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