44
45#include "opt_mac.h"
46
47#include <sys/param.h>
48#include <sys/condvar.h>
49#include <sys/imgact.h>
50#include <sys/kernel.h>
51#include <sys/lock.h>
52#include <sys/malloc.h>
53#include <sys/mutex.h>
54#include <sys/mac.h>
55#include <sys/proc.h>
56#include <sys/sbuf.h>
57#include <sys/systm.h>
58#include <sys/vnode.h>
59#include <sys/mount.h>
60#include <sys/file.h>
61#include <sys/namei.h>
62#include <sys/sysctl.h>
63
64#include <vm/vm.h>
65#include <vm/pmap.h>
66#include <vm/vm_map.h>
67#include <vm/vm_object.h>
68
69#include <security/mac/mac_framework.h>
70#include <security/mac/mac_internal.h>
71#include <security/mac/mac_policy.h>
72
73static int mac_mmap_revocation = 1;
74SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW,
75 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject "
76 "relabel");
77
78static int mac_mmap_revocation_via_cow = 0;
79SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW,
80 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via "
81 "copy-on-write semantics, or by removing all write access");
82
83static void mac_cred_mmapped_drop_perms_recurse(struct thread *td,
84 struct ucred *cred, struct vm_map *map);
85
86struct label *
87mac_cred_label_alloc(void)
88{
89 struct label *label;
90
91 label = mac_labelzone_alloc(M_WAITOK);
92 MAC_PERFORM(cred_init_label, label);
93 return (label);
94}
95
96void
97mac_cred_init(struct ucred *cred)
98{
99
100 cred->cr_label = mac_cred_label_alloc();
101}
102
103static struct label *
104mac_proc_label_alloc(void)
105{
106 struct label *label;
107
108 label = mac_labelzone_alloc(M_WAITOK);
109 MAC_PERFORM(proc_init_label, label);
110 return (label);
111}
112
113void
114mac_proc_init(struct proc *p)
115{
116
117 p->p_label = mac_proc_label_alloc();
118}
119
120void
121mac_cred_label_free(struct label *label)
122{
123
124 MAC_PERFORM(cred_destroy_label, label);
125 mac_labelzone_free(label);
126}
127
128void
129mac_cred_destroy(struct ucred *cred)
130{
131
132 mac_cred_label_free(cred->cr_label);
133 cred->cr_label = NULL;
134}
135
136static void
137mac_proc_label_free(struct label *label)
138{
139
140 MAC_PERFORM(proc_destroy_label, label);
141 mac_labelzone_free(label);
142}
143
144void
145mac_proc_destroy(struct proc *p)
146{
147
148 mac_proc_label_free(p->p_label);
149 p->p_label = NULL;
150}
151
152int
153mac_cred_externalize_label(struct label *label, char *elements,
154 char *outbuf, size_t outbuflen)
155{
156 int error;
157
158 MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen);
159
160 return (error);
161}
162
163int
164mac_cred_internalize_label(struct label *label, char *string)
165{
166 int error;
167
168 MAC_INTERNALIZE(cred, label, string);
169
170 return (error);
171}
172
173/*
174 * Initialize MAC label for the first kernel process, from which other kernel
175 * processes and threads are spawned.
176 */
177void
178mac_proc_create_swapper(struct ucred *cred)
179{
180
181 MAC_PERFORM(proc_create_swapper, cred);
182}
183
184/*
185 * Initialize MAC label for the first userland process, from which other
186 * userland processes and threads are spawned.
187 */
188void
189mac_proc_create_init(struct ucred *cred)
190{
191
192 MAC_PERFORM(proc_create_init, cred);
193}
194
|
212mac_thread_userret(struct thread *td)
213{
214
215 MAC_PERFORM(thread_userret, td);
216}
217
218/*
219 * When a new process is created, its label must be initialized. Generally,
220 * this involves inheritence from the parent process, modulo possible deltas.
221 * This function allows that processing to take place.
222 */
223void
224mac_cred_copy(struct ucred *src, struct ucred *dest)
225{
226
227 MAC_PERFORM(cred_copy_label, src->cr_label, dest->cr_label);
228}
229
230int
231mac_execve_enter(struct image_params *imgp, struct mac *mac_p)
232{
233 struct label *label;
234 struct mac mac;
235 char *buffer;
236 int error;
237
238 if (mac_p == NULL)
239 return (0);
240
241 error = copyin(mac_p, &mac, sizeof(mac));
242 if (error)
243 return (error);
244
245 error = mac_check_structmac_consistent(&mac);
246 if (error)
247 return (error);
248
249 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK);
250 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL);
251 if (error) {
252 free(buffer, M_MACTEMP);
253 return (error);
254 }
255
256 label = mac_cred_label_alloc();
257 error = mac_cred_internalize_label(label, buffer);
258 free(buffer, M_MACTEMP);
259 if (error) {
260 mac_cred_label_free(label);
261 return (error);
262 }
263 imgp->execlabel = label;
264 return (0);
265}
266
267void
268mac_execve_exit(struct image_params *imgp)
269{
270 if (imgp->execlabel != NULL) {
271 mac_cred_label_free(imgp->execlabel);
272 imgp->execlabel = NULL;
273 }
274}
275
276/*
277 * When relabeling a process, call out to the policies for the maximum
278 * permission allowed for each object type we know about in its memory space,
279 * and revoke access (in the least surprising ways we know) when necessary.
280 * The process lock is not held here.
281 */
282void
283mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred)
284{
285
286 /* XXX freeze all other threads */
287 mac_cred_mmapped_drop_perms_recurse(td, cred,
288 &td->td_proc->p_vmspace->vm_map);
289 /* XXX allow other threads to continue */
290}
291
292static __inline const char *
293prot2str(vm_prot_t prot)
294{
295
296 switch (prot & VM_PROT_ALL) {
297 case VM_PROT_READ:
298 return ("r--");
299 case VM_PROT_READ | VM_PROT_WRITE:
300 return ("rw-");
301 case VM_PROT_READ | VM_PROT_EXECUTE:
302 return ("r-x");
303 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE:
304 return ("rwx");
305 case VM_PROT_WRITE:
306 return ("-w-");
307 case VM_PROT_EXECUTE:
308 return ("--x");
309 case VM_PROT_WRITE | VM_PROT_EXECUTE:
310 return ("-wx");
311 default:
312 return ("---");
313 }
314}
315
316static void
317mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
318 struct vm_map *map)
319{
320 struct vm_map_entry *vme;
321 int vfslocked, result;
322 vm_prot_t revokeperms;
323 vm_object_t backing_object, object;
324 vm_ooffset_t offset;
325 struct vnode *vp;
326 struct mount *mp;
327
328 if (!mac_mmap_revocation)
329 return;
330
331 vm_map_lock_read(map);
332 for (vme = map->header.next; vme != &map->header; vme = vme->next) {
333 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
334 mac_cred_mmapped_drop_perms_recurse(td, cred,
335 vme->object.sub_map);
336 continue;
337 }
338 /*
339 * Skip over entries that obviously are not shared.
340 */
341 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) ||
342 !vme->max_protection)
343 continue;
344 /*
345 * Drill down to the deepest backing object.
346 */
347 offset = vme->offset;
348 object = vme->object.vm_object;
349 if (object == NULL)
350 continue;
351 VM_OBJECT_LOCK(object);
352 while ((backing_object = object->backing_object) != NULL) {
353 VM_OBJECT_LOCK(backing_object);
354 offset += object->backing_object_offset;
355 VM_OBJECT_UNLOCK(object);
356 object = backing_object;
357 }
358 VM_OBJECT_UNLOCK(object);
359 /*
360 * At the moment, vm_maps and objects aren't considered by
361 * the MAC system, so only things with backing by a normal
362 * object (read: vnodes) are checked.
363 */
364 if (object->type != OBJT_VNODE)
365 continue;
366 vp = (struct vnode *)object->handle;
367 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
368 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
369 result = vme->max_protection;
370 mac_vnode_check_mmap_downgrade(cred, vp, &result);
371 VOP_UNLOCK(vp, 0, td);
372 /*
373 * Find out what maximum protection we may be allowing now
374 * but a policy needs to get removed.
375 */
376 revokeperms = vme->max_protection & ~result;
377 if (!revokeperms) {
378 VFS_UNLOCK_GIANT(vfslocked);
379 continue;
380 }
381 printf("pid %ld: revoking %s perms from %#lx:%ld "
382 "(max %s/cur %s)\n", (long)td->td_proc->p_pid,
383 prot2str(revokeperms), (u_long)vme->start,
384 (long)(vme->end - vme->start),
385 prot2str(vme->max_protection), prot2str(vme->protection));
386 vm_map_lock_upgrade(map);
387 /*
388 * This is the really simple case: if a map has more
389 * max_protection than is allowed, but it's not being
390 * actually used (that is, the current protection is still
391 * allowed), we can just wipe it out and do nothing more.
392 */
393 if ((vme->protection & revokeperms) == 0) {
394 vme->max_protection -= revokeperms;
395 } else {
396 if (revokeperms & VM_PROT_WRITE) {
397 /*
398 * In the more complicated case, flush out all
399 * pending changes to the object then turn it
400 * copy-on-write.
401 */
402 vm_object_reference(object);
403 (void) vn_start_write(vp, &mp, V_WAIT);
404 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
405 VM_OBJECT_LOCK(object);
406 vm_object_page_clean(object,
407 OFF_TO_IDX(offset),
408 OFF_TO_IDX(offset + vme->end - vme->start +
409 PAGE_MASK),
410 OBJPC_SYNC);
411 VM_OBJECT_UNLOCK(object);
412 VOP_UNLOCK(vp, 0, td);
413 vn_finished_write(mp);
414 vm_object_deallocate(object);
415 /*
416 * Why bother if there's no read permissions
417 * anymore? For the rest, we need to leave
418 * the write permissions on for COW, or
419 * remove them entirely if configured to.
420 */
421 if (!mac_mmap_revocation_via_cow) {
422 vme->max_protection &= ~VM_PROT_WRITE;
423 vme->protection &= ~VM_PROT_WRITE;
424 } if ((revokeperms & VM_PROT_READ) == 0)
425 vme->eflags |= MAP_ENTRY_COW |
426 MAP_ENTRY_NEEDS_COPY;
427 }
428 if (revokeperms & VM_PROT_EXECUTE) {
429 vme->max_protection &= ~VM_PROT_EXECUTE;
430 vme->protection &= ~VM_PROT_EXECUTE;
431 }
432 if (revokeperms & VM_PROT_READ) {
433 vme->max_protection = 0;
434 vme->protection = 0;
435 }
436 pmap_protect(map->pmap, vme->start, vme->end,
437 vme->protection & ~revokeperms);
438 vm_map_simplify_entry(map, vme);
439 }
440 vm_map_lock_downgrade(map);
441 VFS_UNLOCK_GIANT(vfslocked);
442 }
443 vm_map_unlock_read(map);
444}
445
446/*
447 * When the subject's label changes, it may require revocation of privilege
448 * to mapped objects. This can't be done on-the-fly later with a unified
449 * buffer cache.
450 */
451void
452mac_cred_relabel(struct ucred *cred, struct label *newlabel)
453{
454
455 MAC_PERFORM(cred_relabel, cred, newlabel);
456}
457
458int
459mac_cred_check_relabel(struct ucred *cred, struct label *newlabel)
460{
461 int error;
462
463 MAC_CHECK(cred_check_relabel, cred, newlabel);
464
465 return (error);
466}
467
468int
469mac_cred_check_visible(struct ucred *cr1, struct ucred *cr2)
470{
471 int error;
472
473 MAC_CHECK(cred_check_visible, cr1, cr2);
474
475 return (error);
476}
477
478int
479mac_proc_check_debug(struct ucred *cred, struct proc *p)
480{
481 int error;
482
483 PROC_LOCK_ASSERT(p, MA_OWNED);
484
485 MAC_CHECK(proc_check_debug, cred, p);
486
487 return (error);
488}
489
490int
491mac_proc_check_sched(struct ucred *cred, struct proc *p)
492{
493 int error;
494
495 PROC_LOCK_ASSERT(p, MA_OWNED);
496
497 MAC_CHECK(proc_check_sched, cred, p);
498
499 return (error);
500}
501
502int
503mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum)
504{
505 int error;
506
507 PROC_LOCK_ASSERT(p, MA_OWNED);
508
509 MAC_CHECK(proc_check_signal, cred, p, signum);
510
511 return (error);
512}
513
514int
515mac_proc_check_setuid(struct proc *p, struct ucred *cred, uid_t uid)
516{
517 int error;
518
519 PROC_LOCK_ASSERT(p, MA_OWNED);
520
521 MAC_CHECK(proc_check_setuid, cred, uid);
522 return (error);
523}
524
525int
526mac_proc_check_seteuid(struct proc *p, struct ucred *cred, uid_t euid)
527{
528 int error;
529
530 PROC_LOCK_ASSERT(p, MA_OWNED);
531
532 MAC_CHECK(proc_check_seteuid, cred, euid);
533 return (error);
534}
535
536int
537mac_proc_check_setgid(struct proc *p, struct ucred *cred, gid_t gid)
538{
539 int error;
540
541 PROC_LOCK_ASSERT(p, MA_OWNED);
542
543 MAC_CHECK(proc_check_setgid, cred, gid);
544
545 return (error);
546}
547
548int
549mac_proc_check_setegid(struct proc *p, struct ucred *cred, gid_t egid)
550{
551 int error;
552
553 PROC_LOCK_ASSERT(p, MA_OWNED);
554
555 MAC_CHECK(proc_check_setegid, cred, egid);
556
557 return (error);
558}
559
560int
561mac_proc_check_setgroups(struct proc *p, struct ucred *cred, int ngroups,
562 gid_t *gidset)
563{
564 int error;
565
566 PROC_LOCK_ASSERT(p, MA_OWNED);
567
568 MAC_CHECK(proc_check_setgroups, cred, ngroups, gidset);
569 return (error);
570}
571
572int
573mac_proc_check_setreuid(struct proc *p, struct ucred *cred, uid_t ruid,
574 uid_t euid)
575{
576 int error;
577
578 PROC_LOCK_ASSERT(p, MA_OWNED);
579
580 MAC_CHECK(proc_check_setreuid, cred, ruid, euid);
581
582 return (error);
583}
584
585int
586mac_proc_check_setregid(struct proc *proc, struct ucred *cred, gid_t rgid,
587 gid_t egid)
588{
589 int error;
590
591 PROC_LOCK_ASSERT(proc, MA_OWNED);
592
593 MAC_CHECK(proc_check_setregid, cred, rgid, egid);
594
595 return (error);
596}
597
598int
599mac_proc_check_setresuid(struct proc *p, struct ucred *cred, uid_t ruid,
600 uid_t euid, uid_t suid)
601{
602 int error;
603
604 PROC_LOCK_ASSERT(p, MA_OWNED);
605
606 MAC_CHECK(proc_check_setresuid, cred, ruid, euid, suid);
607 return (error);
608}
609
610int
611mac_proc_check_setresgid(struct proc *p, struct ucred *cred, gid_t rgid,
612 gid_t egid, gid_t sgid)
613{
614 int error;
615
616 PROC_LOCK_ASSERT(p, MA_OWNED);
617
618 MAC_CHECK(proc_check_setresgid, cred, rgid, egid, sgid);
619
620 return (error);
621}
622
623int
624mac_proc_check_wait(struct ucred *cred, struct proc *p)
625{
626 int error;
627
628 PROC_LOCK_ASSERT(p, MA_OWNED);
629
630 MAC_CHECK(proc_check_wait, cred, p);
631
632 return (error);
633}
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