security/apparmor/policy_ns.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor policy manipulation functions
   5  *
   6  * Copyright (C) 1998-2008 Novell/SUSE
   7  * Copyright 2009-2017 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  * AppArmor policy namespaces, allow for different sets of policies
  15  * to be loaded for tasks within the namespace.
  16  */
  17
  18 #include <linux/list.h>
  19 #include <linux/mutex.h>
  20 #include <linux/slab.h>
  21 #include <linux/string.h>
  22
  23 #include "include/apparmor.h"
  24 #include "include/context.h"
  25 #include "include/policy_ns.h"
  26 #include "include/label.h"
  27 #include "include/policy.h"
  28
  29 /* root profile namespace */
  30 struct aa_ns *root_ns;
  31 const char *aa_hidden_ns_name = "---";
  32
  33 /**
  34  * aa_ns_visible - test if @view is visible from @curr
  35  * @curr: namespace to treat as the parent (NOT NULL)
  36  * @view: namespace to test if visible from @curr (NOT NULL)
  37  * @subns: whether view of a subns is allowed
  38  *
  39  * Returns: true if @view is visible from @curr else false
  40  */
  41 bool aa_ns_visible(struct aa_ns *curr, struct aa_ns *view, bool subns)
  42 {
  43         if (curr == view)
  44                 return true;
  45
  46         if (!subns)
  47                 return false;
  48
  49         for ( ; view; view = view->parent) {
  50                 if (view->parent == curr)
  51                         return true;
  52         }
  53
  54         return false;
  55 }
  56
  57 /**
  58  * aa_na_name - Find the ns name to display for @view from @curr
  59  * @curr - current namespace (NOT NULL)
  60  * @view - namespace attempting to view (NOT NULL)
  61  * @subns - are subns visible
  62  *
  63  * Returns: name of @view visible from @curr
  64  */
  65 const char *aa_ns_name(struct aa_ns *curr, struct aa_ns *view, bool subns)
  66 {
  67         /* if view == curr then the namespace name isn't displayed */
  68         if (curr == view)
  69                 return "";
  70
  71         if (aa_ns_visible(curr, view, subns)) {
  72                 /* at this point if a ns is visible it is in a view ns
  73                  * thus the curr ns.hname is a prefix of its name.
  74                  * Only output the virtualized portion of the name
  75                  * Add + 2 to skip over // separating curr hname prefix
  76                  * from the visible tail of the views hname
  77                  */
  78                 return view->base.hname + strlen(curr->base.hname) + 2;
  79         }
  80
  81         return aa_hidden_ns_name;
  82 }
  83
  84 /**
  85  * alloc_ns - allocate, initialize and return a new namespace
  86  * @prefix: parent namespace name (MAYBE NULL)
  87  * @name: a preallocated name  (NOT NULL)
  88  *
  89  * Returns: refcounted namespace or NULL on failure.
  90  */
  91 static struct aa_ns *alloc_ns(const char *prefix, const char *name)
  92 {
  93         struct aa_ns *ns;
  94
  95         ns = kzalloc(sizeof(*ns), GFP_KERNEL);
  96         AA_DEBUG("%s(%p)\n", __func__, ns);
  97         if (!ns)
  98                 return NULL;
  99         if (!aa_policy_init(&ns->base, prefix, name, GFP_KERNEL))
 100                 goto fail_ns;
 101
 102         INIT_LIST_HEAD(&ns->sub_ns);
 103         INIT_LIST_HEAD(&ns->rawdata_list);
 104         mutex_init(&ns->lock);
 105         init_waitqueue_head(&ns->wait);
 106
 107         /* released by aa_free_ns() */
 108         ns->unconfined = aa_alloc_profile("unconfined", NULL, GFP_KERNEL);
 109         if (!ns->unconfined)
 110                 goto fail_unconfined;
 111
 112         ns->unconfined->label.flags |= FLAG_IX_ON_NAME_ERROR |
 113                 FLAG_IMMUTIBLE | FLAG_NS_COUNT | FLAG_UNCONFINED;
 114         ns->unconfined->mode = APPARMOR_UNCONFINED;
 115
 116         /* ns and ns->unconfined share ns->unconfined refcount */
 117         ns->unconfined->ns = ns;
 118
 119         atomic_set(&ns->uniq_null, 0);
 120
 121         aa_labelset_init(&ns->labels);
 122
 123         return ns;
 124
 125 fail_unconfined:
 126         kzfree(ns->base.hname);
 127 fail_ns:
 128         kzfree(ns);
 129         return NULL;
 130 }
 131
 132 /**
 133  * aa_free_ns - free a profile namespace
 134  * @ns: the namespace to free  (MAYBE NULL)
 135  *
 136  * Requires: All references to the namespace must have been put, if the
 137  *           namespace was referenced by a profile confining a task,
 138  */
 139 void aa_free_ns(struct aa_ns *ns)
 140 {
 141         if (!ns)
 142                 return;
 143
 144         aa_policy_destroy(&ns->base);
 145         aa_labelset_destroy(&ns->labels);
 146         aa_put_ns(ns->parent);
 147
 148         ns->unconfined->ns = NULL;
 149         aa_free_profile(ns->unconfined);
 150         kzfree(ns);
 151 }
 152
 153 /**
 154  * aa_findn_ns  -  look up a profile namespace on the namespace list
 155  * @root: namespace to search in  (NOT NULL)
 156  * @name: name of namespace to find  (NOT NULL)
 157  * @n: length of @name
 158  *
 159  * Returns: a refcounted namespace on the list, or NULL if no namespace
 160  *          called @name exists.
 161  *
 162  * refcount released by caller
 163  */
 164 struct aa_ns *aa_findn_ns(struct aa_ns *root, const char *name, size_t n)
 165 {
 166         struct aa_ns *ns = NULL;
 167
 168         rcu_read_lock();
 169         ns = aa_get_ns(__aa_findn_ns(&root->sub_ns, name, n));
 170         rcu_read_unlock();
 171
 172         return ns;
 173 }
 174
 175 /**
 176  * aa_find_ns  -  look up a profile namespace on the namespace list
 177  * @root: namespace to search in  (NOT NULL)
 178  * @name: name of namespace to find  (NOT NULL)
 179  *
 180  * Returns: a refcounted namespace on the list, or NULL if no namespace
 181  *          called @name exists.
 182  *
 183  * refcount released by caller
 184  */
 185 struct aa_ns *aa_find_ns(struct aa_ns *root, const char *name)
 186 {
 187         return aa_findn_ns(root, name, strlen(name));
 188 }
 189
 190 /**
 191  * __aa_lookupn_ns - lookup the namespace matching @hname
 192  * @base: base list to start looking up profile name from  (NOT NULL)
 193  * @hname: hierarchical ns name  (NOT NULL)
 194  * @n: length of @hname
 195  *
 196  * Requires: rcu_read_lock be held
 197  *
 198  * Returns: unrefcounted ns pointer or NULL if not found
 199  *
 200  * Do a relative name lookup, recursing through profile tree.
 201  */
 202 struct aa_ns *__aa_lookupn_ns(struct aa_ns *view, const char *hname, size_t n)
 203 {
 204         struct aa_ns *ns = view;
 205         const char *split;
 206
 207         for (split = strnstr(hname, "//", n); split;
 208              split = strnstr(hname, "//", n)) {
 209                 ns = __aa_findn_ns(&ns->sub_ns, hname, split - hname);
 210                 if (!ns)
 211                         return NULL;
 212
 213                 n -= split + 2 - hname;
 214                 hname = split + 2;
 215         }
 216
 217         if (n)
 218                 return __aa_findn_ns(&ns->sub_ns, hname, n);
 219         return NULL;
 220 }
 221
 222 /**
 223  * aa_lookupn_ns  -  look up a policy namespace relative to @view
 224  * @view: namespace to search in  (NOT NULL)
 225  * @name: name of namespace to find  (NOT NULL)
 226  * @n: length of @name
 227  *
 228  * Returns: a refcounted namespace on the list, or NULL if no namespace
 229  *          called @name exists.
 230  *
 231  * refcount released by caller
 232  */
 233 struct aa_ns *aa_lookupn_ns(struct aa_ns *view, const char *name, size_t n)
 234 {
 235         struct aa_ns *ns = NULL;
 236
 237         rcu_read_lock();
 238         ns = aa_get_ns(__aa_lookupn_ns(view, name, n));
 239         rcu_read_unlock();
 240
 241         return ns;
 242 }
 243
 244 static struct aa_ns *__aa_create_ns(struct aa_ns *parent, const char *name,
 245                                     struct dentry *dir)
 246 {
 247         struct aa_ns *ns;
 248         int error;
 249
 250         AA_BUG(!parent);
 251         AA_BUG(!name);
 252         AA_BUG(!mutex_is_locked(&parent->lock));
 253
 254         ns = alloc_ns(parent->base.hname, name);
 255         if (!ns)
 256                 return NULL;
 257         mutex_lock(&ns->lock);
 258         error = __aafs_ns_mkdir(ns, ns_subns_dir(parent), name, dir);
 259         if (error) {
 260                 AA_ERROR("Failed to create interface for ns %s\n",
 261                          ns->base.name);
 262                 mutex_unlock(&ns->lock);
 263                 aa_free_ns(ns);
 264                 return ERR_PTR(error);
 265         }
 266         ns->parent = aa_get_ns(parent);
 267         ns->level = parent->level + 1;
 268         list_add_rcu(&ns->base.list, &parent->sub_ns);
 269         /* add list ref */
 270         aa_get_ns(ns);
 271         mutex_unlock(&ns->lock);
 272
 273         return ns;
 274 }
 275
 276 /**
 277  * aa_create_ns - create an ns, fail if it already exists
 278  * @parent: the parent of the namespace being created
 279  * @name: the name of the namespace
 280  * @dir: if not null the dir to put the ns entries in
 281  *
 282  * Returns: the a refcounted ns that has been add or an ERR_PTR
 283  */
 284 struct aa_ns *__aa_find_or_create_ns(struct aa_ns *parent, const char *name,
 285                                      struct dentry *dir)
 286 {
 287         struct aa_ns *ns;
 288
 289         AA_BUG(!mutex_is_locked(&parent->lock));
 290
 291         /* try and find the specified ns */
 292         /* released by caller */
 293         ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
 294         if (!ns)
 295                 ns = __aa_create_ns(parent, name, dir);
 296         else
 297                 ns = ERR_PTR(-EEXIST);
 298
 299         /* return ref */
 300         return ns;
 301 }
 302
 303 /**
 304  * aa_prepare_ns - find an existing or create a new namespace of @name
 305  * @parent: ns to treat as parent
 306  * @name: the namespace to find or add  (NOT NULL)
 307  *
 308  * Returns: refcounted namespace or PTR_ERR if failed to create one
 309  */
 310 struct aa_ns *aa_prepare_ns(struct aa_ns *parent, const char *name)
 311 {
 312         struct aa_ns *ns;
 313
 314         mutex_lock(&parent->lock);
 315         /* try and find the specified ns and if it doesn't exist create it */
 316         /* released by caller */
 317         ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
 318         if (!ns)
 319                 ns = __aa_create_ns(parent, name, NULL);
 320         mutex_unlock(&parent->lock);
 321
 322         /* return ref */
 323         return ns;
 324 }
 325
 326 static void __ns_list_release(struct list_head *head);
 327
 328 /**
 329  * destroy_ns - remove everything contained by @ns
 330  * @ns: namespace to have it contents removed  (NOT NULL)
 331  */
 332 static void destroy_ns(struct aa_ns *ns)
 333 {
 334         if (!ns)
 335                 return;
 336
 337         mutex_lock(&ns->lock);
 338         /* release all profiles in this namespace */
 339         __aa_profile_list_release(&ns->base.profiles);
 340
 341         /* release all sub namespaces */
 342         __ns_list_release(&ns->sub_ns);
 343
 344         if (ns->parent) {
 345                 unsigned long flags;
 346
 347                 write_lock_irqsave(&ns->labels.lock, flags);
 348                 __aa_proxy_redirect(ns_unconfined(ns),
 349                                     ns_unconfined(ns->parent));
 350                 write_unlock_irqrestore(&ns->labels.lock, flags);
 351         }
 352         __aafs_ns_rmdir(ns);
 353         mutex_unlock(&ns->lock);
 354 }
 355
 356 /**
 357  * __aa_remove_ns - remove a namespace and all its children
 358  * @ns: namespace to be removed  (NOT NULL)
 359  *
 360  * Requires: ns->parent->lock be held and ns removed from parent.
 361  */
 362 void __aa_remove_ns(struct aa_ns *ns)
 363 {
 364         /* remove ns from namespace list */
 365         list_del_rcu(&ns->base.list);
 366         destroy_ns(ns);
 367         aa_put_ns(ns);
 368 }
 369
 370 /**
 371  * __ns_list_release - remove all profile namespaces on the list put refs
 372  * @head: list of profile namespaces  (NOT NULL)
 373  *
 374  * Requires: namespace lock be held
 375  */
 376 static void __ns_list_release(struct list_head *head)
 377 {
 378         struct aa_ns *ns, *tmp;
 379
 380         list_for_each_entry_safe(ns, tmp, head, base.list)
 381                 __aa_remove_ns(ns);
 382
 383 }
 384
 385 /**
 386  * aa_alloc_root_ns - allocate the root profile namespace
 387  *
 388  * Returns: %0 on success else error
 389  *
 390  */
 391 int __init aa_alloc_root_ns(void)
 392 {
 393         /* released by aa_free_root_ns - used as list ref*/
 394         root_ns = alloc_ns(NULL, "root");
 395         if (!root_ns)
 396                 return -ENOMEM;
 397
 398         return 0;
 399 }
 400
 401  /**
 402   * aa_free_root_ns - free the root profile namespace
 403   */
 404 void __init aa_free_root_ns(void)
 405 {
 406          struct aa_ns *ns = root_ns;
 407
 408          root_ns = NULL;
 409
 410          destroy_ns(ns);
 411          aa_put_ns(ns);
 412 }