LXR linux/include/linux/key.h

   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#include <linux/assoc_array.h>
  26
  27#ifdef __KERNEL__
  28#include <linux/uidgid.h>
  29
  30/* key handle serial number */
  31typedef int32_t key_serial_t;
  32
  33/* key handle permissions mask */
  34typedef uint32_t key_perm_t;
  35
  36struct key;
  37
  38#ifdef CONFIG_KEYS
  39
  40#undef KEY_DEBUGGING
  41
  42#define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  43#define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  44#define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  45#define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  46#define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  47#define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  48#define KEY_POS_ALL     0x3f000000
  49
  50#define KEY_USR_VIEW    0x00010000      /* user permissions... */
  51#define KEY_USR_READ    0x00020000
  52#define KEY_USR_WRITE   0x00040000
  53#define KEY_USR_SEARCH  0x00080000
  54#define KEY_USR_LINK    0x00100000
  55#define KEY_USR_SETATTR 0x00200000
  56#define KEY_USR_ALL     0x003f0000
  57
  58#define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  59#define KEY_GRP_READ    0x00000200
  60#define KEY_GRP_WRITE   0x00000400
  61#define KEY_GRP_SEARCH  0x00000800
  62#define KEY_GRP_LINK    0x00001000
  63#define KEY_GRP_SETATTR 0x00002000
  64#define KEY_GRP_ALL     0x00003f00
  65
  66#define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  67#define KEY_OTH_READ    0x00000002
  68#define KEY_OTH_WRITE   0x00000004
  69#define KEY_OTH_SEARCH  0x00000008
  70#define KEY_OTH_LINK    0x00000010
  71#define KEY_OTH_SETATTR 0x00000020
  72#define KEY_OTH_ALL     0x0000003f
  73
  74#define KEY_PERM_UNDEF  0xffffffff
  75
  76struct seq_file;
  77struct user_struct;
  78struct signal_struct;
  79struct cred;
  80
  81struct key_type;
  82struct key_owner;
  83struct keyring_list;
  84struct keyring_name;
  85
  86struct keyring_index_key {
  87        struct key_type         *type;
  88        const char              *description;
  89        size_t                  desc_len;
  90};
  91
  92/*****************************************************************************/
  93/*
  94 * key reference with possession attribute handling
  95 *
  96 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  97 * defined. This is because we abuse the bottom bit of the reference to carry a
  98 * flag to indicate whether the calling process possesses that key in one of
  99 * its keyrings.
 100 *
 101 * the key_ref_t has been made a separate type so that the compiler can reject
 102 * attempts to dereference it without proper conversion.
 103 *
 104 * the three functions are used to assemble and disassemble references
 105 */
 106typedef struct __key_reference_with_attributes *key_ref_t;
 107
 108static inline key_ref_t make_key_ref(const struct key *key,
 109                                     bool possession)
 110{
 111        return (key_ref_t) ((unsigned long) key | possession);
 112}
 113
 114static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 115{
 116        return (struct key *) ((unsigned long) key_ref & ~1UL);
 117}
 118
 119static inline bool is_key_possessed(const key_ref_t key_ref)
 120{
 121        return (unsigned long) key_ref & 1UL;
 122}
 123
 124
 125enum key_state {
 126        KEY_IS_UNINSTANTIATED,
 127        KEY_IS_POSITIVE,                /* Positively instantiated */
 128};
 129
 130/*****************************************************************************/
 131/*
 132 * authentication token / access credential / keyring
 133 * - types of key include:
 134 *   - keyrings
 135 *   - disk encryption IDs
 136 *   - Kerberos TGTs and tickets
 137 */
 138struct key {
 139        atomic_t                usage;          /* number of references */
 140        key_serial_t            serial;         /* key serial number */
 141        union {
 142                struct list_head graveyard_link;
 143                struct rb_node  serial_node;
 144        };
 145        struct rw_semaphore     sem;            /* change vs change sem */
 146        struct key_user         *user;          /* owner of this key */
 147        void                    *security;      /* security data for this key */
 148        union {
 149                time_t          expiry;         /* time at which key expires (or 0) */
 150                time_t          revoked_at;     /* time at which key was revoked */
 151        };
 152        time_t                  last_used_at;   /* last time used for LRU keyring discard */
 153        kuid_t                  uid;
 154        kgid_t                  gid;
 155        key_perm_t              perm;           /* access permissions */
 156        unsigned short          quotalen;       /* length added to quota */
 157        unsigned short          datalen;        /* payload data length
 158                                                 * - may not match RCU dereferenced payload
 159                                                 * - payload should contain own length
 160                                                 */
 161
 162#ifdef KEY_DEBUGGING
 163        unsigned                magic;
 164#define KEY_DEBUG_MAGIC         0x18273645u
 165#endif
 166
 167        unsigned long           flags;          /* status flags (change with bitops) */
 168#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 169#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 170#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 171#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 172#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 173#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 174#define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 175#define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 176#define KEY_FLAG_TRUSTED        8       /* set if key is trusted */
 177#define KEY_FLAG_TRUSTED_ONLY   9       /* set if keyring only accepts links to trusted keys */
 178#define KEY_FLAG_BUILTIN        10      /* set if key is builtin */
 179#define KEY_FLAG_ROOT_CAN_INVAL 11      /* set if key can be invalidated by root without permission */
 180#define KEY_FLAG_UID_KEYRING    12      /* set if key is a user or user session keyring */
 181
 182        /* the key type and key description string
 183         * - the desc is used to match a key against search criteria
 184         * - it should be a printable string
 185         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 186         */
 187        union {
 188                struct keyring_index_key index_key;
 189                struct {
 190                        struct key_type *type;          /* type of key */
 191                        char            *description;
 192                };
 193        };
 194
 195        /* type specific data
 196         * - this is used by the keyring type to index the name
 197         */
 198        union {
 199                struct list_head        link;
 200                unsigned long           x[2];
 201                void                    *p[2];
 202                int                     reject_error;
 203        } type_data;
 204
 205        /* key data
 206         * - this is used to hold the data actually used in cryptography or
 207         *   whatever
 208         */
 209        union {
 210                union {
 211                        unsigned long           value;
 212                        void __rcu              *rcudata;
 213                        void                    *data;
 214                        void                    *data2[2];
 215                } payload;
 216                struct assoc_array keys;
 217        };
 218#ifndef __GENKSYMS__
 219        short state;            /* Key state (+) or rejection error (-) */
 220#endif
 221};
 222
 223extern struct key *key_alloc(struct key_type *type,
 224                             const char *desc,
 225                             kuid_t uid, kgid_t gid,
 226                             const struct cred *cred,
 227                             key_perm_t perm,
 228                             unsigned long flags);
 229
 230
 231#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 232#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 233#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 234#define KEY_ALLOC_TRUSTED       0x0004  /* Key should be flagged as trusted */
 235#define KEY_ALLOC_UID_KEYRING   0x0080  /* allocating a user or user session keyring */
 236
 237extern void key_revoke(struct key *key);
 238extern void key_invalidate(struct key *key);
 239extern void key_put(struct key *key);
 240
 241static inline struct key *__key_get(struct key *key)
 242{
 243        atomic_inc(&key->usage);
 244        return key;
 245}
 246
 247static inline struct key *key_get(struct key *key)
 248{
 249        return key ? __key_get(key) : key;
 250}
 251
 252static inline void key_ref_put(key_ref_t key_ref)
 253{
 254        key_put(key_ref_to_ptr(key_ref));
 255}
 256
 257extern struct key *request_key(struct key_type *type,
 258                               const char *description,
 259                               const char *callout_info);
 260
 261extern struct key *request_key_with_auxdata(struct key_type *type,
 262                                            const char *description,
 263                                            const void *callout_info,
 264                                            size_t callout_len,
 265                                            void *aux);
 266
 267extern struct key *request_key_async(struct key_type *type,
 268                                     const char *description,
 269                                     const void *callout_info,
 270                                     size_t callout_len);
 271
 272extern struct key *request_key_async_with_auxdata(struct key_type *type,
 273                                                  const char *description,
 274                                                  const void *callout_info,
 275                                                  size_t callout_len,
 276                                                  void *aux);
 277
 278extern int wait_for_key_construction(struct key *key, bool intr);
 279
 280extern int key_validate(const struct key *key);
 281
 282extern key_ref_t key_create_or_update(key_ref_t keyring,
 283                                      const char *type,
 284                                      const char *description,
 285                                      const void *payload,
 286                                      size_t plen,
 287                                      key_perm_t perm,
 288                                      unsigned long flags);
 289
 290extern int key_update(key_ref_t key,
 291                      const void *payload,
 292                      size_t plen);
 293
 294extern int key_link(struct key *keyring,
 295                    struct key *key);
 296
 297extern int key_unlink(struct key *keyring,
 298                      struct key *key);
 299
 300extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 301                                 const struct cred *cred,
 302                                 key_perm_t perm,
 303                                 unsigned long flags,
 304                                 struct key *dest);
 305
 306extern int keyring_clear(struct key *keyring);
 307
 308extern key_ref_t keyring_search(key_ref_t keyring,
 309                                struct key_type *type,
 310                                const char *description);
 311
 312extern int keyring_add_key(struct key *keyring,
 313                           struct key *key);
 314
 315extern struct key *key_lookup(key_serial_t id);
 316
 317static inline key_serial_t key_serial(const struct key *key)
 318{
 319        return key ? key->serial : 0;
 320}
 321
 322extern void key_set_timeout(struct key *, unsigned);
 323
 324static inline short key_read_state(const struct key *key)
 325{
 326        /* Barrier versus mark_key_instantiated(). */
 327        return smp_load_acquire(&key->state);
 328}
 329
 330/**
 331 * key_is_positive - Determine if a key has been positively instantiated
 332 * @key: The key to check.
 333 *
 334 * Return true if the specified key has been positively instantiated, false
 335 * otherwise.
 336 */
 337static inline bool key_is_positive(const struct key *key)
 338{
 339        return key_read_state(key) == KEY_IS_POSITIVE;
 340}
 341
 342static inline bool key_is_negative(const struct key *key)
 343{
 344        return key_read_state(key) < 0;
 345}
 346
 347/* rcu_dereference_key() is deprecated. */
 348#define rcu_dereference_key(KEY)                                        \
 349        (rcu_dereference_protected((KEY)->payload.rcudata,              \
 350                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 351
 352#define dereference_key_rcu(KEY)                                        \
 353        (rcu_dereference((KEY)->payload.rcudata))
 354
 355#define dereference_key_locked(KEY)                                     \
 356        (rcu_dereference_protected((KEY)->payload.rcudata,              \
 357                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 358
 359#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 360do {                                                                    \
 361        rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD));          \
 362} while (0)
 363
 364#ifdef CONFIG_SYSCTL
 365extern ctl_table key_sysctls[];
 366#endif
 367/*
 368 * the userspace interface
 369 */
 370extern int install_thread_keyring_to_cred(struct cred *cred);
 371extern void key_fsuid_changed(struct task_struct *tsk);
 372extern void key_fsgid_changed(struct task_struct *tsk);
 373extern void key_init(void);
 374
 375#else /* CONFIG_KEYS */
 376
 377#define key_validate(k)                 0
 378#define key_serial(k)                   0
 379#define key_get(k)                      ({ NULL; })
 380#define key_revoke(k)                   do { } while(0)
 381#define key_invalidate(k)               do { } while(0)
 382#define key_put(k)                      do { } while(0)
 383#define key_ref_put(k)                  do { } while(0)
 384#define make_key_ref(k, p)              NULL
 385#define key_ref_to_ptr(k)               NULL
 386#define is_key_possessed(k)             0
 387#define key_fsuid_changed(t)            do { } while(0)
 388#define key_fsgid_changed(t)            do { } while(0)
 389#define key_init()                      do { } while(0)
 390
 391#endif /* CONFIG_KEYS */
 392#endif /* __KERNEL__ */
 393#endif /* _LINUX_KEY_H */
 394