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  */
aa_ns_visible(struct aa_ns * curr,struct aa_ns * view,bool subns)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  */
aa_ns_name(struct aa_ns * curr,struct aa_ns * view,bool subns)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  */
alloc_ns(const char * prefix,const char * name)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  */
aa_free_ns(struct aa_ns * ns)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  */
aa_findn_ns(struct aa_ns * root,const char * name,size_t n)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  */
aa_find_ns(struct aa_ns * root,const char * name)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  */
__aa_lookupn_ns(struct aa_ns * view,const char * hname,size_t n)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  */
aa_lookupn_ns(struct aa_ns * view,const char * name,size_t n)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 
__aa_create_ns(struct aa_ns * parent,const char * name,struct dentry * dir)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  */
__aa_find_or_create_ns(struct aa_ns * parent,const char * name,struct dentry * dir)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  */
aa_prepare_ns(struct aa_ns * parent,const char * name)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  */
destroy_ns(struct aa_ns * ns)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  */
__aa_remove_ns(struct aa_ns * ns)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  */
__ns_list_release(struct list_head * head)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  */
aa_alloc_root_ns(void)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   */
aa_free_root_ns(void)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