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 task_t task;
122 thread_t th_act = THREAD_NULL;
123 struct uthread *ut;
124 int tr_sigexc = 0;
125 int error = 0;
126 int stopped = 0;
127
128 AUDIT_ARG(cmd, uap->req);
129 AUDIT_ARG(pid, uap->pid);
130 AUDIT_ARG(addr, uap->addr);
131 AUDIT_ARG(value32, uap->data);
132
133 if (uap->req == PT_DENY_ATTACH) {
134 #if (DEVELOPMENT || DEBUG) && !defined(XNU_TARGET_OS_OSX)
135 if (PE_i_can_has_debugger(NULL)) {
136 return 0;
137 }
138 #endif
139 proc_lock(p);
140 if (ISSET(p->p_lflag, P_LTRACED)) {
141 proc_unlock(p);
142 KERNEL_DEBUG_CONSTANT(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_FRCEXIT) | DBG_FUNC_NONE,
143 proc_getpid(p), W_EXITCODE(ENOTSUP, 0), 4, 0, 0);
144 exit1(p, W_EXITCODE(ENOTSUP, 0), retval);
145
146 thread_exception_return();
147 /* NOTREACHED */
148 }
149 SET(p->p_lflag, P_LNOATTACH);
150 proc_unlock(p);
151
152 return 0;
153 }
154
155 if (uap->req == PT_FORCEQUOTA) {
156 if (kauth_cred_issuser(kauth_cred_get())) {
157 t = current_proc();
158 OSBitOrAtomic(P_FORCEQUOTA, &t->p_flag);
159 return 0;
160 } else {
161 return EPERM;
162 }
163 }
164
165 /*
166 * Intercept and deal with "please trace me" request.
167 */
168 if (uap->req == PT_TRACE_ME) {
169 retry_trace_me: ;
170 proc_t pproc = proc_parent(p);
171 if (pproc == NULL) {
172 return EINVAL;
173 }
174 /* holding ref on pproc */
175
176 #if CONFIG_MACF
177 /*
178 * NB: Cannot call kauth_authorize_process(..., KAUTH_PROCESS_CANTRACE, ...)
179 * since that assumes the process being checked is the current process
180 * when, in this case, it is the current process's parent.
181 * Most of the other checks in cantrace() don't apply either.
182 */
183 struct proc_ident p_ident = proc_ident(p);
184 struct proc_ident pproc_ident = proc_ident(pproc);
185 kauth_cred_t pproc_cred = kauth_cred_proc_ref(pproc);
186
187 /* Release pproc and find it again after MAC call to avoid deadlock */
188 proc_rele(pproc);
189 error = mac_proc_check_debug(&pproc_ident, pproc_cred, &p_ident);
190 kauth_cred_unref(&pproc_cred);
191
192 if (error != 0) {
193 return error;
194 }
195 if (proc_find_ident(&pproc_ident) == PROC_NULL) {
196 return ESRCH;
197 }
198 /* re-holding ref on pproc */
199 #endif
200 proc_lock(p);
201 /* Make sure the process wasn't re-parented. */
202 if (p->p_ppid != proc_getpid(pproc)) {
203 proc_unlock(p);
204 proc_rele(pproc); /* pproc ref released */
205 goto retry_trace_me;
206 }
207 SET(p->p_lflag, P_LTRACED);
208 /* Non-attached case, our tracer is our parent. */
209 p->p_oppid = p->p_ppid;
210 proc_unlock(p);
211 /* Child and parent will have to be able to run modified code. */
212 cs_allow_invalid(p);
213 cs_allow_invalid(pproc);
214 proc_rele(pproc); /* pproc ref released */
215
216 return error;
217 }
218 if (uap->req == PT_SIGEXC) {
219 proc_lock(p);
220 if (ISSET(p->p_lflag, P_LTRACED)) {
221 SET(p->p_lflag, P_LSIGEXC);
222 proc_unlock(p);
223 return 0;
224 } else {
225 proc_unlock(p);
226 return EINVAL;
227 }
228 }
229
230 /*
231 * We do not want ptrace to do anything with kernel or launchd
232 */
233 if (uap->pid < 2) {
234 return EPERM;
235 }
236
237 retry_proc_find:
238 /*
239 * Locate victim, and make sure it is traceable.
240 */
241 if ((t = proc_find(uap->pid)) == NULL) {
242 return ESRCH;
243 }
244
245 /* Check if the proc has trace wait flag set */
246 if (t->p_lflag & P_LTRACE_WAIT) {
247 proc_rele(t);
248 delay(1);
249 goto retry_proc_find;
250 }
251
252 AUDIT_ARG(process, t);
253
254 task = proc_task(t);
255 if (uap->req == PT_ATTACHEXC) {
256 #pragma clang diagnostic push
257 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
258 uap->req = PT_ATTACH;
259 tr_sigexc = 1;
260 }
261 if (uap->req == PT_ATTACH) {
262 #pragma clang diagnostic pop
263 int err, cb_err;
264
265 #if !defined(XNU_TARGET_OS_OSX)
266 if (tr_sigexc == 0) {
267 error = ENOTSUP;
268 goto out;
269 }
270 #endif
271
272 err = kauth_authorize_process(kauth_cred_get(), KAUTH_PROCESS_CANTRACE,
273 t, (uintptr_t)&cb_err, 0, 0);
274
275 if (err == 0) {
276 /* it's OK to attach */
277 proc_lock(t);
278 SET(t->p_lflag, P_LTRACED);
279 if (tr_sigexc) {
280 SET(t->p_lflag, P_LSIGEXC);
281 }
282
283 t->p_oppid = t->p_ppid;
284 /* Check whether child and parent are allowed to run modified
285 * code (they'll have to) */
286 proc_unlock(t);
287 cs_allow_invalid(t);
288 cs_allow_invalid(p);
289 if (t->p_pptr != p) {
290 proc_reparentlocked(t, p, 1, 0);
291 }
292
293 proc_lock(t);
294 if (get_task_userstop(task) > 0) {
295 stopped = 1;
296 }
297 t->p_xstat = 0;
298 proc_unlock(t);
299 psignal(t, SIGSTOP);
300 /*
301 * If the process was stopped, wake up and run through
302 * issignal() again to properly connect to the tracing
303 * process.
304 */
305 if (stopped) {
306 task_resume(task);
307 }
308 error = 0;
309 goto out;
310 } else {
311 error = cb_err;
312 if (error == ESRCH) {
313 /*
314 * The target 't' is not valid anymore as it
315 * could not be found after the MAC check.
316 */
317 return error;
318 }
319 /* not allowed to attach, proper error code returned by kauth_authorize_process */
320 if (ISSET(t->p_lflag, P_LNOATTACH)) {
321 psignal(p, SIGSEGV);
322 }
323 goto out;
324 }
325 }
326
327 /*
328 * You can't do what you want to the process if:
329 * (1) It's not being traced at all,
330 */
331 proc_lock(t);
332 if (!ISSET(t->p_lflag, P_LTRACED)) {
333 proc_unlock(t);
334 error = EPERM;
335 goto out;
336 }
337
338 /*
339 * (2) it's not being traced by _you_, or
340 */
341 if (t->p_pptr != p) {
342 proc_unlock(t);
343 error = EBUSY;
344 goto out;
345 }
346
347 /*
348 * (3) it's not currently stopped.
349 */
350 if (t->p_stat != SSTOP) {
351 proc_unlock(t);
352 error = EBUSY;
353 goto out;
354 }
355
356 /*
357 * Mach version of ptrace executes request directly here,
358 * thus simplifying the interaction of ptrace and signals.
359 */
360 /* proc lock is held here */
361 switch (uap->req) {
362 case PT_DETACH:
363 if (t->p_oppid != t->p_ppid) {
364 struct proc *pp;
365
366 proc_unlock(t);
367 pp = proc_find(t->p_oppid);
368 if (pp != PROC_NULL) {
369 proc_reparentlocked(t, pp, 1, 0);
370 proc_rele(pp);
371 } else {
372 /* original parent exited while traced */
373 proc_list_lock();
374 t->p_listflag |= P_LIST_DEADPARENT;
375 proc_list_unlock();
376 proc_reparentlocked(t, initproc, 1, 0);
377 }
378 proc_lock(t);
379 }
380
381 t->p_oppid = 0;
382 CLR(t->p_lflag, P_LTRACED);
383 CLR(t->p_lflag, P_LSIGEXC);
384 proc_unlock(t);
385 goto resume;
386
387 case PT_KILL:
388 /*
389 * Tell child process to kill itself after it
390 * is resumed by adding NSIG to p_cursig. [see issig]
391 */
392 proc_unlock(t);
393 #if CONFIG_MACF
394 error = mac_proc_check_signal(p, t, SIGKILL);
395 if (0 != error) {
396 goto resume;
397 }
398 #endif
399 psignal(t, SIGKILL);
400 goto resume;
401
402 case PT_STEP: /* single step the child */
403 case PT_CONTINUE: /* continue the child */
404 proc_unlock(t);
405 th_act = (thread_t)get_firstthread(task);
406 if (th_act == THREAD_NULL) {
407 error = EINVAL;
408 goto out;
409 }
410
411 /* force use of Mach SPIs (and task_for_pid security checks) to adjust PC */
412 if (uap->addr != (user_addr_t)1) {
413 error = ENOTSUP;
414 goto out;
415 }
416
417 if ((unsigned)uap->data >= NSIG) {
418 error = EINVAL;
419 goto out;
420 }
421
422 if (uap->data != 0) {
423 #if CONFIG_MACF
424 error = mac_proc_check_signal(p, t, uap->data);
425 if (0 != error) {
426 goto out;
427 }
428 #endif
429 psignal(t, uap->data);
430 }
431
432 if (uap->req == PT_STEP) {
433 /*
434 * set trace bit
435 * we use sending SIGSTOP as a comparable security check.
436 */
437 #if CONFIG_MACF
438 error = mac_proc_check_signal(p, t, SIGSTOP);
439 if (0 != error) {
440 goto out;
441 }
442 #endif
443 if (thread_setsinglestep(th_act, 1) != KERN_SUCCESS) {
444 error = ENOTSUP;
445 goto out;
446 }
447 } else {
448 /*
449 * clear trace bit if on
450 * we use sending SIGCONT as a comparable security check.
451 */
452 #if CONFIG_MACF
453 error = mac_proc_check_signal(p, t, SIGCONT);
454 if (0 != error) {
455 goto out;
456 }
457 #endif
458 if (thread_setsinglestep(th_act, 0) != KERN_SUCCESS) {
459 error = ENOTSUP;
460 goto out;
461 }
462 }
463 resume:
464 proc_lock(t);
465 t->p_xstat = uap->data;
466 t->p_stat = SRUN;
467 if (t->sigwait) {
468 wakeup((caddr_t)&(t->sigwait));
469 proc_unlock(t);
470 if ((t->p_lflag & P_LSIGEXC) == 0) {
471 task_resume(task);
472 }
473 } else {
474 proc_unlock(t);
475 }
476
477 break;
478
479 case PT_THUPDATE: {
480 proc_unlock(t);
481 if ((unsigned)uap->data >= NSIG) {
482 error = EINVAL;
483 goto out;
484 }
485 th_act = port_name_to_thread(CAST_MACH_PORT_TO_NAME(uap->addr),
486 PORT_INTRANS_OPTIONS_NONE);
487 if (th_act == THREAD_NULL) {
488 error = ESRCH;
489 goto out;
490 }
491 ut = (uthread_t)get_bsdthread_info(th_act);
492 if (uap->data) {
493 ut->uu_siglist |= sigmask(uap->data);
494 }
495 proc_lock(t);
496 t->p_xstat = uap->data;
497 t->p_stat = SRUN;
498 proc_unlock(t);
499 error = 0;
500 }
501 break;
502 default:
503 proc_unlock(t);
504 error = EINVAL;
505 goto out;
506 }
507
508 error = 0;
509 out:
510 proc_rele(t);
511 if (th_act) {
512 thread_deallocate(th_act);
513 }
514 return error;
515 }
516
517
518 /*
519 * determine if one process (cur_procp) can trace another process (traced_procp).
520 */
521
522 int
cantrace(proc_t cur_procp,kauth_cred_t creds,proc_t traced_procp,int * errp)523 cantrace(proc_t cur_procp, kauth_cred_t creds, proc_t traced_procp, int *errp)
524 {
525 int my_err;
526 /*
527 * You can't trace a process if:
528 * (1) it's the process that's doing the tracing,
529 */
530 if (proc_getpid(traced_procp) == proc_getpid(cur_procp)) {
531 *errp = EINVAL;
532 return 0;
533 }
534
535 /*
536 * (2) it's already being traced, or
537 */
538 if (ISSET(traced_procp->p_lflag, P_LTRACED)) {
539 *errp = EBUSY;
540 return 0;
541 }
542
543 if (!proc_is_third_party_debuggable_driver(traced_procp)) {
544 kauth_cred_t traced_cred;
545
546 /*
547 * (3) it's not owned by you, or is set-id on exec
548 * (unless you're root).
549 */
550 traced_cred = kauth_cred_proc_ref(traced_procp);
551 if ((kauth_cred_getruid(creds) != kauth_cred_getruid(traced_cred) ||
552 ISSET(traced_procp->p_flag, P_SUGID)) &&
553 (my_err = suser(creds, &cur_procp->p_acflag)) != 0) {
554 kauth_cred_unref(&traced_cred);
555 *errp = my_err;
556 return 0;
557 }
558 kauth_cred_unref(&traced_cred);
559 }
560
561 if ((cur_procp->p_lflag & P_LTRACED) && isinferior(cur_procp, traced_procp)) {
562 *errp = EPERM;
563 return 0;
564 }
565
566 if (ISSET(traced_procp->p_lflag, P_LNOATTACH)) {
567 *errp = EBUSY;
568 return 0;
569 }
570
571 #if CONFIG_MACF
572 struct proc_ident cur_ident = proc_ident(cur_procp);
573 struct proc_ident traced_ident = proc_ident(traced_procp);
574 kauth_cred_t cur_cred = kauth_cred_proc_ref(cur_procp);
575
576 /*
577 * Drop the proc reference to avoid a deadlock during an upcall and find
578 * (reference) the proc again so our caller can keep using it.
579 */
580 proc_rele(traced_procp);
581 my_err = mac_proc_check_debug(&cur_ident, cur_cred, &traced_ident);
582 kauth_cred_unref(&cur_cred);
583
584 if (proc_find_ident(&traced_ident) == PROC_NULL) {
585 *errp = ESRCH;
586 return 0;
587 }
588 /* restored ref on traced_procp */
589 if (my_err != 0) {
590 *errp = my_err;
591 return 0;
592 }
593 #endif
594 return 1;
595 }
596