1 // SPDX-License-Identifier: GPL-2.0-or-later 1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Task credentials management - see Documenta 2 /* Task credentials management - see Documentation/security/credentials.rst
3 * 3 *
4 * Copyright (C) 2008 Red Hat, Inc. All Rights 4 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.c 5 * Written by David Howells (dhowells@redhat.com)
6 */ 6 */
7 <<
8 #define pr_fmt(fmt) "CRED: " fmt <<
9 <<
10 #include <linux/export.h> 7 #include <linux/export.h>
11 #include <linux/cred.h> 8 #include <linux/cred.h>
12 #include <linux/slab.h> 9 #include <linux/slab.h>
13 #include <linux/sched.h> 10 #include <linux/sched.h>
14 #include <linux/sched/coredump.h> 11 #include <linux/sched/coredump.h>
15 #include <linux/key.h> 12 #include <linux/key.h>
16 #include <linux/keyctl.h> 13 #include <linux/keyctl.h>
17 #include <linux/init_task.h> 14 #include <linux/init_task.h>
18 #include <linux/security.h> 15 #include <linux/security.h>
19 #include <linux/binfmts.h> 16 #include <linux/binfmts.h>
20 #include <linux/cn_proc.h> 17 #include <linux/cn_proc.h>
21 #include <linux/uidgid.h> 18 #include <linux/uidgid.h>
22 19
23 #if 0 20 #if 0
24 #define kdebug(FMT, ...) 21 #define kdebug(FMT, ...) \
25 printk("[%-5.5s%5u] " FMT "\n", 22 printk("[%-5.5s%5u] " FMT "\n", \
26 current->comm, current->pid, ## 23 current->comm, current->pid, ##__VA_ARGS__)
27 #else 24 #else
28 #define kdebug(FMT, ...) 25 #define kdebug(FMT, ...) \
29 do { 26 do { \
30 if (0) 27 if (0) \
31 no_printk("[%-5.5s%5u] " FMT " 28 no_printk("[%-5.5s%5u] " FMT "\n", \
32 current->comm, curre 29 current->comm, current->pid, ##__VA_ARGS__); \
33 } while (0) 30 } while (0)
34 #endif 31 #endif
35 32
36 static struct kmem_cache *cred_jar; 33 static struct kmem_cache *cred_jar;
37 34
38 /* init to 2 - one for init_task, one to ensur 35 /* init to 2 - one for init_task, one to ensure it is never freed */
39 static struct group_info init_groups = { .usag !! 36 static struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
40 37
41 /* 38 /*
42 * The initial credentials for the initial tas 39 * The initial credentials for the initial task
43 */ 40 */
44 struct cred init_cred = { 41 struct cred init_cred = {
45 .usage = ATOMIC_INIT( 42 .usage = ATOMIC_INIT(4),
>> 43 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 44 .subscribers = ATOMIC_INIT(2),
>> 45 .magic = CRED_MAGIC,
>> 46 #endif
46 .uid = GLOBAL_ROOT_ 47 .uid = GLOBAL_ROOT_UID,
47 .gid = GLOBAL_ROOT_ 48 .gid = GLOBAL_ROOT_GID,
48 .suid = GLOBAL_ROOT_ 49 .suid = GLOBAL_ROOT_UID,
49 .sgid = GLOBAL_ROOT_ 50 .sgid = GLOBAL_ROOT_GID,
50 .euid = GLOBAL_ROOT_ 51 .euid = GLOBAL_ROOT_UID,
51 .egid = GLOBAL_ROOT_ 52 .egid = GLOBAL_ROOT_GID,
52 .fsuid = GLOBAL_ROOT_ 53 .fsuid = GLOBAL_ROOT_UID,
53 .fsgid = GLOBAL_ROOT_ 54 .fsgid = GLOBAL_ROOT_GID,
54 .securebits = SECUREBITS_D 55 .securebits = SECUREBITS_DEFAULT,
55 .cap_inheritable = CAP_EMPTY_SE 56 .cap_inheritable = CAP_EMPTY_SET,
56 .cap_permitted = CAP_FULL_SET 57 .cap_permitted = CAP_FULL_SET,
57 .cap_effective = CAP_FULL_SET 58 .cap_effective = CAP_FULL_SET,
58 .cap_bset = CAP_FULL_SET 59 .cap_bset = CAP_FULL_SET,
59 .user = INIT_USER, 60 .user = INIT_USER,
60 .user_ns = &init_user_n 61 .user_ns = &init_user_ns,
61 .group_info = &init_groups 62 .group_info = &init_groups,
62 .ucounts = &init_ucount 63 .ucounts = &init_ucounts,
63 }; 64 };
64 65
>> 66 static inline void set_cred_subscribers(struct cred *cred, int n)
>> 67 {
>> 68 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 69 atomic_set(&cred->subscribers, n);
>> 70 #endif
>> 71 }
>> 72
>> 73 static inline int read_cred_subscribers(const struct cred *cred)
>> 74 {
>> 75 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 76 return atomic_read(&cred->subscribers);
>> 77 #else
>> 78 return 0;
>> 79 #endif
>> 80 }
>> 81
>> 82 static inline void alter_cred_subscribers(const struct cred *_cred, int n)
>> 83 {
>> 84 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 85 struct cred *cred = (struct cred *) _cred;
>> 86
>> 87 atomic_add(n, &cred->subscribers);
>> 88 #endif
>> 89 }
>> 90
65 /* 91 /*
66 * The RCU callback to actually dispose of a s 92 * The RCU callback to actually dispose of a set of credentials
67 */ 93 */
68 static void put_cred_rcu(struct rcu_head *rcu) 94 static void put_cred_rcu(struct rcu_head *rcu)
69 { 95 {
70 struct cred *cred = container_of(rcu, 96 struct cred *cred = container_of(rcu, struct cred, rcu);
71 97
72 kdebug("put_cred_rcu(%p)", cred); 98 kdebug("put_cred_rcu(%p)", cred);
73 99
74 if (atomic_long_read(&cred->usage) != !! 100 #ifdef CONFIG_DEBUG_CREDENTIALS
75 panic("CRED: put_cred_rcu() se !! 101 if (cred->magic != CRED_MAGIC_DEAD ||
76 cred, atomic_long_read(& !! 102 atomic_read(&cred->usage) != 0 ||
>> 103 read_cred_subscribers(cred) != 0)
>> 104 panic("CRED: put_cred_rcu() sees %p with"
>> 105 " mag %x, put %p, usage %d, subscr %d\n",
>> 106 cred, cred->magic, cred->put_addr,
>> 107 atomic_read(&cred->usage),
>> 108 read_cred_subscribers(cred));
>> 109 #else
>> 110 if (atomic_read(&cred->usage) != 0)
>> 111 panic("CRED: put_cred_rcu() sees %p with usage %d\n",
>> 112 cred, atomic_read(&cred->usage));
>> 113 #endif
77 114
78 security_cred_free(cred); 115 security_cred_free(cred);
79 key_put(cred->session_keyring); 116 key_put(cred->session_keyring);
80 key_put(cred->process_keyring); 117 key_put(cred->process_keyring);
81 key_put(cred->thread_keyring); 118 key_put(cred->thread_keyring);
82 key_put(cred->request_key_auth); 119 key_put(cred->request_key_auth);
83 if (cred->group_info) 120 if (cred->group_info)
84 put_group_info(cred->group_inf 121 put_group_info(cred->group_info);
85 free_uid(cred->user); 122 free_uid(cred->user);
86 if (cred->ucounts) 123 if (cred->ucounts)
87 put_ucounts(cred->ucounts); 124 put_ucounts(cred->ucounts);
88 put_user_ns(cred->user_ns); 125 put_user_ns(cred->user_ns);
89 kmem_cache_free(cred_jar, cred); 126 kmem_cache_free(cred_jar, cred);
90 } 127 }
91 128
92 /** 129 /**
93 * __put_cred - Destroy a set of credentials 130 * __put_cred - Destroy a set of credentials
94 * @cred: The record to release 131 * @cred: The record to release
95 * 132 *
96 * Destroy a set of credentials on which no re 133 * Destroy a set of credentials on which no references remain.
97 */ 134 */
98 void __put_cred(struct cred *cred) 135 void __put_cred(struct cred *cred)
99 { 136 {
100 kdebug("__put_cred(%p{%ld})", cred, !! 137 kdebug("__put_cred(%p{%d,%d})", cred,
101 atomic_long_read(&cred->usage)) !! 138 atomic_read(&cred->usage),
102 !! 139 read_cred_subscribers(cred));
103 BUG_ON(atomic_long_read(&cred->usage) !! 140
>> 141 BUG_ON(atomic_read(&cred->usage) != 0);
>> 142 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 143 BUG_ON(read_cred_subscribers(cred) != 0);
>> 144 cred->magic = CRED_MAGIC_DEAD;
>> 145 cred->put_addr = __builtin_return_address(0);
>> 146 #endif
104 BUG_ON(cred == current->cred); 147 BUG_ON(cred == current->cred);
105 BUG_ON(cred == current->real_cred); 148 BUG_ON(cred == current->real_cred);
106 149
107 if (cred->non_rcu) 150 if (cred->non_rcu)
108 put_cred_rcu(&cred->rcu); 151 put_cred_rcu(&cred->rcu);
109 else 152 else
110 call_rcu(&cred->rcu, put_cred_ 153 call_rcu(&cred->rcu, put_cred_rcu);
111 } 154 }
112 EXPORT_SYMBOL(__put_cred); 155 EXPORT_SYMBOL(__put_cred);
113 156
114 /* 157 /*
115 * Clean up a task's credentials when it exits 158 * Clean up a task's credentials when it exits
116 */ 159 */
117 void exit_creds(struct task_struct *tsk) 160 void exit_creds(struct task_struct *tsk)
118 { 161 {
119 struct cred *real_cred, *cred; !! 162 struct cred *cred;
120 163
121 kdebug("exit_creds(%u,%p,%p,{%ld})", t !! 164 kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
122 atomic_long_read(&tsk->cred->us !! 165 atomic_read(&tsk->cred->usage),
>> 166 read_cred_subscribers(tsk->cred));
123 167
124 real_cred = (struct cred *) tsk->real_ !! 168 cred = (struct cred *) tsk->real_cred;
125 tsk->real_cred = NULL; 169 tsk->real_cred = NULL;
>> 170 validate_creds(cred);
>> 171 alter_cred_subscribers(cred, -1);
>> 172 put_cred(cred);
126 173
127 cred = (struct cred *) tsk->cred; 174 cred = (struct cred *) tsk->cred;
128 tsk->cred = NULL; 175 tsk->cred = NULL;
129 !! 176 validate_creds(cred);
130 if (real_cred == cred) { !! 177 alter_cred_subscribers(cred, -1);
131 put_cred_many(cred, 2); !! 178 put_cred(cred);
132 } else { <<
133 put_cred(real_cred); <<
134 put_cred(cred); <<
135 } <<
136 179
137 #ifdef CONFIG_KEYS_REQUEST_CACHE 180 #ifdef CONFIG_KEYS_REQUEST_CACHE
138 key_put(tsk->cached_requested_key); 181 key_put(tsk->cached_requested_key);
139 tsk->cached_requested_key = NULL; 182 tsk->cached_requested_key = NULL;
140 #endif 183 #endif
141 } 184 }
142 185
143 /** 186 /**
144 * get_task_cred - Get another task's objectiv 187 * get_task_cred - Get another task's objective credentials
145 * @task: The task to query 188 * @task: The task to query
146 * 189 *
147 * Get the objective credentials of a task, pi 190 * Get the objective credentials of a task, pinning them so that they can't go
148 * away. Accessing a task's credentials direc 191 * away. Accessing a task's credentials directly is not permitted.
149 * 192 *
150 * The caller must also make sure task doesn't 193 * The caller must also make sure task doesn't get deleted, either by holding a
151 * ref on task or by holding tasklist_lock to 194 * ref on task or by holding tasklist_lock to prevent it from being unlinked.
152 */ 195 */
153 const struct cred *get_task_cred(struct task_s 196 const struct cred *get_task_cred(struct task_struct *task)
154 { 197 {
155 const struct cred *cred; 198 const struct cred *cred;
156 199
157 rcu_read_lock(); 200 rcu_read_lock();
158 201
159 do { 202 do {
160 cred = __task_cred((task)); 203 cred = __task_cred((task));
161 BUG_ON(!cred); 204 BUG_ON(!cred);
162 } while (!get_cred_rcu(cred)); 205 } while (!get_cred_rcu(cred));
163 206
164 rcu_read_unlock(); 207 rcu_read_unlock();
165 return cred; 208 return cred;
166 } 209 }
167 EXPORT_SYMBOL(get_task_cred); 210 EXPORT_SYMBOL(get_task_cred);
168 211
169 /* 212 /*
170 * Allocate blank credentials, such that the c 213 * Allocate blank credentials, such that the credentials can be filled in at a
171 * later date without risk of ENOMEM. 214 * later date without risk of ENOMEM.
172 */ 215 */
173 struct cred *cred_alloc_blank(void) 216 struct cred *cred_alloc_blank(void)
174 { 217 {
175 struct cred *new; 218 struct cred *new;
176 219
177 new = kmem_cache_zalloc(cred_jar, GFP_ 220 new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
178 if (!new) 221 if (!new)
179 return NULL; 222 return NULL;
180 223
181 atomic_long_set(&new->usage, 1); !! 224 atomic_set(&new->usage, 1);
>> 225 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 226 new->magic = CRED_MAGIC;
>> 227 #endif
182 if (security_cred_alloc_blank(new, GFP 228 if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
183 goto error; 229 goto error;
184 230
185 return new; 231 return new;
186 232
187 error: 233 error:
188 abort_creds(new); 234 abort_creds(new);
189 return NULL; 235 return NULL;
190 } 236 }
191 237
192 /** 238 /**
193 * prepare_creds - Prepare a new set of creden 239 * prepare_creds - Prepare a new set of credentials for modification
194 * 240 *
195 * Prepare a new set of task credentials for m 241 * Prepare a new set of task credentials for modification. A task's creds
196 * shouldn't generally be modified directly, t 242 * shouldn't generally be modified directly, therefore this function is used to
197 * prepare a new copy, which the caller then m 243 * prepare a new copy, which the caller then modifies and then commits by
198 * calling commit_creds(). 244 * calling commit_creds().
199 * 245 *
200 * Preparation involves making a copy of the o 246 * Preparation involves making a copy of the objective creds for modification.
201 * 247 *
202 * Returns a pointer to the new creds-to-be if 248 * Returns a pointer to the new creds-to-be if successful, NULL otherwise.
203 * 249 *
204 * Call commit_creds() or abort_creds() to cle 250 * Call commit_creds() or abort_creds() to clean up.
205 */ 251 */
206 struct cred *prepare_creds(void) 252 struct cred *prepare_creds(void)
207 { 253 {
208 struct task_struct *task = current; 254 struct task_struct *task = current;
209 const struct cred *old; 255 const struct cred *old;
210 struct cred *new; 256 struct cred *new;
211 257
>> 258 validate_process_creds();
>> 259
212 new = kmem_cache_alloc(cred_jar, GFP_K 260 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
213 if (!new) 261 if (!new)
214 return NULL; 262 return NULL;
215 263
216 kdebug("prepare_creds() alloc %p", new 264 kdebug("prepare_creds() alloc %p", new);
217 265
218 old = task->cred; 266 old = task->cred;
219 memcpy(new, old, sizeof(struct cred)); 267 memcpy(new, old, sizeof(struct cred));
220 268
221 new->non_rcu = 0; 269 new->non_rcu = 0;
222 atomic_long_set(&new->usage, 1); !! 270 atomic_set(&new->usage, 1);
>> 271 set_cred_subscribers(new, 0);
223 get_group_info(new->group_info); 272 get_group_info(new->group_info);
224 get_uid(new->user); 273 get_uid(new->user);
225 get_user_ns(new->user_ns); 274 get_user_ns(new->user_ns);
226 275
227 #ifdef CONFIG_KEYS 276 #ifdef CONFIG_KEYS
228 key_get(new->session_keyring); 277 key_get(new->session_keyring);
229 key_get(new->process_keyring); 278 key_get(new->process_keyring);
230 key_get(new->thread_keyring); 279 key_get(new->thread_keyring);
231 key_get(new->request_key_auth); 280 key_get(new->request_key_auth);
232 #endif 281 #endif
233 282
234 #ifdef CONFIG_SECURITY 283 #ifdef CONFIG_SECURITY
235 new->security = NULL; 284 new->security = NULL;
236 #endif 285 #endif
237 286
238 new->ucounts = get_ucounts(new->ucount 287 new->ucounts = get_ucounts(new->ucounts);
239 if (!new->ucounts) 288 if (!new->ucounts)
240 goto error; 289 goto error;
241 290
242 if (security_prepare_creds(new, old, G 291 if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
243 goto error; 292 goto error;
244 293
>> 294 validate_creds(new);
245 return new; 295 return new;
246 296
247 error: 297 error:
248 abort_creds(new); 298 abort_creds(new);
249 return NULL; 299 return NULL;
250 } 300 }
251 EXPORT_SYMBOL(prepare_creds); 301 EXPORT_SYMBOL(prepare_creds);
252 302
253 /* 303 /*
254 * Prepare credentials for current to perform 304 * Prepare credentials for current to perform an execve()
255 * - The caller must hold ->cred_guard_mutex 305 * - The caller must hold ->cred_guard_mutex
256 */ 306 */
257 struct cred *prepare_exec_creds(void) 307 struct cred *prepare_exec_creds(void)
258 { 308 {
259 struct cred *new; 309 struct cred *new;
260 310
261 new = prepare_creds(); 311 new = prepare_creds();
262 if (!new) 312 if (!new)
263 return new; 313 return new;
264 314
265 #ifdef CONFIG_KEYS 315 #ifdef CONFIG_KEYS
266 /* newly exec'd tasks don't get a thre 316 /* newly exec'd tasks don't get a thread keyring */
267 key_put(new->thread_keyring); 317 key_put(new->thread_keyring);
268 new->thread_keyring = NULL; 318 new->thread_keyring = NULL;
269 319
270 /* inherit the session keyring; new pr 320 /* inherit the session keyring; new process keyring */
271 key_put(new->process_keyring); 321 key_put(new->process_keyring);
272 new->process_keyring = NULL; 322 new->process_keyring = NULL;
273 #endif 323 #endif
274 324
275 new->suid = new->fsuid = new->euid; 325 new->suid = new->fsuid = new->euid;
276 new->sgid = new->fsgid = new->egid; 326 new->sgid = new->fsgid = new->egid;
277 327
278 return new; 328 return new;
279 } 329 }
280 330
281 /* 331 /*
282 * Copy credentials for the new process create 332 * Copy credentials for the new process created by fork()
283 * 333 *
284 * We share if we can, but under some circumst 334 * We share if we can, but under some circumstances we have to generate a new
285 * set. 335 * set.
286 * 336 *
287 * The new process gets the current process's 337 * The new process gets the current process's subjective credentials as its
288 * objective and subjective credentials 338 * objective and subjective credentials
289 */ 339 */
290 int copy_creds(struct task_struct *p, unsigned 340 int copy_creds(struct task_struct *p, unsigned long clone_flags)
291 { 341 {
292 struct cred *new; 342 struct cred *new;
293 int ret; 343 int ret;
294 344
295 #ifdef CONFIG_KEYS_REQUEST_CACHE 345 #ifdef CONFIG_KEYS_REQUEST_CACHE
296 p->cached_requested_key = NULL; 346 p->cached_requested_key = NULL;
297 #endif 347 #endif
298 348
299 if ( 349 if (
300 #ifdef CONFIG_KEYS 350 #ifdef CONFIG_KEYS
301 !p->cred->thread_keyring && 351 !p->cred->thread_keyring &&
302 #endif 352 #endif
303 clone_flags & CLONE_THREAD 353 clone_flags & CLONE_THREAD
304 ) { 354 ) {
305 p->real_cred = get_cred_many(p !! 355 p->real_cred = get_cred(p->cred);
306 kdebug("share_creds(%p{%ld})", !! 356 get_cred(p->cred);
307 p->cred, atomic_long_re !! 357 alter_cred_subscribers(p->cred, 2);
>> 358 kdebug("share_creds(%p{%d,%d})",
>> 359 p->cred, atomic_read(&p->cred->usage),
>> 360 read_cred_subscribers(p->cred));
308 inc_rlimit_ucounts(task_ucount 361 inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
309 return 0; 362 return 0;
310 } 363 }
311 364
312 new = prepare_creds(); 365 new = prepare_creds();
313 if (!new) 366 if (!new)
314 return -ENOMEM; 367 return -ENOMEM;
315 368
316 if (clone_flags & CLONE_NEWUSER) { 369 if (clone_flags & CLONE_NEWUSER) {
317 ret = create_user_ns(new); 370 ret = create_user_ns(new);
318 if (ret < 0) 371 if (ret < 0)
319 goto error_put; 372 goto error_put;
320 ret = set_cred_ucounts(new); 373 ret = set_cred_ucounts(new);
321 if (ret < 0) 374 if (ret < 0)
322 goto error_put; 375 goto error_put;
323 } 376 }
324 377
325 #ifdef CONFIG_KEYS 378 #ifdef CONFIG_KEYS
326 /* new threads get their own thread ke 379 /* new threads get their own thread keyrings if their parent already
327 * had one */ 380 * had one */
328 if (new->thread_keyring) { 381 if (new->thread_keyring) {
329 key_put(new->thread_keyring); 382 key_put(new->thread_keyring);
330 new->thread_keyring = NULL; 383 new->thread_keyring = NULL;
331 if (clone_flags & CLONE_THREAD 384 if (clone_flags & CLONE_THREAD)
332 install_thread_keyring 385 install_thread_keyring_to_cred(new);
333 } 386 }
334 387
335 /* The process keyring is only shared 388 /* The process keyring is only shared between the threads in a process;
336 * anything outside of those threads d 389 * anything outside of those threads doesn't inherit.
337 */ 390 */
338 if (!(clone_flags & CLONE_THREAD)) { 391 if (!(clone_flags & CLONE_THREAD)) {
339 key_put(new->process_keyring); 392 key_put(new->process_keyring);
340 new->process_keyring = NULL; 393 new->process_keyring = NULL;
341 } 394 }
342 #endif 395 #endif
343 396
344 p->cred = p->real_cred = get_cred(new) 397 p->cred = p->real_cred = get_cred(new);
345 inc_rlimit_ucounts(task_ucounts(p), UC 398 inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
>> 399 alter_cred_subscribers(new, 2);
>> 400 validate_creds(new);
346 return 0; 401 return 0;
347 402
348 error_put: 403 error_put:
349 put_cred(new); 404 put_cred(new);
350 return ret; 405 return ret;
351 } 406 }
352 407
353 static bool cred_cap_issubset(const struct cre 408 static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
354 { 409 {
355 const struct user_namespace *set_ns = 410 const struct user_namespace *set_ns = set->user_ns;
356 const struct user_namespace *subset_ns 411 const struct user_namespace *subset_ns = subset->user_ns;
357 412
358 /* If the two credentials are in the s 413 /* If the two credentials are in the same user namespace see if
359 * the capabilities of subset are a su 414 * the capabilities of subset are a subset of set.
360 */ 415 */
361 if (set_ns == subset_ns) 416 if (set_ns == subset_ns)
362 return cap_issubset(subset->ca 417 return cap_issubset(subset->cap_permitted, set->cap_permitted);
363 418
364 /* The credentials are in a different 419 /* The credentials are in a different user namespaces
365 * therefore one is a subset of the ot 420 * therefore one is a subset of the other only if a set is an
366 * ancestor of subset and set->euid is 421 * ancestor of subset and set->euid is owner of subset or one
367 * of subsets ancestors. 422 * of subsets ancestors.
368 */ 423 */
369 for (;subset_ns != &init_user_ns; subs 424 for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
370 if ((set_ns == subset_ns->pare 425 if ((set_ns == subset_ns->parent) &&
371 uid_eq(subset_ns->owner, s 426 uid_eq(subset_ns->owner, set->euid))
372 return true; 427 return true;
373 } 428 }
374 429
375 return false; 430 return false;
376 } 431 }
377 432
378 /** 433 /**
379 * commit_creds - Install new credentials upon 434 * commit_creds - Install new credentials upon the current task
380 * @new: The credentials to be assigned 435 * @new: The credentials to be assigned
381 * 436 *
382 * Install a new set of credentials to the cur 437 * Install a new set of credentials to the current task, using RCU to replace
383 * the old set. Both the objective and the su 438 * the old set. Both the objective and the subjective credentials pointers are
384 * updated. This function may not be called i 439 * updated. This function may not be called if the subjective credentials are
385 * in an overridden state. 440 * in an overridden state.
386 * 441 *
387 * This function eats the caller's reference t 442 * This function eats the caller's reference to the new credentials.
388 * 443 *
389 * Always returns 0 thus allowing this functio 444 * Always returns 0 thus allowing this function to be tail-called at the end
390 * of, say, sys_setgid(). 445 * of, say, sys_setgid().
391 */ 446 */
392 int commit_creds(struct cred *new) 447 int commit_creds(struct cred *new)
393 { 448 {
394 struct task_struct *task = current; 449 struct task_struct *task = current;
395 const struct cred *old = task->real_cr 450 const struct cred *old = task->real_cred;
396 451
397 kdebug("commit_creds(%p{%ld})", new, !! 452 kdebug("commit_creds(%p{%d,%d})", new,
398 atomic_long_read(&new->usage)); !! 453 atomic_read(&new->usage),
>> 454 read_cred_subscribers(new));
399 455
400 BUG_ON(task->cred != old); 456 BUG_ON(task->cred != old);
401 BUG_ON(atomic_long_read(&new->usage) < !! 457 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 458 BUG_ON(read_cred_subscribers(old) < 2);
>> 459 validate_creds(old);
>> 460 validate_creds(new);
>> 461 #endif
>> 462 BUG_ON(atomic_read(&new->usage) < 1);
402 463
403 get_cred(new); /* we will require a re 464 get_cred(new); /* we will require a ref for the subj creds too */
404 465
405 /* dumpability changes */ 466 /* dumpability changes */
406 if (!uid_eq(old->euid, new->euid) || 467 if (!uid_eq(old->euid, new->euid) ||
407 !gid_eq(old->egid, new->egid) || 468 !gid_eq(old->egid, new->egid) ||
408 !uid_eq(old->fsuid, new->fsuid) || 469 !uid_eq(old->fsuid, new->fsuid) ||
409 !gid_eq(old->fsgid, new->fsgid) || 470 !gid_eq(old->fsgid, new->fsgid) ||
410 !cred_cap_issubset(old, new)) { 471 !cred_cap_issubset(old, new)) {
411 if (task->mm) 472 if (task->mm)
412 set_dumpable(task->mm, 473 set_dumpable(task->mm, suid_dumpable);
413 task->pdeath_signal = 0; 474 task->pdeath_signal = 0;
414 /* 475 /*
415 * If a task drops privileges 476 * If a task drops privileges and becomes nondumpable,
416 * the dumpability change must 477 * the dumpability change must become visible before
417 * the credential change; othe 478 * the credential change; otherwise, a __ptrace_may_access()
418 * racing with this change may 479 * racing with this change may be able to attach to a task it
419 * shouldn't be able to attach 480 * shouldn't be able to attach to (as if the task had dropped
420 * privileges without becoming 481 * privileges without becoming nondumpable).
421 * Pairs with a read barrier i 482 * Pairs with a read barrier in __ptrace_may_access().
422 */ 483 */
423 smp_wmb(); 484 smp_wmb();
424 } 485 }
425 486
426 /* alter the thread keyring */ 487 /* alter the thread keyring */
427 if (!uid_eq(new->fsuid, old->fsuid)) 488 if (!uid_eq(new->fsuid, old->fsuid))
428 key_fsuid_changed(new); 489 key_fsuid_changed(new);
429 if (!gid_eq(new->fsgid, old->fsgid)) 490 if (!gid_eq(new->fsgid, old->fsgid))
430 key_fsgid_changed(new); 491 key_fsgid_changed(new);
431 492
432 /* do it 493 /* do it
433 * RLIMIT_NPROC limits on user->proces 494 * RLIMIT_NPROC limits on user->processes have already been checked
434 * in set_user(). 495 * in set_user().
435 */ 496 */
>> 497 alter_cred_subscribers(new, 2);
436 if (new->user != old->user || new->use 498 if (new->user != old->user || new->user_ns != old->user_ns)
437 inc_rlimit_ucounts(new->ucount 499 inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
438 rcu_assign_pointer(task->real_cred, ne 500 rcu_assign_pointer(task->real_cred, new);
439 rcu_assign_pointer(task->cred, new); 501 rcu_assign_pointer(task->cred, new);
440 if (new->user != old->user || new->use 502 if (new->user != old->user || new->user_ns != old->user_ns)
441 dec_rlimit_ucounts(old->ucount 503 dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
>> 504 alter_cred_subscribers(old, -2);
442 505
443 /* send notifications */ 506 /* send notifications */
444 if (!uid_eq(new->uid, old->uid) || 507 if (!uid_eq(new->uid, old->uid) ||
445 !uid_eq(new->euid, old->euid) || 508 !uid_eq(new->euid, old->euid) ||
446 !uid_eq(new->suid, old->suid) || 509 !uid_eq(new->suid, old->suid) ||
447 !uid_eq(new->fsuid, old->fsuid)) 510 !uid_eq(new->fsuid, old->fsuid))
448 proc_id_connector(task, PROC_E 511 proc_id_connector(task, PROC_EVENT_UID);
449 512
450 if (!gid_eq(new->gid, old->gid) || 513 if (!gid_eq(new->gid, old->gid) ||
451 !gid_eq(new->egid, old->egid) || 514 !gid_eq(new->egid, old->egid) ||
452 !gid_eq(new->sgid, old->sgid) || 515 !gid_eq(new->sgid, old->sgid) ||
453 !gid_eq(new->fsgid, old->fsgid)) 516 !gid_eq(new->fsgid, old->fsgid))
454 proc_id_connector(task, PROC_E 517 proc_id_connector(task, PROC_EVENT_GID);
455 518
456 /* release the old obj and subj refs b 519 /* release the old obj and subj refs both */
457 put_cred_many(old, 2); !! 520 put_cred(old);
>> 521 put_cred(old);
458 return 0; 522 return 0;
459 } 523 }
460 EXPORT_SYMBOL(commit_creds); 524 EXPORT_SYMBOL(commit_creds);
461 525
462 /** 526 /**
463 * abort_creds - Discard a set of credentials 527 * abort_creds - Discard a set of credentials and unlock the current task
464 * @new: The credentials that were going to be 528 * @new: The credentials that were going to be applied
465 * 529 *
466 * Discard a set of credentials that were unde 530 * Discard a set of credentials that were under construction and unlock the
467 * current task. 531 * current task.
468 */ 532 */
469 void abort_creds(struct cred *new) 533 void abort_creds(struct cred *new)
470 { 534 {
471 kdebug("abort_creds(%p{%ld})", new, !! 535 kdebug("abort_creds(%p{%d,%d})", new,
472 atomic_long_read(&new->usage)); !! 536 atomic_read(&new->usage),
>> 537 read_cred_subscribers(new));
473 538
474 BUG_ON(atomic_long_read(&new->usage) < !! 539 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 540 BUG_ON(read_cred_subscribers(new) != 0);
>> 541 #endif
>> 542 BUG_ON(atomic_read(&new->usage) < 1);
475 put_cred(new); 543 put_cred(new);
476 } 544 }
477 EXPORT_SYMBOL(abort_creds); 545 EXPORT_SYMBOL(abort_creds);
478 546
479 /** 547 /**
480 * override_creds - Override the current proce 548 * override_creds - Override the current process's subjective credentials
481 * @new: The credentials to be assigned 549 * @new: The credentials to be assigned
482 * 550 *
483 * Install a set of temporary override subject 551 * Install a set of temporary override subjective credentials on the current
484 * process, returning the old set for later re 552 * process, returning the old set for later reversion.
485 */ 553 */
486 const struct cred *override_creds(const struct 554 const struct cred *override_creds(const struct cred *new)
487 { 555 {
488 const struct cred *old = current->cred 556 const struct cred *old = current->cred;
489 557
490 kdebug("override_creds(%p{%ld})", new, !! 558 kdebug("override_creds(%p{%d,%d})", new,
491 atomic_long_read(&new->usage)); !! 559 atomic_read(&new->usage),
>> 560 read_cred_subscribers(new));
>> 561
>> 562 validate_creds(old);
>> 563 validate_creds(new);
492 564
493 /* 565 /*
494 * NOTE! This uses 'get_new_cred()' ra 566 * NOTE! This uses 'get_new_cred()' rather than 'get_cred()'.
495 * 567 *
496 * That means that we do not clear the 568 * That means that we do not clear the 'non_rcu' flag, since
497 * we are only installing the cred int 569 * we are only installing the cred into the thread-synchronous
498 * '->cred' pointer, not the '->real_c 570 * '->cred' pointer, not the '->real_cred' pointer that is
499 * visible to other threads under RCU. 571 * visible to other threads under RCU.
>> 572 *
>> 573 * Also note that we did validate_creds() manually, not depending
>> 574 * on the validation in 'get_cred()'.
500 */ 575 */
501 get_new_cred((struct cred *)new); 576 get_new_cred((struct cred *)new);
>> 577 alter_cred_subscribers(new, 1);
502 rcu_assign_pointer(current->cred, new) 578 rcu_assign_pointer(current->cred, new);
>> 579 alter_cred_subscribers(old, -1);
503 580
504 kdebug("override_creds() = %p{%ld}", o !! 581 kdebug("override_creds() = %p{%d,%d}", old,
505 atomic_long_read(&old->usage)); !! 582 atomic_read(&old->usage),
>> 583 read_cred_subscribers(old));
506 return old; 584 return old;
507 } 585 }
508 EXPORT_SYMBOL(override_creds); 586 EXPORT_SYMBOL(override_creds);
509 587
510 /** 588 /**
511 * revert_creds - Revert a temporary subjectiv 589 * revert_creds - Revert a temporary subjective credentials override
512 * @old: The credentials to be restored 590 * @old: The credentials to be restored
513 * 591 *
514 * Revert a temporary set of override subjecti 592 * Revert a temporary set of override subjective credentials to an old set,
515 * discarding the override set. 593 * discarding the override set.
516 */ 594 */
517 void revert_creds(const struct cred *old) 595 void revert_creds(const struct cred *old)
518 { 596 {
519 const struct cred *override = current- 597 const struct cred *override = current->cred;
520 598
521 kdebug("revert_creds(%p{%ld})", old, !! 599 kdebug("revert_creds(%p{%d,%d})", old,
522 atomic_long_read(&old->usage)); !! 600 atomic_read(&old->usage),
523 !! 601 read_cred_subscribers(old));
>> 602
>> 603 validate_creds(old);
>> 604 validate_creds(override);
>> 605 alter_cred_subscribers(old, 1);
524 rcu_assign_pointer(current->cred, old) 606 rcu_assign_pointer(current->cred, old);
>> 607 alter_cred_subscribers(override, -1);
525 put_cred(override); 608 put_cred(override);
526 } 609 }
527 EXPORT_SYMBOL(revert_creds); 610 EXPORT_SYMBOL(revert_creds);
528 611
529 /** 612 /**
530 * cred_fscmp - Compare two credentials with r 613 * cred_fscmp - Compare two credentials with respect to filesystem access.
531 * @a: The first credential 614 * @a: The first credential
532 * @b: The second credential 615 * @b: The second credential
533 * 616 *
534 * cred_cmp() will return zero if both credent 617 * cred_cmp() will return zero if both credentials have the same
535 * fsuid, fsgid, and supplementary groups. Th 618 * fsuid, fsgid, and supplementary groups. That is, if they will both
536 * provide the same access to files based on m 619 * provide the same access to files based on mode/uid/gid.
537 * If the credentials are different, then eith 620 * If the credentials are different, then either -1 or 1 will
538 * be returned depending on whether @a comes b 621 * be returned depending on whether @a comes before or after @b
539 * respectively in an arbitrary, but stable, o 622 * respectively in an arbitrary, but stable, ordering of credentials.
540 * 623 *
541 * Return: -1, 0, or 1 depending on comparison 624 * Return: -1, 0, or 1 depending on comparison
542 */ 625 */
543 int cred_fscmp(const struct cred *a, const str 626 int cred_fscmp(const struct cred *a, const struct cred *b)
544 { 627 {
545 struct group_info *ga, *gb; 628 struct group_info *ga, *gb;
546 int g; 629 int g;
547 630
548 if (a == b) 631 if (a == b)
549 return 0; 632 return 0;
550 if (uid_lt(a->fsuid, b->fsuid)) 633 if (uid_lt(a->fsuid, b->fsuid))
551 return -1; 634 return -1;
552 if (uid_gt(a->fsuid, b->fsuid)) 635 if (uid_gt(a->fsuid, b->fsuid))
553 return 1; 636 return 1;
554 637
555 if (gid_lt(a->fsgid, b->fsgid)) 638 if (gid_lt(a->fsgid, b->fsgid))
556 return -1; 639 return -1;
557 if (gid_gt(a->fsgid, b->fsgid)) 640 if (gid_gt(a->fsgid, b->fsgid))
558 return 1; 641 return 1;
559 642
560 ga = a->group_info; 643 ga = a->group_info;
561 gb = b->group_info; 644 gb = b->group_info;
562 if (ga == gb) 645 if (ga == gb)
563 return 0; 646 return 0;
564 if (ga == NULL) 647 if (ga == NULL)
565 return -1; 648 return -1;
566 if (gb == NULL) 649 if (gb == NULL)
567 return 1; 650 return 1;
568 if (ga->ngroups < gb->ngroups) 651 if (ga->ngroups < gb->ngroups)
569 return -1; 652 return -1;
570 if (ga->ngroups > gb->ngroups) 653 if (ga->ngroups > gb->ngroups)
571 return 1; 654 return 1;
572 655
573 for (g = 0; g < ga->ngroups; g++) { 656 for (g = 0; g < ga->ngroups; g++) {
574 if (gid_lt(ga->gid[g], gb->gid 657 if (gid_lt(ga->gid[g], gb->gid[g]))
575 return -1; 658 return -1;
576 if (gid_gt(ga->gid[g], gb->gid 659 if (gid_gt(ga->gid[g], gb->gid[g]))
577 return 1; 660 return 1;
578 } 661 }
579 return 0; 662 return 0;
580 } 663 }
581 EXPORT_SYMBOL(cred_fscmp); 664 EXPORT_SYMBOL(cred_fscmp);
582 665
583 int set_cred_ucounts(struct cred *new) 666 int set_cred_ucounts(struct cred *new)
584 { 667 {
585 struct ucounts *new_ucounts, *old_ucou 668 struct ucounts *new_ucounts, *old_ucounts = new->ucounts;
586 669
587 /* 670 /*
588 * This optimization is needed because 671 * This optimization is needed because alloc_ucounts() uses locks
589 * for table lookups. 672 * for table lookups.
590 */ 673 */
591 if (old_ucounts->ns == new->user_ns && 674 if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->uid))
592 return 0; 675 return 0;
593 676
594 if (!(new_ucounts = alloc_ucounts(new- 677 if (!(new_ucounts = alloc_ucounts(new->user_ns, new->uid)))
595 return -EAGAIN; 678 return -EAGAIN;
596 679
597 new->ucounts = new_ucounts; 680 new->ucounts = new_ucounts;
598 put_ucounts(old_ucounts); 681 put_ucounts(old_ucounts);
599 682
600 return 0; 683 return 0;
601 } 684 }
602 685
603 /* 686 /*
604 * initialise the credentials stuff 687 * initialise the credentials stuff
605 */ 688 */
606 void __init cred_init(void) 689 void __init cred_init(void)
607 { 690 {
608 /* allocate a slab in which we can sto 691 /* allocate a slab in which we can store credentials */
609 cred_jar = KMEM_CACHE(cred, !! 692 cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
610 SLAB_HWCACHE_ALI !! 693 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
611 } 694 }
612 695
613 /** 696 /**
614 * prepare_kernel_cred - Prepare a set of cred 697 * prepare_kernel_cred - Prepare a set of credentials for a kernel service
615 * @daemon: A userspace daemon to be used as a 698 * @daemon: A userspace daemon to be used as a reference
616 * 699 *
617 * Prepare a set of credentials for a kernel s 700 * Prepare a set of credentials for a kernel service. This can then be used to
618 * override a task's own credentials so that w 701 * override a task's own credentials so that work can be done on behalf of that
619 * task that requires a different subjective c 702 * task that requires a different subjective context.
620 * 703 *
621 * @daemon is used to provide a base cred, wit !! 704 * @daemon is used to provide a base for the security record, but can be NULL.
622 * that; if this is "&init_task", they'll be s !! 705 * If @daemon is supplied, then the security data will be derived from that;
623 * capabilities, and no keys. !! 706 * otherwise they'll be set to 0 and no groups, full capabilities and no keys.
624 * 707 *
625 * The caller may change these controls afterw 708 * The caller may change these controls afterwards if desired.
626 * 709 *
627 * Returns the new credentials or NULL if out 710 * Returns the new credentials or NULL if out of memory.
628 */ 711 */
629 struct cred *prepare_kernel_cred(struct task_s 712 struct cred *prepare_kernel_cred(struct task_struct *daemon)
630 { 713 {
631 const struct cred *old; 714 const struct cred *old;
632 struct cred *new; 715 struct cred *new;
633 716
634 if (WARN_ON_ONCE(!daemon)) <<
635 return NULL; <<
636 <<
637 new = kmem_cache_alloc(cred_jar, GFP_K 717 new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
638 if (!new) 718 if (!new)
639 return NULL; 719 return NULL;
640 720
641 kdebug("prepare_kernel_cred() alloc %p 721 kdebug("prepare_kernel_cred() alloc %p", new);
642 722
643 old = get_task_cred(daemon); !! 723 if (daemon)
>> 724 old = get_task_cred(daemon);
>> 725 else
>> 726 old = get_cred(&init_cred);
>> 727
>> 728 validate_creds(old);
644 729
645 *new = *old; 730 *new = *old;
646 new->non_rcu = 0; 731 new->non_rcu = 0;
647 atomic_long_set(&new->usage, 1); !! 732 atomic_set(&new->usage, 1);
>> 733 set_cred_subscribers(new, 0);
648 get_uid(new->user); 734 get_uid(new->user);
649 get_user_ns(new->user_ns); 735 get_user_ns(new->user_ns);
650 get_group_info(new->group_info); 736 get_group_info(new->group_info);
651 737
652 #ifdef CONFIG_KEYS 738 #ifdef CONFIG_KEYS
653 new->session_keyring = NULL; 739 new->session_keyring = NULL;
654 new->process_keyring = NULL; 740 new->process_keyring = NULL;
655 new->thread_keyring = NULL; 741 new->thread_keyring = NULL;
656 new->request_key_auth = NULL; 742 new->request_key_auth = NULL;
657 new->jit_keyring = KEY_REQKEY_DEFL_THR 743 new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
658 #endif 744 #endif
659 745
660 #ifdef CONFIG_SECURITY 746 #ifdef CONFIG_SECURITY
661 new->security = NULL; 747 new->security = NULL;
662 #endif 748 #endif
663 new->ucounts = get_ucounts(new->ucount 749 new->ucounts = get_ucounts(new->ucounts);
664 if (!new->ucounts) 750 if (!new->ucounts)
665 goto error; 751 goto error;
666 752
667 if (security_prepare_creds(new, old, G 753 if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
668 goto error; 754 goto error;
669 755
670 put_cred(old); 756 put_cred(old);
>> 757 validate_creds(new);
671 return new; 758 return new;
672 759
673 error: 760 error:
674 put_cred(new); 761 put_cred(new);
675 put_cred(old); 762 put_cred(old);
676 return NULL; 763 return NULL;
677 } 764 }
678 EXPORT_SYMBOL(prepare_kernel_cred); 765 EXPORT_SYMBOL(prepare_kernel_cred);
679 766
680 /** 767 /**
681 * set_security_override - Set the security ID 768 * set_security_override - Set the security ID in a set of credentials
682 * @new: The credentials to alter 769 * @new: The credentials to alter
683 * @secid: The LSM security ID to set 770 * @secid: The LSM security ID to set
684 * 771 *
685 * Set the LSM security ID in a set of credent 772 * Set the LSM security ID in a set of credentials so that the subjective
686 * security is overridden when an alternative 773 * security is overridden when an alternative set of credentials is used.
687 */ 774 */
688 int set_security_override(struct cred *new, u3 775 int set_security_override(struct cred *new, u32 secid)
689 { 776 {
690 return security_kernel_act_as(new, sec 777 return security_kernel_act_as(new, secid);
691 } 778 }
692 EXPORT_SYMBOL(set_security_override); 779 EXPORT_SYMBOL(set_security_override);
693 780
694 /** 781 /**
695 * set_security_override_from_ctx - Set the se 782 * set_security_override_from_ctx - Set the security ID in a set of credentials
696 * @new: The credentials to alter 783 * @new: The credentials to alter
697 * @secctx: The LSM security context to genera 784 * @secctx: The LSM security context to generate the security ID from.
698 * 785 *
699 * Set the LSM security ID in a set of credent 786 * Set the LSM security ID in a set of credentials so that the subjective
700 * security is overridden when an alternative 787 * security is overridden when an alternative set of credentials is used. The
701 * security ID is specified in string form as 788 * security ID is specified in string form as a security context to be
702 * interpreted by the LSM. 789 * interpreted by the LSM.
703 */ 790 */
704 int set_security_override_from_ctx(struct cred 791 int set_security_override_from_ctx(struct cred *new, const char *secctx)
705 { 792 {
706 u32 secid; 793 u32 secid;
707 int ret; 794 int ret;
708 795
709 ret = security_secctx_to_secid(secctx, 796 ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
710 if (ret < 0) 797 if (ret < 0)
711 return ret; 798 return ret;
712 799
713 return set_security_override(new, seci 800 return set_security_override(new, secid);
714 } 801 }
715 EXPORT_SYMBOL(set_security_override_from_ctx); 802 EXPORT_SYMBOL(set_security_override_from_ctx);
716 803
717 /** 804 /**
718 * set_create_files_as - Set the LSM file crea 805 * set_create_files_as - Set the LSM file create context in a set of credentials
719 * @new: The credentials to alter 806 * @new: The credentials to alter
720 * @inode: The inode to take the context from 807 * @inode: The inode to take the context from
721 * 808 *
722 * Change the LSM file creation context in a s 809 * Change the LSM file creation context in a set of credentials to be the same
723 * as the object context of the specified inod 810 * as the object context of the specified inode, so that the new inodes have
724 * the same MAC context as that inode. 811 * the same MAC context as that inode.
725 */ 812 */
726 int set_create_files_as(struct cred *new, stru 813 int set_create_files_as(struct cred *new, struct inode *inode)
727 { 814 {
728 if (!uid_valid(inode->i_uid) || !gid_v 815 if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
729 return -EINVAL; 816 return -EINVAL;
730 new->fsuid = inode->i_uid; 817 new->fsuid = inode->i_uid;
731 new->fsgid = inode->i_gid; 818 new->fsgid = inode->i_gid;
732 return security_kernel_create_files_as 819 return security_kernel_create_files_as(new, inode);
733 } 820 }
734 EXPORT_SYMBOL(set_create_files_as); 821 EXPORT_SYMBOL(set_create_files_as);
>> 822
>> 823 #ifdef CONFIG_DEBUG_CREDENTIALS
>> 824
>> 825 bool creds_are_invalid(const struct cred *cred)
>> 826 {
>> 827 if (cred->magic != CRED_MAGIC)
>> 828 return true;
>> 829 return false;
>> 830 }
>> 831 EXPORT_SYMBOL(creds_are_invalid);
>> 832
>> 833 /*
>> 834 * dump invalid credentials
>> 835 */
>> 836 static void dump_invalid_creds(const struct cred *cred, const char *label,
>> 837 const struct task_struct *tsk)
>> 838 {
>> 839 printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
>> 840 label, cred,
>> 841 cred == &init_cred ? "[init]" : "",
>> 842 cred == tsk->real_cred ? "[real]" : "",
>> 843 cred == tsk->cred ? "[eff]" : "");
>> 844 printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
>> 845 cred->magic, cred->put_addr);
>> 846 printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
>> 847 atomic_read(&cred->usage),
>> 848 read_cred_subscribers(cred));
>> 849 printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
>> 850 from_kuid_munged(&init_user_ns, cred->uid),
>> 851 from_kuid_munged(&init_user_ns, cred->euid),
>> 852 from_kuid_munged(&init_user_ns, cred->suid),
>> 853 from_kuid_munged(&init_user_ns, cred->fsuid));
>> 854 printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
>> 855 from_kgid_munged(&init_user_ns, cred->gid),
>> 856 from_kgid_munged(&init_user_ns, cred->egid),
>> 857 from_kgid_munged(&init_user_ns, cred->sgid),
>> 858 from_kgid_munged(&init_user_ns, cred->fsgid));
>> 859 #ifdef CONFIG_SECURITY
>> 860 printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
>> 861 if ((unsigned long) cred->security >= PAGE_SIZE &&
>> 862 (((unsigned long) cred->security & 0xffffff00) !=
>> 863 (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
>> 864 printk(KERN_ERR "CRED: ->security {%x, %x}\n",
>> 865 ((u32*)cred->security)[0],
>> 866 ((u32*)cred->security)[1]);
>> 867 #endif
>> 868 }
>> 869
>> 870 /*
>> 871 * report use of invalid credentials
>> 872 */
>> 873 void __noreturn __invalid_creds(const struct cred *cred, const char *file, unsigned line)
>> 874 {
>> 875 printk(KERN_ERR "CRED: Invalid credentials\n");
>> 876 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
>> 877 dump_invalid_creds(cred, "Specified", current);
>> 878 BUG();
>> 879 }
>> 880 EXPORT_SYMBOL(__invalid_creds);
>> 881
>> 882 /*
>> 883 * check the credentials on a process
>> 884 */
>> 885 void __validate_process_creds(struct task_struct *tsk,
>> 886 const char *file, unsigned line)
>> 887 {
>> 888 if (tsk->cred == tsk->real_cred) {
>> 889 if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
>> 890 creds_are_invalid(tsk->cred)))
>> 891 goto invalid_creds;
>> 892 } else {
>> 893 if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
>> 894 read_cred_subscribers(tsk->cred) < 1 ||
>> 895 creds_are_invalid(tsk->real_cred) ||
>> 896 creds_are_invalid(tsk->cred)))
>> 897 goto invalid_creds;
>> 898 }
>> 899 return;
>> 900
>> 901 invalid_creds:
>> 902 printk(KERN_ERR "CRED: Invalid process credentials\n");
>> 903 printk(KERN_ERR "CRED: At %s:%u\n", file, line);
>> 904
>> 905 dump_invalid_creds(tsk->real_cred, "Real", tsk);
>> 906 if (tsk->cred != tsk->real_cred)
>> 907 dump_invalid_creds(tsk->cred, "Effective", tsk);
>> 908 else
>> 909 printk(KERN_ERR "CRED: Effective creds == Real creds\n");
>> 910 BUG();
>> 911 }
>> 912 EXPORT_SYMBOL(__validate_process_creds);
>> 913
>> 914 /*
>> 915 * check creds for do_exit()
>> 916 */
>> 917 void validate_creds_for_do_exit(struct task_struct *tsk)
>> 918 {
>> 919 kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
>> 920 tsk->real_cred, tsk->cred,
>> 921 atomic_read(&tsk->cred->usage),
>> 922 read_cred_subscribers(tsk->cred));
>> 923
>> 924 __validate_process_creds(tsk, __FILE__, __LINE__);
>> 925 }
>> 926
>> 927 #endif /* CONFIG_DEBUG_CREDENTIALS */
735 928
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