linux/include/linux/key.h
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   1/* Authentication token and access key management
   2 *
   3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 *
  11 *
  12 * See Documentation/security/keys.txt for information on keys/keyrings.
  13 */
  14
  15#ifndef _LINUX_KEY_H
  16#define _LINUX_KEY_H
  17
  18#include <linux/types.h>
  19#include <linux/list.h>
  20#include <linux/rbtree.h>
  21#include <linux/rcupdate.h>
  22#include <linux/sysctl.h>
  23#include <linux/rwsem.h>
  24#include <linux/atomic.h>
  25
  26#ifdef __KERNEL__
  27
  28/* key handle serial number */
  29typedef int32_t key_serial_t;
  30
  31/* key handle permissions mask */
  32typedef uint32_t key_perm_t;
  33
  34struct key;
  35
  36#ifdef CONFIG_KEYS
  37
  38#undef KEY_DEBUGGING
  39
  40#define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  41#define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  42#define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  43#define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  44#define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  45#define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  46#define KEY_POS_ALL     0x3f000000
  47
  48#define KEY_USR_VIEW    0x00010000      /* user permissions... */
  49#define KEY_USR_READ    0x00020000
  50#define KEY_USR_WRITE   0x00040000
  51#define KEY_USR_SEARCH  0x00080000
  52#define KEY_USR_LINK    0x00100000
  53#define KEY_USR_SETATTR 0x00200000
  54#define KEY_USR_ALL     0x003f0000
  55
  56#define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  57#define KEY_GRP_READ    0x00000200
  58#define KEY_GRP_WRITE   0x00000400
  59#define KEY_GRP_SEARCH  0x00000800
  60#define KEY_GRP_LINK    0x00001000
  61#define KEY_GRP_SETATTR 0x00002000
  62#define KEY_GRP_ALL     0x00003f00
  63
  64#define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  65#define KEY_OTH_READ    0x00000002
  66#define KEY_OTH_WRITE   0x00000004
  67#define KEY_OTH_SEARCH  0x00000008
  68#define KEY_OTH_LINK    0x00000010
  69#define KEY_OTH_SETATTR 0x00000020
  70#define KEY_OTH_ALL     0x0000003f
  71
  72#define KEY_PERM_UNDEF  0xffffffff
  73
  74struct seq_file;
  75struct user_struct;
  76struct signal_struct;
  77struct cred;
  78
  79struct key_type;
  80struct key_owner;
  81struct keyring_list;
  82struct keyring_name;
  83
  84/*****************************************************************************/
  85/*
  86 * key reference with possession attribute handling
  87 *
  88 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  89 * defined. This is because we abuse the bottom bit of the reference to carry a
  90 * flag to indicate whether the calling process possesses that key in one of
  91 * its keyrings.
  92 *
  93 * the key_ref_t has been made a separate type so that the compiler can reject
  94 * attempts to dereference it without proper conversion.
  95 *
  96 * the three functions are used to assemble and disassemble references
  97 */
  98typedef struct __key_reference_with_attributes *key_ref_t;
  99
 100static inline key_ref_t make_key_ref(const struct key *key,
 101                                     unsigned long possession)
 102{
 103        return (key_ref_t) ((unsigned long) key | possession);
 104}
 105
 106static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 107{
 108        return (struct key *) ((unsigned long) key_ref & ~1UL);
 109}
 110
 111static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 112{
 113        return (unsigned long) key_ref & 1UL;
 114}
 115
 116/*****************************************************************************/
 117/*
 118 * authentication token / access credential / keyring
 119 * - types of key include:
 120 *   - keyrings
 121 *   - disk encryption IDs
 122 *   - Kerberos TGTs and tickets
 123 */
 124struct key {
 125        atomic_t                usage;          /* number of references */
 126        key_serial_t            serial;         /* key serial number */
 127        union {
 128                struct list_head graveyard_link;
 129                struct rb_node  serial_node;
 130        };
 131        struct key_type         *type;          /* type of key */
 132        struct rw_semaphore     sem;            /* change vs change sem */
 133        struct key_user         *user;          /* owner of this key */
 134        void                    *security;      /* security data for this key */
 135        union {
 136                time_t          expiry;         /* time at which key expires (or 0) */
 137                time_t          revoked_at;     /* time at which key was revoked */
 138        };
 139        time_t                  last_used_at;   /* last time used for LRU keyring discard */
 140        uid_t                   uid;
 141        gid_t                   gid;
 142        key_perm_t              perm;           /* access permissions */
 143        unsigned short          quotalen;       /* length added to quota */
 144        unsigned short          datalen;        /* payload data length
 145                                                 * - may not match RCU dereferenced payload
 146                                                 * - payload should contain own length
 147                                                 */
 148
 149#ifdef KEY_DEBUGGING
 150        unsigned                magic;
 151#define KEY_DEBUG_MAGIC         0x18273645u
 152#define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 153#endif
 154
 155        unsigned long           flags;          /* status flags (change with bitops) */
 156#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 157#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 158#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 159#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 160#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 161#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 162#define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 163#define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 164
 165        /* the description string
 166         * - this is used to match a key against search criteria
 167         * - this should be a printable string
 168         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 169         */
 170        char                    *description;
 171
 172        /* type specific data
 173         * - this is used by the keyring type to index the name
 174         */
 175        union {
 176                struct list_head        link;
 177                unsigned long           x[2];
 178                void                    *p[2];
 179                int                     reject_error;
 180        } type_data;
 181
 182        /* key data
 183         * - this is used to hold the data actually used in cryptography or
 184         *   whatever
 185         */
 186        union {
 187                unsigned long           value;
 188                void __rcu              *rcudata;
 189                void                    *data;
 190                struct keyring_list __rcu *subscriptions;
 191        } payload;
 192};
 193
 194extern struct key *key_alloc(struct key_type *type,
 195                             const char *desc,
 196                             uid_t uid, gid_t gid,
 197                             const struct cred *cred,
 198                             key_perm_t perm,
 199                             unsigned long flags);
 200
 201
 202#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 203#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 204#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 205
 206extern void key_revoke(struct key *key);
 207extern void key_invalidate(struct key *key);
 208extern void key_put(struct key *key);
 209
 210static inline struct key *key_get(struct key *key)
 211{
 212        if (key)
 213                atomic_inc(&key->usage);
 214        return key;
 215}
 216
 217static inline void key_ref_put(key_ref_t key_ref)
 218{
 219        key_put(key_ref_to_ptr(key_ref));
 220}
 221
 222extern struct key *request_key(struct key_type *type,
 223                               const char *description,
 224                               const char *callout_info);
 225
 226extern struct key *request_key_with_auxdata(struct key_type *type,
 227                                            const char *description,
 228                                            const void *callout_info,
 229                                            size_t callout_len,
 230                                            void *aux);
 231
 232extern struct key *request_key_async(struct key_type *type,
 233                                     const char *description,
 234                                     const void *callout_info,
 235                                     size_t callout_len);
 236
 237extern struct key *request_key_async_with_auxdata(struct key_type *type,
 238                                                  const char *description,
 239                                                  const void *callout_info,
 240                                                  size_t callout_len,
 241                                                  void *aux);
 242
 243extern int wait_for_key_construction(struct key *key, bool intr);
 244
 245extern int key_validate(const struct key *key);
 246
 247extern key_ref_t key_create_or_update(key_ref_t keyring,
 248                                      const char *type,
 249                                      const char *description,
 250                                      const void *payload,
 251                                      size_t plen,
 252                                      key_perm_t perm,
 253                                      unsigned long flags);
 254
 255extern int key_update(key_ref_t key,
 256                      const void *payload,
 257                      size_t plen);
 258
 259extern int key_link(struct key *keyring,
 260                    struct key *key);
 261
 262extern int key_unlink(struct key *keyring,
 263                      struct key *key);
 264
 265extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 266                                 const struct cred *cred,
 267                                 unsigned long flags,
 268                                 struct key *dest);
 269
 270extern int keyring_clear(struct key *keyring);
 271
 272extern key_ref_t keyring_search(key_ref_t keyring,
 273                                struct key_type *type,
 274                                const char *description);
 275
 276extern int keyring_add_key(struct key *keyring,
 277                           struct key *key);
 278
 279extern struct key *key_lookup(key_serial_t id);
 280
 281static inline key_serial_t key_serial(const struct key *key)
 282{
 283        return key ? key->serial : 0;
 284}
 285
 286extern void key_set_timeout(struct key *, unsigned);
 287
 288/**
 289 * key_is_instantiated - Determine if a key has been positively instantiated
 290 * @key: The key to check.
 291 *
 292 * Return true if the specified key has been positively instantiated, false
 293 * otherwise.
 294 */
 295static inline bool key_is_instantiated(const struct key *key)
 296{
 297        return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 298                !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 299}
 300
 301#define rcu_dereference_key(KEY)                                        \
 302        (rcu_dereference_protected((KEY)->payload.rcudata,              \
 303                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 304
 305#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 306do {                                                                    \
 307        rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD));          \
 308} while (0)
 309
 310#ifdef CONFIG_SYSCTL
 311extern ctl_table key_sysctls[];
 312#endif
 313/*
 314 * the userspace interface
 315 */
 316extern int install_thread_keyring_to_cred(struct cred *cred);
 317extern void key_fsuid_changed(struct task_struct *tsk);
 318extern void key_fsgid_changed(struct task_struct *tsk);
 319extern void key_init(void);
 320
 321#else /* CONFIG_KEYS */
 322
 323#define key_validate(k)                 0
 324#define key_serial(k)                   0
 325#define key_get(k)                      ({ NULL; })
 326#define key_revoke(k)                   do { } while(0)
 327#define key_invalidate(k)               do { } while(0)
 328#define key_put(k)                      do { } while(0)
 329#define key_ref_put(k)                  do { } while(0)
 330#define make_key_ref(k, p)              NULL
 331#define key_ref_to_ptr(k)               NULL
 332#define is_key_possessed(k)             0
 333#define key_fsuid_changed(t)            do { } while(0)
 334#define key_fsgid_changed(t)            do { } while(0)
 335#define key_init()                      do { } while(0)
 336
 337#endif /* CONFIG_KEYS */
 338#endif /* __KERNEL__ */
 339#endif /* _LINUX_KEY_H */
 340
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