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d410fa4e | 1 | /* Credentials management - see Documentation/security/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 | 17 | #include <linux/key.h> |
ed868a56 | 18 | #include <linux/selinux.h> |
60063497 | 19 | #include <linux/atomic.h> |
ae2975bc | 20 | #include <linux/uidgid.h> |
b6dff3ec DH |
21 | |
22 | struct user_struct; | |
23 | struct cred; | |
3a3b7ce9 | 24 | struct inode; |
b6dff3ec DH |
25 | |
26 | /* | |
27 | * COW Supplementary groups list | |
28 | */ | |
29 | #define NGROUPS_SMALL 32 | |
ae2975bc | 30 | #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t))) |
b6dff3ec DH |
31 | |
32 | struct group_info { | |
33 | atomic_t usage; | |
34 | int ngroups; | |
35 | int nblocks; | |
ae2975bc EB |
36 | kgid_t small_block[NGROUPS_SMALL]; |
37 | kgid_t *blocks[0]; | |
b6dff3ec DH |
38 | }; |
39 | ||
40 | /** | |
41 | * get_group_info - Get a reference to a group info structure | |
42 | * @group_info: The group info to reference | |
43 | * | |
86a264ab DH |
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. | |
b6dff3ec | 48 | */ |
86a264ab DH |
49 | static inline struct group_info *get_group_info(struct group_info *gi) |
50 | { | |
51 | atomic_inc(&gi->usage); | |
52 | return gi; | |
53 | } | |
b6dff3ec DH |
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); | |
18b6e041 | 66 | extern struct group_info init_groups; |
b6dff3ec DH |
67 | extern void groups_free(struct group_info *); |
68 | extern int set_current_groups(struct group_info *); | |
8f6c5ffc | 69 | extern void set_groups(struct cred *, struct group_info *); |
ae2975bc | 70 | extern int groups_search(const struct group_info *, kgid_t); |
7ff4d90b | 71 | extern bool may_setgroups(void); |
b6dff3ec DH |
72 | |
73 | /* access the groups "array" with this macro */ | |
74 | #define GROUP_AT(gi, i) \ | |
75 | ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK]) | |
76 | ||
72cda3d1 EB |
77 | extern int in_group_p(kgid_t); |
78 | extern int in_egroup_p(kgid_t); | |
b6dff3ec DH |
79 | |
80 | /* | |
81 | * The security context of a task | |
82 | * | |
83 | * The parts of the context break down into two categories: | |
84 | * | |
85 | * (1) The objective context of a task. These parts are used when some other | |
86 | * task is attempting to affect this one. | |
87 | * | |
88 | * (2) The subjective context. These details are used when the task is acting | |
89 | * upon another object, be that a file, a task, a key or whatever. | |
90 | * | |
91 | * Note that some members of this structure belong to both categories - the | |
92 | * LSM security pointer for instance. | |
93 | * | |
94 | * A task has two security pointers. task->real_cred points to the objective | |
95 | * context that defines that task's actual details. The objective part of this | |
96 | * context is used whenever that task is acted upon. | |
97 | * | |
98 | * task->cred points to the subjective context that defines the details of how | |
99 | * that task is going to act upon another object. This may be overridden | |
100 | * temporarily to point to another security context, but normally points to the | |
101 | * same context as task->real_cred. | |
102 | */ | |
103 | struct cred { | |
104 | atomic_t usage; | |
e0e81739 DH |
105 | #ifdef CONFIG_DEBUG_CREDENTIALS |
106 | atomic_t subscribers; /* number of processes subscribed */ | |
107 | void *put_addr; | |
108 | unsigned magic; | |
109 | #define CRED_MAGIC 0x43736564 | |
110 | #define CRED_MAGIC_DEAD 0x44656144 | |
111 | #endif | |
078de5f7 EB |
112 | kuid_t uid; /* real UID of the task */ |
113 | kgid_t gid; /* real GID of the task */ | |
114 | kuid_t suid; /* saved UID of the task */ | |
115 | kgid_t sgid; /* saved GID of the task */ | |
116 | kuid_t euid; /* effective UID of the task */ | |
117 | kgid_t egid; /* effective GID of the task */ | |
118 | kuid_t fsuid; /* UID for VFS ops */ | |
119 | kgid_t fsgid; /* GID for VFS ops */ | |
b6dff3ec DH |
120 | unsigned securebits; /* SUID-less security management */ |
121 | kernel_cap_t cap_inheritable; /* caps our children can inherit */ | |
122 | kernel_cap_t cap_permitted; /* caps we're permitted */ | |
123 | kernel_cap_t cap_effective; /* caps we can actually use */ | |
124 | kernel_cap_t cap_bset; /* capability bounding set */ | |
125 | #ifdef CONFIG_KEYS | |
126 | unsigned char jit_keyring; /* default keyring to attach requested | |
127 | * keys to */ | |
3a50597d DH |
128 | struct key __rcu *session_keyring; /* keyring inherited over fork */ |
129 | struct key *process_keyring; /* keyring private to this process */ | |
b6dff3ec DH |
130 | struct key *thread_keyring; /* keyring private to this thread */ |
131 | struct key *request_key_auth; /* assumed request_key authority */ | |
132 | #endif | |
133 | #ifdef CONFIG_SECURITY | |
134 | void *security; /* subjective LSM security */ | |
135 | #endif | |
136 | struct user_struct *user; /* real user ID subscription */ | |
0093ccb6 | 137 | struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */ |
b6dff3ec DH |
138 | struct group_info *group_info; /* supplementary groups for euid/fsgid */ |
139 | struct rcu_head rcu; /* RCU deletion hook */ | |
b6dff3ec DH |
140 | }; |
141 | ||
f1752eec | 142 | extern void __put_cred(struct cred *); |
e0e81739 | 143 | extern void exit_creds(struct task_struct *); |
f1752eec | 144 | extern int copy_creds(struct task_struct *, unsigned long); |
de09a977 | 145 | extern const struct cred *get_task_cred(struct task_struct *); |
ee18d64c | 146 | extern struct cred *cred_alloc_blank(void); |
d84f4f99 | 147 | extern struct cred *prepare_creds(void); |
a6f76f23 | 148 | extern struct cred *prepare_exec_creds(void); |
d84f4f99 DH |
149 | extern int commit_creds(struct cred *); |
150 | extern void abort_creds(struct cred *); | |
3b11a1de DH |
151 | extern const struct cred *override_creds(const struct cred *); |
152 | extern void revert_creds(const struct cred *); | |
3a3b7ce9 DH |
153 | extern struct cred *prepare_kernel_cred(struct task_struct *); |
154 | extern int change_create_files_as(struct cred *, struct inode *); | |
155 | extern int set_security_override(struct cred *, u32); | |
156 | extern int set_security_override_from_ctx(struct cred *, const char *); | |
157 | extern int set_create_files_as(struct cred *, struct inode *); | |
d84f4f99 DH |
158 | extern void __init cred_init(void); |
159 | ||
e0e81739 DH |
160 | /* |
161 | * check for validity of credentials | |
162 | */ | |
163 | #ifdef CONFIG_DEBUG_CREDENTIALS | |
164 | extern void __invalid_creds(const struct cred *, const char *, unsigned); | |
165 | extern void __validate_process_creds(struct task_struct *, | |
166 | const char *, unsigned); | |
167 | ||
74908a00 | 168 | extern bool creds_are_invalid(const struct cred *cred); |
e0e81739 DH |
169 | |
170 | static inline void __validate_creds(const struct cred *cred, | |
171 | const char *file, unsigned line) | |
172 | { | |
173 | if (unlikely(creds_are_invalid(cred))) | |
174 | __invalid_creds(cred, file, line); | |
175 | } | |
176 | ||
177 | #define validate_creds(cred) \ | |
178 | do { \ | |
179 | __validate_creds((cred), __FILE__, __LINE__); \ | |
180 | } while(0) | |
181 | ||
182 | #define validate_process_creds() \ | |
183 | do { \ | |
184 | __validate_process_creds(current, __FILE__, __LINE__); \ | |
185 | } while(0) | |
186 | ||
187 | extern void validate_creds_for_do_exit(struct task_struct *); | |
188 | #else | |
189 | static inline void validate_creds(const struct cred *cred) | |
190 | { | |
191 | } | |
192 | static inline void validate_creds_for_do_exit(struct task_struct *tsk) | |
193 | { | |
194 | } | |
195 | static inline void validate_process_creds(void) | |
196 | { | |
197 | } | |
198 | #endif | |
199 | ||
d84f4f99 DH |
200 | /** |
201 | * get_new_cred - Get a reference on a new set of credentials | |
202 | * @cred: The new credentials to reference | |
203 | * | |
204 | * Get a reference on the specified set of new credentials. The caller must | |
205 | * release the reference. | |
206 | */ | |
207 | static inline struct cred *get_new_cred(struct cred *cred) | |
208 | { | |
209 | atomic_inc(&cred->usage); | |
210 | return cred; | |
211 | } | |
f1752eec DH |
212 | |
213 | /** | |
214 | * get_cred - Get a reference on a set of credentials | |
215 | * @cred: The credentials to reference | |
216 | * | |
217 | * Get a reference on the specified set of credentials. The caller must | |
218 | * release the reference. | |
98870ab0 DH |
219 | * |
220 | * This is used to deal with a committed set of credentials. Although the | |
221 | * pointer is const, this will temporarily discard the const and increment the | |
222 | * usage count. The purpose of this is to attempt to catch at compile time the | |
223 | * accidental alteration of a set of credentials that should be considered | |
224 | * immutable. | |
f1752eec | 225 | */ |
d84f4f99 | 226 | static inline const struct cred *get_cred(const struct cred *cred) |
f1752eec | 227 | { |
1c388ad0 | 228 | struct cred *nonconst_cred = (struct cred *) cred; |
e0e81739 | 229 | validate_creds(cred); |
1c388ad0 | 230 | return get_new_cred(nonconst_cred); |
f1752eec DH |
231 | } |
232 | ||
233 | /** | |
234 | * put_cred - Release a reference to a set of credentials | |
235 | * @cred: The credentials to release | |
236 | * | |
237 | * Release a reference to a set of credentials, deleting them when the last ref | |
238 | * is released. | |
98870ab0 DH |
239 | * |
240 | * This takes a const pointer to a set of credentials because the credentials | |
241 | * on task_struct are attached by const pointers to prevent accidental | |
242 | * alteration of otherwise immutable credential sets. | |
f1752eec | 243 | */ |
c69e8d9c | 244 | static inline void put_cred(const struct cred *_cred) |
f1752eec | 245 | { |
c69e8d9c | 246 | struct cred *cred = (struct cred *) _cred; |
d84f4f99 | 247 | |
e0e81739 | 248 | validate_creds(cred); |
f1752eec DH |
249 | if (atomic_dec_and_test(&(cred)->usage)) |
250 | __put_cred(cred); | |
251 | } | |
252 | ||
86a264ab | 253 | /** |
3b11a1de | 254 | * current_cred - Access the current task's subjective credentials |
86a264ab | 255 | * |
32955148 AV |
256 | * Access the subjective credentials of the current task. RCU-safe, |
257 | * since nobody else can modify it. | |
86a264ab DH |
258 | */ |
259 | #define current_cred() \ | |
27e4e436 | 260 | rcu_dereference_protected(current->cred, 1) |
86a264ab | 261 | |
ae4b884f JL |
262 | /** |
263 | * current_real_cred - Access the current task's objective credentials | |
264 | * | |
265 | * Access the objective credentials of the current task. RCU-safe, | |
266 | * since nobody else can modify it. | |
267 | */ | |
268 | #define current_real_cred() \ | |
269 | rcu_dereference_protected(current->real_cred, 1) | |
270 | ||
86a264ab | 271 | /** |
3b11a1de | 272 | * __task_cred - Access a task's objective credentials |
86a264ab DH |
273 | * @task: The task to query |
274 | * | |
3b11a1de | 275 | * Access the objective credentials of a task. The caller must hold the RCU |
43e13cc1 | 276 | * readlock. |
86a264ab | 277 | * |
8f92054e DH |
278 | * The result of this function should not be passed directly to get_cred(); |
279 | * rather get_task_cred() should be used instead. | |
86a264ab | 280 | */ |
43e13cc1 ON |
281 | #define __task_cred(task) \ |
282 | rcu_dereference((task)->real_cred) | |
86a264ab | 283 | |
86a264ab | 284 | /** |
3b11a1de | 285 | * get_current_cred - Get the current task's subjective credentials |
86a264ab | 286 | * |
3b11a1de DH |
287 | * Get the subjective credentials of the current task, pinning them so that |
288 | * they can't go away. Accessing the current task's credentials directly is | |
289 | * not permitted. | |
86a264ab DH |
290 | */ |
291 | #define get_current_cred() \ | |
292 | (get_cred(current_cred())) | |
293 | ||
294 | /** | |
295 | * get_current_user - Get the current task's user_struct | |
296 | * | |
297 | * Get the user record of the current task, pinning it so that it can't go | |
298 | * away. | |
299 | */ | |
300 | #define get_current_user() \ | |
301 | ({ \ | |
302 | struct user_struct *__u; \ | |
638a8439 | 303 | const struct cred *__cred; \ |
32955148 | 304 | __cred = current_cred(); \ |
86a264ab DH |
305 | __u = get_uid(__cred->user); \ |
306 | __u; \ | |
307 | }) | |
308 | ||
309 | /** | |
310 | * get_current_groups - Get the current task's supplementary group list | |
311 | * | |
312 | * Get the supplementary group list of the current task, pinning it so that it | |
313 | * can't go away. | |
314 | */ | |
315 | #define get_current_groups() \ | |
316 | ({ \ | |
317 | struct group_info *__groups; \ | |
638a8439 | 318 | const struct cred *__cred; \ |
32955148 | 319 | __cred = current_cred(); \ |
86a264ab DH |
320 | __groups = get_group_info(__cred->group_info); \ |
321 | __groups; \ | |
322 | }) | |
323 | ||
d84f4f99 DH |
324 | #define task_cred_xxx(task, xxx) \ |
325 | ({ \ | |
326 | __typeof__(((struct cred *)NULL)->xxx) ___val; \ | |
327 | rcu_read_lock(); \ | |
328 | ___val = __task_cred((task))->xxx; \ | |
329 | rcu_read_unlock(); \ | |
330 | ___val; \ | |
86a264ab DH |
331 | }) |
332 | ||
333 | #define task_uid(task) (task_cred_xxx((task), uid)) | |
334 | #define task_euid(task) (task_cred_xxx((task), euid)) | |
335 | ||
336 | #define current_cred_xxx(xxx) \ | |
337 | ({ \ | |
32955148 | 338 | current_cred()->xxx; \ |
86a264ab DH |
339 | }) |
340 | ||
341 | #define current_uid() (current_cred_xxx(uid)) | |
342 | #define current_gid() (current_cred_xxx(gid)) | |
343 | #define current_euid() (current_cred_xxx(euid)) | |
344 | #define current_egid() (current_cred_xxx(egid)) | |
345 | #define current_suid() (current_cred_xxx(suid)) | |
346 | #define current_sgid() (current_cred_xxx(sgid)) | |
347 | #define current_fsuid() (current_cred_xxx(fsuid)) | |
348 | #define current_fsgid() (current_cred_xxx(fsgid)) | |
349 | #define current_cap() (current_cred_xxx(cap_effective)) | |
350 | #define current_user() (current_cred_xxx(user)) | |
351 | #define current_security() (current_cred_xxx(security)) | |
352 | ||
7e6bd8fa | 353 | extern struct user_namespace init_user_ns; |
47a150ed | 354 | #ifdef CONFIG_USER_NS |
f1c84dae | 355 | #define current_user_ns() (current_cred_xxx(user_ns)) |
47a150ed | 356 | #else |
f1c84dae | 357 | #define current_user_ns() (&init_user_ns) |
47a150ed SH |
358 | #endif |
359 | ||
3486740a | 360 | |
86a264ab DH |
361 | #define current_uid_gid(_uid, _gid) \ |
362 | do { \ | |
363 | const struct cred *__cred; \ | |
364 | __cred = current_cred(); \ | |
365 | *(_uid) = __cred->uid; \ | |
366 | *(_gid) = __cred->gid; \ | |
367 | } while(0) | |
368 | ||
369 | #define current_euid_egid(_euid, _egid) \ | |
370 | do { \ | |
371 | const struct cred *__cred; \ | |
372 | __cred = current_cred(); \ | |
373 | *(_euid) = __cred->euid; \ | |
374 | *(_egid) = __cred->egid; \ | |
375 | } while(0) | |
376 | ||
377 | #define current_fsuid_fsgid(_fsuid, _fsgid) \ | |
378 | do { \ | |
379 | const struct cred *__cred; \ | |
380 | __cred = current_cred(); \ | |
381 | *(_fsuid) = __cred->fsuid; \ | |
382 | *(_fsgid) = __cred->fsgid; \ | |
383 | } while(0) | |
384 | ||
9e2b2dc4 | 385 | #endif /* _LINUX_CRED_H */ |