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