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98870ab0 | 1 | /* Credentials management - see Documentation/credentials.txt |
9e2b2dc4 DH |
2 | * |
3 | * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. | |
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. | |
10 | */ | |
11 | ||
12 | #ifndef _LINUX_CRED_H | |
13 | #define _LINUX_CRED_H | |
14 | ||
b6dff3ec | 15 | #include <linux/capability.h> |
b2e1feaf | 16 | #include <linux/init.h> |
b6dff3ec DH |
17 | #include <linux/key.h> |
18 | #include <asm/atomic.h> | |
19 | ||
20 | struct user_struct; | |
21 | struct cred; | |
3a3b7ce9 | 22 | struct inode; |
b6dff3ec DH |
23 | |
24 | /* | |
25 | * COW Supplementary groups list | |
26 | */ | |
27 | #define NGROUPS_SMALL 32 | |
28 | #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t))) | |
29 | ||
30 | struct group_info { | |
31 | atomic_t usage; | |
32 | int ngroups; | |
33 | int nblocks; | |
34 | gid_t small_block[NGROUPS_SMALL]; | |
35 | gid_t *blocks[0]; | |
36 | }; | |
37 | ||
38 | /** | |
39 | * get_group_info - Get a reference to a group info structure | |
40 | * @group_info: The group info to reference | |
41 | * | |
86a264ab DH |
42 | * This gets a reference to a set of supplementary groups. |
43 | * | |
44 | * If the caller is accessing a task's credentials, they must hold the RCU read | |
45 | * lock when reading. | |
b6dff3ec | 46 | */ |
86a264ab DH |
47 | static inline struct group_info *get_group_info(struct group_info *gi) |
48 | { | |
49 | atomic_inc(&gi->usage); | |
50 | return gi; | |
51 | } | |
b6dff3ec DH |
52 | |
53 | /** | |
54 | * put_group_info - Release a reference to a group info structure | |
55 | * @group_info: The group info to release | |
56 | */ | |
57 | #define put_group_info(group_info) \ | |
58 | do { \ | |
59 | if (atomic_dec_and_test(&(group_info)->usage)) \ | |
60 | groups_free(group_info); \ | |
61 | } while (0) | |
62 | ||
63 | extern struct group_info *groups_alloc(int); | |
18b6e041 | 64 | extern struct group_info init_groups; |
b6dff3ec DH |
65 | extern void groups_free(struct group_info *); |
66 | extern int set_current_groups(struct group_info *); | |
67 | extern int set_groups(struct cred *, struct group_info *); | |
86a264ab | 68 | extern int groups_search(const struct group_info *, gid_t); |
b6dff3ec DH |
69 | |
70 | /* access the groups "array" with this macro */ | |
71 | #define GROUP_AT(gi, i) \ | |
72 | ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK]) | |
73 | ||
74 | extern int in_group_p(gid_t); | |
75 | extern int in_egroup_p(gid_t); | |
76 | ||
bb952bb9 DH |
77 | /* |
78 | * The common credentials for a thread group | |
79 | * - shared by CLONE_THREAD | |
80 | */ | |
81 | #ifdef CONFIG_KEYS | |
82 | struct thread_group_cred { | |
83 | atomic_t usage; | |
84 | pid_t tgid; /* thread group process ID */ | |
85 | spinlock_t lock; | |
86 | struct key *session_keyring; /* keyring inherited over fork */ | |
87 | struct key *process_keyring; /* keyring private to this process */ | |
88 | struct rcu_head rcu; /* RCU deletion hook */ | |
89 | }; | |
90 | #endif | |
91 | ||
b6dff3ec DH |
92 | /* |
93 | * The security context of a task | |
94 | * | |
95 | * The parts of the context break down into two categories: | |
96 | * | |
97 | * (1) The objective context of a task. These parts are used when some other | |
98 | * task is attempting to affect this one. | |
99 | * | |
100 | * (2) The subjective context. These details are used when the task is acting | |
101 | * upon another object, be that a file, a task, a key or whatever. | |
102 | * | |
103 | * Note that some members of this structure belong to both categories - the | |
104 | * LSM security pointer for instance. | |
105 | * | |
106 | * A task has two security pointers. task->real_cred points to the objective | |
107 | * context that defines that task's actual details. The objective part of this | |
108 | * context is used whenever that task is acted upon. | |
109 | * | |
110 | * task->cred points to the subjective context that defines the details of how | |
111 | * that task is going to act upon another object. This may be overridden | |
112 | * temporarily to point to another security context, but normally points to the | |
113 | * same context as task->real_cred. | |
114 | */ | |
115 | struct cred { | |
116 | atomic_t usage; | |
e0e81739 DH |
117 | #ifdef CONFIG_DEBUG_CREDENTIALS |
118 | atomic_t subscribers; /* number of processes subscribed */ | |
119 | void *put_addr; | |
120 | unsigned magic; | |
121 | #define CRED_MAGIC 0x43736564 | |
122 | #define CRED_MAGIC_DEAD 0x44656144 | |
123 | #endif | |
b6dff3ec DH |
124 | uid_t uid; /* real UID of the task */ |
125 | gid_t gid; /* real GID of the task */ | |
126 | uid_t suid; /* saved UID of the task */ | |
127 | gid_t sgid; /* saved GID of the task */ | |
128 | uid_t euid; /* effective UID of the task */ | |
129 | gid_t egid; /* effective GID of the task */ | |
130 | uid_t fsuid; /* UID for VFS ops */ | |
131 | gid_t fsgid; /* GID for VFS ops */ | |
132 | unsigned securebits; /* SUID-less security management */ | |
133 | kernel_cap_t cap_inheritable; /* caps our children can inherit */ | |
134 | kernel_cap_t cap_permitted; /* caps we're permitted */ | |
135 | kernel_cap_t cap_effective; /* caps we can actually use */ | |
136 | kernel_cap_t cap_bset; /* capability bounding set */ | |
137 | #ifdef CONFIG_KEYS | |
138 | unsigned char jit_keyring; /* default keyring to attach requested | |
139 | * keys to */ | |
140 | struct key *thread_keyring; /* keyring private to this thread */ | |
141 | struct key *request_key_auth; /* assumed request_key authority */ | |
bb952bb9 | 142 | struct thread_group_cred *tgcred; /* thread-group shared credentials */ |
b6dff3ec DH |
143 | #endif |
144 | #ifdef CONFIG_SECURITY | |
145 | void *security; /* subjective LSM security */ | |
146 | #endif | |
147 | struct user_struct *user; /* real user ID subscription */ | |
148 | struct group_info *group_info; /* supplementary groups for euid/fsgid */ | |
149 | struct rcu_head rcu; /* RCU deletion hook */ | |
b6dff3ec DH |
150 | }; |
151 | ||
f1752eec | 152 | extern void __put_cred(struct cred *); |
e0e81739 | 153 | extern void exit_creds(struct task_struct *); |
f1752eec | 154 | extern int copy_creds(struct task_struct *, unsigned long); |
ee18d64c | 155 | extern struct cred *cred_alloc_blank(void); |
d84f4f99 | 156 | extern struct cred *prepare_creds(void); |
a6f76f23 | 157 | extern struct cred *prepare_exec_creds(void); |
d84f4f99 DH |
158 | extern struct cred *prepare_usermodehelper_creds(void); |
159 | extern int commit_creds(struct cred *); | |
160 | extern void abort_creds(struct cred *); | |
3b11a1de DH |
161 | extern const struct cred *override_creds(const struct cred *); |
162 | extern void revert_creds(const struct cred *); | |
3a3b7ce9 DH |
163 | extern struct cred *prepare_kernel_cred(struct task_struct *); |
164 | extern int change_create_files_as(struct cred *, struct inode *); | |
165 | extern int set_security_override(struct cred *, u32); | |
166 | extern int set_security_override_from_ctx(struct cred *, const char *); | |
167 | extern int set_create_files_as(struct cred *, struct inode *); | |
d84f4f99 DH |
168 | extern void __init cred_init(void); |
169 | ||
e0e81739 DH |
170 | /* |
171 | * check for validity of credentials | |
172 | */ | |
173 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
174 | extern void __invalid_creds(const struct cred *, const char *, unsigned); | |
175 | extern void __validate_process_creds(struct task_struct *, | |
176 | const char *, unsigned); | |
177 | ||
178 | static inline bool creds_are_invalid(const struct cred *cred) | |
179 | { | |
180 | if (cred->magic != CRED_MAGIC) | |
181 | return true; | |
182 | if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers)) | |
183 | return true; | |
184 | #ifdef CONFIG_SECURITY_SELINUX | |
185 | if ((unsigned long) cred->security < PAGE_SIZE) | |
186 | return true; | |
187 | if ((*(u32*)cred->security & 0xffffff00) == | |
188 | (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)) | |
189 | return true; | |
190 | #endif | |
191 | return false; | |
192 | } | |
193 | ||
194 | static inline void __validate_creds(const struct cred *cred, | |
195 | const char *file, unsigned line) | |
196 | { | |
197 | if (unlikely(creds_are_invalid(cred))) | |
198 | __invalid_creds(cred, file, line); | |
199 | } | |
200 | ||
201 | #define validate_creds(cred) \ | |
202 | do { \ | |
203 | __validate_creds((cred), __FILE__, __LINE__); \ | |
204 | } while(0) | |
205 | ||
206 | #define validate_process_creds() \ | |
207 | do { \ | |
208 | __validate_process_creds(current, __FILE__, __LINE__); \ | |
209 | } while(0) | |
210 | ||
211 | extern void validate_creds_for_do_exit(struct task_struct *); | |
212 | #else | |
213 | static inline void validate_creds(const struct cred *cred) | |
214 | { | |
215 | } | |
216 | static inline void validate_creds_for_do_exit(struct task_struct *tsk) | |
217 | { | |
218 | } | |
219 | static inline void validate_process_creds(void) | |
220 | { | |
221 | } | |
222 | #endif | |
223 | ||
d84f4f99 DH |
224 | /** |
225 | * get_new_cred - Get a reference on a new set of credentials | |
226 | * @cred: The new credentials to reference | |
227 | * | |
228 | * Get a reference on the specified set of new credentials. The caller must | |
229 | * release the reference. | |
230 | */ | |
231 | static inline struct cred *get_new_cred(struct cred *cred) | |
232 | { | |
233 | atomic_inc(&cred->usage); | |
234 | return cred; | |
235 | } | |
f1752eec DH |
236 | |
237 | /** | |
238 | * get_cred - Get a reference on a set of credentials | |
239 | * @cred: The credentials to reference | |
240 | * | |
241 | * Get a reference on the specified set of credentials. The caller must | |
242 | * release the reference. | |
98870ab0 DH |
243 | * |
244 | * This is used to deal with a committed set of credentials. Although the | |
245 | * pointer is const, this will temporarily discard the const and increment the | |
246 | * usage count. The purpose of this is to attempt to catch at compile time the | |
247 | * accidental alteration of a set of credentials that should be considered | |
248 | * immutable. | |
f1752eec | 249 | */ |
d84f4f99 | 250 | static inline const struct cred *get_cred(const struct cred *cred) |
f1752eec | 251 | { |
1c388ad0 | 252 | struct cred *nonconst_cred = (struct cred *) cred; |
e0e81739 | 253 | validate_creds(cred); |
1c388ad0 | 254 | return get_new_cred(nonconst_cred); |
f1752eec DH |
255 | } |
256 | ||
257 | /** | |
258 | * put_cred - Release a reference to a set of credentials | |
259 | * @cred: The credentials to release | |
260 | * | |
261 | * Release a reference to a set of credentials, deleting them when the last ref | |
262 | * is released. | |
98870ab0 DH |
263 | * |
264 | * This takes a const pointer to a set of credentials because the credentials | |
265 | * on task_struct are attached by const pointers to prevent accidental | |
266 | * alteration of otherwise immutable credential sets. | |
f1752eec | 267 | */ |
c69e8d9c | 268 | static inline void put_cred(const struct cred *_cred) |
f1752eec | 269 | { |
c69e8d9c | 270 | struct cred *cred = (struct cred *) _cred; |
d84f4f99 | 271 | |
e0e81739 | 272 | validate_creds(cred); |
f1752eec DH |
273 | if (atomic_dec_and_test(&(cred)->usage)) |
274 | __put_cred(cred); | |
275 | } | |
276 | ||
86a264ab | 277 | /** |
3b11a1de | 278 | * current_cred - Access the current task's subjective credentials |
86a264ab | 279 | * |
3b11a1de | 280 | * Access the subjective credentials of the current task. |
86a264ab DH |
281 | */ |
282 | #define current_cred() \ | |
283 | (current->cred) | |
284 | ||
285 | /** | |
3b11a1de | 286 | * __task_cred - Access a task's objective credentials |
86a264ab DH |
287 | * @task: The task to query |
288 | * | |
3b11a1de DH |
289 | * Access the objective credentials of a task. The caller must hold the RCU |
290 | * readlock. | |
86a264ab DH |
291 | * |
292 | * The caller must make sure task doesn't go away, either by holding a ref on | |
293 | * task or by holding tasklist_lock to prevent it from being unlinked. | |
294 | */ | |
295 | #define __task_cred(task) \ | |
3b11a1de | 296 | ((const struct cred *)(rcu_dereference((task)->real_cred))) |
86a264ab DH |
297 | |
298 | /** | |
3b11a1de | 299 | * get_task_cred - Get another task's objective credentials |
86a264ab DH |
300 | * @task: The task to query |
301 | * | |
3b11a1de DH |
302 | * Get the objective credentials of a task, pinning them so that they can't go |
303 | * away. Accessing a task's credentials directly is not permitted. | |
86a264ab DH |
304 | * |
305 | * The caller must make sure task doesn't go away, either by holding a ref on | |
306 | * task or by holding tasklist_lock to prevent it from being unlinked. | |
307 | */ | |
308 | #define get_task_cred(task) \ | |
309 | ({ \ | |
310 | struct cred *__cred; \ | |
311 | rcu_read_lock(); \ | |
312 | __cred = (struct cred *) __task_cred((task)); \ | |
313 | get_cred(__cred); \ | |
314 | rcu_read_unlock(); \ | |
315 | __cred; \ | |
316 | }) | |
317 | ||
318 | /** | |
3b11a1de | 319 | * get_current_cred - Get the current task's subjective credentials |
86a264ab | 320 | * |
3b11a1de DH |
321 | * Get the subjective credentials of the current task, pinning them so that |
322 | * they can't go away. Accessing the current task's credentials directly is | |
323 | * not permitted. | |
86a264ab DH |
324 | */ |
325 | #define get_current_cred() \ | |
326 | (get_cred(current_cred())) | |
327 | ||
328 | /** | |
329 | * get_current_user - Get the current task's user_struct | |
330 | * | |
331 | * Get the user record of the current task, pinning it so that it can't go | |
332 | * away. | |
333 | */ | |
334 | #define get_current_user() \ | |
335 | ({ \ | |
336 | struct user_struct *__u; \ | |
337 | struct cred *__cred; \ | |
338 | __cred = (struct cred *) current_cred(); \ | |
339 | __u = get_uid(__cred->user); \ | |
340 | __u; \ | |
341 | }) | |
342 | ||
343 | /** | |
344 | * get_current_groups - Get the current task's supplementary group list | |
345 | * | |
346 | * Get the supplementary group list of the current task, pinning it so that it | |
347 | * can't go away. | |
348 | */ | |
349 | #define get_current_groups() \ | |
350 | ({ \ | |
351 | struct group_info *__groups; \ | |
352 | struct cred *__cred; \ | |
353 | __cred = (struct cred *) current_cred(); \ | |
354 | __groups = get_group_info(__cred->group_info); \ | |
355 | __groups; \ | |
356 | }) | |
357 | ||
d84f4f99 DH |
358 | #define task_cred_xxx(task, xxx) \ |
359 | ({ \ | |
360 | __typeof__(((struct cred *)NULL)->xxx) ___val; \ | |
361 | rcu_read_lock(); \ | |
362 | ___val = __task_cred((task))->xxx; \ | |
363 | rcu_read_unlock(); \ | |
364 | ___val; \ | |
86a264ab DH |
365 | }) |
366 | ||
367 | #define task_uid(task) (task_cred_xxx((task), uid)) | |
368 | #define task_euid(task) (task_cred_xxx((task), euid)) | |
369 | ||
370 | #define current_cred_xxx(xxx) \ | |
371 | ({ \ | |
372 | current->cred->xxx; \ | |
373 | }) | |
374 | ||
375 | #define current_uid() (current_cred_xxx(uid)) | |
376 | #define current_gid() (current_cred_xxx(gid)) | |
377 | #define current_euid() (current_cred_xxx(euid)) | |
378 | #define current_egid() (current_cred_xxx(egid)) | |
379 | #define current_suid() (current_cred_xxx(suid)) | |
380 | #define current_sgid() (current_cred_xxx(sgid)) | |
381 | #define current_fsuid() (current_cred_xxx(fsuid)) | |
382 | #define current_fsgid() (current_cred_xxx(fsgid)) | |
383 | #define current_cap() (current_cred_xxx(cap_effective)) | |
384 | #define current_user() (current_cred_xxx(user)) | |
18b6e041 | 385 | #define current_user_ns() (current_cred_xxx(user)->user_ns) |
86a264ab DH |
386 | #define current_security() (current_cred_xxx(security)) |
387 | ||
388 | #define current_uid_gid(_uid, _gid) \ | |
389 | do { \ | |
390 | const struct cred *__cred; \ | |
391 | __cred = current_cred(); \ | |
392 | *(_uid) = __cred->uid; \ | |
393 | *(_gid) = __cred->gid; \ | |
394 | } while(0) | |
395 | ||
396 | #define current_euid_egid(_euid, _egid) \ | |
397 | do { \ | |
398 | const struct cred *__cred; \ | |
399 | __cred = current_cred(); \ | |
400 | *(_euid) = __cred->euid; \ | |
401 | *(_egid) = __cred->egid; \ | |
402 | } while(0) | |
403 | ||
404 | #define current_fsuid_fsgid(_fsuid, _fsgid) \ | |
405 | do { \ | |
406 | const struct cred *__cred; \ | |
407 | __cred = current_cred(); \ | |
408 | *(_fsuid) = __cred->fsuid; \ | |
409 | *(_fsgid) = __cred->fsgid; \ | |
410 | } while(0) | |
411 | ||
9e2b2dc4 | 412 | #endif /* _LINUX_CRED_H */ |