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