blob: 8d70e1361ecd0ee01b4f11380623ada6a7751888 [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 */
Andy Lutomirski58319052015-09-04 15:42:45 -0700140 kernel_cap_t cap_ambient; /* Ambient capability set */
David Howellsb6dff3e2008-11-14 10:39:16 +1100141#ifdef CONFIG_KEYS
142 unsigned char jit_keyring; /* default keyring to attach requested
143 * keys to */
David Howells3a505972012-10-02 19:24:29 +0100144 struct key __rcu *session_keyring; /* keyring inherited over fork */
145 struct key *process_keyring; /* keyring private to this process */
David Howellsb6dff3e2008-11-14 10:39:16 +1100146 struct key *thread_keyring; /* keyring private to this thread */
147 struct key *request_key_auth; /* assumed request_key authority */
148#endif
149#ifdef CONFIG_SECURITY
150 void *security; /* subjective LSM security */
151#endif
152 struct user_struct *user; /* real user ID subscription */
Eric W. Biederman0093ccb2011-11-16 21:52:53 -0800153 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
David Howellsb6dff3e2008-11-14 10:39:16 +1100154 struct group_info *group_info; /* supplementary groups for euid/fsgid */
155 struct rcu_head rcu; /* RCU deletion hook */
David Howellsb6dff3e2008-11-14 10:39:16 +1100156};
157
David Howellsf1752ee2008-11-14 10:39:17 +1100158extern void __put_cred(struct cred *);
David Howellse0e81732009-09-02 09:13:40 +0100159extern void exit_creds(struct task_struct *);
David Howellsf1752ee2008-11-14 10:39:17 +1100160extern int copy_creds(struct task_struct *, unsigned long);
David Howellsde09a972010-07-29 12:45:49 +0100161extern const struct cred *get_task_cred(struct task_struct *);
David Howellsee18d642009-09-02 09:14:21 +0100162extern struct cred *cred_alloc_blank(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100163extern struct cred *prepare_creds(void);
David Howellsa6f76f22008-11-14 10:39:24 +1100164extern struct cred *prepare_exec_creds(void);
David Howellsd84f4f92008-11-14 10:39:23 +1100165extern int commit_creds(struct cred *);
166extern void abort_creds(struct cred *);
David Howells3b11a1d2008-11-14 10:39:26 +1100167extern const struct cred *override_creds(const struct cred *);
168extern void revert_creds(const struct cred *);
David Howells3a3b7ce2008-11-14 10:39:28 +1100169extern struct cred *prepare_kernel_cred(struct task_struct *);
170extern int change_create_files_as(struct cred *, struct inode *);
171extern int set_security_override(struct cred *, u32);
172extern int set_security_override_from_ctx(struct cred *, const char *);
173extern int set_create_files_as(struct cred *, struct inode *);
David Howellsd84f4f92008-11-14 10:39:23 +1100174extern void __init cred_init(void);
175
David Howellse0e81732009-09-02 09:13:40 +0100176/*
177 * check for validity of credentials
178 */
179#ifdef CONFIG_DEBUG_CREDENTIALS
180extern void __invalid_creds(const struct cred *, const char *, unsigned);
181extern void __validate_process_creds(struct task_struct *,
182 const char *, unsigned);
183
Andrew Morton74908a02009-09-17 17:47:12 -0700184extern bool creds_are_invalid(const struct cred *cred);
David Howellse0e81732009-09-02 09:13:40 +0100185
186static inline void __validate_creds(const struct cred *cred,
187 const char *file, unsigned line)
188{
189 if (unlikely(creds_are_invalid(cred)))
190 __invalid_creds(cred, file, line);
191}
192
193#define validate_creds(cred) \
194do { \
195 __validate_creds((cred), __FILE__, __LINE__); \
196} while(0)
197
198#define validate_process_creds() \
199do { \
200 __validate_process_creds(current, __FILE__, __LINE__); \
201} while(0)
202
203extern void validate_creds_for_do_exit(struct task_struct *);
204#else
205static inline void validate_creds(const struct cred *cred)
206{
207}
208static inline void validate_creds_for_do_exit(struct task_struct *tsk)
209{
210}
211static inline void validate_process_creds(void)
212{
213}
214#endif
215
Andy Lutomirski58319052015-09-04 15:42:45 -0700216static inline bool cap_ambient_invariant_ok(const struct cred *cred)
217{
218 return cap_issubset(cred->cap_ambient,
219 cap_intersect(cred->cap_permitted,
220 cred->cap_inheritable));
221}
222
David Howellsd84f4f92008-11-14 10:39:23 +1100223/**
224 * get_new_cred - Get a reference on a new set of credentials
225 * @cred: The new credentials to reference
226 *
227 * Get a reference on the specified set of new credentials. The caller must
228 * release the reference.
229 */
230static inline struct cred *get_new_cred(struct cred *cred)
231{
232 atomic_inc(&cred->usage);
233 return cred;
234}
David Howellsf1752ee2008-11-14 10:39:17 +1100235
236/**
237 * get_cred - Get a reference on a set of credentials
238 * @cred: The credentials to reference
239 *
240 * Get a reference on the specified set of credentials. The caller must
241 * release the reference.
David Howells98870ab2008-11-14 10:39:26 +1100242 *
243 * This is used to deal with a committed set of credentials. Although the
244 * pointer is const, this will temporarily discard the const and increment the
245 * usage count. The purpose of this is to attempt to catch at compile time the
246 * accidental alteration of a set of credentials that should be considered
247 * immutable.
David Howellsf1752ee2008-11-14 10:39:17 +1100248 */
David Howellsd84f4f92008-11-14 10:39:23 +1100249static inline const struct cred *get_cred(const struct cred *cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100250{
Paul Menage1c388ad2009-07-17 16:16:18 -0700251 struct cred *nonconst_cred = (struct cred *) cred;
David Howellse0e81732009-09-02 09:13:40 +0100252 validate_creds(cred);
Paul Menage1c388ad2009-07-17 16:16:18 -0700253 return get_new_cred(nonconst_cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100254}
255
256/**
257 * put_cred - Release a reference to a set of credentials
258 * @cred: The credentials to release
259 *
260 * Release a reference to a set of credentials, deleting them when the last ref
261 * is released.
David Howells98870ab2008-11-14 10:39:26 +1100262 *
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.
David Howellsf1752ee2008-11-14 10:39:17 +1100266 */
David Howellsc69e8d92008-11-14 10:39:19 +1100267static inline void put_cred(const struct cred *_cred)
David Howellsf1752ee2008-11-14 10:39:17 +1100268{
David Howellsc69e8d92008-11-14 10:39:19 +1100269 struct cred *cred = (struct cred *) _cred;
David Howellsd84f4f92008-11-14 10:39:23 +1100270
David Howellse0e81732009-09-02 09:13:40 +0100271 validate_creds(cred);
David Howellsf1752ee2008-11-14 10:39:17 +1100272 if (atomic_dec_and_test(&(cred)->usage))
273 __put_cred(cred);
274}
275
David Howells86a264a2008-11-14 10:39:18 +1100276/**
David Howells3b11a1d2008-11-14 10:39:26 +1100277 * current_cred - Access the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100278 *
Al Viro32955142011-08-07 18:55:11 +0100279 * Access the subjective credentials of the current task. RCU-safe,
280 * since nobody else can modify it.
David Howells86a264a2008-11-14 10:39:18 +1100281 */
282#define current_cred() \
David Howells27e4e432011-08-08 15:54:53 +0100283 rcu_dereference_protected(current->cred, 1)
David Howells86a264a2008-11-14 10:39:18 +1100284
285/**
Jeff Laytonae4b8842014-07-15 12:59:36 -0400286 * current_real_cred - Access the current task's objective credentials
287 *
288 * Access the objective credentials of the current task. RCU-safe,
289 * since nobody else can modify it.
290 */
291#define current_real_cred() \
292 rcu_dereference_protected(current->real_cred, 1)
293
294/**
David Howells3b11a1d2008-11-14 10:39:26 +1100295 * __task_cred - Access a task's objective credentials
David Howells86a264a2008-11-14 10:39:18 +1100296 * @task: The task to query
297 *
David Howells3b11a1d2008-11-14 10:39:26 +1100298 * Access the objective credentials of a task. The caller must hold the RCU
Oleg Nesterov43e13cc2012-05-31 16:26:16 -0700299 * readlock.
David Howells86a264a2008-11-14 10:39:18 +1100300 *
David Howells8f920542010-07-29 12:45:55 +0100301 * The result of this function should not be passed directly to get_cred();
302 * rather get_task_cred() should be used instead.
David Howells86a264a2008-11-14 10:39:18 +1100303 */
Oleg Nesterov43e13cc2012-05-31 16:26:16 -0700304#define __task_cred(task) \
305 rcu_dereference((task)->real_cred)
David Howells86a264a2008-11-14 10:39:18 +1100306
307/**
David Howells3b11a1d2008-11-14 10:39:26 +1100308 * get_current_cred - Get the current task's subjective credentials
David Howells86a264a2008-11-14 10:39:18 +1100309 *
David Howells3b11a1d2008-11-14 10:39:26 +1100310 * Get the subjective credentials of the current task, pinning them so that
311 * they can't go away. Accessing the current task's credentials directly is
312 * not permitted.
David Howells86a264a2008-11-14 10:39:18 +1100313 */
314#define get_current_cred() \
315 (get_cred(current_cred()))
316
317/**
318 * get_current_user - Get the current task's user_struct
319 *
320 * Get the user record of the current task, pinning it so that it can't go
321 * away.
322 */
323#define get_current_user() \
324({ \
325 struct user_struct *__u; \
Linus Torvalds638a8432011-08-08 11:33:23 -0700326 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100327 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100328 __u = get_uid(__cred->user); \
329 __u; \
330})
331
332/**
333 * get_current_groups - Get the current task's supplementary group list
334 *
335 * Get the supplementary group list of the current task, pinning it so that it
336 * can't go away.
337 */
338#define get_current_groups() \
339({ \
340 struct group_info *__groups; \
Linus Torvalds638a8432011-08-08 11:33:23 -0700341 const struct cred *__cred; \
Al Viro32955142011-08-07 18:55:11 +0100342 __cred = current_cred(); \
David Howells86a264a2008-11-14 10:39:18 +1100343 __groups = get_group_info(__cred->group_info); \
344 __groups; \
345})
346
David Howellsd84f4f92008-11-14 10:39:23 +1100347#define task_cred_xxx(task, xxx) \
348({ \
349 __typeof__(((struct cred *)NULL)->xxx) ___val; \
350 rcu_read_lock(); \
351 ___val = __task_cred((task))->xxx; \
352 rcu_read_unlock(); \
353 ___val; \
David Howells86a264a2008-11-14 10:39:18 +1100354})
355
356#define task_uid(task) (task_cred_xxx((task), uid))
357#define task_euid(task) (task_cred_xxx((task), euid))
358
359#define current_cred_xxx(xxx) \
360({ \
Al Viro32955142011-08-07 18:55:11 +0100361 current_cred()->xxx; \
David Howells86a264a2008-11-14 10:39:18 +1100362})
363
364#define current_uid() (current_cred_xxx(uid))
365#define current_gid() (current_cred_xxx(gid))
366#define current_euid() (current_cred_xxx(euid))
367#define current_egid() (current_cred_xxx(egid))
368#define current_suid() (current_cred_xxx(suid))
369#define current_sgid() (current_cred_xxx(sgid))
370#define current_fsuid() (current_cred_xxx(fsuid))
371#define current_fsgid() (current_cred_xxx(fsgid))
372#define current_cap() (current_cred_xxx(cap_effective))
373#define current_user() (current_cred_xxx(user))
374#define current_security() (current_cred_xxx(security))
375
Eric W. Biederman7e6bd8f2011-11-14 19:29:17 -0800376extern struct user_namespace init_user_ns;
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100377#ifdef CONFIG_USER_NS
Eric Parisf1c84da2012-01-03 12:25:15 -0500378#define current_user_ns() (current_cred_xxx(user_ns))
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100379#else
Eric Parisf1c84da2012-01-03 12:25:15 -0500380#define current_user_ns() (&init_user_ns)
Serge E. Hallyn47a150e2011-05-13 04:27:54 +0100381#endif
382
Serge E. Hallyn34867402011-03-23 16:43:17 -0700383
David Howells86a264a2008-11-14 10:39:18 +1100384#define current_uid_gid(_uid, _gid) \
385do { \
386 const struct cred *__cred; \
387 __cred = current_cred(); \
388 *(_uid) = __cred->uid; \
389 *(_gid) = __cred->gid; \
390} while(0)
391
392#define current_euid_egid(_euid, _egid) \
393do { \
394 const struct cred *__cred; \
395 __cred = current_cred(); \
396 *(_euid) = __cred->euid; \
397 *(_egid) = __cred->egid; \
398} while(0)
399
400#define current_fsuid_fsgid(_fsuid, _fsgid) \
401do { \
402 const struct cred *__cred; \
403 __cred = current_cred(); \
404 *(_fsuid) = __cred->fsuid; \
405 *(_fsgid) = __cred->fsgid; \
406} while(0)
407
David Howells9e2b2dc2008-08-13 16:20:04 +0100408#endif /* _LINUX_CRED_H */