1 /* Credentials management - see Documentation/security/credentials.rst
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>
21 #include <linux/sched.h>
22 #include <linux/sched/user.h>
28 * COW Supplementary groups list
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 init_groups
;
62 #ifdef CONFIG_MULTIUSER
63 extern struct group_info
*groups_alloc(int);
64 extern void groups_free(struct group_info
*);
66 extern int in_group_p(kgid_t
);
67 extern int in_egroup_p(kgid_t
);
69 static inline void groups_free(struct group_info
*group_info
)
73 static inline int in_group_p(kgid_t grp
)
77 static inline int in_egroup_p(kgid_t grp
)
82 extern int set_current_groups(struct group_info
*);
83 extern void set_groups(struct cred
*, struct group_info
*);
84 extern int groups_search(const struct group_info
*, kgid_t
);
85 extern bool may_setgroups(void);
86 extern void groups_sort(struct group_info
*);
89 * The security context of a task
91 * The parts of the context break down into two categories:
93 * (1) The objective context of a task. These parts are used when some other
94 * task is attempting to affect this one.
96 * (2) The subjective context. These details are used when the task is acting
97 * upon another object, be that a file, a task, a key or whatever.
99 * Note that some members of this structure belong to both categories - the
100 * LSM security pointer for instance.
102 * A task has two security pointers. task->real_cred points to the objective
103 * context that defines that task's actual details. The objective part of this
104 * context is used whenever that task is acted upon.
106 * task->cred points to the subjective context that defines the details of how
107 * that task is going to act upon another object. This may be overridden
108 * temporarily to point to another security context, but normally points to the
109 * same context as task->real_cred.
113 #ifdef CONFIG_DEBUG_CREDENTIALS
114 atomic_t subscribers
; /* number of processes subscribed */
117 #define CRED_MAGIC 0x43736564
118 #define CRED_MAGIC_DEAD 0x44656144
120 kuid_t uid
; /* real UID of the task */
121 kgid_t gid
; /* real GID of the task */
122 kuid_t suid
; /* saved UID of the task */
123 kgid_t sgid
; /* saved GID of the task */
124 kuid_t euid
; /* effective UID of the task */
125 kgid_t egid
; /* effective GID of the task */
126 kuid_t fsuid
; /* UID for VFS ops */
127 kgid_t fsgid
; /* GID for VFS ops */
128 unsigned securebits
; /* SUID-less security management */
129 kernel_cap_t cap_inheritable
; /* caps our children can inherit */
130 kernel_cap_t cap_permitted
; /* caps we're permitted */
131 kernel_cap_t cap_effective
; /* caps we can actually use */
132 kernel_cap_t cap_bset
; /* capability bounding set */
133 kernel_cap_t cap_ambient
; /* Ambient capability set */
135 unsigned char jit_keyring
; /* default keyring to attach requested
137 struct key __rcu
*session_keyring
; /* keyring inherited over fork */
138 struct key
*process_keyring
; /* keyring private to this process */
139 struct key
*thread_keyring
; /* keyring private to this thread */
140 struct key
*request_key_auth
; /* assumed request_key authority */
142 #ifdef CONFIG_SECURITY
143 void *security
; /* subjective LSM security */
145 struct user_struct
*user
; /* real user ID subscription */
146 struct user_namespace
*user_ns
; /* user_ns the caps and keyrings are relative to. */
147 struct group_info
*group_info
; /* supplementary groups for euid/fsgid */
150 int non_rcu
; /* Can we skip RCU deletion? */
151 struct rcu_head rcu
; /* RCU deletion hook */
153 } __randomize_layout
;
155 extern void __put_cred(struct cred
*);
156 extern void exit_creds(struct task_struct
*);
157 extern int copy_creds(struct task_struct
*, unsigned long);
158 extern const struct cred
*get_task_cred(struct task_struct
*);
159 extern struct cred
*cred_alloc_blank(void);
160 extern struct cred
*prepare_creds(void);
161 extern struct cred
*prepare_exec_creds(void);
162 extern int commit_creds(struct cred
*);
163 extern void abort_creds(struct cred
*);
164 extern const struct cred
*override_creds(const struct cred
*);
165 extern void revert_creds(const struct cred
*);
166 extern struct cred
*clone_cred(const struct cred
*old
);
167 extern struct cred
*prepare_kernel_cred(struct task_struct
*);
168 extern int change_create_files_as(struct cred
*, struct inode
*);
169 extern int set_security_override(struct cred
*, u32
);
170 extern int set_security_override_from_ctx(struct cred
*, const char *);
171 extern int set_create_files_as(struct cred
*, struct inode
*);
172 extern void __init
cred_init(void);
175 * check for validity of credentials
177 #ifdef CONFIG_DEBUG_CREDENTIALS
178 extern void __invalid_creds(const struct cred
*, const char *, unsigned);
179 extern void __validate_process_creds(struct task_struct
*,
180 const char *, unsigned);
182 extern bool creds_are_invalid(const struct cred
*cred
);
184 static inline void __validate_creds(const struct cred
*cred
,
185 const char *file
, unsigned line
)
187 if (unlikely(creds_are_invalid(cred
)))
188 __invalid_creds(cred
, file
, line
);
191 #define validate_creds(cred) \
193 __validate_creds((cred), __FILE__, __LINE__); \
196 #define validate_process_creds() \
198 __validate_process_creds(current, __FILE__, __LINE__); \
201 extern void validate_creds_for_do_exit(struct task_struct
*);
203 static inline void validate_creds(const struct cred
*cred
)
206 static inline void validate_creds_for_do_exit(struct task_struct
*tsk
)
209 static inline void validate_process_creds(void)
214 static inline bool cap_ambient_invariant_ok(const struct cred
*cred
)
216 return cap_issubset(cred
->cap_ambient
,
217 cap_intersect(cred
->cap_permitted
,
218 cred
->cap_inheritable
));
222 * get_new_cred - Get a reference on a new set of credentials
223 * @cred: The new credentials to reference
225 * Get a reference on the specified set of new credentials. The caller must
226 * release the reference.
228 static inline struct cred
*get_new_cred(struct cred
*cred
)
230 atomic_inc(&cred
->usage
);
235 * get_cred - Get a reference on a set of credentials
236 * @cred: The credentials to reference
238 * Get a reference on the specified set of credentials. The caller must
239 * release the reference.
241 * This is used to deal with a committed set of credentials. Although the
242 * pointer is const, this will temporarily discard the const and increment the
243 * usage count. The purpose of this is to attempt to catch at compile time the
244 * accidental alteration of a set of credentials that should be considered
247 static inline const struct cred
*get_cred(const struct cred
*cred
)
249 struct cred
*nonconst_cred
= (struct cred
*) cred
;
250 validate_creds(cred
);
251 nonconst_cred
->non_rcu
= 0;
252 return get_new_cred(nonconst_cred
);
256 * put_cred - Release a reference to a set of credentials
257 * @cred: The credentials to release
259 * Release a reference to a set of credentials, deleting them when the last ref
262 * This takes a const pointer to a set of credentials because the credentials
263 * on task_struct are attached by const pointers to prevent accidental
264 * alteration of otherwise immutable credential sets.
266 static inline void put_cred(const struct cred
*_cred
)
268 struct cred
*cred
= (struct cred
*) _cred
;
270 validate_creds(cred
);
271 if (atomic_dec_and_test(&(cred
)->usage
))
276 * current_cred - Access the current task's subjective credentials
278 * Access the subjective credentials of the current task. RCU-safe,
279 * since nobody else can modify it.
281 #define current_cred() \
282 rcu_dereference_protected(current->cred, 1)
285 * current_real_cred - Access the current task's objective credentials
287 * Access the objective credentials of the current task. RCU-safe,
288 * since nobody else can modify it.
290 #define current_real_cred() \
291 rcu_dereference_protected(current->real_cred, 1)
294 * __task_cred - Access a task's objective credentials
295 * @task: The task to query
297 * Access the objective credentials of a task. The caller must hold the RCU
300 * The result of this function should not be passed directly to get_cred();
301 * rather get_task_cred() should be used instead.
303 #define __task_cred(task) \
304 rcu_dereference((task)->real_cred)
307 * get_current_cred - Get the current task's subjective credentials
309 * Get the subjective credentials of the current task, pinning them so that
310 * they can't go away. Accessing the current task's credentials directly is
313 #define get_current_cred() \
314 (get_cred(current_cred()))
317 * get_current_user - Get the current task's user_struct
319 * Get the user record of the current task, pinning it so that it can't go
322 #define get_current_user() \
324 struct user_struct *__u; \
325 const struct cred *__cred; \
326 __cred = current_cred(); \
327 __u = get_uid(__cred->user); \
332 * get_current_groups - Get the current task's supplementary group list
334 * Get the supplementary group list of the current task, pinning it so that it
337 #define get_current_groups() \
339 struct group_info *__groups; \
340 const struct cred *__cred; \
341 __cred = current_cred(); \
342 __groups = get_group_info(__cred->group_info); \
346 #define task_cred_xxx(task, xxx) \
348 __typeof__(((struct cred *)NULL)->xxx) ___val; \
350 ___val = __task_cred((task))->xxx; \
355 #define task_uid(task) (task_cred_xxx((task), uid))
356 #define task_euid(task) (task_cred_xxx((task), euid))
358 #define current_cred_xxx(xxx) \
360 current_cred()->xxx; \
363 #define current_uid() (current_cred_xxx(uid))
364 #define current_gid() (current_cred_xxx(gid))
365 #define current_euid() (current_cred_xxx(euid))
366 #define current_egid() (current_cred_xxx(egid))
367 #define current_suid() (current_cred_xxx(suid))
368 #define current_sgid() (current_cred_xxx(sgid))
369 #define current_fsuid() (current_cred_xxx(fsuid))
370 #define current_fsgid() (current_cred_xxx(fsgid))
371 #define current_cap() (current_cred_xxx(cap_effective))
372 #define current_user() (current_cred_xxx(user))
373 #define current_security() (current_cred_xxx(security))
375 extern struct user_namespace init_user_ns
;
376 #ifdef CONFIG_USER_NS
377 #define current_user_ns() (current_cred_xxx(user_ns))
379 static inline struct user_namespace
*current_user_ns(void)
381 return &init_user_ns
;
386 #define current_uid_gid(_uid, _gid) \
388 const struct cred *__cred; \
389 __cred = current_cred(); \
390 *(_uid) = __cred->uid; \
391 *(_gid) = __cred->gid; \
394 #define current_euid_egid(_euid, _egid) \
396 const struct cred *__cred; \
397 __cred = current_cred(); \
398 *(_euid) = __cred->euid; \
399 *(_egid) = __cred->egid; \
402 #define current_fsuid_fsgid(_fsuid, _fsgid) \
404 const struct cred *__cred; \
405 __cred = current_cred(); \
406 *(_fsuid) = __cred->fsuid; \
407 *(_fsgid) = __cred->fsgid; \
410 #endif /* _LINUX_CRED_H */