security/apparmor/domain.c

   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;
  65         const struct cred *cred = NULL;
  66         struct aa_profile *tracerp = NULL;
  67         int error = 0;
  68
  69         rcu_read_lock();
  70         tracer = ptrace_parent(task);
  71         if (tracer) {
  72                 /* released below */
  73                 cred = get_task_cred(tracer);
  74                 tracerp = aa_cred_profile(cred);
  75         }
  76
  77         /* not ptraced */
  78         if (!tracer || unconfined(tracerp))
  79                 goto out;
  80
  81         error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH);
  82
  83 out:
  84         rcu_read_unlock();
  85         if (cred)
  86                 put_cred(cred);
  87
  88         return error;
  89 }
  90
  91 /**
  92  * change_profile_perms - find permissions for change_profile
  93  * @profile: the current profile  (NOT NULL)
  94  * @ns: the namespace being switched to  (NOT NULL)
  95  * @name: the name of the profile to change to  (NOT NULL)
  96  * @request: requested perms
  97  * @start: state to start matching in
  98  *
  99  * Returns: permission set
 100  */
 101 static struct file_perms change_profile_perms(struct aa_profile *profile,
 102                                               struct aa_namespace *ns,
 103                                               const char *name, u32 request,
 104                                               unsigned int start)
 105 {
 106         struct file_perms perms;
 107         struct path_cond cond = { };
 108         unsigned int state;
 109
 110         if (unconfined(profile)) {
 111                 perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
 112                 perms.audit = perms.quiet = perms.kill = 0;
 113                 return perms;
 114         } else if (!profile->file.dfa) {
 115                 return nullperms;
 116         } else if ((ns == profile->ns)) {
 117                 /* try matching against rules with out namespace prepended */
 118                 aa_str_perms(profile->file.dfa, start, name, &cond, &perms);
 119                 if (COMBINED_PERM_MASK(perms) & request)
 120                         return perms;
 121         }
 122
 123         /* try matching with namespace name and then profile */
 124         state = aa_dfa_match(profile->file.dfa, start, ns->base.name);
 125         state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 126         aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
 127
 128         return perms;
 129 }
 130
 131 /**
 132  * __attach_match_ - find an attachment match
 133  * @name - to match against  (NOT NULL)
 134  * @head - profile list to walk  (NOT NULL)
 135  *
 136  * Do a linear search on the profiles in the list.  There is a matching
 137  * preference where an exact match is preferred over a name which uses
 138  * expressions to match, and matching expressions with the greatest
 139  * xmatch_len are preferred.
 140  *
 141  * Requires: @head not be shared or have appropriate locks held
 142  *
 143  * Returns: profile or NULL if no match found
 144  */
 145 static struct aa_profile *__attach_match(const char *name,
 146                                          struct list_head *head)
 147 {
 148         int len = 0;
 149         struct aa_profile *profile, *candidate = NULL;
 150
 151         list_for_each_entry(profile, head, base.list) {
 152                 if (profile->flags & PFLAG_NULL)
 153                         continue;
 154                 if (profile->xmatch && profile->xmatch_len > len) {
 155                         unsigned int state = aa_dfa_match(profile->xmatch,
 156                                                           DFA_START, name);
 157                         u32 perm = dfa_user_allow(profile->xmatch, state);
 158                         /* any accepting state means a valid match. */
 159                         if (perm & MAY_EXEC) {
 160                                 candidate = profile;
 161                                 len = profile->xmatch_len;
 162                         }
 163                 } else if (!strcmp(profile->base.name, name))
 164                         /* exact non-re match, no more searching required */
 165                         return profile;
 166         }
 167
 168         return candidate;
 169 }
 170
 171 /**
 172  * find_attach - do attachment search for unconfined processes
 173  * @ns: the current namespace  (NOT NULL)
 174  * @list: list to search  (NOT NULL)
 175  * @name: the executable name to match against  (NOT NULL)
 176  *
 177  * Returns: profile or NULL if no match found
 178  */
 179 static struct aa_profile *find_attach(struct aa_namespace *ns,
 180                                       struct list_head *list, const char *name)
 181 {
 182         struct aa_profile *profile;
 183
 184         read_lock(&ns->lock);
 185         profile = aa_get_profile(__attach_match(name, list));
 186         read_unlock(&ns->lock);
 187
 188         return profile;
 189 }
 190
 191 /**
 192  * separate_fqname - separate the namespace and profile names
 193  * @fqname: the fqname name to split  (NOT NULL)
 194  * @ns_name: the namespace name if it exists  (NOT NULL)
 195  *
 196  * This is the xtable equivalent routine of aa_split_fqname.  It finds the
 197  * split in an xtable fqname which contains an embedded \0 instead of a :
 198  * if a namespace is specified.  This is done so the xtable is constant and
 199  * isn't re-split on every lookup.
 200  *
 201  * Either the profile or namespace name may be optional but if the namespace
 202  * is specified the profile name termination must be present.  This results
 203  * in the following possible encodings:
 204  * profile_name\0
 205  * :ns_name\0profile_name\0
 206  * :ns_name\0\0
 207  *
 208  * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
 209  *
 210  * Returns: profile name if it is specified else NULL
 211  */
 212 static const char *separate_fqname(const char *fqname, const char **ns_name)
 213 {
 214         const char *name;
 215
 216         if (fqname[0] == ':') {
 217                 /* In this case there is guaranteed to be two \0 terminators
 218                  * in the string.  They are verified at load time by
 219                  * by unpack_trans_table
 220                  */
 221                 *ns_name = fqname + 1;          /* skip : */
 222                 name = *ns_name + strlen(*ns_name) + 1;
 223                 if (!*name)
 224                         name = NULL;
 225         } else {
 226                 *ns_name = NULL;
 227                 name = fqname;
 228         }
 229
 230         return name;
 231 }
 232
 233 static const char *next_name(int xtype, const char *name)
 234 {
 235         return NULL;
 236 }
 237
 238 /**
 239  * x_table_lookup - lookup an x transition name via transition table
 240  * @profile: current profile (NOT NULL)
 241  * @xindex: index into x transition table
 242  *
 243  * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
 244  */
 245 static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex)
 246 {
 247         struct aa_profile *new_profile = NULL;
 248         struct aa_namespace *ns = profile->ns;
 249         u32 xtype = xindex & AA_X_TYPE_MASK;
 250         int index = xindex & AA_X_INDEX_MASK;
 251         const char *name;
 252
 253         /* index is guaranteed to be in range, validated at load time */
 254         for (name = profile->file.trans.table[index]; !new_profile && name;
 255              name = next_name(xtype, name)) {
 256                 struct aa_namespace *new_ns;
 257                 const char *xname = NULL;
 258
 259                 new_ns = NULL;
 260                 if (xindex & AA_X_CHILD) {
 261                         /* release by caller */
 262                         new_profile = aa_find_child(profile, name);
 263                         continue;
 264                 } else if (*name == ':') {
 265                         /* switching namespace */
 266                         const char *ns_name;
 267                         xname = name = separate_fqname(name, &ns_name);
 268                         if (!xname)
 269                                 /* no name so use profile name */
 270                                 xname = profile->base.hname;
 271                         if (*ns_name == '@') {
 272                                 /* TODO: variable support */
 273                                 ;
 274                         }
 275                         /* released below */
 276                         new_ns = aa_find_namespace(ns, ns_name);
 277                         if (!new_ns)
 278                                 continue;
 279                 } else if (*name == '@') {
 280                         /* TODO: variable support */
 281                         continue;
 282                 } else {
 283                         /* basic namespace lookup */
 284                         xname = name;
 285                 }
 286
 287                 /* released by caller */
 288                 new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname);
 289                 aa_put_namespace(new_ns);
 290         }
 291
 292         /* released by caller */
 293         return new_profile;
 294 }
 295
 296 /**
 297  * x_to_profile - get target profile for a given xindex
 298  * @profile: current profile  (NOT NULL)
 299  * @name: name to lookup (NOT NULL)
 300  * @xindex: index into x transition table
 301  *
 302  * find profile for a transition index
 303  *
 304  * Returns: refcounted profile or NULL if not found available
 305  */
 306 static struct aa_profile *x_to_profile(struct aa_profile *profile,
 307                                        const char *name, u32 xindex)
 308 {
 309         struct aa_profile *new_profile = NULL;
 310         struct aa_namespace *ns = profile->ns;
 311         u32 xtype = xindex & AA_X_TYPE_MASK;
 312
 313         switch (xtype) {
 314         case AA_X_NONE:
 315                 /* fail exec unless ix || ux fallback - handled by caller */
 316                 return NULL;
 317         case AA_X_NAME:
 318                 if (xindex & AA_X_CHILD)
 319                         /* released by caller */
 320                         new_profile = find_attach(ns, &profile->base.profiles,
 321                                                   name);
 322                 else
 323                         /* released by caller */
 324                         new_profile = find_attach(ns, &ns->base.profiles,
 325                                                   name);
 326                 break;
 327         case AA_X_TABLE:
 328                 /* released by caller */
 329                 new_profile = x_table_lookup(profile, xindex);
 330                 break;
 331         }
 332
 333         /* released by caller */
 334         return new_profile;
 335 }
 336
 337 /**
 338  * apparmor_bprm_set_creds - set the new creds on the bprm struct
 339  * @bprm: binprm for the exec  (NOT NULL)
 340  *
 341  * Returns: %0 or error on failure
 342  */
 343 int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 344 {
 345         struct aa_task_cxt *cxt;
 346         struct aa_profile *profile, *new_profile = NULL;
 347         struct aa_namespace *ns;
 348         char *buffer = NULL;
 349         unsigned int state;
 350         struct file_perms perms = {};
 351         struct path_cond cond = {
 352                 bprm->file->f_path.dentry->d_inode->i_uid,
 353                 bprm->file->f_path.dentry->d_inode->i_mode
 354         };
 355         const char *name = NULL, *target = NULL, *info = NULL;
 356         int error = cap_bprm_set_creds(bprm);
 357         if (error)
 358                 return error;
 359
 360         if (bprm->cred_prepared)
 361                 return 0;
 362
 363         cxt = bprm->cred->security;
 364         BUG_ON(!cxt);
 365
 366         profile = aa_get_profile(aa_newest_version(cxt->profile));
 367         /*
 368          * get the namespace from the replacement profile as replacement
 369          * can change the namespace
 370          */
 371         ns = profile->ns;
 372         state = profile->file.start;
 373
 374         /* buffer freed below, name is pointer into buffer */
 375         error = aa_path_name(&bprm->file->f_path, profile->path_flags, &buffer,
 376                              &name, &info);
 377         if (error) {
 378                 if (profile->flags &
 379                     (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED))
 380                         error = 0;
 381                 name = bprm->filename;
 382                 goto audit;
 383         }
 384
 385         /* Test for onexec first as onexec directives override other
 386          * x transitions.
 387          */
 388         if (unconfined(profile)) {
 389                 /* unconfined task */
 390                 if (cxt->onexec)
 391                         /* change_profile on exec already been granted */
 392                         new_profile = aa_get_profile(cxt->onexec);
 393                 else
 394                         new_profile = find_attach(ns, &ns->base.profiles, name);
 395                 if (!new_profile)
 396                         goto cleanup;
 397                 /*
 398                  * NOTE: Domain transitions from unconfined are allowed
 399                  * even when no_new_privs is set because this aways results
 400                  * in a further reduction of permissions.
 401                  */
 402                 goto apply;
 403         }
 404
 405         /* find exec permissions for name */
 406         state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
 407         if (cxt->onexec) {
 408                 struct file_perms cp;
 409                 info = "change_profile onexec";
 410                 if (!(perms.allow & AA_MAY_ONEXEC))
 411                         goto audit;
 412
 413                 /* test if this exec can be paired with change_profile onexec.
 414                  * onexec permission is linked to exec with a standard pairing
 415                  * exec\0change_profile
 416                  */
 417                 state = aa_dfa_null_transition(profile->file.dfa, state);
 418                 cp = change_profile_perms(profile, cxt->onexec->ns,
 419                                           cxt->onexec->base.name,
 420                                           AA_MAY_ONEXEC, state);
 421
 422                 if (!(cp.allow & AA_MAY_ONEXEC))
 423                         goto audit;
 424                 new_profile = aa_get_profile(aa_newest_version(cxt->onexec));
 425                 goto apply;
 426         }
 427
 428         if (perms.allow & MAY_EXEC) {
 429                 /* exec permission determine how to transition */
 430                 new_profile = x_to_profile(profile, name, perms.xindex);
 431                 if (!new_profile) {
 432                         if (perms.xindex & AA_X_INHERIT) {
 433                                 /* (p|c|n)ix - don't change profile but do
 434                                  * use the newest version, which was picked
 435                                  * up above when getting profile
 436                                  */
 437                                 info = "ix fallback";
 438                                 new_profile = aa_get_profile(profile);
 439                                 goto x_clear;
 440                         } else if (perms.xindex & AA_X_UNCONFINED) {
 441                                 new_profile = aa_get_profile(ns->unconfined);
 442                                 info = "ux fallback";
 443                         } else {
 444                                 error = -ENOENT;
 445                                 info = "profile not found";
 446                         }
 447                 }
 448         } else if (COMPLAIN_MODE(profile)) {
 449                 /* no exec permission - are we in learning mode */
 450                 new_profile = aa_new_null_profile(profile, 0);
 451                 if (!new_profile) {
 452                         error = -ENOMEM;
 453                         info = "could not create null profile";
 454                 } else {
 455                         error = -EACCES;
 456                         target = new_profile->base.hname;
 457                 }
 458                 perms.xindex |= AA_X_UNSAFE;
 459         } else
 460                 /* fail exec */
 461                 error = -EACCES;
 462
 463         /*
 464          * Policy has specified a domain transition, if no_new_privs then
 465          * fail the exec.
 466          */
 467         if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) {
 468                 aa_put_profile(new_profile);
 469                 error = -EPERM;
 470                 goto cleanup;
 471         }
 472
 473         if (!new_profile)
 474                 goto audit;
 475
 476         if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 477                 /* FIXME: currently don't mediate shared state */
 478                 ;
 479         }
 480
 481         if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) {
 482                 error = may_change_ptraced_domain(current, new_profile);
 483                 if (error) {
 484                         aa_put_profile(new_profile);
 485                         goto audit;
 486                 }
 487         }
 488
 489         /* Determine if secure exec is needed.
 490          * Can be at this point for the following reasons:
 491          * 1. unconfined switching to confined
 492          * 2. confined switching to different confinement
 493          * 3. confined switching to unconfined
 494          *
 495          * Cases 2 and 3 are marked as requiring secure exec
 496          * (unless policy specified "unsafe exec")
 497          *
 498          * bprm->unsafe is used to cache the AA_X_UNSAFE permission
 499          * to avoid having to recompute in secureexec
 500          */
 501         if (!(perms.xindex & AA_X_UNSAFE)) {
 502                 AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
 503                          name, new_profile->base.hname);
 504                 bprm->unsafe |= AA_SECURE_X_NEEDED;
 505         }
 506 apply:
 507         target = new_profile->base.hname;
 508         /* when transitioning profiles clear unsafe personality bits */
 509         bprm->per_clear |= PER_CLEAR_ON_SETID;
 510
 511 x_clear:
 512         aa_put_profile(cxt->profile);
 513         /* transfer new profile reference will be released when cxt is freed */
 514         cxt->profile = new_profile;
 515
 516         /* clear out all temporary/transitional state from the context */
 517         aa_put_profile(cxt->previous);
 518         aa_put_profile(cxt->onexec);
 519         cxt->previous = NULL;
 520         cxt->onexec = NULL;
 521         cxt->token = 0;
 522
 523 audit:
 524         error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC,
 525                               name, target, cond.uid, info, error);
 526
 527 cleanup:
 528         aa_put_profile(profile);
 529         kfree(buffer);
 530
 531         return error;
 532 }
 533
 534 /**
 535  * apparmor_bprm_secureexec - determine if secureexec is needed
 536  * @bprm: binprm for exec  (NOT NULL)
 537  *
 538  * Returns: %1 if secureexec is needed else %0
 539  */
 540 int apparmor_bprm_secureexec(struct linux_binprm *bprm)
 541 {
 542         int ret = cap_bprm_secureexec(bprm);
 543
 544         /* the decision to use secure exec is computed in set_creds
 545          * and stored in bprm->unsafe.
 546          */
 547         if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED))
 548                 ret = 1;
 549
 550         return ret;
 551 }
 552
 553 /**
 554  * apparmor_bprm_committing_creds - do task cleanup on committing new creds
 555  * @bprm: binprm for the exec  (NOT NULL)
 556  */
 557 void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
 558 {
 559         struct aa_profile *profile = __aa_current_profile();
 560         struct aa_task_cxt *new_cxt = bprm->cred->security;
 561
 562         /* bail out if unconfined or not changing profile */
 563         if ((new_cxt->profile == profile) ||
 564             (unconfined(new_cxt->profile)))
 565                 return;
 566
 567         current->pdeath_signal = 0;
 568
 569         /* reset soft limits and set hard limits for the new profile */
 570         __aa_transition_rlimits(profile, new_cxt->profile);
 571 }
 572
 573 /**
 574  * apparmor_bprm_commited_cred - do cleanup after new creds committed
 575  * @bprm: binprm for the exec  (NOT NULL)
 576  */
 577 void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
 578 {
 579         /* TODO: cleanup signals - ipc mediation */
 580         return;
 581 }
 582
 583 /*
 584  * Functions for self directed profile change
 585  */
 586
 587 /**
 588  * new_compound_name - create an hname with @n2 appended to @n1
 589  * @n1: base of hname  (NOT NULL)
 590  * @n2: name to append (NOT NULL)
 591  *
 592  * Returns: new name or NULL on error
 593  */
 594 static char *new_compound_name(const char *n1, const char *n2)
 595 {
 596         char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL);
 597         if (name)
 598                 sprintf(name, "%s//%s", n1, n2);
 599         return name;
 600 }
 601
 602 /**
 603  * aa_change_hat - change hat to/from subprofile
 604  * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
 605  * @count: number of hat names in @hats
 606  * @token: magic value to validate the hat change
 607  * @permtest: true if this is just a permission test
 608  *
 609  * Change to the first profile specified in @hats that exists, and store
 610  * the @hat_magic in the current task context.  If the count == 0 and the
 611  * @token matches that stored in the current task context, return to the
 612  * top level profile.
 613  *
 614  * Returns %0 on success, error otherwise.
 615  */
 616 int aa_change_hat(const char *hats[], int count, u64 token, bool permtest)
 617 {
 618         const struct cred *cred;
 619         struct aa_task_cxt *cxt;
 620         struct aa_profile *profile, *previous_profile, *hat = NULL;
 621         char *name = NULL;
 622         int i;
 623         struct file_perms perms = {};
 624         const char *target = NULL, *info = NULL;
 625         int error = 0;
 626
 627         /*
 628          * Fail explicitly requested domain transitions if no_new_privs.
 629          * There is no exception for unconfined as change_hat is not
 630          * available.
 631          */
 632         if (current->no_new_privs)
 633                 return -EPERM;
 634
 635         /* released below */
 636         cred = get_current_cred();
 637         cxt = cred->security;
 638         profile = aa_cred_profile(cred);
 639         previous_profile = cxt->previous;
 640
 641         if (unconfined(profile)) {
 642                 info = "unconfined";
 643                 error = -EPERM;
 644                 goto audit;
 645         }
 646
 647         if (count) {
 648                 /* attempting to change into a new hat or switch to a sibling */
 649                 struct aa_profile *root;
 650                 root = PROFILE_IS_HAT(profile) ? profile->parent : profile;
 651
 652                 /* find first matching hat */
 653                 for (i = 0; i < count && !hat; i++)
 654                         /* released below */
 655                         hat = aa_find_child(root, hats[i]);
 656                 if (!hat) {
 657                         if (!COMPLAIN_MODE(root) || permtest) {
 658                                 if (list_empty(&root->base.profiles))
 659                                         error = -ECHILD;
 660                                 else
 661                                         error = -ENOENT;
 662                                 goto out;
 663                         }
 664
 665                         /*
 666                          * In complain mode and failed to match any hats.
 667                          * Audit the failure is based off of the first hat
 668                          * supplied.  This is done due how userspace
 669                          * interacts with change_hat.
 670                          *
 671                          * TODO: Add logging of all failed hats
 672                          */
 673
 674                         /* freed below */
 675                         name = new_compound_name(root->base.hname, hats[0]);
 676                         target = name;
 677                         /* released below */
 678                         hat = aa_new_null_profile(profile, 1);
 679                         if (!hat) {
 680                                 info = "failed null profile create";
 681                                 error = -ENOMEM;
 682                                 goto audit;
 683                         }
 684                 } else {
 685                         target = hat->base.hname;
 686                         if (!PROFILE_IS_HAT(hat)) {
 687                                 info = "target not hat";
 688                                 error = -EPERM;
 689                                 goto audit;
 690                         }
 691                 }
 692
 693                 error = may_change_ptraced_domain(current, hat);
 694                 if (error) {
 695                         info = "ptraced";
 696                         error = -EPERM;
 697                         goto audit;
 698                 }
 699
 700                 if (!permtest) {
 701                         error = aa_set_current_hat(hat, token);
 702                         if (error == -EACCES)
 703                                 /* kill task in case of brute force attacks */
 704                                 perms.kill = AA_MAY_CHANGEHAT;
 705                         else if (name && !error)
 706                                 /* reset error for learning of new hats */
 707                                 error = -ENOENT;
 708                 }
 709         } else if (previous_profile) {
 710                 /* Return to saved profile.  Kill task if restore fails
 711                  * to avoid brute force attacks
 712                  */
 713                 target = previous_profile->base.hname;
 714                 error = aa_restore_previous_profile(token);
 715                 perms.kill = AA_MAY_CHANGEHAT;
 716         } else
 717                 /* ignore restores when there is no saved profile */
 718                 goto out;
 719
 720 audit:
 721         if (!permtest)
 722                 error = aa_audit_file(profile, &perms, GFP_KERNEL,
 723                                       OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL,
 724                                       target, 0, info, error);
 725
 726 out:
 727         aa_put_profile(hat);
 728         kfree(name);
 729         put_cred(cred);
 730
 731         return error;
 732 }
 733
 734 /**
 735  * aa_change_profile - perform a one-way profile transition
 736  * @ns_name: name of the profile namespace to change to (MAYBE NULL)
 737  * @hname: name of profile to change to (MAYBE NULL)
 738  * @onexec: whether this transition is to take place immediately or at exec
 739  * @permtest: true if this is just a permission test
 740  *
 741  * Change to new profile @name.  Unlike with hats, there is no way
 742  * to change back.  If @name isn't specified the current profile name is
 743  * used.
 744  * If @onexec then the transition is delayed until
 745  * the next exec.
 746  *
 747  * Returns %0 on success, error otherwise.
 748  */
 749 int aa_change_profile(const char *ns_name, const char *hname, bool onexec,
 750                       bool permtest)
 751 {
 752         const struct cred *cred;
 753         struct aa_task_cxt *cxt;
 754         struct aa_profile *profile, *target = NULL;
 755         struct aa_namespace *ns = NULL;
 756         struct file_perms perms = {};
 757         const char *name = NULL, *info = NULL;
 758         int op, error = 0;
 759         u32 request;
 760
 761         if (!hname && !ns_name)
 762                 return -EINVAL;
 763
 764         if (onexec) {
 765                 request = AA_MAY_ONEXEC;
 766                 op = OP_CHANGE_ONEXEC;
 767         } else {
 768                 request = AA_MAY_CHANGE_PROFILE;
 769                 op = OP_CHANGE_PROFILE;
 770         }
 771
 772         cred = get_current_cred();
 773         cxt = cred->security;
 774         profile = aa_cred_profile(cred);
 775
 776         /*
 777          * Fail explicitly requested domain transitions if no_new_privs
 778          * and not unconfined.
 779          * Domain transitions from unconfined are allowed even when
 780          * no_new_privs is set because this aways results in a reduction
 781          * of permissions.
 782          */
 783         if (current->no_new_privs && !unconfined(profile)) {
 784                 put_cred(cred);
 785                 return -EPERM;
 786         }
 787
 788         if (ns_name) {
 789                 /* released below */
 790                 ns = aa_find_namespace(profile->ns, ns_name);
 791                 if (!ns) {
 792                         /* we don't create new namespace in complain mode */
 793                         name = ns_name;
 794                         info = "namespace not found";
 795                         error = -ENOENT;
 796                         goto audit;
 797                 }
 798         } else
 799                 /* released below */
 800                 ns = aa_get_namespace(profile->ns);
 801
 802         /* if the name was not specified, use the name of the current profile */
 803         if (!hname) {
 804                 if (unconfined(profile))
 805                         hname = ns->unconfined->base.hname;
 806                 else
 807                         hname = profile->base.hname;
 808         }
 809
 810         perms = change_profile_perms(profile, ns, hname, request,
 811                                      profile->file.start);
 812         if (!(perms.allow & request)) {
 813                 error = -EACCES;
 814                 goto audit;
 815         }
 816
 817         /* released below */
 818         target = aa_lookup_profile(ns, hname);
 819         if (!target) {
 820                 info = "profile not found";
 821                 error = -ENOENT;
 822                 if (permtest || !COMPLAIN_MODE(profile))
 823                         goto audit;
 824                 /* released below */
 825                 target = aa_new_null_profile(profile, 0);
 826                 if (!target) {
 827                         info = "failed null profile create";
 828                         error = -ENOMEM;
 829                         goto audit;
 830                 }
 831         }
 832
 833         /* check if tracing task is allowed to trace target domain */
 834         error = may_change_ptraced_domain(current, target);
 835         if (error) {
 836                 info = "ptrace prevents transition";
 837                 goto audit;
 838         }
 839
 840         if (permtest)
 841                 goto audit;
 842
 843         if (onexec)
 844                 error = aa_set_current_onexec(target);
 845         else
 846                 error = aa_replace_current_profile(target);
 847
 848 audit:
 849         if (!permtest)
 850                 error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request,
 851                                       name, hname, 0, info, error);
 852
 853         aa_put_namespace(ns);
 854         aa_put_profile(target);
 855         put_cred(cred);
 856
 857         return error;
 858 }