1 /*-
2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California.
4 * Copyright (c) 2005 Robert N. M. Watson
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
18 *
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
29 * SUCH DAMAGE.
30 *
31 * @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include "opt_ktrace.h"
38 #include "opt_mac.h"
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/fcntl.h>
43 #include <sys/kernel.h>
44 #include <sys/kthread.h>
45 #include <sys/lock.h>
46 #include <sys/mutex.h>
47 #include <sys/malloc.h>
48 #include <sys/mount.h>
49 #include <sys/namei.h>
50 #include <sys/priv.h>
51 #include <sys/proc.h>
52 #include <sys/unistd.h>
53 #include <sys/vnode.h>
54 #include <sys/ktrace.h>
55 #include <sys/sx.h>
56 #include <sys/sysctl.h>
57 #include <sys/syslog.h>
58 #include <sys/sysproto.h>
59
60 #include <security/mac/mac_framework.h>
61
62 /*
63 * The ktrace facility allows the tracing of certain key events in user space
64 * processes, such as system calls, signal delivery, context switches, and
65 * user generated events using utrace(2). It works by streaming event
66 * records and data to a vnode associated with the process using the
67 * ktrace(2) system call. In general, records can be written directly from
68 * the context that generates the event. One important exception to this is
69 * during a context switch, where sleeping is not permitted. To handle this
70 * case, trace events are generated using in-kernel ktr_request records, and
71 * then delivered to disk at a convenient moment -- either immediately, the
72 * next traceable event, at system call return, or at process exit.
73 *
74 * When dealing with multiple threads or processes writing to the same event
75 * log, ordering guarantees are weak: specifically, if an event has multiple
76 * records (i.e., system call enter and return), they may be interlaced with
77 * records from another event. Process and thread ID information is provided
78 * in the record, and user applications can de-interlace events if required.
79 */
80
81 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
82
83 #ifdef KTRACE
84
85 #ifndef KTRACE_REQUEST_POOL
86 #define KTRACE_REQUEST_POOL 100
87 #endif
88
89 struct ktr_request {
90 struct ktr_header ktr_header;
91 void *ktr_buffer;
92 union {
93 struct ktr_syscall ktr_syscall;
94 struct ktr_sysret ktr_sysret;
95 struct ktr_genio ktr_genio;
96 struct ktr_psig ktr_psig;
97 struct ktr_csw ktr_csw;
98 } ktr_data;
99 STAILQ_ENTRY(ktr_request) ktr_list;
100 };
101
102 static int data_lengths[] = {
103 0, /* none */
104 offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */
105 sizeof(struct ktr_sysret), /* KTR_SYSRET */
106 0, /* KTR_NAMEI */
107 sizeof(struct ktr_genio), /* KTR_GENIO */
108 sizeof(struct ktr_psig), /* KTR_PSIG */
109 sizeof(struct ktr_csw), /* KTR_CSW */
110 0 /* KTR_USER */
111 };
112
113 static STAILQ_HEAD(, ktr_request) ktr_free;
114
115 static SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options");
116
117 static u_int ktr_requestpool = KTRACE_REQUEST_POOL;
118 TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool);
119
120 static u_int ktr_geniosize = PAGE_SIZE;
121 TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize);
122 SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize,
123 0, "Maximum size of genio event payload");
124
125 static int print_message = 1;
126 struct mtx ktrace_mtx;
127 static struct sx ktrace_sx;
128
129 static void ktrace_init(void *dummy);
130 static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
131 static u_int ktrace_resize_pool(u_int newsize);
132 static struct ktr_request *ktr_getrequest(int type);
133 static void ktr_submitrequest(struct thread *td, struct ktr_request *req);
134 static void ktr_freerequest(struct ktr_request *req);
135 static void ktr_writerequest(struct thread *td, struct ktr_request *req);
136 static int ktrcanset(struct thread *,struct proc *);
137 static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *);
138 static int ktrops(struct thread *,struct proc *,int,int,struct vnode *);
139
140 /*
141 * ktrace itself generates events, such as context switches, which we do not
142 * wish to trace. Maintain a flag, TDP_INKTRACE, on each thread to determine
143 * whether or not it is in a region where tracing of events should be
144 * suppressed.
145 */
146 static void
147 ktrace_enter(struct thread *td)
148 {
149
150 KASSERT(!(td->td_pflags & TDP_INKTRACE), ("ktrace_enter: flag set"));
151 td->td_pflags |= TDP_INKTRACE;
152 }
153
154 static void
155 ktrace_exit(struct thread *td)
156 {
157
158 KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_exit: flag not set"));
159 td->td_pflags &= ~TDP_INKTRACE;
160 }
161
162 static void
163 ktrace_assert(struct thread *td)
164 {
165
166 KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_assert: flag not set"));
167 }
168
169 static void
170 ktrace_init(void *dummy)
171 {
172 struct ktr_request *req;
173 int i;
174
175 mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
176 sx_init(&ktrace_sx, "ktrace_sx");
177 STAILQ_INIT(&ktr_free);
178 for (i = 0; i < ktr_requestpool; i++) {
179 req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK);
180 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
181 }
182 }
183 SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL);
184
185 static int
186 sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
187 {
188 struct thread *td;
189 u_int newsize, oldsize, wantsize;
190 int error;
191
192 /* Handle easy read-only case first to avoid warnings from GCC. */
193 if (!req->newptr) {
194 mtx_lock(&ktrace_mtx);
195 oldsize = ktr_requestpool;
196 mtx_unlock(&ktrace_mtx);
197 return (SYSCTL_OUT(req, &oldsize, sizeof(u_int)));
198 }
199
200 error = SYSCTL_IN(req, &wantsize, sizeof(u_int));
201 if (error)
202 return (error);
203 td = curthread;
204 ktrace_enter(td);
205 mtx_lock(&ktrace_mtx);
206 oldsize = ktr_requestpool;
207 newsize = ktrace_resize_pool(wantsize);
208 mtx_unlock(&ktrace_mtx);
209 ktrace_exit(td);
210 error = SYSCTL_OUT(req, &oldsize, sizeof(u_int));
211 if (error)
212 return (error);
213 if (wantsize > oldsize && newsize < wantsize)
214 return (ENOSPC);
215 return (0);
216 }
217 SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW,
218 &ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", "");
219
220 static u_int
221 ktrace_resize_pool(u_int newsize)
222 {
223 struct ktr_request *req;
224 int bound;
225
226 mtx_assert(&ktrace_mtx, MA_OWNED);
227 print_message = 1;
228 bound = newsize - ktr_requestpool;
229 if (bound == 0)
230 return (ktr_requestpool);
231 if (bound < 0)
232 /* Shrink pool down to newsize if possible. */
233 while (bound++ < 0) {
234 req = STAILQ_FIRST(&ktr_free);
235 if (req == NULL)
236 return (ktr_requestpool);
237 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
238 ktr_requestpool--;
239 mtx_unlock(&ktrace_mtx);
240 free(req, M_KTRACE);
241 mtx_lock(&ktrace_mtx);
242 }
243 else
244 /* Grow pool up to newsize. */
245 while (bound-- > 0) {
246 mtx_unlock(&ktrace_mtx);
247 req = malloc(sizeof(struct ktr_request), M_KTRACE,
248 M_WAITOK);
249 mtx_lock(&ktrace_mtx);
250 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
251 ktr_requestpool++;
252 }
253 return (ktr_requestpool);
254 }
255
256 static struct ktr_request *
257 ktr_getrequest(int type)
258 {
259 struct ktr_request *req;
260 struct thread *td = curthread;
261 struct proc *p = td->td_proc;
262 int pm;
263
264 ktrace_enter(td); /* XXX: In caller instead? */
265 mtx_lock(&ktrace_mtx);
266 if (!KTRCHECK(td, type)) {
267 mtx_unlock(&ktrace_mtx);
268 ktrace_exit(td);
269 return (NULL);
270 }
271 req = STAILQ_FIRST(&ktr_free);
272 if (req != NULL) {
273 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
274 req->ktr_header.ktr_type = type;
275 if (p->p_traceflag & KTRFAC_DROP) {
276 req->ktr_header.ktr_type |= KTR_DROP;
277 p->p_traceflag &= ~KTRFAC_DROP;
278 }
279 mtx_unlock(&ktrace_mtx);
280 microtime(&req->ktr_header.ktr_time);
281 req->ktr_header.ktr_pid = p->p_pid;
282 req->ktr_header.ktr_tid = td->td_tid;
283 bcopy(p->p_comm, req->ktr_header.ktr_comm, MAXCOMLEN + 1);
284 req->ktr_buffer = NULL;
285 req->ktr_header.ktr_len = 0;
286 } else {
287 p->p_traceflag |= KTRFAC_DROP;
288 pm = print_message;
289 print_message = 0;
290 mtx_unlock(&ktrace_mtx);
291 if (pm)
292 printf("Out of ktrace request objects.\n");
293 ktrace_exit(td);
294 }
295 return (req);
296 }
297
298 /*
299 * Some trace generation environments don't permit direct access to VFS,
300 * such as during a context switch where sleeping is not allowed. Under these
301 * circumstances, queue a request to the thread to be written asynchronously
302 * later.
303 */
304 static void
305 ktr_enqueuerequest(struct thread *td, struct ktr_request *req)
306 {
307
308 mtx_lock(&ktrace_mtx);
309 STAILQ_INSERT_TAIL(&td->td_proc->p_ktr, req, ktr_list);
310 mtx_unlock(&ktrace_mtx);
311 ktrace_exit(td);
312 }
313
314 /*
315 * Drain any pending ktrace records from the per-thread queue to disk. This
316 * is used both internally before committing other records, and also on
317 * system call return. We drain all the ones we can find at the time when
318 * drain is requested, but don't keep draining after that as those events
319 * may me approximately "after" the current event.
320 */
321 static void
322 ktr_drain(struct thread *td)
323 {
324 struct ktr_request *queued_req;
325 STAILQ_HEAD(, ktr_request) local_queue;
326
327 ktrace_assert(td);
328 sx_assert(&ktrace_sx, SX_XLOCKED);
329
330 STAILQ_INIT(&local_queue); /* XXXRW: needed? */
331
332 if (!STAILQ_EMPTY(&td->td_proc->p_ktr)) {
333 mtx_lock(&ktrace_mtx);
334 STAILQ_CONCAT(&local_queue, &td->td_proc->p_ktr);
335 mtx_unlock(&ktrace_mtx);
336
337 while ((queued_req = STAILQ_FIRST(&local_queue))) {
338 STAILQ_REMOVE_HEAD(&local_queue, ktr_list);
339 ktr_writerequest(td, queued_req);
340 ktr_freerequest(queued_req);
341 }
342 }
343 }
344
345 /*
346 * Submit a trace record for immediate commit to disk -- to be used only
347 * where entering VFS is OK. First drain any pending records that may have
348 * been cached in the thread.
349 */
350 static void
351 ktr_submitrequest(struct thread *td, struct ktr_request *req)
352 {
353
354 ktrace_assert(td);
355
356 sx_xlock(&ktrace_sx);
357 ktr_drain(td);
358 ktr_writerequest(td, req);
359 ktr_freerequest(req);
360 sx_xunlock(&ktrace_sx);
361
362 ktrace_exit(td);
363 }
364
365 static void
366 ktr_freerequest(struct ktr_request *req)
367 {
368
369 if (req->ktr_buffer != NULL)
370 free(req->ktr_buffer, M_KTRACE);
371 mtx_lock(&ktrace_mtx);
372 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
373 mtx_unlock(&ktrace_mtx);
374 }
375
376 void
377 ktrsyscall(code, narg, args)
378 int code, narg;
379 register_t args[];
380 {
381 struct ktr_request *req;
382 struct ktr_syscall *ktp;
383 size_t buflen;
384 char *buf = NULL;
385
386 buflen = sizeof(register_t) * narg;
387 if (buflen > 0) {
388 buf = malloc(buflen, M_KTRACE, M_WAITOK);
389 bcopy(args, buf, buflen);
390 }
391 req = ktr_getrequest(KTR_SYSCALL);
392 if (req == NULL) {
393 if (buf != NULL)
394 free(buf, M_KTRACE);
395 return;
396 }
397 ktp = &req->ktr_data.ktr_syscall;
398 ktp->ktr_code = code;
399 ktp->ktr_narg = narg;
400 if (buflen > 0) {
401 req->ktr_header.ktr_len = buflen;
402 req->ktr_buffer = buf;
403 }
404 ktr_submitrequest(curthread, req);
405 }
406
407 void
408 ktrsysret(code, error, retval)
409 int code, error;
410 register_t retval;
411 {
412 struct ktr_request *req;
413 struct ktr_sysret *ktp;
414
415 req = ktr_getrequest(KTR_SYSRET);
416 if (req == NULL)
417 return;
418 ktp = &req->ktr_data.ktr_sysret;
419 ktp->ktr_code = code;
420 ktp->ktr_error = error;
421 ktp->ktr_retval = retval; /* what about val2 ? */
422 ktr_submitrequest(curthread, req);
423 }
424
425 /*
426 * When a process exits, drain per-process asynchronous trace records.
427 */
428 void
429 ktrprocexit(struct thread *td)
430 {
431
432 ktrace_enter(td);
433 sx_xlock(&ktrace_sx);
434 ktr_drain(td);
435 sx_xunlock(&ktrace_sx);
436 ktrace_exit(td);
437 }
438
439 /*
440 * When a thread returns, drain any asynchronous records generated by the
441 * system call.
442 */
443 void
444 ktruserret(struct thread *td)
445 {
446
447 ktrace_enter(td);
448 sx_xlock(&ktrace_sx);
449 ktr_drain(td);
450 sx_xunlock(&ktrace_sx);
451 ktrace_exit(td);
452 }
453
454 void
455 ktrnamei(path)
456 char *path;
457 {
458 struct ktr_request *req;
459 int namelen;
460 char *buf = NULL;
461
462 namelen = strlen(path);
463 if (namelen > 0) {
464 buf = malloc(namelen, M_KTRACE, M_WAITOK);
465 bcopy(path, buf, namelen);
466 }
467 req = ktr_getrequest(KTR_NAMEI);
468 if (req == NULL) {
469 if (buf != NULL)
470 free(buf, M_KTRACE);
471 return;
472 }
473 if (namelen > 0) {
474 req->ktr_header.ktr_len = namelen;
475 req->ktr_buffer = buf;
476 }
477 ktr_submitrequest(curthread, req);
478 }
479
480 void
481 ktrgenio(fd, rw, uio, error)
482 int fd;
483 enum uio_rw rw;
484 struct uio *uio;
485 int error;
486 {
487 struct ktr_request *req;
488 struct ktr_genio *ktg;
489 int datalen;
490 char *buf;
491
492 if (error) {
493 free(uio, M_IOV);
494 return;
495 }
496 uio->uio_offset = 0;
497 uio->uio_rw = UIO_WRITE;
498 datalen = imin(uio->uio_resid, ktr_geniosize);
499 buf = malloc(datalen, M_KTRACE, M_WAITOK);
500 error = uiomove(buf, datalen, uio);
501 free(uio, M_IOV);
502 if (error) {
503 free(buf, M_KTRACE);
504 return;
505 }
506 req = ktr_getrequest(KTR_GENIO);
507 if (req == NULL) {
508 free(buf, M_KTRACE);
509 return;
510 }
511 ktg = &req->ktr_data.ktr_genio;
512 ktg->ktr_fd = fd;
513 ktg->ktr_rw = rw;
514 req->ktr_header.ktr_len = datalen;
515 req->ktr_buffer = buf;
516 ktr_submitrequest(curthread, req);
517 }
518
519 void
520 ktrpsig(sig, action, mask, code)
521 int sig;
522 sig_t action;
523 sigset_t *mask;
524 int code;
525 {
526 struct ktr_request *req;
527 struct ktr_psig *kp;
528
529 req = ktr_getrequest(KTR_PSIG);
530 if (req == NULL)
531 return;
532 kp = &req->ktr_data.ktr_psig;
533 kp->signo = (char)sig;
534 kp->action = action;
535 kp->mask = *mask;
536 kp->code = code;
537 ktr_enqueuerequest(curthread, req);
538 }
539
540 void
541 ktrcsw(out, user)
542 int out, user;
543 {
544 struct ktr_request *req;
545 struct ktr_csw *kc;
546
547 req = ktr_getrequest(KTR_CSW);
548 if (req == NULL)
549 return;
550 kc = &req->ktr_data.ktr_csw;
551 kc->out = out;
552 kc->user = user;
553 ktr_enqueuerequest(curthread, req);
554 }
555 #endif /* KTRACE */
556
557 /* Interface and common routines */
558
559 #ifndef _SYS_SYSPROTO_H_
560 struct ktrace_args {
561 char *fname;
562 int ops;
563 int facs;
564 int pid;
565 };
566 #endif
567 /* ARGSUSED */
568 int
569 ktrace(td, uap)
570 struct thread *td;
571 register struct ktrace_args *uap;
572 {
573 #ifdef KTRACE
574 register struct vnode *vp = NULL;
575 register struct proc *p;
576 struct pgrp *pg;
577 int facs = uap->facs & ~KTRFAC_ROOT;
578 int ops = KTROP(uap->ops);
579 int descend = uap->ops & KTRFLAG_DESCEND;
580 int nfound, ret = 0;
581 int flags, error = 0, vfslocked;
582 struct nameidata nd;
583 struct ucred *cred;
584
585 /*
586 * Need something to (un)trace.
587 */
588 if (ops != KTROP_CLEARFILE && facs == 0)
589 return (EINVAL);
590
591 ktrace_enter(td);
592 if (ops != KTROP_CLEAR) {
593 /*
594 * an operation which requires a file argument.
595 */
596 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_USERSPACE,
597 uap->fname, td);
598 flags = FREAD | FWRITE | O_NOFOLLOW;
599 error = vn_open(&nd, &flags, 0, NULL);
600 if (error) {
601 ktrace_exit(td);
602 return (error);
603 }
604 vfslocked = NDHASGIANT(&nd);
605 NDFREE(&nd, NDF_ONLY_PNBUF);
606 vp = nd.ni_vp;
607 VOP_UNLOCK(vp, 0, td);
608 if (vp->v_type != VREG) {
609 (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
610 VFS_UNLOCK_GIANT(vfslocked);
611 ktrace_exit(td);
612 return (EACCES);
613 }
614 VFS_UNLOCK_GIANT(vfslocked);
615 }
616 /*
617 * Clear all uses of the tracefile.
618 */
619 if (ops == KTROP_CLEARFILE) {
620 int vrele_count;
621
622 vrele_count = 0;
623 sx_slock(&allproc_lock);
624 FOREACH_PROC_IN_SYSTEM(p) {
625 PROC_LOCK(p);
626 if (p->p_tracevp == vp) {
627 if (ktrcanset(td, p)) {
628 mtx_lock(&ktrace_mtx);
629 cred = p->p_tracecred;
630 p->p_tracecred = NULL;
631 p->p_tracevp = NULL;
632 p->p_traceflag = 0;
633 mtx_unlock(&ktrace_mtx);
634 vrele_count++;
635 crfree(cred);
636 } else
637 error = EPERM;
638 }
639 PROC_UNLOCK(p);
640 }
641 sx_sunlock(&allproc_lock);
642 if (vrele_count > 0) {
643 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
644 while (vrele_count-- > 0)
645 vrele(vp);
646 VFS_UNLOCK_GIANT(vfslocked);
647 }
648 goto done;
649 }
650 /*
651 * do it
652 */
653 sx_slock(&proctree_lock);
654 if (uap->pid < 0) {
655 /*
656 * by process group
657 */
658 pg = pgfind(-uap->pid);
659 if (pg == NULL) {
660 sx_sunlock(&proctree_lock);
661 error = ESRCH;
662 goto done;
663 }
664 /*
665 * ktrops() may call vrele(). Lock pg_members
666 * by the proctree_lock rather than pg_mtx.
667 */
668 PGRP_UNLOCK(pg);
669 nfound = 0;
670 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
671 PROC_LOCK(p);
672 if (p_cansee(td, p) != 0) {
673 PROC_UNLOCK(p);
674 continue;
675 }
676 PROC_UNLOCK(p);
677 nfound++;
678 if (descend)
679 ret |= ktrsetchildren(td, p, ops, facs, vp);
680 else
681 ret |= ktrops(td, p, ops, facs, vp);
682 }
683 if (nfound == 0) {
684 sx_sunlock(&proctree_lock);
685 error = ESRCH;
686 goto done;
687 }
688 } else {
689 /*
690 * by pid
691 */
692 p = pfind(uap->pid);
693 if (p == NULL) {
694 sx_sunlock(&proctree_lock);
695 error = ESRCH;
696 goto done;
697 }
698 error = p_cansee(td, p);
699 /*
700 * The slock of the proctree lock will keep this process
701 * from going away, so unlocking the proc here is ok.
702 */
703 PROC_UNLOCK(p);
704 if (error) {
705 sx_sunlock(&proctree_lock);
706 goto done;
707 }
708 if (descend)
709 ret |= ktrsetchildren(td, p, ops, facs, vp);
710 else
711 ret |= ktrops(td, p, ops, facs, vp);
712 }
713 sx_sunlock(&proctree_lock);
714 if (!ret)
715 error = EPERM;
716 done:
717 if (vp != NULL) {
718 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
719 (void) vn_close(vp, FWRITE, td->td_ucred, td);
720 VFS_UNLOCK_GIANT(vfslocked);
721 }
722 ktrace_exit(td);
723 return (error);
724 #else /* !KTRACE */
725 return (ENOSYS);
726 #endif /* KTRACE */
727 }
728
729 /* ARGSUSED */
730 int
731 utrace(td, uap)
732 struct thread *td;
733 register struct utrace_args *uap;
734 {
735
736 #ifdef KTRACE
737 struct ktr_request *req;
738 void *cp;
739 int error;
740
741 if (!KTRPOINT(td, KTR_USER))
742 return (0);
743 if (uap->len > KTR_USER_MAXLEN)
744 return (EINVAL);
745 cp = malloc(uap->len, M_KTRACE, M_WAITOK);
746 error = copyin(uap->addr, cp, uap->len);
747 if (error) {
748 free(cp, M_KTRACE);
749 return (error);
750 }
751 req = ktr_getrequest(KTR_USER);
752 if (req == NULL) {
753 free(cp, M_KTRACE);
754 return (ENOMEM);
755 }
756 req->ktr_buffer = cp;
757 req->ktr_header.ktr_len = uap->len;
758 ktr_submitrequest(td, req);
759 return (0);
760 #else /* !KTRACE */
761 return (ENOSYS);
762 #endif /* KTRACE */
763 }
764
765 #ifdef KTRACE
766 static int
767 ktrops(td, p, ops, facs, vp)
768 struct thread *td;
769 struct proc *p;
770 int ops, facs;
771 struct vnode *vp;
772 {
773 struct vnode *tracevp = NULL;
774 struct ucred *tracecred = NULL;
775
776 PROC_LOCK(p);
777 if (!ktrcanset(td, p)) {
778 PROC_UNLOCK(p);
779 return (0);
780 }
781 mtx_lock(&ktrace_mtx);
782 if (ops == KTROP_SET) {
783 if (p->p_tracevp != vp) {
784 /*
785 * if trace file already in use, relinquish below
786 */
787 tracevp = p->p_tracevp;
788 VREF(vp);
789 p->p_tracevp = vp;
790 }
791 if (p->p_tracecred != td->td_ucred) {
792 tracecred = p->p_tracecred;
793 p->p_tracecred = crhold(td->td_ucred);
794 }
795 p->p_traceflag |= facs;
796 if (priv_check(td, PRIV_KTRACE) == 0)
797 p->p_traceflag |= KTRFAC_ROOT;
798 } else {
799 /* KTROP_CLEAR */
800 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
801 /* no more tracing */
802 p->p_traceflag = 0;
803 tracevp = p->p_tracevp;
804 p->p_tracevp = NULL;
805 tracecred = p->p_tracecred;
806 p->p_tracecred = NULL;
807 }
808 }
809 mtx_unlock(&ktrace_mtx);
810 PROC_UNLOCK(p);
811 if (tracevp != NULL) {
812 int vfslocked;
813
814 vfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
815 vrele(tracevp);
816 VFS_UNLOCK_GIANT(vfslocked);
817 }
818 if (tracecred != NULL)
819 crfree(tracecred);
820
821 return (1);
822 }
823
824 static int
825 ktrsetchildren(td, top, ops, facs, vp)
826 struct thread *td;
827 struct proc *top;
828 int ops, facs;
829 struct vnode *vp;
830 {
831 register struct proc *p;
832 register int ret = 0;
833
834 p = top;
835 sx_assert(&proctree_lock, SX_LOCKED);
836 for (;;) {
837 ret |= ktrops(td, p, ops, facs, vp);
838 /*
839 * If this process has children, descend to them next,
840 * otherwise do any siblings, and if done with this level,
841 * follow back up the tree (but not past top).
842 */
843 if (!LIST_EMPTY(&p->p_children))
844 p = LIST_FIRST(&p->p_children);
845 else for (;;) {
846 if (p == top)
847 return (ret);
848 if (LIST_NEXT(p, p_sibling)) {
849 p = LIST_NEXT(p, p_sibling);
850 break;
851 }
852 p = p->p_pptr;
853 }
854 }
855 /*NOTREACHED*/
856 }
857
858 static void
859 ktr_writerequest(struct thread *td, struct ktr_request *req)
860 {
861 struct ktr_header *kth;
862 struct vnode *vp;
863 struct proc *p;
864 struct ucred *cred;
865 struct uio auio;
866 struct iovec aiov[3];
867 struct mount *mp;
868 int datalen, buflen, vrele_count;
869 int error, vfslocked;
870
871 /*
872 * We hold the vnode and credential for use in I/O in case ktrace is
873 * disabled on the process as we write out the request.
874 *
875 * XXXRW: This is not ideal: we could end up performing a write after
876 * the vnode has been closed.
877 */
878 mtx_lock(&ktrace_mtx);
879 vp = td->td_proc->p_tracevp;
880 if (vp != NULL)
881 VREF(vp);
882 cred = td->td_proc->p_tracecred;
883 if (cred != NULL)
884 crhold(cred);
885 mtx_unlock(&ktrace_mtx);
886
887 /*
888 * If vp is NULL, the vp has been cleared out from under this
889 * request, so just drop it. Make sure the credential and vnode are
890 * in sync: we should have both or neither.
891 */
892 if (vp == NULL) {
893 KASSERT(cred == NULL, ("ktr_writerequest: cred != NULL"));
894 return;
895 }
896 KASSERT(cred != NULL, ("ktr_writerequest: cred == NULL"));
897
898 kth = &req->ktr_header;
899 datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP];
900 buflen = kth->ktr_len;
901 auio.uio_iov = &aiov[0];
902 auio.uio_offset = 0;
903 auio.uio_segflg = UIO_SYSSPACE;
904 auio.uio_rw = UIO_WRITE;
905 aiov[0].iov_base = (caddr_t)kth;
906 aiov[0].iov_len = sizeof(struct ktr_header);
907 auio.uio_resid = sizeof(struct ktr_header);
908 auio.uio_iovcnt = 1;
909 auio.uio_td = td;
910 if (datalen != 0) {
911 aiov[1].iov_base = (caddr_t)&req->ktr_data;
912 aiov[1].iov_len = datalen;
913 auio.uio_resid += datalen;
914 auio.uio_iovcnt++;
915 kth->ktr_len += datalen;
916 }
917 if (buflen != 0) {
918 KASSERT(req->ktr_buffer != NULL, ("ktrace: nothing to write"));
919 aiov[auio.uio_iovcnt].iov_base = req->ktr_buffer;
920 aiov[auio.uio_iovcnt].iov_len = buflen;
921 auio.uio_resid += buflen;
922 auio.uio_iovcnt++;
923 }
924
925 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
926 vn_start_write(vp, &mp, V_WAIT);
927 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
928 (void)VOP_LEASE(vp, td, cred, LEASE_WRITE);
929 #ifdef MAC
930 error = mac_check_vnode_write(cred, NOCRED, vp);
931 if (error == 0)
932 #endif
933 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
934 VOP_UNLOCK(vp, 0, td);
935 vn_finished_write(mp);
936 vrele(vp);
937 VFS_UNLOCK_GIANT(vfslocked);
938 if (!error)
939 return;
940 /*
941 * If error encountered, give up tracing on this vnode. We defer
942 * all the vrele()'s on the vnode until after we are finished walking
943 * the various lists to avoid needlessly holding locks.
944 */
945 log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
946 error);
947 vrele_count = 0;
948 /*
949 * First, clear this vnode from being used by any processes in the
950 * system.
951 * XXX - If one process gets an EPERM writing to the vnode, should
952 * we really do this? Other processes might have suitable
953 * credentials for the operation.
954 */
955 cred = NULL;
956 sx_slock(&allproc_lock);
957 FOREACH_PROC_IN_SYSTEM(p) {
958 PROC_LOCK(p);
959 if (p->p_tracevp == vp) {
960 mtx_lock(&ktrace_mtx);
961 p->p_tracevp = NULL;
962 p->p_traceflag = 0;
963 cred = p->p_tracecred;
964 p->p_tracecred = NULL;
965 mtx_unlock(&ktrace_mtx);
966 vrele_count++;
967 }
968 PROC_UNLOCK(p);
969 if (cred != NULL) {
970 crfree(cred);
971 cred = NULL;
972 }
973 }
974 sx_sunlock(&allproc_lock);
975
976 /*
977 * We can't clear any pending requests in threads that have cached
978 * them but not yet committed them, as those are per-thread. The
979 * thread will have to clear it itself on system call return.
980 */
981 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
982 while (vrele_count-- > 0)
983 vrele(vp);
984 VFS_UNLOCK_GIANT(vfslocked);
985 }
986
987 /*
988 * Return true if caller has permission to set the ktracing state
989 * of target. Essentially, the target can't possess any
990 * more permissions than the caller. KTRFAC_ROOT signifies that
991 * root previously set the tracing status on the target process, and
992 * so, only root may further change it.
993 */
994 static int
995 ktrcanset(td, targetp)
996 struct thread *td;
997 struct proc *targetp;
998 {
999
1000 PROC_LOCK_ASSERT(targetp, MA_OWNED);
1001 if (targetp->p_traceflag & KTRFAC_ROOT &&
1002 priv_check(td, PRIV_KTRACE))
1003 return (0);
1004
1005 if (p_candebug(td, targetp) != 0)
1006 return (0);
1007
1008 return (1);
1009 }
1010
1011 #endif /* KTRACE */
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