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
29 #define NGROUPS_SMALL 32
30 #define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t)))
36 kgid_t small_block[NGROUPS_SMALL];
41 * get_group_info - Get a reference to a group info structure
42 * @group_info: The group info to reference
44 * This gets a reference to a set of supplementary groups.
46 * If the caller is accessing a task's credentials, they must hold the RCU read
49 static inline struct group_info *get_group_info(struct group_info *gi)
51 atomic_inc(&gi->usage);
56 * put_group_info - Release a reference to a group info structure
57 * @group_info: The group info to release
59 #define put_group_info(group_info) \
61 if (atomic_dec_and_test(&(group_info)->usage)) \
62 groups_free(group_info); \
65 extern struct group_info init_groups;
66 #ifdef CONFIG_MULTIUSER
67 extern struct group_info *groups_alloc(int);
68 extern void groups_free(struct group_info *);
70 extern int in_group_p(kgid_t);
71 extern int in_egroup_p(kgid_t);
73 static inline void groups_free(struct group_info *group_info)
77 static inline int in_group_p(kgid_t grp)
81 static inline int in_egroup_p(kgid_t grp)
86 extern int set_current_groups(struct group_info *);
87 extern void set_groups(struct cred *, struct group_info *);
88 extern int groups_search(const struct group_info *, kgid_t);
89 extern bool may_setgroups(void);
90 extern void groups_sort(struct group_info *);
92 /* access the groups "array" with this macro */
93 #define GROUP_AT(gi, i) \
94 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
97 * The security context of a task
99 * The parts of the context break down into two categories:
101 * (1) The objective context of a task. These parts are used when some other
102 * task is attempting to affect this one.
104 * (2) The subjective context. These details are used when the task is acting
105 * upon another object, be that a file, a task, a key or whatever.
107 * Note that some members of this structure belong to both categories - the
108 * LSM security pointer for instance.
110 * A task has two security pointers. task->real_cred points to the objective
111 * context that defines that task's actual details. The objective part of this
112 * context is used whenever that task is acted upon.
114 * task->cred points to the subjective context that defines the details of how
115 * that task is going to act upon another object. This may be overridden
116 * temporarily to point to another security context, but normally points to the
117 * same context as task->real_cred.
121 #ifdef CONFIG_DEBUG_CREDENTIALS
122 atomic_t subscribers; /* number of processes subscribed */
125 #define CRED_MAGIC 0x43736564
126 #define CRED_MAGIC_DEAD 0x44656144
128 kuid_t uid; /* real UID of the task */
129 kgid_t gid; /* real GID of the task */
130 kuid_t suid; /* saved UID of the task */
131 kgid_t sgid; /* saved GID of the task */
132 kuid_t euid; /* effective UID of the task */
133 kgid_t egid; /* effective GID of the task */
134 kuid_t fsuid; /* UID for VFS ops */
135 kgid_t fsgid; /* GID for VFS ops */
136 unsigned securebits; /* SUID-less security management */
137 kernel_cap_t cap_inheritable; /* caps our children can inherit */
138 kernel_cap_t cap_permitted; /* caps we're permitted */
139 kernel_cap_t cap_effective; /* caps we can actually use */
140 kernel_cap_t cap_bset; /* capability bounding set */
141 kernel_cap_t cap_ambient; /* Ambient capability set */
143 unsigned char jit_keyring; /* default keyring to attach requested
145 struct key __rcu *session_keyring; /* keyring inherited over fork */
146 struct key *process_keyring; /* keyring private to this process */
147 struct key *thread_keyring; /* keyring private to this thread */
148 struct key *request_key_auth; /* assumed request_key authority */
150 #ifdef CONFIG_SECURITY
151 void *security; /* subjective LSM security */
153 struct user_struct *user; /* real user ID subscription */
154 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
155 struct group_info *group_info; /* supplementary groups for euid/fsgid */
158 int non_rcu; /* Can we skip RCU deletion? */
159 struct rcu_head rcu; /* RCU deletion hook */
163 extern void __put_cred(struct cred *);
164 extern void exit_creds(struct task_struct *);
165 extern int copy_creds(struct task_struct *, unsigned long);
166 extern const struct cred *get_task_cred(struct task_struct *);
167 extern struct cred *cred_alloc_blank(void);
168 extern struct cred *prepare_creds(void);
169 extern struct cred *prepare_exec_creds(void);
170 extern int commit_creds(struct cred *);
171 extern void abort_creds(struct cred *);
172 extern const struct cred *override_creds(const struct cred *);
173 extern void revert_creds(const struct cred *);
174 extern struct cred *prepare_kernel_cred(struct task_struct *);
175 extern int change_create_files_as(struct cred *, struct inode *);
176 extern int set_security_override(struct cred *, u32);
177 extern int set_security_override_from_ctx(struct cred *, const char *);
178 extern int set_create_files_as(struct cred *, struct inode *);
179 extern void __init cred_init(void);
182 * check for validity of credentials
184 #ifdef CONFIG_DEBUG_CREDENTIALS
185 extern void __invalid_creds(const struct cred *, const char *, unsigned);
186 extern void __validate_process_creds(struct task_struct *,
187 const char *, unsigned);
189 extern bool creds_are_invalid(const struct cred *cred);
191 static inline void __validate_creds(const struct cred *cred,
192 const char *file, unsigned line)
194 if (unlikely(creds_are_invalid(cred)))
195 __invalid_creds(cred, file, line);
198 #define validate_creds(cred) \
200 __validate_creds((cred), __FILE__, __LINE__); \
203 #define validate_process_creds() \
205 __validate_process_creds(current, __FILE__, __LINE__); \
208 extern void validate_creds_for_do_exit(struct task_struct *);
210 static inline void validate_creds(const struct cred *cred)
213 static inline void validate_creds_for_do_exit(struct task_struct *tsk)
216 static inline void validate_process_creds(void)
221 static inline bool cap_ambient_invariant_ok(const struct cred *cred)
223 return cap_issubset(cred->cap_ambient,
224 cap_intersect(cred->cap_permitted,
225 cred->cap_inheritable));
229 * get_new_cred - Get a reference on a new set of credentials
230 * @cred: The new credentials to reference
232 * Get a reference on the specified set of new credentials. The caller must
233 * release the reference.
235 static inline struct cred *get_new_cred(struct cred *cred)
237 atomic_inc(&cred->usage);
242 * get_cred - Get a reference on a set of credentials
243 * @cred: The credentials to reference
245 * Get a reference on the specified set of credentials. The caller must
246 * release the reference. If %NULL is passed, it is returned with no action.
248 * This is used to deal with a committed set of credentials. Although the
249 * pointer is const, this will temporarily discard the const and increment the
250 * usage count. The purpose of this is to attempt to catch at compile time the
251 * accidental alteration of a set of credentials that should be considered
254 static inline const struct cred *get_cred(const struct cred *cred)
256 struct cred *nonconst_cred = (struct cred *) cred;
259 validate_creds(cred);
260 nonconst_cred->non_rcu = 0;
261 return get_new_cred(nonconst_cred);
265 * put_cred - Release a reference to a set of credentials
266 * @cred: The credentials to release
268 * Release a reference to a set of credentials, deleting them when the last ref
269 * is released. If %NULL is passed, nothing is done.
271 * This takes a const pointer to a set of credentials because the credentials
272 * on task_struct are attached by const pointers to prevent accidental
273 * alteration of otherwise immutable credential sets.
275 static inline void put_cred(const struct cred *_cred)
277 struct cred *cred = (struct cred *) _cred;
280 validate_creds(cred);
281 if (atomic_dec_and_test(&(cred)->usage))
287 * current_cred - Access the current task's subjective credentials
289 * Access the subjective credentials of the current task. RCU-safe,
290 * since nobody else can modify it.
292 #define current_cred() \
293 rcu_dereference_protected(current->cred, 1)
296 * current_real_cred - Access the current task's objective credentials
298 * Access the objective credentials of the current task. RCU-safe,
299 * since nobody else can modify it.
301 #define current_real_cred() \
302 rcu_dereference_protected(current->real_cred, 1)
305 * __task_cred - Access a task's objective credentials
306 * @task: The task to query
308 * Access the objective credentials of a task. The caller must hold the RCU
311 * The result of this function should not be passed directly to get_cred();
312 * rather get_task_cred() should be used instead.
314 #define __task_cred(task) \
315 rcu_dereference((task)->real_cred)
318 * get_current_cred - Get the current task's subjective credentials
320 * Get the subjective credentials of the current task, pinning them so that
321 * they can't go away. Accessing the current task's credentials directly is
324 #define get_current_cred() \
325 (get_cred(current_cred()))
328 * get_current_user - Get the current task's user_struct
330 * Get the user record of the current task, pinning it so that it can't go
333 #define get_current_user() \
335 struct user_struct *__u; \
336 const struct cred *__cred; \
337 __cred = current_cred(); \
338 __u = get_uid(__cred->user); \
343 * get_current_groups - Get the current task's supplementary group list
345 * Get the supplementary group list of the current task, pinning it so that it
348 #define get_current_groups() \
350 struct group_info *__groups; \
351 const struct cred *__cred; \
352 __cred = current_cred(); \
353 __groups = get_group_info(__cred->group_info); \
357 #define task_cred_xxx(task, xxx) \
359 __typeof__(((struct cred *)NULL)->xxx) ___val; \
361 ___val = __task_cred((task))->xxx; \
366 #define task_uid(task) (task_cred_xxx((task), uid))
367 #define task_euid(task) (task_cred_xxx((task), euid))
369 #define current_cred_xxx(xxx) \
371 current_cred()->xxx; \
374 #define current_uid() (current_cred_xxx(uid))
375 #define current_gid() (current_cred_xxx(gid))
376 #define current_euid() (current_cred_xxx(euid))
377 #define current_egid() (current_cred_xxx(egid))
378 #define current_suid() (current_cred_xxx(suid))
379 #define current_sgid() (current_cred_xxx(sgid))
380 #define current_fsuid() (current_cred_xxx(fsuid))
381 #define current_fsgid() (current_cred_xxx(fsgid))
382 #define current_cap() (current_cred_xxx(cap_effective))
383 #define current_user() (current_cred_xxx(user))
384 #define current_security() (current_cred_xxx(security))
386 extern struct user_namespace init_user_ns;
387 #ifdef CONFIG_USER_NS
388 #define current_user_ns() (current_cred_xxx(user_ns))
390 static inline struct user_namespace *current_user_ns(void)
392 return &init_user_ns;
397 #define current_uid_gid(_uid, _gid) \
399 const struct cred *__cred; \
400 __cred = current_cred(); \
401 *(_uid) = __cred->uid; \
402 *(_gid) = __cred->gid; \
405 #define current_euid_egid(_euid, _egid) \
407 const struct cred *__cred; \
408 __cred = current_cred(); \
409 *(_euid) = __cred->euid; \
410 *(_egid) = __cred->egid; \
413 #define current_fsuid_fsgid(_fsuid, _fsgid) \
415 const struct cred *__cred; \
416 __cred = current_cred(); \
417 *(_fsuid) = __cred->fsuid; \
418 *(_fsgid) = __cred->fsgid; \
421 #endif /* _LINUX_CRED_H */