/* Credentials management - see Documentation/credentials.txt

#include <linux/capability.h>

#include <linux/key.h>

#include <asm/atomic.h>

struct user_struct;

struct cred;

struct inode;

/*

 * 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 struct group_info init_groups;

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 *);

extern void revert_creds(const struct cred *);

extern struct cred *prepare_kernel_cred(struct task_struct *);

extern int change_create_files_as(struct cred *, struct inode *);

extern int set_security_override(struct cred *, u32);

extern int set_security_override_from_ctx(struct cred *, const char *);

extern int set_create_files_as(struct cred *, struct inode *);

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 subjective credentials

 *

 * Access the subjective credentials of the current task.

 */

#define current_cred() \

	(current->cred)

/**

 * __task_cred - Access a task's objective credentials

 * @task: The task to query

 *

 * Access the objective credentials of a 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)->real_cred)))

/**

 * get_task_cred - Get another task's objective credentials

 * @task: The task to query

 *

 * Get the objective 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 subjective credentials

 *

 * Get the subjective 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_user_ns()	(current_cred_xxx(user)->user_ns)

#define current_security()	(current_cred_xxx(security))

	const struct cred *__cred;		\

	__cred = current_cred();		\

	*(_uid) = __cred->uid;			\

	*(_gid) = __cred->gid;			\

#define current_euid_egid(_euid, _egid)		\

	const struct cred *__cred;		\

	__cred = current_cred();		\

	*(_euid) = __cred->euid;		\

	*(_egid) = __cred->egid;		\

#define current_fsuid_fsgid(_fsuid, _fsgid)	\

	const struct cred *__cred;		\

	__cred = current_cred();		\

	*(_fsuid) = __cred->fsuid;		\

	*(_fsgid) = __cred->fsgid;		\