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