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