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 common credentials for a thread group
76 * - shared by CLONE_THREAD
79 struct thread_group_cred {
81 pid_t tgid; /* thread group process ID */
83 struct key *session_keyring; /* keyring inherited over fork */
84 struct key *process_keyring; /* keyring private to this process */
85 struct rcu_head rcu; /* RCU deletion hook */
88 extern void release_tgcred(struct cred *cred);
92 * The security context of a task
94 * The parts of the context break down into two categories:
96 * (1) The objective context of a task. These parts are used when some other
97 * task is attempting to affect this one.
99 * (2) The subjective context. These details are used when the task is acting
100 * upon another object, be that a file, a task, a key or whatever.
102 * Note that some members of this structure belong to both categories - the
103 * LSM security pointer for instance.
105 * A task has two security pointers. task->real_cred points to the objective
106 * context that defines that task's actual details. The objective part of this
107 * context is used whenever that task is acted upon.
109 * task->cred points to the subjective context that defines the details of how
110 * that task is going to act upon another object. This may be overridden
111 * temporarily to point to another security context, but normally points to the
112 * same context as task->real_cred.
116 uid_t uid; /* real UID of the task */
117 gid_t gid; /* real GID of the task */
118 uid_t suid; /* saved UID of the task */
119 gid_t sgid; /* saved GID of the task */
120 uid_t euid; /* effective UID of the task */
121 gid_t egid; /* effective GID of the task */
122 uid_t fsuid; /* UID for VFS ops */
123 gid_t fsgid; /* GID for VFS ops */
124 unsigned securebits; /* SUID-less security management */
125 kernel_cap_t cap_inheritable; /* caps our children can inherit */
126 kernel_cap_t cap_permitted; /* caps we're permitted */
127 kernel_cap_t cap_effective; /* caps we can actually use */
128 kernel_cap_t cap_bset; /* capability bounding set */
130 unsigned char jit_keyring; /* default keyring to attach requested
132 struct key *thread_keyring; /* keyring private to this thread */
133 struct key *request_key_auth; /* assumed request_key authority */
134 struct thread_group_cred *tgcred; /* thread-group shared credentials */
136 #ifdef CONFIG_SECURITY
137 void *security; /* subjective LSM security */
139 struct user_struct *user; /* real user ID subscription */
140 struct group_info *group_info; /* supplementary groups for euid/fsgid */
141 struct rcu_head rcu; /* RCU deletion hook */
144 extern void __put_cred(struct cred *);
145 extern int copy_creds(struct task_struct *, unsigned long);
146 extern struct cred *prepare_creds(void);
147 extern struct cred *prepare_usermodehelper_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 *) __deprecated;
151 extern void revert_creds(const struct cred *) __deprecated;
152 extern void __init cred_init(void);
155 * get_new_cred - Get a reference on a new set of credentials
156 * @cred: The new credentials to reference
158 * Get a reference on the specified set of new credentials. The caller must
159 * release the reference.
161 static inline struct cred *get_new_cred(struct cred *cred)
163 atomic_inc(&cred->usage);
168 * get_cred - Get a reference on a set of credentials
169 * @cred: The credentials to reference
171 * Get a reference on the specified set of credentials. The caller must
172 * release the reference.
174 static inline const struct cred *get_cred(const struct cred *cred)
176 return get_new_cred((struct cred *) cred);
180 * put_cred - Release a reference to a set of credentials
181 * @cred: The credentials to release
183 * Release a reference to a set of credentials, deleting them when the last ref
186 static inline void put_cred(const struct cred *_cred)
188 struct cred *cred = (struct cred *) _cred;
190 BUG_ON(atomic_read(&(cred)->usage) <= 0);
191 if (atomic_dec_and_test(&(cred)->usage))
196 * current_cred - Access the current task's credentials
198 * Access the credentials of the current task.
200 #define current_cred() \
204 * __task_cred - Access another task's credentials
205 * @task: The task to query
207 * Access the credentials of another task. The caller must hold the
210 * The caller must make sure task doesn't go away, either by holding a ref on
211 * task or by holding tasklist_lock to prevent it from being unlinked.
213 #define __task_cred(task) \
214 ((const struct cred *)(rcu_dereference((task)->cred)))
217 * get_task_cred - Get another task's credentials
218 * @task: The task to query
220 * Get the credentials of a task, pinning them so that they can't go away.
221 * Accessing a task's credentials directly is not permitted.
223 * The caller must make sure task doesn't go away, either by holding a ref on
224 * task or by holding tasklist_lock to prevent it from being unlinked.
226 #define get_task_cred(task) \
228 struct cred *__cred; \
230 __cred = (struct cred *) __task_cred((task)); \
237 * get_current_cred - Get the current task's credentials
239 * Get the credentials of the current task, pinning them so that they can't go
240 * away. Accessing the current task's credentials directly is not permitted.
242 #define get_current_cred() \
243 (get_cred(current_cred()))
246 * get_current_user - Get the current task's user_struct
248 * Get the user record of the current task, pinning it so that it can't go
251 #define get_current_user() \
253 struct user_struct *__u; \
254 struct cred *__cred; \
255 __cred = (struct cred *) current_cred(); \
256 __u = get_uid(__cred->user); \
261 * get_current_groups - Get the current task's supplementary group list
263 * Get the supplementary group list of the current task, pinning it so that it
266 #define get_current_groups() \
268 struct group_info *__groups; \
269 struct cred *__cred; \
270 __cred = (struct cred *) current_cred(); \
271 __groups = get_group_info(__cred->group_info); \
275 #define task_cred_xxx(task, xxx) \
277 __typeof__(((struct cred *)NULL)->xxx) ___val; \
279 ___val = __task_cred((task))->xxx; \
284 #define task_uid(task) (task_cred_xxx((task), uid))
285 #define task_euid(task) (task_cred_xxx((task), euid))
287 #define current_cred_xxx(xxx) \
289 current->cred->xxx; \
292 #define current_uid() (current_cred_xxx(uid))
293 #define current_gid() (current_cred_xxx(gid))
294 #define current_euid() (current_cred_xxx(euid))
295 #define current_egid() (current_cred_xxx(egid))
296 #define current_suid() (current_cred_xxx(suid))
297 #define current_sgid() (current_cred_xxx(sgid))
298 #define current_fsuid() (current_cred_xxx(fsuid))
299 #define current_fsgid() (current_cred_xxx(fsgid))
300 #define current_cap() (current_cred_xxx(cap_effective))
301 #define current_user() (current_cred_xxx(user))
302 #define current_security() (current_cred_xxx(security))
304 #define current_uid_gid(_uid, _gid) \
306 const struct cred *__cred; \
307 __cred = current_cred(); \
308 *(_uid) = __cred->uid; \
309 *(_gid) = __cred->gid; \
312 #define current_euid_egid(_euid, _egid) \
314 const struct cred *__cred; \
315 __cred = current_cred(); \
316 *(_euid) = __cred->euid; \
317 *(_egid) = __cred->egid; \
320 #define current_fsuid_fsgid(_fsuid, _fsgid) \
322 const struct cred *__cred; \
323 __cred = current_cred(); \
324 *(_fsuid) = __cred->fsuid; \
325 *(_fsgid) = __cred->fsgid; \
328 #endif /* _LINUX_CRED_H */