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 static 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->cred_prepared) 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->unsafe |= AA_SECURE_X_NEEDED; 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 * apparmor_bprm_secureexec - determine if secureexec is needed 848 * @bprm: binprm for exec (NOT NULL) 849 * 850 * Returns: %1 if secureexec is needed else %0 851 */ 852 int apparmor_bprm_secureexec(struct linux_binprm *bprm) 853 { 854 /* the decision to use secure exec is computed in set_creds 855 * and stored in bprm->unsafe. 856 */ 857 if (bprm->unsafe & AA_SECURE_X_NEEDED) 858 return 1; 859 860 return 0; 861 } 862 863 /* 864 * Functions for self directed profile change 865 */ 866 867 868 /* helper fn for change_hat 869 * 870 * Returns: label for hat transition OR ERR_PTR. Does NOT return NULL 871 */ 872 static struct aa_label *build_change_hat(struct aa_profile *profile, 873 const char *name, bool sibling) 874 { 875 struct aa_profile *root, *hat = NULL; 876 const char *info = NULL; 877 int error = 0; 878 879 if (sibling && PROFILE_IS_HAT(profile)) { 880 root = aa_get_profile_rcu(&profile->parent); 881 } else if (!sibling && !PROFILE_IS_HAT(profile)) { 882 root = aa_get_profile(profile); 883 } else { 884 info = "conflicting target types"; 885 error = -EPERM; 886 goto audit; 887 } 888 889 hat = aa_find_child(root, name); 890 if (!hat) { 891 error = -ENOENT; 892 if (COMPLAIN_MODE(profile)) { 893 hat = aa_new_null_profile(profile, true, name, 894 GFP_KERNEL); 895 if (!hat) { 896 info = "failed null profile create"; 897 error = -ENOMEM; 898 } 899 } 900 } 901 aa_put_profile(root); 902 903 audit: 904 aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT, 905 name, hat ? hat->base.hname : NULL, 906 hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL, 907 error); 908 if (!hat || (error && error != -ENOENT)) 909 return ERR_PTR(error); 910 /* if hat && error - complain mode, already audited and we adjust for 911 * complain mode allow by returning hat->label 912 */ 913 return &hat->label; 914 } 915 916 /* helper fn for changing into a hat 917 * 918 * Returns: label for hat transition or ERR_PTR. Does not return NULL 919 */ 920 static struct aa_label *change_hat(struct aa_label *label, const char *hats[], 921 int count, int flags) 922 { 923 struct aa_profile *profile, *root, *hat = NULL; 924 struct aa_label *new; 925 struct label_it it; 926 bool sibling = false; 927 const char *name, *info = NULL; 928 int i, error; 929 930 AA_BUG(!label); 931 AA_BUG(!hats); 932 AA_BUG(count < 1); 933 934 if (PROFILE_IS_HAT(labels_profile(label))) 935 sibling = true; 936 937 /*find first matching hat */ 938 for (i = 0; i < count && !hat; i++) { 939 name = hats[i]; 940 label_for_each_in_ns(it, labels_ns(label), label, profile) { 941 if (sibling && PROFILE_IS_HAT(profile)) { 942 root = aa_get_profile_rcu(&profile->parent); 943 } else if (!sibling && !PROFILE_IS_HAT(profile)) { 944 root = aa_get_profile(profile); 945 } else { /* conflicting change type */ 946 info = "conflicting targets types"; 947 error = -EPERM; 948 goto fail; 949 } 950 hat = aa_find_child(root, name); 951 aa_put_profile(root); 952 if (!hat) { 953 if (!COMPLAIN_MODE(profile)) 954 goto outer_continue; 955 /* complain mode succeed as if hat */ 956 } else if (!PROFILE_IS_HAT(hat)) { 957 info = "target not hat"; 958 error = -EPERM; 959 aa_put_profile(hat); 960 goto fail; 961 } 962 aa_put_profile(hat); 963 } 964 /* found a hat for all profiles in ns */ 965 goto build; 966 outer_continue: 967 ; 968 } 969 /* no hats that match, find appropriate error 970 * 971 * In complain mode audit of the failure is based off of the first 972 * hat supplied. This is done due how userspace interacts with 973 * change_hat. 974 */ 975 name = NULL; 976 label_for_each_in_ns(it, labels_ns(label), label, profile) { 977 if (!list_empty(&profile->base.profiles)) { 978 info = "hat not found"; 979 error = -ENOENT; 980 goto fail; 981 } 982 } 983 info = "no hats defined"; 984 error = -ECHILD; 985 986 fail: 987 label_for_each_in_ns(it, labels_ns(label), label, profile) { 988 /* 989 * no target as it has failed to be found or built 990 * 991 * change_hat uses probing and should not log failures 992 * related to missing hats 993 */ 994 /* TODO: get rid of GLOBAL_ROOT_UID */ 995 if (count > 1 || COMPLAIN_MODE(profile)) { 996 aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, 997 AA_MAY_CHANGEHAT, name, NULL, NULL, 998 GLOBAL_ROOT_UID, info, error); 999 } 1000 } 1001 return ERR_PTR(error); 1002 1003 build: 1004 new = fn_label_build_in_ns(label, profile, GFP_KERNEL, 1005 build_change_hat(profile, name, sibling), 1006 aa_get_label(&profile->label)); 1007 if (!new) { 1008 info = "label build failed"; 1009 error = -ENOMEM; 1010 goto fail; 1011 } /* else if (IS_ERR) build_change_hat has logged error so return new */ 1012 1013 return new; 1014 } 1015 1016 /** 1017 * aa_change_hat - change hat to/from subprofile 1018 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0) 1019 * @count: number of hat names in @hats 1020 * @token: magic value to validate the hat change 1021 * @flags: flags affecting behavior of the change 1022 * 1023 * Returns %0 on success, error otherwise. 1024 * 1025 * Change to the first profile specified in @hats that exists, and store 1026 * the @hat_magic in the current task context. If the count == 0 and the 1027 * @token matches that stored in the current task context, return to the 1028 * top level profile. 1029 * 1030 * change_hat only applies to profiles in the current ns, and each profile 1031 * in the ns must make the same transition otherwise change_hat will fail. 1032 */ 1033 int aa_change_hat(const char *hats[], int count, u64 token, int flags) 1034 { 1035 const struct cred *cred; 1036 struct aa_task_ctx *ctx; 1037 struct aa_label *label, *previous, *new = NULL, *target = NULL; 1038 struct aa_profile *profile; 1039 struct aa_perms perms = {}; 1040 const char *info = NULL; 1041 int error = 0; 1042 1043 /* 1044 * Fail explicitly requested domain transitions if no_new_privs. 1045 * There is no exception for unconfined as change_hat is not 1046 * available. 1047 */ 1048 if (task_no_new_privs(current)) { 1049 /* not an apparmor denial per se, so don't log it */ 1050 AA_DEBUG("no_new_privs - change_hat denied"); 1051 return -EPERM; 1052 } 1053 1054 /* released below */ 1055 cred = get_current_cred(); 1056 ctx = cred_ctx(cred); 1057 label = aa_get_newest_cred_label(cred); 1058 previous = aa_get_newest_label(ctx->previous); 1059 1060 if (unconfined(label)) { 1061 info = "unconfined can not change_hat"; 1062 error = -EPERM; 1063 goto fail; 1064 } 1065 1066 if (count) { 1067 new = change_hat(label, hats, count, flags); 1068 AA_BUG(!new); 1069 if (IS_ERR(new)) { 1070 error = PTR_ERR(new); 1071 new = NULL; 1072 /* already audited */ 1073 goto out; 1074 } 1075 1076 error = may_change_ptraced_domain(new, &info); 1077 if (error) 1078 goto fail; 1079 1080 if (flags & AA_CHANGE_TEST) 1081 goto out; 1082 1083 target = new; 1084 error = aa_set_current_hat(new, token); 1085 if (error == -EACCES) 1086 /* kill task in case of brute force attacks */ 1087 goto kill; 1088 } else if (previous && !(flags & AA_CHANGE_TEST)) { 1089 /* Return to saved label. Kill task if restore fails 1090 * to avoid brute force attacks 1091 */ 1092 target = previous; 1093 error = aa_restore_previous_label(token); 1094 if (error) { 1095 if (error == -EACCES) 1096 goto kill; 1097 goto fail; 1098 } 1099 } /* else ignore @flags && restores when there is no saved profile */ 1100 1101 out: 1102 aa_put_label(new); 1103 aa_put_label(previous); 1104 aa_put_label(label); 1105 put_cred(cred); 1106 1107 return error; 1108 1109 kill: 1110 info = "failed token match"; 1111 perms.kill = AA_MAY_CHANGEHAT; 1112 1113 fail: 1114 fn_for_each_in_ns(label, profile, 1115 aa_audit_file(profile, &perms, OP_CHANGE_HAT, 1116 AA_MAY_CHANGEHAT, NULL, NULL, target, 1117 GLOBAL_ROOT_UID, info, error)); 1118 1119 goto out; 1120 } 1121 1122 1123 static int change_profile_perms_wrapper(const char *op, const char *name, 1124 struct aa_profile *profile, 1125 struct aa_label *target, bool stack, 1126 u32 request, struct aa_perms *perms) 1127 { 1128 const char *info = NULL; 1129 int error = 0; 1130 1131 /* 1132 * Fail explicitly requested domain transitions when no_new_privs 1133 * and not unconfined OR the transition results in a stack on 1134 * the current label. 1135 * Stacking domain transitions and transitions from unconfined are 1136 * allowed even when no_new_privs is set because this aways results 1137 * in a reduction of permissions. 1138 */ 1139 if (task_no_new_privs(current) && !stack && 1140 !profile_unconfined(profile) && 1141 !aa_label_is_subset(target, &profile->label)) { 1142 info = "no new privs"; 1143 error = -EPERM; 1144 } 1145 1146 if (!error) 1147 error = change_profile_perms(profile, target, stack, request, 1148 profile->file.start, perms); 1149 if (error) 1150 error = aa_audit_file(profile, perms, op, request, name, 1151 NULL, target, GLOBAL_ROOT_UID, info, 1152 error); 1153 1154 return error; 1155 } 1156 1157 /** 1158 * aa_change_profile - perform a one-way profile transition 1159 * @fqname: name of profile may include namespace (NOT NULL) 1160 * @onexec: whether this transition is to take place immediately or at exec 1161 * @flags: flags affecting change behavior 1162 * 1163 * Change to new profile @name. Unlike with hats, there is no way 1164 * to change back. If @name isn't specified the current profile name is 1165 * used. 1166 * If @onexec then the transition is delayed until 1167 * the next exec. 1168 * 1169 * Returns %0 on success, error otherwise. 1170 */ 1171 int aa_change_profile(const char *fqname, int flags) 1172 { 1173 struct aa_label *label, *new = NULL, *target = NULL; 1174 struct aa_profile *profile; 1175 struct aa_perms perms = {}; 1176 const char *info = NULL; 1177 const char *auditname = fqname; /* retain leading & if stack */ 1178 bool stack = flags & AA_CHANGE_STACK; 1179 int error = 0; 1180 char *op; 1181 u32 request; 1182 1183 if (!fqname || !*fqname) { 1184 AA_DEBUG("no profile name"); 1185 return -EINVAL; 1186 } 1187 1188 if (flags & AA_CHANGE_ONEXEC) { 1189 request = AA_MAY_ONEXEC; 1190 if (stack) 1191 op = OP_STACK_ONEXEC; 1192 else 1193 op = OP_CHANGE_ONEXEC; 1194 } else { 1195 request = AA_MAY_CHANGE_PROFILE; 1196 if (stack) 1197 op = OP_STACK; 1198 else 1199 op = OP_CHANGE_PROFILE; 1200 } 1201 1202 label = aa_get_current_label(); 1203 1204 if (*fqname == '&') { 1205 stack = true; 1206 /* don't have label_parse() do stacking */ 1207 fqname++; 1208 } 1209 target = aa_label_parse(label, fqname, GFP_KERNEL, true, false); 1210 if (IS_ERR(target)) { 1211 struct aa_profile *tprofile; 1212 1213 info = "label not found"; 1214 error = PTR_ERR(target); 1215 target = NULL; 1216 /* 1217 * TODO: fixme using labels_profile is not right - do profile 1218 * per complain profile 1219 */ 1220 if ((flags & AA_CHANGE_TEST) || 1221 !COMPLAIN_MODE(labels_profile(label))) 1222 goto audit; 1223 /* released below */ 1224 tprofile = aa_new_null_profile(labels_profile(label), false, 1225 fqname, GFP_KERNEL); 1226 if (!tprofile) { 1227 info = "failed null profile create"; 1228 error = -ENOMEM; 1229 goto audit; 1230 } 1231 target = &tprofile->label; 1232 goto check; 1233 } 1234 1235 /* 1236 * self directed transitions only apply to current policy ns 1237 * TODO: currently requiring perms for stacking and straight change 1238 * stacking doesn't strictly need this. Determine how much 1239 * we want to loosen this restriction for stacking 1240 * 1241 * if (!stack) { 1242 */ 1243 error = fn_for_each_in_ns(label, profile, 1244 change_profile_perms_wrapper(op, auditname, 1245 profile, target, stack, 1246 request, &perms)); 1247 if (error) 1248 /* auditing done in change_profile_perms_wrapper */ 1249 goto out; 1250 1251 /* } */ 1252 1253 check: 1254 /* check if tracing task is allowed to trace target domain */ 1255 error = may_change_ptraced_domain(target, &info); 1256 if (error && !fn_for_each_in_ns(label, profile, 1257 COMPLAIN_MODE(profile))) 1258 goto audit; 1259 1260 /* TODO: add permission check to allow this 1261 * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) { 1262 * info = "not a single threaded task"; 1263 * error = -EACCES; 1264 * goto audit; 1265 * } 1266 */ 1267 if (flags & AA_CHANGE_TEST) 1268 goto out; 1269 1270 if (!(flags & AA_CHANGE_ONEXEC)) { 1271 /* only transition profiles in the current ns */ 1272 if (stack) 1273 new = aa_label_merge(label, target, GFP_KERNEL); 1274 else 1275 new = fn_label_build_in_ns(label, profile, GFP_KERNEL, 1276 aa_get_label(target), 1277 aa_get_label(&profile->label)); 1278 if (IS_ERR_OR_NULL(new)) { 1279 info = "failed to build target label"; 1280 error = PTR_ERR(new); 1281 new = NULL; 1282 perms.allow = 0; 1283 goto audit; 1284 } 1285 error = aa_replace_current_label(new); 1286 } else 1287 /* full transition will be built in exec path */ 1288 error = aa_set_current_onexec(target, stack); 1289 1290 audit: 1291 error = fn_for_each_in_ns(label, profile, 1292 aa_audit_file(profile, &perms, op, request, auditname, 1293 NULL, new ? new : target, 1294 GLOBAL_ROOT_UID, info, error)); 1295 1296 out: 1297 aa_put_label(new); 1298 aa_put_label(target); 1299 aa_put_label(label); 1300 1301 return error; 1302 } 1303