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