security/apparmor/domain.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor policy attachment and domain transitions
   6  *
   7  * Copyright (C) 2002-2008 Novell/SUSE
   8  * Copyright 2009-2010 Canonical Ltd.
   9  */
  10
  11 #include <linux/errno.h>
  12 #include <linux/fdtable.h>
  13 #include <linux/file.h>
  14 #include <linux/mount.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/tracehook.h>
  17 #include <linux/personality.h>
  18 #include <linux/xattr.h>
  19
  20 #include "include/audit.h"
  21 #include "include/apparmorfs.h"
  22 #include "include/cred.h"
  23 #include "include/domain.h"
  24 #include "include/file.h"
  25 #include "include/ipc.h"
  26 #include "include/match.h"
  27 #include "include/path.h"
  28 #include "include/policy.h"
  29 #include "include/policy_ns.h"
  30
  31 /**
  32  * aa_free_domain_entries - free entries in a domain table
  33  * @domain: the domain table to free  (MAYBE NULL)
  34  */
  35 void aa_free_domain_entries(struct aa_domain *domain)
  36 {
  37         int i;
  38         if (domain) {
  39                 if (!domain->table)
  40                         return;
  41
  42                 for (i = 0; i < domain->size; i++)
  43                         kfree_sensitive(domain->table[i]);
  44                 kfree_sensitive(domain->table);
  45                 domain->table = NULL;
  46         }
  47 }
  48
  49 /**
  50  * may_change_ptraced_domain - check if can change profile on ptraced task
  51  * @to_label: profile to change to  (NOT NULL)
  52  * @info: message if there is an error
  53  *
  54  * Check if current is ptraced and if so if the tracing task is allowed
  55  * to trace the new domain
  56  *
  57  * Returns: %0 or error if change not allowed
  58  */
  59 static int may_change_ptraced_domain(struct aa_label *to_label,
  60                                      const char **info)
  61 {
  62         struct task_struct *tracer;
  63         struct aa_label *tracerl = NULL;
  64         int error = 0;
  65
  66         rcu_read_lock();
  67         tracer = ptrace_parent(current);
  68         if (tracer)
  69                 /* released below */
  70                 tracerl = aa_get_task_label(tracer);
  71
  72         /* not ptraced */
  73         if (!tracer || unconfined(tracerl))
  74                 goto out;
  75
  76         error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
  77
  78 out:
  79         rcu_read_unlock();
  80         aa_put_label(tracerl);
  81
  82         if (error)
  83                 *info = "ptrace prevents transition";
  84         return error;
  85 }
  86
  87 /**** TODO: dedup to aa_label_match - needs perm and dfa, merging
  88  * specifically this is an exact copy of aa_label_match except
  89  * aa_compute_perms is replaced with aa_compute_fperms
  90  * and policy.dfa with file.dfa
  91  ****/
  92 /* match a profile and its associated ns component if needed
  93  * Assumes visibility test has already been done.
  94  * If a subns profile is not to be matched should be prescreened with
  95  * visibility test.
  96  */
  97 static inline unsigned int match_component(struct aa_profile *profile,
  98                                            struct aa_profile *tp,
  99                                            bool stack, unsigned int state)
 100 {
 101         const char *ns_name;
 102
 103         if (stack)
 104                 state = aa_dfa_match(profile->file.dfa, state, "&");
 105         if (profile->ns == tp->ns)
 106                 return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 107
 108         /* try matching with namespace name and then profile */
 109         ns_name = aa_ns_name(profile->ns, tp->ns, true);
 110         state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 111         state = aa_dfa_match(profile->file.dfa, state, ns_name);
 112         state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
 113         return aa_dfa_match(profile->file.dfa, state, tp->base.hname);
 114 }
 115
 116 /**
 117  * label_compound_match - find perms for full compound label
 118  * @profile: profile to find perms for
 119  * @label: label to check access permissions for
 120  * @stack: whether this is a stacking request
 121  * @start: state to start match in
 122  * @subns: whether to do permission checks on components in a subns
 123  * @request: permissions to request
 124  * @perms: perms struct to set
 125  *
 126  * Returns: 0 on success else ERROR
 127  *
 128  * For the label A//&B//&C this does the perm match for A//&B//&C
 129  * @perms should be preinitialized with allperms OR a previous permission
 130  *        check to be stacked.
 131  */
 132 static int label_compound_match(struct aa_profile *profile,
 133                                 struct aa_label *label, bool stack,
 134                                 unsigned int state, bool subns, u32 request,
 135                                 struct aa_perms *perms)
 136 {
 137         struct aa_profile *tp;
 138         struct label_it i;
 139         struct path_cond cond = { };
 140
 141         /* find first subcomponent that is visible */
 142         label_for_each(i, label, tp) {
 143                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 144                         continue;
 145                 state = match_component(profile, tp, stack, state);
 146                 if (!state)
 147                         goto fail;
 148                 goto next;
 149         }
 150
 151         /* no component visible */
 152         *perms = allperms;
 153         return 0;
 154
 155 next:
 156         label_for_each_cont(i, label, tp) {
 157                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 158                         continue;
 159                 state = aa_dfa_match(profile->file.dfa, state, "//&");
 160                 state = match_component(profile, tp, false, state);
 161                 if (!state)
 162                         goto fail;
 163         }
 164         *perms = aa_compute_fperms(profile->file.dfa, state, &cond);
 165         aa_apply_modes_to_perms(profile, perms);
 166         if ((perms->allow & request) != request)
 167                 return -EACCES;
 168
 169         return 0;
 170
 171 fail:
 172         *perms = nullperms;
 173         return -EACCES;
 174 }
 175
 176 /**
 177  * label_components_match - find perms for all subcomponents of a label
 178  * @profile: profile to find perms for
 179  * @label: label to check access permissions for
 180  * @stack: whether this is a stacking request
 181  * @start: state to start match in
 182  * @subns: whether to do permission checks on components in a subns
 183  * @request: permissions to request
 184  * @perms: an initialized perms struct to add accumulation to
 185  *
 186  * Returns: 0 on success else ERROR
 187  *
 188  * For the label A//&B//&C this does the perm match for each of A and B and C
 189  * @perms should be preinitialized with allperms OR a previous permission
 190  *        check to be stacked.
 191  */
 192 static int label_components_match(struct aa_profile *profile,
 193                                   struct aa_label *label, bool stack,
 194                                   unsigned int start, bool subns, u32 request,
 195                                   struct aa_perms *perms)
 196 {
 197         struct aa_profile *tp;
 198         struct label_it i;
 199         struct aa_perms tmp;
 200         struct path_cond cond = { };
 201         unsigned int state = 0;
 202
 203         /* find first subcomponent to test */
 204         label_for_each(i, label, tp) {
 205                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 206                         continue;
 207                 state = match_component(profile, tp, stack, start);
 208                 if (!state)
 209                         goto fail;
 210                 goto next;
 211         }
 212
 213         /* no subcomponents visible - no change in perms */
 214         return 0;
 215
 216 next:
 217         tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 218         aa_apply_modes_to_perms(profile, &tmp);
 219         aa_perms_accum(perms, &tmp);
 220         label_for_each_cont(i, label, tp) {
 221                 if (!aa_ns_visible(profile->ns, tp->ns, subns))
 222                         continue;
 223                 state = match_component(profile, tp, stack, start);
 224                 if (!state)
 225                         goto fail;
 226                 tmp = aa_compute_fperms(profile->file.dfa, state, &cond);
 227                 aa_apply_modes_to_perms(profile, &tmp);
 228                 aa_perms_accum(perms, &tmp);
 229         }
 230
 231         if ((perms->allow & request) != request)
 232                 return -EACCES;
 233
 234         return 0;
 235
 236 fail:
 237         *perms = nullperms;
 238         return -EACCES;
 239 }
 240
 241 /**
 242  * label_match - do a multi-component label match
 243  * @profile: profile to match against (NOT NULL)
 244  * @label: label to match (NOT NULL)
 245  * @stack: whether this is a stacking request
 246  * @state: state to start in
 247  * @subns: whether to match subns components
 248  * @request: permission request
 249  * @perms: Returns computed perms (NOT NULL)
 250  *
 251  * Returns: the state the match finished in, may be the none matching state
 252  */
 253 static int label_match(struct aa_profile *profile, struct aa_label *label,
 254                        bool stack, unsigned int state, bool subns, u32 request,
 255                        struct aa_perms *perms)
 256 {
 257         int error;
 258
 259         *perms = nullperms;
 260         error = label_compound_match(profile, label, stack, state, subns,
 261                                      request, perms);
 262         if (!error)
 263                 return error;
 264
 265         *perms = allperms;
 266         return label_components_match(profile, label, stack, state, subns,
 267                                       request, perms);
 268 }
 269
 270 /******* end TODO: dedup *****/
 271
 272 /**
 273  * change_profile_perms - find permissions for change_profile
 274  * @profile: the current profile  (NOT NULL)
 275  * @target: label to transition to (NOT NULL)
 276  * @stack: whether this is a stacking request
 277  * @request: requested perms
 278  * @start: state to start matching in
 279  *
 280  *
 281  * Returns: permission set
 282  *
 283  * currently only matches full label A//&B//&C or individual components A, B, C
 284  * not arbitrary combinations. Eg. A//&B, C
 285  */
 286 static int change_profile_perms(struct aa_profile *profile,
 287                                 struct aa_label *target, bool stack,
 288                                 u32 request, unsigned int start,
 289                                 struct aa_perms *perms)
 290 {
 291         if (profile_unconfined(profile)) {
 292                 perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
 293                 perms->audit = perms->quiet = perms->kill = 0;
 294                 return 0;
 295         }
 296
 297         /* TODO: add profile in ns screening */
 298         return label_match(profile, target, stack, start, true, request, perms);
 299 }
 300
 301 /**
 302  * aa_xattrs_match - check whether a file matches the xattrs defined in profile
 303  * @bprm: binprm struct for the process to validate
 304  * @profile: profile to match against (NOT NULL)
 305  * @state: state to start match in
 306  *
 307  * Returns: number of extended attributes that matched, or < 0 on error
 308  */
 309 static int aa_xattrs_match(const struct linux_binprm *bprm,
 310                            struct aa_profile *profile, unsigned int state)
 311 {
 312         int i;
 313         ssize_t size;
 314         struct dentry *d;
 315         char *value = NULL;
 316         int value_size = 0, ret = profile->xattr_count;
 317
 318         if (!bprm || !profile->xattr_count)
 319                 return 0;
 320         might_sleep();
 321
 322         /* transition from exec match to xattr set */
 323         state = aa_dfa_outofband_transition(profile->xmatch, state);
 324         d = bprm->file->f_path.dentry;
 325
 326         for (i = 0; i < profile->xattr_count; i++) {
 327                 size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
 328                                           value_size, GFP_KERNEL);
 329                 if (size >= 0) {
 330                         u32 perm;
 331
 332                         /*
 333                          * Check the xattr presence before value. This ensure
 334                          * that not present xattr can be distinguished from a 0
 335                          * length value or rule that matches any value
 336                          */
 337                         state = aa_dfa_null_transition(profile->xmatch, state);
 338                         /* Check xattr value */
 339                         state = aa_dfa_match_len(profile->xmatch, state, value,
 340                                                  size);
 341                         perm = dfa_user_allow(profile->xmatch, state);
 342                         if (!(perm & MAY_EXEC)) {
 343                                 ret = -EINVAL;
 344                                 goto out;
 345                         }
 346                 }
 347                 /* transition to next element */
 348                 state = aa_dfa_outofband_transition(profile->xmatch, state);
 349                 if (size < 0) {
 350                         /*
 351                          * No xattr match, so verify if transition to
 352                          * next element was valid. IFF so the xattr
 353                          * was optional.
 354                          */
 355                         if (!state) {
 356                                 ret = -EINVAL;
 357                                 goto out;
 358                         }
 359                         /* don't count missing optional xattr as matched */
 360                         ret--;
 361                 }
 362         }
 363
 364 out:
 365         kfree(value);
 366         return ret;
 367 }
 368
 369 /**
 370  * find_attach - do attachment search for unconfined processes
 371  * @bprm - binprm structure of transitioning task
 372  * @ns: the current namespace  (NOT NULL)
 373  * @head - profile list to walk  (NOT NULL)
 374  * @name - to match against  (NOT NULL)
 375  * @info - info message if there was an error (NOT NULL)
 376  *
 377  * Do a linear search on the profiles in the list.  There is a matching
 378  * preference where an exact match is preferred over a name which uses
 379  * expressions to match, and matching expressions with the greatest
 380  * xmatch_len are preferred.
 381  *
 382  * Requires: @head not be shared or have appropriate locks held
 383  *
 384  * Returns: label or NULL if no match found
 385  */
 386 static struct aa_label *find_attach(const struct linux_binprm *bprm,
 387                                     struct aa_ns *ns, struct list_head *head,
 388                                     const char *name, const char **info)
 389 {
 390         int candidate_len = 0, candidate_xattrs = 0;
 391         bool conflict = false;
 392         struct aa_profile *profile, *candidate = NULL;
 393
 394         AA_BUG(!name);
 395         AA_BUG(!head);
 396
 397         rcu_read_lock();
 398 restart:
 399         list_for_each_entry_rcu(profile, head, base.list) {
 400                 if (profile->label.flags & FLAG_NULL &&
 401                     &profile->label == ns_unconfined(profile->ns))
 402                         continue;
 403
 404                 /* Find the "best" matching profile. Profiles must
 405                  * match the path and extended attributes (if any)
 406                  * associated with the file. A more specific path
 407                  * match will be preferred over a less specific one,
 408                  * and a match with more matching extended attributes
 409                  * will be preferred over one with fewer. If the best
 410                  * match has both the same level of path specificity
 411                  * and the same number of matching extended attributes
 412                  * as another profile, signal a conflict and refuse to
 413                  * match.
 414                  */
 415                 if (profile->xmatch) {
 416                         unsigned int state, count;
 417                         u32 perm;
 418
 419                         state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
 420                                                  name, &count);
 421                         perm = dfa_user_allow(profile->xmatch, state);
 422                         /* any accepting state means a valid match. */
 423                         if (perm & MAY_EXEC) {
 424                                 int ret = 0;
 425
 426                                 if (count < candidate_len)
 427                                         continue;
 428
 429                                 if (bprm && profile->xattr_count) {
 430                                         long rev = READ_ONCE(ns->revision);
 431
 432                                         if (!aa_get_profile_not0(profile))
 433                                                 goto restart;
 434                                         rcu_read_unlock();
 435                                         ret = aa_xattrs_match(bprm, profile,
 436                                                               state);
 437                                         rcu_read_lock();
 438                                         aa_put_profile(profile);
 439                                         if (rev !=
 440                                             READ_ONCE(ns->revision))
 441                                                 /* policy changed */
 442                                                 goto restart;
 443                                         /*
 444                                          * Fail matching if the xattrs don't
 445                                          * match
 446                                          */
 447                                         if (ret < 0)
 448                                                 continue;
 449                                 }
 450                                 /*
 451                                  * TODO: allow for more flexible best match
 452                                  *
 453                                  * The new match isn't more specific
 454                                  * than the current best match
 455                                  */
 456                                 if (count == candidate_len &&
 457                                     ret <= candidate_xattrs) {
 458                                         /* Match is equivalent, so conflict */
 459                                         if (ret == candidate_xattrs)
 460                                                 conflict = true;
 461                                         continue;
 462                                 }
 463
 464                                 /* Either the same length with more matching
 465                                  * xattrs, or a longer match
 466                                  */
 467                                 candidate = profile;
 468                                 candidate_len = profile->xmatch_len;
 469                                 candidate_xattrs = ret;
 470                                 conflict = false;
 471                         }
 472                 } else if (!strcmp(profile->base.name, name)) {
 473                         /*
 474                          * old exact non-re match, without conditionals such
 475                          * as xattrs. no more searching required
 476                          */
 477                         candidate = profile;
 478                         goto out;
 479                 }
 480         }
 481
 482         if (!candidate || conflict) {
 483                 if (conflict)
 484                         *info = "conflicting profile attachments";
 485                 rcu_read_unlock();
 486                 return NULL;
 487         }
 488
 489 out:
 490         candidate = aa_get_newest_profile(candidate);
 491         rcu_read_unlock();
 492
 493         return &candidate->label;
 494 }
 495
 496 static const char *next_name(int xtype, const char *name)
 497 {
 498         return NULL;
 499 }
 500
 501 /**
 502  * x_table_lookup - lookup an x transition name via transition table
 503  * @profile: current profile (NOT NULL)
 504  * @xindex: index into x transition table
 505  * @name: returns: name tested to find label (NOT NULL)
 506  *
 507  * Returns: refcounted label, or NULL on failure (MAYBE NULL)
 508  */
 509 struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
 510                                 const char **name)
 511 {
 512         struct aa_label *label = NULL;
 513         u32 xtype = xindex & AA_X_TYPE_MASK;
 514         int index = xindex & AA_X_INDEX_MASK;
 515
 516         AA_BUG(!name);
 517
 518         /* index is guaranteed to be in range, validated at load time */
 519         /* TODO: move lookup parsing to unpack time so this is a straight
 520          *       index into the resultant label
 521          */
 522         for (*name = profile->file.trans.table[index]; !label && *name;
 523              *name = next_name(xtype, *name)) {
 524                 if (xindex & AA_X_CHILD) {
 525                         struct aa_profile *new_profile;
 526                         /* release by caller */
 527                         new_profile = aa_find_child(profile, *name);
 528                         if (new_profile)
 529                                 label = &new_profile->label;
 530                         continue;
 531                 }
 532                 label = aa_label_parse(&profile->label, *name, GFP_KERNEL,
 533                                        true, false);
 534                 if (IS_ERR(label))
 535                         label = NULL;
 536         }
 537
 538         /* released by caller */
 539
 540         return label;
 541 }
 542
 543 /**
 544  * x_to_label - get target label for a given xindex
 545  * @profile: current profile  (NOT NULL)
 546  * @bprm: binprm structure of transitioning task
 547  * @name: name to lookup (NOT NULL)
 548  * @xindex: index into x transition table
 549  * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
 550  *
 551  * find label for a transition index
 552  *
 553  * Returns: refcounted label or NULL if not found available
 554  */
 555 static struct aa_label *x_to_label(struct aa_profile *profile,
 556                                    const struct linux_binprm *bprm,
 557                                    const char *name, u32 xindex,
 558                                    const char **lookupname,
 559                                    const char **info)
 560 {
 561         struct aa_label *new = NULL;
 562         struct aa_ns *ns = profile->ns;
 563         u32 xtype = xindex & AA_X_TYPE_MASK;
 564         const char *stack = NULL;
 565
 566         switch (xtype) {
 567         case AA_X_NONE:
 568                 /* fail exec unless ix || ux fallback - handled by caller */
 569                 *lookupname = NULL;
 570                 break;
 571         case AA_X_TABLE:
 572                 /* TODO: fix when perm mapping done at unload */
 573                 stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
 574                 if (*stack != '&') {
 575                         /* released by caller */
 576                         new = x_table_lookup(profile, xindex, lookupname);
 577                         stack = NULL;
 578                         break;
 579                 }
 580                 fallthrough;    /* to X_NAME */
 581         case AA_X_NAME:
 582                 if (xindex & AA_X_CHILD)
 583                         /* released by caller */
 584                         new = find_attach(bprm, ns, &profile->base.profiles,
 585                                           name, info);
 586                 else
 587                         /* released by caller */
 588                         new = find_attach(bprm, ns, &ns->base.profiles,
 589                                           name, info);
 590                 *lookupname = name;
 591                 break;
 592         }
 593
 594         if (!new) {
 595                 if (xindex & AA_X_INHERIT) {
 596                         /* (p|c|n)ix - don't change profile but do
 597                          * use the newest version
 598                          */
 599                         *info = "ix fallback";
 600                         /* no profile && no error */
 601                         new = aa_get_newest_label(&profile->label);
 602                 } else if (xindex & AA_X_UNCONFINED) {
 603                         new = aa_get_newest_label(ns_unconfined(profile->ns));
 604                         *info = "ux fallback";
 605                 }
 606         }
 607
 608         if (new && stack) {
 609                 /* base the stack on post domain transition */
 610                 struct aa_label *base = new;
 611
 612                 new = aa_label_parse(base, stack, GFP_KERNEL, true, false);
 613                 if (IS_ERR(new))
 614                         new = NULL;
 615                 aa_put_label(base);
 616         }
 617
 618         /* released by caller */
 619         return new;
 620 }
 621
 622 static struct aa_label *profile_transition(struct aa_profile *profile,
 623                                            const struct linux_binprm *bprm,
 624                                            char *buffer, struct path_cond *cond,
 625                                            bool *secure_exec)
 626 {
 627         struct aa_label *new = NULL;
 628         const char *info = NULL, *name = NULL, *target = NULL;
 629         unsigned int state = profile->file.start;
 630         struct aa_perms perms = {};
 631         bool nonewprivs = false;
 632         int error = 0;
 633
 634         AA_BUG(!profile);
 635         AA_BUG(!bprm);
 636         AA_BUG(!buffer);
 637
 638         error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 639                              &name, &info, profile->disconnected);
 640         if (error) {
 641                 if (profile_unconfined(profile) ||
 642                     (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 643                         AA_DEBUG("name lookup ix on error");
 644                         error = 0;
 645                         new = aa_get_newest_label(&profile->label);
 646                 }
 647                 name = bprm->filename;
 648                 goto audit;
 649         }
 650
 651         if (profile_unconfined(profile)) {
 652                 new = find_attach(bprm, profile->ns,
 653                                   &profile->ns->base.profiles, name, &info);
 654                 if (new) {
 655                         AA_DEBUG("unconfined attached to new label");
 656                         return new;
 657                 }
 658                 AA_DEBUG("unconfined exec no attachment");
 659                 return aa_get_newest_label(&profile->label);
 660         }
 661
 662         /* find exec permissions for name */
 663         state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
 664         if (perms.allow & MAY_EXEC) {
 665                 /* exec permission determine how to transition */
 666                 new = x_to_label(profile, bprm, name, perms.xindex, &target,
 667                                  &info);
 668                 if (new && new->proxy == profile->label.proxy && info) {
 669                         /* hack ix fallback - improve how this is detected */
 670                         goto audit;
 671                 } else if (!new) {
 672                         error = -EACCES;
 673                         info = "profile transition not found";
 674                         /* remove MAY_EXEC to audit as failure */
 675                         perms.allow &= ~MAY_EXEC;
 676                 }
 677         } else if (COMPLAIN_MODE(profile)) {
 678                 /* no exec permission - learning mode */
 679                 struct aa_profile *new_profile = NULL;
 680
 681                 new_profile = aa_new_null_profile(profile, false, name,
 682                                                   GFP_KERNEL);
 683                 if (!new_profile) {
 684                         error = -ENOMEM;
 685                         info = "could not create null profile";
 686                 } else {
 687                         error = -EACCES;
 688                         new = &new_profile->label;
 689                 }
 690                 perms.xindex |= AA_X_UNSAFE;
 691         } else
 692                 /* fail exec */
 693                 error = -EACCES;
 694
 695         if (!new)
 696                 goto audit;
 697
 698
 699         if (!(perms.xindex & AA_X_UNSAFE)) {
 700                 if (DEBUG_ON) {
 701                         dbg_printk("apparmor: scrubbing environment variables"
 702                                    " for %s profile=", name);
 703                         aa_label_printk(new, GFP_KERNEL);
 704                         dbg_printk("\n");
 705                 }
 706                 *secure_exec = true;
 707         }
 708
 709 audit:
 710         aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name, target, new,
 711                       cond->uid, info, error);
 712         if (!new || nonewprivs) {
 713                 aa_put_label(new);
 714                 return ERR_PTR(error);
 715         }
 716
 717         return new;
 718 }
 719
 720 static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
 721                           bool stack, const struct linux_binprm *bprm,
 722                           char *buffer, struct path_cond *cond,
 723                           bool *secure_exec)
 724 {
 725         unsigned int state = profile->file.start;
 726         struct aa_perms perms = {};
 727         const char *xname = NULL, *info = "change_profile onexec";
 728         int error = -EACCES;
 729
 730         AA_BUG(!profile);
 731         AA_BUG(!onexec);
 732         AA_BUG(!bprm);
 733         AA_BUG(!buffer);
 734
 735         if (profile_unconfined(profile)) {
 736                 /* change_profile on exec already granted */
 737                 /*
 738                  * NOTE: Domain transitions from unconfined are allowed
 739                  * even when no_new_privs is set because this aways results
 740                  * in a further reduction of permissions.
 741                  */
 742                 return 0;
 743         }
 744
 745         error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
 746                              &xname, &info, profile->disconnected);
 747         if (error) {
 748                 if (profile_unconfined(profile) ||
 749                     (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
 750                         AA_DEBUG("name lookup ix on error");
 751                         error = 0;
 752                 }
 753                 xname = bprm->filename;
 754                 goto audit;
 755         }
 756
 757         /* find exec permissions for name */
 758         state = aa_str_perms(profile->file.dfa, state, xname, cond, &perms);
 759         if (!(perms.allow & AA_MAY_ONEXEC)) {
 760                 info = "no change_onexec valid for executable";
 761                 goto audit;
 762         }
 763         /* test if this exec can be paired with change_profile onexec.
 764          * onexec permission is linked to exec with a standard pairing
 765          * exec\0change_profile
 766          */
 767         state = aa_dfa_null_transition(profile->file.dfa, state);
 768         error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
 769                                      state, &perms);
 770         if (error) {
 771                 perms.allow &= ~AA_MAY_ONEXEC;
 772                 goto audit;
 773         }
 774
 775         if (!(perms.xindex & AA_X_UNSAFE)) {
 776                 if (DEBUG_ON) {
 777                         dbg_printk("apparmor: scrubbing environment "
 778                                    "variables for %s label=", xname);
 779                         aa_label_printk(onexec, GFP_KERNEL);
 780                         dbg_printk("\n");
 781                 }
 782                 *secure_exec = true;
 783         }
 784
 785 audit:
 786         return aa_audit_file(profile, &perms, OP_EXEC, AA_MAY_ONEXEC, xname,
 787                              NULL, onexec, cond->uid, info, error);
 788 }
 789
 790 /* ensure none ns domain transitions are correctly applied with onexec */
 791
 792 static struct aa_label *handle_onexec(struct aa_label *label,
 793                                       struct aa_label *onexec, bool stack,
 794                                       const struct linux_binprm *bprm,
 795                                       char *buffer, struct path_cond *cond,
 796                                       bool *unsafe)
 797 {
 798         struct aa_profile *profile;
 799         struct aa_label *new;
 800         int error;
 801
 802         AA_BUG(!label);
 803         AA_BUG(!onexec);
 804         AA_BUG(!bprm);
 805         AA_BUG(!buffer);
 806
 807         if (!stack) {
 808                 error = fn_for_each_in_ns(label, profile,
 809                                 profile_onexec(profile, onexec, stack,
 810                                                bprm, buffer, cond, unsafe));
 811                 if (error)
 812                         return ERR_PTR(error);
 813                 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
 814                                 aa_get_newest_label(onexec),
 815                                 profile_transition(profile, bprm, buffer,
 816                                                    cond, unsafe));
 817
 818         } else {
 819                 /* TODO: determine how much we want to loosen this */
 820                 error = fn_for_each_in_ns(label, profile,
 821                                 profile_onexec(profile, onexec, stack, bprm,
 822                                                buffer, cond, unsafe));
 823                 if (error)
 824                         return ERR_PTR(error);
 825                 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
 826                                 aa_label_merge(&profile->label, onexec,
 827                                                GFP_KERNEL),
 828                                 profile_transition(profile, bprm, buffer,
 829                                                    cond, unsafe));
 830         }
 831
 832         if (new)
 833                 return new;
 834
 835         /* TODO: get rid of GLOBAL_ROOT_UID */
 836         error = fn_for_each_in_ns(label, profile,
 837                         aa_audit_file(profile, &nullperms, OP_CHANGE_ONEXEC,
 838                                       AA_MAY_ONEXEC, bprm->filename, NULL,
 839                                       onexec, GLOBAL_ROOT_UID,
 840                                       "failed to build target label", -ENOMEM));
 841         return ERR_PTR(error);
 842 }
 843
 844 /**
 845  * apparmor_bprm_creds_for_exec - Update the new creds on the bprm struct
 846  * @bprm: binprm for the exec  (NOT NULL)
 847  *
 848  * Returns: %0 or error on failure
 849  *
 850  * TODO: once the other paths are done see if we can't refactor into a fn
 851  */
 852 int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm)
 853 {
 854         struct aa_task_ctx *ctx;
 855         struct aa_label *label, *new = NULL;
 856         struct aa_profile *profile;
 857         char *buffer = NULL;
 858         const char *info = NULL;
 859         int error = 0;
 860         bool unsafe = false;
 861         struct path_cond cond = {
 862                 file_inode(bprm->file)->i_uid,
 863                 file_inode(bprm->file)->i_mode
 864         };
 865
 866         ctx = task_ctx(current);
 867         AA_BUG(!cred_label(bprm->cred));
 868         AA_BUG(!ctx);
 869
 870         label = aa_get_newest_label(cred_label(bprm->cred));
 871
 872         /*
 873          * Detect no new privs being set, and store the label it
 874          * occurred under. Ideally this would happen when nnp
 875          * is set but there isn't a good way to do that yet.
 876          *
 877          * Testing for unconfined must be done before the subset test
 878          */
 879         if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
 880             !ctx->nnp)
 881                 ctx->nnp = aa_get_label(label);
 882
 883         /* buffer freed below, name is pointer into buffer */
 884         buffer = aa_get_buffer(false);
 885         if (!buffer) {
 886                 error = -ENOMEM;
 887                 goto done;
 888         }
 889
 890         /* Test for onexec first as onexec override other x transitions. */
 891         if (ctx->onexec)
 892                 new = handle_onexec(label, ctx->onexec, ctx->token,
 893                                     bprm, buffer, &cond, &unsafe);
 894         else
 895                 new = fn_label_build(label, profile, GFP_KERNEL,
 896                                 profile_transition(profile, bprm, buffer,
 897                                                    &cond, &unsafe));
 898
 899         AA_BUG(!new);
 900         if (IS_ERR(new)) {
 901                 error = PTR_ERR(new);
 902                 goto done;
 903         } else if (!new) {
 904                 error = -ENOMEM;
 905                 goto done;
 906         }
 907
 908         /* Policy has specified a domain transitions. If no_new_privs and
 909          * confined ensure the transition is to confinement that is subset
 910          * of the confinement when the task entered no new privs.
 911          *
 912          * NOTE: Domain transitions from unconfined and to stacked
 913          * subsets are allowed even when no_new_privs is set because this
 914          * aways results in a further reduction of permissions.
 915          */
 916         if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
 917             !unconfined(label) &&
 918             !aa_label_is_unconfined_subset(new, ctx->nnp)) {
 919                 error = -EPERM;
 920                 info = "no new privs";
 921                 goto audit;
 922         }
 923
 924         if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 925                 /* FIXME: currently don't mediate shared state */
 926                 ;
 927         }
 928
 929         if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
 930                 /* TODO: test needs to be profile of label to new */
 931                 error = may_change_ptraced_domain(new, &info);
 932                 if (error)
 933                         goto audit;
 934         }
 935
 936         if (unsafe) {
 937                 if (DEBUG_ON) {
 938                         dbg_printk("scrubbing environment variables for %s "
 939                                    "label=", bprm->filename);
 940                         aa_label_printk(new, GFP_KERNEL);
 941                         dbg_printk("\n");
 942                 }
 943                 bprm->secureexec = 1;
 944         }
 945
 946         if (label->proxy != new->proxy) {
 947                 /* when transitioning clear unsafe personality bits */
 948                 if (DEBUG_ON) {
 949                         dbg_printk("apparmor: clearing unsafe personality "
 950                                    "bits. %s label=", bprm->filename);
 951                         aa_label_printk(new, GFP_KERNEL);
 952                         dbg_printk("\n");
 953                 }
 954                 bprm->per_clear |= PER_CLEAR_ON_SETID;
 955         }
 956         aa_put_label(cred_label(bprm->cred));
 957         /* transfer reference, released when cred is freed */
 958         set_cred_label(bprm->cred, new);
 959
 960 done:
 961         aa_put_label(label);
 962         aa_put_buffer(buffer);
 963
 964         return error;
 965
 966 audit:
 967         error = fn_for_each(label, profile,
 968                         aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
 969                                       bprm->filename, NULL, new,
 970                                       file_inode(bprm->file)->i_uid, info,
 971                                       error));
 972         aa_put_label(new);
 973         goto done;
 974 }
 975
 976 /*
 977  * Functions for self directed profile change
 978  */
 979
 980
 981 /* helper fn for change_hat
 982  *
 983  * Returns: label for hat transition OR ERR_PTR.  Does NOT return NULL
 984  */
 985 static struct aa_label *build_change_hat(struct aa_profile *profile,
 986                                          const char *name, bool sibling)
 987 {
 988         struct aa_profile *root, *hat = NULL;
 989         const char *info = NULL;
 990         int error = 0;
 991
 992         if (sibling && PROFILE_IS_HAT(profile)) {
 993                 root = aa_get_profile_rcu(&profile->parent);
 994         } else if (!sibling && !PROFILE_IS_HAT(profile)) {
 995                 root = aa_get_profile(profile);
 996         } else {
 997                 info = "conflicting target types";
 998                 error = -EPERM;
 999                 goto audit;
1000         }
1001
1002         hat = aa_find_child(root, name);
1003         if (!hat) {
1004                 error = -ENOENT;
1005                 if (COMPLAIN_MODE(profile)) {
1006                         hat = aa_new_null_profile(profile, true, name,
1007                                                   GFP_KERNEL);
1008                         if (!hat) {
1009                                 info = "failed null profile create";
1010                                 error = -ENOMEM;
1011                         }
1012                 }
1013         }
1014         aa_put_profile(root);
1015
1016 audit:
1017         aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
1018                       name, hat ? hat->base.hname : NULL,
1019                       hat ? &hat->label : NULL, GLOBAL_ROOT_UID, info,
1020                       error);
1021         if (!hat || (error && error != -ENOENT))
1022                 return ERR_PTR(error);
1023         /* if hat && error - complain mode, already audited and we adjust for
1024          * complain mode allow by returning hat->label
1025          */
1026         return &hat->label;
1027 }
1028
1029 /* helper fn for changing into a hat
1030  *
1031  * Returns: label for hat transition or ERR_PTR. Does not return NULL
1032  */
1033 static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
1034                                    int count, int flags)
1035 {
1036         struct aa_profile *profile, *root, *hat = NULL;
1037         struct aa_label *new;
1038         struct label_it it;
1039         bool sibling = false;
1040         const char *name, *info = NULL;
1041         int i, error;
1042
1043         AA_BUG(!label);
1044         AA_BUG(!hats);
1045         AA_BUG(count < 1);
1046
1047         if (PROFILE_IS_HAT(labels_profile(label)))
1048                 sibling = true;
1049
1050         /*find first matching hat */
1051         for (i = 0; i < count && !hat; i++) {
1052                 name = hats[i];
1053                 label_for_each_in_ns(it, labels_ns(label), label, profile) {
1054                         if (sibling && PROFILE_IS_HAT(profile)) {
1055                                 root = aa_get_profile_rcu(&profile->parent);
1056                         } else if (!sibling && !PROFILE_IS_HAT(profile)) {
1057                                 root = aa_get_profile(profile);
1058                         } else {        /* conflicting change type */
1059                                 info = "conflicting targets types";
1060                                 error = -EPERM;
1061                                 goto fail;
1062                         }
1063                         hat = aa_find_child(root, name);
1064                         aa_put_profile(root);
1065                         if (!hat) {
1066                                 if (!COMPLAIN_MODE(profile))
1067                                         goto outer_continue;
1068                                 /* complain mode succeed as if hat */
1069                         } else if (!PROFILE_IS_HAT(hat)) {
1070                                 info = "target not hat";
1071                                 error = -EPERM;
1072                                 aa_put_profile(hat);
1073                                 goto fail;
1074                         }
1075                         aa_put_profile(hat);
1076                 }
1077                 /* found a hat for all profiles in ns */
1078                 goto build;
1079 outer_continue:
1080         ;
1081         }
1082         /* no hats that match, find appropriate error
1083          *
1084          * In complain mode audit of the failure is based off of the first
1085          * hat supplied.  This is done due how userspace interacts with
1086          * change_hat.
1087          */
1088         name = NULL;
1089         label_for_each_in_ns(it, labels_ns(label), label, profile) {
1090                 if (!list_empty(&profile->base.profiles)) {
1091                         info = "hat not found";
1092                         error = -ENOENT;
1093                         goto fail;
1094                 }
1095         }
1096         info = "no hats defined";
1097         error = -ECHILD;
1098
1099 fail:
1100         label_for_each_in_ns(it, labels_ns(label), label, profile) {
1101                 /*
1102                  * no target as it has failed to be found or built
1103                  *
1104                  * change_hat uses probing and should not log failures
1105                  * related to missing hats
1106                  */
1107                 /* TODO: get rid of GLOBAL_ROOT_UID */
1108                 if (count > 1 || COMPLAIN_MODE(profile)) {
1109                         aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
1110                                       AA_MAY_CHANGEHAT, name, NULL, NULL,
1111                                       GLOBAL_ROOT_UID, info, error);
1112                 }
1113         }
1114         return ERR_PTR(error);
1115
1116 build:
1117         new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1118                                    build_change_hat(profile, name, sibling),
1119                                    aa_get_label(&profile->label));
1120         if (!new) {
1121                 info = "label build failed";
1122                 error = -ENOMEM;
1123                 goto fail;
1124         } /* else if (IS_ERR) build_change_hat has logged error so return new */
1125
1126         return new;
1127 }
1128
1129 /**
1130  * aa_change_hat - change hat to/from subprofile
1131  * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
1132  * @count: number of hat names in @hats
1133  * @token: magic value to validate the hat change
1134  * @flags: flags affecting behavior of the change
1135  *
1136  * Returns %0 on success, error otherwise.
1137  *
1138  * Change to the first profile specified in @hats that exists, and store
1139  * the @hat_magic in the current task context.  If the count == 0 and the
1140  * @token matches that stored in the current task context, return to the
1141  * top level profile.
1142  *
1143  * change_hat only applies to profiles in the current ns, and each profile
1144  * in the ns must make the same transition otherwise change_hat will fail.
1145  */
1146 int aa_change_hat(const char *hats[], int count, u64 token, int flags)
1147 {
1148         const struct cred *cred;
1149         struct aa_task_ctx *ctx = task_ctx(current);
1150         struct aa_label *label, *previous, *new = NULL, *target = NULL;
1151         struct aa_profile *profile;
1152         struct aa_perms perms = {};
1153         const char *info = NULL;
1154         int error = 0;
1155
1156         /* released below */
1157         cred = get_current_cred();
1158         label = aa_get_newest_cred_label(cred);
1159         previous = aa_get_newest_label(ctx->previous);
1160
1161         /*
1162          * Detect no new privs being set, and store the label it
1163          * occurred under. Ideally this would happen when nnp
1164          * is set but there isn't a good way to do that yet.
1165          *
1166          * Testing for unconfined must be done before the subset test
1167          */
1168         if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1169                 ctx->nnp = aa_get_label(label);
1170
1171         if (unconfined(label)) {
1172                 info = "unconfined can not change_hat";
1173                 error = -EPERM;
1174                 goto fail;
1175         }
1176
1177         if (count) {
1178                 new = change_hat(label, hats, count, flags);
1179                 AA_BUG(!new);
1180                 if (IS_ERR(new)) {
1181                         error = PTR_ERR(new);
1182                         new = NULL;
1183                         /* already audited */
1184                         goto out;
1185                 }
1186
1187                 error = may_change_ptraced_domain(new, &info);
1188                 if (error)
1189                         goto fail;
1190
1191                 /*
1192                  * no new privs prevents domain transitions that would
1193                  * reduce restrictions.
1194                  */
1195                 if (task_no_new_privs(current) && !unconfined(label) &&
1196                     !aa_label_is_unconfined_subset(new, ctx->nnp)) {
1197                         /* not an apparmor denial per se, so don't log it */
1198                         AA_DEBUG("no_new_privs - change_hat denied");
1199                         error = -EPERM;
1200                         goto out;
1201                 }
1202
1203                 if (flags & AA_CHANGE_TEST)
1204                         goto out;
1205
1206                 target = new;
1207                 error = aa_set_current_hat(new, token);
1208                 if (error == -EACCES)
1209                         /* kill task in case of brute force attacks */
1210                         goto kill;
1211         } else if (previous && !(flags & AA_CHANGE_TEST)) {
1212                 /*
1213                  * no new privs prevents domain transitions that would
1214                  * reduce restrictions.
1215                  */
1216                 if (task_no_new_privs(current) && !unconfined(label) &&
1217                     !aa_label_is_unconfined_subset(previous, ctx->nnp)) {
1218                         /* not an apparmor denial per se, so don't log it */
1219                         AA_DEBUG("no_new_privs - change_hat denied");
1220                         error = -EPERM;
1221                         goto out;
1222                 }
1223
1224                 /* Return to saved label.  Kill task if restore fails
1225                  * to avoid brute force attacks
1226                  */
1227                 target = previous;
1228                 error = aa_restore_previous_label(token);
1229                 if (error) {
1230                         if (error == -EACCES)
1231                                 goto kill;
1232                         goto fail;
1233                 }
1234         } /* else ignore @flags && restores when there is no saved profile */
1235
1236 out:
1237         aa_put_label(new);
1238         aa_put_label(previous);
1239         aa_put_label(label);
1240         put_cred(cred);
1241
1242         return error;
1243
1244 kill:
1245         info = "failed token match";
1246         perms.kill = AA_MAY_CHANGEHAT;
1247
1248 fail:
1249         fn_for_each_in_ns(label, profile,
1250                 aa_audit_file(profile, &perms, OP_CHANGE_HAT,
1251                               AA_MAY_CHANGEHAT, NULL, NULL, target,
1252                               GLOBAL_ROOT_UID, info, error));
1253
1254         goto out;
1255 }
1256
1257
1258 static int change_profile_perms_wrapper(const char *op, const char *name,
1259                                         struct aa_profile *profile,
1260                                         struct aa_label *target, bool stack,
1261                                         u32 request, struct aa_perms *perms)
1262 {
1263         const char *info = NULL;
1264         int error = 0;
1265
1266         if (!error)
1267                 error = change_profile_perms(profile, target, stack, request,
1268                                              profile->file.start, perms);
1269         if (error)
1270                 error = aa_audit_file(profile, perms, op, request, name,
1271                                       NULL, target, GLOBAL_ROOT_UID, info,
1272                                       error);
1273
1274         return error;
1275 }
1276
1277 /**
1278  * aa_change_profile - perform a one-way profile transition
1279  * @fqname: name of profile may include namespace (NOT NULL)
1280  * @onexec: whether this transition is to take place immediately or at exec
1281  * @flags: flags affecting change behavior
1282  *
1283  * Change to new profile @name.  Unlike with hats, there is no way
1284  * to change back.  If @name isn't specified the current profile name is
1285  * used.
1286  * If @onexec then the transition is delayed until
1287  * the next exec.
1288  *
1289  * Returns %0 on success, error otherwise.
1290  */
1291 int aa_change_profile(const char *fqname, int flags)
1292 {
1293         struct aa_label *label, *new = NULL, *target = NULL;
1294         struct aa_profile *profile;
1295         struct aa_perms perms = {};
1296         const char *info = NULL;
1297         const char *auditname = fqname;         /* retain leading & if stack */
1298         bool stack = flags & AA_CHANGE_STACK;
1299         struct aa_task_ctx *ctx = task_ctx(current);
1300         int error = 0;
1301         char *op;
1302         u32 request;
1303
1304         label = aa_get_current_label();
1305
1306         /*
1307          * Detect no new privs being set, and store the label it
1308          * occurred under. Ideally this would happen when nnp
1309          * is set but there isn't a good way to do that yet.
1310          *
1311          * Testing for unconfined must be done before the subset test
1312          */
1313         if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
1314                 ctx->nnp = aa_get_label(label);
1315
1316         if (!fqname || !*fqname) {
1317                 aa_put_label(label);
1318                 AA_DEBUG("no profile name");
1319                 return -EINVAL;
1320         }
1321
1322         if (flags & AA_CHANGE_ONEXEC) {
1323                 request = AA_MAY_ONEXEC;
1324                 if (stack)
1325                         op = OP_STACK_ONEXEC;
1326                 else
1327                         op = OP_CHANGE_ONEXEC;
1328         } else {
1329                 request = AA_MAY_CHANGE_PROFILE;
1330                 if (stack)
1331                         op = OP_STACK;
1332                 else
1333                         op = OP_CHANGE_PROFILE;
1334         }
1335
1336         if (*fqname == '&') {
1337                 stack = true;
1338                 /* don't have label_parse() do stacking */
1339                 fqname++;
1340         }
1341         target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
1342         if (IS_ERR(target)) {
1343                 struct aa_profile *tprofile;
1344
1345                 info = "label not found";
1346                 error = PTR_ERR(target);
1347                 target = NULL;
1348                 /*
1349                  * TODO: fixme using labels_profile is not right - do profile
1350                  * per complain profile
1351                  */
1352                 if ((flags & AA_CHANGE_TEST) ||
1353                     !COMPLAIN_MODE(labels_profile(label)))
1354                         goto audit;
1355                 /* released below */
1356                 tprofile = aa_new_null_profile(labels_profile(label), false,
1357                                                fqname, GFP_KERNEL);
1358                 if (!tprofile) {
1359                         info = "failed null profile create";
1360                         error = -ENOMEM;
1361                         goto audit;
1362                 }
1363                 target = &tprofile->label;
1364                 goto check;
1365         }
1366
1367         /*
1368          * self directed transitions only apply to current policy ns
1369          * TODO: currently requiring perms for stacking and straight change
1370          *       stacking doesn't strictly need this. Determine how much
1371          *       we want to loosen this restriction for stacking
1372          *
1373          * if (!stack) {
1374          */
1375         error = fn_for_each_in_ns(label, profile,
1376                         change_profile_perms_wrapper(op, auditname,
1377                                                      profile, target, stack,
1378                                                      request, &perms));
1379         if (error)
1380                 /* auditing done in change_profile_perms_wrapper */
1381                 goto out;
1382
1383         /* } */
1384
1385 check:
1386         /* check if tracing task is allowed to trace target domain */
1387         error = may_change_ptraced_domain(target, &info);
1388         if (error && !fn_for_each_in_ns(label, profile,
1389                                         COMPLAIN_MODE(profile)))
1390                 goto audit;
1391
1392         /* TODO: add permission check to allow this
1393          * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
1394          *      info = "not a single threaded task";
1395          *      error = -EACCES;
1396          *      goto audit;
1397          * }
1398          */
1399         if (flags & AA_CHANGE_TEST)
1400                 goto out;
1401
1402         /* stacking is always a subset, so only check the nonstack case */
1403         if (!stack) {
1404                 new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
1405                                            aa_get_label(target),
1406                                            aa_get_label(&profile->label));
1407                 /*
1408                  * no new privs prevents domain transitions that would
1409                  * reduce restrictions.
1410                  */
1411                 if (task_no_new_privs(current) && !unconfined(label) &&
1412                     !aa_label_is_unconfined_subset(new, ctx->nnp)) {
1413                         /* not an apparmor denial per se, so don't log it */
1414                         AA_DEBUG("no_new_privs - change_hat denied");
1415                         error = -EPERM;
1416                         goto out;
1417                 }
1418         }
1419
1420         if (!(flags & AA_CHANGE_ONEXEC)) {
1421                 /* only transition profiles in the current ns */
1422                 if (stack)
1423                         new = aa_label_merge(label, target, GFP_KERNEL);
1424                 if (IS_ERR_OR_NULL(new)) {
1425                         info = "failed to build target label";
1426                         if (!new)
1427                                 error = -ENOMEM;
1428                         else
1429                                 error = PTR_ERR(new);
1430                         new = NULL;
1431                         perms.allow = 0;
1432                         goto audit;
1433                 }
1434                 error = aa_replace_current_label(new);
1435         } else {
1436                 if (new) {
1437                         aa_put_label(new);
1438                         new = NULL;
1439                 }
1440
1441                 /* full transition will be built in exec path */
1442                 error = aa_set_current_onexec(target, stack);
1443         }
1444
1445 audit:
1446         error = fn_for_each_in_ns(label, profile,
1447                         aa_audit_file(profile, &perms, op, request, auditname,
1448                                       NULL, new ? new : target,
1449                                       GLOBAL_ROOT_UID, info, error));
1450
1451 out:
1452         aa_put_label(new);
1453         aa_put_label(target);
1454         aa_put_label(label);
1455
1456         return error;
1457 }