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/* Credentials management - see Documentation/security/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/init.h>
#include <linux/key.h>
#include <linux/selinux.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 __rcu *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;
#ifdef CONFIG_DEBUG_CREDENTIALS
atomic_t subscribers; /* number of processes subscribed */
void *put_addr;
unsigned magic;
#define CRED_MAGIC 0x43736564
#define CRED_MAGIC_DEAD 0x44656144
#endif
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 user_namespace *user_ns; /* cached user->user_ns */
struct group_info *group_info; /* supplementary groups for euid/fsgid */
struct rcu_head rcu; /* RCU deletion hook */
};
extern void __put_cred(struct cred *);
extern void exit_creds(struct task_struct *);
extern int copy_creds(struct task_struct *, unsigned long);
extern const struct cred *get_task_cred(struct task_struct *);
extern struct cred *cred_alloc_blank(void);
extern struct cred *prepare_creds(void);
extern struct cred *prepare_exec_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);
/*
* check for validity of credentials
*/
#ifdef CONFIG_DEBUG_CREDENTIALS
extern void __invalid_creds(const struct cred *, const char *, unsigned);
extern void __validate_process_creds(struct task_struct *,
const char *, unsigned);
extern bool creds_are_invalid(const struct cred *cred);
static inline void __validate_creds(const struct cred *cred,
const char *file, unsigned line)
{
if (unlikely(creds_are_invalid(cred)))
__invalid_creds(cred, file, line);
}
#define validate_creds(cred) \
do { \
__validate_creds((cred), __FILE__, __LINE__); \
} while(0)
#define validate_process_creds() \
do { \
__validate_process_creds(current, __FILE__, __LINE__); \
} while(0)
extern void validate_creds_for_do_exit(struct task_struct *);
#else
static inline void validate_creds(const struct cred *cred)
{
}
static inline void validate_creds_for_do_exit(struct task_struct *tsk)
{
}
static inline void validate_process_creds(void)
{
}
#endif
/**
* 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)
{
struct cred *nonconst_cred = (struct cred *) cred;
validate_creds(cred);
return get_new_cred(nonconst_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;
validate_creds(cred);
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 or the task must be dead and unable to change its own credentials.
*
* The result of this function should not be passed directly to get_cred();
* rather get_task_cred() should be used instead.
*/
#define __task_cred(task) \
({ \
const struct task_struct *__t = (task); \
rcu_dereference_check(__t->real_cred, \
rcu_read_lock_held() || \
task_is_dead(__t)); \
})
/**
* 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_security() (current_cred_xxx(security))
#ifdef CONFIG_USER_NS
#define current_user_ns() (current_cred_xxx(user_ns))
#else
extern struct user_namespace init_user_ns;
#define current_user_ns() (&init_user_ns)
#endif
#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 */
