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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>
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
65extern struct group_info *groups_alloc(int);
Serge Hallyn18b6e042008-10-15 16:38:45 -050066extern struct group_info init_groups;
David Howellsb6dff3e2008-11-14 10:39:16 +110067extern void groups_free(struct group_info *);
68extern int set_current_groups(struct group_info *);
Wang YanQing8f6c5ff2014-04-03 14:48:26 -070069extern void set_groups(struct cred *, struct group_info *);
Eric W. Biedermanae2975b2011-11-14 15:56:38 -080070extern int groups_search(const struct group_info *, kgid_t);
David Howellsb6dff3e2008-11-14 10:39:16 +110071
72/* access the groups "array" with this macro */
73#define GROUP_AT(gi, i) \
74 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
75
Eric W. Biederman72cda3d2012-02-09 09:09:39 -080076extern int in_group_p(kgid_t);
77extern int in_egroup_p(kgid_t);
David Howellsb6dff3e2008-11-14 10:39:16 +110078
79/*
80 * The security context of a task
81 *
82 * The parts of the context break down into two categories:
83 *
84 * (1) The objective context of a task. These parts are used when some other
85 * task is attempting to affect this one.
86 *
87 * (2) The subjective context. These details are used when the task is acting
88 * upon another object, be that a file, a task, a key or whatever.
89 *
90 * Note that some members of this structure belong to both categories - the
91 * LSM security pointer for instance.
92 *
93 * A task has two security pointers. task->real_cred points to the objective
94 * context that defines that task's actual details. The objective part of this
95 * context is used whenever that task is acted upon.
96 *
97 * task->cred points to the subjective context that defines the details of how
98 * that task is going to act upon another object. This may be overridden
99 * temporarily to point to another security context, but normally points to the
100 * same context as task->real_cred.
101 */
102struct cred {
103 atomic_t usage;
David Howellse0e81732009-09-02 09:13:40 +0100104#ifdef CONFIG_DEBUG_CREDENTIALS
105 atomic_t subscribers; /* number of processes subscribed */
106 void *put_addr;
107 unsigned magic;
108#define CRED_MAGIC 0x43736564
109#define CRED_MAGIC_DEAD 0x44656144
110#endif
Eric W. Biederman078de5f2012-02-08 07:00:08 -0800111 kuid_t uid; /* real UID of the task */
112 kgid_t gid; /* real GID of the task */
113 kuid_t suid; /* saved UID of the task */
114 kgid_t sgid; /* saved GID of the task */
115 kuid_t euid; /* effective UID of the task */
116 kgid_t egid; /* effective GID of the task */
117 kuid_t fsuid; /* UID for VFS ops */
118 kgid_t fsgid; /* GID for VFS ops */
David Howellsb6dff3e2008-11-14 10:39:16 +1100119 unsigned securebits; /* SUID-less security management */
120 kernel_cap_t cap_inheritable; /* caps our children can inherit */
121 kernel_cap_t cap_permitted; /* caps we're permitted */
122 kernel_cap_t cap_effective; /* caps we can actually use */
123 kernel_cap_t cap_bset; /* capability bounding set */
124#ifdef CONFIG_KEYS
125 unsigned char jit_keyring; /* default keyring to attach requested
126 * keys to */
David Howells3a505972012-10-02 19:24:29 +0100127 struct key __rcu *session_keyring; /* keyring inherited over fork */
128 struct key *process_keyring; /* keyring private to this process */
David Howellsb6dff3e2008-11-14 10:39:16 +1100129 struct key *thread_keyring; /* keyring private to this thread */
130 struct key *request_key_auth; /* assumed request_key authority */
131#endif
132#ifdef CONFIG_SECURITY
133 void *security; /* subjective LSM security */
134#endif
135 struct user_struct *user; /* real user ID subscription */
Eric W. Biederman0093ccb2011-11-16 21:52:53 -0800136 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
David Howellsb6dff3e2008-11-14 10:39:16 +1100137 struct group_info *group_info; /* supplementary groups for euid/fsgid */
138 struct rcu_head rcu; /* RCU deletion hook */
David Howellsb6dff3e2008-11-14 10:39:16 +1100139};
140
David Howellsf1752ee2008-11-14 10:39:17 +1100141extern void __put_cred(struct cred *);
David Howellse0e81732009-09-02 09:13:40 +0100142extern void exit_creds(struct task_struct *);
David Howellsf1752ee2008-11-14 10:39:17 +1100143extern int copy_creds(struct task_struct *, unsigned long);
David Howellsde09a972010-07-29 12:45:49 +0100144extern const struct cred *get_task_cred(struct task_struct *);
David Howellsee18d642009-09-02 09:14:21 +0100145extern struct cred *cred_alloc_blank(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100146extern struct cred *prepare_creds(void);
David Howellsa6f76f22008-11-14 10:39:24 +1100147extern struct cred *prepare_exec_creds(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100148extern int commit_creds(struct cred *);
149extern void abort_creds(struct cred *);
David Howells3b11a1d2008-11-14 10:39:26 +1100150extern const struct cred *override_creds(const struct cred *);
151extern void revert_creds(const struct cred *);
David Howells3a3b7ce2008-11-14 10:39:28 +1100152extern struct cred *prepare_kernel_cred(struct task_struct *);
153extern int change_create_files_as(struct cred *, struct inode *);
154extern int set_security_override(struct cred *, u32);
155extern int set_security_override_from_ctx(struct cred *, const char *);
156extern int set_create_files_as(struct cred *, struct inode *);
David Howellsd84f4f92008-11-14 10:39:23 +1100157extern void __init cred_init(void);
158
David Howellse0e81732009-09-02 09:13:40 +0100159/*
160 * check for validity of credentials
161 */
162#ifdef CONFIG_DEBUG_CREDENTIALS
163extern void __invalid_creds(const struct cred *, const char *, unsigned);
164extern void __validate_process_creds(struct task_struct *,
165 const char *, unsigned);
166
Andrew Morton74908a02009-09-17 17:47:12 -0700167extern bool creds_are_invalid(const struct cred *cred);
David Howellse0e81732009-09-02 09:13:40 +0100168
169static inline void __validate_creds(const struct cred *cred,
170 const char *file, unsigned line)
171{
172 if (unlikely(creds_are_invalid(cred)))
173 __invalid_creds(cred, file, line);
174}
175
176#define validate_creds(cred) \
177do { \
178 __validate_creds((cred), __FILE__, __LINE__); \
179} while(0)
180
181#define validate_process_creds() \
182do { \
183 __validate_process_creds(current, __FILE__, __LINE__); \
184} while(0)
185
186extern void validate_creds_for_do_exit(struct task_struct *);
187#else
188static inline void validate_creds(const struct cred *cred)
189{
190}
191static inline void validate_creds_for_do_exit(struct task_struct *tsk)
192{
193}
194static inline void validate_process_creds(void)
195{
196}
197#endif
198
David Howellsd84f4f92008-11-14 10:39:23 +1100199/**
200 * get_new_cred - Get a reference on a new set of credentials
201 * @cred: The new credentials to reference
202 *
203 * Get a reference on the specified set of new credentials. The caller must
204 * release the reference.
205 */
206static inline struct cred *get_new_cred(struct cred *cred)
207{
208 atomic_inc(&cred->usage);
209 return cred;
210}
David Howellsf1752ee2008-11-14 10:39:17 +1100211
212/**
213 * get_cred - Get a reference on a set of credentials
214 * @cred: The credentials to reference
215 *
216 * Get a reference on the specified set of credentials. The caller must
217 * release the reference.
David Howells98870ab2008-11-14 10:39:26 +1100218 *
219 * This is used to deal with a committed set of credentials. Although the
220 * pointer is const, this will temporarily discard the const and increment the
221 * usage count. The purpose of this is to attempt to catch at compile time the
222 * accidental alteration of a set of credentials that should be considered
223 * immutable.
David Howellsf1752ee2008-11-14 10:39:17 +1100224 */
David Howellsd84f4f92008-11-14 10:39:23 +1100225static inline const struct cred *get_cred(const struct cred *cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100226{
Paul Menage1c388ad2009-07-17 16:16:18 -0700227 struct cred *nonconst_cred = (struct cred *) cred;
David Howellse0e81732009-09-02 09:13:40 +0100228 validate_creds(cred);
Paul Menage1c388ad2009-07-17 16:16:18 -0700229 return get_new_cred(nonconst_cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100230}
231
232/**
233 * put_cred - Release a reference to a set of credentials
234 * @cred: The credentials to release
235 *
236 * Release a reference to a set of credentials, deleting them when the last ref
237 * is released.
David Howells98870ab2008-11-14 10:39:26 +1100238 *
239 * This takes a const pointer to a set of credentials because the credentials
240 * on task_struct are attached by const pointers to prevent accidental
241 * alteration of otherwise immutable credential sets.
David Howellsf1752ee2008-11-14 10:39:17 +1100242 */
David Howellsc69e8d92008-11-14 10:39:19 +1100243static inline void put_cred(const struct cred *_cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100244{
David Howellsc69e8d92008-11-14 10:39:19 +1100245 struct cred *cred = (struct cred *) _cred;
David Howellsd84f4f92008-11-14 10:39:23 +1100246
David Howellse0e81732009-09-02 09:13:40 +0100247 validate_creds(cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100248 if (atomic_dec_and_test(&(cred)->usage))
249 __put_cred(cred);
250}
251
David Howells86a264a2008-11-14 10:39:18 +1100252/**
David Howells3b11a1d2008-11-14 10:39:26 +1100253 * current_cred - Access the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100254 *
Al Viro32955142011-08-07 18:55:11 +0100255 * Access the subjective credentials of the current task. RCU-safe,
256 * since nobody else can modify it.
David Howells86a264a2008-11-14 10:39:18 +1100257 */
258#define current_cred() \
David Howells27e4e432011-08-08 15:54:53 +0100259 rcu_dereference_protected(current->cred, 1)
David Howells86a264a2008-11-14 10:39:18 +1100260
261/**
David Howells3b11a1d2008-11-14 10:39:26 +1100262 * __task_cred - Access a task's objective credentials
David Howells86a264a2008-11-14 10:39:18 +1100263 * @task: The task to query
264 *
David Howells3b11a1d2008-11-14 10:39:26 +1100265 * Access the objective credentials of a task. The caller must hold the RCU
Oleg Nesterov43e13cc2012-05-31 16:26:16 -0700266 * readlock.
David Howells86a264a2008-11-14 10:39:18 +1100267 *
David Howells8f920542010-07-29 12:45:55 +0100268 * The result of this function should not be passed directly to get_cred();
269 * rather get_task_cred() should be used instead.
David Howells86a264a2008-11-14 10:39:18 +1100270 */
Oleg Nesterov43e13cc2012-05-31 16:26:16 -0700271#define __task_cred(task) \
272 rcu_dereference((task)->real_cred)
David Howells86a264a2008-11-14 10:39:18 +1100273
274/**
David Howells3b11a1d2008-11-14 10:39:26 +1100275 * get_current_cred - Get the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100276 *
David Howells3b11a1d2008-11-14 10:39:26 +1100277 * Get the subjective credentials of the current task, pinning them so that
278 * they can't go away. Accessing the current task's credentials directly is
279 * not permitted.
David Howells86a264a2008-11-14 10:39:18 +1100280 */
281#define get_current_cred() \
282 (get_cred(current_cred()))
283
284/**
285 * get_current_user - Get the current task's user_struct
286 *
287 * Get the user record of the current task, pinning it so that it can't go
288 * away.
289 */
290#define get_current_user() \
291({ \
292 struct user_struct *__u; \
Linus Torvalds638a84392011-08-08 11:33:23 -0700293 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100294 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100295 __u = get_uid(__cred->user); \
296 __u; \
297})
298
299/**
300 * get_current_groups - Get the current task's supplementary group list
301 *
302 * Get the supplementary group list of the current task, pinning it so that it
303 * can't go away.
304 */
305#define get_current_groups() \
306({ \
307 struct group_info *__groups; \
Linus Torvalds638a84392011-08-08 11:33:23 -0700308 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100309 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100310 __groups = get_group_info(__cred->group_info); \
311 __groups; \
312})
313
David Howellsd84f4f92008-11-14 10:39:23 +1100314#define task_cred_xxx(task, xxx) \
315({ \
316 __typeof__(((struct cred *)NULL)->xxx) ___val; \
317 rcu_read_lock(); \
318 ___val = __task_cred((task))->xxx; \
319 rcu_read_unlock(); \
320 ___val; \
David Howells86a264a2008-11-14 10:39:18 +1100321})
322
323#define task_uid(task) (task_cred_xxx((task), uid))
324#define task_euid(task) (task_cred_xxx((task), euid))
325
326#define current_cred_xxx(xxx) \
327({ \
Al Viro32955142011-08-07 18:55:11 +0100328 current_cred()->xxx; \
David Howells86a264a2008-11-14 10:39:18 +1100329})
330
331#define current_uid() (current_cred_xxx(uid))
332#define current_gid() (current_cred_xxx(gid))
333#define current_euid() (current_cred_xxx(euid))
334#define current_egid() (current_cred_xxx(egid))
335#define current_suid() (current_cred_xxx(suid))
336#define current_sgid() (current_cred_xxx(sgid))
337#define current_fsuid() (current_cred_xxx(fsuid))
338#define current_fsgid() (current_cred_xxx(fsgid))
339#define current_cap() (current_cred_xxx(cap_effective))
340#define current_user() (current_cred_xxx(user))
341#define current_security() (current_cred_xxx(security))
342
Eric W. Biederman7e6bd8f2011-11-14 19:29:17 -0800343extern struct user_namespace init_user_ns;
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100344#ifdef CONFIG_USER_NS
Eric Parisf1c84da2012-01-03 12:25:15 -0500345#define current_user_ns() (current_cred_xxx(user_ns))
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100346#else
Eric Parisf1c84da2012-01-03 12:25:15 -0500347#define current_user_ns() (&init_user_ns)
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100348#endif
349
Serge E. Hallyn34867402011-03-23 16:43:17 -0700350
David Howells86a264a2008-11-14 10:39:18 +1100351#define current_uid_gid(_uid, _gid) \
352do { \
353 const struct cred *__cred; \
354 __cred = current_cred(); \
355 *(_uid) = __cred->uid; \
356 *(_gid) = __cred->gid; \
357} while(0)
358
359#define current_euid_egid(_euid, _egid) \
360do { \
361 const struct cred *__cred; \
362 __cred = current_cred(); \
363 *(_euid) = __cred->euid; \
364 *(_egid) = __cred->egid; \
365} while(0)
366
367#define current_fsuid_fsgid(_fsuid, _fsgid) \
368do { \
369 const struct cred *__cred; \
370 __cred = current_cred(); \
371 *(_fsuid) = __cred->fsuid; \
372 *(_fsgid) = __cred->fsgid; \
373} while(0)
374
David Howells9e2b2dc2008-08-13 16:20:04 +0100375#endif /* _LINUX_CRED_H */