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>
24 * COW Supplementary groups list
26 #define NGROUPS_SMALL 32
27 #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t)))
33 gid_t small_block[NGROUPS_SMALL];
38 * get_group_info - Get a reference to a group info structure
39 * @group_info: The group info to reference
41 * This gets a reference to a set of supplementary groups.
43 * If the caller is accessing a task's credentials, they must hold the RCU read
46 static inline struct group_info *get_group_info(struct group_info *gi)
48 atomic_inc(&gi->usage);
53 * put_group_info - Release a reference to a group info structure
54 * @group_info: The group info to release
56 #define put_group_info(group_info) \
58 if (atomic_dec_and_test(&(group_info)->usage)) \
59 groups_free(group_info); \
62 extern struct group_info *groups_alloc(int);
63 extern void groups_free(struct group_info *);
64 extern int set_current_groups(struct group_info *);
65 extern int set_groups(struct cred *, struct group_info *);
66 extern int groups_search(const struct group_info *, gid_t);
68 /* access the groups "array" with this macro */
69 #define GROUP_AT(gi, i) \
70 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
72 extern int in_group_p(gid_t);
73 extern int in_egroup_p(gid_t);
76 * The common credentials for a thread group
77 * - shared by CLONE_THREAD
80 struct thread_group_cred {
82 pid_t tgid; /* thread group process ID */
84 struct key *session_keyring; /* keyring inherited over fork */
85 struct key *process_keyring; /* keyring private to this process */
86 struct rcu_head rcu; /* RCU deletion hook */
91 * The security context of a task
93 * The parts of the context break down into two categories:
95 * (1) The objective context of a task. These parts are used when some other
96 * task is attempting to affect this one.
98 * (2) The subjective context. These details are used when the task is acting
99 * upon another object, be that a file, a task, a key or whatever.
101 * Note that some members of this structure belong to both categories - the
102 * LSM security pointer for instance.
104 * A task has two security pointers. task->real_cred points to the objective
105 * context that defines that task's actual details. The objective part of this
106 * context is used whenever that task is acted upon.
108 * task->cred points to the subjective context that defines the details of how
109 * that task is going to act upon another object. This may be overridden
110 * temporarily to point to another security context, but normally points to the
111 * same context as task->real_cred.
115 uid_t uid; /* real UID of the task */
116 gid_t gid; /* real GID of the task */
117 uid_t suid; /* saved UID of the task */
118 gid_t sgid; /* saved GID of the task */
119 uid_t euid; /* effective UID of the task */
120 gid_t egid; /* effective GID of the task */
121 uid_t fsuid; /* UID for VFS ops */
122 gid_t fsgid; /* GID for VFS ops */
123 unsigned securebits; /* SUID-less security management */
124 kernel_cap_t cap_inheritable; /* caps our children can inherit */
125 kernel_cap_t cap_permitted; /* caps we're permitted */
126 kernel_cap_t cap_effective; /* caps we can actually use */
127 kernel_cap_t cap_bset; /* capability bounding set */
129 unsigned char jit_keyring; /* default keyring to attach requested
131 struct key *thread_keyring; /* keyring private to this thread */
132 struct key *request_key_auth; /* assumed request_key authority */
133 struct thread_group_cred *tgcred; /* thread-group shared credentials */
135 #ifdef CONFIG_SECURITY
136 void *security; /* subjective LSM security */
138 struct user_struct *user; /* real user ID subscription */
139 struct group_info *group_info; /* supplementary groups for euid/fsgid */
140 struct rcu_head rcu; /* RCU deletion hook */
143 extern void __put_cred(struct cred *);
144 extern int copy_creds(struct task_struct *, unsigned long);
145 extern struct cred *prepare_creds(void);
146 extern struct cred *prepare_exec_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 *);
151 extern void revert_creds(const struct cred *);
152 extern struct cred *prepare_kernel_cred(struct task_struct *);
153 extern int change_create_files_as(struct cred *, struct inode *);
154 extern int set_security_override(struct cred *, u32);
155 extern int set_security_override_from_ctx(struct cred *, const char *);
156 extern int set_create_files_as(struct cred *, struct inode *);
157 extern void __init cred_init(void);
160 * get_new_cred - Get a reference on a new set of credentials
161 * @cred: The new credentials to reference
163 * Get a reference on the specified set of new credentials. The caller must
164 * release the reference.
166 static inline struct cred *get_new_cred(struct cred *cred)
168 atomic_inc(&cred->usage);
173 * get_cred - Get a reference on a set of credentials
174 * @cred: The credentials to reference
176 * Get a reference on the specified set of credentials. The caller must
177 * release the reference.
179 * This is used to deal with a committed set of credentials. Although the
180 * pointer is const, this will temporarily discard the const and increment the
181 * usage count. The purpose of this is to attempt to catch at compile time the
182 * accidental alteration of a set of credentials that should be considered
185 static inline const struct cred *get_cred(const struct cred *cred)
187 return get_new_cred((struct cred *) cred);
191 * put_cred - Release a reference to a set of credentials
192 * @cred: The credentials to release
194 * Release a reference to a set of credentials, deleting them when the last ref
197 * This takes a const pointer to a set of credentials because the credentials
198 * on task_struct are attached by const pointers to prevent accidental
199 * alteration of otherwise immutable credential sets.
201 static inline void put_cred(const struct cred *_cred)
203 struct cred *cred = (struct cred *) _cred;
205 BUG_ON(atomic_read(&(cred)->usage) <= 0);
206 if (atomic_dec_and_test(&(cred)->usage))
211 * current_cred - Access the current task's subjective credentials
213 * Access the subjective credentials of the current task.
215 #define current_cred() \
219 * __task_cred - Access a task's objective credentials
220 * @task: The task to query
222 * Access the objective credentials of a task. The caller must hold the RCU
225 * The caller must make sure task doesn't go away, either by holding a ref on
226 * task or by holding tasklist_lock to prevent it from being unlinked.
228 #define __task_cred(task) \
229 ((const struct cred *)(rcu_dereference((task)->real_cred)))
232 * get_task_cred - Get another task's objective credentials
233 * @task: The task to query
235 * Get the objective credentials of a task, pinning them so that they can't go
236 * away. Accessing a task's credentials directly is not permitted.
238 * The caller must make sure task doesn't go away, either by holding a ref on
239 * task or by holding tasklist_lock to prevent it from being unlinked.
241 #define get_task_cred(task) \
243 struct cred *__cred; \
245 __cred = (struct cred *) __task_cred((task)); \
252 * get_current_cred - Get the current task's subjective credentials
254 * Get the subjective credentials of the current task, pinning them so that
255 * they can't go away. Accessing the current task's credentials directly is
258 #define get_current_cred() \
259 (get_cred(current_cred()))
262 * get_current_user - Get the current task's user_struct
264 * Get the user record of the current task, pinning it so that it can't go
267 #define get_current_user() \
269 struct user_struct *__u; \
270 struct cred *__cred; \
271 __cred = (struct cred *) current_cred(); \
272 __u = get_uid(__cred->user); \
277 * get_current_groups - Get the current task's supplementary group list
279 * Get the supplementary group list of the current task, pinning it so that it
282 #define get_current_groups() \
284 struct group_info *__groups; \
285 struct cred *__cred; \
286 __cred = (struct cred *) current_cred(); \
287 __groups = get_group_info(__cred->group_info); \
291 #define task_cred_xxx(task, xxx) \
293 __typeof__(((struct cred *)NULL)->xxx) ___val; \
295 ___val = __task_cred((task))->xxx; \
300 #define task_uid(task) (task_cred_xxx((task), uid))
301 #define task_euid(task) (task_cred_xxx((task), euid))
303 #define current_cred_xxx(xxx) \
305 current->cred->xxx; \
308 #define current_uid() (current_cred_xxx(uid))
309 #define current_gid() (current_cred_xxx(gid))
310 #define current_euid() (current_cred_xxx(euid))
311 #define current_egid() (current_cred_xxx(egid))
312 #define current_suid() (current_cred_xxx(suid))
313 #define current_sgid() (current_cred_xxx(sgid))
314 #define current_fsuid() (current_cred_xxx(fsuid))
315 #define current_fsgid() (current_cred_xxx(fsgid))
316 #define current_cap() (current_cred_xxx(cap_effective))
317 #define current_user() (current_cred_xxx(user))
318 #define current_security() (current_cred_xxx(security))
320 #define current_uid_gid(_uid, _gid) \
322 const struct cred *__cred; \
323 __cred = current_cred(); \
324 *(_uid) = __cred->uid; \
325 *(_gid) = __cred->gid; \
328 #define current_euid_egid(_euid, _egid) \
330 const struct cred *__cred; \
331 __cred = current_cred(); \
332 *(_euid) = __cred->euid; \
333 *(_egid) = __cred->egid; \
336 #define current_fsuid_fsgid(_fsuid, _fsgid) \
338 const struct cred *__cred; \
339 __cred = current_cred(); \
340 *(_fsuid) = __cred->fsuid; \
341 *(_fsgid) = __cred->fsgid; \
344 #endif /* _LINUX_CRED_H */