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
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);
68 static inline void groups_free(struct group_info *group_info)
72 static inline int in_group_p(kgid_t grp)
76 static inline int in_egroup_p(kgid_t grp)
81 extern int set_current_groups(struct group_info *);
82 extern void set_groups(struct cred *, struct group_info *);
83 extern int groups_search(const struct group_info *, kgid_t);
84 extern bool may_setgroups(void);
87 * The security context of a task
89 * The parts of the context break down into two categories:
91 * (1) The objective context of a task. These parts are used when some other
92 * task is attempting to affect this one.
94 * (2) The subjective context. These details are used when the task is acting
95 * upon another object, be that a file, a task, a key or whatever.
97 * Note that some members of this structure belong to both categories - the
98 * LSM security pointer for instance.
100 * A task has two security pointers. task->real_cred points to the objective
101 * context that defines that task's actual details. The objective part of this
102 * context is used whenever that task is acted upon.
104 * task->cred points to the subjective context that defines the details of how
105 * that task is going to act upon another object. This may be overridden
106 * temporarily to point to another security context, but normally points to the
107 * same context as task->real_cred.
111 #ifdef CONFIG_DEBUG_CREDENTIALS
112 atomic_t subscribers; /* number of processes subscribed */
115 #define CRED_MAGIC 0x43736564
116 #define CRED_MAGIC_DEAD 0x44656144
118 kuid_t uid; /* real UID of the task */
119 kgid_t gid; /* real GID of the task */
120 kuid_t suid; /* saved UID of the task */
121 kgid_t sgid; /* saved GID of the task */
122 kuid_t euid; /* effective UID of the task */
123 kgid_t egid; /* effective GID of the task */
124 kuid_t fsuid; /* UID for VFS ops */
125 kgid_t fsgid; /* GID for VFS ops */
126 unsigned securebits; /* SUID-less security management */
127 kernel_cap_t cap_inheritable; /* caps our children can inherit */
128 kernel_cap_t cap_permitted; /* caps we're permitted */
129 kernel_cap_t cap_effective; /* caps we can actually use */
130 kernel_cap_t cap_bset; /* capability bounding set */
131 kernel_cap_t cap_ambient; /* Ambient capability set */
133 unsigned char jit_keyring; /* default keyring to attach requested
135 struct key __rcu *session_keyring; /* keyring inherited over fork */
136 struct key *process_keyring; /* keyring private to this process */
137 struct key *thread_keyring; /* keyring private to this thread */
138 struct key *request_key_auth; /* assumed request_key authority */
140 #ifdef CONFIG_SECURITY
141 void *security; /* subjective LSM security */
143 struct user_struct *user; /* real user ID subscription */
144 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
145 struct group_info *group_info; /* supplementary groups for euid/fsgid */
146 struct rcu_head rcu; /* RCU deletion hook */
149 extern void __put_cred(struct cred *);
150 extern void exit_creds(struct task_struct *);
151 extern int copy_creds(struct task_struct *, unsigned long);
152 extern const struct cred *get_task_cred(struct task_struct *);
153 extern struct cred *cred_alloc_blank(void);
154 extern struct cred *prepare_creds(void);
155 extern struct cred *prepare_exec_creds(void);
156 extern int commit_creds(struct cred *);
157 extern void abort_creds(struct cred *);
158 extern const struct cred *override_creds(const struct cred *);
159 extern void revert_creds(const struct cred *);
160 extern struct cred *prepare_kernel_cred(struct task_struct *);
161 extern int change_create_files_as(struct cred *, struct inode *);
162 extern int set_security_override(struct cred *, u32);
163 extern int set_security_override_from_ctx(struct cred *, const char *);
164 extern int set_create_files_as(struct cred *, struct inode *);
165 extern void __init cred_init(void);
168 * check for validity of credentials
170 #ifdef CONFIG_DEBUG_CREDENTIALS
171 extern void __invalid_creds(const struct cred *, const char *, unsigned);
172 extern void __validate_process_creds(struct task_struct *,
173 const char *, unsigned);
175 extern bool creds_are_invalid(const struct cred *cred);
177 static inline void __validate_creds(const struct cred *cred,
178 const char *file, unsigned line)
180 if (unlikely(creds_are_invalid(cred)))
181 __invalid_creds(cred, file, line);
184 #define validate_creds(cred) \
186 __validate_creds((cred), __FILE__, __LINE__); \
189 #define validate_process_creds() \
191 __validate_process_creds(current, __FILE__, __LINE__); \
194 extern void validate_creds_for_do_exit(struct task_struct *);
196 static inline void validate_creds(const struct cred *cred)
199 static inline void validate_creds_for_do_exit(struct task_struct *tsk)
202 static inline void validate_process_creds(void)
207 static inline bool cap_ambient_invariant_ok(const struct cred *cred)
209 return cap_issubset(cred->cap_ambient,
210 cap_intersect(cred->cap_permitted,
211 cred->cap_inheritable));
215 * get_new_cred - Get a reference on a new set of credentials
216 * @cred: The new credentials to reference
218 * Get a reference on the specified set of new credentials. The caller must
219 * release the reference.
221 static inline struct cred *get_new_cred(struct cred *cred)
223 atomic_inc(&cred->usage);
228 * get_cred - Get a reference on a set of credentials
229 * @cred: The credentials to reference
231 * Get a reference on the specified set of credentials. The caller must
232 * release the reference.
234 * This is used to deal with a committed set of credentials. Although the
235 * pointer is const, this will temporarily discard the const and increment the
236 * usage count. The purpose of this is to attempt to catch at compile time the
237 * accidental alteration of a set of credentials that should be considered
240 static inline const struct cred *get_cred(const struct cred *cred)
242 struct cred *nonconst_cred = (struct cred *) cred;
243 validate_creds(cred);
244 return get_new_cred(nonconst_cred);
248 * put_cred - Release a reference to a set of credentials
249 * @cred: The credentials to release
251 * Release a reference to a set of credentials, deleting them when the last ref
254 * This takes a const pointer to a set of credentials because the credentials
255 * on task_struct are attached by const pointers to prevent accidental
256 * alteration of otherwise immutable credential sets.
258 static inline void put_cred(const struct cred *_cred)
260 struct cred *cred = (struct cred *) _cred;
262 validate_creds(cred);
263 if (atomic_dec_and_test(&(cred)->usage))
268 * current_cred - Access the current task's subjective credentials
270 * Access the subjective credentials of the current task. RCU-safe,
271 * since nobody else can modify it.
273 #define current_cred() \
274 rcu_dereference_protected(current->cred, 1)
277 * current_real_cred - Access the current task's objective credentials
279 * Access the objective credentials of the current task. RCU-safe,
280 * since nobody else can modify it.
282 #define current_real_cred() \
283 rcu_dereference_protected(current->real_cred, 1)
286 * __task_cred - Access a task's objective credentials
287 * @task: The task to query
289 * Access the objective credentials of a task. The caller must hold the RCU
292 * The result of this function should not be passed directly to get_cred();
293 * rather get_task_cred() should be used instead.
295 #define __task_cred(task) \
296 rcu_dereference((task)->real_cred)
299 * get_current_cred - Get the current task's subjective credentials
301 * Get the subjective credentials of the current task, pinning them so that
302 * they can't go away. Accessing the current task's credentials directly is
305 #define get_current_cred() \
306 (get_cred(current_cred()))
309 * get_current_user - Get the current task's user_struct
311 * Get the user record of the current task, pinning it so that it can't go
314 #define get_current_user() \
316 struct user_struct *__u; \
317 const struct cred *__cred; \
318 __cred = current_cred(); \
319 __u = get_uid(__cred->user); \
324 * get_current_groups - Get the current task's supplementary group list
326 * Get the supplementary group list of the current task, pinning it so that it
329 #define get_current_groups() \
331 struct group_info *__groups; \
332 const struct cred *__cred; \
333 __cred = current_cred(); \
334 __groups = get_group_info(__cred->group_info); \
338 #define task_cred_xxx(task, xxx) \
340 __typeof__(((struct cred *)NULL)->xxx) ___val; \
342 ___val = __task_cred((task))->xxx; \
347 #define task_uid(task) (task_cred_xxx((task), uid))
348 #define task_euid(task) (task_cred_xxx((task), euid))
350 #define current_cred_xxx(xxx) \
352 current_cred()->xxx; \
355 #define current_uid() (current_cred_xxx(uid))
356 #define current_gid() (current_cred_xxx(gid))
357 #define current_euid() (current_cred_xxx(euid))
358 #define current_egid() (current_cred_xxx(egid))
359 #define current_suid() (current_cred_xxx(suid))
360 #define current_sgid() (current_cred_xxx(sgid))
361 #define current_fsuid() (current_cred_xxx(fsuid))
362 #define current_fsgid() (current_cred_xxx(fsgid))
363 #define current_cap() (current_cred_xxx(cap_effective))
364 #define current_user() (current_cred_xxx(user))
365 #define current_security() (current_cred_xxx(security))
367 extern struct user_namespace init_user_ns;
368 #ifdef CONFIG_USER_NS
369 #define current_user_ns() (current_cred_xxx(user_ns))
371 static inline struct user_namespace *current_user_ns(void)
373 return &init_user_ns;
378 #define current_uid_gid(_uid, _gid) \
380 const struct cred *__cred; \
381 __cred = current_cred(); \
382 *(_uid) = __cred->uid; \
383 *(_gid) = __cred->gid; \
386 #define current_euid_egid(_euid, _egid) \
388 const struct cred *__cred; \
389 __cred = current_cred(); \
390 *(_euid) = __cred->euid; \
391 *(_egid) = __cred->egid; \
394 #define current_fsuid_fsgid(_fsuid, _fsgid) \
396 const struct cred *__cred; \
397 __cred = current_cred(); \
398 *(_fsuid) = __cred->fsuid; \
399 *(_fsgid) = __cred->fsgid; \
402 #endif /* _LINUX_CRED_H */