linux/security/apparmor/policy.c
<<
>>
Prefs
   1/*
   2 * AppArmor security module
   3 *
   4 * This file contains AppArmor policy manipulation functions
   5 *
   6 * Copyright (C) 1998-2008 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 * AppArmor policy is based around profiles, which contain the rules a
  16 * task is confined by.  Every task in the system has a profile attached
  17 * to it determined either by matching "unconfined" tasks against the
  18 * visible set of profiles or by following a profiles attachment rules.
  19 *
  20 * Each profile exists in a profile namespace which is a container of
  21 * visible profiles.  Each namespace contains a special "unconfined" profile,
  22 * which doesn't enforce any confinement on a task beyond DAC.
  23 *
  24 * Namespace and profile names can be written together in either
  25 * of two syntaxes.
  26 *      :namespace:profile - used by kernel interfaces for easy detection
  27 *      namespace://profile - used by policy
  28 *
  29 * Profile names can not start with : or @ or ^ and may not contain \0
  30 *
  31 * Reserved profile names
  32 *      unconfined - special automatically generated unconfined profile
  33 *      inherit - special name to indicate profile inheritance
  34 *      null-XXXX-YYYY - special automatically generated learning profiles
  35 *
  36 * Namespace names may not start with / or @ and may not contain \0 or :
  37 * Reserved namespace names
  38 *      user-XXXX - user defined profiles
  39 *
  40 * a // in a profile or namespace name indicates a hierarchical name with the
  41 * name before the // being the parent and the name after the child.
  42 *
  43 * Profile and namespace hierarchies serve two different but similar purposes.
  44 * The namespace contains the set of visible profiles that are considered
  45 * for attachment.  The hierarchy of namespaces allows for virtualizing
  46 * the namespace so that for example a chroot can have its own set of profiles
  47 * which may define some local user namespaces.
  48 * The profile hierarchy severs two distinct purposes,
  49 * -  it allows for sub profiles or hats, which allows an application to run
  50 *    subprograms under its own profile with different restriction than it
  51 *    self, and not have it use the system profile.
  52 *    eg. if a mail program starts an editor, the policy might make the
  53 *        restrictions tighter on the editor tighter than the mail program,
  54 *        and definitely different than general editor restrictions
  55 * - it allows for binary hierarchy of profiles, so that execution history
  56 *   is preserved.  This feature isn't exploited by AppArmor reference policy
  57 *   but is allowed.  NOTE: this is currently suboptimal because profile
  58 *   aliasing is not currently implemented so that a profile for each
  59 *   level must be defined.
  60 *   eg. /bin/bash///bin/ls as a name would indicate /bin/ls was started
  61 *       from /bin/bash
  62 *
  63 *   A profile or namespace name that can contain one or more // separators
  64 *   is referred to as an hname (hierarchical).
  65 *   eg.  /bin/bash//bin/ls
  66 *
  67 *   An fqname is a name that may contain both namespace and profile hnames.
  68 *   eg. :ns:/bin/bash//bin/ls
  69 *
  70 * NOTES:
  71 *   - locking of profile lists is currently fairly coarse.  All profile
  72 *     lists within a namespace use the namespace lock.
  73 * FIXME: move profile lists to using rcu_lists
  74 */
  75
  76#include <linux/slab.h>
  77#include <linux/spinlock.h>
  78#include <linux/string.h>
  79
  80#include "include/apparmor.h"
  81#include "include/capability.h"
  82#include "include/context.h"
  83#include "include/file.h"
  84#include "include/ipc.h"
  85#include "include/match.h"
  86#include "include/path.h"
  87#include "include/policy.h"
  88#include "include/policy_unpack.h"
  89#include "include/resource.h"
  90#include "include/sid.h"
  91
  92
  93/* root profile namespace */
  94struct aa_namespace *root_ns;
  95
  96const char *const profile_mode_names[] = {
  97        "enforce",
  98        "complain",
  99        "kill",
 100};
 101
 102/**
 103 * hname_tail - find the last component of an hname
 104 * @name: hname to find the base profile name component of  (NOT NULL)
 105 *
 106 * Returns: the tail (base profile name) name component of an hname
 107 */
 108static const char *hname_tail(const char *hname)
 109{
 110        char *split;
 111        hname = strim((char *)hname);
 112        for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
 113                hname = split + 2;
 114
 115        return hname;
 116}
 117
 118/**
 119 * policy_init - initialize a policy structure
 120 * @policy: policy to initialize  (NOT NULL)
 121 * @prefix: prefix name if any is required.  (MAYBE NULL)
 122 * @name: name of the policy, init will make a copy of it  (NOT NULL)
 123 *
 124 * Note: this fn creates a copy of strings passed in
 125 *
 126 * Returns: true if policy init successful
 127 */
 128static bool policy_init(struct aa_policy *policy, const char *prefix,
 129                        const char *name)
 130{
 131        /* freed by policy_free */
 132        if (prefix) {
 133                policy->hname = kmalloc(strlen(prefix) + strlen(name) + 3,
 134                                        GFP_KERNEL);
 135                if (policy->hname)
 136                        sprintf(policy->hname, "%s//%s", prefix, name);
 137        } else
 138                policy->hname = kstrdup(name, GFP_KERNEL);
 139        if (!policy->hname)
 140                return 0;
 141        /* base.name is a substring of fqname */
 142        policy->name = (char *)hname_tail(policy->hname);
 143        INIT_LIST_HEAD(&policy->list);
 144        INIT_LIST_HEAD(&policy->profiles);
 145        kref_init(&policy->count);
 146
 147        return 1;
 148}
 149
 150/**
 151 * policy_destroy - free the elements referenced by @policy
 152 * @policy: policy that is to have its elements freed  (NOT NULL)
 153 */
 154static void policy_destroy(struct aa_policy *policy)
 155{
 156        /* still contains profiles -- invalid */
 157        if (!list_empty(&policy->profiles)) {
 158                AA_ERROR("%s: internal error, "
 159                         "policy '%s' still contains profiles\n",
 160                         __func__, policy->name);
 161                BUG();
 162        }
 163        if (!list_empty(&policy->list)) {
 164                AA_ERROR("%s: internal error, policy '%s' still on list\n",
 165                         __func__, policy->name);
 166                BUG();
 167        }
 168
 169        /* don't free name as its a subset of hname */
 170        kzfree(policy->hname);
 171}
 172
 173/**
 174 * __policy_find - find a policy by @name on a policy list
 175 * @head: list to search  (NOT NULL)
 176 * @name: name to search for  (NOT NULL)
 177 *
 178 * Requires: correct locks for the @head list be held
 179 *
 180 * Returns: unrefcounted policy that match @name or NULL if not found
 181 */
 182static struct aa_policy *__policy_find(struct list_head *head, const char *name)
 183{
 184        struct aa_policy *policy;
 185
 186        list_for_each_entry(policy, head, list) {
 187                if (!strcmp(policy->name, name))
 188                        return policy;
 189        }
 190        return NULL;
 191}
 192
 193/**
 194 * __policy_strn_find - find a policy that's name matches @len chars of @str
 195 * @head: list to search  (NOT NULL)
 196 * @str: string to search for  (NOT NULL)
 197 * @len: length of match required
 198 *
 199 * Requires: correct locks for the @head list be held
 200 *
 201 * Returns: unrefcounted policy that match @str or NULL if not found
 202 *
 203 * if @len == strlen(@strlen) then this is equiv to __policy_find
 204 * other wise it allows searching for policy by a partial match of name
 205 */
 206static struct aa_policy *__policy_strn_find(struct list_head *head,
 207                                            const char *str, int len)
 208{
 209        struct aa_policy *policy;
 210
 211        list_for_each_entry(policy, head, list) {
 212                if (aa_strneq(policy->name, str, len))
 213                        return policy;
 214        }
 215
 216        return NULL;
 217}
 218
 219/*
 220 * Routines for AppArmor namespaces
 221 */
 222
 223static const char *hidden_ns_name = "---";
 224/**
 225 * aa_ns_visible - test if @view is visible from @curr
 226 * @curr: namespace to treat as the parent (NOT NULL)
 227 * @view:  namespace to test if visible from @curr (NOT NULL)
 228 *
 229 * Returns: true if @view is visible from @curr else false
 230 */
 231bool aa_ns_visible(struct aa_namespace *curr, struct aa_namespace *view)
 232{
 233        if (curr == view)
 234                return true;
 235
 236        for ( ; view; view = view->parent) {
 237                if (view->parent == curr)
 238                        return true;
 239        }
 240        return false;
 241}
 242
 243/**
 244 * aa_na_name - Find the ns name to display for @view from @curr
 245 * @curr - current namespace (NOT NULL)
 246 * @view - namespace attempting to view (NOT NULL)
 247 *
 248 * Returns: name of @view visible from @curr
 249 */
 250const char *aa_ns_name(struct aa_namespace *curr, struct aa_namespace *view)
 251{
 252        /* if view == curr then the namespace name isn't displayed */
 253        if (curr == view)
 254                return "";
 255
 256        if (aa_ns_visible(curr, view)) {
 257                /* at this point if a ns is visible it is in a view ns
 258                 * thus the curr ns.hname is a prefix of its name.
 259                 * Only output the virtualized portion of the name
 260                 * Add + 2 to skip over // separating curr hname prefix
 261                 * from the visible tail of the views hname
 262                 */
 263                return view->base.hname + strlen(curr->base.hname) + 2;
 264        } else
 265                return hidden_ns_name;
 266}
 267
 268/**
 269 * alloc_namespace - allocate, initialize and return a new namespace
 270 * @prefix: parent namespace name (MAYBE NULL)
 271 * @name: a preallocated name  (NOT NULL)
 272 *
 273 * Returns: refcounted namespace or NULL on failure.
 274 */
 275static struct aa_namespace *alloc_namespace(const char *prefix,
 276                                            const char *name)
 277{
 278        struct aa_namespace *ns;
 279
 280        ns = kzalloc(sizeof(*ns), GFP_KERNEL);
 281        AA_DEBUG("%s(%p)\n", __func__, ns);
 282        if (!ns)
 283                return NULL;
 284        if (!policy_init(&ns->base, prefix, name))
 285                goto fail_ns;
 286
 287        INIT_LIST_HEAD(&ns->sub_ns);
 288        rwlock_init(&ns->lock);
 289
 290        /* released by free_namespace */
 291        ns->unconfined = aa_alloc_profile("unconfined");
 292        if (!ns->unconfined)
 293                goto fail_unconfined;
 294
 295        ns->unconfined->sid = aa_alloc_sid();
 296        ns->unconfined->flags = PFLAG_UNCONFINED | PFLAG_IX_ON_NAME_ERROR |
 297            PFLAG_IMMUTABLE;
 298
 299        /*
 300         * released by free_namespace, however __remove_namespace breaks
 301         * the cyclic references (ns->unconfined, and unconfined->ns) and
 302         * replaces with refs to parent namespace unconfined
 303         */
 304        ns->unconfined->ns = aa_get_namespace(ns);
 305
 306        return ns;
 307
 308fail_unconfined:
 309        kzfree(ns->base.hname);
 310fail_ns:
 311        kzfree(ns);
 312        return NULL;
 313}
 314
 315/**
 316 * free_namespace - free a profile namespace
 317 * @ns: the namespace to free  (MAYBE NULL)
 318 *
 319 * Requires: All references to the namespace must have been put, if the
 320 *           namespace was referenced by a profile confining a task,
 321 */
 322static void free_namespace(struct aa_namespace *ns)
 323{
 324        if (!ns)
 325                return;
 326
 327        policy_destroy(&ns->base);
 328        aa_put_namespace(ns->parent);
 329
 330        if (ns->unconfined && ns->unconfined->ns == ns)
 331                ns->unconfined->ns = NULL;
 332
 333        aa_put_profile(ns->unconfined);
 334        kzfree(ns);
 335}
 336
 337/**
 338 * aa_free_namespace_kref - free aa_namespace by kref (see aa_put_namespace)
 339 * @kr: kref callback for freeing of a namespace  (NOT NULL)
 340 */
 341void aa_free_namespace_kref(struct kref *kref)
 342{
 343        free_namespace(container_of(kref, struct aa_namespace, base.count));
 344}
 345
 346/**
 347 * __aa_find_namespace - find a namespace on a list by @name
 348 * @head: list to search for namespace on  (NOT NULL)
 349 * @name: name of namespace to look for  (NOT NULL)
 350 *
 351 * Returns: unrefcounted namespace
 352 *
 353 * Requires: ns lock be held
 354 */
 355static struct aa_namespace *__aa_find_namespace(struct list_head *head,
 356                                                const char *name)
 357{
 358        return (struct aa_namespace *)__policy_find(head, name);
 359}
 360
 361/**
 362 * aa_find_namespace  -  look up a profile namespace on the namespace list
 363 * @root: namespace to search in  (NOT NULL)
 364 * @name: name of namespace to find  (NOT NULL)
 365 *
 366 * Returns: a refcounted namespace on the list, or NULL if no namespace
 367 *          called @name exists.
 368 *
 369 * refcount released by caller
 370 */
 371struct aa_namespace *aa_find_namespace(struct aa_namespace *root,
 372                                       const char *name)
 373{
 374        struct aa_namespace *ns = NULL;
 375
 376        read_lock(&root->lock);
 377        ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));
 378        read_unlock(&root->lock);
 379
 380        return ns;
 381}
 382
 383/**
 384 * aa_prepare_namespace - find an existing or create a new namespace of @name
 385 * @name: the namespace to find or add  (MAYBE NULL)
 386 *
 387 * Returns: refcounted namespace or NULL if failed to create one
 388 */
 389static struct aa_namespace *aa_prepare_namespace(const char *name)
 390{
 391        struct aa_namespace *ns, *root;
 392
 393        root = aa_current_profile()->ns;
 394
 395        write_lock(&root->lock);
 396
 397        /* if name isn't specified the profile is loaded to the current ns */
 398        if (!name) {
 399                /* released by caller */
 400                ns = aa_get_namespace(root);
 401                goto out;
 402        }
 403
 404        /* try and find the specified ns and if it doesn't exist create it */
 405        /* released by caller */
 406        ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));
 407        if (!ns) {
 408                /* namespace not found */
 409                struct aa_namespace *new_ns;
 410                write_unlock(&root->lock);
 411                new_ns = alloc_namespace(root->base.hname, name);
 412                if (!new_ns)
 413                        return NULL;
 414                write_lock(&root->lock);
 415                /* test for race when new_ns was allocated */
 416                ns = __aa_find_namespace(&root->sub_ns, name);
 417                if (!ns) {
 418                        /* add parent ref */
 419                        new_ns->parent = aa_get_namespace(root);
 420
 421                        list_add(&new_ns->base.list, &root->sub_ns);
 422                        /* add list ref */
 423                        ns = aa_get_namespace(new_ns);
 424                } else {
 425                        /* raced so free the new one */
 426                        free_namespace(new_ns);
 427                        /* get reference on namespace */
 428                        aa_get_namespace(ns);
 429                }
 430        }
 431out:
 432        write_unlock(&root->lock);
 433
 434        /* return ref */
 435        return ns;
 436}
 437
 438/**
 439 * __list_add_profile - add a profile to a list
 440 * @list: list to add it to  (NOT NULL)
 441 * @profile: the profile to add  (NOT NULL)
 442 *
 443 * refcount @profile, should be put by __list_remove_profile
 444 *
 445 * Requires: namespace lock be held, or list not be shared
 446 */
 447static void __list_add_profile(struct list_head *list,
 448                               struct aa_profile *profile)
 449{
 450        list_add(&profile->base.list, list);
 451        /* get list reference */
 452        aa_get_profile(profile);
 453}
 454
 455/**
 456 * __list_remove_profile - remove a profile from the list it is on
 457 * @profile: the profile to remove  (NOT NULL)
 458 *
 459 * remove a profile from the list, warning generally removal should
 460 * be done with __replace_profile as most profile removals are
 461 * replacements to the unconfined profile.
 462 *
 463 * put @profile list refcount
 464 *
 465 * Requires: namespace lock be held, or list not have been live
 466 */
 467static void __list_remove_profile(struct aa_profile *profile)
 468{
 469        list_del_init(&profile->base.list);
 470        if (!(profile->flags & PFLAG_NO_LIST_REF))
 471                /* release list reference */
 472                aa_put_profile(profile);
 473}
 474
 475/**
 476 * __replace_profile - replace @old with @new on a list
 477 * @old: profile to be replaced  (NOT NULL)
 478 * @new: profile to replace @old with  (NOT NULL)
 479 *
 480 * Will duplicate and refcount elements that @new inherits from @old
 481 * and will inherit @old children.
 482 *
 483 * refcount @new for list, put @old list refcount
 484 *
 485 * Requires: namespace list lock be held, or list not be shared
 486 */
 487static void __replace_profile(struct aa_profile *old, struct aa_profile *new)
 488{
 489        struct aa_policy *policy;
 490        struct aa_profile *child, *tmp;
 491
 492        if (old->parent)
 493                policy = &old->parent->base;
 494        else
 495                policy = &old->ns->base;
 496
 497        /* released when @new is freed */
 498        new->parent = aa_get_profile(old->parent);
 499        new->ns = aa_get_namespace(old->ns);
 500        new->sid = old->sid;
 501        __list_add_profile(&policy->profiles, new);
 502        /* inherit children */
 503        list_for_each_entry_safe(child, tmp, &old->base.profiles, base.list) {
 504                aa_put_profile(child->parent);
 505                child->parent = aa_get_profile(new);
 506                /* list refcount transferred to @new*/
 507                list_move(&child->base.list, &new->base.profiles);
 508        }
 509
 510        /* released by free_profile */
 511        old->replacedby = aa_get_profile(new);
 512        __list_remove_profile(old);
 513}
 514
 515static void __profile_list_release(struct list_head *head);
 516
 517/**
 518 * __remove_profile - remove old profile, and children
 519 * @profile: profile to be replaced  (NOT NULL)
 520 *
 521 * Requires: namespace list lock be held, or list not be shared
 522 */
 523static void __remove_profile(struct aa_profile *profile)
 524{
 525        /* release any children lists first */
 526        __profile_list_release(&profile->base.profiles);
 527        /* released by free_profile */
 528        profile->replacedby = aa_get_profile(profile->ns->unconfined);
 529        __list_remove_profile(profile);
 530}
 531
 532/**
 533 * __profile_list_release - remove all profiles on the list and put refs
 534 * @head: list of profiles  (NOT NULL)
 535 *
 536 * Requires: namespace lock be held
 537 */
 538static void __profile_list_release(struct list_head *head)
 539{
 540        struct aa_profile *profile, *tmp;
 541        list_for_each_entry_safe(profile, tmp, head, base.list)
 542                __remove_profile(profile);
 543}
 544
 545static void __ns_list_release(struct list_head *head);
 546
 547/**
 548 * destroy_namespace - remove everything contained by @ns
 549 * @ns: namespace to have it contents removed  (NOT NULL)
 550 */
 551static void destroy_namespace(struct aa_namespace *ns)
 552{
 553        if (!ns)
 554                return;
 555
 556        write_lock(&ns->lock);
 557        /* release all profiles in this namespace */
 558        __profile_list_release(&ns->base.profiles);
 559
 560        /* release all sub namespaces */
 561        __ns_list_release(&ns->sub_ns);
 562
 563        write_unlock(&ns->lock);
 564}
 565
 566/**
 567 * __remove_namespace - remove a namespace and all its children
 568 * @ns: namespace to be removed  (NOT NULL)
 569 *
 570 * Requires: ns->parent->lock be held and ns removed from parent.
 571 */
 572static void __remove_namespace(struct aa_namespace *ns)
 573{
 574        struct aa_profile *unconfined = ns->unconfined;
 575
 576        /* remove ns from namespace list */
 577        list_del_init(&ns->base.list);
 578
 579        /*
 580         * break the ns, unconfined profile cyclic reference and forward
 581         * all new unconfined profiles requests to the parent namespace
 582         * This will result in all confined tasks that have a profile
 583         * being removed, inheriting the parent->unconfined profile.
 584         */
 585        if (ns->parent)
 586                ns->unconfined = aa_get_profile(ns->parent->unconfined);
 587
 588        destroy_namespace(ns);
 589
 590        /* release original ns->unconfined ref */
 591        aa_put_profile(unconfined);
 592        /* release ns->base.list ref, from removal above */
 593        aa_put_namespace(ns);
 594}
 595
 596/**
 597 * __ns_list_release - remove all profile namespaces on the list put refs
 598 * @head: list of profile namespaces  (NOT NULL)
 599 *
 600 * Requires: namespace lock be held
 601 */
 602static void __ns_list_release(struct list_head *head)
 603{
 604        struct aa_namespace *ns, *tmp;
 605        list_for_each_entry_safe(ns, tmp, head, base.list)
 606                __remove_namespace(ns);
 607
 608}
 609
 610/**
 611 * aa_alloc_root_ns - allocate the root profile namespace
 612 *
 613 * Returns: %0 on success else error
 614 *
 615 */
 616int __init aa_alloc_root_ns(void)
 617{
 618        /* released by aa_free_root_ns - used as list ref*/
 619        root_ns = alloc_namespace(NULL, "root");
 620        if (!root_ns)
 621                return -ENOMEM;
 622
 623        return 0;
 624}
 625
 626 /**
 627  * aa_free_root_ns - free the root profile namespace
 628  */
 629void __init aa_free_root_ns(void)
 630 {
 631         struct aa_namespace *ns = root_ns;
 632         root_ns = NULL;
 633
 634         destroy_namespace(ns);
 635         aa_put_namespace(ns);
 636}
 637
 638/**
 639 * aa_alloc_profile - allocate, initialize and return a new profile
 640 * @hname: name of the profile  (NOT NULL)
 641 *
 642 * Returns: refcount profile or NULL on failure
 643 */
 644struct aa_profile *aa_alloc_profile(const char *hname)
 645{
 646        struct aa_profile *profile;
 647
 648        /* freed by free_profile - usually through aa_put_profile */
 649        profile = kzalloc(sizeof(*profile), GFP_KERNEL);
 650        if (!profile)
 651                return NULL;
 652
 653        if (!policy_init(&profile->base, NULL, hname)) {
 654                kzfree(profile);
 655                return NULL;
 656        }
 657
 658        /* refcount released by caller */
 659        return profile;
 660}
 661
 662/**
 663 * aa_new_null_profile - create a new null-X learning profile
 664 * @parent: profile that caused this profile to be created (NOT NULL)
 665 * @hat: true if the null- learning profile is a hat
 666 *
 667 * Create a null- complain mode profile used in learning mode.  The name of
 668 * the profile is unique and follows the format of parent//null-sid.
 669 *
 670 * null profiles are added to the profile list but the list does not
 671 * hold a count on them so that they are automatically released when
 672 * not in use.
 673 *
 674 * Returns: new refcounted profile else NULL on failure
 675 */
 676struct aa_profile *aa_new_null_profile(struct aa_profile *parent, int hat)
 677{
 678        struct aa_profile *profile = NULL;
 679        char *name;
 680        u32 sid = aa_alloc_sid();
 681
 682        /* freed below */
 683        name = kmalloc(strlen(parent->base.hname) + 2 + 7 + 8, GFP_KERNEL);
 684        if (!name)
 685                goto fail;
 686        sprintf(name, "%s//null-%x", parent->base.hname, sid);
 687
 688        profile = aa_alloc_profile(name);
 689        kfree(name);
 690        if (!profile)
 691                goto fail;
 692
 693        profile->sid = sid;
 694        profile->mode = APPARMOR_COMPLAIN;
 695        profile->flags = PFLAG_NULL;
 696        if (hat)
 697                profile->flags |= PFLAG_HAT;
 698
 699        /* released on free_profile */
 700        profile->parent = aa_get_profile(parent);
 701        profile->ns = aa_get_namespace(parent->ns);
 702
 703        write_lock(&profile->ns->lock);
 704        __list_add_profile(&parent->base.profiles, profile);
 705        write_unlock(&profile->ns->lock);
 706
 707        /* refcount released by caller */
 708        return profile;
 709
 710fail:
 711        aa_free_sid(sid);
 712        return NULL;
 713}
 714
 715/**
 716 * free_profile - free a profile
 717 * @profile: the profile to free  (MAYBE NULL)
 718 *
 719 * Free a profile, its hats and null_profile. All references to the profile,
 720 * its hats and null_profile must have been put.
 721 *
 722 * If the profile was referenced from a task context, free_profile() will
 723 * be called from an rcu callback routine, so we must not sleep here.
 724 */
 725static void free_profile(struct aa_profile *profile)
 726{
 727        struct aa_profile *p;
 728
 729        AA_DEBUG("%s(%p)\n", __func__, profile);
 730
 731        if (!profile)
 732                return;
 733
 734        if (!list_empty(&profile->base.list)) {
 735                AA_ERROR("%s: internal error, "
 736                         "profile '%s' still on ns list\n",
 737                         __func__, profile->base.name);
 738                BUG();
 739        }
 740
 741        /* free children profiles */
 742        policy_destroy(&profile->base);
 743        aa_put_profile(profile->parent);
 744
 745        aa_put_namespace(profile->ns);
 746        kzfree(profile->rename);
 747
 748        aa_free_file_rules(&profile->file);
 749        aa_free_cap_rules(&profile->caps);
 750        aa_free_rlimit_rules(&profile->rlimits);
 751
 752        aa_free_sid(profile->sid);
 753        aa_put_dfa(profile->xmatch);
 754        aa_put_dfa(profile->policy.dfa);
 755
 756        /* put the profile reference for replacedby, but not via
 757         * put_profile(kref_put).
 758         * replacedby can form a long chain that can result in cascading
 759         * frees that blows the stack because kref_put makes a nested fn
 760         * call (it looks like recursion, with free_profile calling
 761         * free_profile) for each profile in the chain lp#1056078.
 762         */
 763        for (p = profile->replacedby; p; ) {
 764                if (atomic_dec_and_test(&p->base.count.refcount)) {
 765                        /* no more refs on p, grab its replacedby */
 766                        struct aa_profile *next = p->replacedby;
 767                        /* break the chain */
 768                        p->replacedby = NULL;
 769                        /* now free p, chain is broken */
 770                        free_profile(p);
 771
 772                        /* follow up with next profile in the chain */
 773                        p = next;
 774                } else
 775                        break;
 776        }
 777
 778        kzfree(profile);
 779}
 780
 781/**
 782 * aa_free_profile_kref - free aa_profile by kref (called by aa_put_profile)
 783 * @kr: kref callback for freeing of a profile  (NOT NULL)
 784 */
 785void aa_free_profile_kref(struct kref *kref)
 786{
 787        struct aa_profile *p = container_of(kref, struct aa_profile,
 788                                            base.count);
 789
 790        free_profile(p);
 791}
 792
 793/* TODO: profile accounting - setup in remove */
 794
 795/**
 796 * __find_child - find a profile on @head list with a name matching @name
 797 * @head: list to search  (NOT NULL)
 798 * @name: name of profile (NOT NULL)
 799 *
 800 * Requires: ns lock protecting list be held
 801 *
 802 * Returns: unrefcounted profile ptr, or NULL if not found
 803 */
 804static struct aa_profile *__find_child(struct list_head *head, const char *name)
 805{
 806        return (struct aa_profile *)__policy_find(head, name);
 807}
 808
 809/**
 810 * __strn_find_child - find a profile on @head list using substring of @name
 811 * @head: list to search  (NOT NULL)
 812 * @name: name of profile (NOT NULL)
 813 * @len: length of @name substring to match
 814 *
 815 * Requires: ns lock protecting list be held
 816 *
 817 * Returns: unrefcounted profile ptr, or NULL if not found
 818 */
 819static struct aa_profile *__strn_find_child(struct list_head *head,
 820                                            const char *name, int len)
 821{
 822        return (struct aa_profile *)__policy_strn_find(head, name, len);
 823}
 824
 825/**
 826 * aa_find_child - find a profile by @name in @parent
 827 * @parent: profile to search  (NOT NULL)
 828 * @name: profile name to search for  (NOT NULL)
 829 *
 830 * Returns: a refcounted profile or NULL if not found
 831 */
 832struct aa_profile *aa_find_child(struct aa_profile *parent, const char *name)
 833{
 834        struct aa_profile *profile;
 835
 836        read_lock(&parent->ns->lock);
 837        profile = aa_get_profile(__find_child(&parent->base.profiles, name));
 838        read_unlock(&parent->ns->lock);
 839
 840        /* refcount released by caller */
 841        return profile;
 842}
 843
 844/**
 845 * __lookup_parent - lookup the parent of a profile of name @hname
 846 * @ns: namespace to lookup profile in  (NOT NULL)
 847 * @hname: hierarchical profile name to find parent of  (NOT NULL)
 848 *
 849 * Lookups up the parent of a fully qualified profile name, the profile
 850 * that matches hname does not need to exist, in general this
 851 * is used to load a new profile.
 852 *
 853 * Requires: ns->lock be held
 854 *
 855 * Returns: unrefcounted policy or NULL if not found
 856 */
 857static struct aa_policy *__lookup_parent(struct aa_namespace *ns,
 858                                         const char *hname)
 859{
 860        struct aa_policy *policy;
 861        struct aa_profile *profile = NULL;
 862        char *split;
 863
 864        policy = &ns->base;
 865
 866        for (split = strstr(hname, "//"); split;) {
 867                profile = __strn_find_child(&policy->profiles, hname,
 868                                            split - hname);
 869                if (!profile)
 870                        return NULL;
 871                policy = &profile->base;
 872                hname = split + 2;
 873                split = strstr(hname, "//");
 874        }
 875        if (!profile)
 876                return &ns->base;
 877        return &profile->base;
 878}
 879
 880/**
 881 * __lookup_profile - lookup the profile matching @hname
 882 * @base: base list to start looking up profile name from  (NOT NULL)
 883 * @hname: hierarchical profile name  (NOT NULL)
 884 *
 885 * Requires: ns->lock be held
 886 *
 887 * Returns: unrefcounted profile pointer or NULL if not found
 888 *
 889 * Do a relative name lookup, recursing through profile tree.
 890 */
 891static struct aa_profile *__lookup_profile(struct aa_policy *base,
 892                                           const char *hname)
 893{
 894        struct aa_profile *profile = NULL;
 895        char *split;
 896
 897        for (split = strstr(hname, "//"); split;) {
 898                profile = __strn_find_child(&base->profiles, hname,
 899                                            split - hname);
 900                if (!profile)
 901                        return NULL;
 902
 903                base = &profile->base;
 904                hname = split + 2;
 905                split = strstr(hname, "//");
 906        }
 907
 908        profile = __find_child(&base->profiles, hname);
 909
 910        return profile;
 911}
 912
 913/**
 914 * aa_lookup_profile - find a profile by its full or partial name
 915 * @ns: the namespace to start from (NOT NULL)
 916 * @hname: name to do lookup on.  Does not contain namespace prefix (NOT NULL)
 917 *
 918 * Returns: refcounted profile or NULL if not found
 919 */
 920struct aa_profile *aa_lookup_profile(struct aa_namespace *ns, const char *hname)
 921{
 922        struct aa_profile *profile;
 923
 924        read_lock(&ns->lock);
 925        profile = aa_get_profile(__lookup_profile(&ns->base, hname));
 926        read_unlock(&ns->lock);
 927
 928        /* the unconfined profile is not in the regular profile list */
 929        if (!profile && strcmp(hname, "unconfined") == 0)
 930                profile = aa_get_profile(ns->unconfined);
 931
 932        /* refcount released by caller */
 933        return profile;
 934}
 935
 936/**
 937 * replacement_allowed - test to see if replacement is allowed
 938 * @profile: profile to test if it can be replaced  (MAYBE NULL)
 939 * @noreplace: true if replacement shouldn't be allowed but addition is okay
 940 * @info: Returns - info about why replacement failed (NOT NULL)
 941 *
 942 * Returns: %0 if replacement allowed else error code
 943 */
 944static int replacement_allowed(struct aa_profile *profile, int noreplace,
 945                               const char **info)
 946{
 947        if (profile) {
 948                if (profile->flags & PFLAG_IMMUTABLE) {
 949                        *info = "cannot replace immutible profile";
 950                        return -EPERM;
 951                } else if (noreplace) {
 952                        *info = "profile already exists";
 953                        return -EEXIST;
 954                }
 955        }
 956        return 0;
 957}
 958
 959/**
 960 * __add_new_profile - simple wrapper around __list_add_profile
 961 * @ns: namespace that profile is being added to  (NOT NULL)
 962 * @policy: the policy container to add the profile to  (NOT NULL)
 963 * @profile: profile to add  (NOT NULL)
 964 *
 965 * add a profile to a list and do other required basic allocations
 966 */
 967static void __add_new_profile(struct aa_namespace *ns, struct aa_policy *policy,
 968                              struct aa_profile *profile)
 969{
 970        if (policy != &ns->base)
 971                /* released on profile replacement or free_profile */
 972                profile->parent = aa_get_profile((struct aa_profile *) policy);
 973        __list_add_profile(&policy->profiles, profile);
 974        /* released on free_profile */
 975        profile->sid = aa_alloc_sid();
 976        profile->ns = aa_get_namespace(ns);
 977}
 978
 979/**
 980 * aa_audit_policy - Do auditing of policy changes
 981 * @op: policy operation being performed
 982 * @gfp: memory allocation flags
 983 * @name: name of profile being manipulated (NOT NULL)
 984 * @info: any extra information to be audited (MAYBE NULL)
 985 * @error: error code
 986 *
 987 * Returns: the error to be returned after audit is done
 988 */
 989static int audit_policy(int op, gfp_t gfp, const char *name, const char *info,
 990                        int error)
 991{
 992        struct common_audit_data sa;
 993        struct apparmor_audit_data aad = {0,};
 994        sa.type = LSM_AUDIT_DATA_NONE;
 995        sa.aad = &aad;
 996        aad.op = op;
 997        aad.name = name;
 998        aad.info = info;
 999        aad.error = error;
1000
1001        return aa_audit(AUDIT_APPARMOR_STATUS, __aa_current_profile(), gfp,
1002                        &sa, NULL);
1003}
1004
1005/**
1006 * aa_may_manage_policy - can the current task manage policy
1007 * @op: the policy manipulation operation being done
1008 *
1009 * Returns: true if the task is allowed to manipulate policy
1010 */
1011bool aa_may_manage_policy(int op)
1012{
1013        /* check if loading policy is locked out */
1014        if (aa_g_lock_policy) {
1015                audit_policy(op, GFP_KERNEL, NULL, "policy_locked", -EACCES);
1016                return 0;
1017        }
1018
1019        if (!capable(CAP_MAC_ADMIN)) {
1020                audit_policy(op, GFP_KERNEL, NULL, "not policy admin", -EACCES);
1021                return 0;
1022        }
1023
1024        return 1;
1025}
1026
1027/**
1028 * aa_replace_profiles - replace profile(s) on the profile list
1029 * @udata: serialized data stream  (NOT NULL)
1030 * @size: size of the serialized data stream
1031 * @noreplace: true if only doing addition, no replacement allowed
1032 *
1033 * unpack and replace a profile on the profile list and uses of that profile
1034 * by any aa_task_cxt.  If the profile does not exist on the profile list
1035 * it is added.
1036 *
1037 * Returns: size of data consumed else error code on failure.
1038 */
1039ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace)
1040{
1041        struct aa_policy *policy;
1042        struct aa_profile *old_profile = NULL, *new_profile = NULL;
1043        struct aa_profile *rename_profile = NULL;
1044        struct aa_namespace *ns = NULL;
1045        const char *ns_name, *name = NULL, *info = NULL;
1046        int op = OP_PROF_REPL;
1047        ssize_t error;
1048
1049        /* released below */
1050        new_profile = aa_unpack(udata, size, &ns_name);
1051        if (IS_ERR(new_profile)) {
1052                error = PTR_ERR(new_profile);
1053                new_profile = NULL;
1054                goto fail;
1055        }
1056
1057        /* released below */
1058        ns = aa_prepare_namespace(ns_name);
1059        if (!ns) {
1060                info = "failed to prepare namespace";
1061                error = -ENOMEM;
1062                name = ns_name;
1063                goto fail;
1064        }
1065
1066        name = new_profile->base.hname;
1067
1068        write_lock(&ns->lock);
1069        /* no ref on policy only use inside lock */
1070        policy = __lookup_parent(ns, new_profile->base.hname);
1071
1072        if (!policy) {
1073                info = "parent does not exist";
1074                error = -ENOENT;
1075                goto audit;
1076        }
1077
1078        old_profile = __find_child(&policy->profiles, new_profile->base.name);
1079        /* released below */
1080        aa_get_profile(old_profile);
1081
1082        if (new_profile->rename) {
1083                rename_profile = __lookup_profile(&ns->base,
1084                                                  new_profile->rename);
1085                /* released below */
1086                aa_get_profile(rename_profile);
1087
1088                if (!rename_profile) {
1089                        info = "profile to rename does not exist";
1090                        name = new_profile->rename;
1091                        error = -ENOENT;
1092                        goto audit;
1093                }
1094        }
1095
1096        error = replacement_allowed(old_profile, noreplace, &info);
1097        if (error)
1098                goto audit;
1099
1100        error = replacement_allowed(rename_profile, noreplace, &info);
1101        if (error)
1102                goto audit;
1103
1104audit:
1105        if (!old_profile && !rename_profile)
1106                op = OP_PROF_LOAD;
1107
1108        error = audit_policy(op, GFP_ATOMIC, name, info, error);
1109
1110        if (!error) {
1111                if (rename_profile)
1112                        __replace_profile(rename_profile, new_profile);
1113                if (old_profile) {
1114                        /* when there are both rename and old profiles
1115                         * inherit old profiles sid
1116                         */
1117                        if (rename_profile)
1118                                aa_free_sid(new_profile->sid);
1119                        __replace_profile(old_profile, new_profile);
1120                }
1121                if (!(old_profile || rename_profile))
1122                        __add_new_profile(ns, policy, new_profile);
1123        }
1124        write_unlock(&ns->lock);
1125
1126out:
1127        aa_put_namespace(ns);
1128        aa_put_profile(rename_profile);
1129        aa_put_profile(old_profile);
1130        aa_put_profile(new_profile);
1131        if (error)
1132                return error;
1133        return size;
1134
1135fail:
1136        error = audit_policy(op, GFP_KERNEL, name, info, error);
1137        goto out;
1138}
1139
1140/**
1141 * aa_remove_profiles - remove profile(s) from the system
1142 * @fqname: name of the profile or namespace to remove  (NOT NULL)
1143 * @size: size of the name
1144 *
1145 * Remove a profile or sub namespace from the current namespace, so that
1146 * they can not be found anymore and mark them as replaced by unconfined
1147 *
1148 * NOTE: removing confinement does not restore rlimits to preconfinemnet values
1149 *
1150 * Returns: size of data consume else error code if fails
1151 */
1152ssize_t aa_remove_profiles(char *fqname, size_t size)
1153{
1154        struct aa_namespace *root, *ns = NULL;
1155        struct aa_profile *profile = NULL;
1156        const char *name = fqname, *info = NULL;
1157        ssize_t error = 0;
1158
1159        if (*fqname == 0) {
1160                info = "no profile specified";
1161                error = -ENOENT;
1162                goto fail;
1163        }
1164
1165        root = aa_current_profile()->ns;
1166
1167        if (fqname[0] == ':') {
1168                char *ns_name;
1169                name = aa_split_fqname(fqname, &ns_name);
1170                if (ns_name) {
1171                        /* released below */
1172                        ns = aa_find_namespace(root, ns_name);
1173                        if (!ns) {
1174                                info = "namespace does not exist";
1175                                error = -ENOENT;
1176                                goto fail;
1177                        }
1178                }
1179        } else
1180                /* released below */
1181                ns = aa_get_namespace(root);
1182
1183        if (!name) {
1184                /* remove namespace - can only happen if fqname[0] == ':' */
1185                write_lock(&ns->parent->lock);
1186                __remove_namespace(ns);
1187                write_unlock(&ns->parent->lock);
1188        } else {
1189                /* remove profile */
1190                write_lock(&ns->lock);
1191                profile = aa_get_profile(__lookup_profile(&ns->base, name));
1192                if (!profile) {
1193                        error = -ENOENT;
1194                        info = "profile does not exist";
1195                        goto fail_ns_lock;
1196                }
1197                name = profile->base.hname;
1198                __remove_profile(profile);
1199                write_unlock(&ns->lock);
1200        }
1201
1202        /* don't fail removal if audit fails */
1203        (void) audit_policy(OP_PROF_RM, GFP_KERNEL, name, info, error);
1204        aa_put_namespace(ns);
1205        aa_put_profile(profile);
1206        return size;
1207
1208fail_ns_lock:
1209        write_unlock(&ns->lock);
1210        aa_put_namespace(ns);
1211
1212fail:
1213        (void) audit_policy(OP_PROF_RM, GFP_KERNEL, name, info, error);
1214        return error;
1215}
1216
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.