1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993
5 * The Regents of the University of California.
6 * (c) UNIX System Laboratories, Inc.
7 * Copyright (c) 2000-2001 Robert N. M. Watson.
8 * All rights reserved.
9 *
10 * All or some portions of this file are derived from material licensed
11 * to the University of California by American Telephone and Telegraph
12 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
13 * the permission of UNIX System Laboratories, Inc.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 */
39
40 /*
41 * System calls related to processes and protection
42 */
43
44 #include <sys/cdefs.h>
45 #include "opt_inet.h"
46 #include "opt_inet6.h"
47
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/acct.h>
51 #include <sys/kdb.h>
52 #include <sys/kernel.h>
53 #include <sys/lock.h>
54 #include <sys/loginclass.h>
55 #include <sys/malloc.h>
56 #include <sys/mutex.h>
57 #include <sys/ptrace.h>
58 #include <sys/refcount.h>
59 #include <sys/sx.h>
60 #include <sys/priv.h>
61 #include <sys/proc.h>
62 #ifdef COMPAT_43
63 #include <sys/sysent.h>
64 #endif
65 #include <sys/sysproto.h>
66 #include <sys/jail.h>
67 #include <sys/racct.h>
68 #include <sys/rctl.h>
69 #include <sys/resourcevar.h>
70 #include <sys/socket.h>
71 #include <sys/socketvar.h>
72 #include <sys/syscallsubr.h>
73 #include <sys/sysctl.h>
74
75 #include <vm/uma.h>
76
77 #ifdef REGRESSION
78 FEATURE(regression,
79 "Kernel support for interfaces necessary for regression testing (SECURITY RISK!)");
80 #endif
81
82 #include <security/audit/audit.h>
83 #include <security/mac/mac_framework.h>
84
85 static MALLOC_DEFINE(M_CRED, "cred", "credentials");
86
87 SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
88 "BSD security policy");
89
90 static void crfree_final(struct ucred *cr);
91 static void crsetgroups_locked(struct ucred *cr, int ngrp,
92 gid_t *groups);
93
94 static int cr_canseeotheruids(struct ucred *u1, struct ucred *u2);
95 static int cr_canseeothergids(struct ucred *u1, struct ucred *u2);
96 static int cr_canseejailproc(struct ucred *u1, struct ucred *u2);
97
98 #ifndef _SYS_SYSPROTO_H_
99 struct getpid_args {
100 int dummy;
101 };
102 #endif
103 /* ARGSUSED */
104 int
sys_getpid(struct thread * td,struct getpid_args * uap)105 sys_getpid(struct thread *td, struct getpid_args *uap)
106 {
107 struct proc *p = td->td_proc;
108
109 td->td_retval[0] = p->p_pid;
110 #if defined(COMPAT_43)
111 if (SV_PROC_FLAG(p, SV_AOUT))
112 td->td_retval[1] = kern_getppid(td);
113 #endif
114 return (0);
115 }
116
117 #ifndef _SYS_SYSPROTO_H_
118 struct getppid_args {
119 int dummy;
120 };
121 #endif
122 /* ARGSUSED */
123 int
sys_getppid(struct thread * td,struct getppid_args * uap)124 sys_getppid(struct thread *td, struct getppid_args *uap)
125 {
126
127 td->td_retval[0] = kern_getppid(td);
128 return (0);
129 }
130
131 int
kern_getppid(struct thread * td)132 kern_getppid(struct thread *td)
133 {
134 struct proc *p = td->td_proc;
135
136 return (p->p_oppid);
137 }
138
139 /*
140 * Get process group ID; note that POSIX getpgrp takes no parameter.
141 */
142 #ifndef _SYS_SYSPROTO_H_
143 struct getpgrp_args {
144 int dummy;
145 };
146 #endif
147 int
sys_getpgrp(struct thread * td,struct getpgrp_args * uap)148 sys_getpgrp(struct thread *td, struct getpgrp_args *uap)
149 {
150 struct proc *p = td->td_proc;
151
152 PROC_LOCK(p);
153 td->td_retval[0] = p->p_pgrp->pg_id;
154 PROC_UNLOCK(p);
155 return (0);
156 }
157
158 /* Get an arbitrary pid's process group id */
159 #ifndef _SYS_SYSPROTO_H_
160 struct getpgid_args {
161 pid_t pid;
162 };
163 #endif
164 int
sys_getpgid(struct thread * td,struct getpgid_args * uap)165 sys_getpgid(struct thread *td, struct getpgid_args *uap)
166 {
167 struct proc *p;
168 int error;
169
170 if (uap->pid == 0) {
171 p = td->td_proc;
172 PROC_LOCK(p);
173 } else {
174 p = pfind(uap->pid);
175 if (p == NULL)
176 return (ESRCH);
177 error = p_cansee(td, p);
178 if (error) {
179 PROC_UNLOCK(p);
180 return (error);
181 }
182 }
183 td->td_retval[0] = p->p_pgrp->pg_id;
184 PROC_UNLOCK(p);
185 return (0);
186 }
187
188 /*
189 * Get an arbitrary pid's session id.
190 */
191 #ifndef _SYS_SYSPROTO_H_
192 struct getsid_args {
193 pid_t pid;
194 };
195 #endif
196 int
sys_getsid(struct thread * td,struct getsid_args * uap)197 sys_getsid(struct thread *td, struct getsid_args *uap)
198 {
199
200 return (kern_getsid(td, uap->pid));
201 }
202
203 int
kern_getsid(struct thread * td,pid_t pid)204 kern_getsid(struct thread *td, pid_t pid)
205 {
206 struct proc *p;
207 int error;
208
209 if (pid == 0) {
210 p = td->td_proc;
211 PROC_LOCK(p);
212 } else {
213 p = pfind(pid);
214 if (p == NULL)
215 return (ESRCH);
216 error = p_cansee(td, p);
217 if (error) {
218 PROC_UNLOCK(p);
219 return (error);
220 }
221 }
222 td->td_retval[0] = p->p_session->s_sid;
223 PROC_UNLOCK(p);
224 return (0);
225 }
226
227 #ifndef _SYS_SYSPROTO_H_
228 struct getuid_args {
229 int dummy;
230 };
231 #endif
232 /* ARGSUSED */
233 int
sys_getuid(struct thread * td,struct getuid_args * uap)234 sys_getuid(struct thread *td, struct getuid_args *uap)
235 {
236
237 td->td_retval[0] = td->td_ucred->cr_ruid;
238 #if defined(COMPAT_43)
239 td->td_retval[1] = td->td_ucred->cr_uid;
240 #endif
241 return (0);
242 }
243
244 #ifndef _SYS_SYSPROTO_H_
245 struct geteuid_args {
246 int dummy;
247 };
248 #endif
249 /* ARGSUSED */
250 int
sys_geteuid(struct thread * td,struct geteuid_args * uap)251 sys_geteuid(struct thread *td, struct geteuid_args *uap)
252 {
253
254 td->td_retval[0] = td->td_ucred->cr_uid;
255 return (0);
256 }
257
258 #ifndef _SYS_SYSPROTO_H_
259 struct getgid_args {
260 int dummy;
261 };
262 #endif
263 /* ARGSUSED */
264 int
sys_getgid(struct thread * td,struct getgid_args * uap)265 sys_getgid(struct thread *td, struct getgid_args *uap)
266 {
267
268 td->td_retval[0] = td->td_ucred->cr_rgid;
269 #if defined(COMPAT_43)
270 td->td_retval[1] = td->td_ucred->cr_groups[0];
271 #endif
272 return (0);
273 }
274
275 /*
276 * Get effective group ID. The "egid" is groups[0], and could be obtained
277 * via getgroups. This syscall exists because it is somewhat painful to do
278 * correctly in a library function.
279 */
280 #ifndef _SYS_SYSPROTO_H_
281 struct getegid_args {
282 int dummy;
283 };
284 #endif
285 /* ARGSUSED */
286 int
sys_getegid(struct thread * td,struct getegid_args * uap)287 sys_getegid(struct thread *td, struct getegid_args *uap)
288 {
289
290 td->td_retval[0] = td->td_ucred->cr_groups[0];
291 return (0);
292 }
293
294 #ifndef _SYS_SYSPROTO_H_
295 struct getgroups_args {
296 int gidsetsize;
297 gid_t *gidset;
298 };
299 #endif
300 int
sys_getgroups(struct thread * td,struct getgroups_args * uap)301 sys_getgroups(struct thread *td, struct getgroups_args *uap)
302 {
303 struct ucred *cred;
304 int ngrp, error;
305
306 cred = td->td_ucred;
307 ngrp = cred->cr_ngroups;
308
309 if (uap->gidsetsize == 0) {
310 error = 0;
311 goto out;
312 }
313 if (uap->gidsetsize < ngrp)
314 return (EINVAL);
315
316 error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t));
317 out:
318 td->td_retval[0] = ngrp;
319 return (error);
320 }
321
322 #ifndef _SYS_SYSPROTO_H_
323 struct setsid_args {
324 int dummy;
325 };
326 #endif
327 /* ARGSUSED */
328 int
sys_setsid(struct thread * td,struct setsid_args * uap)329 sys_setsid(struct thread *td, struct setsid_args *uap)
330 {
331 struct pgrp *pgrp;
332 int error;
333 struct proc *p = td->td_proc;
334 struct pgrp *newpgrp;
335 struct session *newsess;
336
337 pgrp = NULL;
338
339 newpgrp = uma_zalloc(pgrp_zone, M_WAITOK);
340 newsess = malloc(sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO);
341
342 again:
343 error = 0;
344 sx_xlock(&proctree_lock);
345
346 if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) {
347 if (pgrp != NULL)
348 PGRP_UNLOCK(pgrp);
349 error = EPERM;
350 } else {
351 error = enterpgrp(p, p->p_pid, newpgrp, newsess);
352 if (error == ERESTART)
353 goto again;
354 MPASS(error == 0);
355 td->td_retval[0] = p->p_pid;
356 newpgrp = NULL;
357 newsess = NULL;
358 }
359
360 sx_xunlock(&proctree_lock);
361
362 uma_zfree(pgrp_zone, newpgrp);
363 free(newsess, M_SESSION);
364
365 return (error);
366 }
367
368 /*
369 * set process group (setpgid/old setpgrp)
370 *
371 * caller does setpgid(targpid, targpgid)
372 *
373 * pid must be caller or child of caller (ESRCH)
374 * if a child
375 * pid must be in same session (EPERM)
376 * pid can't have done an exec (EACCES)
377 * if pgid != pid
378 * there must exist some pid in same session having pgid (EPERM)
379 * pid must not be session leader (EPERM)
380 */
381 #ifndef _SYS_SYSPROTO_H_
382 struct setpgid_args {
383 int pid; /* target process id */
384 int pgid; /* target pgrp id */
385 };
386 #endif
387 /* ARGSUSED */
388 int
sys_setpgid(struct thread * td,struct setpgid_args * uap)389 sys_setpgid(struct thread *td, struct setpgid_args *uap)
390 {
391 struct proc *curp = td->td_proc;
392 struct proc *targp; /* target process */
393 struct pgrp *pgrp; /* target pgrp */
394 int error;
395 struct pgrp *newpgrp;
396
397 if (uap->pgid < 0)
398 return (EINVAL);
399
400 newpgrp = uma_zalloc(pgrp_zone, M_WAITOK);
401
402 again:
403 error = 0;
404
405 sx_xlock(&proctree_lock);
406 if (uap->pid != 0 && uap->pid != curp->p_pid) {
407 if ((targp = pfind(uap->pid)) == NULL) {
408 error = ESRCH;
409 goto done;
410 }
411 if (!inferior(targp)) {
412 PROC_UNLOCK(targp);
413 error = ESRCH;
414 goto done;
415 }
416 if ((error = p_cansee(td, targp))) {
417 PROC_UNLOCK(targp);
418 goto done;
419 }
420 if (targp->p_pgrp == NULL ||
421 targp->p_session != curp->p_session) {
422 PROC_UNLOCK(targp);
423 error = EPERM;
424 goto done;
425 }
426 if (targp->p_flag & P_EXEC) {
427 PROC_UNLOCK(targp);
428 error = EACCES;
429 goto done;
430 }
431 PROC_UNLOCK(targp);
432 } else
433 targp = curp;
434 if (SESS_LEADER(targp)) {
435 error = EPERM;
436 goto done;
437 }
438 if (uap->pgid == 0)
439 uap->pgid = targp->p_pid;
440 if ((pgrp = pgfind(uap->pgid)) == NULL) {
441 if (uap->pgid == targp->p_pid) {
442 error = enterpgrp(targp, uap->pgid, newpgrp,
443 NULL);
444 if (error == 0)
445 newpgrp = NULL;
446 } else
447 error = EPERM;
448 } else {
449 if (pgrp == targp->p_pgrp) {
450 PGRP_UNLOCK(pgrp);
451 goto done;
452 }
453 if (pgrp->pg_id != targp->p_pid &&
454 pgrp->pg_session != curp->p_session) {
455 PGRP_UNLOCK(pgrp);
456 error = EPERM;
457 goto done;
458 }
459 PGRP_UNLOCK(pgrp);
460 error = enterthispgrp(targp, pgrp);
461 }
462 done:
463 KASSERT(error == 0 || newpgrp != NULL,
464 ("setpgid failed and newpgrp is NULL"));
465 if (error == ERESTART)
466 goto again;
467 sx_xunlock(&proctree_lock);
468 uma_zfree(pgrp_zone, newpgrp);
469 return (error);
470 }
471
472 /*
473 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD
474 * compatible. It says that setting the uid/gid to euid/egid is a special
475 * case of "appropriate privilege". Once the rules are expanded out, this
476 * basically means that setuid(nnn) sets all three id's, in all permitted
477 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid())
478 * does not set the saved id - this is dangerous for traditional BSD
479 * programs. For this reason, we *really* do not want to set
480 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2.
481 */
482 #define POSIX_APPENDIX_B_4_2_2
483
484 #ifndef _SYS_SYSPROTO_H_
485 struct setuid_args {
486 uid_t uid;
487 };
488 #endif
489 /* ARGSUSED */
490 int
sys_setuid(struct thread * td,struct setuid_args * uap)491 sys_setuid(struct thread *td, struct setuid_args *uap)
492 {
493 struct proc *p = td->td_proc;
494 struct ucred *newcred, *oldcred;
495 uid_t uid;
496 struct uidinfo *uip;
497 int error;
498
499 uid = uap->uid;
500 AUDIT_ARG_UID(uid);
501 newcred = crget();
502 uip = uifind(uid);
503 PROC_LOCK(p);
504 /*
505 * Copy credentials so other references do not see our changes.
506 */
507 oldcred = crcopysafe(p, newcred);
508
509 #ifdef MAC
510 error = mac_cred_check_setuid(oldcred, uid);
511 if (error)
512 goto fail;
513 #endif
514
515 /*
516 * See if we have "permission" by POSIX 1003.1 rules.
517 *
518 * Note that setuid(geteuid()) is a special case of
519 * "appropriate privileges" in appendix B.4.2.2. We need
520 * to use this clause to be compatible with traditional BSD
521 * semantics. Basically, it means that "setuid(xx)" sets all
522 * three id's (assuming you have privs).
523 *
524 * Notes on the logic. We do things in three steps.
525 * 1: We determine if the euid is going to change, and do EPERM
526 * right away. We unconditionally change the euid later if this
527 * test is satisfied, simplifying that part of the logic.
528 * 2: We determine if the real and/or saved uids are going to
529 * change. Determined by compile options.
530 * 3: Change euid last. (after tests in #2 for "appropriate privs")
531 */
532 if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */
533 #ifdef _POSIX_SAVED_IDS
534 uid != oldcred->cr_svuid && /* allow setuid(saved gid) */
535 #endif
536 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
537 uid != oldcred->cr_uid && /* allow setuid(geteuid()) */
538 #endif
539 (error = priv_check_cred(oldcred, PRIV_CRED_SETUID)) != 0)
540 goto fail;
541
542 #ifdef _POSIX_SAVED_IDS
543 /*
544 * Do we have "appropriate privileges" (are we root or uid == euid)
545 * If so, we are changing the real uid and/or saved uid.
546 */
547 if (
548 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */
549 uid == oldcred->cr_uid ||
550 #endif
551 /* We are using privs. */
552 priv_check_cred(oldcred, PRIV_CRED_SETUID) == 0)
553 #endif
554 {
555 /*
556 * Set the real uid and transfer proc count to new user.
557 */
558 if (uid != oldcred->cr_ruid) {
559 change_ruid(newcred, uip);
560 setsugid(p);
561 }
562 /*
563 * Set saved uid
564 *
565 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as
566 * the security of seteuid() depends on it. B.4.2.2 says it
567 * is important that we should do this.
568 */
569 if (uid != oldcred->cr_svuid) {
570 change_svuid(newcred, uid);
571 setsugid(p);
572 }
573 }
574
575 /*
576 * In all permitted cases, we are changing the euid.
577 */
578 if (uid != oldcred->cr_uid) {
579 change_euid(newcred, uip);
580 setsugid(p);
581 }
582 proc_set_cred(p, newcred);
583 #ifdef RACCT
584 racct_proc_ucred_changed(p, oldcred, newcred);
585 crhold(newcred);
586 #endif
587 PROC_UNLOCK(p);
588 #ifdef RCTL
589 rctl_proc_ucred_changed(p, newcred);
590 crfree(newcred);
591 #endif
592 uifree(uip);
593 crfree(oldcred);
594 return (0);
595
596 fail:
597 PROC_UNLOCK(p);
598 uifree(uip);
599 crfree(newcred);
600 return (error);
601 }
602
603 #ifndef _SYS_SYSPROTO_H_
604 struct seteuid_args {
605 uid_t euid;
606 };
607 #endif
608 /* ARGSUSED */
609 int
sys_seteuid(struct thread * td,struct seteuid_args * uap)610 sys_seteuid(struct thread *td, struct seteuid_args *uap)
611 {
612 struct proc *p = td->td_proc;
613 struct ucred *newcred, *oldcred;
614 uid_t euid;
615 struct uidinfo *euip;
616 int error;
617
618 euid = uap->euid;
619 AUDIT_ARG_EUID(euid);
620 newcred = crget();
621 euip = uifind(euid);
622 PROC_LOCK(p);
623 /*
624 * Copy credentials so other references do not see our changes.
625 */
626 oldcred = crcopysafe(p, newcred);
627
628 #ifdef MAC
629 error = mac_cred_check_seteuid(oldcred, euid);
630 if (error)
631 goto fail;
632 #endif
633
634 if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */
635 euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */
636 (error = priv_check_cred(oldcred, PRIV_CRED_SETEUID)) != 0)
637 goto fail;
638
639 /*
640 * Everything's okay, do it.
641 */
642 if (oldcred->cr_uid != euid) {
643 change_euid(newcred, euip);
644 setsugid(p);
645 }
646 proc_set_cred(p, newcred);
647 PROC_UNLOCK(p);
648 uifree(euip);
649 crfree(oldcred);
650 return (0);
651
652 fail:
653 PROC_UNLOCK(p);
654 uifree(euip);
655 crfree(newcred);
656 return (error);
657 }
658
659 #ifndef _SYS_SYSPROTO_H_
660 struct setgid_args {
661 gid_t gid;
662 };
663 #endif
664 /* ARGSUSED */
665 int
sys_setgid(struct thread * td,struct setgid_args * uap)666 sys_setgid(struct thread *td, struct setgid_args *uap)
667 {
668 struct proc *p = td->td_proc;
669 struct ucred *newcred, *oldcred;
670 gid_t gid;
671 int error;
672
673 gid = uap->gid;
674 AUDIT_ARG_GID(gid);
675 newcred = crget();
676 PROC_LOCK(p);
677 oldcred = crcopysafe(p, newcred);
678
679 #ifdef MAC
680 error = mac_cred_check_setgid(oldcred, gid);
681 if (error)
682 goto fail;
683 #endif
684
685 /*
686 * See if we have "permission" by POSIX 1003.1 rules.
687 *
688 * Note that setgid(getegid()) is a special case of
689 * "appropriate privileges" in appendix B.4.2.2. We need
690 * to use this clause to be compatible with traditional BSD
691 * semantics. Basically, it means that "setgid(xx)" sets all
692 * three id's (assuming you have privs).
693 *
694 * For notes on the logic here, see setuid() above.
695 */
696 if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */
697 #ifdef _POSIX_SAVED_IDS
698 gid != oldcred->cr_svgid && /* allow setgid(saved gid) */
699 #endif
700 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
701 gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */
702 #endif
703 (error = priv_check_cred(oldcred, PRIV_CRED_SETGID)) != 0)
704 goto fail;
705
706 #ifdef _POSIX_SAVED_IDS
707 /*
708 * Do we have "appropriate privileges" (are we root or gid == egid)
709 * If so, we are changing the real uid and saved gid.
710 */
711 if (
712 #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */
713 gid == oldcred->cr_groups[0] ||
714 #endif
715 /* We are using privs. */
716 priv_check_cred(oldcred, PRIV_CRED_SETGID) == 0)
717 #endif
718 {
719 /*
720 * Set real gid
721 */
722 if (oldcred->cr_rgid != gid) {
723 change_rgid(newcred, gid);
724 setsugid(p);
725 }
726 /*
727 * Set saved gid
728 *
729 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as
730 * the security of setegid() depends on it. B.4.2.2 says it
731 * is important that we should do this.
732 */
733 if (oldcred->cr_svgid != gid) {
734 change_svgid(newcred, gid);
735 setsugid(p);
736 }
737 }
738 /*
739 * In all cases permitted cases, we are changing the egid.
740 * Copy credentials so other references do not see our changes.
741 */
742 if (oldcred->cr_groups[0] != gid) {
743 change_egid(newcred, gid);
744 setsugid(p);
745 }
746 proc_set_cred(p, newcred);
747 PROC_UNLOCK(p);
748 crfree(oldcred);
749 return (0);
750
751 fail:
752 PROC_UNLOCK(p);
753 crfree(newcred);
754 return (error);
755 }
756
757 #ifndef _SYS_SYSPROTO_H_
758 struct setegid_args {
759 gid_t egid;
760 };
761 #endif
762 /* ARGSUSED */
763 int
sys_setegid(struct thread * td,struct setegid_args * uap)764 sys_setegid(struct thread *td, struct setegid_args *uap)
765 {
766 struct proc *p = td->td_proc;
767 struct ucred *newcred, *oldcred;
768 gid_t egid;
769 int error;
770
771 egid = uap->egid;
772 AUDIT_ARG_EGID(egid);
773 newcred = crget();
774 PROC_LOCK(p);
775 oldcred = crcopysafe(p, newcred);
776
777 #ifdef MAC
778 error = mac_cred_check_setegid(oldcred, egid);
779 if (error)
780 goto fail;
781 #endif
782
783 if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */
784 egid != oldcred->cr_svgid && /* allow setegid(saved gid) */
785 (error = priv_check_cred(oldcred, PRIV_CRED_SETEGID)) != 0)
786 goto fail;
787
788 if (oldcred->cr_groups[0] != egid) {
789 change_egid(newcred, egid);
790 setsugid(p);
791 }
792 proc_set_cred(p, newcred);
793 PROC_UNLOCK(p);
794 crfree(oldcred);
795 return (0);
796
797 fail:
798 PROC_UNLOCK(p);
799 crfree(newcred);
800 return (error);
801 }
802
803 #ifndef _SYS_SYSPROTO_H_
804 struct setgroups_args {
805 int gidsetsize;
806 gid_t *gidset;
807 };
808 #endif
809 /* ARGSUSED */
810 int
sys_setgroups(struct thread * td,struct setgroups_args * uap)811 sys_setgroups(struct thread *td, struct setgroups_args *uap)
812 {
813 gid_t smallgroups[XU_NGROUPS];
814 gid_t *groups;
815 int gidsetsize, error;
816
817 gidsetsize = uap->gidsetsize;
818 if (gidsetsize > ngroups_max + 1 || gidsetsize < 0)
819 return (EINVAL);
820
821 if (gidsetsize > XU_NGROUPS)
822 groups = malloc(gidsetsize * sizeof(gid_t), M_TEMP, M_WAITOK);
823 else
824 groups = smallgroups;
825
826 error = copyin(uap->gidset, groups, gidsetsize * sizeof(gid_t));
827 if (error == 0)
828 error = kern_setgroups(td, gidsetsize, groups);
829
830 if (gidsetsize > XU_NGROUPS)
831 free(groups, M_TEMP);
832 return (error);
833 }
834
835 int
kern_setgroups(struct thread * td,u_int ngrp,gid_t * groups)836 kern_setgroups(struct thread *td, u_int ngrp, gid_t *groups)
837 {
838 struct proc *p = td->td_proc;
839 struct ucred *newcred, *oldcred;
840 int error;
841
842 MPASS(ngrp <= ngroups_max + 1);
843 AUDIT_ARG_GROUPSET(groups, ngrp);
844 newcred = crget();
845 crextend(newcred, ngrp);
846 PROC_LOCK(p);
847 oldcred = crcopysafe(p, newcred);
848
849 #ifdef MAC
850 error = mac_cred_check_setgroups(oldcred, ngrp, groups);
851 if (error)
852 goto fail;
853 #endif
854
855 error = priv_check_cred(oldcred, PRIV_CRED_SETGROUPS);
856 if (error)
857 goto fail;
858
859 if (ngrp == 0) {
860 /*
861 * setgroups(0, NULL) is a legitimate way of clearing the
862 * groups vector on non-BSD systems (which generally do not
863 * have the egid in the groups[0]). We risk security holes
864 * when running non-BSD software if we do not do the same.
865 */
866 newcred->cr_ngroups = 1;
867 } else {
868 crsetgroups_locked(newcred, ngrp, groups);
869 }
870 setsugid(p);
871 proc_set_cred(p, newcred);
872 PROC_UNLOCK(p);
873 crfree(oldcred);
874 return (0);
875
876 fail:
877 PROC_UNLOCK(p);
878 crfree(newcred);
879 return (error);
880 }
881
882 #ifndef _SYS_SYSPROTO_H_
883 struct setreuid_args {
884 uid_t ruid;
885 uid_t euid;
886 };
887 #endif
888 /* ARGSUSED */
889 int
sys_setreuid(struct thread * td,struct setreuid_args * uap)890 sys_setreuid(struct thread *td, struct setreuid_args *uap)
891 {
892 struct proc *p = td->td_proc;
893 struct ucred *newcred, *oldcred;
894 uid_t euid, ruid;
895 struct uidinfo *euip, *ruip;
896 int error;
897
898 euid = uap->euid;
899 ruid = uap->ruid;
900 AUDIT_ARG_EUID(euid);
901 AUDIT_ARG_RUID(ruid);
902 newcred = crget();
903 euip = uifind(euid);
904 ruip = uifind(ruid);
905 PROC_LOCK(p);
906 oldcred = crcopysafe(p, newcred);
907
908 #ifdef MAC
909 error = mac_cred_check_setreuid(oldcred, ruid, euid);
910 if (error)
911 goto fail;
912 #endif
913
914 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid &&
915 ruid != oldcred->cr_svuid) ||
916 (euid != (uid_t)-1 && euid != oldcred->cr_uid &&
917 euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) &&
918 (error = priv_check_cred(oldcred, PRIV_CRED_SETREUID)) != 0)
919 goto fail;
920
921 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
922 change_euid(newcred, euip);
923 setsugid(p);
924 }
925 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
926 change_ruid(newcred, ruip);
927 setsugid(p);
928 }
929 if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) &&
930 newcred->cr_svuid != newcred->cr_uid) {
931 change_svuid(newcred, newcred->cr_uid);
932 setsugid(p);
933 }
934 proc_set_cred(p, newcred);
935 #ifdef RACCT
936 racct_proc_ucred_changed(p, oldcred, newcred);
937 crhold(newcred);
938 #endif
939 PROC_UNLOCK(p);
940 #ifdef RCTL
941 rctl_proc_ucred_changed(p, newcred);
942 crfree(newcred);
943 #endif
944 uifree(ruip);
945 uifree(euip);
946 crfree(oldcred);
947 return (0);
948
949 fail:
950 PROC_UNLOCK(p);
951 uifree(ruip);
952 uifree(euip);
953 crfree(newcred);
954 return (error);
955 }
956
957 #ifndef _SYS_SYSPROTO_H_
958 struct setregid_args {
959 gid_t rgid;
960 gid_t egid;
961 };
962 #endif
963 /* ARGSUSED */
964 int
sys_setregid(struct thread * td,struct setregid_args * uap)965 sys_setregid(struct thread *td, struct setregid_args *uap)
966 {
967 struct proc *p = td->td_proc;
968 struct ucred *newcred, *oldcred;
969 gid_t egid, rgid;
970 int error;
971
972 egid = uap->egid;
973 rgid = uap->rgid;
974 AUDIT_ARG_EGID(egid);
975 AUDIT_ARG_RGID(rgid);
976 newcred = crget();
977 PROC_LOCK(p);
978 oldcred = crcopysafe(p, newcred);
979
980 #ifdef MAC
981 error = mac_cred_check_setregid(oldcred, rgid, egid);
982 if (error)
983 goto fail;
984 #endif
985
986 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid &&
987 rgid != oldcred->cr_svgid) ||
988 (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] &&
989 egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) &&
990 (error = priv_check_cred(oldcred, PRIV_CRED_SETREGID)) != 0)
991 goto fail;
992
993 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) {
994 change_egid(newcred, egid);
995 setsugid(p);
996 }
997 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) {
998 change_rgid(newcred, rgid);
999 setsugid(p);
1000 }
1001 if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) &&
1002 newcred->cr_svgid != newcred->cr_groups[0]) {
1003 change_svgid(newcred, newcred->cr_groups[0]);
1004 setsugid(p);
1005 }
1006 proc_set_cred(p, newcred);
1007 PROC_UNLOCK(p);
1008 crfree(oldcred);
1009 return (0);
1010
1011 fail:
1012 PROC_UNLOCK(p);
1013 crfree(newcred);
1014 return (error);
1015 }
1016
1017 /*
1018 * setresuid(ruid, euid, suid) is like setreuid except control over the saved
1019 * uid is explicit.
1020 */
1021 #ifndef _SYS_SYSPROTO_H_
1022 struct setresuid_args {
1023 uid_t ruid;
1024 uid_t euid;
1025 uid_t suid;
1026 };
1027 #endif
1028 /* ARGSUSED */
1029 int
sys_setresuid(struct thread * td,struct setresuid_args * uap)1030 sys_setresuid(struct thread *td, struct setresuid_args *uap)
1031 {
1032 struct proc *p = td->td_proc;
1033 struct ucred *newcred, *oldcred;
1034 uid_t euid, ruid, suid;
1035 struct uidinfo *euip, *ruip;
1036 int error;
1037
1038 euid = uap->euid;
1039 ruid = uap->ruid;
1040 suid = uap->suid;
1041 AUDIT_ARG_EUID(euid);
1042 AUDIT_ARG_RUID(ruid);
1043 AUDIT_ARG_SUID(suid);
1044 newcred = crget();
1045 euip = uifind(euid);
1046 ruip = uifind(ruid);
1047 PROC_LOCK(p);
1048 oldcred = crcopysafe(p, newcred);
1049
1050 #ifdef MAC
1051 error = mac_cred_check_setresuid(oldcred, ruid, euid, suid);
1052 if (error)
1053 goto fail;
1054 #endif
1055
1056 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid &&
1057 ruid != oldcred->cr_svuid &&
1058 ruid != oldcred->cr_uid) ||
1059 (euid != (uid_t)-1 && euid != oldcred->cr_ruid &&
1060 euid != oldcred->cr_svuid &&
1061 euid != oldcred->cr_uid) ||
1062 (suid != (uid_t)-1 && suid != oldcred->cr_ruid &&
1063 suid != oldcred->cr_svuid &&
1064 suid != oldcred->cr_uid)) &&
1065 (error = priv_check_cred(oldcred, PRIV_CRED_SETRESUID)) != 0)
1066 goto fail;
1067
1068 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
1069 change_euid(newcred, euip);
1070 setsugid(p);
1071 }
1072 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
1073 change_ruid(newcred, ruip);
1074 setsugid(p);
1075 }
1076 if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) {
1077 change_svuid(newcred, suid);
1078 setsugid(p);
1079 }
1080 proc_set_cred(p, newcred);
1081 #ifdef RACCT
1082 racct_proc_ucred_changed(p, oldcred, newcred);
1083 crhold(newcred);
1084 #endif
1085 PROC_UNLOCK(p);
1086 #ifdef RCTL
1087 rctl_proc_ucred_changed(p, newcred);
1088 crfree(newcred);
1089 #endif
1090 uifree(ruip);
1091 uifree(euip);
1092 crfree(oldcred);
1093 return (0);
1094
1095 fail:
1096 PROC_UNLOCK(p);
1097 uifree(ruip);
1098 uifree(euip);
1099 crfree(newcred);
1100 return (error);
1101
1102 }
1103
1104 /*
1105 * setresgid(rgid, egid, sgid) is like setregid except control over the saved
1106 * gid is explicit.
1107 */
1108 #ifndef _SYS_SYSPROTO_H_
1109 struct setresgid_args {
1110 gid_t rgid;
1111 gid_t egid;
1112 gid_t sgid;
1113 };
1114 #endif
1115 /* ARGSUSED */
1116 int
sys_setresgid(struct thread * td,struct setresgid_args * uap)1117 sys_setresgid(struct thread *td, struct setresgid_args *uap)
1118 {
1119 struct proc *p = td->td_proc;
1120 struct ucred *newcred, *oldcred;
1121 gid_t egid, rgid, sgid;
1122 int error;
1123
1124 egid = uap->egid;
1125 rgid = uap->rgid;
1126 sgid = uap->sgid;
1127 AUDIT_ARG_EGID(egid);
1128 AUDIT_ARG_RGID(rgid);
1129 AUDIT_ARG_SGID(sgid);
1130 newcred = crget();
1131 PROC_LOCK(p);
1132 oldcred = crcopysafe(p, newcred);
1133
1134 #ifdef MAC
1135 error = mac_cred_check_setresgid(oldcred, rgid, egid, sgid);
1136 if (error)
1137 goto fail;
1138 #endif
1139
1140 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid &&
1141 rgid != oldcred->cr_svgid &&
1142 rgid != oldcred->cr_groups[0]) ||
1143 (egid != (gid_t)-1 && egid != oldcred->cr_rgid &&
1144 egid != oldcred->cr_svgid &&
1145 egid != oldcred->cr_groups[0]) ||
1146 (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid &&
1147 sgid != oldcred->cr_svgid &&
1148 sgid != oldcred->cr_groups[0])) &&
1149 (error = priv_check_cred(oldcred, PRIV_CRED_SETRESGID)) != 0)
1150 goto fail;
1151
1152 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) {
1153 change_egid(newcred, egid);
1154 setsugid(p);
1155 }
1156 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) {
1157 change_rgid(newcred, rgid);
1158 setsugid(p);
1159 }
1160 if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) {
1161 change_svgid(newcred, sgid);
1162 setsugid(p);
1163 }
1164 proc_set_cred(p, newcred);
1165 PROC_UNLOCK(p);
1166 crfree(oldcred);
1167 return (0);
1168
1169 fail:
1170 PROC_UNLOCK(p);
1171 crfree(newcred);
1172 return (error);
1173 }
1174
1175 #ifndef _SYS_SYSPROTO_H_
1176 struct getresuid_args {
1177 uid_t *ruid;
1178 uid_t *euid;
1179 uid_t *suid;
1180 };
1181 #endif
1182 /* ARGSUSED */
1183 int
sys_getresuid(struct thread * td,struct getresuid_args * uap)1184 sys_getresuid(struct thread *td, struct getresuid_args *uap)
1185 {
1186 struct ucred *cred;
1187 int error1 = 0, error2 = 0, error3 = 0;
1188
1189 cred = td->td_ucred;
1190 if (uap->ruid)
1191 error1 = copyout(&cred->cr_ruid,
1192 uap->ruid, sizeof(cred->cr_ruid));
1193 if (uap->euid)
1194 error2 = copyout(&cred->cr_uid,
1195 uap->euid, sizeof(cred->cr_uid));
1196 if (uap->suid)
1197 error3 = copyout(&cred->cr_svuid,
1198 uap->suid, sizeof(cred->cr_svuid));
1199 return (error1 ? error1 : error2 ? error2 : error3);
1200 }
1201
1202 #ifndef _SYS_SYSPROTO_H_
1203 struct getresgid_args {
1204 gid_t *rgid;
1205 gid_t *egid;
1206 gid_t *sgid;
1207 };
1208 #endif
1209 /* ARGSUSED */
1210 int
sys_getresgid(struct thread * td,struct getresgid_args * uap)1211 sys_getresgid(struct thread *td, struct getresgid_args *uap)
1212 {
1213 struct ucred *cred;
1214 int error1 = 0, error2 = 0, error3 = 0;
1215
1216 cred = td->td_ucred;
1217 if (uap->rgid)
1218 error1 = copyout(&cred->cr_rgid,
1219 uap->rgid, sizeof(cred->cr_rgid));
1220 if (uap->egid)
1221 error2 = copyout(&cred->cr_groups[0],
1222 uap->egid, sizeof(cred->cr_groups[0]));
1223 if (uap->sgid)
1224 error3 = copyout(&cred->cr_svgid,
1225 uap->sgid, sizeof(cred->cr_svgid));
1226 return (error1 ? error1 : error2 ? error2 : error3);
1227 }
1228
1229 #ifndef _SYS_SYSPROTO_H_
1230 struct issetugid_args {
1231 int dummy;
1232 };
1233 #endif
1234 /* ARGSUSED */
1235 int
sys_issetugid(struct thread * td,struct issetugid_args * uap)1236 sys_issetugid(struct thread *td, struct issetugid_args *uap)
1237 {
1238 struct proc *p = td->td_proc;
1239
1240 /*
1241 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time,
1242 * we use P_SUGID because we consider changing the owners as
1243 * "tainting" as well.
1244 * This is significant for procs that start as root and "become"
1245 * a user without an exec - programs cannot know *everything*
1246 * that libc *might* have put in their data segment.
1247 */
1248 td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0;
1249 return (0);
1250 }
1251
1252 int
sys___setugid(struct thread * td,struct __setugid_args * uap)1253 sys___setugid(struct thread *td, struct __setugid_args *uap)
1254 {
1255 #ifdef REGRESSION
1256 struct proc *p;
1257
1258 p = td->td_proc;
1259 switch (uap->flag) {
1260 case 0:
1261 PROC_LOCK(p);
1262 p->p_flag &= ~P_SUGID;
1263 PROC_UNLOCK(p);
1264 return (0);
1265 case 1:
1266 PROC_LOCK(p);
1267 p->p_flag |= P_SUGID;
1268 PROC_UNLOCK(p);
1269 return (0);
1270 default:
1271 return (EINVAL);
1272 }
1273 #else /* !REGRESSION */
1274
1275 return (ENOSYS);
1276 #endif /* REGRESSION */
1277 }
1278
1279 /*
1280 * Returns whether gid designates a supplementary group in cred.
1281 */
1282 static bool
supplementary_group_member(gid_t gid,struct ucred * cred)1283 supplementary_group_member(gid_t gid, struct ucred *cred)
1284 {
1285 int l, h, m;
1286
1287 /*
1288 * Perform a binary search of the supplemental groups. This is possible
1289 * because we sort the groups in crsetgroups().
1290 */
1291 l = 1;
1292 h = cred->cr_ngroups;
1293
1294 while (l < h) {
1295 m = l + (h - l) / 2;
1296 if (cred->cr_groups[m] < gid)
1297 l = m + 1;
1298 else
1299 h = m;
1300 }
1301
1302 return (l < cred->cr_ngroups && cred->cr_groups[l] == gid);
1303 }
1304
1305 /*
1306 * Check if gid is a member of the (effective) group set (i.e., effective and
1307 * supplementary groups).
1308 */
1309 bool
groupmember(gid_t gid,struct ucred * cred)1310 groupmember(gid_t gid, struct ucred *cred)
1311 {
1312
1313 if (gid == cred->cr_groups[0])
1314 return (true);
1315
1316 return (supplementary_group_member(gid, cred));
1317 }
1318
1319 /*
1320 * Check if gid is a member of the real group set (i.e., real and supplementary
1321 * groups).
1322 */
1323 bool
realgroupmember(gid_t gid,struct ucred * cred)1324 realgroupmember(gid_t gid, struct ucred *cred)
1325 {
1326 if (gid == cred->cr_rgid)
1327 return (true);
1328
1329 return (supplementary_group_member(gid, cred));
1330 }
1331
1332 /*
1333 * Test the active securelevel against a given level. securelevel_gt()
1334 * implements (securelevel > level). securelevel_ge() implements
1335 * (securelevel >= level). Note that the logic is inverted -- these
1336 * functions return EPERM on "success" and 0 on "failure".
1337 *
1338 * Due to care taken when setting the securelevel, we know that no jail will
1339 * be less secure that its parent (or the physical system), so it is sufficient
1340 * to test the current jail only.
1341 *
1342 * XXXRW: Possibly since this has to do with privilege, it should move to
1343 * kern_priv.c.
1344 */
1345 int
securelevel_gt(struct ucred * cr,int level)1346 securelevel_gt(struct ucred *cr, int level)
1347 {
1348
1349 return (cr->cr_prison->pr_securelevel > level ? EPERM : 0);
1350 }
1351
1352 int
securelevel_ge(struct ucred * cr,int level)1353 securelevel_ge(struct ucred *cr, int level)
1354 {
1355
1356 return (cr->cr_prison->pr_securelevel >= level ? EPERM : 0);
1357 }
1358
1359 /*
1360 * 'see_other_uids' determines whether or not visibility of processes
1361 * and sockets with credentials holding different real uids is possible
1362 * using a variety of system MIBs.
1363 * XXX: data declarations should be together near the beginning of the file.
1364 */
1365 static int see_other_uids = 1;
1366 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW,
1367 &see_other_uids, 0,
1368 "Unprivileged processes may see subjects/objects with different real uid");
1369
1370 /*-
1371 * Determine if u1 "can see" the subject specified by u2, according to the
1372 * 'see_other_uids' policy.
1373 * Returns: 0 for permitted, ESRCH otherwise
1374 * Locks: none
1375 * References: *u1 and *u2 must not change during the call
1376 * u1 may equal u2, in which case only one reference is required
1377 */
1378 static int
cr_canseeotheruids(struct ucred * u1,struct ucred * u2)1379 cr_canseeotheruids(struct ucred *u1, struct ucred *u2)
1380 {
1381
1382 if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) {
1383 if (priv_check_cred(u1, PRIV_SEEOTHERUIDS) != 0)
1384 return (ESRCH);
1385 }
1386 return (0);
1387 }
1388
1389 /*
1390 * 'see_other_gids' determines whether or not visibility of processes
1391 * and sockets with credentials holding different real gids is possible
1392 * using a variety of system MIBs.
1393 * XXX: data declarations should be together near the beginning of the file.
1394 */
1395 static int see_other_gids = 1;
1396 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW,
1397 &see_other_gids, 0,
1398 "Unprivileged processes may see subjects/objects with different real gid");
1399
1400 /*
1401 * Determine if u1 can "see" the subject specified by u2, according to the
1402 * 'see_other_gids' policy.
1403 * Returns: 0 for permitted, ESRCH otherwise
1404 * Locks: none
1405 * References: *u1 and *u2 must not change during the call
1406 * u1 may equal u2, in which case only one reference is required
1407 */
1408 static int
cr_canseeothergids(struct ucred * u1,struct ucred * u2)1409 cr_canseeothergids(struct ucred *u1, struct ucred *u2)
1410 {
1411 if (!see_other_gids) {
1412 if (realgroupmember(u1->cr_rgid, u2))
1413 return (0);
1414
1415 for (int i = 1; i < u1->cr_ngroups; i++)
1416 if (realgroupmember(u1->cr_groups[i], u2))
1417 return (0);
1418
1419 if (priv_check_cred(u1, PRIV_SEEOTHERGIDS) != 0)
1420 return (ESRCH);
1421 }
1422
1423 return (0);
1424 }
1425
1426 /*
1427 * 'see_jail_proc' determines whether or not visibility of processes and
1428 * sockets with credentials holding different jail ids is possible using a
1429 * variety of system MIBs.
1430 *
1431 * XXX: data declarations should be together near the beginning of the file.
1432 */
1433
1434 static int see_jail_proc = 1;
1435 SYSCTL_INT(_security_bsd, OID_AUTO, see_jail_proc, CTLFLAG_RW,
1436 &see_jail_proc, 0,
1437 "Unprivileged processes may see subjects/objects with different jail ids");
1438
1439 /*-
1440 * Determine if u1 "can see" the subject specified by u2, according to the
1441 * 'see_jail_proc' policy.
1442 * Returns: 0 for permitted, ESRCH otherwise
1443 * Locks: none
1444 * References: *u1 and *u2 must not change during the call
1445 * u1 may equal u2, in which case only one reference is required
1446 */
1447 static int
cr_canseejailproc(struct ucred * u1,struct ucred * u2)1448 cr_canseejailproc(struct ucred *u1, struct ucred *u2)
1449 {
1450 if (see_jail_proc || /* Policy deactivated. */
1451 u1->cr_prison == u2->cr_prison || /* Same jail. */
1452 priv_check_cred(u1, PRIV_SEEJAILPROC) == 0) /* Privileged. */
1453 return (0);
1454
1455 return (ESRCH);
1456 }
1457
1458 /*
1459 * Helper for cr_cansee*() functions to abide by system-wide security.bsd.see_*
1460 * policies. Determines if u1 "can see" u2 according to these policies.
1461 * Returns: 0 for permitted, ESRCH otherwise
1462 */
1463 int
cr_bsd_visible(struct ucred * u1,struct ucred * u2)1464 cr_bsd_visible(struct ucred *u1, struct ucred *u2)
1465 {
1466 int error;
1467
1468 error = cr_canseeotheruids(u1, u2);
1469 if (error != 0)
1470 return (error);
1471 error = cr_canseeothergids(u1, u2);
1472 if (error != 0)
1473 return (error);
1474 error = cr_canseejailproc(u1, u2);
1475 if (error != 0)
1476 return (error);
1477 return (0);
1478 }
1479
1480 /*-
1481 * Determine if u1 "can see" the subject specified by u2.
1482 * Returns: 0 for permitted, an errno value otherwise
1483 * Locks: none
1484 * References: *u1 and *u2 must not change during the call
1485 * u1 may equal u2, in which case only one reference is required
1486 */
1487 int
cr_cansee(struct ucred * u1,struct ucred * u2)1488 cr_cansee(struct ucred *u1, struct ucred *u2)
1489 {
1490 int error;
1491
1492 if ((error = prison_check(u1, u2)))
1493 return (error);
1494 #ifdef MAC
1495 if ((error = mac_cred_check_visible(u1, u2)))
1496 return (error);
1497 #endif
1498 if ((error = cr_bsd_visible(u1, u2)))
1499 return (error);
1500 return (0);
1501 }
1502
1503 /*-
1504 * Determine if td "can see" the subject specified by p.
1505 * Returns: 0 for permitted, an errno value otherwise
1506 * Locks: Sufficient locks to protect p->p_ucred must be held. td really
1507 * should be curthread.
1508 * References: td and p must be valid for the lifetime of the call
1509 */
1510 int
p_cansee(struct thread * td,struct proc * p)1511 p_cansee(struct thread *td, struct proc *p)
1512 {
1513 /* Wrap cr_cansee() for all functionality. */
1514 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1515 PROC_LOCK_ASSERT(p, MA_OWNED);
1516
1517 if (td->td_proc == p)
1518 return (0);
1519 return (cr_cansee(td->td_ucred, p->p_ucred));
1520 }
1521
1522 /*
1523 * 'conservative_signals' prevents the delivery of a broad class of
1524 * signals by unprivileged processes to processes that have changed their
1525 * credentials since the last invocation of execve(). This can prevent
1526 * the leakage of cached information or retained privileges as a result
1527 * of a common class of signal-related vulnerabilities. However, this
1528 * may interfere with some applications that expect to be able to
1529 * deliver these signals to peer processes after having given up
1530 * privilege.
1531 */
1532 static int conservative_signals = 1;
1533 SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW,
1534 &conservative_signals, 0, "Unprivileged processes prevented from "
1535 "sending certain signals to processes whose credentials have changed");
1536 /*-
1537 * Determine whether cred may deliver the specified signal to proc.
1538 * Returns: 0 for permitted, an errno value otherwise.
1539 * Locks: A lock must be held for proc.
1540 * References: cred and proc must be valid for the lifetime of the call.
1541 */
1542 int
cr_cansignal(struct ucred * cred,struct proc * proc,int signum)1543 cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
1544 {
1545 int error;
1546
1547 PROC_LOCK_ASSERT(proc, MA_OWNED);
1548 /*
1549 * Jail semantics limit the scope of signalling to proc in the
1550 * same jail as cred, if cred is in jail.
1551 */
1552 error = prison_check(cred, proc->p_ucred);
1553 if (error)
1554 return (error);
1555 #ifdef MAC
1556 if ((error = mac_proc_check_signal(cred, proc, signum)))
1557 return (error);
1558 #endif
1559 if ((error = cr_bsd_visible(cred, proc->p_ucred)))
1560 return (error);
1561
1562 /*
1563 * UNIX signal semantics depend on the status of the P_SUGID
1564 * bit on the target process. If the bit is set, then additional
1565 * restrictions are placed on the set of available signals.
1566 */
1567 if (conservative_signals && (proc->p_flag & P_SUGID)) {
1568 switch (signum) {
1569 case 0:
1570 case SIGKILL:
1571 case SIGINT:
1572 case SIGTERM:
1573 case SIGALRM:
1574 case SIGSTOP:
1575 case SIGTTIN:
1576 case SIGTTOU:
1577 case SIGTSTP:
1578 case SIGHUP:
1579 case SIGUSR1:
1580 case SIGUSR2:
1581 /*
1582 * Generally, permit job and terminal control
1583 * signals.
1584 */
1585 break;
1586 default:
1587 /* Not permitted without privilege. */
1588 error = priv_check_cred(cred, PRIV_SIGNAL_SUGID);
1589 if (error)
1590 return (error);
1591 }
1592 }
1593
1594 /*
1595 * Generally, the target credential's ruid or svuid must match the
1596 * subject credential's ruid or euid.
1597 */
1598 if (cred->cr_ruid != proc->p_ucred->cr_ruid &&
1599 cred->cr_ruid != proc->p_ucred->cr_svuid &&
1600 cred->cr_uid != proc->p_ucred->cr_ruid &&
1601 cred->cr_uid != proc->p_ucred->cr_svuid) {
1602 error = priv_check_cred(cred, PRIV_SIGNAL_DIFFCRED);
1603 if (error)
1604 return (error);
1605 }
1606
1607 return (0);
1608 }
1609
1610 /*-
1611 * Determine whether td may deliver the specified signal to p.
1612 * Returns: 0 for permitted, an errno value otherwise
1613 * Locks: Sufficient locks to protect various components of td and p
1614 * must be held. td must be curthread, and a lock must be
1615 * held for p.
1616 * References: td and p must be valid for the lifetime of the call
1617 */
1618 int
p_cansignal(struct thread * td,struct proc * p,int signum)1619 p_cansignal(struct thread *td, struct proc *p, int signum)
1620 {
1621
1622 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1623 PROC_LOCK_ASSERT(p, MA_OWNED);
1624 if (td->td_proc == p)
1625 return (0);
1626
1627 /*
1628 * UNIX signalling semantics require that processes in the same
1629 * session always be able to deliver SIGCONT to one another,
1630 * overriding the remaining protections.
1631 */
1632 /* XXX: This will require an additional lock of some sort. */
1633 if (signum == SIGCONT && td->td_proc->p_session == p->p_session)
1634 return (0);
1635 /*
1636 * Some compat layers use SIGTHR and higher signals for
1637 * communication between different kernel threads of the same
1638 * process, so that they expect that it's always possible to
1639 * deliver them, even for suid applications where cr_cansignal() can
1640 * deny such ability for security consideration. It should be
1641 * pretty safe to do since the only way to create two processes
1642 * with the same p_leader is via rfork(2).
1643 */
1644 if (td->td_proc->p_leader != NULL && signum >= SIGTHR &&
1645 signum < SIGTHR + 4 && td->td_proc->p_leader == p->p_leader)
1646 return (0);
1647
1648 return (cr_cansignal(td->td_ucred, p, signum));
1649 }
1650
1651 /*-
1652 * Determine whether td may reschedule p.
1653 * Returns: 0 for permitted, an errno value otherwise
1654 * Locks: Sufficient locks to protect various components of td and p
1655 * must be held. td must be curthread, and a lock must
1656 * be held for p.
1657 * References: td and p must be valid for the lifetime of the call
1658 */
1659 int
p_cansched(struct thread * td,struct proc * p)1660 p_cansched(struct thread *td, struct proc *p)
1661 {
1662 int error;
1663
1664 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1665 PROC_LOCK_ASSERT(p, MA_OWNED);
1666 if (td->td_proc == p)
1667 return (0);
1668 if ((error = prison_check(td->td_ucred, p->p_ucred)))
1669 return (error);
1670 #ifdef MAC
1671 if ((error = mac_proc_check_sched(td->td_ucred, p)))
1672 return (error);
1673 #endif
1674 if ((error = cr_bsd_visible(td->td_ucred, p->p_ucred)))
1675 return (error);
1676
1677 if (td->td_ucred->cr_ruid != p->p_ucred->cr_ruid &&
1678 td->td_ucred->cr_uid != p->p_ucred->cr_ruid) {
1679 error = priv_check(td, PRIV_SCHED_DIFFCRED);
1680 if (error)
1681 return (error);
1682 }
1683 return (0);
1684 }
1685
1686 /*
1687 * Handle getting or setting the prison's unprivileged_proc_debug
1688 * value.
1689 */
1690 static int
sysctl_unprivileged_proc_debug(SYSCTL_HANDLER_ARGS)1691 sysctl_unprivileged_proc_debug(SYSCTL_HANDLER_ARGS)
1692 {
1693 int error, val;
1694
1695 val = prison_allow(req->td->td_ucred, PR_ALLOW_UNPRIV_DEBUG);
1696 error = sysctl_handle_int(oidp, &val, 0, req);
1697 if (error != 0 || req->newptr == NULL)
1698 return (error);
1699 if (val != 0 && val != 1)
1700 return (EINVAL);
1701 prison_set_allow(req->td->td_ucred, PR_ALLOW_UNPRIV_DEBUG, val);
1702 return (0);
1703 }
1704
1705 /*
1706 * The 'unprivileged_proc_debug' flag may be used to disable a variety of
1707 * unprivileged inter-process debugging services, including some procfs
1708 * functionality, ptrace(), and ktrace(). In the past, inter-process
1709 * debugging has been involved in a variety of security problems, and sites
1710 * not requiring the service might choose to disable it when hardening
1711 * systems.
1712 */
1713 SYSCTL_PROC(_security_bsd, OID_AUTO, unprivileged_proc_debug,
1714 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_SECURE |
1715 CTLFLAG_MPSAFE, 0, 0, sysctl_unprivileged_proc_debug, "I",
1716 "Unprivileged processes may use process debugging facilities");
1717
1718 /*-
1719 * Determine whether td may debug p.
1720 * Returns: 0 for permitted, an errno value otherwise
1721 * Locks: Sufficient locks to protect various components of td and p
1722 * must be held. td must be curthread, and a lock must
1723 * be held for p.
1724 * References: td and p must be valid for the lifetime of the call
1725 */
1726 int
p_candebug(struct thread * td,struct proc * p)1727 p_candebug(struct thread *td, struct proc *p)
1728 {
1729 int error, grpsubset, i, uidsubset;
1730
1731 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1732 PROC_LOCK_ASSERT(p, MA_OWNED);
1733 if (td->td_proc == p)
1734 return (0);
1735 if ((error = priv_check(td, PRIV_DEBUG_UNPRIV)))
1736 return (error);
1737 if ((error = prison_check(td->td_ucred, p->p_ucred)))
1738 return (error);
1739 #ifdef MAC
1740 if ((error = mac_proc_check_debug(td->td_ucred, p)))
1741 return (error);
1742 #endif
1743 if ((error = cr_bsd_visible(td->td_ucred, p->p_ucred)))
1744 return (error);
1745
1746 /*
1747 * Is p's group set a subset of td's effective group set? This
1748 * includes p's egid, group access list, rgid, and svgid.
1749 */
1750 grpsubset = 1;
1751 for (i = 0; i < p->p_ucred->cr_ngroups; i++) {
1752 if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) {
1753 grpsubset = 0;
1754 break;
1755 }
1756 }
1757 grpsubset = grpsubset &&
1758 groupmember(p->p_ucred->cr_rgid, td->td_ucred) &&
1759 groupmember(p->p_ucred->cr_svgid, td->td_ucred);
1760
1761 /*
1762 * Are the uids present in p's credential equal to td's
1763 * effective uid? This includes p's euid, svuid, and ruid.
1764 */
1765 uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid &&
1766 td->td_ucred->cr_uid == p->p_ucred->cr_svuid &&
1767 td->td_ucred->cr_uid == p->p_ucred->cr_ruid);
1768
1769 /*
1770 * If p's gids aren't a subset, or the uids aren't a subset,
1771 * or the credential has changed, require appropriate privilege
1772 * for td to debug p.
1773 */
1774 if (!grpsubset || !uidsubset) {
1775 error = priv_check(td, PRIV_DEBUG_DIFFCRED);
1776 if (error)
1777 return (error);
1778 }
1779
1780 /*
1781 * Has the credential of the process changed since the last exec()?
1782 */
1783 if ((p->p_flag & P_SUGID) != 0) {
1784 error = priv_check(td, PRIV_DEBUG_SUGID);
1785 if (error)
1786 return (error);
1787 }
1788
1789 /* Can't trace init when securelevel > 0. */
1790 if (p == initproc) {
1791 error = securelevel_gt(td->td_ucred, 0);
1792 if (error)
1793 return (error);
1794 }
1795
1796 /*
1797 * Can't trace a process that's currently exec'ing.
1798 *
1799 * XXX: Note, this is not a security policy decision, it's a
1800 * basic correctness/functionality decision. Therefore, this check
1801 * should be moved to the caller's of p_candebug().
1802 */
1803 if ((p->p_flag & P_INEXEC) != 0)
1804 return (EBUSY);
1805
1806 /* Denied explicitly */
1807 if ((p->p_flag2 & P2_NOTRACE) != 0) {
1808 error = priv_check(td, PRIV_DEBUG_DENIED);
1809 if (error != 0)
1810 return (error);
1811 }
1812
1813 return (0);
1814 }
1815
1816 /*-
1817 * Determine whether the subject represented by cred can "see" a socket.
1818 * Returns: 0 for permitted, ENOENT otherwise.
1819 */
1820 int
cr_canseesocket(struct ucred * cred,struct socket * so)1821 cr_canseesocket(struct ucred *cred, struct socket *so)
1822 {
1823 int error;
1824
1825 error = prison_check(cred, so->so_cred);
1826 if (error)
1827 return (ENOENT);
1828 #ifdef MAC
1829 error = mac_socket_check_visible(cred, so);
1830 if (error)
1831 return (error);
1832 #endif
1833 if (cr_bsd_visible(cred, so->so_cred))
1834 return (ENOENT);
1835
1836 return (0);
1837 }
1838
1839 /*-
1840 * Determine whether td can wait for the exit of p.
1841 * Returns: 0 for permitted, an errno value otherwise
1842 * Locks: Sufficient locks to protect various components of td and p
1843 * must be held. td must be curthread, and a lock must
1844 * be held for p.
1845 * References: td and p must be valid for the lifetime of the call
1846
1847 */
1848 int
p_canwait(struct thread * td,struct proc * p)1849 p_canwait(struct thread *td, struct proc *p)
1850 {
1851 int error;
1852
1853 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1854 PROC_LOCK_ASSERT(p, MA_OWNED);
1855 if ((error = prison_check(td->td_ucred, p->p_ucred)))
1856 return (error);
1857 #ifdef MAC
1858 if ((error = mac_proc_check_wait(td->td_ucred, p)))
1859 return (error);
1860 #endif
1861 #if 0
1862 /* XXXMAC: This could have odd effects on some shells. */
1863 if ((error = cr_bsd_visible(td->td_ucred, p->p_ucred)))
1864 return (error);
1865 #endif
1866
1867 return (0);
1868 }
1869
1870 /*
1871 * Credential management.
1872 *
1873 * struct ucred objects are rarely allocated but gain and lose references all
1874 * the time (e.g., on struct file alloc/dealloc) turning refcount updates into
1875 * a significant source of cache-line ping ponging. Common cases are worked
1876 * around by modifying thread-local counter instead if the cred to operate on
1877 * matches td_realucred.
1878 *
1879 * The counter is split into 2 parts:
1880 * - cr_users -- total count of all struct proc and struct thread objects
1881 * which have given cred in p_ucred and td_ucred respectively
1882 * - cr_ref -- the actual ref count, only valid if cr_users == 0
1883 *
1884 * If users == 0 then cr_ref behaves similarly to refcount(9), in particular if
1885 * the count reaches 0 the object is freeable.
1886 * If users > 0 and curthread->td_realucred == cred, then updates are performed
1887 * against td_ucredref.
1888 * In other cases updates are performed against cr_ref.
1889 *
1890 * Changing td_realucred into something else decrements cr_users and transfers
1891 * accumulated updates.
1892 */
1893 struct ucred *
crcowget(struct ucred * cr)1894 crcowget(struct ucred *cr)
1895 {
1896
1897 mtx_lock(&cr->cr_mtx);
1898 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
1899 __func__, cr->cr_users, cr));
1900 cr->cr_users++;
1901 cr->cr_ref++;
1902 mtx_unlock(&cr->cr_mtx);
1903 return (cr);
1904 }
1905
1906 static struct ucred *
crunuse(struct thread * td)1907 crunuse(struct thread *td)
1908 {
1909 struct ucred *cr, *crold;
1910
1911 MPASS(td->td_realucred == td->td_ucred);
1912 cr = td->td_realucred;
1913 mtx_lock(&cr->cr_mtx);
1914 cr->cr_ref += td->td_ucredref;
1915 td->td_ucredref = 0;
1916 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
1917 __func__, cr->cr_users, cr));
1918 cr->cr_users--;
1919 if (cr->cr_users == 0) {
1920 KASSERT(cr->cr_ref > 0, ("%s: ref %ld not > 0 on cred %p",
1921 __func__, cr->cr_ref, cr));
1922 crold = cr;
1923 } else {
1924 cr->cr_ref--;
1925 crold = NULL;
1926 }
1927 mtx_unlock(&cr->cr_mtx);
1928 td->td_realucred = NULL;
1929 return (crold);
1930 }
1931
1932 static void
crunusebatch(struct ucred * cr,int users,int ref)1933 crunusebatch(struct ucred *cr, int users, int ref)
1934 {
1935
1936 KASSERT(users > 0, ("%s: passed users %d not > 0 ; cred %p",
1937 __func__, users, cr));
1938 mtx_lock(&cr->cr_mtx);
1939 KASSERT(cr->cr_users >= users, ("%s: users %d not > %d on cred %p",
1940 __func__, cr->cr_users, users, cr));
1941 cr->cr_users -= users;
1942 cr->cr_ref += ref;
1943 cr->cr_ref -= users;
1944 if (cr->cr_users > 0) {
1945 mtx_unlock(&cr->cr_mtx);
1946 return;
1947 }
1948 KASSERT(cr->cr_ref >= 0, ("%s: ref %ld not >= 0 on cred %p",
1949 __func__, cr->cr_ref, cr));
1950 if (cr->cr_ref > 0) {
1951 mtx_unlock(&cr->cr_mtx);
1952 return;
1953 }
1954 crfree_final(cr);
1955 }
1956
1957 void
crcowfree(struct thread * td)1958 crcowfree(struct thread *td)
1959 {
1960 struct ucred *cr;
1961
1962 cr = crunuse(td);
1963 if (cr != NULL)
1964 crfree(cr);
1965 }
1966
1967 struct ucred *
crcowsync(void)1968 crcowsync(void)
1969 {
1970 struct thread *td;
1971 struct proc *p;
1972 struct ucred *crnew, *crold;
1973
1974 td = curthread;
1975 p = td->td_proc;
1976 PROC_LOCK_ASSERT(p, MA_OWNED);
1977
1978 MPASS(td->td_realucred == td->td_ucred);
1979 if (td->td_realucred == p->p_ucred)
1980 return (NULL);
1981
1982 crnew = crcowget(p->p_ucred);
1983 crold = crunuse(td);
1984 td->td_realucred = crnew;
1985 td->td_ucred = td->td_realucred;
1986 return (crold);
1987 }
1988
1989 /*
1990 * Batching.
1991 */
1992 void
credbatch_add(struct credbatch * crb,struct thread * td)1993 credbatch_add(struct credbatch *crb, struct thread *td)
1994 {
1995 struct ucred *cr;
1996
1997 MPASS(td->td_realucred != NULL);
1998 MPASS(td->td_realucred == td->td_ucred);
1999 MPASS(TD_GET_STATE(td) == TDS_INACTIVE);
2000 cr = td->td_realucred;
2001 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
2002 __func__, cr->cr_users, cr));
2003 if (crb->cred != cr) {
2004 if (crb->users > 0) {
2005 MPASS(crb->cred != NULL);
2006 crunusebatch(crb->cred, crb->users, crb->ref);
2007 crb->users = 0;
2008 crb->ref = 0;
2009 }
2010 }
2011 crb->cred = cr;
2012 crb->users++;
2013 crb->ref += td->td_ucredref;
2014 td->td_ucredref = 0;
2015 td->td_realucred = NULL;
2016 }
2017
2018 void
credbatch_final(struct credbatch * crb)2019 credbatch_final(struct credbatch *crb)
2020 {
2021
2022 MPASS(crb->cred != NULL);
2023 MPASS(crb->users > 0);
2024 crunusebatch(crb->cred, crb->users, crb->ref);
2025 }
2026
2027 /*
2028 * Allocate a zeroed cred structure.
2029 */
2030 struct ucred *
crget(void)2031 crget(void)
2032 {
2033 struct ucred *cr;
2034
2035 cr = malloc(sizeof(*cr), M_CRED, M_WAITOK | M_ZERO);
2036 mtx_init(&cr->cr_mtx, "cred", NULL, MTX_DEF);
2037 cr->cr_ref = 1;
2038 #ifdef AUDIT
2039 audit_cred_init(cr);
2040 #endif
2041 #ifdef MAC
2042 mac_cred_init(cr);
2043 #endif
2044 cr->cr_groups = cr->cr_smallgroups;
2045 cr->cr_agroups =
2046 sizeof(cr->cr_smallgroups) / sizeof(cr->cr_smallgroups[0]);
2047 return (cr);
2048 }
2049
2050 /*
2051 * Claim another reference to a ucred structure.
2052 */
2053 struct ucred *
crhold(struct ucred * cr)2054 crhold(struct ucred *cr)
2055 {
2056 struct thread *td;
2057
2058 td = curthread;
2059 if (__predict_true(td->td_realucred == cr)) {
2060 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
2061 __func__, cr->cr_users, cr));
2062 td->td_ucredref++;
2063 return (cr);
2064 }
2065 mtx_lock(&cr->cr_mtx);
2066 cr->cr_ref++;
2067 mtx_unlock(&cr->cr_mtx);
2068 return (cr);
2069 }
2070
2071 /*
2072 * Free a cred structure. Throws away space when ref count gets to 0.
2073 */
2074 void
crfree(struct ucred * cr)2075 crfree(struct ucred *cr)
2076 {
2077 struct thread *td;
2078
2079 td = curthread;
2080 if (__predict_true(td->td_realucred == cr)) {
2081 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
2082 __func__, cr->cr_users, cr));
2083 td->td_ucredref--;
2084 return;
2085 }
2086 mtx_lock(&cr->cr_mtx);
2087 KASSERT(cr->cr_users >= 0, ("%s: users %d not >= 0 on cred %p",
2088 __func__, cr->cr_users, cr));
2089 cr->cr_ref--;
2090 if (cr->cr_users > 0) {
2091 mtx_unlock(&cr->cr_mtx);
2092 return;
2093 }
2094 KASSERT(cr->cr_ref >= 0, ("%s: ref %ld not >= 0 on cred %p",
2095 __func__, cr->cr_ref, cr));
2096 if (cr->cr_ref > 0) {
2097 mtx_unlock(&cr->cr_mtx);
2098 return;
2099 }
2100 crfree_final(cr);
2101 }
2102
2103 static void
crfree_final(struct ucred * cr)2104 crfree_final(struct ucred *cr)
2105 {
2106
2107 KASSERT(cr->cr_users == 0, ("%s: users %d not == 0 on cred %p",
2108 __func__, cr->cr_users, cr));
2109 KASSERT(cr->cr_ref == 0, ("%s: ref %ld not == 0 on cred %p",
2110 __func__, cr->cr_ref, cr));
2111
2112 /*
2113 * Some callers of crget(), such as nfs_statfs(), allocate a temporary
2114 * credential, but don't allocate a uidinfo structure.
2115 */
2116 if (cr->cr_uidinfo != NULL)
2117 uifree(cr->cr_uidinfo);
2118 if (cr->cr_ruidinfo != NULL)
2119 uifree(cr->cr_ruidinfo);
2120 if (cr->cr_prison != NULL)
2121 prison_free(cr->cr_prison);
2122 if (cr->cr_loginclass != NULL)
2123 loginclass_free(cr->cr_loginclass);
2124 #ifdef AUDIT
2125 audit_cred_destroy(cr);
2126 #endif
2127 #ifdef MAC
2128 mac_cred_destroy(cr);
2129 #endif
2130 mtx_destroy(&cr->cr_mtx);
2131 if (cr->cr_groups != cr->cr_smallgroups)
2132 free(cr->cr_groups, M_CRED);
2133 free(cr, M_CRED);
2134 }
2135
2136 /*
2137 * Copy a ucred's contents from a template. Does not block.
2138 */
2139 void
crcopy(struct ucred * dest,struct ucred * src)2140 crcopy(struct ucred *dest, struct ucred *src)
2141 {
2142
2143 KASSERT(dest->cr_ref == 1, ("crcopy of shared ucred"));
2144 bcopy(&src->cr_startcopy, &dest->cr_startcopy,
2145 (unsigned)((caddr_t)&src->cr_endcopy -
2146 (caddr_t)&src->cr_startcopy));
2147 dest->cr_flags = src->cr_flags;
2148 crsetgroups(dest, src->cr_ngroups, src->cr_groups);
2149 uihold(dest->cr_uidinfo);
2150 uihold(dest->cr_ruidinfo);
2151 prison_hold(dest->cr_prison);
2152 loginclass_hold(dest->cr_loginclass);
2153 #ifdef AUDIT
2154 audit_cred_copy(src, dest);
2155 #endif
2156 #ifdef MAC
2157 mac_cred_copy(src, dest);
2158 #endif
2159 }
2160
2161 /*
2162 * Dup cred struct to a new held one.
2163 */
2164 struct ucred *
crdup(struct ucred * cr)2165 crdup(struct ucred *cr)
2166 {
2167 struct ucred *newcr;
2168
2169 newcr = crget();
2170 crcopy(newcr, cr);
2171 return (newcr);
2172 }
2173
2174 /*
2175 * Fill in a struct xucred based on a struct ucred.
2176 */
2177 void
cru2x(struct ucred * cr,struct xucred * xcr)2178 cru2x(struct ucred *cr, struct xucred *xcr)
2179 {
2180 int ngroups;
2181
2182 bzero(xcr, sizeof(*xcr));
2183 xcr->cr_version = XUCRED_VERSION;
2184 xcr->cr_uid = cr->cr_uid;
2185
2186 ngroups = MIN(cr->cr_ngroups, XU_NGROUPS);
2187 xcr->cr_ngroups = ngroups;
2188 bcopy(cr->cr_groups, xcr->cr_groups,
2189 ngroups * sizeof(*cr->cr_groups));
2190 }
2191
2192 void
cru2xt(struct thread * td,struct xucred * xcr)2193 cru2xt(struct thread *td, struct xucred *xcr)
2194 {
2195
2196 cru2x(td->td_ucred, xcr);
2197 xcr->cr_pid = td->td_proc->p_pid;
2198 }
2199
2200 /*
2201 * Change process credentials.
2202 * Callers are responsible for providing the reference for passed credentials
2203 * and for freeing old ones.
2204 *
2205 * Process has to be locked except when it does not have credentials (as it
2206 * should not be visible just yet) or when newcred is NULL (as this can be
2207 * only used when the process is about to be freed, at which point it should
2208 * not be visible anymore).
2209 */
2210 void
proc_set_cred(struct proc * p,struct ucred * newcred)2211 proc_set_cred(struct proc *p, struct ucred *newcred)
2212 {
2213 struct ucred *cr;
2214
2215 cr = p->p_ucred;
2216 MPASS(cr != NULL);
2217 PROC_LOCK_ASSERT(p, MA_OWNED);
2218 KASSERT(newcred->cr_users == 0, ("%s: users %d not 0 on cred %p",
2219 __func__, newcred->cr_users, newcred));
2220 mtx_lock(&cr->cr_mtx);
2221 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
2222 __func__, cr->cr_users, cr));
2223 cr->cr_users--;
2224 mtx_unlock(&cr->cr_mtx);
2225 p->p_ucred = newcred;
2226 newcred->cr_users = 1;
2227 PROC_UPDATE_COW(p);
2228 }
2229
2230 void
proc_unset_cred(struct proc * p)2231 proc_unset_cred(struct proc *p)
2232 {
2233 struct ucred *cr;
2234
2235 MPASS(p->p_state == PRS_ZOMBIE || p->p_state == PRS_NEW);
2236 cr = p->p_ucred;
2237 p->p_ucred = NULL;
2238 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
2239 __func__, cr->cr_users, cr));
2240 mtx_lock(&cr->cr_mtx);
2241 cr->cr_users--;
2242 if (cr->cr_users == 0)
2243 KASSERT(cr->cr_ref > 0, ("%s: ref %ld not > 0 on cred %p",
2244 __func__, cr->cr_ref, cr));
2245 mtx_unlock(&cr->cr_mtx);
2246 crfree(cr);
2247 }
2248
2249 struct ucred *
crcopysafe(struct proc * p,struct ucred * cr)2250 crcopysafe(struct proc *p, struct ucred *cr)
2251 {
2252 struct ucred *oldcred;
2253 int groups;
2254
2255 PROC_LOCK_ASSERT(p, MA_OWNED);
2256
2257 oldcred = p->p_ucred;
2258 while (cr->cr_agroups < oldcred->cr_agroups) {
2259 groups = oldcred->cr_agroups;
2260 PROC_UNLOCK(p);
2261 crextend(cr, groups);
2262 PROC_LOCK(p);
2263 oldcred = p->p_ucred;
2264 }
2265 crcopy(cr, oldcred);
2266
2267 return (oldcred);
2268 }
2269
2270 /*
2271 * Extend the passed in credential to hold n items.
2272 */
2273 void
crextend(struct ucred * cr,int n)2274 crextend(struct ucred *cr, int n)
2275 {
2276 int cnt;
2277
2278 /* Truncate? */
2279 if (n <= cr->cr_agroups)
2280 return;
2281
2282 /*
2283 * We extend by 2 each time since we're using a power of two
2284 * allocator until we need enough groups to fill a page.
2285 * Once we're allocating multiple pages, only allocate as many
2286 * as we actually need. The case of processes needing a
2287 * non-power of two number of pages seems more likely than
2288 * a real world process that adds thousands of groups one at a
2289 * time.
2290 */
2291 if ( n < PAGE_SIZE / sizeof(gid_t) ) {
2292 if (cr->cr_agroups == 0)
2293 cnt = MAX(1, MINALLOCSIZE / sizeof(gid_t));
2294 else
2295 cnt = cr->cr_agroups * 2;
2296
2297 while (cnt < n)
2298 cnt *= 2;
2299 } else
2300 cnt = roundup2(n, PAGE_SIZE / sizeof(gid_t));
2301
2302 /* Free the old array. */
2303 if (cr->cr_groups != cr->cr_smallgroups)
2304 free(cr->cr_groups, M_CRED);
2305
2306 cr->cr_groups = malloc(cnt * sizeof(gid_t), M_CRED, M_WAITOK | M_ZERO);
2307 cr->cr_agroups = cnt;
2308 }
2309
2310 /*
2311 * Copy groups in to a credential, preserving any necessary invariants.
2312 * Currently this includes the sorting of all supplemental gids.
2313 * crextend() must have been called before hand to ensure sufficient
2314 * space is available.
2315 */
2316 static void
crsetgroups_locked(struct ucred * cr,int ngrp,gid_t * groups)2317 crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups)
2318 {
2319 int i;
2320 int j;
2321 gid_t g;
2322
2323 KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small"));
2324
2325 bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t));
2326 cr->cr_ngroups = ngrp;
2327
2328 /*
2329 * Sort all groups except cr_groups[0] to allow groupmember to
2330 * perform a binary search.
2331 *
2332 * XXX: If large numbers of groups become common this should
2333 * be replaced with shell sort like linux uses or possibly
2334 * heap sort.
2335 */
2336 for (i = 2; i < ngrp; i++) {
2337 g = cr->cr_groups[i];
2338 for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--)
2339 cr->cr_groups[j + 1] = cr->cr_groups[j];
2340 cr->cr_groups[j + 1] = g;
2341 }
2342 }
2343
2344 /*
2345 * Copy groups in to a credential after expanding it if required.
2346 * Truncate the list to (ngroups_max + 1) if it is too large.
2347 */
2348 void
crsetgroups(struct ucred * cr,int ngrp,gid_t * groups)2349 crsetgroups(struct ucred *cr, int ngrp, gid_t *groups)
2350 {
2351
2352 if (ngrp > ngroups_max + 1)
2353 ngrp = ngroups_max + 1;
2354
2355 crextend(cr, ngrp);
2356 crsetgroups_locked(cr, ngrp, groups);
2357 }
2358
2359 /*
2360 * Get login name, if available.
2361 */
2362 #ifndef _SYS_SYSPROTO_H_
2363 struct getlogin_args {
2364 char *namebuf;
2365 u_int namelen;
2366 };
2367 #endif
2368 /* ARGSUSED */
2369 int
sys_getlogin(struct thread * td,struct getlogin_args * uap)2370 sys_getlogin(struct thread *td, struct getlogin_args *uap)
2371 {
2372 char login[MAXLOGNAME];
2373 struct proc *p = td->td_proc;
2374 size_t len;
2375
2376 if (uap->namelen > MAXLOGNAME)
2377 uap->namelen = MAXLOGNAME;
2378 PROC_LOCK(p);
2379 SESS_LOCK(p->p_session);
2380 len = strlcpy(login, p->p_session->s_login, uap->namelen) + 1;
2381 SESS_UNLOCK(p->p_session);
2382 PROC_UNLOCK(p);
2383 if (len > uap->namelen)
2384 return (ERANGE);
2385 return (copyout(login, uap->namebuf, len));
2386 }
2387
2388 /*
2389 * Set login name.
2390 */
2391 #ifndef _SYS_SYSPROTO_H_
2392 struct setlogin_args {
2393 char *namebuf;
2394 };
2395 #endif
2396 /* ARGSUSED */
2397 int
sys_setlogin(struct thread * td,struct setlogin_args * uap)2398 sys_setlogin(struct thread *td, struct setlogin_args *uap)
2399 {
2400 struct proc *p = td->td_proc;
2401 int error;
2402 char logintmp[MAXLOGNAME];
2403
2404 CTASSERT(sizeof(p->p_session->s_login) >= sizeof(logintmp));
2405
2406 error = priv_check(td, PRIV_PROC_SETLOGIN);
2407 if (error)
2408 return (error);
2409 error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL);
2410 if (error != 0) {
2411 if (error == ENAMETOOLONG)
2412 error = EINVAL;
2413 return (error);
2414 }
2415 AUDIT_ARG_LOGIN(logintmp);
2416 PROC_LOCK(p);
2417 SESS_LOCK(p->p_session);
2418 strcpy(p->p_session->s_login, logintmp);
2419 SESS_UNLOCK(p->p_session);
2420 PROC_UNLOCK(p);
2421 return (0);
2422 }
2423
2424 void
setsugid(struct proc * p)2425 setsugid(struct proc *p)
2426 {
2427
2428 PROC_LOCK_ASSERT(p, MA_OWNED);
2429 p->p_flag |= P_SUGID;
2430 }
2431
2432 /*-
2433 * Change a process's effective uid.
2434 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified.
2435 * References: newcred must be an exclusive credential reference for the
2436 * duration of the call.
2437 */
2438 void
change_euid(struct ucred * newcred,struct uidinfo * euip)2439 change_euid(struct ucred *newcred, struct uidinfo *euip)
2440 {
2441
2442 newcred->cr_uid = euip->ui_uid;
2443 uihold(euip);
2444 uifree(newcred->cr_uidinfo);
2445 newcred->cr_uidinfo = euip;
2446 }
2447
2448 /*-
2449 * Change a process's effective gid.
2450 * Side effects: newcred->cr_gid will be modified.
2451 * References: newcred must be an exclusive credential reference for the
2452 * duration of the call.
2453 */
2454 void
change_egid(struct ucred * newcred,gid_t egid)2455 change_egid(struct ucred *newcred, gid_t egid)
2456 {
2457
2458 newcred->cr_groups[0] = egid;
2459 }
2460
2461 /*-
2462 * Change a process's real uid.
2463 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo
2464 * will be updated, and the old and new cr_ruidinfo proc
2465 * counts will be updated.
2466 * References: newcred must be an exclusive credential reference for the
2467 * duration of the call.
2468 */
2469 void
change_ruid(struct ucred * newcred,struct uidinfo * ruip)2470 change_ruid(struct ucred *newcred, struct uidinfo *ruip)
2471 {
2472
2473 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0);
2474 newcred->cr_ruid = ruip->ui_uid;
2475 uihold(ruip);
2476 uifree(newcred->cr_ruidinfo);
2477 newcred->cr_ruidinfo = ruip;
2478 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0);
2479 }
2480
2481 /*-
2482 * Change a process's real gid.
2483 * Side effects: newcred->cr_rgid will be updated.
2484 * References: newcred must be an exclusive credential reference for the
2485 * duration of the call.
2486 */
2487 void
change_rgid(struct ucred * newcred,gid_t rgid)2488 change_rgid(struct ucred *newcred, gid_t rgid)
2489 {
2490
2491 newcred->cr_rgid = rgid;
2492 }
2493
2494 /*-
2495 * Change a process's saved uid.
2496 * Side effects: newcred->cr_svuid will be updated.
2497 * References: newcred must be an exclusive credential reference for the
2498 * duration of the call.
2499 */
2500 void
change_svuid(struct ucred * newcred,uid_t svuid)2501 change_svuid(struct ucred *newcred, uid_t svuid)
2502 {
2503
2504 newcred->cr_svuid = svuid;
2505 }
2506
2507 /*-
2508 * Change a process's saved gid.
2509 * Side effects: newcred->cr_svgid will be updated.
2510 * References: newcred must be an exclusive credential reference for the
2511 * duration of the call.
2512 */
2513 void
change_svgid(struct ucred * newcred,gid_t svgid)2514 change_svgid(struct ucred *newcred, gid_t svgid)
2515 {
2516
2517 newcred->cr_svgid = svgid;
2518 }
2519
2520 bool allow_ptrace = true;
2521 SYSCTL_BOOL(_security_bsd, OID_AUTO, allow_ptrace, CTLFLAG_RWTUN,
2522 &allow_ptrace, 0,
2523 "Deny ptrace(2) use by returning ENOSYS");
2524