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 150913 2005-10-04 14:32:15Z csjp $");
|
| 39__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 150923 2005-10-04 14:47:47Z csjp $"); |
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 object;
331 vm_ooffset_t offset;
332 struct vnode *vp;
333
334 if (!mac_mmap_revocation)
335 return;
336
337 vm_map_lock_read(map);
338 for (vme = map->header.next; vme != &map->header; vme = vme->next) {
339 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
340 mac_cred_mmapped_drop_perms_recurse(td, cred,
341 vme->object.sub_map);
342 continue;
343 }
344 /*
345 * Skip over entries that obviously are not shared.
346 */
347 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) ||
348 !vme->max_protection)
349 continue;
350 /*
351 * Drill down to the deepest backing object.
352 */
353 offset = vme->offset;
354 object = vme->object.vm_object;
355 if (object == NULL)
356 continue;
|
357 /* XXXCSJP We need to lock the object before walking
358 * the backing object list.
359 */ |
360 while (object->backing_object != NULL) {
|
358 object = object->backing_object;
|
361 offset += object->backing_object_offset;
|
| 362 object = object->backing_object; |
363 }
364 /*
365 * At the moment, vm_maps and objects aren't considered
366 * by the MAC system, so only things with backing by a
367 * normal object (read: vnodes) are checked.
368 */
369 if (object->type != OBJT_VNODE)
370 continue;
371 vp = (struct vnode *)object->handle;
372 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
373 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
374 result = vme->max_protection;
375 mac_check_vnode_mmap_downgrade(cred, vp, &result);
376 VOP_UNLOCK(vp, 0, td);
377 /*
378 * Find out what maximum protection we may be allowing
379 * now but a policy needs to get removed.
380 */
381 revokeperms = vme->max_protection & ~result;
382 if (!revokeperms) {
383 VFS_UNLOCK_GIANT(vfslocked);
384 continue;
385 }
386 printf("pid %ld: revoking %s perms from %#lx:%ld "
387 "(max %s/cur %s)\n", (long)td->td_proc->p_pid,
388 prot2str(revokeperms), (u_long)vme->start,
389 (long)(vme->end - vme->start),
390 prot2str(vme->max_protection), prot2str(vme->protection));
391 vm_map_lock_upgrade(map);
392 /*
393 * This is the really simple case: if a map has more
394 * max_protection than is allowed, but it's not being
395 * actually used (that is, the current protection is
396 * still allowed), we can just wipe it out and do
397 * nothing more.
398 */
399 if ((vme->protection & revokeperms) == 0) {
400 vme->max_protection -= revokeperms;
401 } else {
402 if (revokeperms & VM_PROT_WRITE) {
403 /*
404 * In the more complicated case, flush out all
405 * pending changes to the object then turn it
406 * copy-on-write.
407 */
408 vm_object_reference(object);
409 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
410 VM_OBJECT_LOCK(object);
411 vm_object_page_clean(object,
412 OFF_TO_IDX(offset),
413 OFF_TO_IDX(offset + vme->end - vme->start +
414 PAGE_MASK),
415 OBJPC_SYNC);
416 VM_OBJECT_UNLOCK(object);
417 VOP_UNLOCK(vp, 0, td);
418 vm_object_deallocate(object);
419 /*
420 * Why bother if there's no read permissions
421 * anymore? For the rest, we need to leave
422 * the write permissions on for COW, or
423 * remove them entirely if configured to.
424 */
425 if (!mac_mmap_revocation_via_cow) {
426 vme->max_protection &= ~VM_PROT_WRITE;
427 vme->protection &= ~VM_PROT_WRITE;
428 } if ((revokeperms & VM_PROT_READ) == 0)
429 vme->eflags |= MAP_ENTRY_COW |
430 MAP_ENTRY_NEEDS_COPY;
431 }
432 if (revokeperms & VM_PROT_EXECUTE) {
433 vme->max_protection &= ~VM_PROT_EXECUTE;
434 vme->protection &= ~VM_PROT_EXECUTE;
435 }
436 if (revokeperms & VM_PROT_READ) {
437 vme->max_protection = 0;
438 vme->protection = 0;
439 }
440 pmap_protect(map->pmap, vme->start, vme->end,
441 vme->protection & ~revokeperms);
442 vm_map_simplify_entry(map, vme);
443 }
444 vm_map_lock_downgrade(map);
445 VFS_UNLOCK_GIANT(vfslocked);
446 }
447 vm_map_unlock_read(map);
448}
449
450/*
451 * When the subject's label changes, it may require revocation of privilege
452 * to mapped objects. This can't be done on-the-fly later with a unified
453 * buffer cache.
454 */
455void
456mac_relabel_cred(struct ucred *cred, struct label *newlabel)
457{
458
459 MAC_PERFORM(relabel_cred, cred, newlabel);
460}
461
462int
463mac_check_cred_relabel(struct ucred *cred, struct label *newlabel)
464{
465 int error;
466
467 MAC_CHECK(check_cred_relabel, cred, newlabel);
468
469 return (error);
470}
471
472int
473mac_check_cred_visible(struct ucred *u1, struct ucred *u2)
474{
475 int error;
476
477 if (!mac_enforce_process)
478 return (0);
479
480 MAC_CHECK(check_cred_visible, u1, u2);
481
482 return (error);
483}
484
485int
486mac_check_proc_debug(struct ucred *cred, struct proc *proc)
487{
488 int error;
489
490 PROC_LOCK_ASSERT(proc, MA_OWNED);
491
492 if (!mac_enforce_process)
493 return (0);
494
495 MAC_CHECK(check_proc_debug, cred, proc);
496
497 return (error);
498}
499
500int
501mac_check_proc_sched(struct ucred *cred, struct proc *proc)
502{
503 int error;
504
505 PROC_LOCK_ASSERT(proc, MA_OWNED);
506
507 if (!mac_enforce_process)
508 return (0);
509
510 MAC_CHECK(check_proc_sched, cred, proc);
511
512 return (error);
513}
514
515int
516mac_check_proc_signal(struct ucred *cred, struct proc *proc, int signum)
517{
518 int error;
519
520 PROC_LOCK_ASSERT(proc, MA_OWNED);
521
522 if (!mac_enforce_process)
523 return (0);
524
525 MAC_CHECK(check_proc_signal, cred, proc, signum);
526
527 return (error);
528}
529
530int
531mac_check_proc_setuid(struct proc *proc, struct ucred *cred, uid_t uid)
532{
533 int error;
534
535 PROC_LOCK_ASSERT(proc, MA_OWNED);
536
537 if (!mac_enforce_suid)
538 return (0);
539
540 MAC_CHECK(check_proc_setuid, cred, uid);
541 return (error);
542}
543
544int
545mac_check_proc_seteuid(struct proc *proc, struct ucred *cred, uid_t euid)
546{
547 int error;
548
549 PROC_LOCK_ASSERT(proc, MA_OWNED);
550
551 if (!mac_enforce_suid)
552 return (0);
553
554 MAC_CHECK(check_proc_seteuid, cred, euid);
555 return (error);
556}
557
558int
559mac_check_proc_setgid(struct proc *proc, struct ucred *cred, gid_t gid)
560{
561 int error;
562
563 PROC_LOCK_ASSERT(proc, MA_OWNED);
564
565 if (!mac_enforce_suid)
566 return (0);
567
568 MAC_CHECK(check_proc_setgid, cred, gid);
569 return (error);
570}
571
572int
573mac_check_proc_setegid(struct proc *proc, struct ucred *cred, gid_t egid)
574{
575 int error;
576
577 PROC_LOCK_ASSERT(proc, MA_OWNED);
578
579 if (!mac_enforce_suid)
580 return (0);
581
582 MAC_CHECK(check_proc_setegid, cred, egid);
583 return (error);
584}
585
586int
587mac_check_proc_setgroups(struct proc *proc, struct ucred *cred,
588 int ngroups, gid_t *gidset)
589{
590 int error;
591
592 PROC_LOCK_ASSERT(proc, MA_OWNED);
593
594 if (!mac_enforce_suid)
595 return (0);
596
597 MAC_CHECK(check_proc_setgroups, cred, ngroups, gidset);
598 return (error);
599}
600
601int
602mac_check_proc_setreuid(struct proc *proc, struct ucred *cred, uid_t ruid,
603 uid_t euid)
604{
605 int error;
606
607 PROC_LOCK_ASSERT(proc, MA_OWNED);
608
609 if (!mac_enforce_suid)
610 return (0);
611
612 MAC_CHECK(check_proc_setreuid, cred, ruid, euid);
613 return (error);
614}
615
616int
617mac_check_proc_setregid(struct proc *proc, struct ucred *cred, gid_t rgid,
618 gid_t egid)
619{
620 int error;
621
622 PROC_LOCK_ASSERT(proc, MA_OWNED);
623
624 if (!mac_enforce_suid)
625 return (0);
626
627 MAC_CHECK(check_proc_setregid, cred, rgid, egid);
628 return (error);
629}
630
631int
632mac_check_proc_setresuid(struct proc *proc, struct ucred *cred, uid_t ruid,
633 uid_t euid, uid_t suid)
634{
635 int error;
636
637 PROC_LOCK_ASSERT(proc, MA_OWNED);
638
639 if (!mac_enforce_suid)
640 return (0);
641
642 MAC_CHECK(check_proc_setresuid, cred, ruid, euid, suid);
643 return (error);
644}
645
646int
647mac_check_proc_setresgid(struct proc *proc, struct ucred *cred, gid_t rgid,
648 gid_t egid, gid_t sgid)
649{
650 int error;
651
652 PROC_LOCK_ASSERT(proc, MA_OWNED);
653
654 if (!mac_enforce_suid)
655 return (0);
656
657 MAC_CHECK(check_proc_setresgid, cred, rgid, egid, sgid);
658 return (error);
659}
660
661int
662mac_check_proc_wait(struct ucred *cred, struct proc *proc)
663{
664 int error;
665
666 PROC_LOCK_ASSERT(proc, MA_OWNED);
667
668 if (!mac_enforce_process)
669 return (0);
670
671 MAC_CHECK(check_proc_wait, cred, proc);
672
673 return (error);
674}
|