1/*-
2 * Copyright (c) 1999-2002 Robert N. M. Watson
3 * Copyright (c) 2001 Ilmar S. Habibulin
4 * Copyright (c) 2001-2003 Networks Associates Technology, Inc.
5 * Copyright (c) 2005 Samy Al Bahra
6 * All rights reserved.
7 *
8 * This software was developed by Robert Watson and Ilmar Habibulin for the
9 * TrustedBSD Project.
10 *
11 * This software was developed for the FreeBSD Project in part by Network
12 * Associates Laboratories, the Security Research Division of Network
13 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
14 * as part of the DARPA CHATS research program.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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
38#include <sys/cdefs.h>
|
39__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 151115 2005-10-09 02:37:27Z csjp $");
|
| 39__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 156225 2006-03-02 22:13:28Z tegge $"); |
40
41#include "opt_mac.h"
42
43#include <sys/param.h>
44#include <sys/condvar.h>
45#include <sys/imgact.h>
46#include <sys/kernel.h>
47#include <sys/lock.h>
48#include <sys/malloc.h>
49#include <sys/mutex.h>
50#include <sys/mac.h>
51#include <sys/proc.h>
52#include <sys/sbuf.h>
53#include <sys/systm.h>
54#include <sys/vnode.h>
55#include <sys/mount.h>
56#include <sys/file.h>
57#include <sys/namei.h>
58#include <sys/sysctl.h>
59
60#include <vm/vm.h>
61#include <vm/pmap.h>
62#include <vm/vm_map.h>
63#include <vm/vm_object.h>
64
65#include <sys/mac_policy.h>
66
67#include <security/mac/mac_internal.h>
68
69int mac_enforce_process = 1;
70SYSCTL_INT(_security_mac, OID_AUTO, enforce_process, CTLFLAG_RW,
71 &mac_enforce_process, 0, "Enforce MAC policy on inter-process operations");
72TUNABLE_INT("security.mac.enforce_process", &mac_enforce_process);
73
74int mac_enforce_vm = 1;
75SYSCTL_INT(_security_mac, OID_AUTO, enforce_vm, CTLFLAG_RW,
76 &mac_enforce_vm, 0, "Enforce MAC policy on vm operations");
77TUNABLE_INT("security.mac.enforce_vm", &mac_enforce_vm);
78
79static int mac_mmap_revocation = 1;
80SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW,
81 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject "
82 "relabel");
83
84static int mac_mmap_revocation_via_cow = 0;
85SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW,
86 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via "
87 "copy-on-write semantics, or by removing all write access");
88
89static int mac_enforce_suid = 1;
90SYSCTL_INT(_security_mac, OID_AUTO, enforce_suid, CTLFLAG_RW,
91 &mac_enforce_suid, 0, "Enforce MAC policy on suid/sgid operations");
92TUNABLE_INT("security.mac.enforce_suid", &mac_enforce_suid);
93
94#ifdef MAC_DEBUG
95static unsigned int nmaccreds, nmacprocs;
96SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, creds, CTLFLAG_RD,
97 &nmaccreds, 0, "number of ucreds in use");
98SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, procs, CTLFLAG_RD,
99 &nmacprocs, 0, "number of procs in use");
100#endif
101
102static void mac_cred_mmapped_drop_perms_recurse(struct thread *td,
103 struct ucred *cred, struct vm_map *map);
104
105struct label *
106mac_cred_label_alloc(void)
107{
108 struct label *label;
109
110 label = mac_labelzone_alloc(M_WAITOK);
111 MAC_PERFORM(init_cred_label, label);
112 MAC_DEBUG_COUNTER_INC(&nmaccreds);
113 return (label);
114}
115
116void
117mac_init_cred(struct ucred *cred)
118{
119
120 cred->cr_label = mac_cred_label_alloc();
121}
122
123static struct label *
124mac_proc_label_alloc(void)
125{
126 struct label *label;
127
128 label = mac_labelzone_alloc(M_WAITOK);
129 MAC_PERFORM(init_proc_label, label);
130 MAC_DEBUG_COUNTER_INC(&nmacprocs);
131 return (label);
132}
133
134void
135mac_init_proc(struct proc *p)
136{
137
138 p->p_label = mac_proc_label_alloc();
139}
140
141void
142mac_cred_label_free(struct label *label)
143{
144
145 MAC_PERFORM(destroy_cred_label, label);
146 mac_labelzone_free(label);
147 MAC_DEBUG_COUNTER_DEC(&nmaccreds);
148}
149
150void
151mac_destroy_cred(struct ucred *cred)
152{
153
154 mac_cred_label_free(cred->cr_label);
155 cred->cr_label = NULL;
156}
157
158static void
159mac_proc_label_free(struct label *label)
160{
161
162 MAC_PERFORM(destroy_proc_label, label);
163 mac_labelzone_free(label);
164 MAC_DEBUG_COUNTER_DEC(&nmacprocs);
165}
166
167void
168mac_destroy_proc(struct proc *p)
169{
170
171 mac_proc_label_free(p->p_label);
172 p->p_label = NULL;
173}
174
175int
176mac_externalize_cred_label(struct label *label, char *elements,
177 char *outbuf, size_t outbuflen)
178{
179 int error;
180
181 MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen);
182
183 return (error);
184}
185
186int
187mac_internalize_cred_label(struct label *label, char *string)
188{
189 int error;
190
191 MAC_INTERNALIZE(cred, label, string);
192
193 return (error);
194}
195
196/*
197 * Initialize MAC label for the first kernel process, from which other
198 * kernel processes and threads are spawned.
199 */
200void
201mac_create_proc0(struct ucred *cred)
202{
203
204 MAC_PERFORM(create_proc0, cred);
205}
206
207/*
208 * Initialize MAC label for the first userland process, from which other
209 * userland processes and threads are spawned.
210 */
211void
212mac_create_proc1(struct ucred *cred)
213{
214
215 MAC_PERFORM(create_proc1, cred);
216}
217
218void
219mac_thread_userret(struct thread *td)
220{
221
222 MAC_PERFORM(thread_userret, td);
223}
224
225/*
226 * When a new process is created, its label must be initialized. Generally,
227 * this involves inheritence from the parent process, modulo possible
228 * deltas. This function allows that processing to take place.
229 */
230void
231mac_copy_cred(struct ucred *src, struct ucred *dest)
232{
233
234 MAC_PERFORM(copy_cred_label, src->cr_label, dest->cr_label);
235}
236
237int
238mac_execve_enter(struct image_params *imgp, struct mac *mac_p)
239{
240 struct label *label;
241 struct mac mac;
242 char *buffer;
243 int error;
244
245 if (mac_p == NULL)
246 return (0);
247
248 error = copyin(mac_p, &mac, sizeof(mac));
249 if (error)
250 return (error);
251
252 error = mac_check_structmac_consistent(&mac);
253 if (error)
254 return (error);
255
256 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK);
257 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL);
258 if (error) {
259 free(buffer, M_MACTEMP);
260 return (error);
261 }
262
263 label = mac_cred_label_alloc();
264 error = mac_internalize_cred_label(label, buffer);
265 free(buffer, M_MACTEMP);
266 if (error) {
267 mac_cred_label_free(label);
268 return (error);
269 }
270 imgp->execlabel = label;
271 return (0);
272}
273
274void
275mac_execve_exit(struct image_params *imgp)
276{
277 if (imgp->execlabel != NULL) {
278 mac_cred_label_free(imgp->execlabel);
279 imgp->execlabel = NULL;
280 }
281}
282
283/*
284 * When relabeling a process, call out to the policies for the maximum
285 * permission allowed for each object type we know about in its
286 * memory space, and revoke access (in the least surprising ways we
287 * know) when necessary. The process lock is not held here.
288 */
289void
290mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred)
291{
292
293 /* XXX freeze all other threads */
294 mac_cred_mmapped_drop_perms_recurse(td, cred,
295 &td->td_proc->p_vmspace->vm_map);
296 /* XXX allow other threads to continue */
297}
298
299static __inline const char *
300prot2str(vm_prot_t prot)
301{
302
303 switch (prot & VM_PROT_ALL) {
304 case VM_PROT_READ:
305 return ("r--");
306 case VM_PROT_READ | VM_PROT_WRITE:
307 return ("rw-");
308 case VM_PROT_READ | VM_PROT_EXECUTE:
309 return ("r-x");
310 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE:
311 return ("rwx");
312 case VM_PROT_WRITE:
313 return ("-w-");
314 case VM_PROT_EXECUTE:
315 return ("--x");
316 case VM_PROT_WRITE | VM_PROT_EXECUTE:
317 return ("-wx");
318 default:
319 return ("---");
320 }
321}
322
323static void
324mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
325 struct vm_map *map)
326{
327 struct vm_map_entry *vme;
328 int vfslocked, result;
329 vm_prot_t revokeperms;
330 vm_object_t backing_object, object;
331 vm_ooffset_t offset;
332 struct vnode *vp;
|
| 333 struct mount *mp; |
334
335 if (!mac_mmap_revocation)
336 return;
337
338 vm_map_lock_read(map);
339 for (vme = map->header.next; vme != &map->header; vme = vme->next) {
340 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
341 mac_cred_mmapped_drop_perms_recurse(td, cred,
342 vme->object.sub_map);
343 continue;
344 }
345 /*
346 * Skip over entries that obviously are not shared.
347 */
348 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) ||
349 !vme->max_protection)
350 continue;
351 /*
352 * Drill down to the deepest backing object.
353 */
354 offset = vme->offset;
355 object = vme->object.vm_object;
356 if (object == NULL)
357 continue;
358 VM_OBJECT_LOCK(object);
359 while ((backing_object = object->backing_object) != NULL) {
360 VM_OBJECT_LOCK(backing_object);
361 offset += object->backing_object_offset;
362 VM_OBJECT_UNLOCK(object);
363 object = backing_object;
364 }
365 VM_OBJECT_UNLOCK(object);
366 /*
367 * At the moment, vm_maps and objects aren't considered
368 * by the MAC system, so only things with backing by a
369 * normal object (read: vnodes) are checked.
370 */
371 if (object->type != OBJT_VNODE)
372 continue;
373 vp = (struct vnode *)object->handle;
374 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
375 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
376 result = vme->max_protection;
377 mac_check_vnode_mmap_downgrade(cred, vp, &result);
378 VOP_UNLOCK(vp, 0, td);
379 /*
380 * Find out what maximum protection we may be allowing
381 * now but a policy needs to get removed.
382 */
383 revokeperms = vme->max_protection & ~result;
384 if (!revokeperms) {
385 VFS_UNLOCK_GIANT(vfslocked);
386 continue;
387 }
388 printf("pid %ld: revoking %s perms from %#lx:%ld "
389 "(max %s/cur %s)\n", (long)td->td_proc->p_pid,
390 prot2str(revokeperms), (u_long)vme->start,
391 (long)(vme->end - vme->start),
392 prot2str(vme->max_protection), prot2str(vme->protection));
393 vm_map_lock_upgrade(map);
394 /*
395 * This is the really simple case: if a map has more
396 * max_protection than is allowed, but it's not being
397 * actually used (that is, the current protection is
398 * still allowed), we can just wipe it out and do
399 * nothing more.
400 */
401 if ((vme->protection & revokeperms) == 0) {
402 vme->max_protection -= revokeperms;
403 } else {
404 if (revokeperms & VM_PROT_WRITE) {
405 /*
406 * In the more complicated case, flush out all
407 * pending changes to the object then turn it
408 * copy-on-write.
409 */
410 vm_object_reference(object);
|
| 411 (void) vn_start_write(vp, &mp, V_WAIT); |
412 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
413 VM_OBJECT_LOCK(object);
414 vm_object_page_clean(object,
415 OFF_TO_IDX(offset),
416 OFF_TO_IDX(offset + vme->end - vme->start +
417 PAGE_MASK),
418 OBJPC_SYNC);
419 VM_OBJECT_UNLOCK(object);
420 VOP_UNLOCK(vp, 0, td);
|
| 421 vn_finished_write(mp); |
422 vm_object_deallocate(object);
423 /*
424 * Why bother if there's no read permissions
425 * anymore? For the rest, we need to leave
426 * the write permissions on for COW, or
427 * remove them entirely if configured to.
428 */
429 if (!mac_mmap_revocation_via_cow) {
430 vme->max_protection &= ~VM_PROT_WRITE;
431 vme->protection &= ~VM_PROT_WRITE;
432 } if ((revokeperms & VM_PROT_READ) == 0)
433 vme->eflags |= MAP_ENTRY_COW |
434 MAP_ENTRY_NEEDS_COPY;
435 }
436 if (revokeperms & VM_PROT_EXECUTE) {
437 vme->max_protection &= ~VM_PROT_EXECUTE;
438 vme->protection &= ~VM_PROT_EXECUTE;
439 }
440 if (revokeperms & VM_PROT_READ) {
441 vme->max_protection = 0;
442 vme->protection = 0;
443 }
444 pmap_protect(map->pmap, vme->start, vme->end,
445 vme->protection & ~revokeperms);
446 vm_map_simplify_entry(map, vme);
447 }
448 vm_map_lock_downgrade(map);
449 VFS_UNLOCK_GIANT(vfslocked);
450 }
451 vm_map_unlock_read(map);
452}
453
454/*
455 * When the subject's label changes, it may require revocation of privilege
456 * to mapped objects. This can't be done on-the-fly later with a unified
457 * buffer cache.
458 */
459void
460mac_relabel_cred(struct ucred *cred, struct label *newlabel)
461{
462
463 MAC_PERFORM(relabel_cred, cred, newlabel);
464}
465
466int
467mac_check_cred_relabel(struct ucred *cred, struct label *newlabel)
468{
469 int error;
470
471 MAC_CHECK(check_cred_relabel, cred, newlabel);
472
473 return (error);
474}
475
476int
477mac_check_cred_visible(struct ucred *u1, struct ucred *u2)
478{
479 int error;
480
481 if (!mac_enforce_process)
482 return (0);
483
484 MAC_CHECK(check_cred_visible, u1, u2);
485
486 return (error);
487}
488
489int
490mac_check_proc_debug(struct ucred *cred, struct proc *proc)
491{
492 int error;
493
494 PROC_LOCK_ASSERT(proc, MA_OWNED);
495
496 if (!mac_enforce_process)
497 return (0);
498
499 MAC_CHECK(check_proc_debug, cred, proc);
500
501 return (error);
502}
503
504int
505mac_check_proc_sched(struct ucred *cred, struct proc *proc)
506{
507 int error;
508
509 PROC_LOCK_ASSERT(proc, MA_OWNED);
510
511 if (!mac_enforce_process)
512 return (0);
513
514 MAC_CHECK(check_proc_sched, cred, proc);
515
516 return (error);
517}
518
519int
520mac_check_proc_signal(struct ucred *cred, struct proc *proc, int signum)
521{
522 int error;
523
524 PROC_LOCK_ASSERT(proc, MA_OWNED);
525
526 if (!mac_enforce_process)
527 return (0);
528
529 MAC_CHECK(check_proc_signal, cred, proc, signum);
530
531 return (error);
532}
533
534int
535mac_check_proc_setuid(struct proc *proc, struct ucred *cred, uid_t uid)
536{
537 int error;
538
539 PROC_LOCK_ASSERT(proc, MA_OWNED);
540
541 if (!mac_enforce_suid)
542 return (0);
543
544 MAC_CHECK(check_proc_setuid, cred, uid);
545 return (error);
546}
547
548int
549mac_check_proc_seteuid(struct proc *proc, struct ucred *cred, uid_t euid)
550{
551 int error;
552
553 PROC_LOCK_ASSERT(proc, MA_OWNED);
554
555 if (!mac_enforce_suid)
556 return (0);
557
558 MAC_CHECK(check_proc_seteuid, cred, euid);
559 return (error);
560}
561
562int
563mac_check_proc_setgid(struct proc *proc, struct ucred *cred, gid_t gid)
564{
565 int error;
566
567 PROC_LOCK_ASSERT(proc, MA_OWNED);
568
569 if (!mac_enforce_suid)
570 return (0);
571
572 MAC_CHECK(check_proc_setgid, cred, gid);
573 return (error);
574}
575
576int
577mac_check_proc_setegid(struct proc *proc, struct ucred *cred, gid_t egid)
578{
579 int error;
580
581 PROC_LOCK_ASSERT(proc, MA_OWNED);
582
583 if (!mac_enforce_suid)
584 return (0);
585
586 MAC_CHECK(check_proc_setegid, cred, egid);
587 return (error);
588}
589
590int
591mac_check_proc_setgroups(struct proc *proc, struct ucred *cred,
592 int ngroups, gid_t *gidset)
593{
594 int error;
595
596 PROC_LOCK_ASSERT(proc, MA_OWNED);
597
598 if (!mac_enforce_suid)
599 return (0);
600
601 MAC_CHECK(check_proc_setgroups, cred, ngroups, gidset);
602 return (error);
603}
604
605int
606mac_check_proc_setreuid(struct proc *proc, struct ucred *cred, uid_t ruid,
607 uid_t euid)
608{
609 int error;
610
611 PROC_LOCK_ASSERT(proc, MA_OWNED);
612
613 if (!mac_enforce_suid)
614 return (0);
615
616 MAC_CHECK(check_proc_setreuid, cred, ruid, euid);
617 return (error);
618}
619
620int
621mac_check_proc_setregid(struct proc *proc, struct ucred *cred, gid_t rgid,
622 gid_t egid)
623{
624 int error;
625
626 PROC_LOCK_ASSERT(proc, MA_OWNED);
627
628 if (!mac_enforce_suid)
629 return (0);
630
631 MAC_CHECK(check_proc_setregid, cred, rgid, egid);
632 return (error);
633}
634
635int
636mac_check_proc_setresuid(struct proc *proc, struct ucred *cred, uid_t ruid,
637 uid_t euid, uid_t suid)
638{
639 int error;
640
641 PROC_LOCK_ASSERT(proc, MA_OWNED);
642
643 if (!mac_enforce_suid)
644 return (0);
645
646 MAC_CHECK(check_proc_setresuid, cred, ruid, euid, suid);
647 return (error);
648}
649
650int
651mac_check_proc_setresgid(struct proc *proc, struct ucred *cred, gid_t rgid,
652 gid_t egid, gid_t sgid)
653{
654 int error;
655
656 PROC_LOCK_ASSERT(proc, MA_OWNED);
657
658 if (!mac_enforce_suid)
659 return (0);
660
661 MAC_CHECK(check_proc_setresgid, cred, rgid, egid, sgid);
662 return (error);
663}
664
665int
666mac_check_proc_wait(struct ucred *cred, struct proc *proc)
667{
668 int error;
669
670 PROC_LOCK_ASSERT(proc, MA_OWNED);
671
672 if (!mac_enforce_process)
673 return (0);
674
675 MAC_CHECK(check_proc_wait, cred, proc);
676
677 return (error);
678}
|