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);
85 extern void groups_sort(struct group_info *);
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 __rcu *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; /* subjective 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 group_info *group_info; /* supplementary groups for euid/fsgid */
149 int non_rcu; /* Can we skip RCU deletion? */
150 struct rcu_head rcu; /* RCU deletion hook */
154 extern void __put_cred(struct cred *);
155 extern void exit_creds(struct task_struct *);
156 extern int copy_creds(struct task_struct *, unsigned long);
157 extern const struct cred *get_task_cred(struct task_struct *);
158 extern struct cred *cred_alloc_blank(void);
159 extern struct cred *prepare_creds(void);
160 extern struct cred *prepare_exec_creds(void);
161 extern int commit_creds(struct cred *);
162 extern void abort_creds(struct cred *);
163 extern const struct cred *override_creds(const struct cred *);
164 extern void revert_creds(const struct cred *);
165 extern struct cred *prepare_kernel_cred(struct task_struct *);
166 extern int change_create_files_as(struct cred *, struct inode *);
167 extern int set_security_override(struct cred *, u32);
168 extern int set_security_override_from_ctx(struct cred *, const char *);
169 extern int set_create_files_as(struct cred *, struct inode *);
170 extern void __init cred_init(void);
173 * check for validity of credentials
175 #ifdef CONFIG_DEBUG_CREDENTIALS
176 extern void __invalid_creds(const struct cred *, const char *, unsigned);
177 extern void __validate_process_creds(struct task_struct *,
178 const char *, unsigned);
180 extern bool creds_are_invalid(const struct cred *cred);
182 static inline void __validate_creds(const struct cred *cred,
183 const char *file, unsigned line)
185 if (unlikely(creds_are_invalid(cred)))
186 __invalid_creds(cred, file, line);
189 #define validate_creds(cred) \
191 __validate_creds((cred), __FILE__, __LINE__); \
194 #define validate_process_creds() \
196 __validate_process_creds(current, __FILE__, __LINE__); \
199 extern void validate_creds_for_do_exit(struct task_struct *);
201 static inline void validate_creds(const struct cred *cred)
204 static inline void validate_creds_for_do_exit(struct task_struct *tsk)
207 static inline void validate_process_creds(void)
212 static inline bool cap_ambient_invariant_ok(const struct cred *cred)
214 return cap_issubset(cred->cap_ambient,
215 cap_intersect(cred->cap_permitted,
216 cred->cap_inheritable));
220 * get_new_cred - Get a reference on a new set of credentials
221 * @cred: The new credentials to reference
223 * Get a reference on the specified set of new credentials. The caller must
224 * release the reference.
226 static inline struct cred *get_new_cred(struct cred *cred)
228 atomic_inc(&cred->usage);
233 * get_cred - Get a reference on a set of credentials
234 * @cred: The credentials to reference
236 * Get a reference on the specified set of credentials. The caller must
237 * release the reference. If %NULL is passed, it is returned with no action.
239 * This is used to deal with a committed set of credentials. Although the
240 * pointer is const, this will temporarily discard the const and increment the
241 * usage count. The purpose of this is to attempt to catch at compile time the
242 * accidental alteration of a set of credentials that should be considered
245 static inline const struct cred *get_cred(const struct cred *cred)
247 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
260 * is released. If %NULL is passed, nothing is done.
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;
271 validate_creds(cred);
272 if (atomic_dec_and_test(&(cred)->usage))
278 * current_cred - Access the current task's subjective credentials
280 * Access the subjective credentials of the current task. RCU-safe,
281 * since nobody else can modify it.
283 #define current_cred() \
284 rcu_dereference_protected(current->cred, 1)
287 * current_real_cred - Access the current task's objective credentials
289 * Access the objective credentials of the current task. RCU-safe,
290 * since nobody else can modify it.
292 #define current_real_cred() \
293 rcu_dereference_protected(current->real_cred, 1)
296 * __task_cred - Access a task's objective credentials
297 * @task: The task to query
299 * Access the objective credentials of a task. The caller must hold the RCU
302 * The result of this function should not be passed directly to get_cred();
303 * rather get_task_cred() should be used instead.
305 #define __task_cred(task) \
306 rcu_dereference((task)->real_cred)
309 * get_current_cred - Get the current task's subjective credentials
311 * Get the subjective credentials of the current task, pinning them so that
312 * they can't go away. Accessing the current task's credentials directly is
315 #define get_current_cred() \
316 (get_cred(current_cred()))
319 * get_current_user - Get the current task's user_struct
321 * Get the user record of the current task, pinning it so that it can't go
324 #define get_current_user() \
326 struct user_struct *__u; \
327 const struct cred *__cred; \
328 __cred = current_cred(); \
329 __u = get_uid(__cred->user); \
334 * get_current_groups - Get the current task's supplementary group list
336 * Get the supplementary group list of the current task, pinning it so that it
339 #define get_current_groups() \
341 struct group_info *__groups; \
342 const struct cred *__cred; \
343 __cred = current_cred(); \
344 __groups = get_group_info(__cred->group_info); \
348 #define task_cred_xxx(task, xxx) \
350 __typeof__(((struct cred *)NULL)->xxx) ___val; \
352 ___val = __task_cred((task))->xxx; \
357 #define task_uid(task) (task_cred_xxx((task), uid))
358 #define task_euid(task) (task_cred_xxx((task), euid))
360 #define current_cred_xxx(xxx) \
362 current_cred()->xxx; \
365 #define current_uid() (current_cred_xxx(uid))
366 #define current_gid() (current_cred_xxx(gid))
367 #define current_euid() (current_cred_xxx(euid))
368 #define current_egid() (current_cred_xxx(egid))
369 #define current_suid() (current_cred_xxx(suid))
370 #define current_sgid() (current_cred_xxx(sgid))
371 #define current_fsuid() (current_cred_xxx(fsuid))
372 #define current_fsgid() (current_cred_xxx(fsgid))
373 #define current_cap() (current_cred_xxx(cap_effective))
374 #define current_user() (current_cred_xxx(user))
375 #define current_security() (current_cred_xxx(security))
377 extern struct user_namespace init_user_ns;
378 #ifdef CONFIG_USER_NS
379 #define current_user_ns() (current_cred_xxx(user_ns))
381 static inline struct user_namespace *current_user_ns(void)
383 return &init_user_ns;
388 #define current_uid_gid(_uid, _gid) \
390 const struct cred *__cred; \
391 __cred = current_cred(); \
392 *(_uid) = __cred->uid; \
393 *(_gid) = __cred->gid; \
396 #define current_euid_egid(_euid, _egid) \
398 const struct cred *__cred; \
399 __cred = current_cred(); \
400 *(_euid) = __cred->euid; \
401 *(_egid) = __cred->egid; \
404 #define current_fsuid_fsgid(_fsuid, _fsgid) \
406 const struct cred *__cred; \
407 __cred = current_cred(); \
408 *(_fsuid) = __cred->fsuid; \
409 *(_fsgid) = __cred->fsgid; \
412 #endif /* _LINUX_CRED_H */