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 2009-2015 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         } else
  80                 return aa_hidden_ns_name;
  81 }
  82
  83 /**
  84  * alloc_ns - allocate, initialize and return a new namespace
  85  * @prefix: parent namespace name (MAYBE NULL)
  86  * @name: a preallocated name  (NOT NULL)
  87  *
  88  * Returns: refcounted namespace or NULL on failure.
  89  */
  90 static struct aa_ns *alloc_ns(const char *prefix, const char *name)
  91 {
  92         struct aa_ns *ns;
  93
  94         ns = kzalloc(sizeof(*ns), GFP_KERNEL);
  95         AA_DEBUG("%s(%p)\n", __func__, ns);
  96         if (!ns)
  97                 return NULL;
  98         if (!aa_policy_init(&ns->base, prefix, name, GFP_KERNEL))
  99                 goto fail_ns;
 100
 101         INIT_LIST_HEAD(&ns->sub_ns);
 102         mutex_init(&ns->lock);
 103         init_waitqueue_head(&ns->wait);
 104
 105         /* released by free_namespace */
 106         ns->unconfined = aa_alloc_profile("unconfined", NULL, GFP_KERNEL);
 107         if (!ns->unconfined)
 108                 goto fail_unconfined;
 109
 110         ns->unconfined->label.flags |= FLAG_IX_ON_NAME_ERROR |
 111                 FLAG_IMMUTIBLE | FLAG_NS_COUNT | FLAG_UNCONFINED;
 112         ns->unconfined->mode = APPARMOR_UNCONFINED;
 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_find_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 static struct aa_ns *__aa_create_ns(struct aa_ns *parent, const char *name,
 189                                     struct dentry *dir)
 190 {
 191         struct aa_ns *ns;
 192         int error;
 193
 194         AA_BUG(!parent);
 195         AA_BUG(!name);
 196         AA_BUG(!mutex_is_locked(&parent->lock));
 197
 198         ns = alloc_ns(parent->base.hname, name);
 199         if (!ns)
 200                 return NULL;
 201         mutex_lock(&ns->lock);
 202         error = __aa_fs_ns_mkdir(ns, ns_subns_dir(parent), name, dir);
 203         if (error) {
 204                 AA_ERROR("Failed to create interface for ns %s\n",
 205                          ns->base.name);
 206                 mutex_unlock(&ns->lock);
 207                 aa_free_ns(ns);
 208                 return ERR_PTR(error);
 209         } else {
 210                 ns->parent = aa_get_ns(parent);
 211                 ns->level = parent->level + 1;
 212                 list_add_rcu(&ns->base.list, &parent->sub_ns);
 213                 /* add list ref */
 214                 aa_get_ns(ns);
 215         }
 216         mutex_unlock(&ns->lock);
 217
 218         return ns;
 219 }
 220
 221 /**
 222  * aa_create_ns - create an ns, fail if it already exists
 223  * @parent: the parent of the namespace being created
 224  * @name: the name of the namespace
 225  * @dir: if not null the dir to put the ns entries in
 226  *
 227  * Returns: the a refcounted ns that has been add or an ERR_PTR
 228  */
 229 struct aa_ns *aa_create_ns(struct aa_ns *parent, const char *name,
 230                            struct dentry *dir)
 231 {
 232         struct aa_ns *ns;
 233
 234         mutex_lock(&parent->lock);
 235         /* try and find the specified ns */
 236         /* released by caller */
 237         ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
 238         if (!ns)
 239                 ns = __aa_create_ns(parent, name, dir);
 240         else
 241                 ns = ERR_PTR(-EEXIST);
 242         mutex_unlock(&parent->lock);
 243
 244         /* return ref */
 245         return ns;
 246 }
 247
 248 /**
 249  * aa_prepare_ns - find an existing or create a new namespace of @name
 250  * @parent: ns to treat as parent
 251  * @name: the namespace to find or add  (NOT NULL)
 252  *
 253  * Returns: refcounted namespace or PTR_ERR if failed to create one
 254  */
 255 struct aa_ns *aa_prepare_ns(struct aa_ns *parent, const char *name)
 256 {
 257         struct aa_ns *ns;
 258
 259         mutex_lock(&parent->lock);
 260         /* try and find the specified ns and if it doesn't exist create it */
 261         /* released by caller */
 262         ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
 263         if (!ns)
 264                 ns = __aa_create_ns(parent, name, NULL);
 265         mutex_unlock(&parent->lock);
 266
 267         /* return ref */
 268         return ns;
 269 }
 270
 271 static void __ns_list_release(struct list_head *head);
 272
 273 /**
 274  * destroy_namespace - remove everything contained by @ns
 275  * @ns: namespace to have it contents removed  (NOT NULL)
 276  */
 277 static void destroy_ns(struct aa_ns *ns)
 278 {
 279         if (!ns)
 280                 return;
 281
 282         mutex_lock(&ns->lock);
 283         /* release all profiles in this namespace */
 284         __aa_profile_list_release(&ns->base.profiles);
 285
 286         /* release all sub namespaces */
 287         __ns_list_release(&ns->sub_ns);
 288
 289         if (ns->parent) {
 290                 unsigned long flags;
 291                 write_lock_irqsave(&ns->labels.lock, flags);
 292                 __aa_proxy_redirect(ns_unconfined(ns),
 293                                     ns_unconfined(ns->parent));
 294                 write_unlock_irqrestore(&ns->labels.lock, flags);
 295         }
 296         __aa_fs_ns_rmdir(ns);
 297         mutex_unlock(&ns->lock);
 298 }
 299
 300 /**
 301  * __aa_remove_ns - remove a namespace and all its children
 302  * @ns: namespace to be removed  (NOT NULL)
 303  *
 304  * Requires: ns->parent->lock be held and ns removed from parent.
 305  */
 306 void __aa_remove_ns(struct aa_ns *ns)
 307 {
 308         /* remove ns from namespace list */
 309         list_del_rcu(&ns->base.list);
 310         destroy_ns(ns);
 311         aa_put_ns(ns);
 312 }
 313
 314 /**
 315  * __ns_list_release - remove all profile namespaces on the list put refs
 316  * @head: list of profile namespaces  (NOT NULL)
 317  *
 318  * Requires: namespace lock be held
 319  */
 320 static void __ns_list_release(struct list_head *head)
 321 {
 322         struct aa_ns *ns, *tmp;
 323         list_for_each_entry_safe(ns, tmp, head, base.list)
 324                 __aa_remove_ns(ns);
 325
 326 }
 327
 328 /**
 329  * aa_alloc_root_ns - allocate the root profile namespace
 330  *
 331  * Returns: %0 on success else error
 332  *
 333  */
 334 int __init aa_alloc_root_ns(void)
 335 {
 336         /* released by aa_free_root_ns - used as list ref*/
 337         root_ns = alloc_ns(NULL, "root");
 338         if (!root_ns)
 339                 return -ENOMEM;
 340
 341         return 0;
 342 }
 343
 344  /**
 345   * aa_free_root_ns - free the root profile namespace
 346   */
 347 void __init aa_free_root_ns(void)
 348  {
 349          struct aa_ns *ns = root_ns;
 350          root_ns = NULL;
 351
 352          destroy_ns(ns);
 353          aa_put_ns(ns);
 354 }