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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 struct cred *cred_alloc_blank(void); |
157 | extern struct cred *prepare_creds(void); |
158 | extern struct cred *prepare_exec_creds(void); |
159 | extern struct cred *prepare_usermodehelper_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_task_cred - Get another task's objective credentials |
287 | * @task: The task to query |
288 | * |
289 | * Get the objective credentials of a task, pinning them so that they can't go |
290 | * away. Accessing a task's credentials directly is not permitted. |
291 | * |
292 | * The caller must make sure task doesn't go away, either by holding a ref on |
293 | * task or by holding tasklist_lock to prevent it from being unlinked. |
294 | */ |
295 | #define get_task_cred(task) \ |
296 | ({ \ |
297 | struct cred *__cred; \ |
298 | rcu_read_lock(); \ |
299 | __cred = (struct cred *) __task_cred((task)); \ |
300 | get_cred(__cred); \ |
301 | rcu_read_unlock(); \ |
302 | __cred; \ |
303 | }) |
304 | |
305 | /** |
306 | * get_current_cred - Get the current task's subjective credentials |
307 | * |
308 | * Get the subjective credentials of the current task, pinning them so that |
309 | * they can't go away. Accessing the current task's credentials directly is |
310 | * not permitted. |
311 | */ |
312 | #define get_current_cred() \ |
313 | (get_cred(current_cred())) |
314 | |
315 | /** |
316 | * get_current_user - Get the current task's user_struct |
317 | * |
318 | * Get the user record of the current task, pinning it so that it can't go |
319 | * away. |
320 | */ |
321 | #define get_current_user() \ |
322 | ({ \ |
323 | struct user_struct *__u; \ |
324 | struct cred *__cred; \ |
325 | __cred = (struct cred *) current_cred(); \ |
326 | __u = get_uid(__cred->user); \ |
327 | __u; \ |
328 | }) |
329 | |
330 | /** |
331 | * get_current_groups - Get the current task's supplementary group list |
332 | * |
333 | * Get the supplementary group list of the current task, pinning it so that it |
334 | * can't go away. |
335 | */ |
336 | #define get_current_groups() \ |
337 | ({ \ |
338 | struct group_info *__groups; \ |
339 | struct cred *__cred; \ |
340 | __cred = (struct cred *) current_cred(); \ |
341 | __groups = get_group_info(__cred->group_info); \ |
342 | __groups; \ |
343 | }) |
344 | |
345 | #define task_cred_xxx(task, xxx) \ |
346 | ({ \ |
347 | __typeof__(((struct cred *)NULL)->xxx) ___val; \ |
348 | rcu_read_lock(); \ |
349 | ___val = __task_cred((task))->xxx; \ |
350 | rcu_read_unlock(); \ |
351 | ___val; \ |
352 | }) |
353 | |
354 | #define task_uid(task) (task_cred_xxx((task), uid)) |
355 | #define task_euid(task) (task_cred_xxx((task), euid)) |
356 | |
357 | #define current_cred_xxx(xxx) \ |
358 | ({ \ |
359 | current->cred->xxx; \ |
360 | }) |
361 | |
362 | #define current_uid() (current_cred_xxx(uid)) |
363 | #define current_gid() (current_cred_xxx(gid)) |
364 | #define current_euid() (current_cred_xxx(euid)) |
365 | #define current_egid() (current_cred_xxx(egid)) |
366 | #define current_suid() (current_cred_xxx(suid)) |
367 | #define current_sgid() (current_cred_xxx(sgid)) |
368 | #define current_fsuid() (current_cred_xxx(fsuid)) |
369 | #define current_fsgid() (current_cred_xxx(fsgid)) |
370 | #define current_cap() (current_cred_xxx(cap_effective)) |
371 | #define current_user() (current_cred_xxx(user)) |
372 | #define current_user_ns() (current_cred_xxx(user)->user_ns) |
373 | #define current_security() (current_cred_xxx(security)) |
374 | |
375 | #define current_uid_gid(_uid, _gid) \ |
376 | do { \ |
377 | const struct cred *__cred; \ |
378 | __cred = current_cred(); \ |
379 | *(_uid) = __cred->uid; \ |
380 | *(_gid) = __cred->gid; \ |
381 | } while(0) |
382 | |
383 | #define current_euid_egid(_euid, _egid) \ |
384 | do { \ |
385 | const struct cred *__cred; \ |
386 | __cred = current_cred(); \ |
387 | *(_euid) = __cred->euid; \ |
388 | *(_egid) = __cred->egid; \ |
389 | } while(0) |
390 | |
391 | #define current_fsuid_fsgid(_fsuid, _fsgid) \ |
392 | do { \ |
393 | const struct cred *__cred; \ |
394 | __cred = current_cred(); \ |
395 | *(_fsuid) = __cred->fsuid; \ |
396 | *(_fsgid) = __cred->fsgid; \ |
397 | } while(0) |
398 | |
399 | #endif /* _LINUX_CRED_H */ |
400 |
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