Commit | Line | Data |
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898127c3 JJ |
1 | /* |
2 | * AppArmor security module | |
3 | * | |
4 | * This file contains AppArmor policy attachment and domain transitions | |
5 | * | |
6 | * Copyright (C) 2002-2008 Novell/SUSE | |
7 | * Copyright 2009-2010 Canonical Ltd. | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License as | |
11 | * published by the Free Software Foundation, version 2 of the | |
12 | * License. | |
13 | */ | |
14 | ||
15 | #include <linux/errno.h> | |
16 | #include <linux/fdtable.h> | |
17 | #include <linux/file.h> | |
18 | #include <linux/mount.h> | |
19 | #include <linux/syscalls.h> | |
20 | #include <linux/tracehook.h> | |
21 | #include <linux/personality.h> | |
22 | ||
23 | #include "include/audit.h" | |
24 | #include "include/apparmorfs.h" | |
25 | #include "include/context.h" | |
26 | #include "include/domain.h" | |
27 | #include "include/file.h" | |
28 | #include "include/ipc.h" | |
29 | #include "include/match.h" | |
30 | #include "include/path.h" | |
31 | #include "include/policy.h" | |
32 | ||
33 | /** | |
34 | * aa_free_domain_entries - free entries in a domain table | |
35 | * @domain: the domain table to free (MAYBE NULL) | |
36 | */ | |
37 | void aa_free_domain_entries(struct aa_domain *domain) | |
38 | { | |
39 | int i; | |
40 | if (domain) { | |
41 | if (!domain->table) | |
42 | return; | |
43 | ||
44 | for (i = 0; i < domain->size; i++) | |
45 | kzfree(domain->table[i]); | |
46 | kzfree(domain->table); | |
47 | domain->table = NULL; | |
48 | } | |
49 | } | |
50 | ||
51 | /** | |
52 | * may_change_ptraced_domain - check if can change profile on ptraced task | |
53 | * @task: task we want to change profile of (NOT NULL) | |
54 | * @to_profile: profile to change to (NOT NULL) | |
55 | * | |
56 | * Check if the task is ptraced and if so if the tracing task is allowed | |
57 | * to trace the new domain | |
58 | * | |
59 | * Returns: %0 or error if change not allowed | |
60 | */ | |
61 | static int may_change_ptraced_domain(struct task_struct *task, | |
62 | struct aa_profile *to_profile) | |
63 | { | |
64 | struct task_struct *tracer; | |
898127c3 JJ |
65 | struct aa_profile *tracerp = NULL; |
66 | int error = 0; | |
67 | ||
68 | rcu_read_lock(); | |
06d98473 | 69 | tracer = ptrace_parent(task); |
3cfcc19e | 70 | if (tracer) |
898127c3 | 71 | /* released below */ |
3cfcc19e | 72 | tracerp = aa_get_task_profile(tracer); |
898127c3 JJ |
73 | |
74 | /* not ptraced */ | |
75 | if (!tracer || unconfined(tracerp)) | |
76 | goto out; | |
77 | ||
78 | error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH); | |
79 | ||
80 | out: | |
04fdc099 | 81 | rcu_read_unlock(); |
3cfcc19e | 82 | aa_put_profile(tracerp); |
898127c3 JJ |
83 | |
84 | return error; | |
85 | } | |
86 | ||
87 | /** | |
88 | * change_profile_perms - find permissions for change_profile | |
89 | * @profile: the current profile (NOT NULL) | |
90 | * @ns: the namespace being switched to (NOT NULL) | |
91 | * @name: the name of the profile to change to (NOT NULL) | |
92 | * @request: requested perms | |
93 | * @start: state to start matching in | |
94 | * | |
95 | * Returns: permission set | |
96 | */ | |
97 | static struct file_perms change_profile_perms(struct aa_profile *profile, | |
98 | struct aa_namespace *ns, | |
99 | const char *name, u32 request, | |
100 | unsigned int start) | |
101 | { | |
102 | struct file_perms perms; | |
103 | struct path_cond cond = { }; | |
104 | unsigned int state; | |
105 | ||
106 | if (unconfined(profile)) { | |
107 | perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC; | |
108 | perms.audit = perms.quiet = perms.kill = 0; | |
109 | return perms; | |
110 | } else if (!profile->file.dfa) { | |
111 | return nullperms; | |
112 | } else if ((ns == profile->ns)) { | |
113 | /* try matching against rules with out namespace prepended */ | |
114 | aa_str_perms(profile->file.dfa, start, name, &cond, &perms); | |
115 | if (COMBINED_PERM_MASK(perms) & request) | |
116 | return perms; | |
117 | } | |
118 | ||
119 | /* try matching with namespace name and then profile */ | |
120 | state = aa_dfa_match(profile->file.dfa, start, ns->base.name); | |
121 | state = aa_dfa_match_len(profile->file.dfa, state, ":", 1); | |
122 | aa_str_perms(profile->file.dfa, state, name, &cond, &perms); | |
123 | ||
124 | return perms; | |
125 | } | |
126 | ||
127 | /** | |
128 | * __attach_match_ - find an attachment match | |
129 | * @name - to match against (NOT NULL) | |
130 | * @head - profile list to walk (NOT NULL) | |
131 | * | |
132 | * Do a linear search on the profiles in the list. There is a matching | |
133 | * preference where an exact match is preferred over a name which uses | |
134 | * expressions to match, and matching expressions with the greatest | |
135 | * xmatch_len are preferred. | |
136 | * | |
137 | * Requires: @head not be shared or have appropriate locks held | |
138 | * | |
139 | * Returns: profile or NULL if no match found | |
140 | */ | |
141 | static struct aa_profile *__attach_match(const char *name, | |
142 | struct list_head *head) | |
143 | { | |
144 | int len = 0; | |
145 | struct aa_profile *profile, *candidate = NULL; | |
146 | ||
147 | list_for_each_entry(profile, head, base.list) { | |
148 | if (profile->flags & PFLAG_NULL) | |
149 | continue; | |
150 | if (profile->xmatch && profile->xmatch_len > len) { | |
151 | unsigned int state = aa_dfa_match(profile->xmatch, | |
152 | DFA_START, name); | |
153 | u32 perm = dfa_user_allow(profile->xmatch, state); | |
154 | /* any accepting state means a valid match. */ | |
155 | if (perm & MAY_EXEC) { | |
156 | candidate = profile; | |
157 | len = profile->xmatch_len; | |
158 | } | |
159 | } else if (!strcmp(profile->base.name, name)) | |
160 | /* exact non-re match, no more searching required */ | |
161 | return profile; | |
162 | } | |
163 | ||
164 | return candidate; | |
165 | } | |
166 | ||
167 | /** | |
168 | * find_attach - do attachment search for unconfined processes | |
169 | * @ns: the current namespace (NOT NULL) | |
170 | * @list: list to search (NOT NULL) | |
171 | * @name: the executable name to match against (NOT NULL) | |
172 | * | |
173 | * Returns: profile or NULL if no match found | |
174 | */ | |
175 | static struct aa_profile *find_attach(struct aa_namespace *ns, | |
176 | struct list_head *list, const char *name) | |
177 | { | |
178 | struct aa_profile *profile; | |
179 | ||
180 | read_lock(&ns->lock); | |
181 | profile = aa_get_profile(__attach_match(name, list)); | |
182 | read_unlock(&ns->lock); | |
183 | ||
184 | return profile; | |
185 | } | |
186 | ||
187 | /** | |
188 | * separate_fqname - separate the namespace and profile names | |
189 | * @fqname: the fqname name to split (NOT NULL) | |
190 | * @ns_name: the namespace name if it exists (NOT NULL) | |
191 | * | |
192 | * This is the xtable equivalent routine of aa_split_fqname. It finds the | |
193 | * split in an xtable fqname which contains an embedded \0 instead of a : | |
194 | * if a namespace is specified. This is done so the xtable is constant and | |
195 | * isn't re-split on every lookup. | |
196 | * | |
197 | * Either the profile or namespace name may be optional but if the namespace | |
198 | * is specified the profile name termination must be present. This results | |
199 | * in the following possible encodings: | |
200 | * profile_name\0 | |
201 | * :ns_name\0profile_name\0 | |
202 | * :ns_name\0\0 | |
203 | * | |
204 | * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table | |
205 | * | |
206 | * Returns: profile name if it is specified else NULL | |
207 | */ | |
208 | static const char *separate_fqname(const char *fqname, const char **ns_name) | |
209 | { | |
210 | const char *name; | |
211 | ||
212 | if (fqname[0] == ':') { | |
213 | /* In this case there is guaranteed to be two \0 terminators | |
214 | * in the string. They are verified at load time by | |
215 | * by unpack_trans_table | |
216 | */ | |
217 | *ns_name = fqname + 1; /* skip : */ | |
218 | name = *ns_name + strlen(*ns_name) + 1; | |
219 | if (!*name) | |
220 | name = NULL; | |
221 | } else { | |
222 | *ns_name = NULL; | |
223 | name = fqname; | |
224 | } | |
225 | ||
226 | return name; | |
227 | } | |
228 | ||
229 | static const char *next_name(int xtype, const char *name) | |
230 | { | |
231 | return NULL; | |
232 | } | |
233 | ||
234 | /** | |
235 | * x_table_lookup - lookup an x transition name via transition table | |
236 | * @profile: current profile (NOT NULL) | |
237 | * @xindex: index into x transition table | |
238 | * | |
239 | * Returns: refcounted profile, or NULL on failure (MAYBE NULL) | |
240 | */ | |
241 | static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex) | |
242 | { | |
243 | struct aa_profile *new_profile = NULL; | |
244 | struct aa_namespace *ns = profile->ns; | |
245 | u32 xtype = xindex & AA_X_TYPE_MASK; | |
246 | int index = xindex & AA_X_INDEX_MASK; | |
247 | const char *name; | |
248 | ||
249 | /* index is guaranteed to be in range, validated at load time */ | |
250 | for (name = profile->file.trans.table[index]; !new_profile && name; | |
251 | name = next_name(xtype, name)) { | |
252 | struct aa_namespace *new_ns; | |
253 | const char *xname = NULL; | |
254 | ||
255 | new_ns = NULL; | |
256 | if (xindex & AA_X_CHILD) { | |
257 | /* release by caller */ | |
258 | new_profile = aa_find_child(profile, name); | |
259 | continue; | |
260 | } else if (*name == ':') { | |
261 | /* switching namespace */ | |
262 | const char *ns_name; | |
263 | xname = name = separate_fqname(name, &ns_name); | |
264 | if (!xname) | |
265 | /* no name so use profile name */ | |
266 | xname = profile->base.hname; | |
267 | if (*ns_name == '@') { | |
268 | /* TODO: variable support */ | |
269 | ; | |
270 | } | |
271 | /* released below */ | |
272 | new_ns = aa_find_namespace(ns, ns_name); | |
273 | if (!new_ns) | |
274 | continue; | |
275 | } else if (*name == '@') { | |
276 | /* TODO: variable support */ | |
277 | continue; | |
278 | } else { | |
279 | /* basic namespace lookup */ | |
280 | xname = name; | |
281 | } | |
282 | ||
283 | /* released by caller */ | |
284 | new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname); | |
285 | aa_put_namespace(new_ns); | |
286 | } | |
287 | ||
288 | /* released by caller */ | |
289 | return new_profile; | |
290 | } | |
291 | ||
292 | /** | |
293 | * x_to_profile - get target profile for a given xindex | |
294 | * @profile: current profile (NOT NULL) | |
295 | * @name: name to lookup (NOT NULL) | |
296 | * @xindex: index into x transition table | |
297 | * | |
298 | * find profile for a transition index | |
299 | * | |
300 | * Returns: refcounted profile or NULL if not found available | |
301 | */ | |
302 | static struct aa_profile *x_to_profile(struct aa_profile *profile, | |
303 | const char *name, u32 xindex) | |
304 | { | |
305 | struct aa_profile *new_profile = NULL; | |
306 | struct aa_namespace *ns = profile->ns; | |
307 | u32 xtype = xindex & AA_X_TYPE_MASK; | |
308 | ||
309 | switch (xtype) { | |
310 | case AA_X_NONE: | |
311 | /* fail exec unless ix || ux fallback - handled by caller */ | |
312 | return NULL; | |
313 | case AA_X_NAME: | |
314 | if (xindex & AA_X_CHILD) | |
315 | /* released by caller */ | |
316 | new_profile = find_attach(ns, &profile->base.profiles, | |
317 | name); | |
318 | else | |
319 | /* released by caller */ | |
320 | new_profile = find_attach(ns, &ns->base.profiles, | |
321 | name); | |
322 | break; | |
323 | case AA_X_TABLE: | |
324 | /* released by caller */ | |
325 | new_profile = x_table_lookup(profile, xindex); | |
326 | break; | |
327 | } | |
328 | ||
329 | /* released by caller */ | |
330 | return new_profile; | |
331 | } | |
332 | ||
333 | /** | |
334 | * apparmor_bprm_set_creds - set the new creds on the bprm struct | |
335 | * @bprm: binprm for the exec (NOT NULL) | |
336 | * | |
337 | * Returns: %0 or error on failure | |
338 | */ | |
339 | int apparmor_bprm_set_creds(struct linux_binprm *bprm) | |
340 | { | |
341 | struct aa_task_cxt *cxt; | |
342 | struct aa_profile *profile, *new_profile = NULL; | |
343 | struct aa_namespace *ns; | |
344 | char *buffer = NULL; | |
345 | unsigned int state; | |
346 | struct file_perms perms = {}; | |
347 | struct path_cond cond = { | |
496ad9aa AV |
348 | file_inode(bprm->file)->i_uid, |
349 | file_inode(bprm->file)->i_mode | |
898127c3 JJ |
350 | }; |
351 | const char *name = NULL, *target = NULL, *info = NULL; | |
352 | int error = cap_bprm_set_creds(bprm); | |
353 | if (error) | |
354 | return error; | |
355 | ||
356 | if (bprm->cred_prepared) | |
357 | return 0; | |
358 | ||
359 | cxt = bprm->cred->security; | |
360 | BUG_ON(!cxt); | |
361 | ||
362 | profile = aa_get_profile(aa_newest_version(cxt->profile)); | |
363 | /* | |
364 | * get the namespace from the replacement profile as replacement | |
365 | * can change the namespace | |
366 | */ | |
367 | ns = profile->ns; | |
368 | state = profile->file.start; | |
369 | ||
370 | /* buffer freed below, name is pointer into buffer */ | |
57fa1e18 JJ |
371 | error = aa_path_name(&bprm->file->f_path, profile->path_flags, &buffer, |
372 | &name, &info); | |
898127c3 JJ |
373 | if (error) { |
374 | if (profile->flags & | |
375 | (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED)) | |
376 | error = 0; | |
898127c3 JJ |
377 | name = bprm->filename; |
378 | goto audit; | |
379 | } | |
380 | ||
381 | /* Test for onexec first as onexec directives override other | |
382 | * x transitions. | |
383 | */ | |
384 | if (unconfined(profile)) { | |
385 | /* unconfined task */ | |
386 | if (cxt->onexec) | |
387 | /* change_profile on exec already been granted */ | |
388 | new_profile = aa_get_profile(cxt->onexec); | |
389 | else | |
390 | new_profile = find_attach(ns, &ns->base.profiles, name); | |
391 | if (!new_profile) | |
392 | goto cleanup; | |
c29bceb3 JJ |
393 | /* |
394 | * NOTE: Domain transitions from unconfined are allowed | |
395 | * even when no_new_privs is set because this aways results | |
396 | * in a further reduction of permissions. | |
397 | */ | |
898127c3 JJ |
398 | goto apply; |
399 | } | |
400 | ||
401 | /* find exec permissions for name */ | |
402 | state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms); | |
403 | if (cxt->onexec) { | |
404 | struct file_perms cp; | |
405 | info = "change_profile onexec"; | |
406 | if (!(perms.allow & AA_MAY_ONEXEC)) | |
407 | goto audit; | |
408 | ||
409 | /* test if this exec can be paired with change_profile onexec. | |
410 | * onexec permission is linked to exec with a standard pairing | |
411 | * exec\0change_profile | |
412 | */ | |
413 | state = aa_dfa_null_transition(profile->file.dfa, state); | |
0421ea91 JJ |
414 | cp = change_profile_perms(profile, cxt->onexec->ns, |
415 | cxt->onexec->base.name, | |
898127c3 JJ |
416 | AA_MAY_ONEXEC, state); |
417 | ||
418 | if (!(cp.allow & AA_MAY_ONEXEC)) | |
419 | goto audit; | |
420 | new_profile = aa_get_profile(aa_newest_version(cxt->onexec)); | |
421 | goto apply; | |
422 | } | |
423 | ||
424 | if (perms.allow & MAY_EXEC) { | |
425 | /* exec permission determine how to transition */ | |
426 | new_profile = x_to_profile(profile, name, perms.xindex); | |
427 | if (!new_profile) { | |
428 | if (perms.xindex & AA_X_INHERIT) { | |
429 | /* (p|c|n)ix - don't change profile but do | |
430 | * use the newest version, which was picked | |
431 | * up above when getting profile | |
432 | */ | |
433 | info = "ix fallback"; | |
434 | new_profile = aa_get_profile(profile); | |
435 | goto x_clear; | |
436 | } else if (perms.xindex & AA_X_UNCONFINED) { | |
437 | new_profile = aa_get_profile(ns->unconfined); | |
438 | info = "ux fallback"; | |
439 | } else { | |
440 | error = -ENOENT; | |
441 | info = "profile not found"; | |
17322cc3 JJ |
442 | /* remove MAY_EXEC to audit as failure */ |
443 | perms.allow &= ~MAY_EXEC; | |
898127c3 JJ |
444 | } |
445 | } | |
446 | } else if (COMPLAIN_MODE(profile)) { | |
447 | /* no exec permission - are we in learning mode */ | |
448 | new_profile = aa_new_null_profile(profile, 0); | |
449 | if (!new_profile) { | |
450 | error = -ENOMEM; | |
451 | info = "could not create null profile"; | |
452 | } else { | |
453 | error = -EACCES; | |
454 | target = new_profile->base.hname; | |
455 | } | |
456 | perms.xindex |= AA_X_UNSAFE; | |
457 | } else | |
458 | /* fail exec */ | |
459 | error = -EACCES; | |
460 | ||
c29bceb3 JJ |
461 | /* |
462 | * Policy has specified a domain transition, if no_new_privs then | |
463 | * fail the exec. | |
464 | */ | |
465 | if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) { | |
466 | aa_put_profile(new_profile); | |
467 | error = -EPERM; | |
468 | goto cleanup; | |
469 | } | |
470 | ||
898127c3 JJ |
471 | if (!new_profile) |
472 | goto audit; | |
473 | ||
474 | if (bprm->unsafe & LSM_UNSAFE_SHARE) { | |
475 | /* FIXME: currently don't mediate shared state */ | |
476 | ; | |
477 | } | |
478 | ||
479 | if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) { | |
480 | error = may_change_ptraced_domain(current, new_profile); | |
481 | if (error) { | |
482 | aa_put_profile(new_profile); | |
483 | goto audit; | |
484 | } | |
485 | } | |
486 | ||
487 | /* Determine if secure exec is needed. | |
488 | * Can be at this point for the following reasons: | |
489 | * 1. unconfined switching to confined | |
490 | * 2. confined switching to different confinement | |
491 | * 3. confined switching to unconfined | |
492 | * | |
493 | * Cases 2 and 3 are marked as requiring secure exec | |
494 | * (unless policy specified "unsafe exec") | |
495 | * | |
496 | * bprm->unsafe is used to cache the AA_X_UNSAFE permission | |
497 | * to avoid having to recompute in secureexec | |
498 | */ | |
499 | if (!(perms.xindex & AA_X_UNSAFE)) { | |
500 | AA_DEBUG("scrubbing environment variables for %s profile=%s\n", | |
501 | name, new_profile->base.hname); | |
502 | bprm->unsafe |= AA_SECURE_X_NEEDED; | |
503 | } | |
504 | apply: | |
505 | target = new_profile->base.hname; | |
506 | /* when transitioning profiles clear unsafe personality bits */ | |
507 | bprm->per_clear |= PER_CLEAR_ON_SETID; | |
508 | ||
509 | x_clear: | |
510 | aa_put_profile(cxt->profile); | |
511 | /* transfer new profile reference will be released when cxt is freed */ | |
512 | cxt->profile = new_profile; | |
513 | ||
514 | /* clear out all temporary/transitional state from the context */ | |
515 | aa_put_profile(cxt->previous); | |
516 | aa_put_profile(cxt->onexec); | |
517 | cxt->previous = NULL; | |
518 | cxt->onexec = NULL; | |
519 | cxt->token = 0; | |
520 | ||
521 | audit: | |
522 | error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC, | |
523 | name, target, cond.uid, info, error); | |
524 | ||
525 | cleanup: | |
526 | aa_put_profile(profile); | |
527 | kfree(buffer); | |
528 | ||
529 | return error; | |
530 | } | |
531 | ||
532 | /** | |
533 | * apparmor_bprm_secureexec - determine if secureexec is needed | |
534 | * @bprm: binprm for exec (NOT NULL) | |
535 | * | |
536 | * Returns: %1 if secureexec is needed else %0 | |
537 | */ | |
538 | int apparmor_bprm_secureexec(struct linux_binprm *bprm) | |
539 | { | |
540 | int ret = cap_bprm_secureexec(bprm); | |
541 | ||
542 | /* the decision to use secure exec is computed in set_creds | |
543 | * and stored in bprm->unsafe. | |
544 | */ | |
545 | if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED)) | |
546 | ret = 1; | |
547 | ||
548 | return ret; | |
549 | } | |
550 | ||
551 | /** | |
552 | * apparmor_bprm_committing_creds - do task cleanup on committing new creds | |
553 | * @bprm: binprm for the exec (NOT NULL) | |
554 | */ | |
555 | void apparmor_bprm_committing_creds(struct linux_binprm *bprm) | |
556 | { | |
557 | struct aa_profile *profile = __aa_current_profile(); | |
558 | struct aa_task_cxt *new_cxt = bprm->cred->security; | |
559 | ||
560 | /* bail out if unconfined or not changing profile */ | |
561 | if ((new_cxt->profile == profile) || | |
562 | (unconfined(new_cxt->profile))) | |
563 | return; | |
564 | ||
565 | current->pdeath_signal = 0; | |
566 | ||
567 | /* reset soft limits and set hard limits for the new profile */ | |
568 | __aa_transition_rlimits(profile, new_cxt->profile); | |
569 | } | |
570 | ||
571 | /** | |
572 | * apparmor_bprm_commited_cred - do cleanup after new creds committed | |
573 | * @bprm: binprm for the exec (NOT NULL) | |
574 | */ | |
575 | void apparmor_bprm_committed_creds(struct linux_binprm *bprm) | |
576 | { | |
577 | /* TODO: cleanup signals - ipc mediation */ | |
578 | return; | |
579 | } | |
580 | ||
581 | /* | |
582 | * Functions for self directed profile change | |
583 | */ | |
584 | ||
585 | /** | |
586 | * new_compound_name - create an hname with @n2 appended to @n1 | |
587 | * @n1: base of hname (NOT NULL) | |
588 | * @n2: name to append (NOT NULL) | |
589 | * | |
590 | * Returns: new name or NULL on error | |
591 | */ | |
592 | static char *new_compound_name(const char *n1, const char *n2) | |
593 | { | |
594 | char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL); | |
595 | if (name) | |
596 | sprintf(name, "%s//%s", n1, n2); | |
597 | return name; | |
598 | } | |
599 | ||
600 | /** | |
601 | * aa_change_hat - change hat to/from subprofile | |
602 | * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0) | |
603 | * @count: number of hat names in @hats | |
604 | * @token: magic value to validate the hat change | |
605 | * @permtest: true if this is just a permission test | |
606 | * | |
607 | * Change to the first profile specified in @hats that exists, and store | |
608 | * the @hat_magic in the current task context. If the count == 0 and the | |
609 | * @token matches that stored in the current task context, return to the | |
610 | * top level profile. | |
611 | * | |
612 | * Returns %0 on success, error otherwise. | |
613 | */ | |
614 | int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) | |
615 | { | |
616 | const struct cred *cred; | |
617 | struct aa_task_cxt *cxt; | |
618 | struct aa_profile *profile, *previous_profile, *hat = NULL; | |
619 | char *name = NULL; | |
620 | int i; | |
621 | struct file_perms perms = {}; | |
622 | const char *target = NULL, *info = NULL; | |
623 | int error = 0; | |
624 | ||
c29bceb3 JJ |
625 | /* |
626 | * Fail explicitly requested domain transitions if no_new_privs. | |
627 | * There is no exception for unconfined as change_hat is not | |
628 | * available. | |
629 | */ | |
630 | if (current->no_new_privs) | |
631 | return -EPERM; | |
632 | ||
898127c3 JJ |
633 | /* released below */ |
634 | cred = get_current_cred(); | |
635 | cxt = cred->security; | |
636 | profile = aa_cred_profile(cred); | |
637 | previous_profile = cxt->previous; | |
638 | ||
639 | if (unconfined(profile)) { | |
640 | info = "unconfined"; | |
641 | error = -EPERM; | |
642 | goto audit; | |
643 | } | |
644 | ||
645 | if (count) { | |
646 | /* attempting to change into a new hat or switch to a sibling */ | |
647 | struct aa_profile *root; | |
648 | root = PROFILE_IS_HAT(profile) ? profile->parent : profile; | |
649 | ||
650 | /* find first matching hat */ | |
651 | for (i = 0; i < count && !hat; i++) | |
652 | /* released below */ | |
653 | hat = aa_find_child(root, hats[i]); | |
654 | if (!hat) { | |
655 | if (!COMPLAIN_MODE(root) || permtest) { | |
656 | if (list_empty(&root->base.profiles)) | |
657 | error = -ECHILD; | |
658 | else | |
659 | error = -ENOENT; | |
660 | goto out; | |
661 | } | |
662 | ||
663 | /* | |
664 | * In complain mode and failed to match any hats. | |
665 | * Audit the failure is based off of the first hat | |
666 | * supplied. This is done due how userspace | |
667 | * interacts with change_hat. | |
668 | * | |
669 | * TODO: Add logging of all failed hats | |
670 | */ | |
671 | ||
672 | /* freed below */ | |
673 | name = new_compound_name(root->base.hname, hats[0]); | |
674 | target = name; | |
675 | /* released below */ | |
676 | hat = aa_new_null_profile(profile, 1); | |
677 | if (!hat) { | |
678 | info = "failed null profile create"; | |
679 | error = -ENOMEM; | |
680 | goto audit; | |
681 | } | |
682 | } else { | |
683 | target = hat->base.hname; | |
684 | if (!PROFILE_IS_HAT(hat)) { | |
685 | info = "target not hat"; | |
686 | error = -EPERM; | |
687 | goto audit; | |
688 | } | |
689 | } | |
690 | ||
691 | error = may_change_ptraced_domain(current, hat); | |
692 | if (error) { | |
693 | info = "ptraced"; | |
694 | error = -EPERM; | |
695 | goto audit; | |
696 | } | |
697 | ||
698 | if (!permtest) { | |
699 | error = aa_set_current_hat(hat, token); | |
700 | if (error == -EACCES) | |
701 | /* kill task in case of brute force attacks */ | |
702 | perms.kill = AA_MAY_CHANGEHAT; | |
703 | else if (name && !error) | |
704 | /* reset error for learning of new hats */ | |
705 | error = -ENOENT; | |
706 | } | |
707 | } else if (previous_profile) { | |
708 | /* Return to saved profile. Kill task if restore fails | |
709 | * to avoid brute force attacks | |
710 | */ | |
711 | target = previous_profile->base.hname; | |
712 | error = aa_restore_previous_profile(token); | |
713 | perms.kill = AA_MAY_CHANGEHAT; | |
714 | } else | |
715 | /* ignore restores when there is no saved profile */ | |
716 | goto out; | |
717 | ||
718 | audit: | |
719 | if (!permtest) | |
720 | error = aa_audit_file(profile, &perms, GFP_KERNEL, | |
721 | OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL, | |
2db81452 | 722 | target, GLOBAL_ROOT_UID, info, error); |
898127c3 JJ |
723 | |
724 | out: | |
725 | aa_put_profile(hat); | |
726 | kfree(name); | |
727 | put_cred(cred); | |
728 | ||
729 | return error; | |
730 | } | |
731 | ||
732 | /** | |
733 | * aa_change_profile - perform a one-way profile transition | |
734 | * @ns_name: name of the profile namespace to change to (MAYBE NULL) | |
735 | * @hname: name of profile to change to (MAYBE NULL) | |
736 | * @onexec: whether this transition is to take place immediately or at exec | |
737 | * @permtest: true if this is just a permission test | |
738 | * | |
739 | * Change to new profile @name. Unlike with hats, there is no way | |
740 | * to change back. If @name isn't specified the current profile name is | |
741 | * used. | |
742 | * If @onexec then the transition is delayed until | |
743 | * the next exec. | |
744 | * | |
745 | * Returns %0 on success, error otherwise. | |
746 | */ | |
747 | int aa_change_profile(const char *ns_name, const char *hname, bool onexec, | |
748 | bool permtest) | |
749 | { | |
750 | const struct cred *cred; | |
898127c3 JJ |
751 | struct aa_profile *profile, *target = NULL; |
752 | struct aa_namespace *ns = NULL; | |
753 | struct file_perms perms = {}; | |
754 | const char *name = NULL, *info = NULL; | |
755 | int op, error = 0; | |
756 | u32 request; | |
757 | ||
758 | if (!hname && !ns_name) | |
759 | return -EINVAL; | |
760 | ||
761 | if (onexec) { | |
762 | request = AA_MAY_ONEXEC; | |
763 | op = OP_CHANGE_ONEXEC; | |
764 | } else { | |
765 | request = AA_MAY_CHANGE_PROFILE; | |
766 | op = OP_CHANGE_PROFILE; | |
767 | } | |
768 | ||
769 | cred = get_current_cred(); | |
898127c3 JJ |
770 | profile = aa_cred_profile(cred); |
771 | ||
c29bceb3 JJ |
772 | /* |
773 | * Fail explicitly requested domain transitions if no_new_privs | |
774 | * and not unconfined. | |
775 | * Domain transitions from unconfined are allowed even when | |
776 | * no_new_privs is set because this aways results in a reduction | |
777 | * of permissions. | |
778 | */ | |
779 | if (current->no_new_privs && !unconfined(profile)) { | |
780 | put_cred(cred); | |
781 | return -EPERM; | |
782 | } | |
783 | ||
898127c3 JJ |
784 | if (ns_name) { |
785 | /* released below */ | |
786 | ns = aa_find_namespace(profile->ns, ns_name); | |
787 | if (!ns) { | |
788 | /* we don't create new namespace in complain mode */ | |
789 | name = ns_name; | |
790 | info = "namespace not found"; | |
791 | error = -ENOENT; | |
792 | goto audit; | |
793 | } | |
794 | } else | |
795 | /* released below */ | |
796 | ns = aa_get_namespace(profile->ns); | |
797 | ||
798 | /* if the name was not specified, use the name of the current profile */ | |
799 | if (!hname) { | |
800 | if (unconfined(profile)) | |
801 | hname = ns->unconfined->base.hname; | |
802 | else | |
803 | hname = profile->base.hname; | |
804 | } | |
805 | ||
806 | perms = change_profile_perms(profile, ns, hname, request, | |
807 | profile->file.start); | |
808 | if (!(perms.allow & request)) { | |
809 | error = -EACCES; | |
810 | goto audit; | |
811 | } | |
812 | ||
813 | /* released below */ | |
814 | target = aa_lookup_profile(ns, hname); | |
815 | if (!target) { | |
816 | info = "profile not found"; | |
817 | error = -ENOENT; | |
818 | if (permtest || !COMPLAIN_MODE(profile)) | |
819 | goto audit; | |
820 | /* released below */ | |
821 | target = aa_new_null_profile(profile, 0); | |
822 | if (!target) { | |
823 | info = "failed null profile create"; | |
824 | error = -ENOMEM; | |
825 | goto audit; | |
826 | } | |
827 | } | |
828 | ||
829 | /* check if tracing task is allowed to trace target domain */ | |
830 | error = may_change_ptraced_domain(current, target); | |
831 | if (error) { | |
832 | info = "ptrace prevents transition"; | |
833 | goto audit; | |
834 | } | |
835 | ||
836 | if (permtest) | |
837 | goto audit; | |
838 | ||
839 | if (onexec) | |
840 | error = aa_set_current_onexec(target); | |
841 | else | |
842 | error = aa_replace_current_profile(target); | |
843 | ||
844 | audit: | |
845 | if (!permtest) | |
846 | error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, | |
2db81452 | 847 | name, hname, GLOBAL_ROOT_UID, info, error); |
898127c3 JJ |
848 | |
849 | aa_put_namespace(ns); | |
850 | aa_put_profile(target); | |
851 | put_cred(cred); | |
852 | ||
853 | return error; | |
854 | } |