2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California.
4 * Copyright (c) 2005 Robert N. M. Watson
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 4. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
37 #include "opt_ktrace.h"
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/fcntl.h>
42 #include <sys/kernel.h>
43 #include <sys/kthread.h>
45 #include <sys/mutex.h>
46 #include <sys/malloc.h>
47 #include <sys/mount.h>
48 #include <sys/namei.h>
51 #include <sys/unistd.h>
52 #include <sys/vnode.h>
53 #include <sys/socket.h>
55 #include <sys/ktrace.h>
57 #include <sys/sysctl.h>
58 #include <sys/syslog.h>
59 #include <sys/sysproto.h>
61 #include <security/mac/mac_framework.h>
64 * The ktrace facility allows the tracing of certain key events in user space
65 * processes, such as system calls, signal delivery, context switches, and
66 * user generated events using utrace(2). It works by streaming event
67 * records and data to a vnode associated with the process using the
68 * ktrace(2) system call. In general, records can be written directly from
69 * the context that generates the event. One important exception to this is
70 * during a context switch, where sleeping is not permitted. To handle this
71 * case, trace events are generated using in-kernel ktr_request records, and
72 * then delivered to disk at a convenient moment -- either immediately, the
73 * next traceable event, at system call return, or at process exit.
75 * When dealing with multiple threads or processes writing to the same event
76 * log, ordering guarantees are weak: specifically, if an event has multiple
77 * records (i.e., system call enter and return), they may be interlaced with
78 * records from another event. Process and thread ID information is provided
79 * in the record, and user applications can de-interlace events if required.
82 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
86 #ifndef KTRACE_REQUEST_POOL
87 #define KTRACE_REQUEST_POOL 100
91 struct ktr_header ktr_header;
94 struct ktr_syscall ktr_syscall;
95 struct ktr_sysret ktr_sysret;
96 struct ktr_genio ktr_genio;
97 struct ktr_psig ktr_psig;
98 struct ktr_csw ktr_csw;
100 STAILQ_ENTRY(ktr_request) ktr_list;
103 static int data_lengths[] = {
105 offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */
106 sizeof(struct ktr_sysret), /* KTR_SYSRET */
108 sizeof(struct ktr_genio), /* KTR_GENIO */
109 sizeof(struct ktr_psig), /* KTR_PSIG */
110 sizeof(struct ktr_csw), /* KTR_CSW */
116 static STAILQ_HEAD(, ktr_request) ktr_free;
118 static SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options");
120 static u_int ktr_requestpool = KTRACE_REQUEST_POOL;
121 TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool);
123 static u_int ktr_geniosize = PAGE_SIZE;
124 TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize);
125 SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize,
126 0, "Maximum size of genio event payload");
128 static int print_message = 1;
129 struct mtx ktrace_mtx;
130 static struct sx ktrace_sx;
132 static void ktrace_init(void *dummy);
133 static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
134 static u_int ktrace_resize_pool(u_int newsize);
135 static struct ktr_request *ktr_getrequest(int type);
136 static void ktr_submitrequest(struct thread *td, struct ktr_request *req);
137 static void ktr_freerequest(struct ktr_request *req);
138 static void ktr_writerequest(struct thread *td, struct ktr_request *req);
139 static int ktrcanset(struct thread *,struct proc *);
140 static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *);
141 static int ktrops(struct thread *,struct proc *,int,int,struct vnode *);
144 * ktrace itself generates events, such as context switches, which we do not
145 * wish to trace. Maintain a flag, TDP_INKTRACE, on each thread to determine
146 * whether or not it is in a region where tracing of events should be
150 ktrace_enter(struct thread *td)
153 KASSERT(!(td->td_pflags & TDP_INKTRACE), ("ktrace_enter: flag set"));
154 td->td_pflags |= TDP_INKTRACE;
158 ktrace_exit(struct thread *td)
161 KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_exit: flag not set"));
162 td->td_pflags &= ~TDP_INKTRACE;
166 ktrace_assert(struct thread *td)
169 KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_assert: flag not set"));
173 ktrace_init(void *dummy)
175 struct ktr_request *req;
178 mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
179 sx_init(&ktrace_sx, "ktrace_sx");
180 STAILQ_INIT(&ktr_free);
181 for (i = 0; i < ktr_requestpool; i++) {
182 req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK);
183 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
186 SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL);
189 sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
192 u_int newsize, oldsize, wantsize;
195 /* Handle easy read-only case first to avoid warnings from GCC. */
197 mtx_lock(&ktrace_mtx);
198 oldsize = ktr_requestpool;
199 mtx_unlock(&ktrace_mtx);
200 return (SYSCTL_OUT(req, &oldsize, sizeof(u_int)));
203 error = SYSCTL_IN(req, &wantsize, sizeof(u_int));
208 mtx_lock(&ktrace_mtx);
209 oldsize = ktr_requestpool;
210 newsize = ktrace_resize_pool(wantsize);
211 mtx_unlock(&ktrace_mtx);
213 error = SYSCTL_OUT(req, &oldsize, sizeof(u_int));
216 if (wantsize > oldsize && newsize < wantsize)
220 SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW,
221 &ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", "");
224 ktrace_resize_pool(u_int newsize)
226 struct ktr_request *req;
229 mtx_assert(&ktrace_mtx, MA_OWNED);
231 bound = newsize - ktr_requestpool;
233 return (ktr_requestpool);
235 /* Shrink pool down to newsize if possible. */
236 while (bound++ < 0) {
237 req = STAILQ_FIRST(&ktr_free);
239 return (ktr_requestpool);
240 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
242 mtx_unlock(&ktrace_mtx);
244 mtx_lock(&ktrace_mtx);
247 /* Grow pool up to newsize. */
248 while (bound-- > 0) {
249 mtx_unlock(&ktrace_mtx);
250 req = malloc(sizeof(struct ktr_request), M_KTRACE,
252 mtx_lock(&ktrace_mtx);
253 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
256 return (ktr_requestpool);
259 static struct ktr_request *
260 ktr_getrequest(int type)
262 struct ktr_request *req;
263 struct thread *td = curthread;
264 struct proc *p = td->td_proc;
267 ktrace_enter(td); /* XXX: In caller instead? */
268 mtx_lock(&ktrace_mtx);
269 if (!KTRCHECK(td, type)) {
270 mtx_unlock(&ktrace_mtx);
274 req = STAILQ_FIRST(&ktr_free);
276 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
277 req->ktr_header.ktr_type = type;
278 if (p->p_traceflag & KTRFAC_DROP) {
279 req->ktr_header.ktr_type |= KTR_DROP;
280 p->p_traceflag &= ~KTRFAC_DROP;
282 mtx_unlock(&ktrace_mtx);
283 microtime(&req->ktr_header.ktr_time);
284 req->ktr_header.ktr_pid = p->p_pid;
285 req->ktr_header.ktr_tid = td->td_tid;
286 bcopy(td->td_name, req->ktr_header.ktr_comm, MAXCOMLEN + 1);
287 req->ktr_buffer = NULL;
288 req->ktr_header.ktr_len = 0;
290 p->p_traceflag |= KTRFAC_DROP;
293 mtx_unlock(&ktrace_mtx);
295 printf("Out of ktrace request objects.\n");
302 * Some trace generation environments don't permit direct access to VFS,
303 * such as during a context switch where sleeping is not allowed. Under these
304 * circumstances, queue a request to the thread to be written asynchronously
308 ktr_enqueuerequest(struct thread *td, struct ktr_request *req)
311 mtx_lock(&ktrace_mtx);
312 STAILQ_INSERT_TAIL(&td->td_proc->p_ktr, req, ktr_list);
313 mtx_unlock(&ktrace_mtx);
318 * Drain any pending ktrace records from the per-thread queue to disk. This
319 * is used both internally before committing other records, and also on
320 * system call return. We drain all the ones we can find at the time when
321 * drain is requested, but don't keep draining after that as those events
322 * may be approximately "after" the current event.
325 ktr_drain(struct thread *td)
327 struct ktr_request *queued_req;
328 STAILQ_HEAD(, ktr_request) local_queue;
331 sx_assert(&ktrace_sx, SX_XLOCKED);
333 STAILQ_INIT(&local_queue); /* XXXRW: needed? */
335 if (!STAILQ_EMPTY(&td->td_proc->p_ktr)) {
336 mtx_lock(&ktrace_mtx);
337 STAILQ_CONCAT(&local_queue, &td->td_proc->p_ktr);
338 mtx_unlock(&ktrace_mtx);
340 while ((queued_req = STAILQ_FIRST(&local_queue))) {
341 STAILQ_REMOVE_HEAD(&local_queue, ktr_list);
342 ktr_writerequest(td, queued_req);
343 ktr_freerequest(queued_req);
349 * Submit a trace record for immediate commit to disk -- to be used only
350 * where entering VFS is OK. First drain any pending records that may have
351 * been cached in the thread.
354 ktr_submitrequest(struct thread *td, struct ktr_request *req)
359 sx_xlock(&ktrace_sx);
361 ktr_writerequest(td, req);
362 ktr_freerequest(req);
363 sx_xunlock(&ktrace_sx);
369 ktr_freerequest(struct ktr_request *req)
372 if (req->ktr_buffer != NULL)
373 free(req->ktr_buffer, M_KTRACE);
374 mtx_lock(&ktrace_mtx);
375 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
376 mtx_unlock(&ktrace_mtx);
380 ktrsyscall(code, narg, args)
384 struct ktr_request *req;
385 struct ktr_syscall *ktp;
389 buflen = sizeof(register_t) * narg;
391 buf = malloc(buflen, M_KTRACE, M_WAITOK);
392 bcopy(args, buf, buflen);
394 req = ktr_getrequest(KTR_SYSCALL);
400 ktp = &req->ktr_data.ktr_syscall;
401 ktp->ktr_code = code;
402 ktp->ktr_narg = narg;
404 req->ktr_header.ktr_len = buflen;
405 req->ktr_buffer = buf;
407 ktr_submitrequest(curthread, req);
411 ktrsysret(code, error, retval)
415 struct ktr_request *req;
416 struct ktr_sysret *ktp;
418 req = ktr_getrequest(KTR_SYSRET);
421 ktp = &req->ktr_data.ktr_sysret;
422 ktp->ktr_code = code;
423 ktp->ktr_error = error;
424 ktp->ktr_retval = retval; /* what about val2 ? */
425 ktr_submitrequest(curthread, req);
429 * When a process exits, drain per-process asynchronous trace records.
432 ktrprocexit(struct thread *td)
436 sx_xlock(&ktrace_sx);
438 sx_xunlock(&ktrace_sx);
443 * When a thread returns, drain any asynchronous records generated by the
447 ktruserret(struct thread *td)
451 sx_xlock(&ktrace_sx);
453 sx_xunlock(&ktrace_sx);
461 struct ktr_request *req;
465 namelen = strlen(path);
467 buf = malloc(namelen, M_KTRACE, M_WAITOK);
468 bcopy(path, buf, namelen);
470 req = ktr_getrequest(KTR_NAMEI);
477 req->ktr_header.ktr_len = namelen;
478 req->ktr_buffer = buf;
480 ktr_submitrequest(curthread, req);
484 ktrsysctl(name, namelen)
488 struct ktr_request *req;
489 u_int mib[CTL_MAXNAME + 2];
494 /* Lookup name of mib. */
495 KASSERT(namelen <= CTL_MAXNAME, ("sysctl MIB too long"));
498 bcopy(name, mib + 2, namelen * sizeof(*name));
500 mibname = malloc(mibnamelen, M_KTRACE, M_WAITOK);
501 error = kernel_sysctl(curthread, mib, namelen + 2, mibname, &mibnamelen,
502 NULL, 0, &mibnamelen, 0);
504 free(mibname, M_KTRACE);
507 req = ktr_getrequest(KTR_SYSCTL);
509 free(mibname, M_KTRACE);
512 req->ktr_header.ktr_len = mibnamelen;
513 req->ktr_buffer = mibname;
514 ktr_submitrequest(curthread, req);
518 ktrgenio(fd, rw, uio, error)
524 struct ktr_request *req;
525 struct ktr_genio *ktg;
534 uio->uio_rw = UIO_WRITE;
535 datalen = imin(uio->uio_resid, ktr_geniosize);
536 buf = malloc(datalen, M_KTRACE, M_WAITOK);
537 error = uiomove(buf, datalen, uio);
543 req = ktr_getrequest(KTR_GENIO);
548 ktg = &req->ktr_data.ktr_genio;
551 req->ktr_header.ktr_len = datalen;
552 req->ktr_buffer = buf;
553 ktr_submitrequest(curthread, req);
557 ktrpsig(sig, action, mask, code)
563 struct ktr_request *req;
566 req = ktr_getrequest(KTR_PSIG);
569 kp = &req->ktr_data.ktr_psig;
570 kp->signo = (char)sig;
574 ktr_enqueuerequest(curthread, req);
581 struct ktr_request *req;
584 req = ktr_getrequest(KTR_CSW);
587 kc = &req->ktr_data.ktr_csw;
590 ktr_enqueuerequest(curthread, req);
594 ktrstruct(name, namelen, data, datalen)
600 struct ktr_request *req;
606 buflen = namelen + 1 + datalen;
607 buf = malloc(buflen, M_KTRACE, M_WAITOK);
608 bcopy(name, buf, namelen);
610 bcopy(data, buf + namelen + 1, datalen);
611 if ((req = ktr_getrequest(KTR_STRUCT)) == NULL) {
615 req->ktr_buffer = buf;
616 req->ktr_header.ktr_len = buflen;
617 ktr_submitrequest(curthread, req);
621 /* Interface and common routines */
623 #ifndef _SYS_SYSPROTO_H_
635 register struct ktrace_args *uap;
638 register struct vnode *vp = NULL;
639 register struct proc *p;
641 int facs = uap->facs & ~KTRFAC_ROOT;
642 int ops = KTROP(uap->ops);
643 int descend = uap->ops & KTRFLAG_DESCEND;
645 int flags, error = 0, vfslocked;
650 * Need something to (un)trace.
652 if (ops != KTROP_CLEARFILE && facs == 0)
656 if (ops != KTROP_CLEAR) {
658 * an operation which requires a file argument.
660 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_USERSPACE,
662 flags = FREAD | FWRITE | O_NOFOLLOW;
663 error = vn_open(&nd, &flags, 0, NULL);
668 vfslocked = NDHASGIANT(&nd);
669 NDFREE(&nd, NDF_ONLY_PNBUF);
672 if (vp->v_type != VREG) {
673 (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
674 VFS_UNLOCK_GIANT(vfslocked);
678 VFS_UNLOCK_GIANT(vfslocked);
681 * Clear all uses of the tracefile.
683 if (ops == KTROP_CLEARFILE) {
687 sx_slock(&allproc_lock);
688 FOREACH_PROC_IN_SYSTEM(p) {
690 if (p->p_tracevp == vp) {
691 if (ktrcanset(td, p)) {
692 mtx_lock(&ktrace_mtx);
693 cred = p->p_tracecred;
694 p->p_tracecred = NULL;
697 mtx_unlock(&ktrace_mtx);
705 sx_sunlock(&allproc_lock);
706 if (vrele_count > 0) {
707 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
708 while (vrele_count-- > 0)
710 VFS_UNLOCK_GIANT(vfslocked);
717 sx_slock(&proctree_lock);
722 pg = pgfind(-uap->pid);
724 sx_sunlock(&proctree_lock);
729 * ktrops() may call vrele(). Lock pg_members
730 * by the proctree_lock rather than pg_mtx.
734 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
736 if (p_cansee(td, p) != 0) {
743 ret |= ktrsetchildren(td, p, ops, facs, vp);
745 ret |= ktrops(td, p, ops, facs, vp);
748 sx_sunlock(&proctree_lock);
758 sx_sunlock(&proctree_lock);
762 error = p_cansee(td, p);
764 * The slock of the proctree lock will keep this process
765 * from going away, so unlocking the proc here is ok.
769 sx_sunlock(&proctree_lock);
773 ret |= ktrsetchildren(td, p, ops, facs, vp);
775 ret |= ktrops(td, p, ops, facs, vp);
777 sx_sunlock(&proctree_lock);
782 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
783 (void) vn_close(vp, FWRITE, td->td_ucred, td);
784 VFS_UNLOCK_GIANT(vfslocked);
797 register struct utrace_args *uap;
801 struct ktr_request *req;
805 if (!KTRPOINT(td, KTR_USER))
807 if (uap->len > KTR_USER_MAXLEN)
809 cp = malloc(uap->len, M_KTRACE, M_WAITOK);
810 error = copyin(uap->addr, cp, uap->len);
815 req = ktr_getrequest(KTR_USER);
820 req->ktr_buffer = cp;
821 req->ktr_header.ktr_len = uap->len;
822 ktr_submitrequest(td, req);
831 ktrops(td, p, ops, facs, vp)
837 struct vnode *tracevp = NULL;
838 struct ucred *tracecred = NULL;
841 if (!ktrcanset(td, p)) {
845 mtx_lock(&ktrace_mtx);
846 if (ops == KTROP_SET) {
847 if (p->p_tracevp != vp) {
849 * if trace file already in use, relinquish below
851 tracevp = p->p_tracevp;
855 if (p->p_tracecred != td->td_ucred) {
856 tracecred = p->p_tracecred;
857 p->p_tracecred = crhold(td->td_ucred);
859 p->p_traceflag |= facs;
860 if (priv_check(td, PRIV_KTRACE) == 0)
861 p->p_traceflag |= KTRFAC_ROOT;
864 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
865 /* no more tracing */
867 tracevp = p->p_tracevp;
869 tracecred = p->p_tracecred;
870 p->p_tracecred = NULL;
873 mtx_unlock(&ktrace_mtx);
875 if (tracevp != NULL) {
878 vfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
880 VFS_UNLOCK_GIANT(vfslocked);
882 if (tracecred != NULL)
889 ktrsetchildren(td, top, ops, facs, vp)
895 register struct proc *p;
896 register int ret = 0;
899 sx_assert(&proctree_lock, SX_LOCKED);
901 ret |= ktrops(td, p, ops, facs, vp);
903 * If this process has children, descend to them next,
904 * otherwise do any siblings, and if done with this level,
905 * follow back up the tree (but not past top).
907 if (!LIST_EMPTY(&p->p_children))
908 p = LIST_FIRST(&p->p_children);
912 if (LIST_NEXT(p, p_sibling)) {
913 p = LIST_NEXT(p, p_sibling);
923 ktr_writerequest(struct thread *td, struct ktr_request *req)
925 struct ktr_header *kth;
930 struct iovec aiov[3];
932 int datalen, buflen, vrele_count;
933 int error, vfslocked;
936 * We hold the vnode and credential for use in I/O in case ktrace is
937 * disabled on the process as we write out the request.
939 * XXXRW: This is not ideal: we could end up performing a write after
940 * the vnode has been closed.
942 mtx_lock(&ktrace_mtx);
943 vp = td->td_proc->p_tracevp;
944 cred = td->td_proc->p_tracecred;
947 * If vp is NULL, the vp has been cleared out from under this
948 * request, so just drop it. Make sure the credential and vnode are
949 * in sync: we should have both or neither.
952 KASSERT(cred == NULL, ("ktr_writerequest: cred != NULL"));
953 mtx_unlock(&ktrace_mtx);
957 KASSERT(cred != NULL, ("ktr_writerequest: cred == NULL"));
959 mtx_unlock(&ktrace_mtx);
961 kth = &req->ktr_header;
962 KASSERT(((u_short)kth->ktr_type & ~KTR_DROP) <
963 sizeof(data_lengths) / sizeof(data_lengths[0]),
964 ("data_lengths array overflow"));
965 datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP];
966 buflen = kth->ktr_len;
967 auio.uio_iov = &aiov[0];
969 auio.uio_segflg = UIO_SYSSPACE;
970 auio.uio_rw = UIO_WRITE;
971 aiov[0].iov_base = (caddr_t)kth;
972 aiov[0].iov_len = sizeof(struct ktr_header);
973 auio.uio_resid = sizeof(struct ktr_header);
977 aiov[1].iov_base = (caddr_t)&req->ktr_data;
978 aiov[1].iov_len = datalen;
979 auio.uio_resid += datalen;
981 kth->ktr_len += datalen;
984 KASSERT(req->ktr_buffer != NULL, ("ktrace: nothing to write"));
985 aiov[auio.uio_iovcnt].iov_base = req->ktr_buffer;
986 aiov[auio.uio_iovcnt].iov_len = buflen;
987 auio.uio_resid += buflen;
991 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
992 vn_start_write(vp, &mp, V_WAIT);
993 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
995 error = mac_vnode_check_write(cred, NOCRED, vp);
998 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
1000 vn_finished_write(mp);
1004 VFS_UNLOCK_GIANT(vfslocked);
1007 VFS_UNLOCK_GIANT(vfslocked);
1010 * If error encountered, give up tracing on this vnode. We defer
1011 * all the vrele()'s on the vnode until after we are finished walking
1012 * the various lists to avoid needlessly holding locks.
1013 * NB: at this point we still hold the vnode reference that must
1014 * not go away as we need the valid vnode to compare with. Thus let
1015 * vrele_count start at 1 and the reference will be freed
1016 * by the loop at the end after our last use of vp.
1018 log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
1022 * First, clear this vnode from being used by any processes in the
1024 * XXX - If one process gets an EPERM writing to the vnode, should
1025 * we really do this? Other processes might have suitable
1026 * credentials for the operation.
1029 sx_slock(&allproc_lock);
1030 FOREACH_PROC_IN_SYSTEM(p) {
1032 if (p->p_tracevp == vp) {
1033 mtx_lock(&ktrace_mtx);
1034 p->p_tracevp = NULL;
1036 cred = p->p_tracecred;
1037 p->p_tracecred = NULL;
1038 mtx_unlock(&ktrace_mtx);
1047 sx_sunlock(&allproc_lock);
1050 * We can't clear any pending requests in threads that have cached
1051 * them but not yet committed them, as those are per-thread. The
1052 * thread will have to clear it itself on system call return.
1054 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
1055 while (vrele_count-- > 0)
1057 VFS_UNLOCK_GIANT(vfslocked);
1061 * Return true if caller has permission to set the ktracing state
1062 * of target. Essentially, the target can't possess any
1063 * more permissions than the caller. KTRFAC_ROOT signifies that
1064 * root previously set the tracing status on the target process, and
1065 * so, only root may further change it.
1068 ktrcanset(td, targetp)
1070 struct proc *targetp;
1073 PROC_LOCK_ASSERT(targetp, MA_OWNED);
1074 if (targetp->p_traceflag & KTRFAC_ROOT &&
1075 priv_check(td, PRIV_KTRACE))
1078 if (p_candebug(td, targetp) != 0)