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/* Credentials management
*
* 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 must be called with the owning task locked (via task_lock()) when task
* != current. The reason being that the vast majority of callers are looking
* at current->group_info, which can not be changed except by the current task.
* Changing current->group_info requires the task lock, too.
*/
#define get_group_info(group_info) \
do { \
atomic_inc(&(group_info)->usage); \
} while (0)
/**
* 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(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 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 */
#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 */
spinlock_t lock; /* lock for pointer changes */
};
#define get_current_user() (get_uid(current->cred->user))
#define task_uid(task) ((task)->cred->uid)
#define task_gid(task) ((task)->cred->gid)
#define task_euid(task) ((task)->cred->euid)
#define task_egid(task) ((task)->cred->egid)
#define current_uid() (current->cred->uid)
#define current_gid() (current->cred->gid)
#define current_euid() (current->cred->euid)
#define current_egid() (current->cred->egid)
#define current_suid() (current->cred->suid)
#define current_sgid() (current->cred->sgid)
#define current_fsuid() (current->cred->fsuid)
#define current_fsgid() (current->cred->fsgid)
#define current_cap() (current->cred->cap_effective)
#define current_uid_gid(_uid, _gid) \
do { \
*(_uid) = current->cred->uid; \
*(_gid) = current->cred->gid; \
} while(0)
#define current_euid_egid(_uid, _gid) \
do { \
*(_uid) = current->cred->euid; \
*(_gid) = current->cred->egid; \
} while(0)
#define current_fsuid_fsgid(_uid, _gid) \
do { \
*(_uid) = current->cred->fsuid; \
*(_gid) = current->cred->fsgid; \
} while(0)
extern void __put_cred(struct cred *);
extern int copy_creds(struct task_struct *, unsigned long);
/**
* 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.
*/
static inline struct cred *get_cred(struct cred *cred)
{
atomic_inc(&cred->usage);
return 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.
*/
static inline void put_cred(struct cred *cred)
{
if (atomic_dec_and_test(&(cred)->usage))
__put_cred(cred);
}
#endif /* _LINUX_CRED_H */
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