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Linux/security/apparmor/policy_ns.c

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  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         kfree_sensitive(ns->base.hname);
125 fail_ns:
126         kfree_sensitive(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         kfree_sensitive(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 }
411 

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