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847b173e TH |
1 | /* |
2 | * security/tomoyo/gc.c | |
3 | * | |
4 | * Implementation of the Domain-Based Mandatory Access Control. | |
5 | * | |
6 | * Copyright (C) 2005-2010 NTT DATA CORPORATION | |
7 | * | |
8 | */ | |
9 | ||
10 | #include "common.h" | |
11 | #include <linux/kthread.h> | |
5a0e3ad6 | 12 | #include <linux/slab.h> |
847b173e TH |
13 | |
14 | enum tomoyo_gc_id { | |
15 | TOMOYO_ID_DOMAIN_INITIALIZER, | |
16 | TOMOYO_ID_DOMAIN_KEEPER, | |
17 | TOMOYO_ID_ALIAS, | |
18 | TOMOYO_ID_GLOBALLY_READABLE, | |
19 | TOMOYO_ID_PATTERN, | |
20 | TOMOYO_ID_NO_REWRITE, | |
21 | TOMOYO_ID_MANAGER, | |
22 | TOMOYO_ID_NAME, | |
23 | TOMOYO_ID_ACL, | |
24 | TOMOYO_ID_DOMAIN | |
25 | }; | |
26 | ||
27 | struct tomoyo_gc_entry { | |
28 | struct list_head list; | |
29 | int type; | |
30 | void *element; | |
31 | }; | |
32 | static LIST_HEAD(tomoyo_gc_queue); | |
33 | static DEFINE_MUTEX(tomoyo_gc_mutex); | |
34 | ||
35 | /* Caller holds tomoyo_policy_lock mutex. */ | |
36 | static bool tomoyo_add_to_gc(const int type, void *element) | |
37 | { | |
38 | struct tomoyo_gc_entry *entry = kzalloc(sizeof(*entry), GFP_ATOMIC); | |
39 | if (!entry) | |
40 | return false; | |
41 | entry->type = type; | |
42 | entry->element = element; | |
43 | list_add(&entry->list, &tomoyo_gc_queue); | |
44 | return true; | |
45 | } | |
46 | ||
47 | static void tomoyo_del_allow_read | |
48 | (struct tomoyo_globally_readable_file_entry *ptr) | |
49 | { | |
50 | tomoyo_put_name(ptr->filename); | |
51 | } | |
52 | ||
53 | static void tomoyo_del_file_pattern(struct tomoyo_pattern_entry *ptr) | |
54 | { | |
55 | tomoyo_put_name(ptr->pattern); | |
56 | } | |
57 | ||
58 | static void tomoyo_del_no_rewrite(struct tomoyo_no_rewrite_entry *ptr) | |
59 | { | |
60 | tomoyo_put_name(ptr->pattern); | |
61 | } | |
62 | ||
63 | static void tomoyo_del_domain_initializer | |
64 | (struct tomoyo_domain_initializer_entry *ptr) | |
65 | { | |
66 | tomoyo_put_name(ptr->domainname); | |
67 | tomoyo_put_name(ptr->program); | |
68 | } | |
69 | ||
70 | static void tomoyo_del_domain_keeper(struct tomoyo_domain_keeper_entry *ptr) | |
71 | { | |
72 | tomoyo_put_name(ptr->domainname); | |
73 | tomoyo_put_name(ptr->program); | |
74 | } | |
75 | ||
76 | static void tomoyo_del_alias(struct tomoyo_alias_entry *ptr) | |
77 | { | |
78 | tomoyo_put_name(ptr->original_name); | |
79 | tomoyo_put_name(ptr->aliased_name); | |
80 | } | |
81 | ||
82 | static void tomoyo_del_manager(struct tomoyo_policy_manager_entry *ptr) | |
83 | { | |
84 | tomoyo_put_name(ptr->manager); | |
85 | } | |
86 | ||
87 | static void tomoyo_del_acl(struct tomoyo_acl_info *acl) | |
88 | { | |
89 | switch (acl->type) { | |
7ef61233 | 90 | case TOMOYO_TYPE_PATH_ACL: |
847b173e | 91 | { |
7ef61233 | 92 | struct tomoyo_path_acl *entry |
847b173e TH |
93 | = container_of(acl, typeof(*entry), head); |
94 | tomoyo_put_name(entry->filename); | |
95 | } | |
96 | break; | |
7ef61233 | 97 | case TOMOYO_TYPE_PATH2_ACL: |
847b173e | 98 | { |
7ef61233 | 99 | struct tomoyo_path2_acl *entry |
847b173e TH |
100 | = container_of(acl, typeof(*entry), head); |
101 | tomoyo_put_name(entry->filename1); | |
102 | tomoyo_put_name(entry->filename2); | |
103 | } | |
104 | break; | |
105 | default: | |
106 | printk(KERN_WARNING "Unknown type\n"); | |
107 | break; | |
108 | } | |
109 | } | |
110 | ||
111 | static bool tomoyo_del_domain(struct tomoyo_domain_info *domain) | |
112 | { | |
113 | struct tomoyo_acl_info *acl; | |
114 | struct tomoyo_acl_info *tmp; | |
115 | /* | |
116 | * Since we don't protect whole execve() operation using SRCU, | |
117 | * we need to recheck domain->users at this point. | |
118 | * | |
119 | * (1) Reader starts SRCU section upon execve(). | |
120 | * (2) Reader traverses tomoyo_domain_list and finds this domain. | |
121 | * (3) Writer marks this domain as deleted. | |
122 | * (4) Garbage collector removes this domain from tomoyo_domain_list | |
123 | * because this domain is marked as deleted and used by nobody. | |
124 | * (5) Reader saves reference to this domain into | |
125 | * "struct linux_binprm"->cred->security . | |
126 | * (6) Reader finishes SRCU section, although execve() operation has | |
127 | * not finished yet. | |
128 | * (7) Garbage collector waits for SRCU synchronization. | |
129 | * (8) Garbage collector kfree() this domain because this domain is | |
130 | * used by nobody. | |
131 | * (9) Reader finishes execve() operation and restores this domain from | |
132 | * "struct linux_binprm"->cred->security. | |
133 | * | |
134 | * By updating domain->users at (5), we can solve this race problem | |
135 | * by rechecking domain->users at (8). | |
136 | */ | |
137 | if (atomic_read(&domain->users)) | |
138 | return false; | |
139 | list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) { | |
140 | tomoyo_del_acl(acl); | |
141 | tomoyo_memory_free(acl); | |
142 | } | |
143 | tomoyo_put_name(domain->domainname); | |
144 | return true; | |
145 | } | |
146 | ||
147 | ||
148 | static void tomoyo_del_name(const struct tomoyo_name_entry *ptr) | |
149 | { | |
150 | } | |
151 | ||
152 | static void tomoyo_collect_entry(void) | |
153 | { | |
154 | mutex_lock(&tomoyo_policy_lock); | |
155 | { | |
156 | struct tomoyo_globally_readable_file_entry *ptr; | |
157 | list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list, | |
158 | list) { | |
159 | if (!ptr->is_deleted) | |
160 | continue; | |
161 | if (tomoyo_add_to_gc(TOMOYO_ID_GLOBALLY_READABLE, ptr)) | |
162 | list_del_rcu(&ptr->list); | |
163 | else | |
164 | break; | |
165 | } | |
166 | } | |
167 | { | |
168 | struct tomoyo_pattern_entry *ptr; | |
169 | list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) { | |
170 | if (!ptr->is_deleted) | |
171 | continue; | |
172 | if (tomoyo_add_to_gc(TOMOYO_ID_PATTERN, ptr)) | |
173 | list_del_rcu(&ptr->list); | |
174 | else | |
175 | break; | |
176 | } | |
177 | } | |
178 | { | |
179 | struct tomoyo_no_rewrite_entry *ptr; | |
180 | list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) { | |
181 | if (!ptr->is_deleted) | |
182 | continue; | |
183 | if (tomoyo_add_to_gc(TOMOYO_ID_NO_REWRITE, ptr)) | |
184 | list_del_rcu(&ptr->list); | |
185 | else | |
186 | break; | |
187 | } | |
188 | } | |
189 | { | |
190 | struct tomoyo_domain_initializer_entry *ptr; | |
191 | list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list, | |
192 | list) { | |
193 | if (!ptr->is_deleted) | |
194 | continue; | |
195 | if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_INITIALIZER, ptr)) | |
196 | list_del_rcu(&ptr->list); | |
197 | else | |
198 | break; | |
199 | } | |
200 | } | |
201 | { | |
202 | struct tomoyo_domain_keeper_entry *ptr; | |
203 | list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) { | |
204 | if (!ptr->is_deleted) | |
205 | continue; | |
206 | if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_KEEPER, ptr)) | |
207 | list_del_rcu(&ptr->list); | |
208 | else | |
209 | break; | |
210 | } | |
211 | } | |
212 | { | |
213 | struct tomoyo_alias_entry *ptr; | |
214 | list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) { | |
215 | if (!ptr->is_deleted) | |
216 | continue; | |
217 | if (tomoyo_add_to_gc(TOMOYO_ID_ALIAS, ptr)) | |
218 | list_del_rcu(&ptr->list); | |
219 | else | |
220 | break; | |
221 | } | |
222 | } | |
223 | { | |
224 | struct tomoyo_policy_manager_entry *ptr; | |
225 | list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list, | |
226 | list) { | |
227 | if (!ptr->is_deleted) | |
228 | continue; | |
229 | if (tomoyo_add_to_gc(TOMOYO_ID_MANAGER, ptr)) | |
230 | list_del_rcu(&ptr->list); | |
231 | else | |
232 | break; | |
233 | } | |
234 | } | |
235 | { | |
236 | struct tomoyo_domain_info *domain; | |
237 | list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) { | |
238 | struct tomoyo_acl_info *acl; | |
239 | list_for_each_entry_rcu(acl, &domain->acl_info_list, | |
240 | list) { | |
241 | switch (acl->type) { | |
7ef61233 | 242 | case TOMOYO_TYPE_PATH_ACL: |
847b173e | 243 | if (container_of(acl, |
7ef61233 | 244 | struct tomoyo_path_acl, |
847b173e TH |
245 | head)->perm || |
246 | container_of(acl, | |
7ef61233 | 247 | struct tomoyo_path_acl, |
847b173e TH |
248 | head)->perm_high) |
249 | continue; | |
250 | break; | |
7ef61233 | 251 | case TOMOYO_TYPE_PATH2_ACL: |
847b173e | 252 | if (container_of(acl, |
7ef61233 | 253 | struct tomoyo_path2_acl, |
847b173e TH |
254 | head)->perm) |
255 | continue; | |
256 | break; | |
257 | default: | |
258 | continue; | |
259 | } | |
260 | if (tomoyo_add_to_gc(TOMOYO_ID_ACL, acl)) | |
261 | list_del_rcu(&acl->list); | |
262 | else | |
263 | break; | |
264 | } | |
265 | if (!domain->is_deleted || atomic_read(&domain->users)) | |
266 | continue; | |
267 | /* | |
268 | * Nobody is referring this domain. But somebody may | |
269 | * refer this domain after successful execve(). | |
270 | * We recheck domain->users after SRCU synchronization. | |
271 | */ | |
272 | if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, domain)) | |
273 | list_del_rcu(&domain->list); | |
274 | else | |
275 | break; | |
276 | } | |
277 | } | |
278 | mutex_unlock(&tomoyo_policy_lock); | |
279 | mutex_lock(&tomoyo_name_list_lock); | |
280 | { | |
281 | int i; | |
282 | for (i = 0; i < TOMOYO_MAX_HASH; i++) { | |
283 | struct tomoyo_name_entry *ptr; | |
284 | list_for_each_entry_rcu(ptr, &tomoyo_name_list[i], | |
285 | list) { | |
286 | if (atomic_read(&ptr->users)) | |
287 | continue; | |
288 | if (tomoyo_add_to_gc(TOMOYO_ID_NAME, ptr)) | |
289 | list_del_rcu(&ptr->list); | |
290 | else { | |
291 | i = TOMOYO_MAX_HASH; | |
292 | break; | |
293 | } | |
294 | } | |
295 | } | |
296 | } | |
297 | mutex_unlock(&tomoyo_name_list_lock); | |
298 | } | |
299 | ||
300 | static void tomoyo_kfree_entry(void) | |
301 | { | |
302 | struct tomoyo_gc_entry *p; | |
303 | struct tomoyo_gc_entry *tmp; | |
304 | ||
305 | list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) { | |
306 | switch (p->type) { | |
307 | case TOMOYO_ID_DOMAIN_INITIALIZER: | |
308 | tomoyo_del_domain_initializer(p->element); | |
309 | break; | |
310 | case TOMOYO_ID_DOMAIN_KEEPER: | |
311 | tomoyo_del_domain_keeper(p->element); | |
312 | break; | |
313 | case TOMOYO_ID_ALIAS: | |
314 | tomoyo_del_alias(p->element); | |
315 | break; | |
316 | case TOMOYO_ID_GLOBALLY_READABLE: | |
317 | tomoyo_del_allow_read(p->element); | |
318 | break; | |
319 | case TOMOYO_ID_PATTERN: | |
320 | tomoyo_del_file_pattern(p->element); | |
321 | break; | |
322 | case TOMOYO_ID_NO_REWRITE: | |
323 | tomoyo_del_no_rewrite(p->element); | |
324 | break; | |
325 | case TOMOYO_ID_MANAGER: | |
326 | tomoyo_del_manager(p->element); | |
327 | break; | |
328 | case TOMOYO_ID_NAME: | |
329 | tomoyo_del_name(p->element); | |
330 | break; | |
331 | case TOMOYO_ID_ACL: | |
332 | tomoyo_del_acl(p->element); | |
333 | break; | |
334 | case TOMOYO_ID_DOMAIN: | |
335 | if (!tomoyo_del_domain(p->element)) | |
336 | continue; | |
337 | break; | |
338 | default: | |
339 | printk(KERN_WARNING "Unknown type\n"); | |
340 | break; | |
341 | } | |
342 | tomoyo_memory_free(p->element); | |
343 | list_del(&p->list); | |
344 | kfree(p); | |
345 | } | |
346 | } | |
347 | ||
348 | static int tomoyo_gc_thread(void *unused) | |
349 | { | |
350 | daemonize("GC for TOMOYO"); | |
351 | if (mutex_trylock(&tomoyo_gc_mutex)) { | |
352 | int i; | |
353 | for (i = 0; i < 10; i++) { | |
354 | tomoyo_collect_entry(); | |
355 | if (list_empty(&tomoyo_gc_queue)) | |
356 | break; | |
357 | synchronize_srcu(&tomoyo_ss); | |
358 | tomoyo_kfree_entry(); | |
359 | } | |
360 | mutex_unlock(&tomoyo_gc_mutex); | |
361 | } | |
362 | do_exit(0); | |
363 | } | |
364 | ||
365 | void tomoyo_run_gc(void) | |
366 | { | |
367 | struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL, | |
368 | "GC for TOMOYO"); | |
369 | if (!IS_ERR(task)) | |
370 | wake_up_process(task); | |
371 | } |