1 /*
2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93
30 * $FreeBSD: src/sys/kern/kern_ktrace.c,v 1.35.2.6 2002/07/05 22:36:38 darrenr Exp $
31 */
32
33 #include "opt_ktrace.h"
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/uio.h>
38 #include <sys/sysmsg.h>
39 #include <sys/kernel.h>
40 #include <sys/proc.h>
41 #include <sys/fcntl.h>
42 #include <sys/lock.h>
43 #include <sys/nlookup.h>
44 #include <sys/vnode.h>
45 #include <sys/ktrace.h>
46 #include <sys/malloc.h>
47 #include <sys/sysctl.h>
48 #include <sys/syslog.h>
49 #include <sys/sysent.h>
50
51 #include <vm/vm_zone.h>
52
53 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
54
55 #ifdef KTRACE
56 static void ktrgetheader (struct ktr_header *kth, int type);
57 static struct ktr_syscall *ktrgetsyscall(struct ktr_header *kth,
58 struct ktr_syscall *ktp_cache, int narg);
59 static void ktrputsyscall(struct ktr_syscall *ktp_cache,
60 struct ktr_syscall *ktp);
61 static void ktrwrite (struct lwp *, struct ktr_header *, struct uio *);
62 static int ktrcanset (struct thread *,struct proc *);
63 static int ktrsetchildren (struct thread *, struct proc *,
64 int, int, ktrace_node_t);
65 static int ktrops (struct thread *,struct proc *,int,int, ktrace_node_t);
66
67 /*
68 * MPSAFE
69 */
70 static
71 void
ktrgetheader(struct ktr_header * kth,int type)72 ktrgetheader(struct ktr_header *kth, int type)
73 {
74 thread_t td = curthread;
75 struct proc *p = td->td_proc;
76 struct lwp *lp = td->td_lwp;
77
78 kth->ktr_type = type;
79 /* XXX threaded flag is a hack at the moment */
80 kth->ktr_flags = (p->p_nthreads > 1) ? KTRH_THREADED : 0;
81 kth->ktr_flags |= KTRH_CPUID_ENCODE(td->td_gd->gd_cpuid);
82 /*microtime(&kth->ktr_time); set in ktrwrite */
83 kth->ktr_pid = p->p_pid;
84 kth->ktr_tid = lp->lwp_tid;
85 bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1);
86 }
87
88 static
89 struct ktr_syscall *
ktrgetsyscall(struct ktr_header * kth,struct ktr_syscall * ktp_cache,int narg)90 ktrgetsyscall(struct ktr_header *kth, struct ktr_syscall *ktp_cache, int narg)
91 {
92 size_t len;
93
94 len = offsetof(struct ktr_syscall, ktr_args[narg]);
95 if (len > sizeof(*ktp_cache))
96 ktp_cache = kmalloc(len, M_KTRACE, M_WAITOK);
97 kth->ktr_buf = (caddr_t)ktp_cache;
98 kth->ktr_len = (int)len;
99 return (ktp_cache);
100 }
101
102 static
103 void
ktrputsyscall(struct ktr_syscall * ktp_cache,struct ktr_syscall * ktp)104 ktrputsyscall(struct ktr_syscall *ktp_cache, struct ktr_syscall *ktp)
105 {
106 if (ktp != ktp_cache)
107 kfree(ktp, M_KTRACE);
108 }
109
110 void
ktrsyscall(struct lwp * lp,int code,int narg,union sysunion * uap)111 ktrsyscall(struct lwp *lp, int code, int narg, union sysunion *uap)
112 {
113 struct ktr_header kth;
114 struct ktr_syscall ktp_cache;
115 struct ktr_syscall *ktp;
116 register_t *argp;
117 register_t *args = (void *)uap;
118 int i;
119
120 /*
121 * Setting the active bit prevents a ktrace recursion from the
122 * ktracing op itself.
123 */
124 lp->lwp_traceflag |= KTRFAC_ACTIVE;
125 ktrgetheader(&kth, KTR_SYSCALL);
126
127 ktp = ktrgetsyscall(&kth, &ktp_cache, narg);
128 ktp->ktr_code = code;
129 ktp->ktr_narg = narg;
130 argp = &ktp->ktr_args[0];
131 for (i = 0; i < narg; i++)
132 *argp++ = args[i];
133 ktrwrite(lp, &kth, NULL);
134
135 ktrputsyscall(&ktp_cache, ktp);
136 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
137 }
138
139 void
ktrsysret(struct lwp * lp,int code,int error,register_t retval)140 ktrsysret(struct lwp *lp, int code, int error, register_t retval)
141 {
142 struct ktr_header kth;
143 struct ktr_sysret ktp;
144
145 lp->lwp_traceflag |= KTRFAC_ACTIVE;
146 ktrgetheader(&kth, KTR_SYSRET);
147
148 ktp.ktr_code = code;
149 ktp.ktr_error = error;
150 if (error == 0)
151 ktp.ktr_retval = retval; /* what about val2 ? */
152 else
153 ktp.ktr_retval = 0;
154
155 kth.ktr_buf = (caddr_t)&ktp;
156 kth.ktr_len = (int)sizeof(struct ktr_sysret);
157
158 ktrwrite(lp, &kth, NULL);
159 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
160 }
161
162 void
ktrnamei(struct lwp * lp,char * path)163 ktrnamei(struct lwp *lp, char *path)
164 {
165 struct ktr_header kth;
166
167 lp->lwp_traceflag |= KTRFAC_ACTIVE;
168 ktrgetheader(&kth, KTR_NAMEI);
169
170 kth.ktr_len = (int)strlen(path);
171 kth.ktr_buf = path;
172
173 ktrwrite(lp, &kth, NULL);
174 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
175 }
176
177 void
ktrsysctl(struct lwp * lp,int * name,u_int namelen)178 ktrsysctl(struct lwp *lp, int *name, u_int namelen)
179 {
180 struct ktr_header kth;
181 u_int mib[CTL_MAXNAME + 2];
182 char *mibname;
183 size_t mibnamelen;
184 int error;
185
186 lp->lwp_traceflag |= KTRFAC_ACTIVE;
187 /* Lookup name of mib. */
188 KASSERT(namelen <= CTL_MAXNAME, ("sysctl MIB too long"));
189 mib[0] = 0;
190 mib[1] = 1;
191 bcopy(name, mib + 2, namelen * sizeof(*name));
192 mibnamelen = 128;
193 mibname = kmalloc(mibnamelen, M_KTRACE, M_WAITOK);
194 error = kernel_sysctl(mib, namelen + 2, mibname, &mibnamelen,
195 NULL, 0, &mibnamelen);
196 if (error) {
197 kfree(mibname, M_KTRACE);
198 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
199 return;
200 }
201 ktrgetheader(&kth, KTR_SYSCTL);
202 kth.ktr_len = mibnamelen;
203 kth.ktr_buf = mibname;
204 ktrwrite(lp, &kth, NULL);
205 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
206 }
207
208 void
ktrgenio(struct lwp * lp,int fd,enum uio_rw rw,struct uio * uio,int error)209 ktrgenio(struct lwp *lp, int fd, enum uio_rw rw, struct uio *uio, int error)
210 {
211 struct ktr_header kth;
212 struct ktr_genio ktg;
213
214 if (error)
215 return;
216 lp->lwp_traceflag |= KTRFAC_ACTIVE;
217 ktrgetheader(&kth, KTR_GENIO);
218
219 ktg.ktr_fd = fd;
220 ktg.ktr_rw = rw;
221 kth.ktr_buf = (caddr_t)&ktg;
222 kth.ktr_len = (int)sizeof(struct ktr_genio);
223 uio->uio_offset = 0;
224 uio->uio_rw = UIO_WRITE;
225
226 ktrwrite(lp, &kth, uio);
227 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
228 }
229
230 void
ktrpsig(struct lwp * lp,int sig,sig_t action,sigset_t * mask,int code)231 ktrpsig(struct lwp *lp, int sig, sig_t action, sigset_t *mask, int code)
232 {
233 struct ktr_header kth;
234 struct ktr_psig kp;
235
236 lp->lwp_traceflag |= KTRFAC_ACTIVE;
237 ktrgetheader(&kth, KTR_PSIG);
238
239 kp.signo = (char)sig;
240 kp.action = action;
241 kp.mask = *mask;
242 kp.code = code;
243 kth.ktr_buf = (caddr_t)&kp;
244 kth.ktr_len = (int)sizeof(struct ktr_psig);
245
246 ktrwrite(lp, &kth, NULL);
247 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
248 }
249
250 void
ktrcsw(struct lwp * lp,int out,int user)251 ktrcsw(struct lwp *lp, int out, int user)
252 {
253 struct ktr_header kth;
254 struct ktr_csw kc;
255
256 lp->lwp_traceflag |= KTRFAC_ACTIVE;
257 ktrgetheader(&kth, KTR_CSW);
258
259 kc.out = out;
260 kc.user = user;
261 kth.ktr_buf = (caddr_t)&kc;
262 kth.ktr_len = (int)sizeof(struct ktr_csw);
263
264 ktrwrite(lp, &kth, NULL);
265 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
266 }
267 #endif
268
269 /* Interface and common routines */
270
271 #ifdef KTRACE
272 /*
273 * ktrace system call
274 */
275 struct ktrace_clear_info {
276 ktrace_node_t tracenode;
277 int rootclear;
278 int error;
279 };
280
281 static int ktrace_clear_callback(struct proc *p, void *data);
282
283 #endif
284
285 /*
286 * MPALMOSTSAFE
287 */
288 int
sys_ktrace(struct sysmsg * sysmsg,const struct ktrace_args * uap)289 sys_ktrace(struct sysmsg *sysmsg, const struct ktrace_args *uap)
290 {
291 #ifdef KTRACE
292 struct ktrace_clear_info info;
293 struct thread *td = curthread;
294 struct proc *curp = td->td_proc;
295 struct proc *p;
296 struct pgrp *pg;
297 int facs = uap->facs & ~KTRFAC_ROOT;
298 int ops = KTROP(uap->ops);
299 int descend = uap->ops & KTRFLAG_DESCEND;
300 int ret = 0;
301 int error = 0;
302 struct nlookupdata nd;
303 ktrace_node_t tracenode = NULL;
304
305 lwkt_gettoken(&curp->p_token);
306 curp->p_traceflag |= KTRFAC_ACTIVE;
307
308 if (ops != KTROP_CLEAR) {
309 /*
310 * an operation which requires a file argument.
311 */
312 error = nlookup_init(&nd, uap->fname,
313 UIO_USERSPACE, NLC_LOCKVP);
314 if (error == 0)
315 error = vn_open(&nd, NULL, FREAD|FWRITE|O_NOFOLLOW, 0);
316 if (error == 0 && nd.nl_open_vp->v_type != VREG)
317 error = EACCES;
318 if (error) {
319 curp->p_traceflag &= ~KTRFAC_ACTIVE;
320 nlookup_done(&nd);
321 goto done;
322 }
323 tracenode = kmalloc(sizeof(struct ktrace_node), M_KTRACE,
324 M_WAITOK | M_ZERO);
325 tracenode->kn_vp = nd.nl_open_vp;
326 tracenode->kn_refs = 1;
327 nd.nl_open_vp = NULL;
328 nlookup_done(&nd);
329 vn_unlock(tracenode->kn_vp);
330 }
331 /*
332 * Clear all uses of the tracefile. Not the most efficient operation
333 * in the world.
334 */
335 if (ops == KTROP_CLEARFILE) {
336 info.tracenode = tracenode;
337 info.error = 0;
338 info.rootclear = 0;
339 allproc_scan(ktrace_clear_callback, &info, 0);
340 error = info.error;
341 goto done;
342 }
343 /*
344 * need something to (un)trace (XXX - why is this here?)
345 */
346 if (!facs) {
347 error = EINVAL;
348 goto done;
349 }
350 /*
351 * do it
352 */
353 if (uap->pid < 0) {
354 /*
355 * By process group. Process group is referenced, preventing
356 * disposal.
357 */
358 pg = pgfind(-uap->pid);
359 if (pg == NULL) {
360 error = ESRCH;
361 goto done;
362 }
363 lwkt_gettoken(&pg->pg_token);
364 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
365 PHOLD(p);
366 if (descend)
367 ret |= ktrsetchildren(td, p, ops, facs, tracenode);
368 else
369 ret |= ktrops(td, p, ops, facs, tracenode);
370 PRELE(p);
371 }
372 lwkt_reltoken(&pg->pg_token);
373 pgrel(pg);
374 } else {
375 /*
376 * by pid
377 */
378 p = pfind(uap->pid);
379 if (p == NULL) {
380 error = ESRCH;
381 goto done;
382 }
383 if (descend)
384 ret |= ktrsetchildren(td, p, ops, facs, tracenode);
385 else
386 ret |= ktrops(td, p, ops, facs, tracenode);
387 PRELE(p);
388 }
389 if (!ret)
390 error = EPERM;
391 done:
392 if (tracenode)
393 ktrdestroy(&tracenode);
394 curp->p_traceflag &= ~KTRFAC_ACTIVE;
395 lwkt_reltoken(&curp->p_token);
396 return (error);
397 #else
398 return ENOSYS;
399 #endif
400 }
401
402 #ifdef KTRACE
403
404 /*
405 * NOTE: NOT MPSAFE (yet)
406 */
407 static int
ktrace_clear_callback(struct proc * p,void * data)408 ktrace_clear_callback(struct proc *p, void *data)
409 {
410 struct ktrace_clear_info *info = data;
411
412 if (p->p_tracenode) {
413 if (info->rootclear) {
414 if (p->p_tracenode == info->tracenode) {
415 ktrdestroy(&p->p_tracenode);
416 p->p_traceflag = 0;
417 }
418 } else {
419 if (p->p_tracenode->kn_vp == info->tracenode->kn_vp) {
420 if (ktrcanset(curthread, p)) {
421 ktrdestroy(&p->p_tracenode);
422 p->p_traceflag = 0;
423 } else {
424 info->error = EPERM;
425 }
426 }
427 }
428 }
429 return(0);
430 }
431
432 #endif
433
434 /*
435 * utrace system call
436 *
437 * MPALMOSTSAFE
438 */
439 int
sys_utrace(struct sysmsg * sysmsg,const struct utrace_args * uap)440 sys_utrace(struct sysmsg *sysmsg, const struct utrace_args *uap)
441 {
442 #ifdef KTRACE
443 struct ktr_header kth;
444 struct thread *td = curthread; /* XXX */
445 char cp_cache[64];
446 caddr_t cp;
447
448 if (!KTRPOINT(td, KTR_USER))
449 return (0);
450 if (uap->len > KTR_USER_MAXLEN)
451 return (EINVAL);
452 td->td_lwp->lwp_traceflag |= KTRFAC_ACTIVE;
453 ktrgetheader(&kth, KTR_USER);
454 if (uap->len <= sizeof(cp_cache))
455 cp = cp_cache;
456 else
457 cp = kmalloc(uap->len, M_KTRACE, M_WAITOK);
458
459 if (!copyin(uap->addr, cp, uap->len)) {
460 kth.ktr_buf = cp;
461 kth.ktr_len = uap->len;
462 ktrwrite(td->td_lwp, &kth, NULL);
463 }
464 if (cp != cp_cache)
465 kfree(cp, M_KTRACE);
466 td->td_lwp->lwp_traceflag &= ~KTRFAC_ACTIVE;
467
468 return (0);
469 #else
470 return (ENOSYS);
471 #endif
472 }
473
474 void
ktrdestroy(struct ktrace_node ** tracenodep)475 ktrdestroy(struct ktrace_node **tracenodep)
476 {
477 ktrace_node_t tracenode;
478
479 if ((tracenode = *tracenodep) != NULL) {
480 *tracenodep = NULL;
481 KKASSERT(tracenode->kn_refs > 0);
482 if (atomic_fetchadd_int(&tracenode->kn_refs, -1) == 1) {
483 vn_close(tracenode->kn_vp, FREAD|FWRITE, NULL);
484 tracenode->kn_vp = NULL;
485 kfree(tracenode, M_KTRACE);
486 }
487 }
488 }
489
490 /*
491 * This allows a process to inherit a ref on a tracenode and is also used
492 * as a temporary ref to prevent a tracenode from being destroyed out from
493 * under an active operation.
494 */
495 ktrace_node_t
ktrinherit(ktrace_node_t tracenode)496 ktrinherit(ktrace_node_t tracenode)
497 {
498 if (tracenode) {
499 KKASSERT(tracenode->kn_refs > 0);
500 atomic_add_int(&tracenode->kn_refs, 1);
501 }
502 return(tracenode);
503 }
504
505 #ifdef KTRACE
506 static int
ktrops(struct thread * td,struct proc * p,int ops,int facs,ktrace_node_t tracenode)507 ktrops(struct thread *td, struct proc *p, int ops, int facs,
508 ktrace_node_t tracenode)
509 {
510 ktrace_node_t oldnode;
511
512 if (!ktrcanset(td, p))
513 return (0);
514 if (ops == KTROP_SET) {
515 if ((oldnode = p->p_tracenode) != tracenode) {
516 p->p_tracenode = ktrinherit(tracenode);
517 ktrdestroy(&oldnode);
518 }
519 p->p_traceflag |= facs;
520 if (td->td_ucred->cr_uid == 0)
521 p->p_traceflag |= KTRFAC_ROOT;
522 } else {
523 /* KTROP_CLEAR */
524 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
525 /* no more tracing */
526 p->p_traceflag = 0;
527 ktrdestroy(&p->p_tracenode);
528 }
529 }
530
531 return (1);
532 }
533
534 static int
ktrsetchildren(struct thread * td,struct proc * top,int ops,int facs,ktrace_node_t tracenode)535 ktrsetchildren(struct thread *td, struct proc *top, int ops, int facs,
536 ktrace_node_t tracenode)
537 {
538 struct proc *p;
539 struct proc *np;
540 int ret = 0;
541
542 p = top;
543 PHOLD(p);
544 lwkt_gettoken(&p->p_token);
545
546 for (;;) {
547 ret |= ktrops(td, p, ops, facs, tracenode);
548
549 /*
550 * If this process has children, descend to them next,
551 * otherwise do any siblings, and if done with this level,
552 * follow back up the tree (but not past top).
553 */
554 if ((np = LIST_FIRST(&p->p_children)) != NULL) {
555 PHOLD(np);
556 }
557 while (np == NULL) {
558 if (p == top)
559 break;
560 if ((np = LIST_NEXT(p, p_sibling)) != NULL) {
561 PHOLD(np);
562 break;
563 }
564
565 /*
566 * recurse up to parent, set p in our inner
567 * loop when doing this. np can be NULL if
568 * we race a reparenting to init (thus 'top'
569 * is skipped past and never encountered).
570 */
571 np = p->p_pptr;
572 if (np == NULL)
573 break;
574 PHOLD(np);
575 lwkt_reltoken(&p->p_token);
576 PRELE(p);
577 p = np;
578 lwkt_gettoken(&p->p_token);
579 np = NULL;
580 }
581 lwkt_reltoken(&p->p_token);
582 PRELE(p);
583 p = np;
584 if (p == NULL)
585 break;
586 /* Already held, but we need the token too */
587 lwkt_gettoken(&p->p_token);
588 }
589 return (ret);
590 }
591
592 static void
ktrwrite(struct lwp * lp,struct ktr_header * kth,struct uio * uio)593 ktrwrite(struct lwp *lp, struct ktr_header *kth, struct uio *uio)
594 {
595 struct ktrace_clear_info info;
596 struct uio auio;
597 struct iovec aiov[2];
598 int error;
599 ktrace_node_t tracenode;
600
601 /*
602 * We have to ref our tracenode to prevent it from being ripped out
603 * from under us while we are trying to use it. p_tracenode can
604 * go away at any time if another process gets a write error.
605 *
606 * XXX not MP safe
607 */
608 if (lp->lwp_proc->p_tracenode == NULL)
609 return;
610 tracenode = ktrinherit(lp->lwp_proc->p_tracenode);
611 auio.uio_iov = &aiov[0];
612 auio.uio_offset = 0;
613 auio.uio_segflg = UIO_SYSSPACE;
614 auio.uio_rw = UIO_WRITE;
615 aiov[0].iov_base = (caddr_t)kth;
616 aiov[0].iov_len = sizeof(struct ktr_header);
617 auio.uio_resid = sizeof(struct ktr_header);
618 auio.uio_iovcnt = 1;
619 auio.uio_td = curthread;
620 if (kth->ktr_len > 0) {
621 auio.uio_iovcnt++;
622 aiov[1].iov_base = kth->ktr_buf;
623 aiov[1].iov_len = kth->ktr_len;
624 auio.uio_resid += kth->ktr_len;
625 if (uio != NULL)
626 kth->ktr_len += uio->uio_resid;
627 }
628
629 /*
630 * NOTE: Must set timestamp after obtaining lock to ensure no
631 * timestamp reversals in the output file.
632 */
633 vn_lock(tracenode->kn_vp, LK_EXCLUSIVE | LK_RETRY);
634 microtime(&kth->ktr_time);
635 error = VOP_WRITE(tracenode->kn_vp, &auio,
636 IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
637 if (error == 0 && uio != NULL) {
638 error = VOP_WRITE(tracenode->kn_vp, uio,
639 IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
640 }
641 vn_unlock(tracenode->kn_vp);
642 if (error) {
643 /*
644 * If an error occured, give up tracing on all processes
645 * using this tracenode. This is not MP safe but is
646 * blocking-safe.
647 */
648 log(LOG_NOTICE,
649 "ktrace write failed, errno %d, tracing stopped\n", error);
650 info.tracenode = tracenode;
651 info.error = 0;
652 info.rootclear = 1;
653 allproc_scan(ktrace_clear_callback, &info, 0);
654 }
655 ktrdestroy(&tracenode);
656 }
657
658 /*
659 * Return true if caller has permission to set the ktracing state
660 * of target. Essentially, the target can't possess any
661 * more permissions than the caller. KTRFAC_ROOT signifies that
662 * root previously set the tracing status on the target process, and
663 * so, only root may further change it.
664 *
665 * TODO: check groups. use caller effective gid.
666 */
667 static int
ktrcanset(struct thread * calltd,struct proc * targetp)668 ktrcanset(struct thread *calltd, struct proc *targetp)
669 {
670 struct ucred *caller = calltd->td_ucred;
671 struct ucred *target = targetp->p_ucred;
672
673 if (!PRISON_CHECK(caller, target))
674 return (0);
675 if ((caller->cr_uid == target->cr_ruid &&
676 target->cr_ruid == target->cr_svuid &&
677 caller->cr_rgid == target->cr_rgid && /* XXX */
678 target->cr_rgid == target->cr_svgid &&
679 (targetp->p_traceflag & KTRFAC_ROOT) == 0 &&
680 (targetp->p_flags & P_SUGID) == 0) ||
681 caller->cr_uid == 0)
682 return (1);
683
684 return (0);
685 }
686
687 #endif /* KTRACE */
688