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#include <linux/refcount.h>
  27
  28#ifdef __KERNEL__
  29#include <linux/uidgid.h>
  30
  31/* key handle serial number */
  32typedef int32_t key_serial_t;
  33
  34/* key handle permissions mask */
  35typedef uint32_t key_perm_t;
  36
  37struct key;
  38
  39#ifdef CONFIG_KEYS
  40
  41#undef KEY_DEBUGGING
  42
  43#define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  44#define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  45#define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  46#define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  47#define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  48#define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  49#define KEY_POS_ALL     0x3f000000
  50
  51#define KEY_USR_VIEW    0x00010000      /* user permissions... */
  52#define KEY_USR_READ    0x00020000
  53#define KEY_USR_WRITE   0x00040000
  54#define KEY_USR_SEARCH  0x00080000
  55#define KEY_USR_LINK    0x00100000
  56#define KEY_USR_SETATTR 0x00200000
  57#define KEY_USR_ALL     0x003f0000
  58
  59#define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  60#define KEY_GRP_READ    0x00000200
  61#define KEY_GRP_WRITE   0x00000400
  62#define KEY_GRP_SEARCH  0x00000800
  63#define KEY_GRP_LINK    0x00001000
  64#define KEY_GRP_SETATTR 0x00002000
  65#define KEY_GRP_ALL     0x00003f00
  66
  67#define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  68#define KEY_OTH_READ    0x00000002
  69#define KEY_OTH_WRITE   0x00000004
  70#define KEY_OTH_SEARCH  0x00000008
  71#define KEY_OTH_LINK    0x00000010
  72#define KEY_OTH_SETATTR 0x00000020
  73#define KEY_OTH_ALL     0x0000003f
  74
  75#define KEY_PERM_UNDEF  0xffffffff
  76
  77struct seq_file;
  78struct user_struct;
  79struct signal_struct;
  80struct cred;
  81
  82struct key_type;
  83struct key_owner;
  84struct keyring_list;
  85struct keyring_name;
  86
  87struct keyring_index_key {
  88        struct key_type         *type;
  89        const char              *description;
  90        size_t                  desc_len;
  91};
  92
  93union key_payload {
  94        void __rcu              *rcu_data0;
  95        void                    *data[4];
  96};
  97
  98/*****************************************************************************/
  99/*
 100 * key reference with possession attribute handling
 101 *
 102 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 103 * defined. This is because we abuse the bottom bit of the reference to carry a
 104 * flag to indicate whether the calling process possesses that key in one of
 105 * its keyrings.
 106 *
 107 * the key_ref_t has been made a separate type so that the compiler can reject
 108 * attempts to dereference it without proper conversion.
 109 *
 110 * the three functions are used to assemble and disassemble references
 111 */
 112typedef struct __key_reference_with_attributes *key_ref_t;
 113
 114static inline key_ref_t make_key_ref(const struct key *key,
 115                                     bool possession)
 116{
 117        return (key_ref_t) ((unsigned long) key | possession);
 118}
 119
 120static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 121{
 122        return (struct key *) ((unsigned long) key_ref & ~1UL);
 123}
 124
 125static inline bool is_key_possessed(const key_ref_t key_ref)
 126{
 127        return (unsigned long) key_ref & 1UL;
 128}
 129
 130typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
 131                                        const struct key_type *type,
 132                                        const union key_payload *payload,
 133                                        struct key *restriction_key);
 134
 135struct key_restriction {
 136        key_restrict_link_func_t check;
 137        struct key *key;
 138        struct key_type *keytype;
 139};
 140
 141/*****************************************************************************/
 142/*
 143 * authentication token / access credential / keyring
 144 * - types of key include:
 145 *   - keyrings
 146 *   - disk encryption IDs
 147 *   - Kerberos TGTs and tickets
 148 */
 149struct key {
 150        refcount_t              usage;          /* number of references */
 151        key_serial_t            serial;         /* key serial number */
 152        union {
 153                struct list_head graveyard_link;
 154                struct rb_node  serial_node;
 155        };
 156        struct rw_semaphore     sem;            /* change vs change sem */
 157        struct key_user         *user;          /* owner of this key */
 158        void                    *security;      /* security data for this key */
 159        union {
 160                time_t          expiry;         /* time at which key expires (or 0) */
 161                time_t          revoked_at;     /* time at which key was revoked */
 162        };
 163        time_t                  last_used_at;   /* last time used for LRU keyring discard */
 164        kuid_t                  uid;
 165        kgid_t                  gid;
 166        key_perm_t              perm;           /* access permissions */
 167        unsigned short          quotalen;       /* length added to quota */
 168        unsigned short          datalen;        /* payload data length
 169                                                 * - may not match RCU dereferenced payload
 170                                                 * - payload should contain own length
 171                                                 */
 172
 173#ifdef KEY_DEBUGGING
 174        unsigned                magic;
 175#define KEY_DEBUG_MAGIC         0x18273645u
 176#endif
 177
 178        unsigned long           flags;          /* status flags (change with bitops) */
 179#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 180#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 181#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 182#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 183#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 184#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 185#define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 186#define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 187#define KEY_FLAG_BUILTIN        8       /* set if key is built in to the kernel */
 188#define KEY_FLAG_ROOT_CAN_INVAL 9       /* set if key can be invalidated by root without permission */
 189#define KEY_FLAG_KEEP           10      /* set if key should not be removed */
 190
 191        /* the key type and key description string
 192         * - the desc is used to match a key against search criteria
 193         * - it should be a printable string
 194         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 195         */
 196        union {
 197                struct keyring_index_key index_key;
 198                struct {
 199                        struct key_type *type;          /* type of key */
 200                        char            *description;
 201                };
 202        };
 203
 204        /* key data
 205         * - this is used to hold the data actually used in cryptography or
 206         *   whatever
 207         */
 208        union {
 209                union key_payload payload;
 210                struct {
 211                        /* Keyring bits */
 212                        struct list_head name_link;
 213                        struct assoc_array keys;
 214                };
 215                int reject_error;
 216        };
 217
 218        /* This is set on a keyring to restrict the addition of a link to a key
 219         * to it.  If this structure isn't provided then it is assumed that the
 220         * keyring is open to any addition.  It is ignored for non-keyring
 221         * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 222         * or key_alloc().
 223         *
 224         * This is intended for use with rings of trusted keys whereby addition
 225         * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 226         * overrides this, allowing the kernel to add extra keys without
 227         * restriction.
 228         */
 229        struct key_restriction *restrict_link;
 230};
 231
 232extern struct key *key_alloc(struct key_type *type,
 233                             const char *desc,
 234                             kuid_t uid, kgid_t gid,
 235                             const struct cred *cred,
 236                             key_perm_t perm,
 237                             unsigned long flags,
 238                             struct key_restriction *restrict_link);
 239
 240
 241#define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 242#define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 243#define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 244#define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 245#define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 246
 247extern void key_revoke(struct key *key);
 248extern void key_invalidate(struct key *key);
 249extern void key_put(struct key *key);
 250
 251static inline struct key *__key_get(struct key *key)
 252{
 253        refcount_inc(&key->usage);
 254        return key;
 255}
 256
 257static inline struct key *key_get(struct key *key)
 258{
 259        return key ? __key_get(key) : key;
 260}
 261
 262static inline void key_ref_put(key_ref_t key_ref)
 263{
 264        key_put(key_ref_to_ptr(key_ref));
 265}
 266
 267extern struct key *request_key(struct key_type *type,
 268                               const char *description,
 269                               const char *callout_info);
 270
 271extern struct key *request_key_with_auxdata(struct key_type *type,
 272                                            const char *description,
 273                                            const void *callout_info,
 274                                            size_t callout_len,
 275                                            void *aux);
 276
 277extern struct key *request_key_async(struct key_type *type,
 278                                     const char *description,
 279                                     const void *callout_info,
 280                                     size_t callout_len);
 281
 282extern struct key *request_key_async_with_auxdata(struct key_type *type,
 283                                                  const char *description,
 284                                                  const void *callout_info,
 285                                                  size_t callout_len,
 286                                                  void *aux);
 287
 288extern int wait_for_key_construction(struct key *key, bool intr);
 289
 290extern int key_validate(const struct key *key);
 291
 292extern key_ref_t key_create_or_update(key_ref_t keyring,
 293                                      const char *type,
 294                                      const char *description,
 295                                      const void *payload,
 296                                      size_t plen,
 297                                      key_perm_t perm,
 298                                      unsigned long flags);
 299
 300extern int key_update(key_ref_t key,
 301                      const void *payload,
 302                      size_t plen);
 303
 304extern int key_link(struct key *keyring,
 305                    struct key *key);
 306
 307extern int key_unlink(struct key *keyring,
 308                      struct key *key);
 309
 310extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 311                                 const struct cred *cred,
 312                                 key_perm_t perm,
 313                                 unsigned long flags,
 314                                 struct key_restriction *restrict_link,
 315                                 struct key *dest);
 316
 317extern int restrict_link_reject(struct key *keyring,
 318                                const struct key_type *type,
 319                                const union key_payload *payload,
 320                                struct key *restriction_key);
 321
 322extern int keyring_clear(struct key *keyring);
 323
 324extern key_ref_t keyring_search(key_ref_t keyring,
 325                                struct key_type *type,
 326                                const char *description);
 327
 328extern int keyring_add_key(struct key *keyring,
 329                           struct key *key);
 330
 331extern int keyring_restrict(key_ref_t keyring, const char *type,
 332                            const char *restriction);
 333
 334extern struct key *key_lookup(key_serial_t id);
 335
 336static inline key_serial_t key_serial(const struct key *key)
 337{
 338        return key ? key->serial : 0;
 339}
 340
 341extern void key_set_timeout(struct key *, unsigned);
 342
 343/*
 344 * The permissions required on a key that we're looking up.
 345 */
 346#define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 347#define KEY_NEED_READ   0x02    /* Require permission to read content */
 348#define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 349#define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 350#define KEY_NEED_LINK   0x10    /* Require permission to link */
 351#define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 352#define KEY_NEED_ALL    0x3f    /* All the above permissions */
 353
 354/**
 355 * key_is_instantiated - Determine if a key has been positively instantiated
 356 * @key: The key to check.
 357 *
 358 * Return true if the specified key has been positively instantiated, false
 359 * otherwise.
 360 */
 361static inline bool key_is_instantiated(const struct key *key)
 362{
 363        return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 364                !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 365}
 366
 367#define dereference_key_rcu(KEY)                                        \
 368        (rcu_dereference((KEY)->payload.rcu_data0))
 369
 370#define dereference_key_locked(KEY)                                     \
 371        (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 372                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 373
 374#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 375do {                                                                    \
 376        rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 377} while (0)
 378
 379#ifdef CONFIG_SYSCTL
 380extern struct ctl_table key_sysctls[];
 381#endif
 382/*
 383 * the userspace interface
 384 */
 385extern int install_thread_keyring_to_cred(struct cred *cred);
 386extern void key_fsuid_changed(struct task_struct *tsk);
 387extern void key_fsgid_changed(struct task_struct *tsk);
 388extern void key_init(void);
 389
 390#else /* CONFIG_KEYS */
 391
 392#define key_validate(k)                 0
 393#define key_serial(k)                   0
 394#define key_get(k)                      ({ NULL; })
 395#define key_revoke(k)                   do { } while(0)
 396#define key_invalidate(k)               do { } while(0)
 397#define key_put(k)                      do { } while(0)
 398#define key_ref_put(k)                  do { } while(0)
 399#define make_key_ref(k, p)              NULL
 400#define key_ref_to_ptr(k)               NULL
 401#define is_key_possessed(k)             0
 402#define key_fsuid_changed(t)            do { } while(0)
 403#define key_fsgid_changed(t)            do { } while(0)
 404#define key_init()                      do { } while(0)
 405
 406#endif /* CONFIG_KEYS */
 407#endif /* __KERNEL__ */
 408#endif /* _LINUX_KEY_H */
 409