/* 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;

  		unsigned long		x[2];
  		void			*p[2];

  	} 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, void *aux);

  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 some of the data from a key on revokation (optional)
  	 * - the key's semaphore will be write-locked by the caller
  	 */
  	void (*revoke)(struct key *key);

  	/* 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,
  			     struct task_struct *ctx,

  			     key_perm_t perm,
  			     unsigned long flags);
  
  
  #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 */

  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 struct key *request_key_with_auxdata(struct key_type *type,
  					    const char *description,
  					    const char *callout_info,
  					    void *aux);

  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,

  				      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, uid_t uid, gid_t gid,

  				 struct task_struct *ctx,

  				 unsigned long flags,

  				 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,
  			     struct task_struct *ctx);

  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,c)		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)

  /* Initial keyrings */
  extern struct key root_user_keyring;
  extern struct key root_session_keyring;

  #endif /* CONFIG_KEYS */
  #endif /* __KERNEL__ */
  #endif /* _LINUX_KEY_H */