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 /* 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 */
 #define KEY_ALLOC_SET_KEEP      0x0020  /* Set the KEEP flag on the key/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 */

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