1 /* Credentials management - see Documentation/security/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/init.h>
17 #include <linux/key.h>
18 #include <linux/selinux.h>
19 #include <linux/atomic.h>
20 #include <linux/uidgid.h>
27 * COW Supplementary groups list
29 #define NGROUPS_SMALL 32
30 #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t)))
36 kgid_t small_block
[NGROUPS_SMALL
];
41 * get_group_info - Get a reference to a group info structure
42 * @group_info: The group info to reference
44 * This gets a reference to a set of supplementary groups.
46 * If the caller is accessing a task's credentials, they must hold the RCU read
49 static inline struct group_info
*get_group_info(struct group_info
*gi
)
51 atomic_inc(&gi
->usage
);
56 * put_group_info - Release a reference to a group info structure
57 * @group_info: The group info to release
59 #define put_group_info(group_info) \
61 if (atomic_dec_and_test(&(group_info)->usage)) \
62 groups_free(group_info); \
65 extern struct group_info
*groups_alloc(int);
66 extern struct group_info init_groups
;
67 extern void groups_free(struct group_info
*);
68 extern int set_current_groups(struct group_info
*);
69 extern int set_groups(struct cred
*, struct group_info
*);
70 extern int groups_search(const struct group_info
*, kgid_t
);
72 /* access the groups "array" with this macro */
73 #define GROUP_AT(gi, i) \
74 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
76 extern int in_group_p(kgid_t
);
77 extern int in_egroup_p(kgid_t
);
80 * The security context of a task
82 * The parts of the context break down into two categories:
84 * (1) The objective context of a task. These parts are used when some other
85 * task is attempting to affect this one.
87 * (2) The subjective context. These details are used when the task is acting
88 * upon another object, be that a file, a task, a key or whatever.
90 * Note that some members of this structure belong to both categories - the
91 * LSM security pointer for instance.
93 * A task has two security pointers. task->real_cred points to the objective
94 * context that defines that task's actual details. The objective part of this
95 * context is used whenever that task is acted upon.
97 * task->cred points to the subjective context that defines the details of how
98 * that task is going to act upon another object. This may be overridden
99 * temporarily to point to another security context, but normally points to the
100 * same context as task->real_cred.
104 #ifdef CONFIG_DEBUG_CREDENTIALS
105 atomic_t subscribers
; /* number of processes subscribed */
108 #define CRED_MAGIC 0x43736564
109 #define CRED_MAGIC_DEAD 0x44656144
111 kuid_t uid
; /* real UID of the task */
112 kgid_t gid
; /* real GID of the task */
113 kuid_t suid
; /* saved UID of the task */
114 kgid_t sgid
; /* saved GID of the task */
115 kuid_t euid
; /* effective UID of the task */
116 kgid_t egid
; /* effective GID of the task */
117 kuid_t fsuid
; /* UID for VFS ops */
118 kgid_t fsgid
; /* GID for VFS ops */
119 unsigned securebits
; /* SUID-less security management */
120 kernel_cap_t cap_inheritable
; /* caps our children can inherit */
121 kernel_cap_t cap_permitted
; /* caps we're permitted */
122 kernel_cap_t cap_effective
; /* caps we can actually use */
123 kernel_cap_t cap_bset
; /* capability bounding set */
125 unsigned char jit_keyring
; /* default keyring to attach requested
127 struct key __rcu
*session_keyring
; /* keyring inherited over fork */
128 struct key
*process_keyring
; /* keyring private to this process */
129 struct key
*thread_keyring
; /* keyring private to this thread */
130 struct key
*request_key_auth
; /* assumed request_key authority */
132 #ifdef CONFIG_SECURITY
133 void *security
; /* subjective LSM security */
135 struct user_struct
*user
; /* real user ID subscription */
136 struct user_namespace
*user_ns
; /* user_ns the caps and keyrings are relative to. */
137 struct group_info
*group_info
; /* supplementary groups for euid/fsgid */
138 struct rcu_head rcu
; /* RCU deletion hook */
141 extern void __put_cred(struct cred
*);
142 extern void exit_creds(struct task_struct
*);
143 extern int copy_creds(struct task_struct
*, unsigned long);
144 extern const struct cred
*get_task_cred(struct task_struct
*);
145 extern struct cred
*cred_alloc_blank(void);
146 extern struct cred
*prepare_creds(void);
147 extern struct cred
*prepare_exec_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 * check for validity of credentials
162 #ifdef CONFIG_DEBUG_CREDENTIALS
163 extern void __invalid_creds(const struct cred
*, const char *, unsigned);
164 extern void __validate_process_creds(struct task_struct
*,
165 const char *, unsigned);
167 extern bool creds_are_invalid(const struct cred
*cred
);
169 static inline void __validate_creds(const struct cred
*cred
,
170 const char *file
, unsigned line
)
172 if (unlikely(creds_are_invalid(cred
)))
173 __invalid_creds(cred
, file
, line
);
176 #define validate_creds(cred) \
178 __validate_creds((cred), __FILE__, __LINE__); \
181 #define validate_process_creds() \
183 __validate_process_creds(current, __FILE__, __LINE__); \
186 extern void validate_creds_for_do_exit(struct task_struct
*);
188 static inline void validate_creds(const struct cred
*cred
)
191 static inline void validate_creds_for_do_exit(struct task_struct
*tsk
)
194 static inline void validate_process_creds(void)
200 * get_new_cred - Get a reference on a new set of credentials
201 * @cred: The new credentials to reference
203 * Get a reference on the specified set of new credentials. The caller must
204 * release the reference.
206 static inline struct cred
*get_new_cred(struct cred
*cred
)
208 atomic_inc(&cred
->usage
);
213 * get_cred - Get a reference on a set of credentials
214 * @cred: The credentials to reference
216 * Get a reference on the specified set of credentials. The caller must
217 * release the reference.
219 * This is used to deal with a committed set of credentials. Although the
220 * pointer is const, this will temporarily discard the const and increment the
221 * usage count. The purpose of this is to attempt to catch at compile time the
222 * accidental alteration of a set of credentials that should be considered
225 static inline const struct cred
*get_cred(const struct cred
*cred
)
227 struct cred
*nonconst_cred
= (struct cred
*) cred
;
228 validate_creds(cred
);
229 return get_new_cred(nonconst_cred
);
233 * put_cred - Release a reference to a set of credentials
234 * @cred: The credentials to release
236 * Release a reference to a set of credentials, deleting them when the last ref
239 * This takes a const pointer to a set of credentials because the credentials
240 * on task_struct are attached by const pointers to prevent accidental
241 * alteration of otherwise immutable credential sets.
243 static inline void put_cred(const struct cred
*_cred
)
245 struct cred
*cred
= (struct cred
*) _cred
;
247 validate_creds(cred
);
248 if (atomic_dec_and_test(&(cred
)->usage
))
253 * current_cred - Access the current task's subjective credentials
255 * Access the subjective credentials of the current task. RCU-safe,
256 * since nobody else can modify it.
258 #define current_cred() \
259 rcu_dereference_protected(current->cred, 1)
262 * __task_cred - Access a task's objective credentials
263 * @task: The task to query
265 * Access the objective credentials of a task. The caller must hold the RCU
268 * The result of this function should not be passed directly to get_cred();
269 * rather get_task_cred() should be used instead.
271 #define __task_cred(task) \
272 rcu_dereference((task)->real_cred)
275 * get_current_cred - Get the current task's subjective credentials
277 * Get the subjective credentials of the current task, pinning them so that
278 * they can't go away. Accessing the current task's credentials directly is
281 #define get_current_cred() \
282 (get_cred(current_cred()))
285 * get_current_user - Get the current task's user_struct
287 * Get the user record of the current task, pinning it so that it can't go
290 #define get_current_user() \
292 struct user_struct *__u; \
293 const struct cred *__cred; \
294 __cred = current_cred(); \
295 __u = get_uid(__cred->user); \
300 * get_current_groups - Get the current task's supplementary group list
302 * Get the supplementary group list of the current task, pinning it so that it
305 #define get_current_groups() \
307 struct group_info *__groups; \
308 const struct cred *__cred; \
309 __cred = current_cred(); \
310 __groups = get_group_info(__cred->group_info); \
314 #define task_cred_xxx(task, xxx) \
316 __typeof__(((struct cred *)NULL)->xxx) ___val; \
318 ___val = __task_cred((task))->xxx; \
323 #define task_uid(task) (task_cred_xxx((task), uid))
324 #define task_euid(task) (task_cred_xxx((task), euid))
326 #define current_cred_xxx(xxx) \
328 current_cred()->xxx; \
331 #define current_uid() (current_cred_xxx(uid))
332 #define current_gid() (current_cred_xxx(gid))
333 #define current_euid() (current_cred_xxx(euid))
334 #define current_egid() (current_cred_xxx(egid))
335 #define current_suid() (current_cred_xxx(suid))
336 #define current_sgid() (current_cred_xxx(sgid))
337 #define current_fsuid() (current_cred_xxx(fsuid))
338 #define current_fsgid() (current_cred_xxx(fsgid))
339 #define current_cap() (current_cred_xxx(cap_effective))
340 #define current_user() (current_cred_xxx(user))
341 #define current_security() (current_cred_xxx(security))
343 extern struct user_namespace init_user_ns
;
344 #ifdef CONFIG_USER_NS
345 #define current_user_ns() (current_cred_xxx(user_ns))
347 #define current_user_ns() (&init_user_ns)
351 #define current_uid_gid(_uid, _gid) \
353 const struct cred *__cred; \
354 __cred = current_cred(); \
355 *(_uid) = __cred->uid; \
356 *(_gid) = __cred->gid; \
359 #define current_euid_egid(_euid, _egid) \
361 const struct cred *__cred; \
362 __cred = current_cred(); \
363 *(_euid) = __cred->euid; \
364 *(_egid) = __cred->egid; \
367 #define current_fsuid_fsgid(_fsuid, _fsgid) \
369 const struct cred *__cred; \
370 __cred = current_cred(); \
371 *(_fsuid) = __cred->fsuid; \
372 *(_fsgid) = __cred->fsgid; \
375 #endif /* _LINUX_CRED_H */