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 */
148 struct rcu_head rcu
; /* RCU deletion hook */
149 } __randomize_layout
;
151 extern void __put_cred(struct cred
*);
152 extern void exit_creds(struct task_struct
*);
153 extern int copy_creds(struct task_struct
*, unsigned long);
154 extern const struct cred
*get_task_cred(struct task_struct
*);
155 extern struct cred
*cred_alloc_blank(void);
156 extern struct cred
*prepare_creds(void);
157 extern struct cred
*prepare_exec_creds(void);
158 extern int commit_creds(struct cred
*);
159 extern void abort_creds(struct cred
*);
160 extern const struct cred
*override_creds(const struct cred
*);
161 extern void revert_creds(const struct cred
*);
162 extern struct cred
*clone_cred(const struct cred
*old
);
163 extern struct cred
*prepare_kernel_cred(struct task_struct
*);
164 extern int change_create_files_as(struct cred
*, struct inode
*);
165 extern int set_security_override(struct cred
*, u32
);
166 extern int set_security_override_from_ctx(struct cred
*, const char *);
167 extern int set_create_files_as(struct cred
*, struct inode
*);
168 extern void __init
cred_init(void);
171 * check for validity of credentials
173 #ifdef CONFIG_DEBUG_CREDENTIALS
174 extern void __invalid_creds(const struct cred
*, const char *, unsigned);
175 extern void __validate_process_creds(struct task_struct
*,
176 const char *, unsigned);
178 extern bool creds_are_invalid(const struct cred
*cred
);
180 static inline void __validate_creds(const struct cred
*cred
,
181 const char *file
, unsigned line
)
183 if (unlikely(creds_are_invalid(cred
)))
184 __invalid_creds(cred
, file
, line
);
187 #define validate_creds(cred) \
189 __validate_creds((cred), __FILE__, __LINE__); \
192 #define validate_process_creds() \
194 __validate_process_creds(current, __FILE__, __LINE__); \
197 extern void validate_creds_for_do_exit(struct task_struct
*);
199 static inline void validate_creds(const struct cred
*cred
)
202 static inline void validate_creds_for_do_exit(struct task_struct
*tsk
)
205 static inline void validate_process_creds(void)
210 static inline bool cap_ambient_invariant_ok(const struct cred
*cred
)
212 return cap_issubset(cred
->cap_ambient
,
213 cap_intersect(cred
->cap_permitted
,
214 cred
->cap_inheritable
));
218 * get_new_cred - Get a reference on a new set of credentials
219 * @cred: The new credentials to reference
221 * Get a reference on the specified set of new credentials. The caller must
222 * release the reference.
224 static inline struct cred
*get_new_cred(struct cred
*cred
)
226 atomic_inc(&cred
->usage
);
231 * get_cred - Get a reference on a set of credentials
232 * @cred: The credentials to reference
234 * Get a reference on the specified set of credentials. The caller must
235 * release the reference.
237 * This is used to deal with a committed set of credentials. Although the
238 * pointer is const, this will temporarily discard the const and increment the
239 * usage count. The purpose of this is to attempt to catch at compile time the
240 * accidental alteration of a set of credentials that should be considered
243 static inline const struct cred
*get_cred(const struct cred
*cred
)
245 struct cred
*nonconst_cred
= (struct cred
*) cred
;
246 validate_creds(cred
);
247 return get_new_cred(nonconst_cred
);
251 * put_cred - Release a reference to a set of credentials
252 * @cred: The credentials to release
254 * Release a reference to a set of credentials, deleting them when the last ref
257 * This takes a const pointer to a set of credentials because the credentials
258 * on task_struct are attached by const pointers to prevent accidental
259 * alteration of otherwise immutable credential sets.
261 static inline void put_cred(const struct cred
*_cred
)
263 struct cred
*cred
= (struct cred
*) _cred
;
265 validate_creds(cred
);
266 if (atomic_dec_and_test(&(cred
)->usage
))
271 * current_cred - Access the current task's subjective credentials
273 * Access the subjective credentials of the current task. RCU-safe,
274 * since nobody else can modify it.
276 #define current_cred() \
277 rcu_dereference_protected(current->cred, 1)
280 * current_real_cred - Access the current task's objective credentials
282 * Access the objective credentials of the current task. RCU-safe,
283 * since nobody else can modify it.
285 #define current_real_cred() \
286 rcu_dereference_protected(current->real_cred, 1)
289 * __task_cred - Access a task's objective credentials
290 * @task: The task to query
292 * Access the objective credentials of a task. The caller must hold the RCU
295 * The result of this function should not be passed directly to get_cred();
296 * rather get_task_cred() should be used instead.
298 #define __task_cred(task) \
299 rcu_dereference((task)->real_cred)
302 * get_current_cred - Get the current task's subjective credentials
304 * Get the subjective credentials of the current task, pinning them so that
305 * they can't go away. Accessing the current task's credentials directly is
308 #define get_current_cred() \
309 (get_cred(current_cred()))
312 * get_current_user - Get the current task's user_struct
314 * Get the user record of the current task, pinning it so that it can't go
317 #define get_current_user() \
319 struct user_struct *__u; \
320 const struct cred *__cred; \
321 __cred = current_cred(); \
322 __u = get_uid(__cred->user); \
327 * get_current_groups - Get the current task's supplementary group list
329 * Get the supplementary group list of the current task, pinning it so that it
332 #define get_current_groups() \
334 struct group_info *__groups; \
335 const struct cred *__cred; \
336 __cred = current_cred(); \
337 __groups = get_group_info(__cred->group_info); \
341 #define task_cred_xxx(task, xxx) \
343 __typeof__(((struct cred *)NULL)->xxx) ___val; \
345 ___val = __task_cred((task))->xxx; \
350 #define task_uid(task) (task_cred_xxx((task), uid))
351 #define task_euid(task) (task_cred_xxx((task), euid))
353 #define current_cred_xxx(xxx) \
355 current_cred()->xxx; \
358 #define current_uid() (current_cred_xxx(uid))
359 #define current_gid() (current_cred_xxx(gid))
360 #define current_euid() (current_cred_xxx(euid))
361 #define current_egid() (current_cred_xxx(egid))
362 #define current_suid() (current_cred_xxx(suid))
363 #define current_sgid() (current_cred_xxx(sgid))
364 #define current_fsuid() (current_cred_xxx(fsuid))
365 #define current_fsgid() (current_cred_xxx(fsgid))
366 #define current_cap() (current_cred_xxx(cap_effective))
367 #define current_user() (current_cred_xxx(user))
368 #define current_security() (current_cred_xxx(security))
370 extern struct user_namespace init_user_ns
;
371 #ifdef CONFIG_USER_NS
372 #define current_user_ns() (current_cred_xxx(user_ns))
374 static inline struct user_namespace
*current_user_ns(void)
376 return &init_user_ns
;
381 #define current_uid_gid(_uid, _gid) \
383 const struct cred *__cred; \
384 __cred = current_cred(); \
385 *(_uid) = __cred->uid; \
386 *(_gid) = __cred->gid; \
389 #define current_euid_egid(_euid, _egid) \
391 const struct cred *__cred; \
392 __cred = current_cred(); \
393 *(_euid) = __cred->euid; \
394 *(_egid) = __cred->egid; \
397 #define current_fsuid_fsgid(_fsuid, _fsgid) \
399 const struct cred *__cred; \
400 __cred = current_cred(); \
401 *(_fsuid) = __cred->fsuid; \
402 *(_fsgid) = __cred->fsgid; \
405 #endif /* _LINUX_CRED_H */