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Linux/security/apparmor/domain.c

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

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