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kernel-ark/include/linux/key.h
Mat Martineau 6563c91fd6 KEYS: Add KEYCTL_RESTRICT_KEYRING 
Keyrings recently gained restrict_link capabilities that allow
individual keys to be validated prior to linking.  This functionality
was only available using internal kernel APIs.

With the KEYCTL_RESTRICT_KEYRING command existing keyrings can be
configured to check the content of keys before they are linked, and
then allow or disallow linkage of that key to the keyring.

To restrict a keyring, call:

  keyctl(KEYCTL_RESTRICT_KEYRING, key_serial_t keyring, const char *type,
         const char *restriction)

where 'type' is the name of a registered key type and 'restriction' is a
string describing how key linkage is to be restricted. The restriction
option syntax is specific to each key type.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
2017-04-04 14:10:12 -07:00

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/* Authentication token and access key management
*
* Copyright (C) 2004, 2007 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/security/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 <linux/sysctl.h>
#include <linux/rwsem.h>
#include <linux/atomic.h>
#include <linux/assoc_array.h>
#include <linux/refcount.h>
#ifdef __KERNEL__
#include <linux/uidgid.h>
/* 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
#define KEY_PERM_UNDEF 0xffffffff
struct seq_file;
struct user_struct;
struct signal_struct;
struct cred;
struct key_type;
struct key_owner;
struct keyring_list;
struct keyring_name;
struct keyring_index_key {
struct key_type *type;
const char *description;
size_t desc_len;
};
union key_payload {
void __rcu *rcu_data0;
void *data[4];
};
/*****************************************************************************/
/*
* 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,
bool 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 bool is_key_possessed(const key_ref_t key_ref)
{
return (unsigned long) key_ref & 1UL;
}
typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *restriction_key);
struct key_restriction {
key_restrict_link_func_t check;
struct key *key;
struct key_type *keytype;
};
/*****************************************************************************/
/*
* authentication token / access credential / keyring
* - types of key include:
* - keyrings
* - disk encryption IDs
* - Kerberos TGTs and tickets
*/
struct key {
refcount_t usage; /* number of references */
key_serial_t serial; /* key serial number */
union {
struct list_head graveyard_link;
struct rb_node serial_node;
};
struct rw_semaphore sem; /* change vs change sem */
struct key_user *user; /* owner of this key */
void *security; /* security data for this key */
union {
time_t expiry; /* time at which key expires (or 0) */
time_t revoked_at; /* time at which key was revoked */
};
time_t last_used_at; /* last time used for LRU keyring discard */
kuid_t uid;
kgid_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 */
#define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */
#define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */
#define KEY_FLAG_BUILTIN 8 /* set if key is built in to the kernel */
#define KEY_FLAG_ROOT_CAN_INVAL 9 /* set if key can be invalidated by root without permission */
#define KEY_FLAG_KEEP 10 /* set if key should not be removed */
/* the key type and key description string
* - the desc is used to match a key against search criteria
* - it should be a printable string
* - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
*/
union {
struct keyring_index_key index_key;
struct {
struct key_type *type; /* type of key */
char *description;
};
};
/* key data
* - this is used to hold the data actually used in cryptography or
* whatever
*/
union {
union key_payload payload;
struct {
/* Keyring bits */
struct list_head name_link;
struct assoc_array keys;
};
int reject_error;
};
/* This is set on a keyring to restrict the addition of a link to a key
* to it. If this structure isn't provided then it is assumed that the
* keyring is open to any addition. It is ignored for non-keyring
* keys. Only set this value using keyring_restrict(), keyring_alloc(),
* or key_alloc().
*
* This is intended for use with rings of trusted keys whereby addition
* to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
* overrides this, allowing the kernel to add extra keys without
* restriction.
*/
struct key_restriction *restrict_link;
};
extern struct key *key_alloc(struct key_type *type,
const char *desc,
kuid_t uid, kgid_t gid,
const struct cred *cred,
key_perm_t perm,
unsigned long flags,
struct key_restriction *restrict_link);
#define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
#define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
#define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
#define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
extern void key_revoke(struct key *key);
extern void key_invalidate(struct key *key);
extern void key_put(struct key *key);
static inline struct key *__key_get(struct key *key)
{
refcount_inc(&key->usage);
return key;
}
static inline struct key *key_get(struct key *key)
{
return key ? __key_get(key) : 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 struct key *request_key_with_auxdata(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux);
extern struct key *request_key_async(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len);
extern struct key *request_key_async_with_auxdata(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux);
extern int wait_for_key_construction(struct key *key, bool intr);
extern int key_validate(const 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,
key_perm_t perm,
unsigned long flags);
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, kuid_t uid, kgid_t gid,
const struct cred *cred,
key_perm_t perm,
unsigned long flags,
struct key_restriction *restrict_link,
struct key *dest);
extern int restrict_link_reject(struct key *keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *restriction_key);
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 int keyring_restrict(key_ref_t keyring, const char *type,
const char *restriction);
extern struct key *key_lookup(key_serial_t id);
static inline key_serial_t key_serial(const struct key *key)
{
return key ? key->serial : 0;
}
extern void key_set_timeout(struct key *, unsigned);
/*
* The permissions required on a key that we're looking up.
*/
#define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
#define KEY_NEED_READ 0x02 /* Require permission to read content */
#define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
#define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
#define KEY_NEED_LINK 0x10 /* Require permission to link */
#define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
#define KEY_NEED_ALL 0x3f /* All the above permissions */
/**
* key_is_instantiated - Determine if a key has been positively instantiated
* @key: The key to check.
*
* Return true if the specified key has been positively instantiated, false
* otherwise.
*/
static inline bool key_is_instantiated(const struct key *key)
{
return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
!test_bit(KEY_FLAG_NEGATIVE, &key->flags);
}
#define dereference_key_rcu(KEY) \
(rcu_dereference((KEY)->payload.rcu_data0))
#define dereference_key_locked(KEY) \
(rcu_dereference_protected((KEY)->payload.rcu_data0, \
rwsem_is_locked(&((struct key *)(KEY))->sem)))
#define rcu_assign_keypointer(KEY, PAYLOAD) \
do { \
rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
} while (0)
#ifdef CONFIG_SYSCTL
extern struct ctl_table key_sysctls[];
#endif
/*
* the userspace interface
*/
extern int install_thread_keyring_to_cred(struct cred *cred);
extern void key_fsuid_changed(struct task_struct *tsk);
extern void key_fsgid_changed(struct task_struct *tsk);
extern void key_init(void);
#else /* CONFIG_KEYS */
#define key_validate(k) 0
#define key_serial(k) 0
#define key_get(k) ({ NULL; })
#define key_revoke(k) do { } while(0)
#define key_invalidate(k) do { } while(0)
#define key_put(k) do { } while(0)
#define key_ref_put(k) do { } while(0)
#define make_key_ref(k, p) NULL
#define key_ref_to_ptr(k) NULL
#define is_key_possessed(k) 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 */
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