security/apparmor/mount.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor mediation of files
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2017 Canonical Ltd.
   9  */
  10
  11 #include <linux/fs.h>
  12 #include <linux/mount.h>
  13 #include <linux/namei.h>
  14 #include <uapi/linux/mount.h>
  15
  16 #include "include/apparmor.h"
  17 #include "include/audit.h"
  18 #include "include/cred.h"
  19 #include "include/domain.h"
  20 #include "include/file.h"
  21 #include "include/match.h"
  22 #include "include/mount.h"
  23 #include "include/path.h"
  24 #include "include/policy.h"
  25
  26
  27 static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags)
  28 {
  29         if (flags & MS_RDONLY)
  30                 audit_log_format(ab, "ro");
  31         else
  32                 audit_log_format(ab, "rw");
  33         if (flags & MS_NOSUID)
  34                 audit_log_format(ab, ", nosuid");
  35         if (flags & MS_NODEV)
  36                 audit_log_format(ab, ", nodev");
  37         if (flags & MS_NOEXEC)
  38                 audit_log_format(ab, ", noexec");
  39         if (flags & MS_SYNCHRONOUS)
  40                 audit_log_format(ab, ", sync");
  41         if (flags & MS_REMOUNT)
  42                 audit_log_format(ab, ", remount");
  43         if (flags & MS_MANDLOCK)
  44                 audit_log_format(ab, ", mand");
  45         if (flags & MS_DIRSYNC)
  46                 audit_log_format(ab, ", dirsync");
  47         if (flags & MS_NOSYMFOLLOW)
  48                 audit_log_format(ab, ", nosymfollow");
  49         if (flags & MS_NOATIME)
  50                 audit_log_format(ab, ", noatime");
  51         if (flags & MS_NODIRATIME)
  52                 audit_log_format(ab, ", nodiratime");
  53         if (flags & MS_BIND)
  54                 audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind");
  55         if (flags & MS_MOVE)
  56                 audit_log_format(ab, ", move");
  57         if (flags & MS_SILENT)
  58                 audit_log_format(ab, ", silent");
  59         if (flags & MS_POSIXACL)
  60                 audit_log_format(ab, ", acl");
  61         if (flags & MS_UNBINDABLE)
  62                 audit_log_format(ab, flags & MS_REC ? ", runbindable" :
  63                                  ", unbindable");
  64         if (flags & MS_PRIVATE)
  65                 audit_log_format(ab, flags & MS_REC ? ", rprivate" :
  66                                  ", private");
  67         if (flags & MS_SLAVE)
  68                 audit_log_format(ab, flags & MS_REC ? ", rslave" :
  69                                  ", slave");
  70         if (flags & MS_SHARED)
  71                 audit_log_format(ab, flags & MS_REC ? ", rshared" :
  72                                  ", shared");
  73         if (flags & MS_RELATIME)
  74                 audit_log_format(ab, ", relatime");
  75         if (flags & MS_I_VERSION)
  76                 audit_log_format(ab, ", iversion");
  77         if (flags & MS_STRICTATIME)
  78                 audit_log_format(ab, ", strictatime");
  79         if (flags & MS_NOUSER)
  80                 audit_log_format(ab, ", nouser");
  81 }
  82
  83 /**
  84  * audit_cb - call back for mount specific audit fields
  85  * @ab: audit_buffer  (NOT NULL)
  86  * @va: audit struct to audit values of  (NOT NULL)
  87  */
  88 static void audit_cb(struct audit_buffer *ab, void *va)
  89 {
  90         struct common_audit_data *sa = va;
  91         struct apparmor_audit_data *ad = aad(sa);
  92
  93         if (ad->mnt.type) {
  94                 audit_log_format(ab, " fstype=");
  95                 audit_log_untrustedstring(ab, ad->mnt.type);
  96         }
  97         if (ad->mnt.src_name) {
  98                 audit_log_format(ab, " srcname=");
  99                 audit_log_untrustedstring(ab, ad->mnt.src_name);
 100         }
 101         if (ad->mnt.trans) {
 102                 audit_log_format(ab, " trans=");
 103                 audit_log_untrustedstring(ab, ad->mnt.trans);
 104         }
 105         if (ad->mnt.flags) {
 106                 audit_log_format(ab, " flags=\"");
 107                 audit_mnt_flags(ab, ad->mnt.flags);
 108                 audit_log_format(ab, "\"");
 109         }
 110         if (ad->mnt.data) {
 111                 audit_log_format(ab, " options=");
 112                 audit_log_untrustedstring(ab, ad->mnt.data);
 113         }
 114 }
 115
 116 /**
 117  * audit_mount - handle the auditing of mount operations
 118  * @subj_cred: cred of the subject
 119  * @profile: the profile being enforced  (NOT NULL)
 120  * @op: operation being mediated (NOT NULL)
 121  * @name: name of object being mediated (MAYBE NULL)
 122  * @src_name: src_name of object being mediated (MAYBE_NULL)
 123  * @type: type of filesystem (MAYBE_NULL)
 124  * @trans: name of trans (MAYBE NULL)
 125  * @flags: filesystem independent mount flags
 126  * @data: filesystem mount flags
 127  * @request: permissions requested
 128  * @perms: the permissions computed for the request (NOT NULL)
 129  * @info: extra information message (MAYBE NULL)
 130  * @error: 0 if operation allowed else failure error code
 131  *
 132  * Returns: %0 or error on failure
 133  */
 134 static int audit_mount(const struct cred *subj_cred,
 135                        struct aa_profile *profile, const char *op,
 136                        const char *name, const char *src_name,
 137                        const char *type, const char *trans,
 138                        unsigned long flags, const void *data, u32 request,
 139                        struct aa_perms *perms, const char *info, int error)
 140 {
 141         int audit_type = AUDIT_APPARMOR_AUTO;
 142         DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_MOUNT, op);
 143
 144         if (likely(!error)) {
 145                 u32 mask = perms->audit;
 146
 147                 if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
 148                         mask = 0xffff;
 149
 150                 /* mask off perms that are not being force audited */
 151                 request &= mask;
 152
 153                 if (likely(!request))
 154                         return 0;
 155                 audit_type = AUDIT_APPARMOR_AUDIT;
 156         } else {
 157                 /* only report permissions that were denied */
 158                 request = request & ~perms->allow;
 159
 160                 if (request & perms->kill)
 161                         audit_type = AUDIT_APPARMOR_KILL;
 162
 163                 /* quiet known rejects, assumes quiet and kill do not overlap */
 164                 if ((request & perms->quiet) &&
 165                     AUDIT_MODE(profile) != AUDIT_NOQUIET &&
 166                     AUDIT_MODE(profile) != AUDIT_ALL)
 167                         request &= ~perms->quiet;
 168
 169                 if (!request)
 170                         return error;
 171         }
 172
 173         ad.subj_cred = subj_cred;
 174         ad.name = name;
 175         ad.mnt.src_name = src_name;
 176         ad.mnt.type = type;
 177         ad.mnt.trans = trans;
 178         ad.mnt.flags = flags;
 179         if (data && (perms->audit & AA_AUDIT_DATA))
 180                 ad.mnt.data = data;
 181         ad.info = info;
 182         ad.error = error;
 183
 184         return aa_audit(audit_type, profile, &ad, audit_cb);
 185 }
 186
 187 /**
 188  * match_mnt_flags - Do an ordered match on mount flags
 189  * @dfa: dfa to match against
 190  * @state: state to start in
 191  * @flags: mount flags to match against
 192  *
 193  * Mount flags are encoded as an ordered match. This is done instead of
 194  * checking against a simple bitmask, to allow for logical operations
 195  * on the flags.
 196  *
 197  * Returns: next state after flags match
 198  */
 199 static aa_state_t match_mnt_flags(struct aa_dfa *dfa, aa_state_t state,
 200                                     unsigned long flags)
 201 {
 202         unsigned int i;
 203
 204         for (i = 0; i <= 31 ; ++i) {
 205                 if ((1 << i) & flags)
 206                         state = aa_dfa_next(dfa, state, i + 1);
 207         }
 208
 209         return state;
 210 }
 211
 212 static const char * const mnt_info_table[] = {
 213         "match succeeded",
 214         "failed mntpnt match",
 215         "failed srcname match",
 216         "failed type match",
 217         "failed flags match",
 218         "failed data match",
 219         "failed perms check"
 220 };
 221
 222 /*
 223  * Returns 0 on success else element that match failed in, this is the
 224  * index into the mnt_info_table above
 225  */
 226 static int do_match_mnt(struct aa_policydb *policy, aa_state_t start,
 227                         const char *mntpnt, const char *devname,
 228                         const char *type, unsigned long flags,
 229                         void *data, bool binary, struct aa_perms *perms)
 230 {
 231         aa_state_t state;
 232
 233         AA_BUG(!policy);
 234         AA_BUG(!policy->dfa);
 235         AA_BUG(!policy->perms);
 236         AA_BUG(!perms);
 237
 238         state = aa_dfa_match(policy->dfa, start, mntpnt);
 239         state = aa_dfa_null_transition(policy->dfa, state);
 240         if (!state)
 241                 return 1;
 242
 243         if (devname)
 244                 state = aa_dfa_match(policy->dfa, state, devname);
 245         state = aa_dfa_null_transition(policy->dfa, state);
 246         if (!state)
 247                 return 2;
 248
 249         if (type)
 250                 state = aa_dfa_match(policy->dfa, state, type);
 251         state = aa_dfa_null_transition(policy->dfa, state);
 252         if (!state)
 253                 return 3;
 254
 255         state = match_mnt_flags(policy->dfa, state, flags);
 256         if (!state)
 257                 return 4;
 258         *perms = *aa_lookup_perms(policy, state);
 259         if (perms->allow & AA_MAY_MOUNT)
 260                 return 0;
 261
 262         /* only match data if not binary and the DFA flags data is expected */
 263         if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) {
 264                 state = aa_dfa_null_transition(policy->dfa, state);
 265                 if (!state)
 266                         return 4;
 267
 268                 state = aa_dfa_match(policy->dfa, state, data);
 269                 if (!state)
 270                         return 5;
 271                 *perms = *aa_lookup_perms(policy, state);
 272                 if (perms->allow & AA_MAY_MOUNT)
 273                         return 0;
 274         }
 275
 276         /* failed at perms check, don't confuse with flags match */
 277         return 6;
 278 }
 279
 280
 281 static int path_flags(struct aa_profile *profile, const struct path *path)
 282 {
 283         AA_BUG(!profile);
 284         AA_BUG(!path);
 285
 286         return profile->path_flags |
 287                 (S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0);
 288 }
 289
 290 /**
 291  * match_mnt_path_str - handle path matching for mount
 292  * @subj_cred: cred of confined subject
 293  * @profile: the confining profile
 294  * @mntpath: for the mntpnt (NOT NULL)
 295  * @buffer: buffer to be used to lookup mntpath
 296  * @devname: string for the devname/src_name (MAY BE NULL OR ERRPTR)
 297  * @type: string for the dev type (MAYBE NULL)
 298  * @flags: mount flags to match
 299  * @data: fs mount data (MAYBE NULL)
 300  * @binary: whether @data is binary
 301  * @devinfo: error str if (IS_ERR(@devname))
 302  *
 303  * Returns: 0 on success else error
 304  */
 305 static int match_mnt_path_str(const struct cred *subj_cred,
 306                               struct aa_profile *profile,
 307                               const struct path *mntpath, char *buffer,
 308                               const char *devname, const char *type,
 309                               unsigned long flags, void *data, bool binary,
 310                               const char *devinfo)
 311 {
 312         struct aa_perms perms = { };
 313         const char *mntpnt = NULL, *info = NULL;
 314         struct aa_ruleset *rules = list_first_entry(&profile->rules,
 315                                                     typeof(*rules), list);
 316         int pos, error;
 317
 318         AA_BUG(!profile);
 319         AA_BUG(!mntpath);
 320         AA_BUG(!buffer);
 321
 322         if (!RULE_MEDIATES(rules, AA_CLASS_MOUNT))
 323                 return 0;
 324
 325         error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer,
 326                              &mntpnt, &info, profile->disconnected);
 327         if (error)
 328                 goto audit;
 329         if (IS_ERR(devname)) {
 330                 error = PTR_ERR(devname);
 331                 devname = NULL;
 332                 info = devinfo;
 333                 goto audit;
 334         }
 335
 336         error = -EACCES;
 337         pos = do_match_mnt(rules->policy,
 338                            rules->policy->start[AA_CLASS_MOUNT],
 339                            mntpnt, devname, type, flags, data, binary, &perms);
 340         if (pos) {
 341                 info = mnt_info_table[pos];
 342                 goto audit;
 343         }
 344         error = 0;
 345
 346 audit:
 347         return audit_mount(subj_cred, profile, OP_MOUNT, mntpnt, devname,
 348                            type, NULL,
 349                            flags, data, AA_MAY_MOUNT, &perms, info, error);
 350 }
 351
 352 /**
 353  * match_mnt - handle path matching for mount
 354  * @subj_cred: cred of the subject
 355  * @profile: the confining profile
 356  * @path: for the mntpnt (NOT NULL)
 357  * @buffer: buffer to be used to lookup mntpath
 358  * @devpath: path devname/src_name (MAYBE NULL)
 359  * @devbuffer: buffer to be used to lookup devname/src_name
 360  * @type: string for the dev type (MAYBE NULL)
 361  * @flags: mount flags to match
 362  * @data: fs mount data (MAYBE NULL)
 363  * @binary: whether @data is binary
 364  *
 365  * Returns: 0 on success else error
 366  */
 367 static int match_mnt(const struct cred *subj_cred,
 368                      struct aa_profile *profile, const struct path *path,
 369                      char *buffer, const struct path *devpath, char *devbuffer,
 370                      const char *type, unsigned long flags, void *data,
 371                      bool binary)
 372 {
 373         const char *devname = NULL, *info = NULL;
 374         struct aa_ruleset *rules = list_first_entry(&profile->rules,
 375                                                     typeof(*rules), list);
 376         int error = -EACCES;
 377
 378         AA_BUG(!profile);
 379         AA_BUG(devpath && !devbuffer);
 380
 381         if (!RULE_MEDIATES(rules, AA_CLASS_MOUNT))
 382                 return 0;
 383
 384         if (devpath) {
 385                 error = aa_path_name(devpath, path_flags(profile, devpath),
 386                                      devbuffer, &devname, &info,
 387                                      profile->disconnected);
 388                 if (error)
 389                         devname = ERR_PTR(error);
 390         }
 391
 392         return match_mnt_path_str(subj_cred, profile, path, buffer, devname,
 393                                   type, flags, data, binary, info);
 394 }
 395
 396 int aa_remount(const struct cred *subj_cred,
 397                struct aa_label *label, const struct path *path,
 398                unsigned long flags, void *data)
 399 {
 400         struct aa_profile *profile;
 401         char *buffer = NULL;
 402         bool binary;
 403         int error;
 404
 405         AA_BUG(!label);
 406         AA_BUG(!path);
 407
 408         binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA;
 409
 410         buffer = aa_get_buffer(false);
 411         if (!buffer)
 412                 return -ENOMEM;
 413         error = fn_for_each_confined(label, profile,
 414                         match_mnt(subj_cred, profile, path, buffer, NULL,
 415                                   NULL, NULL,
 416                                   flags, data, binary));
 417         aa_put_buffer(buffer);
 418
 419         return error;
 420 }
 421
 422 int aa_bind_mount(const struct cred *subj_cred,
 423                   struct aa_label *label, const struct path *path,
 424                   const char *dev_name, unsigned long flags)
 425 {
 426         struct aa_profile *profile;
 427         char *buffer = NULL, *old_buffer = NULL;
 428         struct path old_path;
 429         int error;
 430
 431         AA_BUG(!label);
 432         AA_BUG(!path);
 433
 434         if (!dev_name || !*dev_name)
 435                 return -EINVAL;
 436
 437         flags &= MS_REC | MS_BIND;
 438
 439         error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
 440         if (error)
 441                 return error;
 442
 443         buffer = aa_get_buffer(false);
 444         old_buffer = aa_get_buffer(false);
 445         error = -ENOMEM;
 446         if (!buffer || !old_buffer)
 447                 goto out;
 448
 449         error = fn_for_each_confined(label, profile,
 450                         match_mnt(subj_cred, profile, path, buffer, &old_path,
 451                                   old_buffer, NULL, flags, NULL, false));
 452 out:
 453         aa_put_buffer(buffer);
 454         aa_put_buffer(old_buffer);
 455         path_put(&old_path);
 456
 457         return error;
 458 }
 459
 460 int aa_mount_change_type(const struct cred *subj_cred,
 461                          struct aa_label *label, const struct path *path,
 462                          unsigned long flags)
 463 {
 464         struct aa_profile *profile;
 465         char *buffer = NULL;
 466         int error;
 467
 468         AA_BUG(!label);
 469         AA_BUG(!path);
 470
 471         /* These are the flags allowed by do_change_type() */
 472         flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE |
 473                   MS_UNBINDABLE);
 474
 475         buffer = aa_get_buffer(false);
 476         if (!buffer)
 477                 return -ENOMEM;
 478         error = fn_for_each_confined(label, profile,
 479                         match_mnt(subj_cred, profile, path, buffer, NULL,
 480                                   NULL, NULL,
 481                                   flags, NULL, false));
 482         aa_put_buffer(buffer);
 483
 484         return error;
 485 }
 486
 487 int aa_move_mount(const struct cred *subj_cred,
 488                   struct aa_label *label, const struct path *from_path,
 489                   const struct path *to_path)
 490 {
 491         struct aa_profile *profile;
 492         char *to_buffer = NULL, *from_buffer = NULL;
 493         int error;
 494
 495         AA_BUG(!label);
 496         AA_BUG(!from_path);
 497         AA_BUG(!to_path);
 498
 499         to_buffer = aa_get_buffer(false);
 500         from_buffer = aa_get_buffer(false);
 501         error = -ENOMEM;
 502         if (!to_buffer || !from_buffer)
 503                 goto out;
 504
 505         if (!our_mnt(from_path->mnt))
 506                 /* moving a mount detached from the namespace */
 507                 from_path = NULL;
 508         error = fn_for_each_confined(label, profile,
 509                         match_mnt(subj_cred, profile, to_path, to_buffer,
 510                                   from_path, from_buffer,
 511                                   NULL, MS_MOVE, NULL, false));
 512 out:
 513         aa_put_buffer(to_buffer);
 514         aa_put_buffer(from_buffer);
 515
 516         return error;
 517 }
 518
 519 int aa_move_mount_old(const struct cred *subj_cred, struct aa_label *label,
 520                       const struct path *path, const char *orig_name)
 521 {
 522         struct path old_path;
 523         int error;
 524
 525         if (!orig_name || !*orig_name)
 526                 return -EINVAL;
 527         error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path);
 528         if (error)
 529                 return error;
 530
 531         error = aa_move_mount(subj_cred, label, &old_path, path);
 532         path_put(&old_path);
 533
 534         return error;
 535 }
 536
 537 int aa_new_mount(const struct cred *subj_cred, struct aa_label *label,
 538                  const char *dev_name, const struct path *path,
 539                  const char *type, unsigned long flags, void *data)
 540 {
 541         struct aa_profile *profile;
 542         char *buffer = NULL, *dev_buffer = NULL;
 543         bool binary = true;
 544         int error;
 545         int requires_dev = 0;
 546         struct path tmp_path, *dev_path = NULL;
 547
 548         AA_BUG(!label);
 549         AA_BUG(!path);
 550
 551         if (type) {
 552                 struct file_system_type *fstype;
 553
 554                 fstype = get_fs_type(type);
 555                 if (!fstype)
 556                         return -ENODEV;
 557                 binary = fstype->fs_flags & FS_BINARY_MOUNTDATA;
 558                 requires_dev = fstype->fs_flags & FS_REQUIRES_DEV;
 559                 put_filesystem(fstype);
 560
 561                 if (requires_dev) {
 562                         if (!dev_name || !*dev_name)
 563                                 return -ENOENT;
 564
 565                         error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path);
 566                         if (error)
 567                                 return error;
 568                         dev_path = &tmp_path;
 569                 }
 570         }
 571
 572         buffer = aa_get_buffer(false);
 573         if (!buffer) {
 574                 error = -ENOMEM;
 575                 goto out;
 576         }
 577         if (dev_path) {
 578                 dev_buffer = aa_get_buffer(false);
 579                 if (!dev_buffer) {
 580                         error = -ENOMEM;
 581                         goto out;
 582                 }
 583                 error = fn_for_each_confined(label, profile,
 584                                 match_mnt(subj_cred, profile, path, buffer,
 585                                           dev_path, dev_buffer,
 586                                   type, flags, data, binary));
 587         } else {
 588                 error = fn_for_each_confined(label, profile,
 589                                 match_mnt_path_str(subj_cred, profile, path,
 590                                         buffer, dev_name,
 591                                         type, flags, data, binary, NULL));
 592         }
 593
 594 out:
 595         aa_put_buffer(buffer);
 596         aa_put_buffer(dev_buffer);
 597         if (dev_path)
 598                 path_put(dev_path);
 599
 600         return error;
 601 }
 602
 603 static int profile_umount(const struct cred *subj_cred,
 604                           struct aa_profile *profile, const struct path *path,
 605                           char *buffer)
 606 {
 607         struct aa_ruleset *rules = list_first_entry(&profile->rules,
 608                                                     typeof(*rules), list);
 609         struct aa_perms perms = { };
 610         const char *name = NULL, *info = NULL;
 611         aa_state_t state;
 612         int error;
 613
 614         AA_BUG(!profile);
 615         AA_BUG(!path);
 616
 617         if (!RULE_MEDIATES(rules, AA_CLASS_MOUNT))
 618                 return 0;
 619
 620         error = aa_path_name(path, path_flags(profile, path), buffer, &name,
 621                              &info, profile->disconnected);
 622         if (error)
 623                 goto audit;
 624
 625         state = aa_dfa_match(rules->policy->dfa,
 626                              rules->policy->start[AA_CLASS_MOUNT],
 627                              name);
 628         perms = *aa_lookup_perms(rules->policy, state);
 629         if (AA_MAY_UMOUNT & ~perms.allow)
 630                 error = -EACCES;
 631
 632 audit:
 633         return audit_mount(subj_cred, profile, OP_UMOUNT, name, NULL, NULL,
 634                            NULL, 0, NULL,
 635                            AA_MAY_UMOUNT, &perms, info, error);
 636 }
 637
 638 int aa_umount(const struct cred *subj_cred, struct aa_label *label,
 639               struct vfsmount *mnt, int flags)
 640 {
 641         struct aa_profile *profile;
 642         char *buffer = NULL;
 643         int error;
 644         struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
 645
 646         AA_BUG(!label);
 647         AA_BUG(!mnt);
 648
 649         buffer = aa_get_buffer(false);
 650         if (!buffer)
 651                 return -ENOMEM;
 652
 653         error = fn_for_each_confined(label, profile,
 654                         profile_umount(subj_cred, profile, &path, buffer));
 655         aa_put_buffer(buffer);
 656
 657         return error;
 658 }
 659
 660 /* helper fn for transition on pivotroot
 661  *
 662  * Returns: label for transition or ERR_PTR. Does not return NULL
 663  */
 664 static struct aa_label *build_pivotroot(const struct cred *subj_cred,
 665                                         struct aa_profile *profile,
 666                                         const struct path *new_path,
 667                                         char *new_buffer,
 668                                         const struct path *old_path,
 669                                         char *old_buffer)
 670 {
 671         struct aa_ruleset *rules = list_first_entry(&profile->rules,
 672                                                     typeof(*rules), list);
 673         const char *old_name, *new_name = NULL, *info = NULL;
 674         const char *trans_name = NULL;
 675         struct aa_perms perms = { };
 676         aa_state_t state;
 677         int error;
 678
 679         AA_BUG(!profile);
 680         AA_BUG(!new_path);
 681         AA_BUG(!old_path);
 682
 683         if (profile_unconfined(profile) ||
 684             !RULE_MEDIATES(rules, AA_CLASS_MOUNT))
 685                 return aa_get_newest_label(&profile->label);
 686
 687         error = aa_path_name(old_path, path_flags(profile, old_path),
 688                              old_buffer, &old_name, &info,
 689                              profile->disconnected);
 690         if (error)
 691                 goto audit;
 692         error = aa_path_name(new_path, path_flags(profile, new_path),
 693                              new_buffer, &new_name, &info,
 694                              profile->disconnected);
 695         if (error)
 696                 goto audit;
 697
 698         error = -EACCES;
 699         state = aa_dfa_match(rules->policy->dfa,
 700                              rules->policy->start[AA_CLASS_MOUNT],
 701                              new_name);
 702         state = aa_dfa_null_transition(rules->policy->dfa, state);
 703         state = aa_dfa_match(rules->policy->dfa, state, old_name);
 704         perms = *aa_lookup_perms(rules->policy, state);
 705
 706         if (AA_MAY_PIVOTROOT & perms.allow)
 707                 error = 0;
 708
 709 audit:
 710         error = audit_mount(subj_cred, profile, OP_PIVOTROOT, new_name,
 711                             old_name,
 712                             NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT,
 713                             &perms, info, error);
 714         if (error)
 715                 return ERR_PTR(error);
 716
 717         return aa_get_newest_label(&profile->label);
 718 }
 719
 720 int aa_pivotroot(const struct cred *subj_cred, struct aa_label *label,
 721                  const struct path *old_path,
 722                  const struct path *new_path)
 723 {
 724         struct aa_profile *profile;
 725         struct aa_label *target = NULL;
 726         char *old_buffer = NULL, *new_buffer = NULL, *info = NULL;
 727         int error;
 728
 729         AA_BUG(!label);
 730         AA_BUG(!old_path);
 731         AA_BUG(!new_path);
 732
 733         old_buffer = aa_get_buffer(false);
 734         new_buffer = aa_get_buffer(false);
 735         error = -ENOMEM;
 736         if (!old_buffer || !new_buffer)
 737                 goto out;
 738         target = fn_label_build(label, profile, GFP_KERNEL,
 739                         build_pivotroot(subj_cred, profile, new_path,
 740                                         new_buffer,
 741                                         old_path, old_buffer));
 742         if (!target) {
 743                 info = "label build failed";
 744                 error = -ENOMEM;
 745                 goto fail;
 746         } else if (!IS_ERR(target)) {
 747                 error = aa_replace_current_label(target);
 748                 if (error) {
 749                         /* TODO: audit target */
 750                         aa_put_label(target);
 751                         goto out;
 752                 }
 753                 aa_put_label(target);
 754         } else
 755                 /* already audited error */
 756                 error = PTR_ERR(target);
 757 out:
 758         aa_put_buffer(old_buffer);
 759         aa_put_buffer(new_buffer);
 760
 761         return error;
 762
 763 fail:
 764         /* TODO: add back in auditing of new_name and old_name */
 765         error = fn_for_each(label, profile,
 766                         audit_mount(subj_cred, profile, OP_PIVOTROOT,
 767                                     NULL /*new_name */,
 768                                     NULL /* old_name */,
 769                                     NULL, NULL,
 770                                     0, NULL, AA_MAY_PIVOTROOT, &nullperms, info,
 771                                     error));
 772         goto out;
 773 }