security/apparmor/policy_ns.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor policy manipulation functions
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2017 Canonical Ltd.
   9  *
  10  * AppArmor policy namespaces, allow for different sets of policies
  11  * to be loaded for tasks within the namespace.
  12  */
  13
  14 #include <linux/list.h>
  15 #include <linux/mutex.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18
  19 #include "include/apparmor.h"
  20 #include "include/cred.h"
  21 #include "include/policy_ns.h"
  22 #include "include/label.h"
  23 #include "include/policy.h"
  24
  25 /* root profile namespace */
  26 struct aa_ns *root_ns;
  27 const char *aa_hidden_ns_name = "---";
  28
  29 /**
  30  * aa_ns_visible - test if @view is visible from @curr
  31  * @curr: namespace to treat as the parent (NOT NULL)
  32  * @view: namespace to test if visible from @curr (NOT NULL)
  33  * @subns: whether view of a subns is allowed
  34  *
  35  * Returns: true if @view is visible from @curr else false
  36  */
  37 bool aa_ns_visible(struct aa_ns *curr, struct aa_ns *view, bool subns)
  38 {
  39         if (curr == view)
  40                 return true;
  41
  42         if (!subns)
  43                 return false;
  44
  45         for ( ; view; view = view->parent) {
  46                 if (view->parent == curr)
  47                         return true;
  48         }
  49
  50         return false;
  51 }
  52
  53 /**
  54  * aa_na_name - Find the ns name to display for @view from @curr
  55  * @curr - current namespace (NOT NULL)
  56  * @view - namespace attempting to view (NOT NULL)
  57  * @subns - are subns visible
  58  *
  59  * Returns: name of @view visible from @curr
  60  */
  61 const char *aa_ns_name(struct aa_ns *curr, struct aa_ns *view, bool subns)
  62 {
  63         /* if view == curr then the namespace name isn't displayed */
  64         if (curr == view)
  65                 return "";
  66
  67         if (aa_ns_visible(curr, view, subns)) {
  68                 /* at this point if a ns is visible it is in a view ns
  69                  * thus the curr ns.hname is a prefix of its name.
  70                  * Only output the virtualized portion of the name
  71                  * Add + 2 to skip over // separating curr hname prefix
  72                  * from the visible tail of the views hname
  73                  */
  74                 return view->base.hname + strlen(curr->base.hname) + 2;
  75         }
  76
  77         return aa_hidden_ns_name;
  78 }
  79
  80 /**
  81  * alloc_ns - allocate, initialize and return a new namespace
  82  * @prefix: parent namespace name (MAYBE NULL)
  83  * @name: a preallocated name  (NOT NULL)
  84  *
  85  * Returns: refcounted namespace or NULL on failure.
  86  */
  87 static struct aa_ns *alloc_ns(const char *prefix, const char *name)
  88 {
  89         struct aa_ns *ns;
  90
  91         ns = kzalloc(sizeof(*ns), GFP_KERNEL);
  92         AA_DEBUG("%s(%p)\n", __func__, ns);
  93         if (!ns)
  94                 return NULL;
  95         if (!aa_policy_init(&ns->base, prefix, name, GFP_KERNEL))
  96                 goto fail_ns;
  97
  98         INIT_LIST_HEAD(&ns->sub_ns);
  99         INIT_LIST_HEAD(&ns->rawdata_list);
 100         mutex_init(&ns->lock);
 101         init_waitqueue_head(&ns->wait);
 102
 103         /* released by aa_free_ns() */
 104         ns->unconfined = aa_alloc_profile("unconfined", NULL, GFP_KERNEL);
 105         if (!ns->unconfined)
 106                 goto fail_unconfined;
 107
 108         ns->unconfined->label.flags |= FLAG_IX_ON_NAME_ERROR |
 109                 FLAG_IMMUTIBLE | FLAG_NS_COUNT | FLAG_UNCONFINED;
 110         ns->unconfined->mode = APPARMOR_UNCONFINED;
 111         ns->unconfined->file.dfa = aa_get_dfa(nulldfa);
 112         ns->unconfined->policy.dfa = aa_get_dfa(nulldfa);
 113
 114         /* ns and ns->unconfined share ns->unconfined refcount */
 115         ns->unconfined->ns = ns;
 116
 117         atomic_set(&ns->uniq_null, 0);
 118
 119         aa_labelset_init(&ns->labels);
 120
 121         return ns;
 122
 123 fail_unconfined:
 124         kzfree(ns->base.hname);
 125 fail_ns:
 126         kzfree(ns);
 127         return NULL;
 128 }
 129
 130 /**
 131  * aa_free_ns - free a profile namespace
 132  * @ns: the namespace to free  (MAYBE NULL)
 133  *
 134  * Requires: All references to the namespace must have been put, if the
 135  *           namespace was referenced by a profile confining a task,
 136  */
 137 void aa_free_ns(struct aa_ns *ns)
 138 {
 139         if (!ns)
 140                 return;
 141
 142         aa_policy_destroy(&ns->base);
 143         aa_labelset_destroy(&ns->labels);
 144         aa_put_ns(ns->parent);
 145
 146         ns->unconfined->ns = NULL;
 147         aa_free_profile(ns->unconfined);
 148         kzfree(ns);
 149 }
 150
 151 /**
 152  * aa_findn_ns  -  look up a profile namespace on the namespace list
 153  * @root: namespace to search in  (NOT NULL)
 154  * @name: name of namespace to find  (NOT NULL)
 155  * @n: length of @name
 156  *
 157  * Returns: a refcounted namespace on the list, or NULL if no namespace
 158  *          called @name exists.
 159  *
 160  * refcount released by caller
 161  */
 162 struct aa_ns *aa_findn_ns(struct aa_ns *root, const char *name, size_t n)
 163 {
 164         struct aa_ns *ns = NULL;
 165
 166         rcu_read_lock();
 167         ns = aa_get_ns(__aa_findn_ns(&root->sub_ns, name, n));
 168         rcu_read_unlock();
 169
 170         return ns;
 171 }
 172
 173 /**
 174  * aa_find_ns  -  look up a profile namespace on the namespace list
 175  * @root: namespace to search in  (NOT NULL)
 176  * @name: name of namespace to find  (NOT NULL)
 177  *
 178  * Returns: a refcounted namespace on the list, or NULL if no namespace
 179  *          called @name exists.
 180  *
 181  * refcount released by caller
 182  */
 183 struct aa_ns *aa_find_ns(struct aa_ns *root, const char *name)
 184 {
 185         return aa_findn_ns(root, name, strlen(name));
 186 }
 187
 188 /**
 189  * __aa_lookupn_ns - lookup the namespace matching @hname
 190  * @base: base list to start looking up profile name from  (NOT NULL)
 191  * @hname: hierarchical ns name  (NOT NULL)
 192  * @n: length of @hname
 193  *
 194  * Requires: rcu_read_lock be held
 195  *
 196  * Returns: unrefcounted ns pointer or NULL if not found
 197  *
 198  * Do a relative name lookup, recursing through profile tree.
 199  */
 200 struct aa_ns *__aa_lookupn_ns(struct aa_ns *view, const char *hname, size_t n)
 201 {
 202         struct aa_ns *ns = view;
 203         const char *split;
 204
 205         for (split = strnstr(hname, "//", n); split;
 206              split = strnstr(hname, "//", n)) {
 207                 ns = __aa_findn_ns(&ns->sub_ns, hname, split - hname);
 208                 if (!ns)
 209                         return NULL;
 210
 211                 n -= split + 2 - hname;
 212                 hname = split + 2;
 213         }
 214
 215         if (n)
 216                 return __aa_findn_ns(&ns->sub_ns, hname, n);
 217         return NULL;
 218 }
 219
 220 /**
 221  * aa_lookupn_ns  -  look up a policy namespace relative to @view
 222  * @view: namespace to search in  (NOT NULL)
 223  * @name: name of namespace to find  (NOT NULL)
 224  * @n: length of @name
 225  *
 226  * Returns: a refcounted namespace on the list, or NULL if no namespace
 227  *          called @name exists.
 228  *
 229  * refcount released by caller
 230  */
 231 struct aa_ns *aa_lookupn_ns(struct aa_ns *view, const char *name, size_t n)
 232 {
 233         struct aa_ns *ns = NULL;
 234
 235         rcu_read_lock();
 236         ns = aa_get_ns(__aa_lookupn_ns(view, name, n));
 237         rcu_read_unlock();
 238
 239         return ns;
 240 }
 241
 242 static struct aa_ns *__aa_create_ns(struct aa_ns *parent, const char *name,
 243                                     struct dentry *dir)
 244 {
 245         struct aa_ns *ns;
 246         int error;
 247
 248         AA_BUG(!parent);
 249         AA_BUG(!name);
 250         AA_BUG(!mutex_is_locked(&parent->lock));
 251
 252         ns = alloc_ns(parent->base.hname, name);
 253         if (!ns)
 254                 return ERR_PTR(-ENOMEM);
 255         ns->level = parent->level + 1;
 256         mutex_lock_nested(&ns->lock, ns->level);
 257         error = __aafs_ns_mkdir(ns, ns_subns_dir(parent), name, dir);
 258         if (error) {
 259                 AA_ERROR("Failed to create interface for ns %s\n",
 260                          ns->base.name);
 261                 mutex_unlock(&ns->lock);
 262                 aa_free_ns(ns);
 263                 return ERR_PTR(error);
 264         }
 265         ns->parent = aa_get_ns(parent);
 266         list_add_rcu(&ns->base.list, &parent->sub_ns);
 267         /* add list ref */
 268         aa_get_ns(ns);
 269         mutex_unlock(&ns->lock);
 270
 271         return ns;
 272 }
 273
 274 /**
 275  * aa_create_ns - create an ns, fail if it already exists
 276  * @parent: the parent of the namespace being created
 277  * @name: the name of the namespace
 278  * @dir: if not null the dir to put the ns entries in
 279  *
 280  * Returns: the a refcounted ns that has been add or an ERR_PTR
 281  */
 282 struct aa_ns *__aa_find_or_create_ns(struct aa_ns *parent, const char *name,
 283                                      struct dentry *dir)
 284 {
 285         struct aa_ns *ns;
 286
 287         AA_BUG(!mutex_is_locked(&parent->lock));
 288
 289         /* try and find the specified ns */
 290         /* released by caller */
 291         ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
 292         if (!ns)
 293                 ns = __aa_create_ns(parent, name, dir);
 294         else
 295                 ns = ERR_PTR(-EEXIST);
 296
 297         /* return ref */
 298         return ns;
 299 }
 300
 301 /**
 302  * aa_prepare_ns - find an existing or create a new namespace of @name
 303  * @parent: ns to treat as parent
 304  * @name: the namespace to find or add  (NOT NULL)
 305  *
 306  * Returns: refcounted namespace or PTR_ERR if failed to create one
 307  */
 308 struct aa_ns *aa_prepare_ns(struct aa_ns *parent, const char *name)
 309 {
 310         struct aa_ns *ns;
 311
 312         mutex_lock_nested(&parent->lock, parent->level);
 313         /* try and find the specified ns and if it doesn't exist create it */
 314         /* released by caller */
 315         ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
 316         if (!ns)
 317                 ns = __aa_create_ns(parent, name, NULL);
 318         mutex_unlock(&parent->lock);
 319
 320         /* return ref */
 321         return ns;
 322 }
 323
 324 static void __ns_list_release(struct list_head *head);
 325
 326 /**
 327  * destroy_ns - remove everything contained by @ns
 328  * @ns: namespace to have it contents removed  (NOT NULL)
 329  */
 330 static void destroy_ns(struct aa_ns *ns)
 331 {
 332         if (!ns)
 333                 return;
 334
 335         mutex_lock_nested(&ns->lock, ns->level);
 336         /* release all profiles in this namespace */
 337         __aa_profile_list_release(&ns->base.profiles);
 338
 339         /* release all sub namespaces */
 340         __ns_list_release(&ns->sub_ns);
 341
 342         if (ns->parent) {
 343                 unsigned long flags;
 344
 345                 write_lock_irqsave(&ns->labels.lock, flags);
 346                 __aa_proxy_redirect(ns_unconfined(ns),
 347                                     ns_unconfined(ns->parent));
 348                 write_unlock_irqrestore(&ns->labels.lock, flags);
 349         }
 350         __aafs_ns_rmdir(ns);
 351         mutex_unlock(&ns->lock);
 352 }
 353
 354 /**
 355  * __aa_remove_ns - remove a namespace and all its children
 356  * @ns: namespace to be removed  (NOT NULL)
 357  *
 358  * Requires: ns->parent->lock be held and ns removed from parent.
 359  */
 360 void __aa_remove_ns(struct aa_ns *ns)
 361 {
 362         /* remove ns from namespace list */
 363         list_del_rcu(&ns->base.list);
 364         destroy_ns(ns);
 365         aa_put_ns(ns);
 366 }
 367
 368 /**
 369  * __ns_list_release - remove all profile namespaces on the list put refs
 370  * @head: list of profile namespaces  (NOT NULL)
 371  *
 372  * Requires: namespace lock be held
 373  */
 374 static void __ns_list_release(struct list_head *head)
 375 {
 376         struct aa_ns *ns, *tmp;
 377
 378         list_for_each_entry_safe(ns, tmp, head, base.list)
 379                 __aa_remove_ns(ns);
 380
 381 }
 382
 383 /**
 384  * aa_alloc_root_ns - allocate the root profile namespace
 385  *
 386  * Returns: %0 on success else error
 387  *
 388  */
 389 int __init aa_alloc_root_ns(void)
 390 {
 391         /* released by aa_free_root_ns - used as list ref*/
 392         root_ns = alloc_ns(NULL, "root");
 393         if (!root_ns)
 394                 return -ENOMEM;
 395
 396         return 0;
 397 }
 398
 399  /**
 400   * aa_free_root_ns - free the root profile namespace
 401   */
 402 void __init aa_free_root_ns(void)
 403 {
 404          struct aa_ns *ns = root_ns;
 405
 406          root_ns = NULL;
 407
 408          destroy_ns(ns);
 409          aa_put_ns(ns);
 410 }