[linux-2.6-block.git] / include / linux / cred.h

/* Credentials management - see Documentation/credentials.txt
 *
 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#ifndef _LINUX_CRED_H
#define _LINUX_CRED_H

#include <linux/capability.h>
#include <linux/key.h>
#include <asm/atomic.h>

struct user_struct;
struct cred;

/*
 * COW Supplementary groups list
 */
#define NGROUPS_SMALL		32
#define NGROUPS_PER_BLOCK	((unsigned int)(PAGE_SIZE / sizeof(gid_t)))

struct group_info {
	atomic_t	usage;
	int		ngroups;
	int		nblocks;
	gid_t		small_block[NGROUPS_SMALL];
	gid_t		*blocks[0];
};

/**
 * get_group_info - Get a reference to a group info structure
 * @group_info: The group info to reference
 *
 * This gets a reference to a set of supplementary groups.
 *
 * If the caller is accessing a task's credentials, they must hold the RCU read
 * lock when reading.
 */
static inline struct group_info *get_group_info(struct group_info *gi)
{
	atomic_inc(&gi->usage);
	return gi;
}

/**
 * put_group_info - Release a reference to a group info structure
 * @group_info: The group info to release
 */
#define put_group_info(group_info)			\
do {							\
	if (atomic_dec_and_test(&(group_info)->usage))	\
		groups_free(group_info);		\
} while (0)

extern struct group_info *groups_alloc(int);
extern void groups_free(struct group_info *);
extern int set_current_groups(struct group_info *);
extern int set_groups(struct cred *, struct group_info *);
extern int groups_search(const struct group_info *, gid_t);

/* access the groups "array" with this macro */
#define GROUP_AT(gi, i) \
	((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])

extern int in_group_p(gid_t);
extern int in_egroup_p(gid_t);

/*
 * The common credentials for a thread group
 * - shared by CLONE_THREAD
 */
#ifdef CONFIG_KEYS
struct thread_group_cred {
	atomic_t	usage;
	pid_t		tgid;			/* thread group process ID */
	spinlock_t	lock;
	struct key	*session_keyring;	/* keyring inherited over fork */
	struct key	*process_keyring;	/* keyring private to this process */
	struct rcu_head	rcu;			/* RCU deletion hook */
};
#endif

/*
 * The security context of a task
 *
 * The parts of the context break down into two categories:
 *
 *  (1) The objective context of a task.  These parts are used when some other
 *	task is attempting to affect this one.
 *
 *  (2) The subjective context.  These details are used when the task is acting
 *	upon another object, be that a file, a task, a key or whatever.
 *
 * Note that some members of this structure belong to both categories - the
 * LSM security pointer for instance.
 *
 * A task has two security pointers.  task->real_cred points to the objective
 * context that defines that task's actual details.  The objective part of this
 * context is used whenever that task is acted upon.
 *
 * task->cred points to the subjective context that defines the details of how
 * that task is going to act upon another object.  This may be overridden
 * temporarily to point to another security context, but normally points to the
 * same context as task->real_cred.
 */
struct cred {
	atomic_t	usage;
	uid_t		uid;		/* real UID of the task */
	gid_t		gid;		/* real GID of the task */
	uid_t		suid;		/* saved UID of the task */
	gid_t		sgid;		/* saved GID of the task */
	uid_t		euid;		/* effective UID of the task */
	gid_t		egid;		/* effective GID of the task */
	uid_t		fsuid;		/* UID for VFS ops */
	gid_t		fsgid;		/* GID for VFS ops */
	unsigned	securebits;	/* SUID-less security management */
	kernel_cap_t	cap_inheritable; /* caps our children can inherit */
	kernel_cap_t	cap_permitted;	/* caps we're permitted */
	kernel_cap_t	cap_effective;	/* caps we can actually use */
	kernel_cap_t	cap_bset;	/* capability bounding set */
#ifdef CONFIG_KEYS
	unsigned char	jit_keyring;	/* default keyring to attach requested
					 * keys to */
	struct key	*thread_keyring; /* keyring private to this thread */
	struct key	*request_key_auth; /* assumed request_key authority */
	struct thread_group_cred *tgcred; /* thread-group shared credentials */
#endif
#ifdef CONFIG_SECURITY
	void		*security;	/* subjective LSM security */
#endif
	struct user_struct *user;	/* real user ID subscription */
	struct group_info *group_info;	/* supplementary groups for euid/fsgid */
	struct rcu_head	rcu;		/* RCU deletion hook */
};

extern void __put_cred(struct cred *);
extern int copy_creds(struct task_struct *, unsigned long);
extern struct cred *prepare_creds(void);
extern struct cred *prepare_exec_creds(void);
extern struct cred *prepare_usermodehelper_creds(void);
extern int commit_creds(struct cred *);
extern void abort_creds(struct cred *);
extern const struct cred *override_creds(const struct cred *) __deprecated;
extern void revert_creds(const struct cred *) __deprecated;
extern void __init cred_init(void);

/**
 * get_new_cred - Get a reference on a new set of credentials
 * @cred: The new credentials to reference
 *
 * Get a reference on the specified set of new credentials.  The caller must
 * release the reference.
 */
static inline struct cred *get_new_cred(struct cred *cred)
{
	atomic_inc(&cred->usage);
	return cred;
}

/**
 * get_cred - Get a reference on a set of credentials
 * @cred: The credentials to reference
 *
 * Get a reference on the specified set of credentials.  The caller must
 * release the reference.
 *
 * This is used to deal with a committed set of credentials.  Although the
 * pointer is const, this will temporarily discard the const and increment the
 * usage count.  The purpose of this is to attempt to catch at compile time the
 * accidental alteration of a set of credentials that should be considered
 * immutable.
 */
static inline const struct cred *get_cred(const struct cred *cred)
{
	return get_new_cred((struct cred *) cred);
}

/**
 * put_cred - Release a reference to a set of credentials
 * @cred: The credentials to release
 *
 * Release a reference to a set of credentials, deleting them when the last ref
 * is released.
 *
 * This takes a const pointer to a set of credentials because the credentials
 * on task_struct are attached by const pointers to prevent accidental
 * alteration of otherwise immutable credential sets.
 */
static inline void put_cred(const struct cred *_cred)
{
	struct cred *cred = (struct cred *) _cred;

	BUG_ON(atomic_read(&(cred)->usage) <= 0);
	if (atomic_dec_and_test(&(cred)->usage))
		__put_cred(cred);
}

/**
 * current_cred - Access the current task's credentials
 *
 * Access the credentials of the current task.
 */
#define current_cred() \
	(current->cred)

/**
 * __task_cred - Access another task's credentials
 * @task: The task to query
 *
 * Access the credentials of another task.  The caller must hold the
 * RCU readlock.
 *
 * The caller must make sure task doesn't go away, either by holding a ref on
 * task or by holding tasklist_lock to prevent it from being unlinked.
 */
#define __task_cred(task) \
	((const struct cred *)(rcu_dereference((task)->cred)))

/**
 * get_task_cred - Get another task's credentials
 * @task: The task to query
 *
 * Get the credentials of a task, pinning them so that they can't go away.
 * Accessing a task's credentials directly is not permitted.
 *
 * The caller must make sure task doesn't go away, either by holding a ref on
 * task or by holding tasklist_lock to prevent it from being unlinked.
 */
#define get_task_cred(task)				\
({							\
	struct cred *__cred;				\
	rcu_read_lock();				\
	__cred = (struct cred *) __task_cred((task));	\
	get_cred(__cred);				\
	rcu_read_unlock();				\
	__cred;						\
})

/**
 * get_current_cred - Get the current task's credentials
 *
 * Get the credentials of the current task, pinning them so that they can't go
 * away.  Accessing the current task's credentials directly is not permitted.
 */
#define get_current_cred()				\
	(get_cred(current_cred()))

/**
 * get_current_user - Get the current task's user_struct
 *
 * Get the user record of the current task, pinning it so that it can't go
 * away.
 */
#define get_current_user()				\
({							\
	struct user_struct *__u;			\
	struct cred *__cred;				\
	__cred = (struct cred *) current_cred();	\
	__u = get_uid(__cred->user);			\
	__u;						\
})

/**
 * get_current_groups - Get the current task's supplementary group list
 *
 * Get the supplementary group list of the current task, pinning it so that it
 * can't go away.
 */
#define get_current_groups()				\
({							\
	struct group_info *__groups;			\
	struct cred *__cred;				\
	__cred = (struct cred *) current_cred();	\
	__groups = get_group_info(__cred->group_info);	\
	__groups;					\
})

#define task_cred_xxx(task, xxx)			\
({							\
	__typeof__(((struct cred *)NULL)->xxx) ___val;	\
	rcu_read_lock();				\
	___val = __task_cred((task))->xxx;		\
	rcu_read_unlock();				\
	___val;						\
})

#define task_uid(task)		(task_cred_xxx((task), uid))
#define task_euid(task)		(task_cred_xxx((task), euid))

#define current_cred_xxx(xxx)			\
({						\
	current->cred->xxx;			\
})

#define current_uid()		(current_cred_xxx(uid))
#define current_gid()		(current_cred_xxx(gid))
#define current_euid()		(current_cred_xxx(euid))
#define current_egid()		(current_cred_xxx(egid))
#define current_suid()		(current_cred_xxx(suid))
#define current_sgid()		(current_cred_xxx(sgid))
#define current_fsuid() 	(current_cred_xxx(fsuid))
#define current_fsgid() 	(current_cred_xxx(fsgid))
#define current_cap()		(current_cred_xxx(cap_effective))
#define current_user()		(current_cred_xxx(user))
#define current_security()	(current_cred_xxx(security))

#define current_uid_gid(_uid, _gid)		\
do {						\
	const struct cred *__cred;		\
	__cred = current_cred();		\
	*(_uid) = __cred->uid;			\
	*(_gid) = __cred->gid;			\
} while(0)

#define current_euid_egid(_euid, _egid)		\
do {						\
	const struct cred *__cred;		\
	__cred = current_cred();		\
	*(_euid) = __cred->euid;		\
	*(_egid) = __cred->egid;		\
} while(0)

#define current_fsuid_fsgid(_fsuid, _fsgid)	\
do {						\
	const struct cred *__cred;		\
	__cred = current_cred();		\
	*(_fsuid) = __cred->fsuid;		\
	*(_fsgid) = __cred->fsgid;		\
} while(0)

#endif /* _LINUX_CRED_H */
Commit	Line	Data
98870ab0	1	/* Credentials management - see Documentation/credentials.txt
9e2b2dc4 DH	2	*
	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
b6dff3ec DH	15	#include <linux/capability.h>
	16	#include <linux/key.h>
	17	#include <asm/atomic.h>
	18
	19	struct user_struct;
	20	struct cred;
	21
	22	/*
	23	* COW Supplementary groups list
	24	*/
	25	#define NGROUPS_SMALL 32
	26	#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t)))
	27
	28	struct group_info {
	29	atomic_t usage;
	30	int ngroups;
	31	int nblocks;
	32	gid_t small_block[NGROUPS_SMALL];
	33	gid_t *blocks[0];
	34	};
	35
	36	/**
	37	* get_group_info - Get a reference to a group info structure
	38	* @group_info: The group info to reference
	39	*
86a264ab DH	40	* This gets a reference to a set of supplementary groups.
	41	*
	42	* If the caller is accessing a task's credentials, they must hold the RCU read
	43	* lock when reading.
b6dff3ec	44	*/
86a264ab DH	45	static inline struct group_info get_group_info(struct group_info gi)
	46	{
	47	atomic_inc(&gi->usage);
	48	return gi;
	49	}
b6dff3ec DH	50
	51	/**
	52	* put_group_info - Release a reference to a group info structure
	53	* @group_info: The group info to release
	54	*/
	55	#define put_group_info(group_info) \
	56	do { \
	57	if (atomic_dec_and_test(&(group_info)->usage)) \
	58	groups_free(group_info); \
	59	} while (0)
	60
	61	extern struct group_info *groups_alloc(int);
	62	extern void groups_free(struct group_info *);
	63	extern int set_current_groups(struct group_info *);
	64	extern int set_groups(struct cred , struct group_info );
86a264ab	65	extern int groups_search(const struct group_info *, gid_t);
b6dff3ec DH	66
	67	/* access the groups "array" with this macro */
	68	#define GROUP_AT(gi, i) \
	69	((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
	70
	71	extern int in_group_p(gid_t);
	72	extern int in_egroup_p(gid_t);
	73
bb952bb9 DH	74	/*
	75	* The common credentials for a thread group
	76	* - shared by CLONE_THREAD
	77	*/
	78	#ifdef CONFIG_KEYS
	79	struct thread_group_cred {
	80	atomic_t usage;
	81	pid_t tgid; /* thread group process ID */
	82	spinlock_t lock;
	83	struct key session_keyring; / keyring inherited over fork */
	84	struct key process_keyring; / keyring private to this process */
	85	struct rcu_head rcu; /* RCU deletion hook */
	86	};
	87	#endif
	88
b6dff3ec DH	89	/*
	90	* The security context of a task
	91	*
	92	* The parts of the context break down into two categories:
	93	*
	94	* (1) The objective context of a task. These parts are used when some other
	95	* task is attempting to affect this one.
	96	*
	97	* (2) The subjective context. These details are used when the task is acting
	98	* upon another object, be that a file, a task, a key or whatever.
	99	*
	100	* Note that some members of this structure belong to both categories - the
	101	* LSM security pointer for instance.
	102	*
	103	* A task has two security pointers. task->real_cred points to the objective
	104	* context that defines that task's actual details. The objective part of this
	105	* context is used whenever that task is acted upon.
	106	*
	107	* task->cred points to the subjective context that defines the details of how
	108	* that task is going to act upon another object. This may be overridden
	109	* temporarily to point to another security context, but normally points to the
	110	* same context as task->real_cred.
	111	*/
	112	struct cred {
	113	atomic_t usage;
	114	uid_t uid; /* real UID of the task */
	115	gid_t gid; /* real GID of the task */
	116	uid_t suid; /* saved UID of the task */
	117	gid_t sgid; /* saved GID of the task */
	118	uid_t euid; /* effective UID of the task */
	119	gid_t egid; /* effective GID of the task */
	120	uid_t fsuid; /* UID for VFS ops */
	121	gid_t fsgid; /* GID for VFS ops */
	122	unsigned securebits; /* SUID-less security management */
	123	kernel_cap_t cap_inheritable; /* caps our children can inherit */
	124	kernel_cap_t cap_permitted; /* caps we're permitted */
	125	kernel_cap_t cap_effective; /* caps we can actually use */
	126	kernel_cap_t cap_bset; /* capability bounding set */
	127	#ifdef CONFIG_KEYS
	128	unsigned char jit_keyring; /* default keyring to attach requested
	129	* keys to */
	130	struct key thread_keyring; / keyring private to this thread */
	131	struct key request_key_auth; / assumed request_key authority */
bb952bb9	132	struct thread_group_cred tgcred; / thread-group shared credentials */
b6dff3ec DH	133	#endif
	134	#ifdef CONFIG_SECURITY
	135	void security; / subjective LSM security */
	136	#endif
	137	struct user_struct user; / real user ID subscription */
	138	struct group_info group_info; / supplementary groups for euid/fsgid */
	139	struct rcu_head rcu; /* RCU deletion hook */
b6dff3ec DH	140	};
b6dff3ec DH	141
f1752eec DH	142	extern void __put_cred(struct cred *);
f1752eec DH	143	extern int copy_creds(struct task_struct *, unsigned long);
d84f4f99	144	extern struct cred *prepare_creds(void);
a6f76f23	145	extern struct cred *prepare_exec_creds(void);
d84f4f99 DH	146	extern struct cred *prepare_usermodehelper_creds(void);
	147	extern int commit_creds(struct cred *);
	148	extern void abort_creds(struct cred *);
	149	extern const struct cred override_creds(const struct cred ) __deprecated;
	150	extern void revert_creds(const struct cred *) __deprecated;
	151	extern void __init cred_init(void);
	152
	153	/**
	154	* get_new_cred - Get a reference on a new set of credentials
	155	* @cred: The new credentials to reference
	156	*
	157	* Get a reference on the specified set of new credentials. The caller must
	158	* release the reference.
	159	*/
	160	static inline struct cred get_new_cred(struct cred cred)
	161	{
	162	atomic_inc(&cred->usage);
	163	return cred;
	164	}
f1752eec DH	165
	166	/**
	167	* get_cred - Get a reference on a set of credentials
	168	* @cred: The credentials to reference
	169	*
	170	* Get a reference on the specified set of credentials. The caller must
	171	* release the reference.
98870ab0 DH	172	*
	173	* This is used to deal with a committed set of credentials. Although the
	174	* pointer is const, this will temporarily discard the const and increment the
	175	* usage count. The purpose of this is to attempt to catch at compile time the
	176	* accidental alteration of a set of credentials that should be considered
	177	* immutable.
f1752eec	178	*/
d84f4f99	179	static inline const struct cred get_cred(const struct cred cred)
f1752eec	180	{
d84f4f99	181	return get_new_cred((struct cred *) cred);
f1752eec DH	182	}
	183
	184	/**
	185	* put_cred - Release a reference to a set of credentials
	186	* @cred: The credentials to release
	187	*
	188	* Release a reference to a set of credentials, deleting them when the last ref
	189	* is released.
98870ab0 DH	190	*
	191	* This takes a const pointer to a set of credentials because the credentials
	192	* on task_struct are attached by const pointers to prevent accidental
	193	* alteration of otherwise immutable credential sets.
f1752eec	194	*/
c69e8d9c	195	static inline void put_cred(const struct cred *_cred)
f1752eec	196	{
c69e8d9c	197	struct cred cred = (struct cred ) _cred;
d84f4f99 DH	198
d84f4f99 DH	199	BUG_ON(atomic_read(&(cred)->usage) <= 0);
f1752eec DH	200	if (atomic_dec_and_test(&(cred)->usage))
	201	__put_cred(cred);
	202	}
	203
86a264ab DH	204	/**
	205	* current_cred - Access the current task's credentials
	206	*
	207	* Access the credentials of the current task.
	208	*/
	209	#define current_cred() \
	210	(current->cred)
	211
	212	/**
	213	* __task_cred - Access another task's credentials
	214	* @task: The task to query
	215	*
	216	* Access the credentials of another task. The caller must hold the
	217	* RCU readlock.
	218	*
	219	* The caller must make sure task doesn't go away, either by holding a ref on
	220	* task or by holding tasklist_lock to prevent it from being unlinked.
	221	*/
	222	#define __task_cred(task) \
	223	((const struct cred *)(rcu_dereference((task)->cred)))
	224
	225	/**
	226	* get_task_cred - Get another task's credentials
	227	* @task: The task to query
	228	*
	229	* Get the credentials of a task, pinning them so that they can't go away.
	230	* Accessing a task's credentials directly is not permitted.
	231	*
	232	* The caller must make sure task doesn't go away, either by holding a ref on
	233	* task or by holding tasklist_lock to prevent it from being unlinked.
	234	*/
	235	#define get_task_cred(task) \
	236	({ \
	237	struct cred *__cred; \
	238	rcu_read_lock(); \
	239	__cred = (struct cred *) __task_cred((task)); \
	240	get_cred(__cred); \
	241	rcu_read_unlock(); \
	242	__cred; \
	243	})
	244
	245	/**
	246	* get_current_cred - Get the current task's credentials
	247	*
	248	* Get the credentials of the current task, pinning them so that they can't go
	249	* away. Accessing the current task's credentials directly is not permitted.
	250	*/
	251	#define get_current_cred() \
	252	(get_cred(current_cred()))
	253
	254	/**
	255	* get_current_user - Get the current task's user_struct
	256	*
	257	* Get the user record of the current task, pinning it so that it can't go
	258	* away.
	259	*/
	260	#define get_current_user() \
	261	({ \
	262	struct user_struct *__u; \
	263	struct cred *__cred; \
	264	__cred = (struct cred *) current_cred(); \
	265	__u = get_uid(__cred->user); \
	266	__u; \
	267	})
268
269	/**
270	* get_current_groups - Get the current task's supplementary group list
271	*
272	* Get the supplementary group list of the current task, pinning it so that it
273	* can't go away.
274	*/
275	#define get_current_groups() \
276	({ \
277	struct group_info *__groups; \
278	struct cred *__cred; \
279	__cred = (struct cred *) current_cred(); \
280	__groups = get_group_info(__cred->group_info); \
281	__groups; \
282	})
283
d84f4f99 DH	284	#define task_cred_xxx(task, xxx) \
	285	({ \
	286	__typeof__(((struct cred *)NULL)->xxx) ___val; \
	287	rcu_read_lock(); \
	288	___val = __task_cred((task))->xxx; \
	289	rcu_read_unlock(); \
	290	___val; \
86a264ab DH	291	})
	292
	293	#define task_uid(task) (task_cred_xxx((task), uid))
	294	#define task_euid(task) (task_cred_xxx((task), euid))
	295
	296	#define current_cred_xxx(xxx) \
	297	({ \
	298	current->cred->xxx; \
	299	})
	300
	301	#define current_uid() (current_cred_xxx(uid))
	302	#define current_gid() (current_cred_xxx(gid))
	303	#define current_euid() (current_cred_xxx(euid))
	304	#define current_egid() (current_cred_xxx(egid))
	305	#define current_suid() (current_cred_xxx(suid))
	306	#define current_sgid() (current_cred_xxx(sgid))
	307	#define current_fsuid() (current_cred_xxx(fsuid))
	308	#define current_fsgid() (current_cred_xxx(fsgid))
	309	#define current_cap() (current_cred_xxx(cap_effective))
	310	#define current_user() (current_cred_xxx(user))
	311	#define current_security() (current_cred_xxx(security))
	312
	313	#define current_uid_gid(_uid, _gid) \
	314	do { \
	315	const struct cred *__cred; \
	316	__cred = current_cred(); \
	317	*(_uid) = __cred->uid; \
	318	*(_gid) = __cred->gid; \
	319	} while(0)
	320
	321	#define current_euid_egid(_euid, _egid) \
	322	do { \
	323	const struct cred *__cred; \
	324	__cred = current_cred(); \
	325	*(_euid) = __cred->euid; \
	326	*(_egid) = __cred->egid; \
	327	} while(0)
	328
	329	#define current_fsuid_fsgid(_fsuid, _fsgid) \
	330	do { \
	331	const struct cred *__cred; \
	332	__cred = current_cred(); \
	333	*(_fsuid) = __cred->fsuid; \
	334	*(_fsgid) = __cred->fsgid; \
	335	} while(0)
	336
9e2b2dc4	337	#endif /* _LINUX_CRED_H */