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98870ab0 1/* Credentials management - see Documentation/credentials.txt
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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>
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17#include <linux/key.h>
18#include <asm/atomic.h>
19
20struct user_struct;
21struct cred;
3a3b7ce9 22struct inode;
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23
24/*
25 * COW Supplementary groups list
26 */
27#define NGROUPS_SMALL 32
28#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t)))
29
30struct group_info {
31 atomic_t usage;
32 int ngroups;
33 int nblocks;
34 gid_t small_block[NGROUPS_SMALL];
35 gid_t *blocks[0];
36};
37
38/**
39 * get_group_info - Get a reference to a group info structure
40 * @group_info: The group info to reference
41 *
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42 * This gets a reference to a set of supplementary groups.
43 *
44 * If the caller is accessing a task's credentials, they must hold the RCU read
45 * lock when reading.
b6dff3ec 46 */
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47static inline struct group_info *get_group_info(struct group_info *gi)
48{
49 atomic_inc(&gi->usage);
50 return gi;
51}
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52
53/**
54 * put_group_info - Release a reference to a group info structure
55 * @group_info: The group info to release
56 */
57#define put_group_info(group_info) \
58do { \
59 if (atomic_dec_and_test(&(group_info)->usage)) \
60 groups_free(group_info); \
61} while (0)
62
63extern struct group_info *groups_alloc(int);
18b6e041 64extern struct group_info init_groups;
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65extern void groups_free(struct group_info *);
66extern int set_current_groups(struct group_info *);
67extern int set_groups(struct cred *, struct group_info *);
86a264ab 68extern int groups_search(const struct group_info *, gid_t);
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69
70/* access the groups "array" with this macro */
71#define GROUP_AT(gi, i) \
72 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
73
74extern int in_group_p(gid_t);
75extern int in_egroup_p(gid_t);
76
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77/*
78 * The common credentials for a thread group
79 * - shared by CLONE_THREAD
80 */
81#ifdef CONFIG_KEYS
82struct thread_group_cred {
83 atomic_t usage;
84 pid_t tgid; /* thread group process ID */
85 spinlock_t lock;
86 struct key *session_keyring; /* keyring inherited over fork */
87 struct key *process_keyring; /* keyring private to this process */
88 struct rcu_head rcu; /* RCU deletion hook */
89};
90#endif
91
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92/*
93 * The security context of a task
94 *
95 * The parts of the context break down into two categories:
96 *
97 * (1) The objective context of a task. These parts are used when some other
98 * task is attempting to affect this one.
99 *
100 * (2) The subjective context. These details are used when the task is acting
101 * upon another object, be that a file, a task, a key or whatever.
102 *
103 * Note that some members of this structure belong to both categories - the
104 * LSM security pointer for instance.
105 *
106 * A task has two security pointers. task->real_cred points to the objective
107 * context that defines that task's actual details. The objective part of this
108 * context is used whenever that task is acted upon.
109 *
110 * task->cred points to the subjective context that defines the details of how
111 * that task is going to act upon another object. This may be overridden
112 * temporarily to point to another security context, but normally points to the
113 * same context as task->real_cred.
114 */
115struct cred {
116 atomic_t usage;
117 uid_t uid; /* real UID of the task */
118 gid_t gid; /* real GID of the task */
119 uid_t suid; /* saved UID of the task */
120 gid_t sgid; /* saved GID of the task */
121 uid_t euid; /* effective UID of the task */
122 gid_t egid; /* effective GID of the task */
123 uid_t fsuid; /* UID for VFS ops */
124 gid_t fsgid; /* GID for VFS ops */
125 unsigned securebits; /* SUID-less security management */
126 kernel_cap_t cap_inheritable; /* caps our children can inherit */
127 kernel_cap_t cap_permitted; /* caps we're permitted */
128 kernel_cap_t cap_effective; /* caps we can actually use */
129 kernel_cap_t cap_bset; /* capability bounding set */
130#ifdef CONFIG_KEYS
131 unsigned char jit_keyring; /* default keyring to attach requested
132 * keys to */
133 struct key *thread_keyring; /* keyring private to this thread */
134 struct key *request_key_auth; /* assumed request_key authority */
bb952bb9 135 struct thread_group_cred *tgcred; /* thread-group shared credentials */
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136#endif
137#ifdef CONFIG_SECURITY
138 void *security; /* subjective LSM security */
139#endif
140 struct user_struct *user; /* real user ID subscription */
141 struct group_info *group_info; /* supplementary groups for euid/fsgid */
142 struct rcu_head rcu; /* RCU deletion hook */
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143};
144
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145extern void __put_cred(struct cred *);
146extern int copy_creds(struct task_struct *, unsigned long);
d84f4f99 147extern struct cred *prepare_creds(void);
a6f76f23 148extern struct cred *prepare_exec_creds(void);
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149extern struct cred *prepare_usermodehelper_creds(void);
150extern int commit_creds(struct cred *);
151extern void abort_creds(struct cred *);
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152extern const struct cred *override_creds(const struct cred *);
153extern void revert_creds(const struct cred *);
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154extern struct cred *prepare_kernel_cred(struct task_struct *);
155extern int change_create_files_as(struct cred *, struct inode *);
156extern int set_security_override(struct cred *, u32);
157extern int set_security_override_from_ctx(struct cred *, const char *);
158extern int set_create_files_as(struct cred *, struct inode *);
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159extern void __init cred_init(void);
160
161/**
162 * get_new_cred - Get a reference on a new set of credentials
163 * @cred: The new credentials to reference
164 *
165 * Get a reference on the specified set of new credentials. The caller must
166 * release the reference.
167 */
168static inline struct cred *get_new_cred(struct cred *cred)
169{
170 atomic_inc(&cred->usage);
171 return cred;
172}
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173
174/**
175 * get_cred - Get a reference on a set of credentials
176 * @cred: The credentials to reference
177 *
178 * Get a reference on the specified set of credentials. The caller must
179 * release the reference.
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180 *
181 * This is used to deal with a committed set of credentials. Although the
182 * pointer is const, this will temporarily discard the const and increment the
183 * usage count. The purpose of this is to attempt to catch at compile time the
184 * accidental alteration of a set of credentials that should be considered
185 * immutable.
f1752eec 186 */
d84f4f99 187static inline const struct cred *get_cred(const struct cred *cred)
f1752eec 188{
d84f4f99 189 return get_new_cred((struct cred *) cred);
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190}
191
192/**
193 * put_cred - Release a reference to a set of credentials
194 * @cred: The credentials to release
195 *
196 * Release a reference to a set of credentials, deleting them when the last ref
197 * is released.
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198 *
199 * This takes a const pointer to a set of credentials because the credentials
200 * on task_struct are attached by const pointers to prevent accidental
201 * alteration of otherwise immutable credential sets.
f1752eec 202 */
c69e8d9c 203static inline void put_cred(const struct cred *_cred)
f1752eec 204{
c69e8d9c 205 struct cred *cred = (struct cred *) _cred;
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206
207 BUG_ON(atomic_read(&(cred)->usage) <= 0);
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208 if (atomic_dec_and_test(&(cred)->usage))
209 __put_cred(cred);
210}
211
86a264ab 212/**
3b11a1de 213 * current_cred - Access the current task's subjective credentials
86a264ab 214 *
3b11a1de 215 * Access the subjective credentials of the current task.
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216 */
217#define current_cred() \
218 (current->cred)
219
220/**
3b11a1de 221 * __task_cred - Access a task's objective credentials
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222 * @task: The task to query
223 *
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224 * Access the objective credentials of a task. The caller must hold the RCU
225 * readlock.
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226 *
227 * The caller must make sure task doesn't go away, either by holding a ref on
228 * task or by holding tasklist_lock to prevent it from being unlinked.
229 */
230#define __task_cred(task) \
3b11a1de 231 ((const struct cred *)(rcu_dereference((task)->real_cred)))
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232
233/**
3b11a1de 234 * get_task_cred - Get another task's objective credentials
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235 * @task: The task to query
236 *
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237 * Get the objective credentials of a task, pinning them so that they can't go
238 * away. Accessing a task's credentials directly is not permitted.
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239 *
240 * The caller must make sure task doesn't go away, either by holding a ref on
241 * task or by holding tasklist_lock to prevent it from being unlinked.
242 */
243#define get_task_cred(task) \
244({ \
245 struct cred *__cred; \
246 rcu_read_lock(); \
247 __cred = (struct cred *) __task_cred((task)); \
248 get_cred(__cred); \
249 rcu_read_unlock(); \
250 __cred; \
251})
252
253/**
3b11a1de 254 * get_current_cred - Get the current task's subjective credentials
86a264ab 255 *
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256 * Get the subjective credentials of the current task, pinning them so that
257 * they can't go away. Accessing the current task's credentials directly is
258 * not permitted.
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259 */
260#define get_current_cred() \
261 (get_cred(current_cred()))
262
263/**
264 * get_current_user - Get the current task's user_struct
265 *
266 * Get the user record of the current task, pinning it so that it can't go
267 * away.
268 */
269#define get_current_user() \
270({ \
271 struct user_struct *__u; \
272 struct cred *__cred; \
273 __cred = (struct cred *) current_cred(); \
274 __u = get_uid(__cred->user); \
275 __u; \
276})
277
278/**
279 * get_current_groups - Get the current task's supplementary group list
280 *
281 * Get the supplementary group list of the current task, pinning it so that it
282 * can't go away.
283 */
284#define get_current_groups() \
285({ \
286 struct group_info *__groups; \
287 struct cred *__cred; \
288 __cred = (struct cred *) current_cred(); \
289 __groups = get_group_info(__cred->group_info); \
290 __groups; \
291})
292
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293#define task_cred_xxx(task, xxx) \
294({ \
295 __typeof__(((struct cred *)NULL)->xxx) ___val; \
296 rcu_read_lock(); \
297 ___val = __task_cred((task))->xxx; \
298 rcu_read_unlock(); \
299 ___val; \
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300})
301
302#define task_uid(task) (task_cred_xxx((task), uid))
303#define task_euid(task) (task_cred_xxx((task), euid))
304
305#define current_cred_xxx(xxx) \
306({ \
307 current->cred->xxx; \
308})
309
310#define current_uid() (current_cred_xxx(uid))
311#define current_gid() (current_cred_xxx(gid))
312#define current_euid() (current_cred_xxx(euid))
313#define current_egid() (current_cred_xxx(egid))
314#define current_suid() (current_cred_xxx(suid))
315#define current_sgid() (current_cred_xxx(sgid))
316#define current_fsuid() (current_cred_xxx(fsuid))
317#define current_fsgid() (current_cred_xxx(fsgid))
318#define current_cap() (current_cred_xxx(cap_effective))
319#define current_user() (current_cred_xxx(user))
18b6e041 320#define current_user_ns() (current_cred_xxx(user)->user_ns)
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321#define current_security() (current_cred_xxx(security))
322
323#define current_uid_gid(_uid, _gid) \
324do { \
325 const struct cred *__cred; \
326 __cred = current_cred(); \
327 *(_uid) = __cred->uid; \
328 *(_gid) = __cred->gid; \
329} while(0)
330
331#define current_euid_egid(_euid, _egid) \
332do { \
333 const struct cred *__cred; \
334 __cred = current_cred(); \
335 *(_euid) = __cred->euid; \
336 *(_egid) = __cred->egid; \
337} while(0)
338
339#define current_fsuid_fsgid(_fsuid, _fsgid) \
340do { \
341 const struct cred *__cred; \
342 __cred = current_cred(); \
343 *(_fsuid) = __cred->fsuid; \
344 *(_fsgid) = __cred->fsgid; \
345} while(0)
346
9e2b2dc4 347#endif /* _LINUX_CRED_H */