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