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 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 */
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 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 */
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