425 lines
13 KiB
C
425 lines
13 KiB
C
/* Authentication token and access key management
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*
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* Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*
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* See Documentation/security/keys/core.rst for information on keys/keyrings.
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*/
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#ifndef _LINUX_KEY_H
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#define _LINUX_KEY_H
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/rbtree.h>
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#include <linux/rcupdate.h>
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#include <linux/sysctl.h>
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#include <linux/rwsem.h>
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#include <linux/atomic.h>
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#include <linux/assoc_array.h>
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#include <linux/refcount.h>
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#include <linux/time64.h>
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#ifdef __KERNEL__
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#include <linux/uidgid.h>
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/* key handle serial number */
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typedef int32_t key_serial_t;
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/* key handle permissions mask */
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typedef uint32_t key_perm_t;
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struct key;
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#ifdef CONFIG_KEYS
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#undef KEY_DEBUGGING
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#define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
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#define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
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#define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
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#define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
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#define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
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#define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
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#define KEY_POS_ALL 0x3f000000
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#define KEY_USR_VIEW 0x00010000 /* user permissions... */
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#define KEY_USR_READ 0x00020000
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#define KEY_USR_WRITE 0x00040000
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#define KEY_USR_SEARCH 0x00080000
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#define KEY_USR_LINK 0x00100000
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#define KEY_USR_SETATTR 0x00200000
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#define KEY_USR_ALL 0x003f0000
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#define KEY_GRP_VIEW 0x00000100 /* group permissions... */
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#define KEY_GRP_READ 0x00000200
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#define KEY_GRP_WRITE 0x00000400
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#define KEY_GRP_SEARCH 0x00000800
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#define KEY_GRP_LINK 0x00001000
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#define KEY_GRP_SETATTR 0x00002000
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#define KEY_GRP_ALL 0x00003f00
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#define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
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#define KEY_OTH_READ 0x00000002
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#define KEY_OTH_WRITE 0x00000004
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#define KEY_OTH_SEARCH 0x00000008
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#define KEY_OTH_LINK 0x00000010
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#define KEY_OTH_SETATTR 0x00000020
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#define KEY_OTH_ALL 0x0000003f
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#define KEY_PERM_UNDEF 0xffffffff
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struct seq_file;
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struct user_struct;
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struct signal_struct;
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struct cred;
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struct key_type;
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struct key_owner;
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struct keyring_list;
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struct keyring_name;
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struct keyring_index_key {
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struct key_type *type;
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const char *description;
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size_t desc_len;
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};
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union key_payload {
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void __rcu *rcu_data0;
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void *data[4];
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};
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/*****************************************************************************/
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/*
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* key reference with possession attribute handling
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*
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* NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
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* defined. This is because we abuse the bottom bit of the reference to carry a
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* flag to indicate whether the calling process possesses that key in one of
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* its keyrings.
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*
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* the key_ref_t has been made a separate type so that the compiler can reject
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* attempts to dereference it without proper conversion.
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*
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* the three functions are used to assemble and disassemble references
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*/
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typedef struct __key_reference_with_attributes *key_ref_t;
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static inline key_ref_t make_key_ref(const struct key *key,
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bool possession)
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{
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return (key_ref_t) ((unsigned long) key | possession);
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}
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static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
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{
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return (struct key *) ((unsigned long) key_ref & ~1UL);
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}
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static inline bool is_key_possessed(const key_ref_t key_ref)
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{
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return (unsigned long) key_ref & 1UL;
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}
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typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *restriction_key);
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struct key_restriction {
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key_restrict_link_func_t check;
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struct key *key;
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struct key_type *keytype;
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};
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enum key_state {
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KEY_IS_UNINSTANTIATED,
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KEY_IS_POSITIVE, /* Positively instantiated */
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};
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/*****************************************************************************/
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/*
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* authentication token / access credential / keyring
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* - types of key include:
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* - keyrings
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* - disk encryption IDs
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* - Kerberos TGTs and tickets
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*/
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struct key {
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refcount_t usage; /* number of references */
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key_serial_t serial; /* key serial number */
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union {
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struct list_head graveyard_link;
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struct rb_node serial_node;
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};
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struct rw_semaphore sem; /* change vs change sem */
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struct key_user *user; /* owner of this key */
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void *security; /* security data for this key */
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union {
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time64_t expiry; /* time at which key expires (or 0) */
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time64_t revoked_at; /* time at which key was revoked */
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};
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time64_t last_used_at; /* last time used for LRU keyring discard */
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kuid_t uid;
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kgid_t gid;
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key_perm_t perm; /* access permissions */
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unsigned short quotalen; /* length added to quota */
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unsigned short datalen; /* payload data length
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* - may not match RCU dereferenced payload
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* - payload should contain own length
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*/
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short state; /* Key state (+) or rejection error (-) */
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#ifdef KEY_DEBUGGING
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unsigned magic;
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#define KEY_DEBUG_MAGIC 0x18273645u
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#endif
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unsigned long flags; /* status flags (change with bitops) */
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#define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
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#define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
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#define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
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#define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
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#define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
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#define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
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#define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
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#define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
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#define KEY_FLAG_KEEP 8 /* set if key should not be removed */
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#define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
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/* the key type and key description string
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* - the desc is used to match a key against search criteria
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* - it should be a printable string
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* - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
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*/
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union {
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struct keyring_index_key index_key;
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struct {
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struct key_type *type; /* type of key */
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char *description;
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};
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};
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/* key data
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* - this is used to hold the data actually used in cryptography or
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* whatever
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*/
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union {
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union key_payload payload;
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struct {
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/* Keyring bits */
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struct list_head name_link;
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struct assoc_array keys;
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};
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};
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/* This is set on a keyring to restrict the addition of a link to a key
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* to it. If this structure isn't provided then it is assumed that the
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* keyring is open to any addition. It is ignored for non-keyring
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* keys. Only set this value using keyring_restrict(), keyring_alloc(),
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* or key_alloc().
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*
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* This is intended for use with rings of trusted keys whereby addition
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* to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
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* overrides this, allowing the kernel to add extra keys without
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* restriction.
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*/
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struct key_restriction *restrict_link;
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};
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extern struct key *key_alloc(struct key_type *type,
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const char *desc,
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kuid_t uid, kgid_t gid,
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const struct cred *cred,
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key_perm_t perm,
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unsigned long flags,
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struct key_restriction *restrict_link);
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#define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
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#define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
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#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
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#define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
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#define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
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#define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
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extern void key_revoke(struct key *key);
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extern void key_invalidate(struct key *key);
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extern void key_put(struct key *key);
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static inline struct key *__key_get(struct key *key)
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{
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refcount_inc(&key->usage);
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return key;
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}
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static inline struct key *key_get(struct key *key)
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{
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return key ? __key_get(key) : key;
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}
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static inline void key_ref_put(key_ref_t key_ref)
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{
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key_put(key_ref_to_ptr(key_ref));
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}
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extern struct key *request_key(struct key_type *type,
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const char *description,
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const char *callout_info);
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extern struct key *request_key_with_auxdata(struct key_type *type,
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const char *description,
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const void *callout_info,
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size_t callout_len,
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void *aux);
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extern struct key *request_key_async(struct key_type *type,
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const char *description,
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const void *callout_info,
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size_t callout_len);
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extern struct key *request_key_async_with_auxdata(struct key_type *type,
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const char *description,
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const void *callout_info,
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size_t callout_len,
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void *aux);
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extern int wait_for_key_construction(struct key *key, bool intr);
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extern int key_validate(const struct key *key);
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extern key_ref_t key_create_or_update(key_ref_t keyring,
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const char *type,
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const char *description,
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const void *payload,
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size_t plen,
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key_perm_t perm,
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unsigned long flags);
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extern int key_update(key_ref_t key,
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const void *payload,
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size_t plen);
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extern int key_link(struct key *keyring,
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struct key *key);
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extern int key_unlink(struct key *keyring,
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struct key *key);
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extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
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const struct cred *cred,
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key_perm_t perm,
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unsigned long flags,
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struct key_restriction *restrict_link,
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struct key *dest);
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extern int restrict_link_reject(struct key *keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *restriction_key);
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extern int keyring_clear(struct key *keyring);
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extern key_ref_t keyring_search(key_ref_t keyring,
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struct key_type *type,
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const char *description);
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extern int keyring_add_key(struct key *keyring,
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struct key *key);
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extern int keyring_restrict(key_ref_t keyring, const char *type,
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const char *restriction);
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extern struct key *key_lookup(key_serial_t id);
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static inline key_serial_t key_serial(const struct key *key)
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{
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return key ? key->serial : 0;
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}
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extern void key_set_timeout(struct key *, unsigned);
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/*
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* The permissions required on a key that we're looking up.
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*/
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#define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
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#define KEY_NEED_READ 0x02 /* Require permission to read content */
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#define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
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#define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
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#define KEY_NEED_LINK 0x10 /* Require permission to link */
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#define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
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#define KEY_NEED_ALL 0x3f /* All the above permissions */
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static inline short key_read_state(const struct key *key)
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{
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/* Barrier versus mark_key_instantiated(). */
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return smp_load_acquire(&key->state);
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}
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/**
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* key_is_positive - Determine if a key has been positively instantiated
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* @key: The key to check.
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*
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* Return true if the specified key has been positively instantiated, false
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* otherwise.
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*/
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static inline bool key_is_positive(const struct key *key)
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{
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return key_read_state(key) == KEY_IS_POSITIVE;
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}
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static inline bool key_is_negative(const struct key *key)
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{
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return key_read_state(key) < 0;
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}
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#define dereference_key_rcu(KEY) \
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(rcu_dereference((KEY)->payload.rcu_data0))
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#define dereference_key_locked(KEY) \
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(rcu_dereference_protected((KEY)->payload.rcu_data0, \
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rwsem_is_locked(&((struct key *)(KEY))->sem)))
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#define rcu_assign_keypointer(KEY, PAYLOAD) \
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do { \
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rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
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} while (0)
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#ifdef CONFIG_SYSCTL
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extern struct ctl_table key_sysctls[];
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#endif
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/*
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* the userspace interface
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*/
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extern int install_thread_keyring_to_cred(struct cred *cred);
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extern void key_fsuid_changed(struct task_struct *tsk);
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extern void key_fsgid_changed(struct task_struct *tsk);
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extern void key_init(void);
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#else /* CONFIG_KEYS */
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#define key_validate(k) 0
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#define key_serial(k) 0
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#define key_get(k) ({ NULL; })
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#define key_revoke(k) do { } while(0)
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#define key_invalidate(k) do { } while(0)
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#define key_put(k) do { } while(0)
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#define key_ref_put(k) do { } while(0)
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#define make_key_ref(k, p) NULL
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#define key_ref_to_ptr(k) NULL
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#define is_key_possessed(k) 0
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#define key_fsuid_changed(t) do { } while(0)
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#define key_fsgid_changed(t) do { } while(0)
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#define key_init() do { } while(0)
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#endif /* CONFIG_KEYS */
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#endif /* __KERNEL__ */
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#endif /* _LINUX_KEY_H */
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