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