kernel-ark/include/linux/key.h
David Howells b5f545c880 [PATCH] keys: Permit running process to instantiate keys
Make it possible for a running process (such as gssapid) to be able to
instantiate a key, as was requested by Trond Myklebust for NFS4.

The patch makes the following changes:

 (1) A new, optional key type method has been added. This permits a key type
     to intercept requests at the point /sbin/request-key is about to be
     spawned and do something else with them - passing them over the
     rpc_pipefs files or netlink sockets for instance.

     The uninstantiated key, the authorisation key and the intended operation
     name are passed to the method.

 (2) The callout_info is no longer passed as an argument to /sbin/request-key
     to prevent unauthorised viewing of this data using ps or by looking in
     /proc/pid/cmdline.

     This means that the old /sbin/request-key program will not work with the
     patched kernel as it will expect to see an extra argument that is no
     longer there.

     A revised keyutils package will be made available tomorrow.

 (3) The callout_info is now attached to the authorisation key. Reading this
     key will retrieve the information.

 (4) A new field has been added to the task_struct. This holds the
     authorisation key currently active for a thread. Searches now look here
     for the caller's set of keys rather than looking for an auth key in the
     lowest level of the session keyring.

     This permits a thread to be servicing multiple requests at once and to
     switch between them. Note that this is per-thread, not per-process, and
     so is usable in multithreaded programs.

     The setting of this field is inherited across fork and exec.

 (5) A new keyctl function (KEYCTL_ASSUME_AUTHORITY) has been added that
     permits a thread to assume the authority to deal with an uninstantiated
     key. Assumption is only permitted if the authorisation key associated
     with the uninstantiated key is somewhere in the thread's keyrings.

     This function can also clear the assumption.

 (6) A new magic key specifier has been added to refer to the currently
     assumed authorisation key (KEY_SPEC_REQKEY_AUTH_KEY).

 (7) Instantiation will only proceed if the appropriate authorisation key is
     assumed first. The assumed authorisation key is discarded if
     instantiation is successful.

 (8) key_validate() is moved from the file of request_key functions to the
     file of permissions functions.

 (9) The documentation is updated.

From: <Valdis.Kletnieks@vt.edu>

    Build fix.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Alexander Zangerl <az@bond.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 20:13:53 -08:00

361 lines
11 KiB
C

/* key.h: authentication token and access key management
*
* Copyright (C) 2004 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 License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*
* See Documentation/keys.txt for information on keys/keyrings.
*/
#ifndef _LINUX_KEY_H
#define _LINUX_KEY_H
#include <linux/types.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.h>
#include <asm/atomic.h>
#ifdef __KERNEL__
/* key handle serial number */
typedef int32_t key_serial_t;
/* key handle permissions mask */
typedef uint32_t key_perm_t;
struct key;
#ifdef CONFIG_KEYS
#undef KEY_DEBUGGING
#define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
#define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
#define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
#define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
#define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
#define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
#define KEY_POS_ALL 0x3f000000
#define KEY_USR_VIEW 0x00010000 /* user permissions... */
#define KEY_USR_READ 0x00020000
#define KEY_USR_WRITE 0x00040000
#define KEY_USR_SEARCH 0x00080000
#define KEY_USR_LINK 0x00100000
#define KEY_USR_SETATTR 0x00200000
#define KEY_USR_ALL 0x003f0000
#define KEY_GRP_VIEW 0x00000100 /* group permissions... */
#define KEY_GRP_READ 0x00000200
#define KEY_GRP_WRITE 0x00000400
#define KEY_GRP_SEARCH 0x00000800
#define KEY_GRP_LINK 0x00001000
#define KEY_GRP_SETATTR 0x00002000
#define KEY_GRP_ALL 0x00003f00
#define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
#define KEY_OTH_READ 0x00000002
#define KEY_OTH_WRITE 0x00000004
#define KEY_OTH_SEARCH 0x00000008
#define KEY_OTH_LINK 0x00000010
#define KEY_OTH_SETATTR 0x00000020
#define KEY_OTH_ALL 0x0000003f
struct seq_file;
struct user_struct;
struct signal_struct;
struct key_type;
struct key_owner;
struct keyring_list;
struct keyring_name;
/*****************************************************************************/
/*
* key reference with possession attribute handling
*
* NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
* defined. This is because we abuse the bottom bit of the reference to carry a
* flag to indicate whether the calling process possesses that key in one of
* its keyrings.
*
* the key_ref_t has been made a separate type so that the compiler can reject
* attempts to dereference it without proper conversion.
*
* the three functions are used to assemble and disassemble references
*/
typedef struct __key_reference_with_attributes *key_ref_t;
static inline key_ref_t make_key_ref(const struct key *key,
unsigned long possession)
{
return (key_ref_t) ((unsigned long) key | possession);
}
static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
{
return (struct key *) ((unsigned long) key_ref & ~1UL);
}
static inline unsigned long is_key_possessed(const key_ref_t key_ref)
{
return (unsigned long) key_ref & 1UL;
}
/*****************************************************************************/
/*
* authentication token / access credential / keyring
* - types of key include:
* - keyrings
* - disk encryption IDs
* - Kerberos TGTs and tickets
*/
struct key {
atomic_t usage; /* number of references */
key_serial_t serial; /* key serial number */
struct rb_node serial_node;
struct key_type *type; /* type of key */
struct rw_semaphore sem; /* change vs change sem */
struct key_user *user; /* owner of this key */
void *security; /* security data for this key */
time_t expiry; /* time at which key expires (or 0) */
uid_t uid;
gid_t gid;
key_perm_t perm; /* access permissions */
unsigned short quotalen; /* length added to quota */
unsigned short datalen; /* payload data length
* - may not match RCU dereferenced payload
* - payload should contain own length
*/
#ifdef KEY_DEBUGGING
unsigned magic;
#define KEY_DEBUG_MAGIC 0x18273645u
#define KEY_DEBUG_MAGIC_X 0xf8e9dacbu
#endif
unsigned long flags; /* status flags (change with bitops) */
#define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */
#define KEY_FLAG_DEAD 1 /* set if key type has been deleted */
#define KEY_FLAG_REVOKED 2 /* set if key had been revoked */
#define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */
#define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */
#define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
/* the description string
* - this is used to match a key against search criteria
* - this should be a printable string
* - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
*/
char *description;
/* type specific data
* - this is used by the keyring type to index the name
*/
union {
struct list_head link;
} type_data;
/* key data
* - this is used to hold the data actually used in cryptography or
* whatever
*/
union {
unsigned long value;
void *data;
struct keyring_list *subscriptions;
} payload;
};
/*****************************************************************************/
/*
* kernel managed key type definition
*/
typedef int (*request_key_actor_t)(struct key *key, struct key *authkey, const char *op);
struct key_type {
/* name of the type */
const char *name;
/* default payload length for quota precalculation (optional)
* - this can be used instead of calling key_payload_reserve(), that
* function only needs to be called if the real datalen is different
*/
size_t def_datalen;
/* instantiate a key of this type
* - this method should call key_payload_reserve() to determine if the
* user's quota will hold the payload
*/
int (*instantiate)(struct key *key, const void *data, size_t datalen);
/* update a key of this type (optional)
* - this method should call key_payload_reserve() to recalculate the
* quota consumption
* - the key must be locked against read when modifying
*/
int (*update)(struct key *key, const void *data, size_t datalen);
/* match a key against a description */
int (*match)(const struct key *key, const void *desc);
/* clear the data from a key (optional) */
void (*destroy)(struct key *key);
/* describe a key */
void (*describe)(const struct key *key, struct seq_file *p);
/* read a key's data (optional)
* - permission checks will be done by the caller
* - the key's semaphore will be readlocked by the caller
* - should return the amount of data that could be read, no matter how
* much is copied into the buffer
* - shouldn't do the copy if the buffer is NULL
*/
long (*read)(const struct key *key, char __user *buffer, size_t buflen);
/* handle request_key() for this type instead of invoking
* /sbin/request-key (optional)
* - key is the key to instantiate
* - authkey is the authority to assume when instantiating this key
* - op is the operation to be done, usually "create"
* - the call must not return until the instantiation process has run
* its course
*/
request_key_actor_t request_key;
/* internal fields */
struct list_head link; /* link in types list */
};
extern struct key_type key_type_keyring;
extern int register_key_type(struct key_type *ktype);
extern void unregister_key_type(struct key_type *ktype);
extern struct key *key_alloc(struct key_type *type,
const char *desc,
uid_t uid, gid_t gid, key_perm_t perm,
int not_in_quota);
extern int key_payload_reserve(struct key *key, size_t datalen);
extern int key_instantiate_and_link(struct key *key,
const void *data,
size_t datalen,
struct key *keyring,
struct key *instkey);
extern int key_negate_and_link(struct key *key,
unsigned timeout,
struct key *keyring,
struct key *instkey);
extern void key_revoke(struct key *key);
extern void key_put(struct key *key);
static inline struct key *key_get(struct key *key)
{
if (key)
atomic_inc(&key->usage);
return key;
}
static inline void key_ref_put(key_ref_t key_ref)
{
key_put(key_ref_to_ptr(key_ref));
}
extern struct key *request_key(struct key_type *type,
const char *description,
const char *callout_info);
extern int key_validate(struct key *key);
extern key_ref_t key_create_or_update(key_ref_t keyring,
const char *type,
const char *description,
const void *payload,
size_t plen,
int not_in_quota);
extern int key_update(key_ref_t key,
const void *payload,
size_t plen);
extern int key_link(struct key *keyring,
struct key *key);
extern int key_unlink(struct key *keyring,
struct key *key);
extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
int not_in_quota, struct key *dest);
extern int keyring_clear(struct key *keyring);
extern key_ref_t keyring_search(key_ref_t keyring,
struct key_type *type,
const char *description);
extern int keyring_add_key(struct key *keyring,
struct key *key);
extern struct key *key_lookup(key_serial_t id);
extern void keyring_replace_payload(struct key *key, void *replacement);
#define key_serial(key) ((key) ? (key)->serial : 0)
/*
* the userspace interface
*/
extern struct key root_user_keyring, root_session_keyring;
extern int alloc_uid_keyring(struct user_struct *user);
extern void switch_uid_keyring(struct user_struct *new_user);
extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
extern int copy_thread_group_keys(struct task_struct *tsk);
extern void exit_keys(struct task_struct *tsk);
extern void exit_thread_group_keys(struct signal_struct *tg);
extern int suid_keys(struct task_struct *tsk);
extern int exec_keys(struct task_struct *tsk);
extern void key_fsuid_changed(struct task_struct *tsk);
extern void key_fsgid_changed(struct task_struct *tsk);
extern void key_init(void);
#define __install_session_keyring(tsk, keyring) \
({ \
struct key *old_session = tsk->signal->session_keyring; \
tsk->signal->session_keyring = keyring; \
old_session; \
})
#else /* CONFIG_KEYS */
#define key_validate(k) 0
#define key_serial(k) 0
#define key_get(k) ({ NULL; })
#define key_put(k) do { } while(0)
#define key_ref_put(k) do { } while(0)
#define make_key_ref(k) ({ NULL; })
#define key_ref_to_ptr(k) ({ NULL; })
#define is_key_possessed(k) 0
#define alloc_uid_keyring(u) 0
#define switch_uid_keyring(u) do { } while(0)
#define __install_session_keyring(t, k) ({ NULL; })
#define copy_keys(f,t) 0
#define copy_thread_group_keys(t) 0
#define exit_keys(t) do { } while(0)
#define exit_thread_group_keys(tg) do { } while(0)
#define suid_keys(t) do { } while(0)
#define exec_keys(t) do { } while(0)
#define key_fsuid_changed(t) do { } while(0)
#define key_fsgid_changed(t) do { } while(0)
#define key_init() do { } while(0)
#endif /* CONFIG_KEYS */
#endif /* __KERNEL__ */
#endif /* _LINUX_KEY_H */