid = p->p_nlminfo->getlk_pid;
} else {
fl->l_type = F_UNLCK;
}
}
error = p->p_nlminfo->retcode;
break;
}
out:
mtx_unlock(&Giant);
return (error);
}

/*
* nfslockdans --
* NFS advisory byte-level locks answer from the lock daemon.
*/
static int
nfslockdans(struct thread *td, struct lockd_ans *ansp)
{
struct proc *targetp;

/* the version should match, or we're out of sync */
if (ansp->la_vers != LOCKD_ANS_VERSION)
return (EINVAL);

/* Find the process, set its return errno and wake it up. */
if ((targetp = pfind(ansp->la_msg_ident.pid)) == NULL)
return (ESRCH);

/* verify the pid hasn't been reused (if we can), and it isn't waiting
* for an answer from a more recent request. We return an EPIPE if
* the match fails, because we've already used ESRCH above, and this
* is sort of like writing on a pipe after the reader has closed it.
*/
if (targetp->p_nlminfo == NULL ||
((ansp->la_msg_ident.msg_seq != -1) &&
(timevalcmp(&targetp->p_nlminfo->pid_start,
&ansp->la_msg_ident.pid_start, !=) ||
targetp->p_nlminfo->msg_seq != ansp->la_msg_ident.msg_seq))) {
PROC_UNLOCK(targetp);
return (EPIPE);
}

targetp->p_nlminfo->retcode = ansp->la_errno;
targetp->p_nlminfo->set_getlk_pid = ansp->la_set_getlk_pid;
targetp->p_nlminfo->getlk_pid = ansp->la_getlk_pid;

wakeup(targetp->p_nlminfo);

PROC_UNLOCK(targetp);
return (0);
}

/*
* Free nlminfo attached to process.
*/
void
nlminfo_release(struct proc *p)
{
free(p->p_nlminfo, M_NLMINFO);
p->p_nlminfo = NULL;
}