1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Credentials management - see Documentation/security/credentials.rst
4 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
11 #include <linux/capability.h>
12 #include <linux/init.h>
13 #include <linux/key.h>
14 #include <linux/atomic.h>
15 #include <linux/uidgid.h>
16 #include <linux/sched.h>
17 #include <linux/sched/user.h>
23 * COW Supplementary groups list
32 * get_group_info - Get a reference to a group info structure
33 * @group_info: The group info to reference
35 * This gets a reference to a set of supplementary groups.
37 * If the caller is accessing a task's credentials, they must hold the RCU read
40 static inline struct group_info
*get_group_info(struct group_info
*gi
)
42 atomic_inc(&gi
->usage
);
47 * put_group_info - Release a reference to a group info structure
48 * @group_info: The group info to release
50 #define put_group_info(group_info) \
52 if (atomic_dec_and_test(&(group_info)->usage)) \
53 groups_free(group_info); \
56 #ifdef CONFIG_MULTIUSER
57 extern struct group_info
*groups_alloc(int);
58 extern void groups_free(struct group_info
*);
60 extern int in_group_p(kgid_t
);
61 extern int in_egroup_p(kgid_t
);
62 extern int groups_search(const struct group_info
*, kgid_t
);
64 extern int set_current_groups(struct group_info
*);
65 extern void set_groups(struct cred
*, struct group_info
*);
66 extern bool may_setgroups(void);
67 extern void groups_sort(struct group_info
*);
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
)
81 static inline int groups_search(const struct group_info
*group_info
, kgid_t grp
)
88 * The security context of a task
90 * The parts of the context break down into two categories:
92 * (1) The objective context of a task. These parts are used when some other
93 * task is attempting to affect this one.
95 * (2) The subjective context. These details are used when the task is acting
96 * upon another object, be that a file, a task, a key or whatever.
98 * Note that some members of this structure belong to both categories - the
99 * LSM security pointer for instance.
101 * A task has two security pointers. task->real_cred points to the objective
102 * context that defines that task's actual details. The objective part of this
103 * context is used whenever that task is acted upon.
105 * task->cred points to the subjective context that defines the details of how
106 * that task is going to act upon another object. This may be overridden
107 * temporarily to point to another security context, but normally points to the
108 * same context as task->real_cred.
112 #ifdef CONFIG_DEBUG_CREDENTIALS
113 atomic_t subscribers
; /* number of processes subscribed */
116 #define CRED_MAGIC 0x43736564
117 #define CRED_MAGIC_DEAD 0x44656144
119 kuid_t uid
; /* real UID of the task */
120 kgid_t gid
; /* real GID of the task */
121 kuid_t suid
; /* saved UID of the task */
122 kgid_t sgid
; /* saved GID of the task */
123 kuid_t euid
; /* effective UID of the task */
124 kgid_t egid
; /* effective GID of the task */
125 kuid_t fsuid
; /* UID for VFS ops */
126 kgid_t fsgid
; /* GID for VFS ops */
127 unsigned securebits
; /* SUID-less security management */
128 kernel_cap_t cap_inheritable
; /* caps our children can inherit */
129 kernel_cap_t cap_permitted
; /* caps we're permitted */
130 kernel_cap_t cap_effective
; /* caps we can actually use */
131 kernel_cap_t cap_bset
; /* capability bounding set */
132 kernel_cap_t cap_ambient
; /* Ambient capability set */
134 unsigned char jit_keyring
; /* default keyring to attach requested
136 struct key
*session_keyring
; /* keyring inherited over fork */
137 struct key
*process_keyring
; /* keyring private to this process */
138 struct key
*thread_keyring
; /* keyring private to this thread */
139 struct key
*request_key_auth
; /* assumed request_key authority */
141 #ifdef CONFIG_SECURITY
142 void *security
; /* LSM security */
144 struct user_struct
*user
; /* real user ID subscription */
145 struct user_namespace
*user_ns
; /* user_ns the caps and keyrings are relative to. */
146 struct ucounts
*ucounts
;
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
*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);
173 extern int set_cred_ucounts(struct cred
*);
176 * check for validity of credentials
178 #ifdef CONFIG_DEBUG_CREDENTIALS
179 extern void __invalid_creds(const struct cred
*, const char *, unsigned);
180 extern void __validate_process_creds(struct task_struct
*,
181 const char *, unsigned);
183 extern bool creds_are_invalid(const struct cred
*cred
);
185 static inline void __validate_creds(const struct cred
*cred
,
186 const char *file
, unsigned line
)
188 if (unlikely(creds_are_invalid(cred
)))
189 __invalid_creds(cred
, file
, line
);
192 #define validate_creds(cred) \
194 __validate_creds((cred), __FILE__, __LINE__); \
197 #define validate_process_creds() \
199 __validate_process_creds(current, __FILE__, __LINE__); \
202 extern void validate_creds_for_do_exit(struct task_struct
*);
204 static inline void validate_creds(const struct cred
*cred
)
207 static inline void validate_creds_for_do_exit(struct task_struct
*tsk
)
210 static inline void validate_process_creds(void)
215 static inline bool cap_ambient_invariant_ok(const struct cred
*cred
)
217 return cap_issubset(cred
->cap_ambient
,
218 cap_intersect(cred
->cap_permitted
,
219 cred
->cap_inheritable
));
223 * get_new_cred - Get a reference on a new set of credentials
224 * @cred: The new credentials to reference
226 * Get a reference on the specified set of new credentials. The caller must
227 * release the reference.
229 static inline struct cred
*get_new_cred(struct cred
*cred
)
231 atomic_inc(&cred
->usage
);
236 * get_cred - Get a reference on a set of credentials
237 * @cred: The credentials to reference
239 * Get a reference on the specified set of credentials. The caller must
240 * release the reference. If %NULL is passed, it is returned with no action.
242 * This is used to deal with a committed set of credentials. Although the
243 * pointer is const, this will temporarily discard the const and increment the
244 * usage count. The purpose of this is to attempt to catch at compile time the
245 * accidental alteration of a set of credentials that should be considered
248 static inline const struct cred
*get_cred(const struct cred
*cred
)
250 struct cred
*nonconst_cred
= (struct cred
*) cred
;
253 validate_creds(cred
);
254 nonconst_cred
->non_rcu
= 0;
255 return get_new_cred(nonconst_cred
);
258 static inline const struct cred
*get_cred_rcu(const struct cred
*cred
)
260 struct cred
*nonconst_cred
= (struct cred
*) cred
;
263 if (!atomic_inc_not_zero(&nonconst_cred
->usage
))
265 validate_creds(cred
);
266 nonconst_cred
->non_rcu
= 0;
271 * put_cred - Release a reference to a set of credentials
272 * @cred: The credentials to release
274 * Release a reference to a set of credentials, deleting them when the last ref
275 * is released. If %NULL is passed, nothing is done.
277 * This takes a const pointer to a set of credentials because the credentials
278 * on task_struct are attached by const pointers to prevent accidental
279 * alteration of otherwise immutable credential sets.
281 static inline void put_cred(const struct cred
*_cred
)
283 struct cred
*cred
= (struct cred
*) _cred
;
286 validate_creds(cred
);
287 if (atomic_dec_and_test(&(cred
)->usage
))
293 * current_cred - Access the current task's subjective credentials
295 * Access the subjective credentials of the current task. RCU-safe,
296 * since nobody else can modify it.
298 #define current_cred() \
299 rcu_dereference_protected(current->cred, 1)
302 * current_real_cred - Access the current task's objective credentials
304 * Access the objective credentials of the current task. RCU-safe,
305 * since nobody else can modify it.
307 #define current_real_cred() \
308 rcu_dereference_protected(current->real_cred, 1)
311 * __task_cred - Access a task's objective credentials
312 * @task: The task to query
314 * Access the objective credentials of a task. The caller must hold the RCU
317 * The result of this function should not be passed directly to get_cred();
318 * rather get_task_cred() should be used instead.
320 #define __task_cred(task) \
321 rcu_dereference((task)->real_cred)
324 * get_current_cred - Get the current task's subjective credentials
326 * Get the subjective credentials of the current task, pinning them so that
327 * they can't go away. Accessing the current task's credentials directly is
330 #define get_current_cred() \
331 (get_cred(current_cred()))
334 * get_current_user - Get the current task's user_struct
336 * Get the user record of the current task, pinning it so that it can't go
339 #define get_current_user() \
341 struct user_struct *__u; \
342 const struct cred *__cred; \
343 __cred = current_cred(); \
344 __u = get_uid(__cred->user); \
349 * get_current_groups - Get the current task's supplementary group list
351 * Get the supplementary group list of the current task, pinning it so that it
354 #define get_current_groups() \
356 struct group_info *__groups; \
357 const struct cred *__cred; \
358 __cred = current_cred(); \
359 __groups = get_group_info(__cred->group_info); \
363 #define task_cred_xxx(task, xxx) \
365 __typeof__(((struct cred *)NULL)->xxx) ___val; \
367 ___val = __task_cred((task))->xxx; \
372 #define task_uid(task) (task_cred_xxx((task), uid))
373 #define task_euid(task) (task_cred_xxx((task), euid))
374 #define task_ucounts(task) (task_cred_xxx((task), ucounts))
376 #define current_cred_xxx(xxx) \
378 current_cred()->xxx; \
381 #define current_uid() (current_cred_xxx(uid))
382 #define current_gid() (current_cred_xxx(gid))
383 #define current_euid() (current_cred_xxx(euid))
384 #define current_egid() (current_cred_xxx(egid))
385 #define current_suid() (current_cred_xxx(suid))
386 #define current_sgid() (current_cred_xxx(sgid))
387 #define current_fsuid() (current_cred_xxx(fsuid))
388 #define current_fsgid() (current_cred_xxx(fsgid))
389 #define current_cap() (current_cred_xxx(cap_effective))
390 #define current_user() (current_cred_xxx(user))
391 #define current_ucounts() (current_cred_xxx(ucounts))
393 extern struct user_namespace init_user_ns
;
394 #ifdef CONFIG_USER_NS
395 #define current_user_ns() (current_cred_xxx(user_ns))
397 static inline struct user_namespace
*current_user_ns(void)
399 return &init_user_ns
;
404 #define current_uid_gid(_uid, _gid) \
406 const struct cred *__cred; \
407 __cred = current_cred(); \
408 *(_uid) = __cred->uid; \
409 *(_gid) = __cred->gid; \
412 #define current_euid_egid(_euid, _egid) \
414 const struct cred *__cred; \
415 __cred = current_cred(); \
416 *(_euid) = __cred->euid; \
417 *(_egid) = __cred->egid; \
420 #define current_fsuid_fsgid(_fsuid, _fsgid) \
422 const struct cred *__cred; \
423 __cred = current_cred(); \
424 *(_fsuid) = __cred->fsuid; \
425 *(_fsgid) = __cred->fsgid; \
428 #endif /* _LINUX_CRED_H */