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