blob: 8b6c083e68a7338c4b5eee9938cc73f40c7faa19 [file] [log] [blame]
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>
Eric W. Biedermanae2975b2011-11-14 15:56:38 -080020#include <linux/uidgid.h>
David Howells9e2b2dc2008-08-13 16:20:04 +010021
David Howellsb6dff3e2008-11-14 10:39:16 +110022struct user_struct;
23struct cred;
David Howells3a3b7ce2008-11-14 10:39:28 +110024struct inode;
David Howells9e2b2dc2008-08-13 16:20:04 +010025
David Howellsb6dff3e2008-11-14 10:39:16 +110026/*
27 * COW Supplementary groups list
28 */
29#define NGROUPS_SMALL 32
Eric W. Biedermanae2975b2011-11-14 15:56:38 -080030#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t)))
David Howellsb6dff3e2008-11-14 10:39:16 +110031
32struct group_info {
33 atomic_t usage;
34 int ngroups;
35 int nblocks;
Eric W. Biedermanae2975b2011-11-14 15:56:38 -080036 kgid_t small_block[NGROUPS_SMALL];
37 kgid_t *blocks[0];
David Howellsb6dff3e2008-11-14 10:39:16 +110038};
39
40/**
41 * get_group_info - Get a reference to a group info structure
42 * @group_info: The group info to reference
43 *
David Howells86a264a2008-11-14 10:39:18 +110044 * This gets a reference to a set of supplementary groups.
45 *
46 * If the caller is accessing a task's credentials, they must hold the RCU read
47 * lock when reading.
David Howellsb6dff3e2008-11-14 10:39:16 +110048 */
David Howells86a264a2008-11-14 10:39:18 +110049static inline struct group_info *get_group_info(struct group_info *gi)
50{
51 atomic_inc(&gi->usage);
52 return gi;
53}
David Howellsb6dff3e2008-11-14 10:39:16 +110054
55/**
56 * put_group_info - Release a reference to a group info structure
57 * @group_info: The group info to release
58 */
59#define put_group_info(group_info) \
60do { \
61 if (atomic_dec_and_test(&(group_info)->usage)) \
62 groups_free(group_info); \
63} while (0)
64
Serge Hallyn18b6e042008-10-15 16:38:45 -050065extern struct group_info init_groups;
Iulia Manda28138932015-04-15 16:16:41 -070066#ifdef CONFIG_MULTIUSER
67extern struct group_info *groups_alloc(int);
David Howellsb6dff3e2008-11-14 10:39:16 +110068extern void groups_free(struct group_info *);
Iulia Manda28138932015-04-15 16:16:41 -070069
70extern int in_group_p(kgid_t);
71extern int in_egroup_p(kgid_t);
72#else
73static inline void groups_free(struct group_info *group_info)
74{
75}
76
77static inline int in_group_p(kgid_t grp)
78{
79 return 1;
80}
81static inline int in_egroup_p(kgid_t grp)
82{
83 return 1;
84}
85#endif
David Howellsb6dff3e2008-11-14 10:39:16 +110086extern int set_current_groups(struct group_info *);
Wang YanQing8f6c5ff2014-04-03 14:48:26 -070087extern void set_groups(struct cred *, struct group_info *);
Eric W. Biedermanae2975b2011-11-14 15:56:38 -080088extern int groups_search(const struct group_info *, kgid_t);
Eric W. Biederman7ff4d902014-12-05 17:19:27 -060089extern bool may_setgroups(void);
David Howellsb6dff3e2008-11-14 10:39:16 +110090
91/* access the groups "array" with this macro */
92#define GROUP_AT(gi, i) \
93 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
94
David Howellsb6dff3e2008-11-14 10:39:16 +110095/*
96 * The security context of a task
97 *
98 * The parts of the context break down into two categories:
99 *
100 * (1) The objective context of a task. These parts are used when some other
101 * task is attempting to affect this one.
102 *
103 * (2) The subjective context. These details are used when the task is acting
104 * upon another object, be that a file, a task, a key or whatever.
105 *
106 * Note that some members of this structure belong to both categories - the
107 * LSM security pointer for instance.
108 *
109 * A task has two security pointers. task->real_cred points to the objective
110 * context that defines that task's actual details. The objective part of this
111 * context is used whenever that task is acted upon.
112 *
113 * task->cred points to the subjective context that defines the details of how
114 * that task is going to act upon another object. This may be overridden
115 * temporarily to point to another security context, but normally points to the
116 * same context as task->real_cred.
117 */
118struct cred {
119 atomic_t usage;
David Howellse0e81732009-09-02 09:13:40 +0100120#ifdef CONFIG_DEBUG_CREDENTIALS
121 atomic_t subscribers; /* number of processes subscribed */
122 void *put_addr;
123 unsigned magic;
124#define CRED_MAGIC 0x43736564
125#define CRED_MAGIC_DEAD 0x44656144
126#endif
Eric W. Biederman078de5f2012-02-08 07:00:08 -0800127 kuid_t uid; /* real UID of the task */
128 kgid_t gid; /* real GID of the task */
129 kuid_t suid; /* saved UID of the task */
130 kgid_t sgid; /* saved GID of the task */
131 kuid_t euid; /* effective UID of the task */
132 kgid_t egid; /* effective GID of the task */
133 kuid_t fsuid; /* UID for VFS ops */
134 kgid_t fsgid; /* GID for VFS ops */
David Howellsb6dff3e2008-11-14 10:39:16 +1100135 unsigned securebits; /* SUID-less security management */
136 kernel_cap_t cap_inheritable; /* caps our children can inherit */
137 kernel_cap_t cap_permitted; /* caps we're permitted */
138 kernel_cap_t cap_effective; /* caps we can actually use */
139 kernel_cap_t cap_bset; /* capability bounding set */
140#ifdef CONFIG_KEYS
141 unsigned char jit_keyring; /* default keyring to attach requested
142 * keys to */
David Howells3a505972012-10-02 19:24:29 +0100143 struct key __rcu *session_keyring; /* keyring inherited over fork */
144 struct key *process_keyring; /* keyring private to this process */
David Howellsb6dff3e2008-11-14 10:39:16 +1100145 struct key *thread_keyring; /* keyring private to this thread */
146 struct key *request_key_auth; /* assumed request_key authority */
147#endif
148#ifdef CONFIG_SECURITY
149 void *security; /* subjective LSM security */
150#endif
151 struct user_struct *user; /* real user ID subscription */
Eric W. Biederman0093ccb2011-11-16 21:52:53 -0800152 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
David Howellsb6dff3e2008-11-14 10:39:16 +1100153 struct group_info *group_info; /* supplementary groups for euid/fsgid */
154 struct rcu_head rcu; /* RCU deletion hook */
David Howellsb6dff3e2008-11-14 10:39:16 +1100155};
156
David Howellsf1752ee2008-11-14 10:39:17 +1100157extern void __put_cred(struct cred *);
David Howellse0e81732009-09-02 09:13:40 +0100158extern void exit_creds(struct task_struct *);
David Howellsf1752ee2008-11-14 10:39:17 +1100159extern int copy_creds(struct task_struct *, unsigned long);
David Howellsde09a972010-07-29 12:45:49 +0100160extern const struct cred *get_task_cred(struct task_struct *);
David Howellsee18d642009-09-02 09:14:21 +0100161extern struct cred *cred_alloc_blank(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100162extern struct cred *prepare_creds(void);
David Howellsa6f76f22008-11-14 10:39:24 +1100163extern struct cred *prepare_exec_creds(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100164extern int commit_creds(struct cred *);
165extern void abort_creds(struct cred *);
David Howells3b11a1d2008-11-14 10:39:26 +1100166extern const struct cred *override_creds(const struct cred *);
167extern void revert_creds(const struct cred *);
David Howells3a3b7ce2008-11-14 10:39:28 +1100168extern struct cred *prepare_kernel_cred(struct task_struct *);
169extern int change_create_files_as(struct cred *, struct inode *);
170extern int set_security_override(struct cred *, u32);
171extern int set_security_override_from_ctx(struct cred *, const char *);
172extern int set_create_files_as(struct cred *, struct inode *);
David Howellsd84f4f92008-11-14 10:39:23 +1100173extern void __init cred_init(void);
174
David Howellse0e81732009-09-02 09:13:40 +0100175/*
176 * check for validity of credentials
177 */
178#ifdef CONFIG_DEBUG_CREDENTIALS
179extern void __invalid_creds(const struct cred *, const char *, unsigned);
180extern void __validate_process_creds(struct task_struct *,
181 const char *, unsigned);
182
Andrew Morton74908a02009-09-17 17:47:12 -0700183extern bool creds_are_invalid(const struct cred *cred);
David Howellse0e81732009-09-02 09:13:40 +0100184
185static inline void __validate_creds(const struct cred *cred,
186 const char *file, unsigned line)
187{
188 if (unlikely(creds_are_invalid(cred)))
189 __invalid_creds(cred, file, line);
190}
191
192#define validate_creds(cred) \
193do { \
194 __validate_creds((cred), __FILE__, __LINE__); \
195} while(0)
196
197#define validate_process_creds() \
198do { \
199 __validate_process_creds(current, __FILE__, __LINE__); \
200} while(0)
201
202extern void validate_creds_for_do_exit(struct task_struct *);
203#else
204static inline void validate_creds(const struct cred *cred)
205{
206}
207static inline void validate_creds_for_do_exit(struct task_struct *tsk)
208{
209}
210static inline void validate_process_creds(void)
211{
212}
213#endif
214
David Howellsd84f4f92008-11-14 10:39:23 +1100215/**
216 * get_new_cred - Get a reference on a new set of credentials
217 * @cred: The new credentials to reference
218 *
219 * Get a reference on the specified set of new credentials. The caller must
220 * release the reference.
221 */
222static inline struct cred *get_new_cred(struct cred *cred)
223{
224 atomic_inc(&cred->usage);
225 return cred;
226}
David Howellsf1752ee2008-11-14 10:39:17 +1100227
228/**
229 * get_cred - Get a reference on a set of credentials
230 * @cred: The credentials to reference
231 *
232 * Get a reference on the specified set of credentials. The caller must
233 * release the reference.
David Howells98870ab2008-11-14 10:39:26 +1100234 *
235 * This is used to deal with a committed set of credentials. Although the
236 * pointer is const, this will temporarily discard the const and increment the
237 * usage count. The purpose of this is to attempt to catch at compile time the
238 * accidental alteration of a set of credentials that should be considered
239 * immutable.
David Howellsf1752ee2008-11-14 10:39:17 +1100240 */
David Howellsd84f4f92008-11-14 10:39:23 +1100241static inline const struct cred *get_cred(const struct cred *cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100242{
Paul Menage1c388ad2009-07-17 16:16:18 -0700243 struct cred *nonconst_cred = (struct cred *) cred;
David Howellse0e81732009-09-02 09:13:40 +0100244 validate_creds(cred);
Paul Menage1c388ad2009-07-17 16:16:18 -0700245 return get_new_cred(nonconst_cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100246}
247
248/**
249 * put_cred - Release a reference to a set of credentials
250 * @cred: The credentials to release
251 *
252 * Release a reference to a set of credentials, deleting them when the last ref
253 * is released.
David Howells98870ab2008-11-14 10:39:26 +1100254 *
255 * This takes a const pointer to a set of credentials because the credentials
256 * on task_struct are attached by const pointers to prevent accidental
257 * alteration of otherwise immutable credential sets.
David Howellsf1752ee2008-11-14 10:39:17 +1100258 */
David Howellsc69e8d92008-11-14 10:39:19 +1100259static inline void put_cred(const struct cred *_cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100260{
David Howellsc69e8d92008-11-14 10:39:19 +1100261 struct cred *cred = (struct cred *) _cred;
David Howellsd84f4f92008-11-14 10:39:23 +1100262
David Howellse0e81732009-09-02 09:13:40 +0100263 validate_creds(cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100264 if (atomic_dec_and_test(&(cred)->usage))
265 __put_cred(cred);
266}
267
David Howells86a264a2008-11-14 10:39:18 +1100268/**
David Howells3b11a1d2008-11-14 10:39:26 +1100269 * current_cred - Access the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100270 *
Al Viro32955142011-08-07 18:55:11 +0100271 * Access the subjective credentials of the current task. RCU-safe,
272 * since nobody else can modify it.
David Howells86a264a2008-11-14 10:39:18 +1100273 */
274#define current_cred() \
David Howells27e4e432011-08-08 15:54:53 +0100275 rcu_dereference_protected(current->cred, 1)
David Howells86a264a2008-11-14 10:39:18 +1100276
277/**
Jeff Laytonae4b8842014-07-15 12:59:36 -0400278 * current_real_cred - Access the current task's objective credentials
279 *
280 * Access the objective credentials of the current task. RCU-safe,
281 * since nobody else can modify it.
282 */
283#define current_real_cred() \
284 rcu_dereference_protected(current->real_cred, 1)
285
286/**
David Howells3b11a1d2008-11-14 10:39:26 +1100287 * __task_cred - Access a task's objective credentials
David Howells86a264a2008-11-14 10:39:18 +1100288 * @task: The task to query
289 *
David Howells3b11a1d2008-11-14 10:39:26 +1100290 * Access the objective credentials of a task. The caller must hold the RCU
Oleg Nesterov43e13cc2012-05-31 16:26:16 -0700291 * readlock.
David Howells86a264a2008-11-14 10:39:18 +1100292 *
David Howells8f920542010-07-29 12:45:55 +0100293 * The result of this function should not be passed directly to get_cred();
294 * rather get_task_cred() should be used instead.
David Howells86a264a2008-11-14 10:39:18 +1100295 */
Oleg Nesterov43e13cc2012-05-31 16:26:16 -0700296#define __task_cred(task) \
297 rcu_dereference((task)->real_cred)
David Howells86a264a2008-11-14 10:39:18 +1100298
299/**
David Howells3b11a1d2008-11-14 10:39:26 +1100300 * get_current_cred - Get the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100301 *
David Howells3b11a1d2008-11-14 10:39:26 +1100302 * Get the subjective credentials of the current task, pinning them so that
303 * they can't go away. Accessing the current task's credentials directly is
304 * not permitted.
David Howells86a264a2008-11-14 10:39:18 +1100305 */
306#define get_current_cred() \
307 (get_cred(current_cred()))
308
309/**
310 * get_current_user - Get the current task's user_struct
311 *
312 * Get the user record of the current task, pinning it so that it can't go
313 * away.
314 */
315#define get_current_user() \
316({ \
317 struct user_struct *__u; \
Linus Torvalds638a84392011-08-08 11:33:23 -0700318 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100319 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100320 __u = get_uid(__cred->user); \
321 __u; \
322})
323
324/**
325 * get_current_groups - Get the current task's supplementary group list
326 *
327 * Get the supplementary group list of the current task, pinning it so that it
328 * can't go away.
329 */
330#define get_current_groups() \
331({ \
332 struct group_info *__groups; \
Linus Torvalds638a84392011-08-08 11:33:23 -0700333 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100334 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100335 __groups = get_group_info(__cred->group_info); \
336 __groups; \
337})
338
David Howellsd84f4f92008-11-14 10:39:23 +1100339#define task_cred_xxx(task, xxx) \
340({ \
341 __typeof__(((struct cred *)NULL)->xxx) ___val; \
342 rcu_read_lock(); \
343 ___val = __task_cred((task))->xxx; \
344 rcu_read_unlock(); \
345 ___val; \
David Howells86a264a2008-11-14 10:39:18 +1100346})
347
348#define task_uid(task) (task_cred_xxx((task), uid))
349#define task_euid(task) (task_cred_xxx((task), euid))
350
351#define current_cred_xxx(xxx) \
352({ \
Al Viro32955142011-08-07 18:55:11 +0100353 current_cred()->xxx; \
David Howells86a264a2008-11-14 10:39:18 +1100354})
355
356#define current_uid() (current_cred_xxx(uid))
357#define current_gid() (current_cred_xxx(gid))
358#define current_euid() (current_cred_xxx(euid))
359#define current_egid() (current_cred_xxx(egid))
360#define current_suid() (current_cred_xxx(suid))
361#define current_sgid() (current_cred_xxx(sgid))
362#define current_fsuid() (current_cred_xxx(fsuid))
363#define current_fsgid() (current_cred_xxx(fsgid))
364#define current_cap() (current_cred_xxx(cap_effective))
365#define current_user() (current_cred_xxx(user))
366#define current_security() (current_cred_xxx(security))
367
Eric W. Biederman7e6bd8f2011-11-14 19:29:17 -0800368extern struct user_namespace init_user_ns;
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100369#ifdef CONFIG_USER_NS
Eric Parisf1c84da2012-01-03 12:25:15 -0500370#define current_user_ns() (current_cred_xxx(user_ns))
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100371#else
Eric Parisf1c84da2012-01-03 12:25:15 -0500372#define current_user_ns() (&init_user_ns)
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100373#endif
374
Serge E. Hallyn34867402011-03-23 16:43:17 -0700375
David Howells86a264a2008-11-14 10:39:18 +1100376#define current_uid_gid(_uid, _gid) \
377do { \
378 const struct cred *__cred; \
379 __cred = current_cred(); \
380 *(_uid) = __cred->uid; \
381 *(_gid) = __cred->gid; \
382} while(0)
383
384#define current_euid_egid(_euid, _egid) \
385do { \
386 const struct cred *__cred; \
387 __cred = current_cred(); \
388 *(_euid) = __cred->euid; \
389 *(_egid) = __cred->egid; \
390} while(0)
391
392#define current_fsuid_fsgid(_fsuid, _fsgid) \
393do { \
394 const struct cred *__cred; \
395 __cred = current_cred(); \
396 *(_fsuid) = __cred->fsuid; \
397 *(_fsgid) = __cred->fsgid; \
398} while(0)
399
David Howells9e2b2dc2008-08-13 16:20:04 +0100400#endif /* _LINUX_CRED_H */