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freebsd/sys/kern/kern_ktrace.c
John Baldwin f4114c3d7f Replace the ktrace queue's semaphore with a condition variable instead as
it is slightly more efficient since we already have a mutex to protect the
queue.  Ktrace originally used a semaphore more as a proof of concept.
2004-02-26 19:30:22 +00:00

908 lines
21 KiB
C

/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ktrace.h"
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/mac.h>
#include <sys/malloc.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/ktrace.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/sysproto.h>
static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
#ifdef KTRACE
#ifndef KTRACE_REQUEST_POOL
#define KTRACE_REQUEST_POOL 100
#endif
struct ktr_request {
struct ktr_header ktr_header;
struct ucred *ktr_cred;
struct vnode *ktr_vp;
union {
struct ktr_syscall ktr_syscall;
struct ktr_sysret ktr_sysret;
struct ktr_genio ktr_genio;
struct ktr_psig ktr_psig;
struct ktr_csw ktr_csw;
} ktr_data;
STAILQ_ENTRY(ktr_request) ktr_list;
};
static int data_lengths[] = {
0, /* none */
offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */
sizeof(struct ktr_sysret), /* KTR_SYSRET */
0, /* KTR_NAMEI */
sizeof(struct ktr_genio), /* KTR_GENIO */
sizeof(struct ktr_psig), /* KTR_PSIG */
sizeof(struct ktr_csw), /* KTR_CSW */
0 /* KTR_USER */
};
static STAILQ_HEAD(, ktr_request) ktr_todo;
static STAILQ_HEAD(, ktr_request) ktr_free;
SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options");
static u_int ktr_requestpool = KTRACE_REQUEST_POOL;
TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool);
static u_int ktr_geniosize = PAGE_SIZE;
TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize);
SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize,
0, "Maximum size of genio event payload");
static int print_message = 1;
struct mtx ktrace_mtx;
static struct cv ktrace_cv;
static void ktrace_init(void *dummy);
static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
static u_int ktrace_resize_pool(u_int newsize);
static struct ktr_request *ktr_getrequest(int type);
static void ktr_submitrequest(struct ktr_request *req);
static void ktr_freerequest(struct ktr_request *req);
static void ktr_loop(void *dummy);
static void ktr_writerequest(struct ktr_request *req);
static int ktrcanset(struct thread *,struct proc *);
static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *);
static int ktrops(struct thread *,struct proc *,int,int,struct vnode *);
static void
ktrace_init(void *dummy)
{
struct ktr_request *req;
int i;
mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
cv_init(&ktrace_cv, "ktrace");
STAILQ_INIT(&ktr_todo);
STAILQ_INIT(&ktr_free);
for (i = 0; i < ktr_requestpool; i++) {
req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK);
STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
}
kthread_create(ktr_loop, NULL, NULL, RFHIGHPID, 0, "ktrace");
}
SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL);
static int
sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
{
struct thread *td;
u_int newsize, oldsize, wantsize;
int error;
/* Handle easy read-only case first to avoid warnings from GCC. */
if (!req->newptr) {
mtx_lock(&ktrace_mtx);
oldsize = ktr_requestpool;
mtx_unlock(&ktrace_mtx);
return (SYSCTL_OUT(req, &oldsize, sizeof(u_int)));
}
error = SYSCTL_IN(req, &wantsize, sizeof(u_int));
if (error)
return (error);
td = curthread;
td->td_pflags |= TDP_INKTRACE;
mtx_lock(&ktrace_mtx);
oldsize = ktr_requestpool;
newsize = ktrace_resize_pool(wantsize);
mtx_unlock(&ktrace_mtx);
td->td_pflags &= ~TDP_INKTRACE;
error = SYSCTL_OUT(req, &oldsize, sizeof(u_int));
if (error)
return (error);
if (wantsize > oldsize && newsize < wantsize)
return (ENOSPC);
return (0);
}
SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW,
&ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", "");
static u_int
ktrace_resize_pool(u_int newsize)
{
struct ktr_request *req;
int bound;
mtx_assert(&ktrace_mtx, MA_OWNED);
print_message = 1;
bound = newsize - ktr_requestpool;
if (bound == 0)
return (ktr_requestpool);
if (bound < 0)
/* Shrink pool down to newsize if possible. */
while (bound++ < 0) {
req = STAILQ_FIRST(&ktr_free);
if (req == NULL)
return (ktr_requestpool);
STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
ktr_requestpool--;
mtx_unlock(&ktrace_mtx);
free(req, M_KTRACE);
mtx_lock(&ktrace_mtx);
}
else
/* Grow pool up to newsize. */
while (bound-- > 0) {
mtx_unlock(&ktrace_mtx);
req = malloc(sizeof(struct ktr_request), M_KTRACE,
M_WAITOK);
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
ktr_requestpool++;
}
return (ktr_requestpool);
}
static struct ktr_request *
ktr_getrequest(int type)
{
struct ktr_request *req;
struct thread *td = curthread;
struct proc *p = td->td_proc;
int pm;
td->td_pflags |= TDP_INKTRACE;
mtx_lock(&ktrace_mtx);
if (!KTRCHECK(td, type)) {
mtx_unlock(&ktrace_mtx);
td->td_pflags &= ~TDP_INKTRACE;
return (NULL);
}
req = STAILQ_FIRST(&ktr_free);
if (req != NULL) {
STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
req->ktr_header.ktr_type = type;
if (p->p_traceflag & KTRFAC_DROP) {
req->ktr_header.ktr_type |= KTR_DROP;
p->p_traceflag &= ~KTRFAC_DROP;
}
KASSERT(p->p_tracevp != NULL, ("ktrace: no trace vnode"));
KASSERT(p->p_tracecred != NULL, ("ktrace: no trace cred"));
req->ktr_vp = p->p_tracevp;
VREF(p->p_tracevp);
req->ktr_cred = crhold(p->p_tracecred);
mtx_unlock(&ktrace_mtx);
microtime(&req->ktr_header.ktr_time);
req->ktr_header.ktr_pid = p->p_pid;
bcopy(p->p_comm, req->ktr_header.ktr_comm, MAXCOMLEN + 1);
req->ktr_header.ktr_buffer = NULL;
req->ktr_header.ktr_len = 0;
} else {
p->p_traceflag |= KTRFAC_DROP;
pm = print_message;
print_message = 0;
mtx_unlock(&ktrace_mtx);
if (pm)
printf("Out of ktrace request objects.\n");
td->td_pflags &= ~TDP_INKTRACE;
}
return (req);
}
static void
ktr_submitrequest(struct ktr_request *req)
{
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_TAIL(&ktr_todo, req, ktr_list);
cv_signal(&ktrace_cv);
mtx_unlock(&ktrace_mtx);
curthread->td_pflags &= ~TDP_INKTRACE;
}
static void
ktr_freerequest(struct ktr_request *req)
{
crfree(req->ktr_cred);
if (req->ktr_vp != NULL) {
mtx_lock(&Giant);
vrele(req->ktr_vp);
mtx_unlock(&Giant);
}
if (req->ktr_header.ktr_buffer != NULL)
free(req->ktr_header.ktr_buffer, M_KTRACE);
mtx_lock(&ktrace_mtx);
STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
mtx_unlock(&ktrace_mtx);
}
static void
ktr_loop(void *dummy)
{
struct ktr_request *req;
struct thread *td;
struct ucred *cred;
/* Only cache these values once. */
td = curthread;
cred = td->td_ucred;
for (;;) {
mtx_lock(&ktrace_mtx);
while (STAILQ_EMPTY(&ktr_todo))
cv_wait(&ktrace_cv, &ktrace_mtx);
req = STAILQ_FIRST(&ktr_todo);
STAILQ_REMOVE_HEAD(&ktr_todo, ktr_list);
KASSERT(req != NULL, ("got a NULL request"));
mtx_unlock(&ktrace_mtx);
/*
* It is not enough just to pass the cached cred
* to the VOP's in ktr_writerequest(). Some VFS
* operations use curthread->td_ucred, so we need
* to modify our thread's credentials as well.
* Evil.
*/
td->td_ucred = req->ktr_cred;
ktr_writerequest(req);
td->td_ucred = cred;
ktr_freerequest(req);
}
}
/*
* MPSAFE
*/
void
ktrsyscall(code, narg, args)
int code, narg;
register_t args[];
{
struct ktr_request *req;
struct ktr_syscall *ktp;
size_t buflen;
char *buf = NULL;
buflen = sizeof(register_t) * narg;
if (buflen > 0) {
buf = malloc(buflen, M_KTRACE, M_WAITOK);
bcopy(args, buf, buflen);
}
req = ktr_getrequest(KTR_SYSCALL);
if (req == NULL) {
if (buf != NULL)
free(buf, M_KTRACE);
return;
}
ktp = &req->ktr_data.ktr_syscall;
ktp->ktr_code = code;
ktp->ktr_narg = narg;
if (buflen > 0) {
req->ktr_header.ktr_len = buflen;
req->ktr_header.ktr_buffer = buf;
}
ktr_submitrequest(req);
}
/*
* MPSAFE
*/
void
ktrsysret(code, error, retval)
int code, error;
register_t retval;
{
struct ktr_request *req;
struct ktr_sysret *ktp;
req = ktr_getrequest(KTR_SYSRET);
if (req == NULL)
return;
ktp = &req->ktr_data.ktr_sysret;
ktp->ktr_code = code;
ktp->ktr_error = error;
ktp->ktr_retval = retval; /* what about val2 ? */
ktr_submitrequest(req);
}
void
ktrnamei(path)
char *path;
{
struct ktr_request *req;
int namelen;
char *buf = NULL;
namelen = strlen(path);
if (namelen > 0) {
buf = malloc(namelen, M_KTRACE, M_WAITOK);
bcopy(path, buf, namelen);
}
req = ktr_getrequest(KTR_NAMEI);
if (req == NULL) {
if (buf != NULL)
free(buf, M_KTRACE);
return;
}
if (namelen > 0) {
req->ktr_header.ktr_len = namelen;
req->ktr_header.ktr_buffer = buf;
}
ktr_submitrequest(req);
}
/*
* Since the uio may not stay valid, we can not hand off this request to
* the thread and need to process it synchronously. However, we wish to
* keep the relative order of records in a trace file correct, so we
* do put this request on the queue (if it isn't empty) and then block.
* The ktrace thread waks us back up when it is time for this event to
* be posted and blocks until we have completed writing out the event
* and woken it back up.
*/
void
ktrgenio(fd, rw, uio, error)
int fd;
enum uio_rw rw;
struct uio *uio;
int error;
{
struct ktr_request *req;
struct ktr_genio *ktg;
int datalen;
char *buf;
if (error)
return;
uio->uio_offset = 0;
uio->uio_rw = UIO_WRITE;
datalen = imin(uio->uio_resid, ktr_geniosize);
buf = malloc(datalen, M_KTRACE, M_WAITOK);
if (uiomove(buf, datalen, uio)) {
free(buf, M_KTRACE);
return;
}
req = ktr_getrequest(KTR_GENIO);
if (req == NULL) {
free(buf, M_KTRACE);
return;
}
ktg = &req->ktr_data.ktr_genio;
ktg->ktr_fd = fd;
ktg->ktr_rw = rw;
req->ktr_header.ktr_len = datalen;
req->ktr_header.ktr_buffer = buf;
ktr_submitrequest(req);
}
void
ktrpsig(sig, action, mask, code)
int sig;
sig_t action;
sigset_t *mask;
int code;
{
struct ktr_request *req;
struct ktr_psig *kp;
req = ktr_getrequest(KTR_PSIG);
if (req == NULL)
return;
kp = &req->ktr_data.ktr_psig;
kp->signo = (char)sig;
kp->action = action;
kp->mask = *mask;
kp->code = code;
ktr_submitrequest(req);
}
void
ktrcsw(out, user)
int out, user;
{
struct ktr_request *req;
struct ktr_csw *kc;
req = ktr_getrequest(KTR_CSW);
if (req == NULL)
return;
kc = &req->ktr_data.ktr_csw;
kc->out = out;
kc->user = user;
ktr_submitrequest(req);
}
#endif /* KTRACE */
/* Interface and common routines */
/*
* ktrace system call
*
* MPSAFE
*/
#ifndef _SYS_SYSPROTO_H_
struct ktrace_args {
char *fname;
int ops;
int facs;
int pid;
};
#endif
/* ARGSUSED */
int
ktrace(td, uap)
struct thread *td;
register struct ktrace_args *uap;
{
#ifdef KTRACE
register struct vnode *vp = NULL;
register struct proc *p;
struct pgrp *pg;
int facs = uap->facs & ~KTRFAC_ROOT;
int ops = KTROP(uap->ops);
int descend = uap->ops & KTRFLAG_DESCEND;
int ret = 0;
int flags, error = 0;
struct nameidata nd;
struct ucred *cred;
/*
* Need something to (un)trace.
*/
if (ops != KTROP_CLEARFILE && facs == 0)
return (EINVAL);
td->td_pflags |= TDP_INKTRACE;
if (ops != KTROP_CLEAR) {
/*
* an operation which requires a file argument.
*/
NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->fname, td);
flags = FREAD | FWRITE | O_NOFOLLOW;
mtx_lock(&Giant);
error = vn_open(&nd, &flags, 0, -1);
if (error) {
mtx_unlock(&Giant);
td->td_pflags &= ~TDP_INKTRACE;
return (error);
}
NDFREE(&nd, NDF_ONLY_PNBUF);
vp = nd.ni_vp;
VOP_UNLOCK(vp, 0, td);
if (vp->v_type != VREG) {
(void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
mtx_unlock(&Giant);
td->td_pflags &= ~TDP_INKTRACE;
return (EACCES);
}
mtx_unlock(&Giant);
}
/*
* Clear all uses of the tracefile.
*/
if (ops == KTROP_CLEARFILE) {
sx_slock(&allproc_lock);
LIST_FOREACH(p, &allproc, p_list) {
PROC_LOCK(p);
if (p->p_tracevp == vp) {
if (ktrcanset(td, p)) {
mtx_lock(&ktrace_mtx);
cred = p->p_tracecred;
p->p_tracecred = NULL;
p->p_tracevp = NULL;
p->p_traceflag = 0;
mtx_unlock(&ktrace_mtx);
PROC_UNLOCK(p);
mtx_lock(&Giant);
(void) vn_close(vp, FREAD|FWRITE,
cred, td);
mtx_unlock(&Giant);
crfree(cred);
} else {
PROC_UNLOCK(p);
error = EPERM;
}
} else
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
goto done;
}
/*
* do it
*/
sx_slock(&proctree_lock);
if (uap->pid < 0) {
/*
* by process group
*/
pg = pgfind(-uap->pid);
if (pg == NULL) {
sx_sunlock(&proctree_lock);
error = ESRCH;
goto done;
}
/*
* ktrops() may call vrele(). Lock pg_members
* by the proctree_lock rather than pg_mtx.
*/
PGRP_UNLOCK(pg);
LIST_FOREACH(p, &pg->pg_members, p_pglist)
if (descend)
ret |= ktrsetchildren(td, p, ops, facs, vp);
else
ret |= ktrops(td, p, ops, facs, vp);
} else {
/*
* by pid
*/
p = pfind(uap->pid);
if (p == NULL) {
sx_sunlock(&proctree_lock);
error = ESRCH;
goto done;
}
/*
* The slock of the proctree lock will keep this process
* from going away, so unlocking the proc here is ok.
*/
PROC_UNLOCK(p);
if (descend)
ret |= ktrsetchildren(td, p, ops, facs, vp);
else
ret |= ktrops(td, p, ops, facs, vp);
}
sx_sunlock(&proctree_lock);
if (!ret)
error = EPERM;
done:
if (vp != NULL) {
mtx_lock(&Giant);
(void) vn_close(vp, FWRITE, td->td_ucred, td);
mtx_unlock(&Giant);
}
td->td_pflags &= ~TDP_INKTRACE;
return (error);
#else /* !KTRACE */
return (ENOSYS);
#endif /* KTRACE */
}
/*
* utrace system call
*
* MPSAFE
*/
/* ARGSUSED */
int
utrace(td, uap)
struct thread *td;
register struct utrace_args *uap;
{
#ifdef KTRACE
struct ktr_request *req;
void *cp;
int error;
if (!KTRPOINT(td, KTR_USER))
return (0);
if (uap->len > KTR_USER_MAXLEN)
return (EINVAL);
cp = malloc(uap->len, M_KTRACE, M_WAITOK);
error = copyin(uap->addr, cp, uap->len);
if (error) {
free(cp, M_KTRACE);
return (error);
}
req = ktr_getrequest(KTR_USER);
if (req == NULL) {
free(cp, M_KTRACE);
return (ENOMEM);
}
req->ktr_header.ktr_buffer = cp;
req->ktr_header.ktr_len = uap->len;
ktr_submitrequest(req);
return (0);
#else /* !KTRACE */
return (ENOSYS);
#endif /* KTRACE */
}
#ifdef KTRACE
static int
ktrops(td, p, ops, facs, vp)
struct thread *td;
struct proc *p;
int ops, facs;
struct vnode *vp;
{
struct vnode *tracevp = NULL;
struct ucred *tracecred = NULL;
PROC_LOCK(p);
if (!ktrcanset(td, p)) {
PROC_UNLOCK(p);
return (0);
}
mtx_lock(&ktrace_mtx);
if (ops == KTROP_SET) {
if (p->p_tracevp != vp) {
/*
* if trace file already in use, relinquish below
*/
tracevp = p->p_tracevp;
VREF(vp);
p->p_tracevp = vp;
}
if (p->p_tracecred != td->td_ucred) {
tracecred = p->p_tracecred;
p->p_tracecred = crhold(td->td_ucred);
}
p->p_traceflag |= facs;
if (td->td_ucred->cr_uid == 0)
p->p_traceflag |= KTRFAC_ROOT;
} else {
/* KTROP_CLEAR */
if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
/* no more tracing */
p->p_traceflag = 0;
tracevp = p->p_tracevp;
p->p_tracevp = NULL;
tracecred = p->p_tracecred;
p->p_tracecred = NULL;
}
}
mtx_unlock(&ktrace_mtx);
PROC_UNLOCK(p);
if (tracevp != NULL) {
mtx_lock(&Giant);
vrele(tracevp);
mtx_unlock(&Giant);
}
if (tracecred != NULL)
crfree(tracecred);
return (1);
}
static int
ktrsetchildren(td, top, ops, facs, vp)
struct thread *td;
struct proc *top;
int ops, facs;
struct vnode *vp;
{
register struct proc *p;
register int ret = 0;
p = top;
sx_assert(&proctree_lock, SX_LOCKED);
for (;;) {
ret |= ktrops(td, p, ops, facs, vp);
/*
* If this process has children, descend to them next,
* otherwise do any siblings, and if done with this level,
* follow back up the tree (but not past top).
*/
if (!LIST_EMPTY(&p->p_children))
p = LIST_FIRST(&p->p_children);
else for (;;) {
if (p == top)
return (ret);
if (LIST_NEXT(p, p_sibling)) {
p = LIST_NEXT(p, p_sibling);
break;
}
p = p->p_pptr;
}
}
/*NOTREACHED*/
}
static void
ktr_writerequest(struct ktr_request *req)
{
struct ktr_header *kth;
struct vnode *vp;
struct proc *p;
struct thread *td;
struct ucred *cred;
struct uio auio;
struct iovec aiov[3];
struct mount *mp;
int datalen, buflen, vrele_count;
int error;
vp = req->ktr_vp;
/*
* If vp is NULL, the vp has been cleared out from under this
* request, so just drop it.
*/
if (vp == NULL)
return;
kth = &req->ktr_header;
datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP];
buflen = kth->ktr_len;
cred = req->ktr_cred;
td = curthread;
auio.uio_iov = &aiov[0];
auio.uio_offset = 0;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_rw = UIO_WRITE;
aiov[0].iov_base = (caddr_t)kth;
aiov[0].iov_len = sizeof(struct ktr_header);
auio.uio_resid = sizeof(struct ktr_header);
auio.uio_iovcnt = 1;
auio.uio_td = td;
if (datalen != 0) {
aiov[1].iov_base = (caddr_t)&req->ktr_data;
aiov[1].iov_len = datalen;
auio.uio_resid += datalen;
auio.uio_iovcnt++;
kth->ktr_len += datalen;
}
if (buflen != 0) {
KASSERT(kth->ktr_buffer != NULL, ("ktrace: nothing to write"));
aiov[auio.uio_iovcnt].iov_base = kth->ktr_buffer;
aiov[auio.uio_iovcnt].iov_len = buflen;
auio.uio_resid += buflen;
auio.uio_iovcnt++;
}
mtx_lock(&Giant);
vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
(void)VOP_LEASE(vp, td, cred, LEASE_WRITE);
#ifdef MAC
error = mac_check_vnode_write(cred, NOCRED, vp);
if (error == 0)
#endif
error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
VOP_UNLOCK(vp, 0, td);
vn_finished_write(mp);
mtx_unlock(&Giant);
if (!error)
return;
/*
* If error encountered, give up tracing on this vnode. We defer
* all the vrele()'s on the vnode until after we are finished walking
* the various lists to avoid needlessly holding locks.
*/
log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
error);
vrele_count = 0;
/*
* First, clear this vnode from being used by any processes in the
* system.
* XXX - If one process gets an EPERM writing to the vnode, should
* we really do this? Other processes might have suitable
* credentials for the operation.
*/
cred = NULL;
sx_slock(&allproc_lock);
LIST_FOREACH(p, &allproc, p_list) {
PROC_LOCK(p);
if (p->p_tracevp == vp) {
mtx_lock(&ktrace_mtx);
p->p_tracevp = NULL;
p->p_traceflag = 0;
cred = p->p_tracecred;
p->p_tracecred = NULL;
mtx_unlock(&ktrace_mtx);
vrele_count++;
}
PROC_UNLOCK(p);
if (cred != NULL) {
crfree(cred);
cred = NULL;
}
}
sx_sunlock(&allproc_lock);
/*
* Second, clear this vnode from any pending requests.
*/
mtx_lock(&ktrace_mtx);
STAILQ_FOREACH(req, &ktr_todo, ktr_list) {
if (req->ktr_vp == vp) {
req->ktr_vp = NULL;
vrele_count++;
}
}
mtx_unlock(&ktrace_mtx);
mtx_lock(&Giant);
while (vrele_count-- > 0)
vrele(vp);
mtx_unlock(&Giant);
}
/*
* Return true if caller has permission to set the ktracing state
* of target. Essentially, the target can't possess any
* more permissions than the caller. KTRFAC_ROOT signifies that
* root previously set the tracing status on the target process, and
* so, only root may further change it.
*/
static int
ktrcanset(td, targetp)
struct thread *td;
struct proc *targetp;
{
PROC_LOCK_ASSERT(targetp, MA_OWNED);
if (targetp->p_traceflag & KTRFAC_ROOT &&
suser_cred(td->td_ucred, PRISON_ROOT))
return (0);
if (p_candebug(td, targetp) != 0)
return (0);
return (1);
}
#endif /* KTRACE */