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Randy Dunlapd410fa42011-05-19 15:59:38 -07001/* Credentials management - see Documentation/security/credentials.txt
David Howells9e2b2dc2008-08-13 16:20:04 +01002 *
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
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.
10 */
11
12#ifndef _LINUX_CRED_H
13#define _LINUX_CRED_H
14
David Howellsb6dff3e2008-11-14 10:39:16 +110015#include <linux/capability.h>
Alexey Dobriyanb2e1fea2009-05-28 14:34:20 -070016#include <linux/init.h>
David Howellsb6dff3e2008-11-14 10:39:16 +110017#include <linux/key.h>
Eric Parised868a52009-09-12 22:54:10 -040018#include <linux/selinux.h>
Arun Sharma600634972011-07-26 16:09:06 -070019#include <linux/atomic.h>
David Howells9e2b2dc2008-08-13 16:20:04 +010020
David Howellsb6dff3e2008-11-14 10:39:16 +110021struct user_struct;
22struct cred;
David Howells3a3b7ce2008-11-14 10:39:28 +110023struct inode;
David Howells9e2b2dc2008-08-13 16:20:04 +010024
David Howellsb6dff3e2008-11-14 10:39:16 +110025/*
26 * COW Supplementary groups list
27 */
28#define NGROUPS_SMALL 32
29#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t)))
30
31struct group_info {
32 atomic_t usage;
33 int ngroups;
34 int nblocks;
35 gid_t small_block[NGROUPS_SMALL];
36 gid_t *blocks[0];
37};
38
39/**
40 * get_group_info - Get a reference to a group info structure
41 * @group_info: The group info to reference
42 *
David Howells86a264a2008-11-14 10:39:18 +110043 * This gets a reference to a set of supplementary groups.
44 *
45 * If the caller is accessing a task's credentials, they must hold the RCU read
46 * lock when reading.
David Howellsb6dff3e2008-11-14 10:39:16 +110047 */
David Howells86a264a2008-11-14 10:39:18 +110048static inline struct group_info *get_group_info(struct group_info *gi)
49{
50 atomic_inc(&gi->usage);
51 return gi;
52}
David Howellsb6dff3e2008-11-14 10:39:16 +110053
54/**
55 * put_group_info - Release a reference to a group info structure
56 * @group_info: The group info to release
57 */
58#define put_group_info(group_info) \
59do { \
60 if (atomic_dec_and_test(&(group_info)->usage)) \
61 groups_free(group_info); \
62} while (0)
63
64extern struct group_info *groups_alloc(int);
Serge Hallyn18b6e042008-10-15 16:38:45 -050065extern struct group_info init_groups;
David Howellsb6dff3e2008-11-14 10:39:16 +110066extern void groups_free(struct group_info *);
67extern int set_current_groups(struct group_info *);
68extern int set_groups(struct cred *, struct group_info *);
David Howells86a264a2008-11-14 10:39:18 +110069extern int groups_search(const struct group_info *, gid_t);
David Howellsb6dff3e2008-11-14 10:39:16 +110070
71/* access the groups "array" with this macro */
72#define GROUP_AT(gi, i) \
73 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
74
75extern int in_group_p(gid_t);
76extern int in_egroup_p(gid_t);
77
78/*
David Howellsbb952bb2008-11-14 10:39:20 +110079 * The common credentials for a thread group
80 * - shared by CLONE_THREAD
81 */
82#ifdef CONFIG_KEYS
83struct thread_group_cred {
84 atomic_t usage;
85 pid_t tgid; /* thread group process ID */
86 spinlock_t lock;
Arnd Bergmanne63ba742010-02-26 18:01:20 +010087 struct key __rcu *session_keyring; /* keyring inherited over fork */
David Howellsbb952bb2008-11-14 10:39:20 +110088 struct key *process_keyring; /* keyring private to this process */
89 struct rcu_head rcu; /* RCU deletion hook */
90};
91#endif
92
93/*
David Howellsb6dff3e2008-11-14 10:39:16 +110094 * The security context of a task
95 *
96 * The parts of the context break down into two categories:
97 *
98 * (1) The objective context of a task. These parts are used when some other
99 * task is attempting to affect this one.
100 *
101 * (2) The subjective context. These details are used when the task is acting
102 * upon another object, be that a file, a task, a key or whatever.
103 *
104 * Note that some members of this structure belong to both categories - the
105 * LSM security pointer for instance.
106 *
107 * A task has two security pointers. task->real_cred points to the objective
108 * context that defines that task's actual details. The objective part of this
109 * context is used whenever that task is acted upon.
110 *
111 * task->cred points to the subjective context that defines the details of how
112 * that task is going to act upon another object. This may be overridden
113 * temporarily to point to another security context, but normally points to the
114 * same context as task->real_cred.
115 */
116struct cred {
117 atomic_t usage;
David Howellse0e81732009-09-02 09:13:40 +0100118#ifdef CONFIG_DEBUG_CREDENTIALS
119 atomic_t subscribers; /* number of processes subscribed */
120 void *put_addr;
121 unsigned magic;
122#define CRED_MAGIC 0x43736564
123#define CRED_MAGIC_DEAD 0x44656144
124#endif
David Howellsb6dff3e2008-11-14 10:39:16 +1100125 uid_t uid; /* real UID of the task */
126 gid_t gid; /* real GID of the task */
127 uid_t suid; /* saved UID of the task */
128 gid_t sgid; /* saved GID of the task */
129 uid_t euid; /* effective UID of the task */
130 gid_t egid; /* effective GID of the task */
131 uid_t fsuid; /* UID for VFS ops */
132 gid_t fsgid; /* GID for VFS ops */
133 unsigned securebits; /* SUID-less security management */
134 kernel_cap_t cap_inheritable; /* caps our children can inherit */
135 kernel_cap_t cap_permitted; /* caps we're permitted */
136 kernel_cap_t cap_effective; /* caps we can actually use */
137 kernel_cap_t cap_bset; /* capability bounding set */
138#ifdef CONFIG_KEYS
139 unsigned char jit_keyring; /* default keyring to attach requested
140 * keys to */
141 struct key *thread_keyring; /* keyring private to this thread */
142 struct key *request_key_auth; /* assumed request_key authority */
David Howellsbb952bb2008-11-14 10:39:20 +1100143 struct thread_group_cred *tgcred; /* thread-group shared credentials */
David Howellsb6dff3e2008-11-14 10:39:16 +1100144#endif
145#ifdef CONFIG_SECURITY
146 void *security; /* subjective LSM security */
147#endif
148 struct user_struct *user; /* real user ID subscription */
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100149 struct user_namespace *user_ns; /* cached user->user_ns */
David Howellsb6dff3e2008-11-14 10:39:16 +1100150 struct group_info *group_info; /* supplementary groups for euid/fsgid */
151 struct rcu_head rcu; /* RCU deletion hook */
David Howellsb6dff3e2008-11-14 10:39:16 +1100152};
153
David Howellsf1752ee2008-11-14 10:39:17 +1100154extern void __put_cred(struct cred *);
David Howellse0e81732009-09-02 09:13:40 +0100155extern void exit_creds(struct task_struct *);
David Howellsf1752ee2008-11-14 10:39:17 +1100156extern int copy_creds(struct task_struct *, unsigned long);
David Howellsde09a972010-07-29 12:45:49 +0100157extern const struct cred *get_task_cred(struct task_struct *);
David Howellsee18d642009-09-02 09:14:21 +0100158extern struct cred *cred_alloc_blank(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100159extern struct cred *prepare_creds(void);
David Howellsa6f76f22008-11-14 10:39:24 +1100160extern struct cred *prepare_exec_creds(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100161extern int commit_creds(struct cred *);
162extern void abort_creds(struct cred *);
David Howells3b11a1d2008-11-14 10:39:26 +1100163extern const struct cred *override_creds(const struct cred *);
164extern void revert_creds(const struct cred *);
David Howells3a3b7ce2008-11-14 10:39:28 +1100165extern struct cred *prepare_kernel_cred(struct task_struct *);
166extern int change_create_files_as(struct cred *, struct inode *);
167extern int set_security_override(struct cred *, u32);
168extern int set_security_override_from_ctx(struct cred *, const char *);
169extern int set_create_files_as(struct cred *, struct inode *);
David Howellsd84f4f92008-11-14 10:39:23 +1100170extern void __init cred_init(void);
171
David Howellse0e81732009-09-02 09:13:40 +0100172/*
173 * check for validity of credentials
174 */
175#ifdef CONFIG_DEBUG_CREDENTIALS
176extern void __invalid_creds(const struct cred *, const char *, unsigned);
177extern void __validate_process_creds(struct task_struct *,
178 const char *, unsigned);
179
Andrew Morton74908a02009-09-17 17:47:12 -0700180extern bool creds_are_invalid(const struct cred *cred);
David Howellse0e81732009-09-02 09:13:40 +0100181
182static inline void __validate_creds(const struct cred *cred,
183 const char *file, unsigned line)
184{
185 if (unlikely(creds_are_invalid(cred)))
186 __invalid_creds(cred, file, line);
187}
188
189#define validate_creds(cred) \
190do { \
191 __validate_creds((cred), __FILE__, __LINE__); \
192} while(0)
193
194#define validate_process_creds() \
195do { \
196 __validate_process_creds(current, __FILE__, __LINE__); \
197} while(0)
198
199extern void validate_creds_for_do_exit(struct task_struct *);
200#else
201static inline void validate_creds(const struct cred *cred)
202{
203}
204static inline void validate_creds_for_do_exit(struct task_struct *tsk)
205{
206}
207static inline void validate_process_creds(void)
208{
209}
210#endif
211
David Howellsd84f4f92008-11-14 10:39:23 +1100212/**
213 * get_new_cred - Get a reference on a new set of credentials
214 * @cred: The new credentials to reference
215 *
216 * Get a reference on the specified set of new credentials. The caller must
217 * release the reference.
218 */
219static inline struct cred *get_new_cred(struct cred *cred)
220{
221 atomic_inc(&cred->usage);
222 return cred;
223}
David Howellsf1752ee2008-11-14 10:39:17 +1100224
225/**
226 * get_cred - Get a reference on a set of credentials
227 * @cred: The credentials to reference
228 *
229 * Get a reference on the specified set of credentials. The caller must
230 * release the reference.
David Howells98870ab2008-11-14 10:39:26 +1100231 *
232 * This is used to deal with a committed set of credentials. Although the
233 * pointer is const, this will temporarily discard the const and increment the
234 * usage count. The purpose of this is to attempt to catch at compile time the
235 * accidental alteration of a set of credentials that should be considered
236 * immutable.
David Howellsf1752ee2008-11-14 10:39:17 +1100237 */
David Howellsd84f4f92008-11-14 10:39:23 +1100238static inline const struct cred *get_cred(const struct cred *cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100239{
Paul Menage1c388ad2009-07-17 16:16:18 -0700240 struct cred *nonconst_cred = (struct cred *) cred;
David Howellse0e81732009-09-02 09:13:40 +0100241 validate_creds(cred);
Paul Menage1c388ad2009-07-17 16:16:18 -0700242 return get_new_cred(nonconst_cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100243}
244
245/**
246 * put_cred - Release a reference to a set of credentials
247 * @cred: The credentials to release
248 *
249 * Release a reference to a set of credentials, deleting them when the last ref
250 * is released.
David Howells98870ab2008-11-14 10:39:26 +1100251 *
252 * This takes a const pointer to a set of credentials because the credentials
253 * on task_struct are attached by const pointers to prevent accidental
254 * alteration of otherwise immutable credential sets.
David Howellsf1752ee2008-11-14 10:39:17 +1100255 */
David Howellsc69e8d92008-11-14 10:39:19 +1100256static inline void put_cred(const struct cred *_cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100257{
David Howellsc69e8d92008-11-14 10:39:19 +1100258 struct cred *cred = (struct cred *) _cred;
David Howellsd84f4f92008-11-14 10:39:23 +1100259
David Howellse0e81732009-09-02 09:13:40 +0100260 validate_creds(cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100261 if (atomic_dec_and_test(&(cred)->usage))
262 __put_cred(cred);
263}
264
David Howells86a264a2008-11-14 10:39:18 +1100265/**
David Howells3b11a1d2008-11-14 10:39:26 +1100266 * current_cred - Access the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100267 *
Al Viro32955142011-08-07 18:55:11 +0100268 * Access the subjective credentials of the current task. RCU-safe,
269 * since nobody else can modify it.
David Howells86a264a2008-11-14 10:39:18 +1100270 */
271#define current_cred() \
David Howells27e4e432011-08-08 15:54:53 +0100272 rcu_dereference_protected(current->cred, 1)
David Howells86a264a2008-11-14 10:39:18 +1100273
274/**
David Howells3b11a1d2008-11-14 10:39:26 +1100275 * __task_cred - Access a task's objective credentials
David Howells86a264a2008-11-14 10:39:18 +1100276 * @task: The task to query
277 *
David Howells3b11a1d2008-11-14 10:39:26 +1100278 * Access the objective credentials of a task. The caller must hold the RCU
David Howells8f920542010-07-29 12:45:55 +0100279 * readlock or the task must be dead and unable to change its own credentials.
David Howells86a264a2008-11-14 10:39:18 +1100280 *
David Howells8f920542010-07-29 12:45:55 +0100281 * The result of this function should not be passed directly to get_cred();
282 * rather get_task_cred() should be used instead.
David Howells86a264a2008-11-14 10:39:18 +1100283 */
David Howells8f920542010-07-29 12:45:55 +0100284#define __task_cred(task) \
285 ({ \
286 const struct task_struct *__t = (task); \
287 rcu_dereference_check(__t->real_cred, \
David Howells8f920542010-07-29 12:45:55 +0100288 task_is_dead(__t)); \
289 })
David Howells86a264a2008-11-14 10:39:18 +1100290
291/**
David Howells3b11a1d2008-11-14 10:39:26 +1100292 * get_current_cred - Get the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100293 *
David Howells3b11a1d2008-11-14 10:39:26 +1100294 * Get the subjective credentials of the current task, pinning them so that
295 * they can't go away. Accessing the current task's credentials directly is
296 * not permitted.
David Howells86a264a2008-11-14 10:39:18 +1100297 */
298#define get_current_cred() \
299 (get_cred(current_cred()))
300
301/**
302 * get_current_user - Get the current task's user_struct
303 *
304 * Get the user record of the current task, pinning it so that it can't go
305 * away.
306 */
307#define get_current_user() \
308({ \
309 struct user_struct *__u; \
Linus Torvalds638a84392011-08-08 11:33:23 -0700310 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100311 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100312 __u = get_uid(__cred->user); \
313 __u; \
314})
315
316/**
317 * get_current_groups - Get the current task's supplementary group list
318 *
319 * Get the supplementary group list of the current task, pinning it so that it
320 * can't go away.
321 */
322#define get_current_groups() \
323({ \
324 struct group_info *__groups; \
Linus Torvalds638a84392011-08-08 11:33:23 -0700325 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100326 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100327 __groups = get_group_info(__cred->group_info); \
328 __groups; \
329})
330
David Howellsd84f4f92008-11-14 10:39:23 +1100331#define task_cred_xxx(task, xxx) \
332({ \
333 __typeof__(((struct cred *)NULL)->xxx) ___val; \
334 rcu_read_lock(); \
335 ___val = __task_cred((task))->xxx; \
336 rcu_read_unlock(); \
337 ___val; \
David Howells86a264a2008-11-14 10:39:18 +1100338})
339
340#define task_uid(task) (task_cred_xxx((task), uid))
341#define task_euid(task) (task_cred_xxx((task), euid))
342
343#define current_cred_xxx(xxx) \
344({ \
Al Viro32955142011-08-07 18:55:11 +0100345 current_cred()->xxx; \
David Howells86a264a2008-11-14 10:39:18 +1100346})
347
348#define current_uid() (current_cred_xxx(uid))
349#define current_gid() (current_cred_xxx(gid))
350#define current_euid() (current_cred_xxx(euid))
351#define current_egid() (current_cred_xxx(egid))
352#define current_suid() (current_cred_xxx(suid))
353#define current_sgid() (current_cred_xxx(sgid))
354#define current_fsuid() (current_cred_xxx(fsuid))
355#define current_fsgid() (current_cred_xxx(fsgid))
356#define current_cap() (current_cred_xxx(cap_effective))
357#define current_user() (current_cred_xxx(user))
358#define current_security() (current_cred_xxx(security))
359
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100360#ifdef CONFIG_USER_NS
361#define current_user_ns() (current_cred_xxx(user_ns))
362#else
363extern struct user_namespace init_user_ns;
364#define current_user_ns() (&init_user_ns)
365#endif
366
Serge E. Hallyn34867402011-03-23 16:43:17 -0700367
David Howells86a264a2008-11-14 10:39:18 +1100368#define current_uid_gid(_uid, _gid) \
369do { \
370 const struct cred *__cred; \
371 __cred = current_cred(); \
372 *(_uid) = __cred->uid; \
373 *(_gid) = __cred->gid; \
374} while(0)
375
376#define current_euid_egid(_euid, _egid) \
377do { \
378 const struct cred *__cred; \
379 __cred = current_cred(); \
380 *(_euid) = __cred->euid; \
381 *(_egid) = __cred->egid; \
382} while(0)
383
384#define current_fsuid_fsgid(_fsuid, _fsgid) \
385do { \
386 const struct cred *__cred; \
387 __cred = current_cred(); \
388 *(_fsuid) = __cred->fsuid; \
389 *(_fsgid) = __cred->fsgid; \
390} while(0)
391
David Howells9e2b2dc2008-08-13 16:20:04 +0100392#endif /* _LINUX_CRED_H */