1 /* Credentials management
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
15 #include <linux/capability.h>
16 #include <linux/key.h>
17 #include <asm/atomic.h>
23 * COW Supplementary groups list
25 #define NGROUPS_SMALL 32
26 #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t)))
32 gid_t small_block
[NGROUPS_SMALL
];
37 * get_group_info - Get a reference to a group info structure
38 * @group_info: The group info to reference
40 * This gets a reference to a set of supplementary groups.
42 * If the caller is accessing a task's credentials, they must hold the RCU read
45 static inline struct group_info
*get_group_info(struct group_info
*gi
)
47 atomic_inc(&gi
->usage
);
52 * put_group_info - Release a reference to a group info structure
53 * @group_info: The group info to release
55 #define put_group_info(group_info) \
57 if (atomic_dec_and_test(&(group_info)->usage)) \
58 groups_free(group_info); \
61 extern struct group_info
*groups_alloc(int);
62 extern void groups_free(struct group_info
*);
63 extern int set_current_groups(struct group_info
*);
64 extern int set_groups(struct cred
*, struct group_info
*);
65 extern int groups_search(const struct group_info
*, gid_t
);
67 /* access the groups "array" with this macro */
68 #define GROUP_AT(gi, i) \
69 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
71 extern int in_group_p(gid_t
);
72 extern int in_egroup_p(gid_t
);
75 * The security context of a task
77 * The parts of the context break down into two categories:
79 * (1) The objective context of a task. These parts are used when some other
80 * task is attempting to affect this one.
82 * (2) The subjective context. These details are used when the task is acting
83 * upon another object, be that a file, a task, a key or whatever.
85 * Note that some members of this structure belong to both categories - the
86 * LSM security pointer for instance.
88 * A task has two security pointers. task->real_cred points to the objective
89 * context that defines that task's actual details. The objective part of this
90 * context is used whenever that task is acted upon.
92 * task->cred points to the subjective context that defines the details of how
93 * that task is going to act upon another object. This may be overridden
94 * temporarily to point to another security context, but normally points to the
95 * same context as task->real_cred.
99 uid_t uid
; /* real UID of the task */
100 gid_t gid
; /* real GID of the task */
101 uid_t suid
; /* saved UID of the task */
102 gid_t sgid
; /* saved GID of the task */
103 uid_t euid
; /* effective UID of the task */
104 gid_t egid
; /* effective GID of the task */
105 uid_t fsuid
; /* UID for VFS ops */
106 gid_t fsgid
; /* GID for VFS ops */
107 unsigned securebits
; /* SUID-less security management */
108 kernel_cap_t cap_inheritable
; /* caps our children can inherit */
109 kernel_cap_t cap_permitted
; /* caps we're permitted */
110 kernel_cap_t cap_effective
; /* caps we can actually use */
111 kernel_cap_t cap_bset
; /* capability bounding set */
113 unsigned char jit_keyring
; /* default keyring to attach requested
115 struct key
*thread_keyring
; /* keyring private to this thread */
116 struct key
*request_key_auth
; /* assumed request_key authority */
118 #ifdef CONFIG_SECURITY
119 void *security
; /* subjective LSM security */
121 struct user_struct
*user
; /* real user ID subscription */
122 struct group_info
*group_info
; /* supplementary groups for euid/fsgid */
123 struct rcu_head rcu
; /* RCU deletion hook */
124 spinlock_t lock
; /* lock for pointer changes */
127 extern void __put_cred(struct cred
*);
128 extern int copy_creds(struct task_struct
*, unsigned long);
131 * get_cred - Get a reference on a set of credentials
132 * @cred: The credentials to reference
134 * Get a reference on the specified set of credentials. The caller must
135 * release the reference.
137 static inline struct cred
*get_cred(struct cred
*cred
)
139 atomic_inc(&cred
->usage
);
144 * put_cred - Release a reference to a set of credentials
145 * @cred: The credentials to release
147 * Release a reference to a set of credentials, deleting them when the last ref
150 static inline void put_cred(struct cred
*cred
)
152 if (atomic_dec_and_test(&(cred
)->usage
))
157 * current_cred - Access the current task's credentials
159 * Access the credentials of the current task.
161 #define current_cred() \
165 * __task_cred - Access another task's credentials
166 * @task: The task to query
168 * Access the credentials of another task. The caller must hold the
171 * The caller must make sure task doesn't go away, either by holding a ref on
172 * task or by holding tasklist_lock to prevent it from being unlinked.
174 #define __task_cred(task) \
175 ((const struct cred *)(rcu_dereference((task)->cred)))
178 * get_task_cred - Get another task's credentials
179 * @task: The task to query
181 * Get the credentials of a task, pinning them so that they can't go away.
182 * Accessing a task's credentials directly is not permitted.
184 * The caller must make sure task doesn't go away, either by holding a ref on
185 * task or by holding tasklist_lock to prevent it from being unlinked.
187 #define get_task_cred(task) \
189 struct cred *__cred; \
191 __cred = (struct cred *) __task_cred((task)); \
198 * get_current_cred - Get the current task's credentials
200 * Get the credentials of the current task, pinning them so that they can't go
201 * away. Accessing the current task's credentials directly is not permitted.
203 #define get_current_cred() \
204 (get_cred(current_cred()))
207 * get_current_user - Get the current task's user_struct
209 * Get the user record of the current task, pinning it so that it can't go
212 #define get_current_user() \
214 struct user_struct *__u; \
215 struct cred *__cred; \
216 __cred = (struct cred *) current_cred(); \
217 __u = get_uid(__cred->user); \
222 * get_current_groups - Get the current task's supplementary group list
224 * Get the supplementary group list of the current task, pinning it so that it
227 #define get_current_groups() \
229 struct group_info *__groups; \
230 struct cred *__cred; \
231 __cred = (struct cred *) current_cred(); \
232 __groups = get_group_info(__cred->group_info); \
236 #define task_cred_xxx(task, xxx) \
238 __typeof__(task->cred->xxx) ___val; \
240 ___val = __task_cred((task))->xxx; \
245 #define task_uid(task) (task_cred_xxx((task), uid))
246 #define task_euid(task) (task_cred_xxx((task), euid))
248 #define current_cred_xxx(xxx) \
250 current->cred->xxx; \
253 #define current_uid() (current_cred_xxx(uid))
254 #define current_gid() (current_cred_xxx(gid))
255 #define current_euid() (current_cred_xxx(euid))
256 #define current_egid() (current_cred_xxx(egid))
257 #define current_suid() (current_cred_xxx(suid))
258 #define current_sgid() (current_cred_xxx(sgid))
259 #define current_fsuid() (current_cred_xxx(fsuid))
260 #define current_fsgid() (current_cred_xxx(fsgid))
261 #define current_cap() (current_cred_xxx(cap_effective))
262 #define current_user() (current_cred_xxx(user))
263 #define current_security() (current_cred_xxx(security))
265 #define current_uid_gid(_uid, _gid) \
267 const struct cred *__cred; \
268 __cred = current_cred(); \
269 *(_uid) = __cred->uid; \
270 *(_gid) = __cred->gid; \
273 #define current_euid_egid(_euid, _egid) \
275 const struct cred *__cred; \
276 __cred = current_cred(); \
277 *(_euid) = __cred->euid; \
278 *(_egid) = __cred->egid; \
281 #define current_fsuid_fsgid(_fsuid, _fsgid) \
283 const struct cred *__cred; \
284 __cred = current_cred(); \
285 *(_fsuid) = __cred->fsuid; \
286 *(_fsgid) = __cred->fsgid; \
289 #endif /* _LINUX_CRED_H */