security/apparmor/domain.c

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