FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_prot.c
1 /*-
2 * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993
3 * The Regents of the University of California.
4 * (c) UNIX System Laboratories, Inc.
5 * Copyright (c) 2000-2001 Robert N. M. Watson.
6 * All rights reserved.
7 *
8 * All or some portions of this file are derived from material licensed
9 * to the University of California by American Telephone and Telegraph
10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
11 * the permission of UNIX System Laboratories, Inc.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94
38 */
39
40 /*
41 * System calls related to processes and protection
42 */
43
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD: releng/8.0/sys/kern/kern_prot.c 195741 2009-07-17 14:48:21Z jamie $");
46
47 #include "opt_compat.h"
48 #include "opt_inet.h"
49 #include "opt_inet6.h"
50
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/acct.h>
54 #include <sys/kdb.h>
55 #include <sys/kernel.h>
56 #include <sys/lock.h>
57 #include <sys/malloc.h>
58 #include <sys/mutex.h>
59 #include <sys/refcount.h>
60 #include <sys/sx.h>
61 #include <sys/priv.h>
62 #include <sys/proc.h>
63 #include <sys/sysproto.h>
64 #include <sys/jail.h>
65 #include <sys/pioctl.h>
66 #include <sys/resourcevar.h>
67 #include <sys/socket.h>
68 #include <sys/socketvar.h>
69 #include <sys/syscallsubr.h>
70 #include <sys/sysctl.h>
71
72 #if defined(INET) || defined(INET6)
73 #include <netinet/in.h>
74 #include <netinet/in_pcb.h>
75 #endif
76
77 #include <security/audit/audit.h>
78 #include <security/mac/mac_framework.h>
79
80 static MALLOC_DEFINE(M_CRED, "cred", "credentials");
81
82 SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, "BSD security policy");
83
84 static void crextend(struct ucred *cr, int n);
85 static void crsetgroups_locked(struct ucred *cr, int ngrp,
86 gid_t *groups);
87
88 #ifndef _SYS_SYSPROTO_H_
89 struct getpid_args {
90 int dummy;
91 };
92 #endif
93 /* ARGSUSED */
94 int
95 getpid(struct thread *td, struct getpid_args *uap)
96 {
97 struct proc *p = td->td_proc;
98
99 td->td_retval[0] = p->p_pid;
100 #if defined(COMPAT_43)
101 PROC_LOCK(p);
102 td->td_retval[1] = p->p_pptr->p_pid;
103 PROC_UNLOCK(p);
104 #endif
105 return (0);
106 }
107
108 #ifndef _SYS_SYSPROTO_H_
109 struct getppid_args {
110 int dummy;
111 };
112 #endif
113 /* ARGSUSED */
114 int
115 getppid(struct thread *td, struct getppid_args *uap)
116 {
117 struct proc *p = td->td_proc;
118
119 PROC_LOCK(p);
120 td->td_retval[0] = p->p_pptr->p_pid;
121 PROC_UNLOCK(p);
122 return (0);
123 }
124
125 /*
126 * Get process group ID; note that POSIX getpgrp takes no parameter.
127 */
128 #ifndef _SYS_SYSPROTO_H_
129 struct getpgrp_args {
130 int dummy;
131 };
132 #endif
133 int
134 getpgrp(struct thread *td, struct getpgrp_args *uap)
135 {
136 struct proc *p = td->td_proc;
137
138 PROC_LOCK(p);
139 td->td_retval[0] = p->p_pgrp->pg_id;
140 PROC_UNLOCK(p);
141 return (0);
142 }
143
144 /* Get an arbitary pid's process group id */
145 #ifndef _SYS_SYSPROTO_H_
146 struct getpgid_args {
147 pid_t pid;
148 };
149 #endif
150 int
151 getpgid(struct thread *td, struct getpgid_args *uap)
152 {
153 struct proc *p;
154 int error;
155
156 if (uap->pid == 0) {
157 p = td->td_proc;
158 PROC_LOCK(p);
159 } else {
160 p = pfind(uap->pid);
161 if (p == NULL)
162 return (ESRCH);
163 error = p_cansee(td, p);
164 if (error) {
165 PROC_UNLOCK(p);
166 return (error);
167 }
168 }
169 td->td_retval[0] = p->p_pgrp->pg_id;
170 PROC_UNLOCK(p);
171 return (0);
172 }
173
174 /*
175 * Get an arbitary pid's session id.
176 */
177 #ifndef _SYS_SYSPROTO_H_
178 struct getsid_args {
179 pid_t pid;
180 };
181 #endif
182 int
183 getsid(struct thread *td, struct getsid_args *uap)
184 {
185 struct proc *p;
186 int error;
187
188 if (uap->pid == 0) {
189 p = td->td_proc;
190 PROC_LOCK(p);
191 } else {
192 p = pfind(uap->pid);
193 if (p == NULL)
194 return (ESRCH);
195 error = p_cansee(td, p);
196 if (error) {
197 PROC_UNLOCK(p);
198 return (error);
199 }
200 }
201 td->td_retval[0] = p->p_session->s_sid;
202 PROC_UNLOCK(p);
203 return (0);
204 }
205
206 #ifndef _SYS_SYSPROTO_H_
207 struct getuid_args {
208 int dummy;
209 };
210 #endif
211 /* ARGSUSED */
212 int
213 getuid(struct thread *td, struct getuid_args *uap)
214 {
215
216 td->td_retval[0] = td->td_ucred->cr_ruid;
217 #if defined(COMPAT_43)
218 td->td_retval[1] = td->td_ucred->cr_uid;
219 #endif
220 return (0);
221 }
222
223 #ifndef _SYS_SYSPROTO_H_
224 struct geteuid_args {
225 int dummy;
226 };
227 #endif
228 /* ARGSUSED */
229 int
230 geteuid(struct thread *td, struct geteuid_args *uap)
231 {
232
233 td->td_retval[0] = td->td_ucred->cr_uid;
234 return (0);
235 }
236
237 #ifndef _SYS_SYSPROTO_H_
238 struct getgid_args {
239 int dummy;
240 };
241 #endif
242 /* ARGSUSED */
243 int
244 getgid(struct thread *td, struct getgid_args *uap)
245 {
246
247 td->td_retval[0] = td->td_ucred->cr_rgid;
248 #if defined(COMPAT_43)
249 td->td_retval[1] = td->td_ucred->cr_groups[0];
250 #endif
251 return (0);
252 }
253
254 /*
255 * Get effective group ID. The "egid" is groups[0], and could be obtained
256 * via getgroups. This syscall exists because it is somewhat painful to do
257 * correctly in a library function.
258 */
259 #ifndef _SYS_SYSPROTO_H_
260 struct getegid_args {
261 int dummy;
262 };
263 #endif
264 /* ARGSUSED */
265 int
266 getegid(struct thread *td, struct getegid_args *uap)
267 {
268
269 td->td_retval[0] = td->td_ucred->cr_groups[0];
270 return (0);
271 }
272
273 #ifndef _SYS_SYSPROTO_H_
274 struct getgroups_args {
275 u_int gidsetsize;
276 gid_t *gidset;
277 };
278 #endif
279 int
280 getgroups(struct thread *td, register struct getgroups_args *uap)
281 {
282 gid_t *groups;
283 u_int ngrp;
284 int error;
285
286 ngrp = MIN(uap->gidsetsize, NGROUPS);
287 groups = malloc(ngrp * sizeof(*groups), M_TEMP, M_WAITOK);
288 error = kern_getgroups(td, &ngrp, groups);
289 if (error)
290 goto out;
291 if (uap->gidsetsize > 0)
292 error = copyout(groups, uap->gidset, ngrp * sizeof(gid_t));
293 if (error == 0)
294 td->td_retval[0] = ngrp;
295 out:
296 free(groups, M_TEMP);
297 return (error);
298 }
299
300 int
301 kern_getgroups(struct thread *td, u_int *ngrp, gid_t *groups)
302 {
303 struct ucred *cred;
304
305 cred = td->td_ucred;
306 if (*ngrp == 0) {
307 *ngrp = cred->cr_ngroups;
308 return (0);
309 }
310 if (*ngrp < cred->cr_ngroups)
311 return (EINVAL);
312 *ngrp = cred->cr_ngroups;
313 bcopy(cred->cr_groups, groups, *ngrp * sizeof(gid_t));
314 return (0);
315 }
316
317 #ifndef _SYS_SYSPROTO_H_
318 struct setsid_args {
319 int dummy;
320 };
321 #endif
322 /* ARGSUSED */
323 int
324 setsid(register struct thread *td, struct setsid_args *uap)
325 {
326 struct pgrp *pgrp;
327 int error;
328 struct proc *p = td->td_proc;
329 struct pgrp *newpgrp;
330 struct session *newsess;
331
332 error = 0;
333 pgrp = NULL;
334
335 newpgrp = malloc(sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO);
336 newsess = malloc(sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO);
337
338 sx_xlock(&proctree_lock);
339
340 if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) {
341 if (pgrp != NULL)
342 PGRP_UNLOCK(pgrp);
343 error = EPERM;
344 } else {
345 (void)enterpgrp(p, p->p_pid, newpgrp, newsess);
346 td->td_retval[0] = p->p_pid;
347 newpgrp = NULL;
348 newsess = NULL;
349 }
350
351 sx_xunlock(&proctree_lock);
352
353 if (newpgrp != NULL)
354 free(newpgrp, M_PGRP);
355 if (newsess != NULL)
356 free(newsess, M_SESSION);
357
358 return (error);
359 }
360
361 /*
362 * set process group (setpgid/old setpgrp)
363 *
364 * caller does setpgid(targpid, targpgid)
365 *
366 * pid must be caller or child of caller (ESRCH)
367 * if a child
368 * pid must be in same session (EPERM)
369 * pid can't have done an exec (EACCES)
370 * if pgid != pid
371 * there must exist some pid in same session having pgid (EPERM)
372 * pid must not be session leader (EPERM)
373 */
374 #ifndef _SYS_SYSPROTO_H_
375 struct setpgid_args {
376 int pid; /* target process id */
377 int pgid; /* target pgrp id */
378 };
379 #endif
380 /* ARGSUSED */
381 int
382 setpgid(struct thread *td, register struct setpgid_args *uap)
383 {
384 struct proc *curp = td->td_proc;
385 register struct proc *targp; /* target process */
386 register struct pgrp *pgrp; /* target pgrp */
387 int error;
388 struct pgrp *newpgrp;
389
390 if (uap->pgid < 0)
391 return (EINVAL);
392
393 error = 0;
394
395 newpgrp = malloc(sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO);
396
397 sx_xlock(&proctree_lock);
398 if (uap->pid != 0 && uap->pid != curp->p_pid) {
399 if ((targp = pfind(uap->pid)) == NULL) {
400 error = ESRCH;
401 goto done;
402 }
403 if (!inferior(targp)) {
404 PROC_UNLOCK(targp);
405 error = ESRCH;
406 goto done;
407 }
408 if ((error = p_cansee(td, targp))) {
409 PROC_UNLOCK(targp);
410 goto done;
411 }
412 if (targp->p_pgrp == NULL ||
413 targp->p_session != curp->p_session) {
414 PROC_UNLOCK(targp);
415 error = EPERM;
416 goto done;
417 }
418 if (targp->p_flag & P_EXEC) {
419 PROC_UNLOCK(targp);
420 error = EACCES;
421 goto done;
422 }
423 PROC_UNLOCK(targp);
424 } else
425 targp = curp;
426 if (SESS_LEADER(targp)) {
427 error = EPERM;
428 goto done;
429 }
430 if (uap->pgid == 0)
431 uap->pgid = targp->p_pid;
432 if ((pgrp = pgfind(uap->pgid)) == NULL) {
433 if (uap->pgid == targp->p_pid) {
434 error = enterpgrp(targp, uap->pgid, newpgrp,
435 NULL);
436 if (error == 0)
437 newpgrp = NULL;
438 } else
439 error = EPERM;
440 } else {
441 if (pgrp == targp->p_pgrp) {
442 PGRP_UNLOCK(pgrp);
443 goto done;
444 }
445 if (pgrp->pg_id != targp->p_pid &&
446 pgrp->pg_session != curp->p_session) {
447 PGRP_UNLOCK(pgrp);
448 error = EPERM;
449 goto done;
450 }
451 PGRP_UNLOCK(pgrp);
452 error = enterthispgrp(targp, pgrp);
453 }
454 done:
455 sx_xunlock(&proctree_lock);
456 KASSERT((error == 0) || (newpgrp != NULL),
457 ("setpgid failed and newpgrp is NULL"));
458 if (newpgrp != NULL)
459 free(newpgrp, M_PGRP);
460 return (error);
461 }
462
463 /*
464 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD
465 * compatible. It says that setting the uid/gid to euid/egid is a special
466 * case of "appropriate privilege". Once the rules are expanded out, this
467 * basically means that setuid(nnn) sets all three id's, in all permitted
468 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid())
469 * does not set the saved id - this is dangerous for traditional BSD
470 * programs. For this reason, we *really* do not want to set
471 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2.
472 */
473 #define POSIX_APPENDIX_B_4_2_2
474
475 #ifndef _SYS_SYSPROTO_H_
476 struct setuid_args {
477 uid_t uid;
478 };
479 #endif
480 /* ARGSUSED */
481 int
482 setuid(struct thread *td, struct setuid_args *uap)
483 {
484 struct proc *p = td->td_proc;
485 struct ucred *newcred, *oldcred;
486 uid_t uid;
487 struct uidinfo *uip;
488 int error;
489
490 uid = uap->uid;
491 AUDIT_ARG_UID(uid);
492 newcred = crget();
493 uip = uifind(uid);
494 PROC_LOCK(p);
495 /*
496 * Copy credentials so other references do not see our changes.
497 */
498 oldcred = crcopysafe(p, newcred);
499
500 #ifdef MAC
501 error = mac_cred_check_setuid(oldcred, uid);
502 if (error)
503 goto fail;
504 #endif
505
506 /*
507 * See if we have "permission" by POSIX 1003.1 rules.
508 *
509 * Note that setuid(geteuid()) is a special case of
510 * "appropriate privileges" in appendix B.4.2.2. We need
511 * to use this clause to be compatible with traditional BSD
512 * semantics. Basically, it means that "setuid(xx)" sets all
513 * three id's (assuming you have privs).
514 *
515 * Notes on the logic. We do things in three steps.
516 * 1: We determine if the euid is going to change, and do EPERM
517 * right away. We unconditionally change the euid later if this
518 * test is satisfied, simplifying that part of the logic.
519 * 2: We determine if the real and/or saved uids are going to
520 * change. Determined by compile options.
521 * 3: Change euid last. (after tests in #2 for "appropriate privs")
522 */
523 if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */
524 #ifdef _POSIX_SAVED_IDS
525 uid != oldcred->cr_svuid && /* allow setuid(saved gid) */
526 #endif
527 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
528 uid != oldcred->cr_uid && /* allow setuid(geteuid()) */
529 #endif
530 (error = priv_check_cred(oldcred, PRIV_CRED_SETUID, 0)) != 0)
531 goto fail;
532
533 #ifdef _POSIX_SAVED_IDS
534 /*
535 * Do we have "appropriate privileges" (are we root or uid == euid)
536 * If so, we are changing the real uid and/or saved uid.
537 */
538 if (
539 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */
540 uid == oldcred->cr_uid ||
541 #endif
542 /* We are using privs. */
543 priv_check_cred(oldcred, PRIV_CRED_SETUID, 0) == 0)
544 #endif
545 {
546 /*
547 * Set the real uid and transfer proc count to new user.
548 */
549 if (uid != oldcred->cr_ruid) {
550 change_ruid(newcred, uip);
551 setsugid(p);
552 }
553 /*
554 * Set saved uid
555 *
556 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as
557 * the security of seteuid() depends on it. B.4.2.2 says it
558 * is important that we should do this.
559 */
560 if (uid != oldcred->cr_svuid) {
561 change_svuid(newcred, uid);
562 setsugid(p);
563 }
564 }
565
566 /*
567 * In all permitted cases, we are changing the euid.
568 */
569 if (uid != oldcred->cr_uid) {
570 change_euid(newcred, uip);
571 setsugid(p);
572 }
573 p->p_ucred = newcred;
574 PROC_UNLOCK(p);
575 uifree(uip);
576 crfree(oldcred);
577 return (0);
578
579 fail:
580 PROC_UNLOCK(p);
581 uifree(uip);
582 crfree(newcred);
583 return (error);
584 }
585
586 #ifndef _SYS_SYSPROTO_H_
587 struct seteuid_args {
588 uid_t euid;
589 };
590 #endif
591 /* ARGSUSED */
592 int
593 seteuid(struct thread *td, struct seteuid_args *uap)
594 {
595 struct proc *p = td->td_proc;
596 struct ucred *newcred, *oldcred;
597 uid_t euid;
598 struct uidinfo *euip;
599 int error;
600
601 euid = uap->euid;
602 AUDIT_ARG_EUID(euid);
603 newcred = crget();
604 euip = uifind(euid);
605 PROC_LOCK(p);
606 /*
607 * Copy credentials so other references do not see our changes.
608 */
609 oldcred = crcopysafe(p, newcred);
610
611 #ifdef MAC
612 error = mac_cred_check_seteuid(oldcred, euid);
613 if (error)
614 goto fail;
615 #endif
616
617 if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */
618 euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */
619 (error = priv_check_cred(oldcred, PRIV_CRED_SETEUID, 0)) != 0)
620 goto fail;
621
622 /*
623 * Everything's okay, do it.
624 */
625 if (oldcred->cr_uid != euid) {
626 change_euid(newcred, euip);
627 setsugid(p);
628 }
629 p->p_ucred = newcred;
630 PROC_UNLOCK(p);
631 uifree(euip);
632 crfree(oldcred);
633 return (0);
634
635 fail:
636 PROC_UNLOCK(p);
637 uifree(euip);
638 crfree(newcred);
639 return (error);
640 }
641
642 #ifndef _SYS_SYSPROTO_H_
643 struct setgid_args {
644 gid_t gid;
645 };
646 #endif
647 /* ARGSUSED */
648 int
649 setgid(struct thread *td, struct setgid_args *uap)
650 {
651 struct proc *p = td->td_proc;
652 struct ucred *newcred, *oldcred;
653 gid_t gid;
654 int error;
655
656 gid = uap->gid;
657 AUDIT_ARG_GID(gid);
658 newcred = crget();
659 PROC_LOCK(p);
660 oldcred = crcopysafe(p, newcred);
661
662 #ifdef MAC
663 error = mac_cred_check_setgid(oldcred, gid);
664 if (error)
665 goto fail;
666 #endif
667
668 /*
669 * See if we have "permission" by POSIX 1003.1 rules.
670 *
671 * Note that setgid(getegid()) is a special case of
672 * "appropriate privileges" in appendix B.4.2.2. We need
673 * to use this clause to be compatible with traditional BSD
674 * semantics. Basically, it means that "setgid(xx)" sets all
675 * three id's (assuming you have privs).
676 *
677 * For notes on the logic here, see setuid() above.
678 */
679 if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */
680 #ifdef _POSIX_SAVED_IDS
681 gid != oldcred->cr_svgid && /* allow setgid(saved gid) */
682 #endif
683 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */
684 gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */
685 #endif
686 (error = priv_check_cred(oldcred, PRIV_CRED_SETGID, 0)) != 0)
687 goto fail;
688
689 #ifdef _POSIX_SAVED_IDS
690 /*
691 * Do we have "appropriate privileges" (are we root or gid == egid)
692 * If so, we are changing the real uid and saved gid.
693 */
694 if (
695 #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */
696 gid == oldcred->cr_groups[0] ||
697 #endif
698 /* We are using privs. */
699 priv_check_cred(oldcred, PRIV_CRED_SETGID, 0) == 0)
700 #endif
701 {
702 /*
703 * Set real gid
704 */
705 if (oldcred->cr_rgid != gid) {
706 change_rgid(newcred, gid);
707 setsugid(p);
708 }
709 /*
710 * Set saved gid
711 *
712 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as
713 * the security of setegid() depends on it. B.4.2.2 says it
714 * is important that we should do this.
715 */
716 if (oldcred->cr_svgid != gid) {
717 change_svgid(newcred, gid);
718 setsugid(p);
719 }
720 }
721 /*
722 * In all cases permitted cases, we are changing the egid.
723 * Copy credentials so other references do not see our changes.
724 */
725 if (oldcred->cr_groups[0] != gid) {
726 change_egid(newcred, gid);
727 setsugid(p);
728 }
729 p->p_ucred = newcred;
730 PROC_UNLOCK(p);
731 crfree(oldcred);
732 return (0);
733
734 fail:
735 PROC_UNLOCK(p);
736 crfree(newcred);
737 return (error);
738 }
739
740 #ifndef _SYS_SYSPROTO_H_
741 struct setegid_args {
742 gid_t egid;
743 };
744 #endif
745 /* ARGSUSED */
746 int
747 setegid(struct thread *td, struct setegid_args *uap)
748 {
749 struct proc *p = td->td_proc;
750 struct ucred *newcred, *oldcred;
751 gid_t egid;
752 int error;
753
754 egid = uap->egid;
755 AUDIT_ARG_EGID(egid);
756 newcred = crget();
757 PROC_LOCK(p);
758 oldcred = crcopysafe(p, newcred);
759
760 #ifdef MAC
761 error = mac_cred_check_setegid(oldcred, egid);
762 if (error)
763 goto fail;
764 #endif
765
766 if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */
767 egid != oldcred->cr_svgid && /* allow setegid(saved gid) */
768 (error = priv_check_cred(oldcred, PRIV_CRED_SETEGID, 0)) != 0)
769 goto fail;
770
771 if (oldcred->cr_groups[0] != egid) {
772 change_egid(newcred, egid);
773 setsugid(p);
774 }
775 p->p_ucred = newcred;
776 PROC_UNLOCK(p);
777 crfree(oldcred);
778 return (0);
779
780 fail:
781 PROC_UNLOCK(p);
782 crfree(newcred);
783 return (error);
784 }
785
786 #ifndef _SYS_SYSPROTO_H_
787 struct setgroups_args {
788 u_int gidsetsize;
789 gid_t *gidset;
790 };
791 #endif
792 /* ARGSUSED */
793 int
794 setgroups(struct thread *td, struct setgroups_args *uap)
795 {
796 gid_t *groups = NULL;
797 int error;
798
799 if (uap->gidsetsize > NGROUPS)
800 return (EINVAL);
801 groups = malloc(uap->gidsetsize * sizeof(gid_t), M_TEMP, M_WAITOK);
802 error = copyin(uap->gidset, groups, uap->gidsetsize * sizeof(gid_t));
803 if (error)
804 goto out;
805 error = kern_setgroups(td, uap->gidsetsize, groups);
806 out:
807 free(groups, M_TEMP);
808 return (error);
809 }
810
811 int
812 kern_setgroups(struct thread *td, u_int ngrp, gid_t *groups)
813 {
814 struct proc *p = td->td_proc;
815 struct ucred *newcred, *oldcred;
816 int error;
817
818 if (ngrp > NGROUPS)
819 return (EINVAL);
820 AUDIT_ARG_GROUPSET(groups, ngrp);
821 newcred = crget();
822 crextend(newcred, ngrp);
823 PROC_LOCK(p);
824 oldcred = crcopysafe(p, newcred);
825
826 #ifdef MAC
827 error = mac_cred_check_setgroups(oldcred, ngrp, groups);
828 if (error)
829 goto fail;
830 #endif
831
832 error = priv_check_cred(oldcred, PRIV_CRED_SETGROUPS, 0);
833 if (error)
834 goto fail;
835
836 if (ngrp < 1) {
837 /*
838 * setgroups(0, NULL) is a legitimate way of clearing the
839 * groups vector on non-BSD systems (which generally do not
840 * have the egid in the groups[0]). We risk security holes
841 * when running non-BSD software if we do not do the same.
842 */
843 newcred->cr_ngroups = 1;
844 } else {
845 crsetgroups_locked(newcred, ngrp, groups);
846 }
847 setsugid(p);
848 p->p_ucred = newcred;
849 PROC_UNLOCK(p);
850 crfree(oldcred);
851 return (0);
852
853 fail:
854 PROC_UNLOCK(p);
855 crfree(newcred);
856 return (error);
857 }
858
859 #ifndef _SYS_SYSPROTO_H_
860 struct setreuid_args {
861 uid_t ruid;
862 uid_t euid;
863 };
864 #endif
865 /* ARGSUSED */
866 int
867 setreuid(register struct thread *td, struct setreuid_args *uap)
868 {
869 struct proc *p = td->td_proc;
870 struct ucred *newcred, *oldcred;
871 uid_t euid, ruid;
872 struct uidinfo *euip, *ruip;
873 int error;
874
875 euid = uap->euid;
876 ruid = uap->ruid;
877 AUDIT_ARG_EUID(euid);
878 AUDIT_ARG_RUID(ruid);
879 newcred = crget();
880 euip = uifind(euid);
881 ruip = uifind(ruid);
882 PROC_LOCK(p);
883 oldcred = crcopysafe(p, newcred);
884
885 #ifdef MAC
886 error = mac_cred_check_setreuid(oldcred, ruid, euid);
887 if (error)
888 goto fail;
889 #endif
890
891 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid &&
892 ruid != oldcred->cr_svuid) ||
893 (euid != (uid_t)-1 && euid != oldcred->cr_uid &&
894 euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) &&
895 (error = priv_check_cred(oldcred, PRIV_CRED_SETREUID, 0)) != 0)
896 goto fail;
897
898 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
899 change_euid(newcred, euip);
900 setsugid(p);
901 }
902 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
903 change_ruid(newcred, ruip);
904 setsugid(p);
905 }
906 if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) &&
907 newcred->cr_svuid != newcred->cr_uid) {
908 change_svuid(newcred, newcred->cr_uid);
909 setsugid(p);
910 }
911 p->p_ucred = newcred;
912 PROC_UNLOCK(p);
913 uifree(ruip);
914 uifree(euip);
915 crfree(oldcred);
916 return (0);
917
918 fail:
919 PROC_UNLOCK(p);
920 uifree(ruip);
921 uifree(euip);
922 crfree(newcred);
923 return (error);
924 }
925
926 #ifndef _SYS_SYSPROTO_H_
927 struct setregid_args {
928 gid_t rgid;
929 gid_t egid;
930 };
931 #endif
932 /* ARGSUSED */
933 int
934 setregid(register struct thread *td, struct setregid_args *uap)
935 {
936 struct proc *p = td->td_proc;
937 struct ucred *newcred, *oldcred;
938 gid_t egid, rgid;
939 int error;
940
941 egid = uap->egid;
942 rgid = uap->rgid;
943 AUDIT_ARG_EGID(egid);
944 AUDIT_ARG_RGID(rgid);
945 newcred = crget();
946 PROC_LOCK(p);
947 oldcred = crcopysafe(p, newcred);
948
949 #ifdef MAC
950 error = mac_cred_check_setregid(oldcred, rgid, egid);
951 if (error)
952 goto fail;
953 #endif
954
955 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid &&
956 rgid != oldcred->cr_svgid) ||
957 (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] &&
958 egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) &&
959 (error = priv_check_cred(oldcred, PRIV_CRED_SETREGID, 0)) != 0)
960 goto fail;
961
962 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) {
963 change_egid(newcred, egid);
964 setsugid(p);
965 }
966 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) {
967 change_rgid(newcred, rgid);
968 setsugid(p);
969 }
970 if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) &&
971 newcred->cr_svgid != newcred->cr_groups[0]) {
972 change_svgid(newcred, newcred->cr_groups[0]);
973 setsugid(p);
974 }
975 p->p_ucred = newcred;
976 PROC_UNLOCK(p);
977 crfree(oldcred);
978 return (0);
979
980 fail:
981 PROC_UNLOCK(p);
982 crfree(newcred);
983 return (error);
984 }
985
986 /*
987 * setresuid(ruid, euid, suid) is like setreuid except control over the saved
988 * uid is explicit.
989 */
990 #ifndef _SYS_SYSPROTO_H_
991 struct setresuid_args {
992 uid_t ruid;
993 uid_t euid;
994 uid_t suid;
995 };
996 #endif
997 /* ARGSUSED */
998 int
999 setresuid(register struct thread *td, struct setresuid_args *uap)
1000 {
1001 struct proc *p = td->td_proc;
1002 struct ucred *newcred, *oldcred;
1003 uid_t euid, ruid, suid;
1004 struct uidinfo *euip, *ruip;
1005 int error;
1006
1007 euid = uap->euid;
1008 ruid = uap->ruid;
1009 suid = uap->suid;
1010 AUDIT_ARG_EUID(euid);
1011 AUDIT_ARG_RUID(ruid);
1012 AUDIT_ARG_SUID(suid);
1013 newcred = crget();
1014 euip = uifind(euid);
1015 ruip = uifind(ruid);
1016 PROC_LOCK(p);
1017 oldcred = crcopysafe(p, newcred);
1018
1019 #ifdef MAC
1020 error = mac_cred_check_setresuid(oldcred, ruid, euid, suid);
1021 if (error)
1022 goto fail;
1023 #endif
1024
1025 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid &&
1026 ruid != oldcred->cr_svuid &&
1027 ruid != oldcred->cr_uid) ||
1028 (euid != (uid_t)-1 && euid != oldcred->cr_ruid &&
1029 euid != oldcred->cr_svuid &&
1030 euid != oldcred->cr_uid) ||
1031 (suid != (uid_t)-1 && suid != oldcred->cr_ruid &&
1032 suid != oldcred->cr_svuid &&
1033 suid != oldcred->cr_uid)) &&
1034 (error = priv_check_cred(oldcred, PRIV_CRED_SETRESUID, 0)) != 0)
1035 goto fail;
1036
1037 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) {
1038 change_euid(newcred, euip);
1039 setsugid(p);
1040 }
1041 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) {
1042 change_ruid(newcred, ruip);
1043 setsugid(p);
1044 }
1045 if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) {
1046 change_svuid(newcred, suid);
1047 setsugid(p);
1048 }
1049 p->p_ucred = newcred;
1050 PROC_UNLOCK(p);
1051 uifree(ruip);
1052 uifree(euip);
1053 crfree(oldcred);
1054 return (0);
1055
1056 fail:
1057 PROC_UNLOCK(p);
1058 uifree(ruip);
1059 uifree(euip);
1060 crfree(newcred);
1061 return (error);
1062
1063 }
1064
1065 /*
1066 * setresgid(rgid, egid, sgid) is like setregid except control over the saved
1067 * gid is explicit.
1068 */
1069 #ifndef _SYS_SYSPROTO_H_
1070 struct setresgid_args {
1071 gid_t rgid;
1072 gid_t egid;
1073 gid_t sgid;
1074 };
1075 #endif
1076 /* ARGSUSED */
1077 int
1078 setresgid(register struct thread *td, struct setresgid_args *uap)
1079 {
1080 struct proc *p = td->td_proc;
1081 struct ucred *newcred, *oldcred;
1082 gid_t egid, rgid, sgid;
1083 int error;
1084
1085 egid = uap->egid;
1086 rgid = uap->rgid;
1087 sgid = uap->sgid;
1088 AUDIT_ARG_EGID(egid);
1089 AUDIT_ARG_RGID(rgid);
1090 AUDIT_ARG_SGID(sgid);
1091 newcred = crget();
1092 PROC_LOCK(p);
1093 oldcred = crcopysafe(p, newcred);
1094
1095 #ifdef MAC
1096 error = mac_cred_check_setresgid(oldcred, rgid, egid, sgid);
1097 if (error)
1098 goto fail;
1099 #endif
1100
1101 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid &&
1102 rgid != oldcred->cr_svgid &&
1103 rgid != oldcred->cr_groups[0]) ||
1104 (egid != (gid_t)-1 && egid != oldcred->cr_rgid &&
1105 egid != oldcred->cr_svgid &&
1106 egid != oldcred->cr_groups[0]) ||
1107 (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid &&
1108 sgid != oldcred->cr_svgid &&
1109 sgid != oldcred->cr_groups[0])) &&
1110 (error = priv_check_cred(oldcred, PRIV_CRED_SETRESGID, 0)) != 0)
1111 goto fail;
1112
1113 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) {
1114 change_egid(newcred, egid);
1115 setsugid(p);
1116 }
1117 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) {
1118 change_rgid(newcred, rgid);
1119 setsugid(p);
1120 }
1121 if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) {
1122 change_svgid(newcred, sgid);
1123 setsugid(p);
1124 }
1125 p->p_ucred = newcred;
1126 PROC_UNLOCK(p);
1127 crfree(oldcred);
1128 return (0);
1129
1130 fail:
1131 PROC_UNLOCK(p);
1132 crfree(newcred);
1133 return (error);
1134 }
1135
1136 #ifndef _SYS_SYSPROTO_H_
1137 struct getresuid_args {
1138 uid_t *ruid;
1139 uid_t *euid;
1140 uid_t *suid;
1141 };
1142 #endif
1143 /* ARGSUSED */
1144 int
1145 getresuid(register struct thread *td, struct getresuid_args *uap)
1146 {
1147 struct ucred *cred;
1148 int error1 = 0, error2 = 0, error3 = 0;
1149
1150 cred = td->td_ucred;
1151 if (uap->ruid)
1152 error1 = copyout(&cred->cr_ruid,
1153 uap->ruid, sizeof(cred->cr_ruid));
1154 if (uap->euid)
1155 error2 = copyout(&cred->cr_uid,
1156 uap->euid, sizeof(cred->cr_uid));
1157 if (uap->suid)
1158 error3 = copyout(&cred->cr_svuid,
1159 uap->suid, sizeof(cred->cr_svuid));
1160 return (error1 ? error1 : error2 ? error2 : error3);
1161 }
1162
1163 #ifndef _SYS_SYSPROTO_H_
1164 struct getresgid_args {
1165 gid_t *rgid;
1166 gid_t *egid;
1167 gid_t *sgid;
1168 };
1169 #endif
1170 /* ARGSUSED */
1171 int
1172 getresgid(register struct thread *td, struct getresgid_args *uap)
1173 {
1174 struct ucred *cred;
1175 int error1 = 0, error2 = 0, error3 = 0;
1176
1177 cred = td->td_ucred;
1178 if (uap->rgid)
1179 error1 = copyout(&cred->cr_rgid,
1180 uap->rgid, sizeof(cred->cr_rgid));
1181 if (uap->egid)
1182 error2 = copyout(&cred->cr_groups[0],
1183 uap->egid, sizeof(cred->cr_groups[0]));
1184 if (uap->sgid)
1185 error3 = copyout(&cred->cr_svgid,
1186 uap->sgid, sizeof(cred->cr_svgid));
1187 return (error1 ? error1 : error2 ? error2 : error3);
1188 }
1189
1190 #ifndef _SYS_SYSPROTO_H_
1191 struct issetugid_args {
1192 int dummy;
1193 };
1194 #endif
1195 /* ARGSUSED */
1196 int
1197 issetugid(register struct thread *td, struct issetugid_args *uap)
1198 {
1199 struct proc *p = td->td_proc;
1200
1201 /*
1202 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time,
1203 * we use P_SUGID because we consider changing the owners as
1204 * "tainting" as well.
1205 * This is significant for procs that start as root and "become"
1206 * a user without an exec - programs cannot know *everything*
1207 * that libc *might* have put in their data segment.
1208 */
1209 PROC_LOCK(p);
1210 td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0;
1211 PROC_UNLOCK(p);
1212 return (0);
1213 }
1214
1215 int
1216 __setugid(struct thread *td, struct __setugid_args *uap)
1217 {
1218 #ifdef REGRESSION
1219 struct proc *p;
1220
1221 p = td->td_proc;
1222 switch (uap->flag) {
1223 case 0:
1224 PROC_LOCK(p);
1225 p->p_flag &= ~P_SUGID;
1226 PROC_UNLOCK(p);
1227 return (0);
1228 case 1:
1229 PROC_LOCK(p);
1230 p->p_flag |= P_SUGID;
1231 PROC_UNLOCK(p);
1232 return (0);
1233 default:
1234 return (EINVAL);
1235 }
1236 #else /* !REGRESSION */
1237
1238 return (ENOSYS);
1239 #endif /* REGRESSION */
1240 }
1241
1242 /*
1243 * Check if gid is a member of the group set.
1244 */
1245 int
1246 groupmember(gid_t gid, struct ucred *cred)
1247 {
1248 int l;
1249 int h;
1250 int m;
1251
1252 if (cred->cr_groups[0] == gid)
1253 return(1);
1254
1255 /*
1256 * If gid was not our primary group, perform a binary search
1257 * of the supplemental groups. This is possible because we
1258 * sort the groups in crsetgroups().
1259 */
1260 l = 1;
1261 h = cred->cr_ngroups;
1262 while (l < h) {
1263 m = l + ((h - l) / 2);
1264 if (cred->cr_groups[m] < gid)
1265 l = m + 1;
1266 else
1267 h = m;
1268 }
1269 if ((l < cred->cr_ngroups) && (cred->cr_groups[l] == gid))
1270 return (1);
1271
1272 return (0);
1273 }
1274
1275 /*
1276 * Test the active securelevel against a given level. securelevel_gt()
1277 * implements (securelevel > level). securelevel_ge() implements
1278 * (securelevel >= level). Note that the logic is inverted -- these
1279 * functions return EPERM on "success" and 0 on "failure".
1280 *
1281 * Due to care taken when setting the securelevel, we know that no jail will
1282 * be less secure that its parent (or the physical system), so it is sufficient
1283 * to test the current jail only.
1284 *
1285 * XXXRW: Possibly since this has to do with privilege, it should move to
1286 * kern_priv.c.
1287 */
1288 int
1289 securelevel_gt(struct ucred *cr, int level)
1290 {
1291
1292 return (cr->cr_prison->pr_securelevel > level ? EPERM : 0);
1293 }
1294
1295 int
1296 securelevel_ge(struct ucred *cr, int level)
1297 {
1298
1299 return (cr->cr_prison->pr_securelevel >= level ? EPERM : 0);
1300 }
1301
1302 /*
1303 * 'see_other_uids' determines whether or not visibility of processes
1304 * and sockets with credentials holding different real uids is possible
1305 * using a variety of system MIBs.
1306 * XXX: data declarations should be together near the beginning of the file.
1307 */
1308 static int see_other_uids = 1;
1309 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW,
1310 &see_other_uids, 0,
1311 "Unprivileged processes may see subjects/objects with different real uid");
1312
1313 /*-
1314 * Determine if u1 "can see" the subject specified by u2, according to the
1315 * 'see_other_uids' policy.
1316 * Returns: 0 for permitted, ESRCH otherwise
1317 * Locks: none
1318 * References: *u1 and *u2 must not change during the call
1319 * u1 may equal u2, in which case only one reference is required
1320 */
1321 static int
1322 cr_seeotheruids(struct ucred *u1, struct ucred *u2)
1323 {
1324
1325 if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) {
1326 if (priv_check_cred(u1, PRIV_SEEOTHERUIDS, 0) != 0)
1327 return (ESRCH);
1328 }
1329 return (0);
1330 }
1331
1332 /*
1333 * 'see_other_gids' determines whether or not visibility of processes
1334 * and sockets with credentials holding different real gids is possible
1335 * using a variety of system MIBs.
1336 * XXX: data declarations should be together near the beginning of the file.
1337 */
1338 static int see_other_gids = 1;
1339 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW,
1340 &see_other_gids, 0,
1341 "Unprivileged processes may see subjects/objects with different real gid");
1342
1343 /*
1344 * Determine if u1 can "see" the subject specified by u2, according to the
1345 * 'see_other_gids' policy.
1346 * Returns: 0 for permitted, ESRCH otherwise
1347 * Locks: none
1348 * References: *u1 and *u2 must not change during the call
1349 * u1 may equal u2, in which case only one reference is required
1350 */
1351 static int
1352 cr_seeothergids(struct ucred *u1, struct ucred *u2)
1353 {
1354 int i, match;
1355
1356 if (!see_other_gids) {
1357 match = 0;
1358 for (i = 0; i < u1->cr_ngroups; i++) {
1359 if (groupmember(u1->cr_groups[i], u2))
1360 match = 1;
1361 if (match)
1362 break;
1363 }
1364 if (!match) {
1365 if (priv_check_cred(u1, PRIV_SEEOTHERGIDS, 0) != 0)
1366 return (ESRCH);
1367 }
1368 }
1369 return (0);
1370 }
1371
1372 /*-
1373 * Determine if u1 "can see" the subject specified by u2.
1374 * Returns: 0 for permitted, an errno value otherwise
1375 * Locks: none
1376 * References: *u1 and *u2 must not change during the call
1377 * u1 may equal u2, in which case only one reference is required
1378 */
1379 int
1380 cr_cansee(struct ucred *u1, struct ucred *u2)
1381 {
1382 int error;
1383
1384 if ((error = prison_check(u1, u2)))
1385 return (error);
1386 #ifdef MAC
1387 if ((error = mac_cred_check_visible(u1, u2)))
1388 return (error);
1389 #endif
1390 if ((error = cr_seeotheruids(u1, u2)))
1391 return (error);
1392 if ((error = cr_seeothergids(u1, u2)))
1393 return (error);
1394 return (0);
1395 }
1396
1397 /*-
1398 * Determine if td "can see" the subject specified by p.
1399 * Returns: 0 for permitted, an errno value otherwise
1400 * Locks: Sufficient locks to protect p->p_ucred must be held. td really
1401 * should be curthread.
1402 * References: td and p must be valid for the lifetime of the call
1403 */
1404 int
1405 p_cansee(struct thread *td, struct proc *p)
1406 {
1407
1408 /* Wrap cr_cansee() for all functionality. */
1409 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1410 PROC_LOCK_ASSERT(p, MA_OWNED);
1411 return (cr_cansee(td->td_ucred, p->p_ucred));
1412 }
1413
1414 /*
1415 * 'conservative_signals' prevents the delivery of a broad class of
1416 * signals by unprivileged processes to processes that have changed their
1417 * credentials since the last invocation of execve(). This can prevent
1418 * the leakage of cached information or retained privileges as a result
1419 * of a common class of signal-related vulnerabilities. However, this
1420 * may interfere with some applications that expect to be able to
1421 * deliver these signals to peer processes after having given up
1422 * privilege.
1423 */
1424 static int conservative_signals = 1;
1425 SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW,
1426 &conservative_signals, 0, "Unprivileged processes prevented from "
1427 "sending certain signals to processes whose credentials have changed");
1428 /*-
1429 * Determine whether cred may deliver the specified signal to proc.
1430 * Returns: 0 for permitted, an errno value otherwise.
1431 * Locks: A lock must be held for proc.
1432 * References: cred and proc must be valid for the lifetime of the call.
1433 */
1434 int
1435 cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
1436 {
1437 int error;
1438
1439 PROC_LOCK_ASSERT(proc, MA_OWNED);
1440 /*
1441 * Jail semantics limit the scope of signalling to proc in the
1442 * same jail as cred, if cred is in jail.
1443 */
1444 error = prison_check(cred, proc->p_ucred);
1445 if (error)
1446 return (error);
1447 #ifdef MAC
1448 if ((error = mac_proc_check_signal(cred, proc, signum)))
1449 return (error);
1450 #endif
1451 if ((error = cr_seeotheruids(cred, proc->p_ucred)))
1452 return (error);
1453 if ((error = cr_seeothergids(cred, proc->p_ucred)))
1454 return (error);
1455
1456 /*
1457 * UNIX signal semantics depend on the status of the P_SUGID
1458 * bit on the target process. If the bit is set, then additional
1459 * restrictions are placed on the set of available signals.
1460 */
1461 if (conservative_signals && (proc->p_flag & P_SUGID)) {
1462 switch (signum) {
1463 case 0:
1464 case SIGKILL:
1465 case SIGINT:
1466 case SIGTERM:
1467 case SIGALRM:
1468 case SIGSTOP:
1469 case SIGTTIN:
1470 case SIGTTOU:
1471 case SIGTSTP:
1472 case SIGHUP:
1473 case SIGUSR1:
1474 case SIGUSR2:
1475 /*
1476 * Generally, permit job and terminal control
1477 * signals.
1478 */
1479 break;
1480 default:
1481 /* Not permitted without privilege. */
1482 error = priv_check_cred(cred, PRIV_SIGNAL_SUGID, 0);
1483 if (error)
1484 return (error);
1485 }
1486 }
1487
1488 /*
1489 * Generally, the target credential's ruid or svuid must match the
1490 * subject credential's ruid or euid.
1491 */
1492 if (cred->cr_ruid != proc->p_ucred->cr_ruid &&
1493 cred->cr_ruid != proc->p_ucred->cr_svuid &&
1494 cred->cr_uid != proc->p_ucred->cr_ruid &&
1495 cred->cr_uid != proc->p_ucred->cr_svuid) {
1496 error = priv_check_cred(cred, PRIV_SIGNAL_DIFFCRED, 0);
1497 if (error)
1498 return (error);
1499 }
1500
1501 return (0);
1502 }
1503
1504 /*-
1505 * Determine whether td may deliver the specified signal to p.
1506 * Returns: 0 for permitted, an errno value otherwise
1507 * Locks: Sufficient locks to protect various components of td and p
1508 * must be held. td must be curthread, and a lock must be
1509 * held for p.
1510 * References: td and p must be valid for the lifetime of the call
1511 */
1512 int
1513 p_cansignal(struct thread *td, struct proc *p, int signum)
1514 {
1515
1516 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1517 PROC_LOCK_ASSERT(p, MA_OWNED);
1518 if (td->td_proc == p)
1519 return (0);
1520
1521 /*
1522 * UNIX signalling semantics require that processes in the same
1523 * session always be able to deliver SIGCONT to one another,
1524 * overriding the remaining protections.
1525 */
1526 /* XXX: This will require an additional lock of some sort. */
1527 if (signum == SIGCONT && td->td_proc->p_session == p->p_session)
1528 return (0);
1529 /*
1530 * Some compat layers use SIGTHR and higher signals for
1531 * communication between different kernel threads of the same
1532 * process, so that they expect that it's always possible to
1533 * deliver them, even for suid applications where cr_cansignal() can
1534 * deny such ability for security consideration. It should be
1535 * pretty safe to do since the only way to create two processes
1536 * with the same p_leader is via rfork(2).
1537 */
1538 if (td->td_proc->p_leader != NULL && signum >= SIGTHR &&
1539 signum < SIGTHR + 4 && td->td_proc->p_leader == p->p_leader)
1540 return (0);
1541
1542 return (cr_cansignal(td->td_ucred, p, signum));
1543 }
1544
1545 /*-
1546 * Determine whether td may reschedule p.
1547 * Returns: 0 for permitted, an errno value otherwise
1548 * Locks: Sufficient locks to protect various components of td and p
1549 * must be held. td must be curthread, and a lock must
1550 * be held for p.
1551 * References: td and p must be valid for the lifetime of the call
1552 */
1553 int
1554 p_cansched(struct thread *td, struct proc *p)
1555 {
1556 int error;
1557
1558 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1559 PROC_LOCK_ASSERT(p, MA_OWNED);
1560 if (td->td_proc == p)
1561 return (0);
1562 if ((error = prison_check(td->td_ucred, p->p_ucred)))
1563 return (error);
1564 #ifdef MAC
1565 if ((error = mac_proc_check_sched(td->td_ucred, p)))
1566 return (error);
1567 #endif
1568 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred)))
1569 return (error);
1570 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred)))
1571 return (error);
1572 if (td->td_ucred->cr_ruid != p->p_ucred->cr_ruid &&
1573 td->td_ucred->cr_uid != p->p_ucred->cr_ruid) {
1574 error = priv_check(td, PRIV_SCHED_DIFFCRED);
1575 if (error)
1576 return (error);
1577 }
1578 return (0);
1579 }
1580
1581 /*
1582 * The 'unprivileged_proc_debug' flag may be used to disable a variety of
1583 * unprivileged inter-process debugging services, including some procfs
1584 * functionality, ptrace(), and ktrace(). In the past, inter-process
1585 * debugging has been involved in a variety of security problems, and sites
1586 * not requiring the service might choose to disable it when hardening
1587 * systems.
1588 *
1589 * XXX: Should modifying and reading this variable require locking?
1590 * XXX: data declarations should be together near the beginning of the file.
1591 */
1592 static int unprivileged_proc_debug = 1;
1593 SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW,
1594 &unprivileged_proc_debug, 0,
1595 "Unprivileged processes may use process debugging facilities");
1596
1597 /*-
1598 * Determine whether td may debug p.
1599 * Returns: 0 for permitted, an errno value otherwise
1600 * Locks: Sufficient locks to protect various components of td and p
1601 * must be held. td must be curthread, and a lock must
1602 * be held for p.
1603 * References: td and p must be valid for the lifetime of the call
1604 */
1605 int
1606 p_candebug(struct thread *td, struct proc *p)
1607 {
1608 int credentialchanged, error, grpsubset, i, uidsubset;
1609
1610 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1611 PROC_LOCK_ASSERT(p, MA_OWNED);
1612 if (!unprivileged_proc_debug) {
1613 error = priv_check(td, PRIV_DEBUG_UNPRIV);
1614 if (error)
1615 return (error);
1616 }
1617 if (td->td_proc == p)
1618 return (0);
1619 if ((error = prison_check(td->td_ucred, p->p_ucred)))
1620 return (error);
1621 #ifdef MAC
1622 if ((error = mac_proc_check_debug(td->td_ucred, p)))
1623 return (error);
1624 #endif
1625 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred)))
1626 return (error);
1627 if ((error = cr_seeothergids(td->td_ucred, p->p_ucred)))
1628 return (error);
1629
1630 /*
1631 * Is p's group set a subset of td's effective group set? This
1632 * includes p's egid, group access list, rgid, and svgid.
1633 */
1634 grpsubset = 1;
1635 for (i = 0; i < p->p_ucred->cr_ngroups; i++) {
1636 if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) {
1637 grpsubset = 0;
1638 break;
1639 }
1640 }
1641 grpsubset = grpsubset &&
1642 groupmember(p->p_ucred->cr_rgid, td->td_ucred) &&
1643 groupmember(p->p_ucred->cr_svgid, td->td_ucred);
1644
1645 /*
1646 * Are the uids present in p's credential equal to td's
1647 * effective uid? This includes p's euid, svuid, and ruid.
1648 */
1649 uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid &&
1650 td->td_ucred->cr_uid == p->p_ucred->cr_svuid &&
1651 td->td_ucred->cr_uid == p->p_ucred->cr_ruid);
1652
1653 /*
1654 * Has the credential of the process changed since the last exec()?
1655 */
1656 credentialchanged = (p->p_flag & P_SUGID);
1657
1658 /*
1659 * If p's gids aren't a subset, or the uids aren't a subset,
1660 * or the credential has changed, require appropriate privilege
1661 * for td to debug p.
1662 */
1663 if (!grpsubset || !uidsubset) {
1664 error = priv_check(td, PRIV_DEBUG_DIFFCRED);
1665 if (error)
1666 return (error);
1667 }
1668
1669 if (credentialchanged) {
1670 error = priv_check(td, PRIV_DEBUG_SUGID);
1671 if (error)
1672 return (error);
1673 }
1674
1675 /* Can't trace init when securelevel > 0. */
1676 if (p == initproc) {
1677 error = securelevel_gt(td->td_ucred, 0);
1678 if (error)
1679 return (error);
1680 }
1681
1682 /*
1683 * Can't trace a process that's currently exec'ing.
1684 *
1685 * XXX: Note, this is not a security policy decision, it's a
1686 * basic correctness/functionality decision. Therefore, this check
1687 * should be moved to the caller's of p_candebug().
1688 */
1689 if ((p->p_flag & P_INEXEC) != 0)
1690 return (EBUSY);
1691
1692 return (0);
1693 }
1694
1695 /*-
1696 * Determine whether the subject represented by cred can "see" a socket.
1697 * Returns: 0 for permitted, ENOENT otherwise.
1698 */
1699 int
1700 cr_canseesocket(struct ucred *cred, struct socket *so)
1701 {
1702 int error;
1703
1704 error = prison_check(cred, so->so_cred);
1705 if (error)
1706 return (ENOENT);
1707 #ifdef MAC
1708 error = mac_socket_check_visible(cred, so);
1709 if (error)
1710 return (error);
1711 #endif
1712 if (cr_seeotheruids(cred, so->so_cred))
1713 return (ENOENT);
1714 if (cr_seeothergids(cred, so->so_cred))
1715 return (ENOENT);
1716
1717 return (0);
1718 }
1719
1720 #if defined(INET) || defined(INET6)
1721 /*-
1722 * Determine whether the subject represented by cred can "see" a socket.
1723 * Returns: 0 for permitted, ENOENT otherwise.
1724 */
1725 int
1726 cr_canseeinpcb(struct ucred *cred, struct inpcb *inp)
1727 {
1728 int error;
1729
1730 error = prison_check(cred, inp->inp_cred);
1731 if (error)
1732 return (ENOENT);
1733 #ifdef MAC
1734 INP_LOCK_ASSERT(inp);
1735 error = mac_inpcb_check_visible(cred, inp);
1736 if (error)
1737 return (error);
1738 #endif
1739 if (cr_seeotheruids(cred, inp->inp_cred))
1740 return (ENOENT);
1741 if (cr_seeothergids(cred, inp->inp_cred))
1742 return (ENOENT);
1743
1744 return (0);
1745 }
1746 #endif
1747
1748 /*-
1749 * Determine whether td can wait for the exit of p.
1750 * Returns: 0 for permitted, an errno value otherwise
1751 * Locks: Sufficient locks to protect various components of td and p
1752 * must be held. td must be curthread, and a lock must
1753 * be held for p.
1754 * References: td and p must be valid for the lifetime of the call
1755
1756 */
1757 int
1758 p_canwait(struct thread *td, struct proc *p)
1759 {
1760 int error;
1761
1762 KASSERT(td == curthread, ("%s: td not curthread", __func__));
1763 PROC_LOCK_ASSERT(p, MA_OWNED);
1764 if ((error = prison_check(td->td_ucred, p->p_ucred)))
1765 return (error);
1766 #ifdef MAC
1767 if ((error = mac_proc_check_wait(td->td_ucred, p)))
1768 return (error);
1769 #endif
1770 #if 0
1771 /* XXXMAC: This could have odd effects on some shells. */
1772 if ((error = cr_seeotheruids(td->td_ucred, p->p_ucred)))
1773 return (error);
1774 #endif
1775
1776 return (0);
1777 }
1778
1779 /*
1780 * Allocate a zeroed cred structure.
1781 */
1782 struct ucred *
1783 crget(void)
1784 {
1785 register struct ucred *cr;
1786
1787 cr = malloc(sizeof(*cr), M_CRED, M_WAITOK | M_ZERO);
1788 refcount_init(&cr->cr_ref, 1);
1789 #ifdef AUDIT
1790 audit_cred_init(cr);
1791 #endif
1792 #ifdef MAC
1793 mac_cred_init(cr);
1794 #endif
1795 crextend(cr, XU_NGROUPS);
1796 return (cr);
1797 }
1798
1799 /*
1800 * Claim another reference to a ucred structure.
1801 */
1802 struct ucred *
1803 crhold(struct ucred *cr)
1804 {
1805
1806 refcount_acquire(&cr->cr_ref);
1807 return (cr);
1808 }
1809
1810 /*
1811 * Free a cred structure. Throws away space when ref count gets to 0.
1812 */
1813 void
1814 crfree(struct ucred *cr)
1815 {
1816
1817 KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref));
1818 KASSERT(cr->cr_ref != 0xdeadc0de, ("dangling reference to ucred"));
1819 if (refcount_release(&cr->cr_ref)) {
1820 /*
1821 * Some callers of crget(), such as nfs_statfs(),
1822 * allocate a temporary credential, but don't
1823 * allocate a uidinfo structure.
1824 */
1825 if (cr->cr_uidinfo != NULL)
1826 uifree(cr->cr_uidinfo);
1827 if (cr->cr_ruidinfo != NULL)
1828 uifree(cr->cr_ruidinfo);
1829 /*
1830 * Free a prison, if any.
1831 */
1832 if (cr->cr_prison != NULL)
1833 prison_free(cr->cr_prison);
1834 #ifdef AUDIT
1835 audit_cred_destroy(cr);
1836 #endif
1837 #ifdef MAC
1838 mac_cred_destroy(cr);
1839 #endif
1840 free(cr->cr_groups, M_CRED);
1841 free(cr, M_CRED);
1842 }
1843 }
1844
1845 /*
1846 * Check to see if this ucred is shared.
1847 */
1848 int
1849 crshared(struct ucred *cr)
1850 {
1851
1852 return (cr->cr_ref > 1);
1853 }
1854
1855 /*
1856 * Copy a ucred's contents from a template. Does not block.
1857 */
1858 void
1859 crcopy(struct ucred *dest, struct ucred *src)
1860 {
1861
1862 KASSERT(crshared(dest) == 0, ("crcopy of shared ucred"));
1863 bcopy(&src->cr_startcopy, &dest->cr_startcopy,
1864 (unsigned)((caddr_t)&src->cr_endcopy -
1865 (caddr_t)&src->cr_startcopy));
1866 crsetgroups(dest, src->cr_ngroups, src->cr_groups);
1867 uihold(dest->cr_uidinfo);
1868 uihold(dest->cr_ruidinfo);
1869 prison_hold(dest->cr_prison);
1870 #ifdef AUDIT
1871 audit_cred_copy(src, dest);
1872 #endif
1873 #ifdef MAC
1874 mac_cred_copy(src, dest);
1875 #endif
1876 }
1877
1878 /*
1879 * Dup cred struct to a new held one.
1880 */
1881 struct ucred *
1882 crdup(struct ucred *cr)
1883 {
1884 struct ucred *newcr;
1885
1886 newcr = crget();
1887 crcopy(newcr, cr);
1888 return (newcr);
1889 }
1890
1891 /*
1892 * Fill in a struct xucred based on a struct ucred.
1893 */
1894 void
1895 cru2x(struct ucred *cr, struct xucred *xcr)
1896 {
1897 int ngroups;
1898
1899 bzero(xcr, sizeof(*xcr));
1900 xcr->cr_version = XUCRED_VERSION;
1901 xcr->cr_uid = cr->cr_uid;
1902
1903 ngroups = MIN(cr->cr_ngroups, XU_NGROUPS);
1904 xcr->cr_ngroups = ngroups;
1905 bcopy(cr->cr_groups, xcr->cr_groups,
1906 ngroups * sizeof(*cr->cr_groups));
1907 }
1908
1909 /*
1910 * small routine to swap a thread's current ucred for the correct one taken
1911 * from the process.
1912 */
1913 void
1914 cred_update_thread(struct thread *td)
1915 {
1916 struct proc *p;
1917 struct ucred *cred;
1918
1919 p = td->td_proc;
1920 cred = td->td_ucred;
1921 PROC_LOCK(p);
1922 td->td_ucred = crhold(p->p_ucred);
1923 PROC_UNLOCK(p);
1924 if (cred != NULL)
1925 crfree(cred);
1926 }
1927
1928 struct ucred *
1929 crcopysafe(struct proc *p, struct ucred *cr)
1930 {
1931 struct ucred *oldcred;
1932 int groups;
1933
1934 PROC_LOCK_ASSERT(p, MA_OWNED);
1935
1936 oldcred = p->p_ucred;
1937 while (cr->cr_agroups < oldcred->cr_agroups) {
1938 groups = oldcred->cr_agroups;
1939 PROC_UNLOCK(p);
1940 crextend(cr, groups);
1941 PROC_LOCK(p);
1942 oldcred = p->p_ucred;
1943 }
1944 crcopy(cr, oldcred);
1945
1946 return (oldcred);
1947 }
1948
1949 /*
1950 * Extend the passed in credential to hold n items.
1951 */
1952 static void
1953 crextend(struct ucred *cr, int n)
1954 {
1955 int cnt;
1956
1957 /* Truncate? */
1958 if (n <= cr->cr_agroups)
1959 return;
1960
1961 /*
1962 * We extend by 2 each time since we're using a power of two
1963 * allocator until we need enough groups to fill a page.
1964 * Once we're allocating multiple pages, only allocate as many
1965 * as we actually need. The case of processes needing a
1966 * non-power of two number of pages seems more likely than
1967 * a real world process that adds thousands of groups one at a
1968 * time.
1969 */
1970 if ( n < PAGE_SIZE / sizeof(gid_t) ) {
1971 if (cr->cr_agroups == 0)
1972 cnt = MINALLOCSIZE / sizeof(gid_t);
1973 else
1974 cnt = cr->cr_agroups * 2;
1975
1976 while (cnt < n)
1977 cnt *= 2;
1978 } else
1979 cnt = roundup2(n, PAGE_SIZE / sizeof(gid_t));
1980
1981 /* Free the old array. */
1982 if (cr->cr_groups)
1983 free(cr->cr_groups, M_CRED);
1984
1985 cr->cr_groups = malloc(cnt * sizeof(gid_t), M_CRED, M_WAITOK | M_ZERO);
1986 cr->cr_agroups = cnt;
1987 }
1988
1989 /*
1990 * Copy groups in to a credential, preserving any necessary invariants.
1991 * Currently this includes the sorting of all supplemental gids.
1992 * crextend() must have been called before hand to ensure sufficient
1993 * space is available.
1994 */
1995 static void
1996 crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups)
1997 {
1998 int i;
1999 int j;
2000 gid_t g;
2001
2002 KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small"));
2003
2004 bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t));
2005 cr->cr_ngroups = ngrp;
2006
2007 /*
2008 * Sort all groups except cr_groups[0] to allow groupmember to
2009 * perform a binary search.
2010 *
2011 * XXX: If large numbers of groups become common this should
2012 * be replaced with shell sort like linux uses or possibly
2013 * heap sort.
2014 */
2015 for (i = 2; i < ngrp; i++) {
2016 g = cr->cr_groups[i];
2017 for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--)
2018 cr->cr_groups[j + 1] = cr->cr_groups[j];
2019 cr->cr_groups[j + 1] = g;
2020 }
2021 }
2022
2023 /*
2024 * Copy groups in to a credential after expanding it if required.
2025 * Truncate the list to NGROUPS if it is too large.
2026 */
2027 void
2028 crsetgroups(struct ucred *cr, int ngrp, gid_t *groups)
2029 {
2030
2031 if (ngrp > NGROUPS)
2032 ngrp = NGROUPS;
2033
2034 crextend(cr, ngrp);
2035 crsetgroups_locked(cr, ngrp, groups);
2036 }
2037
2038 /*
2039 * Get login name, if available.
2040 */
2041 #ifndef _SYS_SYSPROTO_H_
2042 struct getlogin_args {
2043 char *namebuf;
2044 u_int namelen;
2045 };
2046 #endif
2047 /* ARGSUSED */
2048 int
2049 getlogin(struct thread *td, struct getlogin_args *uap)
2050 {
2051 int error;
2052 char login[MAXLOGNAME];
2053 struct proc *p = td->td_proc;
2054
2055 if (uap->namelen > MAXLOGNAME)
2056 uap->namelen = MAXLOGNAME;
2057 PROC_LOCK(p);
2058 SESS_LOCK(p->p_session);
2059 bcopy(p->p_session->s_login, login, uap->namelen);
2060 SESS_UNLOCK(p->p_session);
2061 PROC_UNLOCK(p);
2062 error = copyout(login, uap->namebuf, uap->namelen);
2063 return(error);
2064 }
2065
2066 /*
2067 * Set login name.
2068 */
2069 #ifndef _SYS_SYSPROTO_H_
2070 struct setlogin_args {
2071 char *namebuf;
2072 };
2073 #endif
2074 /* ARGSUSED */
2075 int
2076 setlogin(struct thread *td, struct setlogin_args *uap)
2077 {
2078 struct proc *p = td->td_proc;
2079 int error;
2080 char logintmp[MAXLOGNAME];
2081
2082 error = priv_check(td, PRIV_PROC_SETLOGIN);
2083 if (error)
2084 return (error);
2085 error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL);
2086 if (error == ENAMETOOLONG)
2087 error = EINVAL;
2088 else if (!error) {
2089 PROC_LOCK(p);
2090 SESS_LOCK(p->p_session);
2091 (void) memcpy(p->p_session->s_login, logintmp,
2092 sizeof(logintmp));
2093 SESS_UNLOCK(p->p_session);
2094 PROC_UNLOCK(p);
2095 }
2096 return (error);
2097 }
2098
2099 void
2100 setsugid(struct proc *p)
2101 {
2102
2103 PROC_LOCK_ASSERT(p, MA_OWNED);
2104 p->p_flag |= P_SUGID;
2105 if (!(p->p_pfsflags & PF_ISUGID))
2106 p->p_stops = 0;
2107 }
2108
2109 /*-
2110 * Change a process's effective uid.
2111 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified.
2112 * References: newcred must be an exclusive credential reference for the
2113 * duration of the call.
2114 */
2115 void
2116 change_euid(struct ucred *newcred, struct uidinfo *euip)
2117 {
2118
2119 newcred->cr_uid = euip->ui_uid;
2120 uihold(euip);
2121 uifree(newcred->cr_uidinfo);
2122 newcred->cr_uidinfo = euip;
2123 }
2124
2125 /*-
2126 * Change a process's effective gid.
2127 * Side effects: newcred->cr_gid will be modified.
2128 * References: newcred must be an exclusive credential reference for the
2129 * duration of the call.
2130 */
2131 void
2132 change_egid(struct ucred *newcred, gid_t egid)
2133 {
2134
2135 newcred->cr_groups[0] = egid;
2136 }
2137
2138 /*-
2139 * Change a process's real uid.
2140 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo
2141 * will be updated, and the old and new cr_ruidinfo proc
2142 * counts will be updated.
2143 * References: newcred must be an exclusive credential reference for the
2144 * duration of the call.
2145 */
2146 void
2147 change_ruid(struct ucred *newcred, struct uidinfo *ruip)
2148 {
2149
2150 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0);
2151 newcred->cr_ruid = ruip->ui_uid;
2152 uihold(ruip);
2153 uifree(newcred->cr_ruidinfo);
2154 newcred->cr_ruidinfo = ruip;
2155 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0);
2156 }
2157
2158 /*-
2159 * Change a process's real gid.
2160 * Side effects: newcred->cr_rgid will be updated.
2161 * References: newcred must be an exclusive credential reference for the
2162 * duration of the call.
2163 */
2164 void
2165 change_rgid(struct ucred *newcred, gid_t rgid)
2166 {
2167
2168 newcred->cr_rgid = rgid;
2169 }
2170
2171 /*-
2172 * Change a process's saved uid.
2173 * Side effects: newcred->cr_svuid will be updated.
2174 * References: newcred must be an exclusive credential reference for the
2175 * duration of the call.
2176 */
2177 void
2178 change_svuid(struct ucred *newcred, uid_t svuid)
2179 {
2180
2181 newcred->cr_svuid = svuid;
2182 }
2183
2184 /*-
2185 * Change a process's saved gid.
2186 * Side effects: newcred->cr_svgid will be updated.
2187 * References: newcred must be an exclusive credential reference for the
2188 * duration of the call.
2189 */
2190 void
2191 change_svgid(struct ucred *newcred, gid_t svgid)
2192 {
2193
2194 newcred->cr_svgid = svgid;
2195 }
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