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