1 /* Credentials management - see Documentation/credentials.txt
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 */
90 * The security context of a task
92 * The parts of the context break down into two categories:
94 * (1) The objective context of a task. These parts are used when some other
95 * task is attempting to affect this one.
97 * (2) The subjective context. These details are used when the task is acting
98 * upon another object, be that a file, a task, a key or whatever.
100 * Note that some members of this structure belong to both categories - the
101 * LSM security pointer for instance.
103 * A task has two security pointers. task->real_cred points to the objective
104 * context that defines that task's actual details. The objective part of this
105 * context is used whenever that task is acted upon.
107 * task->cred points to the subjective context that defines the details of how
108 * that task is going to act upon another object. This may be overridden
109 * temporarily to point to another security context, but normally points to the
110 * same context as task->real_cred.
114 uid_t uid; /* real UID of the task */
115 gid_t gid; /* real GID of the task */
116 uid_t suid; /* saved UID of the task */
117 gid_t sgid; /* saved GID of the task */
118 uid_t euid; /* effective UID of the task */
119 gid_t egid; /* effective GID of the task */
120 uid_t fsuid; /* UID for VFS ops */
121 gid_t fsgid; /* GID for VFS ops */
122 unsigned securebits; /* SUID-less security management */
123 kernel_cap_t cap_inheritable; /* caps our children can inherit */
124 kernel_cap_t cap_permitted; /* caps we're permitted */
125 kernel_cap_t cap_effective; /* caps we can actually use */
126 kernel_cap_t cap_bset; /* capability bounding set */
128 unsigned char jit_keyring; /* default keyring to attach requested
130 struct key *thread_keyring; /* keyring private to this thread */
131 struct key *request_key_auth; /* assumed request_key authority */
132 struct thread_group_cred *tgcred; /* thread-group shared credentials */
134 #ifdef CONFIG_SECURITY
135 void *security; /* subjective LSM security */
137 struct user_struct *user; /* real user ID subscription */
138 struct group_info *group_info; /* supplementary groups for euid/fsgid */
139 struct rcu_head rcu; /* RCU deletion hook */
142 extern void __put_cred(struct cred *);
143 extern int copy_creds(struct task_struct *, unsigned long);
144 extern struct cred *prepare_creds(void);
145 extern struct cred *prepare_exec_creds(void);
146 extern struct cred *prepare_usermodehelper_creds(void);
147 extern int commit_creds(struct cred *);
148 extern void abort_creds(struct cred *);
149 extern const struct cred *override_creds(const struct cred *) __deprecated;
150 extern void revert_creds(const struct cred *) __deprecated;
151 extern void __init cred_init(void);
154 * get_new_cred - Get a reference on a new set of credentials
155 * @cred: The new credentials to reference
157 * Get a reference on the specified set of new credentials. The caller must
158 * release the reference.
160 static inline struct cred *get_new_cred(struct cred *cred)
162 atomic_inc(&cred->usage);
167 * get_cred - Get a reference on a set of credentials
168 * @cred: The credentials to reference
170 * Get a reference on the specified set of credentials. The caller must
171 * release the reference.
173 * This is used to deal with a committed set of credentials. Although the
174 * pointer is const, this will temporarily discard the const and increment the
175 * usage count. The purpose of this is to attempt to catch at compile time the
176 * accidental alteration of a set of credentials that should be considered
179 static inline const struct cred *get_cred(const struct cred *cred)
181 return get_new_cred((struct cred *) cred);
185 * put_cred - Release a reference to a set of credentials
186 * @cred: The credentials to release
188 * Release a reference to a set of credentials, deleting them when the last ref
191 * This takes a const pointer to a set of credentials because the credentials
192 * on task_struct are attached by const pointers to prevent accidental
193 * alteration of otherwise immutable credential sets.
195 static inline void put_cred(const struct cred *_cred)
197 struct cred *cred = (struct cred *) _cred;
199 BUG_ON(atomic_read(&(cred)->usage) <= 0);
200 if (atomic_dec_and_test(&(cred)->usage))
205 * current_cred - Access the current task's credentials
207 * Access the credentials of the current task.
209 #define current_cred() \
213 * __task_cred - Access another task's credentials
214 * @task: The task to query
216 * Access the credentials of another task. The caller must hold the
219 * The caller must make sure task doesn't go away, either by holding a ref on
220 * task or by holding tasklist_lock to prevent it from being unlinked.
222 #define __task_cred(task) \
223 ((const struct cred *)(rcu_dereference((task)->cred)))
226 * get_task_cred - Get another task's credentials
227 * @task: The task to query
229 * Get the credentials of a task, pinning them so that they can't go away.
230 * Accessing a task's credentials directly is not permitted.
232 * The caller must make sure task doesn't go away, either by holding a ref on
233 * task or by holding tasklist_lock to prevent it from being unlinked.
235 #define get_task_cred(task) \
237 struct cred *__cred; \
239 __cred = (struct cred *) __task_cred((task)); \
246 * get_current_cred - Get the current task's credentials
248 * Get the credentials of the current task, pinning them so that they can't go
249 * away. Accessing the current task's credentials directly is not permitted.
251 #define get_current_cred() \
252 (get_cred(current_cred()))
255 * get_current_user - Get the current task's user_struct
257 * Get the user record of the current task, pinning it so that it can't go
260 #define get_current_user() \
262 struct user_struct *__u; \
263 struct cred *__cred; \
264 __cred = (struct cred *) current_cred(); \
265 __u = get_uid(__cred->user); \
270 * get_current_groups - Get the current task's supplementary group list
272 * Get the supplementary group list of the current task, pinning it so that it
275 #define get_current_groups() \
277 struct group_info *__groups; \
278 struct cred *__cred; \
279 __cred = (struct cred *) current_cred(); \
280 __groups = get_group_info(__cred->group_info); \
284 #define task_cred_xxx(task, xxx) \
286 __typeof__(((struct cred *)NULL)->xxx) ___val; \
288 ___val = __task_cred((task))->xxx; \
293 #define task_uid(task) (task_cred_xxx((task), uid))
294 #define task_euid(task) (task_cred_xxx((task), euid))
296 #define current_cred_xxx(xxx) \
298 current->cred->xxx; \
301 #define current_uid() (current_cred_xxx(uid))
302 #define current_gid() (current_cred_xxx(gid))
303 #define current_euid() (current_cred_xxx(euid))
304 #define current_egid() (current_cred_xxx(egid))
305 #define current_suid() (current_cred_xxx(suid))
306 #define current_sgid() (current_cred_xxx(sgid))
307 #define current_fsuid() (current_cred_xxx(fsuid))
308 #define current_fsgid() (current_cred_xxx(fsgid))
309 #define current_cap() (current_cred_xxx(cap_effective))
310 #define current_user() (current_cred_xxx(user))
311 #define current_security() (current_cred_xxx(security))
313 #define current_uid_gid(_uid, _gid) \
315 const struct cred *__cred; \
316 __cred = current_cred(); \
317 *(_uid) = __cred->uid; \
318 *(_gid) = __cred->gid; \
321 #define current_euid_egid(_euid, _egid) \
323 const struct cred *__cred; \
324 __cred = current_cred(); \
325 *(_euid) = __cred->euid; \
326 *(_egid) = __cred->egid; \
329 #define current_fsuid_fsgid(_fsuid, _fsgid) \
331 const struct cred *__cred; \
332 __cred = current_cred(); \
333 *(_fsuid) = __cred->fsuid; \
334 *(_fsgid) = __cred->fsgid; \
337 #endif /* _LINUX_CRED_H */