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/selinux.h>
19 #include <linux/atomic.h>
20 #include <linux/uidgid.h>
21 #include <linux/sched.h>
22 #include <linux/sched/user.h>
28 * COW Supplementary groups list
37 * get_group_info - Get a reference to a group info structure
38 * @group_info: The group info to reference
40 * This gets a reference to a set of supplementary groups.
42 * If the caller is accessing a task's credentials, they must hold the RCU read
45 static inline struct group_info *get_group_info(struct group_info *gi)
47 atomic_inc(&gi->usage);
52 * put_group_info - Release a reference to a group info structure
53 * @group_info: The group info to release
55 #define put_group_info(group_info) \
57 if (atomic_dec_and_test(&(group_info)->usage)) \
58 groups_free(group_info); \
61 extern struct group_info init_groups;
62 #ifdef CONFIG_MULTIUSER
63 extern struct group_info *groups_alloc(int);
64 extern void groups_free(struct group_info *);
66 extern int in_group_p(kgid_t);
67 extern int in_egroup_p(kgid_t);
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)
82 extern int set_current_groups(struct group_info *);
83 extern void set_groups(struct cred *, struct group_info *);
84 extern int groups_search(const struct group_info *, kgid_t);
85 extern bool may_setgroups(void);
86 extern void groups_sort(struct group_info *);
89 * The security context of a task
91 * The parts of the context break down into two categories:
93 * (1) The objective context of a task. These parts are used when some other
94 * task is attempting to affect this one.
96 * (2) The subjective context. These details are used when the task is acting
97 * upon another object, be that a file, a task, a key or whatever.
99 * Note that some members of this structure belong to both categories - the
100 * LSM security pointer for instance.
102 * A task has two security pointers. task->real_cred points to the objective
103 * context that defines that task's actual details. The objective part of this
104 * context is used whenever that task is acted upon.
106 * task->cred points to the subjective context that defines the details of how
107 * that task is going to act upon another object. This may be overridden
108 * temporarily to point to another security context, but normally points to the
109 * same context as task->real_cred.
113 #ifdef CONFIG_DEBUG_CREDENTIALS
114 atomic_t subscribers; /* number of processes subscribed */
117 #define CRED_MAGIC 0x43736564
118 #define CRED_MAGIC_DEAD 0x44656144
120 kuid_t uid; /* real UID of the task */
121 kgid_t gid; /* real GID of the task */
122 kuid_t suid; /* saved UID of the task */
123 kgid_t sgid; /* saved GID of the task */
124 kuid_t euid; /* effective UID of the task */
125 kgid_t egid; /* effective GID of the task */
126 kuid_t fsuid; /* UID for VFS ops */
127 kgid_t fsgid; /* GID for VFS ops */
128 unsigned securebits; /* SUID-less security management */
129 kernel_cap_t cap_inheritable; /* caps our children can inherit */
130 kernel_cap_t cap_permitted; /* caps we're permitted */
131 kernel_cap_t cap_effective; /* caps we can actually use */
132 kernel_cap_t cap_bset; /* capability bounding set */
133 kernel_cap_t cap_ambient; /* Ambient capability set */
135 unsigned char jit_keyring; /* default keyring to attach requested
137 struct key __rcu *session_keyring; /* keyring inherited over fork */
138 struct key *process_keyring; /* keyring private to this process */
139 struct key *thread_keyring; /* keyring private to this thread */
140 struct key *request_key_auth; /* assumed request_key authority */
142 #ifdef CONFIG_SECURITY
143 void *security; /* subjective LSM security */
145 struct user_struct *user; /* real user ID subscription */
146 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
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 void __init cred_init(void);
174 * check for validity of credentials
176 #ifdef CONFIG_DEBUG_CREDENTIALS
177 extern void __invalid_creds(const struct cred *, const char *, unsigned);
178 extern void __validate_process_creds(struct task_struct *,
179 const char *, unsigned);
181 extern bool creds_are_invalid(const struct cred *cred);
183 static inline void __validate_creds(const struct cred *cred,
184 const char *file, unsigned line)
186 if (unlikely(creds_are_invalid(cred)))
187 __invalid_creds(cred, file, line);
190 #define validate_creds(cred) \
192 __validate_creds((cred), __FILE__, __LINE__); \
195 #define validate_process_creds() \
197 __validate_process_creds(current, __FILE__, __LINE__); \
200 extern void validate_creds_for_do_exit(struct task_struct *);
202 static inline void validate_creds(const struct cred *cred)
205 static inline void validate_creds_for_do_exit(struct task_struct *tsk)
208 static inline void validate_process_creds(void)
213 static inline bool cap_ambient_invariant_ok(const struct cred *cred)
215 return cap_issubset(cred->cap_ambient,
216 cap_intersect(cred->cap_permitted,
217 cred->cap_inheritable));
221 * get_new_cred - Get a reference on a new set of credentials
222 * @cred: The new credentials to reference
224 * Get a reference on the specified set of new credentials. The caller must
225 * release the reference.
227 static inline struct cred *get_new_cred(struct cred *cred)
229 atomic_inc(&cred->usage);
234 * get_cred - Get a reference on a set of credentials
235 * @cred: The credentials to reference
237 * Get a reference on the specified set of credentials. The caller must
238 * release the reference. If %NULL is passed, it is returned with no action.
240 * This is used to deal with a committed set of credentials. Although the
241 * pointer is const, this will temporarily discard the const and increment the
242 * usage count. The purpose of this is to attempt to catch at compile time the
243 * accidental alteration of a set of credentials that should be considered
246 static inline const struct cred *get_cred(const struct cred *cred)
248 struct cred *nonconst_cred = (struct cred *) cred;
251 validate_creds(cred);
252 nonconst_cred->non_rcu = 0;
253 return get_new_cred(nonconst_cred);
257 * put_cred - Release a reference to a set of credentials
258 * @cred: The credentials to release
260 * Release a reference to a set of credentials, deleting them when the last ref
261 * is released. If %NULL is passed, nothing is done.
263 * This takes a const pointer to a set of credentials because the credentials
264 * on task_struct are attached by const pointers to prevent accidental
265 * alteration of otherwise immutable credential sets.
267 static inline void put_cred(const struct cred *_cred)
269 struct cred *cred = (struct cred *) _cred;
272 validate_creds(cred);
273 if (atomic_dec_and_test(&(cred)->usage))
279 * current_cred - Access the current task's subjective credentials
281 * Access the subjective credentials of the current task. RCU-safe,
282 * since nobody else can modify it.
284 #define current_cred() \
285 rcu_dereference_protected(current->cred, 1)
288 * current_real_cred - Access the current task's objective credentials
290 * Access the objective credentials of the current task. RCU-safe,
291 * since nobody else can modify it.
293 #define current_real_cred() \
294 rcu_dereference_protected(current->real_cred, 1)
297 * __task_cred - Access a task's objective credentials
298 * @task: The task to query
300 * Access the objective credentials of a task. The caller must hold the RCU
303 * The result of this function should not be passed directly to get_cred();
304 * rather get_task_cred() should be used instead.
306 #define __task_cred(task) \
307 rcu_dereference((task)->real_cred)
310 * get_current_cred - Get the current task's subjective credentials
312 * Get the subjective credentials of the current task, pinning them so that
313 * they can't go away. Accessing the current task's credentials directly is
316 #define get_current_cred() \
317 (get_cred(current_cred()))
320 * get_current_user - Get the current task's user_struct
322 * Get the user record of the current task, pinning it so that it can't go
325 #define get_current_user() \
327 struct user_struct *__u; \
328 const struct cred *__cred; \
329 __cred = current_cred(); \
330 __u = get_uid(__cred->user); \
335 * get_current_groups - Get the current task's supplementary group list
337 * Get the supplementary group list of the current task, pinning it so that it
340 #define get_current_groups() \
342 struct group_info *__groups; \
343 const struct cred *__cred; \
344 __cred = current_cred(); \
345 __groups = get_group_info(__cred->group_info); \
349 #define task_cred_xxx(task, xxx) \
351 __typeof__(((struct cred *)NULL)->xxx) ___val; \
353 ___val = __task_cred((task))->xxx; \
358 #define task_uid(task) (task_cred_xxx((task), uid))
359 #define task_euid(task) (task_cred_xxx((task), euid))
361 #define current_cred_xxx(xxx) \
363 current_cred()->xxx; \
366 #define current_uid() (current_cred_xxx(uid))
367 #define current_gid() (current_cred_xxx(gid))
368 #define current_euid() (current_cred_xxx(euid))
369 #define current_egid() (current_cred_xxx(egid))
370 #define current_suid() (current_cred_xxx(suid))
371 #define current_sgid() (current_cred_xxx(sgid))
372 #define current_fsuid() (current_cred_xxx(fsuid))
373 #define current_fsgid() (current_cred_xxx(fsgid))
374 #define current_cap() (current_cred_xxx(cap_effective))
375 #define current_user() (current_cred_xxx(user))
376 #define current_security() (current_cred_xxx(security))
378 extern struct user_namespace init_user_ns;
379 #ifdef CONFIG_USER_NS
380 #define current_user_ns() (current_cred_xxx(user_ns))
382 static inline struct user_namespace *current_user_ns(void)
384 return &init_user_ns;
389 #define current_uid_gid(_uid, _gid) \
391 const struct cred *__cred; \
392 __cred = current_cred(); \
393 *(_uid) = __cred->uid; \
394 *(_gid) = __cred->gid; \
397 #define current_euid_egid(_euid, _egid) \
399 const struct cred *__cred; \
400 __cred = current_cred(); \
401 *(_euid) = __cred->euid; \
402 *(_egid) = __cred->egid; \
405 #define current_fsuid_fsgid(_fsuid, _fsgid) \
407 const struct cred *__cred; \
408 __cred = current_cred(); \
409 *(_fsuid) = __cred->fsuid; \
410 *(_fsgid) = __cred->fsgid; \
413 #endif /* _LINUX_CRED_H */