text: /* SPDX-License-Identifier: GPL-2.0-or-later */
  /* Authentication token and access key management
   *
   * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * See Documentation/security/keys/core.rst 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>
  #include <linux/time64.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;
  struct net;
  
  #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
  
  /*
   * The permissions required on a key that we're looking up.
   */
  enum key_need_perm {
  	KEY_NEED_UNSPECIFIED,	/* Needed permission unspecified */
  	KEY_NEED_VIEW,		/* Require permission to view attributes */
  	KEY_NEED_READ,		/* Require permission to read content */
  	KEY_NEED_WRITE,		/* Require permission to update / modify */
  	KEY_NEED_SEARCH,	/* Require permission to search (keyring) or find (key) */
  	KEY_NEED_LINK,		/* Require permission to link */
  	KEY_NEED_SETATTR,	/* Require permission to change attributes */
  	KEY_NEED_UNLINK,	/* Require permission to unlink key */
  	KEY_SYSADMIN_OVERRIDE,	/* Special: override by CAP_SYS_ADMIN */
  	KEY_AUTHTOKEN_OVERRIDE,	/* Special: override by possession of auth token */
  	KEY_DEFER_PERM_CHECK,	/* Special: permission check is deferred */
  };
  
  struct seq_file;
  struct user_struct;
  struct signal_struct;
  struct cred;
  
  struct key_type;
  struct key_owner;
  struct key_tag;
  struct keyring_list;
  struct keyring_name;
  
  struct key_tag {
  	struct rcu_head		rcu;
  	refcount_t		usage;
  	bool			removed;	/* T when subject removed */
  };
  
  struct keyring_index_key {
  	/* [!] If this structure is altered, the union in struct key must change too! */
  	unsigned long		hash;			/* Hash value */
  	union {
  		struct {
  #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
  			u16	desc_len;
  			char	desc[sizeof(long) - 2];	/* First few chars of description */
  #else
  			char	desc[sizeof(long) - 2];	/* First few chars of description */
  			u16	desc_len;
  #endif
  		};
  		unsigned long x;
  	};
  	struct key_type		*type;
  	struct key_tag		*domain_tag;	/* Domain of operation */
  	const char		*description;
  };
  
  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;
  };
  
  enum key_state {
  	KEY_IS_UNINSTANTIATED,
  	KEY_IS_POSITIVE,		/* Positively instantiated */
  };
  
  /*****************************************************************************/
  /*
   * 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;
  	};
  #ifdef CONFIG_KEY_NOTIFICATIONS
  	struct watch_list	*watchers;	/* Entities watching this key for changes */
  #endif
  	struct rw_semaphore	sem;		/* change vs change sem */
  	struct key_user		*user;		/* owner of this key */
  	void			*security;	/* security data for this key */
  	union {
  		time64_t	expiry;		/* time at which key expires (or 0) */
  		time64_t	revoked_at;	/* time at which key was revoked */
  	};
  	time64_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
  						 */
  	short			state;		/* Key state (+) or rejection error (-) */
  
  #ifdef KEY_DEBUGGING
  	unsigned		magic;
  #define KEY_DEBUG_MAGIC		0x18273645u
  #endif
  
  	unsigned long		flags;		/* status flags (change with bitops) */
  #define KEY_FLAG_DEAD		0	/* set if key type has been deleted */
  #define KEY_FLAG_REVOKED	1	/* set if key had been revoked */
  #define KEY_FLAG_IN_QUOTA	2	/* set if key consumes quota */
  #define KEY_FLAG_USER_CONSTRUCT	3	/* set if key is being constructed in userspace */
  #define KEY_FLAG_ROOT_CAN_CLEAR	4	/* set if key can be cleared by root without permission */
  #define KEY_FLAG_INVALIDATED	5	/* set if key has been invalidated */
  #define KEY_FLAG_BUILTIN	6	/* set if key is built in to the kernel */
  #define KEY_FLAG_ROOT_CAN_INVAL	7	/* set if key can be invalidated by root without permission */
  #define KEY_FLAG_KEEP		8	/* set if key should not be removed */
  #define KEY_FLAG_UID_KEYRING	9	/* set if key is a user or user session keyring */
  
  	/* 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 {
  			unsigned long	hash;
  			unsigned long	len_desc;
  			struct key_type	*type;		/* type of key */
  			struct key_tag	*domain_tag;	/* Domain of operation */
  			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;
  		};
  	};
  
  	/* 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 */
  #define KEY_ALLOC_UID_KEYRING		0x0010	/* allocating a user or user session keyring */
  
  extern void key_revoke(struct key *key);
  extern void key_invalidate(struct key *key);
  extern void key_put(struct key *key);
  extern bool key_put_tag(struct key_tag *tag);
  extern void key_remove_domain(struct key_tag *domain_tag);
  
  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_tag(struct key_type *type,
  				   const char *description,
  				   struct key_tag *domain_tag,
  				   const char *callout_info);
  
  extern struct key *request_key_rcu(struct key_type *type,
  				   const char *description,
  				   struct key_tag *domain_tag);
  
  extern struct key *request_key_with_auxdata(struct key_type *type,
  					    const char *description,
  					    struct key_tag *domain_tag,
  					    const void *callout_info,
  					    size_t callout_len,
  					    void *aux);
  
  /**
   * request_key - Request a key and wait for construction
   * @type: Type of key.
   * @description: The searchable description of the key.
   * @callout_info: The data to pass to the instantiation upcall (or NULL).
   *
   * As for request_key_tag(), but with the default global domain tag.
   */
  static inline struct key *request_key(struct key_type *type,
  				      const char *description,
  				      const char *callout_info)
  {
  	return request_key_tag(type, description, NULL, callout_info);
  }
  
  #ifdef CONFIG_NET
  /**
   * request_key_net - Request a key for a net namespace and wait for construction
   * @type: Type of key.
   * @description: The searchable description of the key.
   * @net: The network namespace that is the key's domain of operation.
   * @callout_info: The data to pass to the instantiation upcall (or NULL).
   *
   * As for request_key() except that it does not add the returned key to a
   * keyring if found, new keys are always allocated in the user's quota, the
   * callout_info must be a NUL-terminated string and no auxiliary data can be
   * passed.  Only keys that operate the specified network namespace are used.
   *
   * Furthermore, it then works as wait_for_key_construction() to wait for the
   * completion of keys undergoing construction with a non-interruptible wait.
   */
  #define request_key_net(type, description, net, callout_info) \
  	request_key_tag(type, description, net->key_domain, callout_info);
  
  /**
   * request_key_net_rcu - Request a key for a net namespace under RCU conditions
   * @type: Type of key.
   * @description: The searchable description of the key.
   * @net: The network namespace that is the key's domain of operation.
   *
   * As for request_key_rcu() except that only keys that operate the specified
   * network namespace are used.
   */
  #define request_key_net_rcu(type, description, net) \
  	request_key_rcu(type, description, net->key_domain);
  #endif /* CONFIG_NET */
  
  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_move(struct key *key,
  		    struct key *from_keyring,
  		    struct key *to_keyring,
  		    unsigned int flags);
  
  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,
  				bool recurse);
  
  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);
  
  extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
  				 enum key_need_perm need_perm);
  extern void key_free_user_ns(struct user_namespace *);
  
  static inline short key_read_state(const struct key *key)
  {
  	/* Barrier versus mark_key_instantiated(). */
  	return smp_load_acquire(&key->state);
  }
  
  /**
   * key_is_positive - 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_positive(const struct key *key)
  {
  	return key_read_state(key) == KEY_IS_POSITIVE;
  }
  
  static inline bool key_is_negative(const struct key *key)
  {
  	return key_read_state(key) < 0;
  }
  
  #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 cred *new_cred);
  extern void key_fsgid_changed(struct cred *new_cred);
  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(c)		do { } while(0)
  #define key_fsgid_changed(c)		do { } while(0)
  #define key_init()			do { } while(0)
  #define key_free_user_ns(ns)		do { } while(0)
  #define key_remove_domain(d)		do { } while(0)
  
  #endif /* CONFIG_KEYS */
  #endif /* __KERNEL__ */
  #endif /* _LINUX_KEY_H */
  