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