1 /*
2 * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
29 /*-
30 * Copyright (c) 1982, 1986, 1989, 1993
31 * The Regents of the University of California. All rights reserved.
32 * (c) UNIX System Laboratories, Inc.
33 * All or some portions of this file are derived from material licensed
34 * to the University of California by American Telephone and Telegraph
35 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
36 * the permission of UNIX System Laboratories, Inc.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. All advertising materials mentioning features or use of this software
47 * must display the following acknowledgement:
48 * This product includes software developed by the University of
49 * California, Berkeley and its contributors.
50 * 4. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
53 *
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
65 *
66 * from: @(#)sys_process.c 8.1 (Berkeley) 6/10/93
67 */
68
69 #include <machine/reg.h>
70 #include <machine/psl.h>
71
72 #include <sys/param.h>
73 #include <sys/systm.h>
74 #include <sys/proc_internal.h>
75 #include <sys/kauth.h>
76 #include <sys/errno.h>
77 #include <sys/ptrace.h>
78 #include <sys/uio.h>
79 #include <sys/user.h>
80 #include <sys/sysctl.h>
81 #include <sys/wait.h>
82
83 #include <sys/mount_internal.h>
84 #include <sys/sysproto.h>
85 #include <sys/kdebug.h>
86 #include <sys/codesign.h> /* cs_allow_invalid() */
87
88 #include <security/audit/audit.h>
89
90 #include <kern/task.h>
91 #include <kern/thread.h>
92
93 #include <mach/task.h> /* for task_resume() */
94 #include <kern/sched_prim.h> /* for thread_exception_return() */
95
96 #include <pexpert/pexpert.h>
97
98 #if CONFIG_MACF
99 #include <security/mac_framework.h>
100 #endif
101
102 /* XXX ken/bsd_kern.c - prototype should be in common header */
103 int get_task_userstop(task_t);
104
105 /* Macros to clear/set/test flags. */
106 #define SET(t, f) (t) |= (f)
107 #define CLR(t, f) (t) &= ~(f)
108 #define ISSET(t, f) ((t) & (f))
109
110 extern thread_t get_firstthread(task_t);
111
112
113 /*
114 * sys-trace system call.
115 */
116
117 int
ptrace(struct proc * p,struct ptrace_args * uap,int32_t * retval)118 ptrace(struct proc *p, struct ptrace_args *uap, int32_t *retval)
119 {
120 struct proc *t; /* target process */
121 struct proc_ident tident; /* target ident */
122 task_t task;
123 thread_t th_act = THREAD_NULL;
124 struct uthread *ut;
125 int tr_sigexc = 0;
126 int error = 0;
127 int stopped = 0;
128
129 AUDIT_ARG(cmd, uap->req);
130 AUDIT_ARG(pid, uap->pid);
131 AUDIT_ARG(addr, uap->addr);
132 AUDIT_ARG(value32, uap->data);
133
134 if (uap->req == PT_DENY_ATTACH) {
135 #if (DEVELOPMENT || DEBUG) && !defined(XNU_TARGET_OS_OSX)
136 if (PE_i_can_has_debugger(NULL)) {
137 return 0;
138 }
139 #endif
140 proc_lock(p);
141 if (ISSET(p->p_lflag, P_LTRACED)) {
142 proc_unlock(p);
143 KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
144 proc_getpid(p), W_EXITCODE(ENOTSUP, 0), 4, 0, 0);
145 exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
146
147 thread_exception_return();
148 /* NOTREACHED */
149 }
150 SET(p->p_lflag, P_LNOATTACH);
151 proc_unlock(p);
152
153 return 0;
154 }
155
156 if (uap->req == PT_FORCEQUOTA) {
157 if (kauth_cred_issuser(kauth_cred_get())) {
158 t = current_proc();
159 OSBitOrAtomic(P_FORCEQUOTA, &t->p_flag);
160 return 0;
161 } else {
162 return EPERM;
163 }
164 }
165
166 /*
167 * Intercept and deal with "please trace me" request.
168 */
169 if (uap->req == PT_TRACE_ME) {
170 retry_trace_me: ;
171 proc_t pproc = proc_parent(p);
172 if (pproc == NULL) {
173 return EINVAL;
174 }
175 /* holding ref on pproc */
176
177 #if CONFIG_MACF
178 /*
179 * NB: Cannot call kauth_authorize_process(..., KAUTH_PROCESS_CANTRACE, ...)
180 * since that assumes the process being checked is the current process
181 * when, in this case, it is the current process's parent.
182 * Most of the other checks in cantrace() don't apply either.
183 */
184 struct proc_ident p_ident = proc_ident_with_policy(p, IDENT_VALIDATION_PROC_EXACT);
185 struct proc_ident pproc_ident = proc_ident_with_policy(pproc, IDENT_VALIDATION_PROC_EXACT);
186 kauth_cred_t pproc_cred = kauth_cred_proc_ref(pproc);
187
188 /* Release pproc and find it again after MAC call to avoid deadlock */
189 proc_rele(pproc);
190 error = mac_proc_check_debug(&pproc_ident, pproc_cred, &p_ident);
191 kauth_cred_unref(&pproc_cred);
192
193 if (error != 0) {
194 return error;
195 }
196 if (proc_find_ident(&pproc_ident) == PROC_NULL) {
197 return ESRCH;
198 }
199 /* re-holding ref on pproc */
200 #endif
201 proc_lock(p);
202 /* Make sure the process wasn't re-parented. */
203 if (p->p_ppid != proc_getpid(pproc)) {
204 proc_unlock(p);
205 proc_rele(pproc); /* pproc ref released */
206 goto retry_trace_me;
207 }
208 SET(p->p_lflag, P_LTRACED);
209 /* Non-attached case, our tracer is our parent. */
210 p->p_oppid = p->p_ppid;
211 proc_unlock(p);
212 /* Child and parent will have to be able to run modified code. */
213 cs_allow_invalid(p);
214 cs_allow_invalid(pproc);
215 proc_rele(pproc); /* pproc ref released */
216
217 return error;
218 }
219 if (uap->req == PT_SIGEXC) {
220 proc_lock(p);
221 if (ISSET(p->p_lflag, P_LTRACED)) {
222 SET(p->p_lflag, P_LSIGEXC);
223 proc_unlock(p);
224 return 0;
225 } else {
226 proc_unlock(p);
227 return EINVAL;
228 }
229 }
230
231 /*
232 * We do not want ptrace to do anything with kernel or launchd
233 */
234 if (uap->pid < 2) {
235 return EPERM;
236 }
237
238 retry_proc_find:
239 /*
240 * Locate victim, and make sure it is traceable.
241 */
242 if ((t = proc_find(uap->pid)) == NULL) {
243 return ESRCH;
244 }
245
246 /* Check if the proc has trace wait flag set */
247 if (t->p_lflag & P_LTRACE_WAIT) {
248 proc_rele(t);
249 delay(1);
250 goto retry_proc_find;
251 }
252
253 AUDIT_ARG(process, t);
254
255 task = proc_task(t);
256 tident = proc_ident_with_policy(t, IDENT_VALIDATION_PROC_EXACT);
257 if (uap->req == PT_ATTACHEXC) {
258 #pragma clang diagnostic push
259 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
260 uap->req = PT_ATTACH;
261 tr_sigexc = 1;
262 }
263 if (uap->req == PT_ATTACH) {
264 #pragma clang diagnostic pop
265 int err, cb_err;
266
267 #if !defined(XNU_TARGET_OS_OSX)
268 if (tr_sigexc == 0) {
269 error = ENOTSUP;
270 goto out;
271 }
272 #endif
273
274 err = kauth_authorize_process(kauth_cred_get(), KAUTH_PROCESS_CANTRACE,
275 t, (uintptr_t)&cb_err, 0, 0);
276
277 if (err == 0) {
278 /* it's OK to attach */
279 proc_lock(t);
280 SET(t->p_lflag, P_LTRACED);
281 if (tr_sigexc) {
282 SET(t->p_lflag, P_LSIGEXC);
283 }
284
285 t->p_oppid = t->p_ppid;
286 /* Check whether child and parent are allowed to run modified
287 * code (they'll have to) */
288 proc_unlock(t);
289 cs_allow_invalid(t);
290 cs_allow_invalid(p);
291 if (t->p_pptr != p) {
292 proc_reparentlocked(t, p, 1, 0);
293 }
294
295 proc_lock(t);
296 if (get_task_userstop(task) > 0) {
297 stopped = 1;
298 }
299 t->p_xstat = 0;
300 proc_unlock(t);
301 psignal(t, SIGSTOP);
302 /*
303 * If the process was stopped, wake up and run through
304 * issignal() again to properly connect to the tracing
305 * process.
306 */
307 if (stopped) {
308 task_resume(task);
309 }
310 error = 0;
311 goto out;
312 } else {
313 error = cb_err;
314 if (error == ESRCH) {
315 /*
316 * The target 't' is not valid anymore as it
317 * could not be found after the MAC check.
318 */
319 return error;
320 }
321 /* not allowed to attach, proper error code returned by kauth_authorize_process */
322 if (ISSET(t->p_lflag, P_LNOATTACH)) {
323 psignal(p, SIGSEGV);
324 }
325 goto out;
326 }
327 }
328
329 /*
330 * You can't do what you want to the process if:
331 * (1) It's not being traced at all,
332 */
333 proc_lock(t);
334 if (!ISSET(t->p_lflag, P_LTRACED)) {
335 proc_unlock(t);
336 error = EPERM;
337 goto out;
338 }
339
340 /*
341 * (2) it's not being traced by _you_, or
342 */
343 if (t->p_pptr != p) {
344 proc_unlock(t);
345 error = EBUSY;
346 goto out;
347 }
348
349 /*
350 * (3) it's not currently stopped.
351 */
352 if (t->p_stat != SSTOP) {
353 proc_unlock(t);
354 error = EBUSY;
355 goto out;
356 }
357
358 /*
359 * Mach version of ptrace executes request directly here,
360 * thus simplifying the interaction of ptrace and signals.
361 */
362 /* proc lock is held here */
363 switch (uap->req) {
364 case PT_DETACH:
365 if (t->p_oppid != t->p_ppid) {
366 struct proc *pp;
367
368 proc_unlock(t);
369 pp = proc_find(t->p_oppid);
370 if (pp != PROC_NULL) {
371 proc_reparentlocked(t, pp, 1, 0);
372 proc_rele(pp);
373 } else {
374 /* original parent exited while traced */
375 proc_list_lock();
376 t->p_listflag |= P_LIST_DEADPARENT;
377 proc_list_unlock();
378 proc_reparentlocked(t, initproc, 1, 0);
379 }
380 proc_lock(t);
381 }
382
383 t->p_oppid = 0;
384 CLR(t->p_lflag, P_LTRACED);
385 CLR(t->p_lflag, P_LSIGEXC);
386 proc_unlock(t);
387 goto resume;
388
389 case PT_KILL:
390 /*
391 * Tell child process to kill itself after it
392 * is resumed by adding NSIG to p_cursig. [see issig]
393 */
394 proc_unlock(t);
395 #if CONFIG_MACF
396 error = mac_proc_check_signal(p, NULL, &tident, SIGKILL);
397 if (0 != error) {
398 goto resume;
399 }
400 #endif
401 psignal(t, SIGKILL);
402 goto resume;
403
404 case PT_STEP: /* single step the child */
405 case PT_CONTINUE: /* continue the child */
406 proc_unlock(t);
407 th_act = (thread_t)get_firstthread(task);
408 if (th_act == THREAD_NULL) {
409 error = EINVAL;
410 goto out;
411 }
412
413 /* force use of Mach SPIs (and task_for_pid security checks) to adjust PC */
414 if (uap->addr != (user_addr_t)1) {
415 error = ENOTSUP;
416 goto out;
417 }
418
419 if ((unsigned)uap->data >= NSIG) {
420 error = EINVAL;
421 goto out;
422 }
423
424 if (uap->data != 0) {
425 #if CONFIG_MACF
426 error = mac_proc_check_signal(p, NULL, &tident, uap->data);
427 if (0 != error) {
428 goto out;
429 }
430 #endif
431 psignal(t, uap->data);
432 }
433
434 if (uap->req == PT_STEP) {
435 /*
436 * set trace bit
437 * we use sending SIGSTOP as a comparable security check.
438 */
439 #if CONFIG_MACF
440 error = mac_proc_check_signal(p, NULL, &tident, SIGSTOP);
441 if (0 != error) {
442 goto out;
443 }
444 #endif
445 if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
446 error = ENOTSUP;
447 goto out;
448 }
449 } else {
450 /*
451 * clear trace bit if on
452 * we use sending SIGCONT as a comparable security check.
453 */
454 #if CONFIG_MACF
455 error = mac_proc_check_signal(p, NULL, &tident, SIGCONT);
456 if (0 != error) {
457 goto out;
458 }
459 #endif
460 if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
461 error = ENOTSUP;
462 goto out;
463 }
464 }
465 resume:
466 proc_lock(t);
467 t->p_xstat = uap->data;
468 t->p_stat = SRUN;
469 if (t->sigwait) {
470 wakeup((caddr_t)&(t->sigwait));
471 proc_unlock(t);
472 if ((t->p_lflag & P_LSIGEXC) == 0) {
473 task_resume(task);
474 }
475 } else {
476 proc_unlock(t);
477 }
478
479 break;
480
481 case PT_THUPDATE: {
482 proc_unlock(t);
483 if ((unsigned)uap->data >= NSIG) {
484 error = EINVAL;
485 goto out;
486 }
487 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr),
488 PORT_INTRANS_OPTIONS_NONE);
489 if (th_act == THREAD_NULL) {
490 error = ESRCH;
491 goto out;
492 }
493 ut = (uthread_t)get_bsdthread_info(th_act);
494 if (uap->data) {
495 ut->uu_siglist |= sigmask(uap->data);
496 }
497 proc_lock(t);
498 t->p_xstat = uap->data;
499 t->p_stat = SRUN;
500 proc_unlock(t);
501 error = 0;
502 }
503 break;
504 default:
505 proc_unlock(t);
506 error = EINVAL;
507 goto out;
508 }
509
510 error = 0;
511 out:
512 proc_rele(t);
513 if (th_act) {
514 thread_deallocate(th_act);
515 }
516 return error;
517 }
518
519
520 /*
521 * determine if one process (cur_procp) can trace another process (traced_procp).
522 */
523
524 int
cantrace(proc_t cur_procp,kauth_cred_t creds,proc_t traced_procp,int * errp)525 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
526 {
527 int my_err;
528 /*
529 * You can't trace a process if:
530 * (1) it's the process that's doing the tracing,
531 */
532 if (proc_getpid(traced_procp) == proc_getpid(cur_procp)) {
533 *errp = EINVAL;
534 return 0;
535 }
536
537 /*
538 * (2) it's already being traced, or
539 */
540 if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
541 *errp = EBUSY;
542 return 0;
543 }
544
545 if (!proc_is_third_party_debuggable_driver(traced_procp)) {
546 kauth_cred_t traced_cred;
547
548 /*
549 * (3) it's not owned by you, or is set-id on exec
550 * (unless you're root).
551 */
552 traced_cred = kauth_cred_proc_ref(traced_procp);
553 if ((kauth_cred_getruid(creds) != kauth_cred_getruid(traced_cred) ||
554 ISSET(traced_procp->p_flag, P_SUGID)) &&
555 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
556 kauth_cred_unref(&traced_cred);
557 *errp = my_err;
558 return 0;
559 }
560 kauth_cred_unref(&traced_cred);
561 }
562
563 if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
564 *errp = EPERM;
565 return 0;
566 }
567
568 if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
569 *errp = EBUSY;
570 return 0;
571 }
572
573 #if CONFIG_MACF
574 struct proc_ident cur_ident = proc_ident_with_policy(cur_procp, IDENT_VALIDATION_PROC_EXACT);
575 struct proc_ident traced_ident = proc_ident_with_policy(traced_procp, IDENT_VALIDATION_PROC_EXACT);
576 kauth_cred_t cur_cred = kauth_cred_proc_ref(cur_procp);
577
578 /*
579 * Drop the proc reference to avoid a deadlock during an upcall and find
580 * (reference) the proc again so our caller can keep using it.
581 */
582 proc_rele(traced_procp);
583 my_err = mac_proc_check_debug(&cur_ident, cur_cred, &traced_ident);
584 kauth_cred_unref(&cur_cred);
585
586 if (proc_find_ident(&traced_ident) == PROC_NULL) {
587 *errp = ESRCH;
588 return 0;
589 }
590 /* restored ref on traced_procp */
591 if (my_err != 0) {
592 *errp = my_err;
593 return 0;
594 }
595 #endif
596 return 1;
597 }
598