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/atomic.h>
19 #include <linux/uidgid.h>
20 #include <linux/sched.h>
21 #include <linux/sched/user.h>
27 * COW Supplementary groups list
36 * get_group_info - Get a reference to a group info structure
37 * @group_info: The group info to reference
39 * This gets a reference to a set of supplementary groups.
41 * If the caller is accessing a task's credentials, they must hold the RCU read
44 static inline struct group_info
*get_group_info(struct group_info
*gi
)
46 atomic_inc(&gi
->usage
);
51 * put_group_info - Release a reference to a group info structure
52 * @group_info: The group info to release
54 #define put_group_info(group_info) \
56 if (atomic_dec_and_test(&(group_info)->usage)) \
57 groups_free(group_info); \
60 extern struct group_info init_groups
;
61 #ifdef CONFIG_MULTIUSER
62 extern struct group_info
*groups_alloc(int);
63 extern void groups_free(struct group_info
*);
65 extern int in_group_p(kgid_t
);
66 extern int in_egroup_p(kgid_t
);
67 extern int groups_search(const struct group_info
*, kgid_t
);
69 extern int set_current_groups(struct group_info
*);
70 extern void set_groups(struct cred
*, struct group_info
*);
71 extern bool may_setgroups(void);
72 extern void groups_sort(struct group_info
*);
74 static inline void groups_free(struct group_info
*group_info
)
78 static inline int in_group_p(kgid_t grp
)
82 static inline int in_egroup_p(kgid_t grp
)
86 static inline int groups_search(const struct group_info
*group_info
, kgid_t grp
)
93 * The security context of a task
95 * The parts of the context break down into two categories:
97 * (1) The objective context of a task. These parts are used when some other
98 * task is attempting to affect this one.
100 * (2) The subjective context. These details are used when the task is acting
101 * upon another object, be that a file, a task, a key or whatever.
103 * Note that some members of this structure belong to both categories - the
104 * LSM security pointer for instance.
106 * A task has two security pointers. task->real_cred points to the objective
107 * context that defines that task's actual details. The objective part of this
108 * context is used whenever that task is acted upon.
110 * task->cred points to the subjective context that defines the details of how
111 * that task is going to act upon another object. This may be overridden
112 * temporarily to point to another security context, but normally points to the
113 * same context as task->real_cred.
117 #ifdef CONFIG_DEBUG_CREDENTIALS
118 atomic_t subscribers
; /* number of processes subscribed */
121 #define CRED_MAGIC 0x43736564
122 #define CRED_MAGIC_DEAD 0x44656144
124 kuid_t uid
; /* real UID of the task */
125 kgid_t gid
; /* real GID of the task */
126 kuid_t suid
; /* saved UID of the task */
127 kgid_t sgid
; /* saved GID of the task */
128 kuid_t euid
; /* effective UID of the task */
129 kgid_t egid
; /* effective GID of the task */
130 kuid_t fsuid
; /* UID for VFS ops */
131 kgid_t fsgid
; /* GID for VFS ops */
132 unsigned securebits
; /* SUID-less security management */
133 kernel_cap_t cap_inheritable
; /* caps our children can inherit */
134 kernel_cap_t cap_permitted
; /* caps we're permitted */
135 kernel_cap_t cap_effective
; /* caps we can actually use */
136 kernel_cap_t cap_bset
; /* capability bounding set */
137 kernel_cap_t cap_ambient
; /* Ambient capability set */
139 unsigned char jit_keyring
; /* default keyring to attach requested
141 struct key __rcu
*session_keyring
; /* keyring inherited over fork */
142 struct key
*process_keyring
; /* keyring private to this process */
143 struct key
*thread_keyring
; /* keyring private to this thread */
144 struct key
*request_key_auth
; /* assumed request_key authority */
146 #ifdef CONFIG_SECURITY
147 void *security
; /* subjective LSM security */
149 struct user_struct
*user
; /* real user ID subscription */
150 struct user_namespace
*user_ns
; /* user_ns the caps and keyrings are relative to. */
151 struct group_info
*group_info
; /* supplementary groups for euid/fsgid */
152 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
*prepare_kernel_cred(struct task_struct
*);
167 extern int change_create_files_as(struct cred
*, struct inode
*);
168 extern int set_security_override(struct cred
*, u32
);
169 extern int set_security_override_from_ctx(struct cred
*, const char *);
170 extern int set_create_files_as(struct cred
*, struct inode
*);
171 extern int cred_fscmp(const struct cred
*, const struct cred
*);
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. If %NULL is passed, it is returned with no action.
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
;
252 validate_creds(cred
);
253 return get_new_cred(nonconst_cred
);
256 static inline const struct cred
*get_cred_rcu(const struct cred
*cred
)
258 struct cred
*nonconst_cred
= (struct cred
*) cred
;
261 if (!atomic_inc_not_zero(&nonconst_cred
->usage
))
263 validate_creds(cred
);
268 * put_cred - Release a reference to a set of credentials
269 * @cred: The credentials to release
271 * Release a reference to a set of credentials, deleting them when the last ref
272 * is released. If %NULL is passed, nothing is done.
274 * This takes a const pointer to a set of credentials because the credentials
275 * on task_struct are attached by const pointers to prevent accidental
276 * alteration of otherwise immutable credential sets.
278 static inline void put_cred(const struct cred
*_cred
)
280 struct cred
*cred
= (struct cred
*) _cred
;
283 validate_creds(cred
);
284 if (atomic_dec_and_test(&(cred
)->usage
))
290 * current_cred - Access the current task's subjective credentials
292 * Access the subjective credentials of the current task. RCU-safe,
293 * since nobody else can modify it.
295 #define current_cred() \
296 rcu_dereference_protected(current->cred, 1)
299 * current_real_cred - Access the current task's objective credentials
301 * Access the objective credentials of the current task. RCU-safe,
302 * since nobody else can modify it.
304 #define current_real_cred() \
305 rcu_dereference_protected(current->real_cred, 1)
308 * __task_cred - Access a task's objective credentials
309 * @task: The task to query
311 * Access the objective credentials of a task. The caller must hold the RCU
314 * The result of this function should not be passed directly to get_cred();
315 * rather get_task_cred() should be used instead.
317 #define __task_cred(task) \
318 rcu_dereference((task)->real_cred)
321 * get_current_cred - Get the current task's subjective credentials
323 * Get the subjective credentials of the current task, pinning them so that
324 * they can't go away. Accessing the current task's credentials directly is
327 #define get_current_cred() \
328 (get_cred(current_cred()))
331 * get_current_user - Get the current task's user_struct
333 * Get the user record of the current task, pinning it so that it can't go
336 #define get_current_user() \
338 struct user_struct *__u; \
339 const struct cred *__cred; \
340 __cred = current_cred(); \
341 __u = get_uid(__cred->user); \
346 * get_current_groups - Get the current task's supplementary group list
348 * Get the supplementary group list of the current task, pinning it so that it
351 #define get_current_groups() \
353 struct group_info *__groups; \
354 const struct cred *__cred; \
355 __cred = current_cred(); \
356 __groups = get_group_info(__cred->group_info); \
360 #define task_cred_xxx(task, xxx) \
362 __typeof__(((struct cred *)NULL)->xxx) ___val; \
364 ___val = __task_cred((task))->xxx; \
369 #define task_uid(task) (task_cred_xxx((task), uid))
370 #define task_euid(task) (task_cred_xxx((task), euid))
372 #define current_cred_xxx(xxx) \
374 current_cred()->xxx; \
377 #define current_uid() (current_cred_xxx(uid))
378 #define current_gid() (current_cred_xxx(gid))
379 #define current_euid() (current_cred_xxx(euid))
380 #define current_egid() (current_cred_xxx(egid))
381 #define current_suid() (current_cred_xxx(suid))
382 #define current_sgid() (current_cred_xxx(sgid))
383 #define current_fsuid() (current_cred_xxx(fsuid))
384 #define current_fsgid() (current_cred_xxx(fsgid))
385 #define current_cap() (current_cred_xxx(cap_effective))
386 #define current_user() (current_cred_xxx(user))
387 #define current_security() (current_cred_xxx(security))
389 extern struct user_namespace init_user_ns
;
390 #ifdef CONFIG_USER_NS
391 #define current_user_ns() (current_cred_xxx(user_ns))
393 static inline struct user_namespace
*current_user_ns(void)
395 return &init_user_ns
;
400 #define current_uid_gid(_uid, _gid) \
402 const struct cred *__cred; \
403 __cred = current_cred(); \
404 *(_uid) = __cred->uid; \
405 *(_gid) = __cred->gid; \
408 #define current_euid_egid(_euid, _egid) \
410 const struct cred *__cred; \
411 __cred = current_cred(); \
412 *(_euid) = __cred->euid; \
413 *(_egid) = __cred->egid; \
416 #define current_fsuid_fsgid(_fsuid, _fsgid) \
418 const struct cred *__cred; \
419 __cred = current_cred(); \
420 *(_fsuid) = __cred->fsuid; \
421 *(_fsgid) = __cred->fsgid; \
424 #endif /* _LINUX_CRED_H */