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
  92union key_payload {
  93        void __rcu              *rcu_data0;
  94        void                    *data[4];
  95};
  96
  97/*****************************************************************************/
  98/*
  99 * key reference with possession attribute handling
 100 *
 101 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 102 * defined. This is because we abuse the bottom bit of the reference to carry a
 103 * flag to indicate whether the calling process possesses that key in one of
 104 * its keyrings.
 105 *
 106 * the key_ref_t has been made a separate type so that the compiler can reject
 107 * attempts to dereference it without proper conversion.
 108 *
 109 * the three functions are used to assemble and disassemble references
 110 */
 111typedef struct __key_reference_with_attributes *key_ref_t;
 112
 113static inline key_ref_t make_key_ref(const struct key *key,
 114                                     bool possession)
 115{
 116        return (key_ref_t) ((unsigned long) key | possession);
 117}
 118
 119static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 120{
 121        return (struct key *) ((unsigned long) key_ref & ~1UL);
 122}
 123
 124static inline bool is_key_possessed(const key_ref_t key_ref)
 125{
 126        return (unsigned long) key_ref & 1UL;
 127}
 128
 129/*****************************************************************************/
 130/*
 131 * authentication token / access credential / keyring
 132 * - types of key include:
 133 *   - keyrings
 134 *   - disk encryption IDs
 135 *   - Kerberos TGTs and tickets
 136 */
 137struct key {
 138        atomic_t                usage;          /* number of references */
 139        key_serial_t            serial;         /* key serial number */
 140        union {
 141                struct list_head graveyard_link;
 142                struct rb_node  serial_node;
 143        };
 144        struct rw_semaphore     sem;            /* change vs change sem */
 145        struct key_user         *user;          /* owner of this key */
 146        void                    *security;      /* security data for this key */
 147        union {
 148                time_t          expiry;         /* time at which key expires (or 0) */
 149                time_t          revoked_at;     /* time at which key was revoked */
 150        };
 151        time_t                  last_used_at;   /* last time used for LRU keyring discard */
 152        kuid_t                  uid;
 153        kgid_t                  gid;
 154        key_perm_t              perm;           /* access permissions */
 155        unsigned short          quotalen;       /* length added to quota */
 156        unsigned short          datalen;        /* payload data length
 157                                                 * - may not match RCU dereferenced payload
 158                                                 * - payload should contain own length
 159                                                 */
 160
 161#ifdef KEY_DEBUGGING
 162        unsigned                magic;
 163#define KEY_DEBUG_MAGIC         0x18273645u
 164#define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 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_BUILTIN        8       /* set if key is built in to the kernel */
 177#define KEY_FLAG_ROOT_CAN_INVAL 9       /* set if key can be invalidated by root without permission */
 178#define KEY_FLAG_KEEP           10      /* set if key should not be removed */
 179
 180        /* the key type and key description string
 181         * - the desc is used to match a key against search criteria
 182         * - it should be a printable string
 183         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 184         */
 185        union {
 186                struct keyring_index_key index_key;
 187                struct {
 188                        struct key_type *type;          /* type of key */
 189                        char            *description;
 190                };
 191        };
 192
 193        /* key data
 194         * - this is used to hold the data actually used in cryptography or
 195         *   whatever
 196         */
 197        union {
 198                union key_payload payload;
 199                struct {
 200                        /* Keyring bits */
 201                        struct list_head name_link;
 202                        struct assoc_array keys;
 203                };
 204                int reject_error;
 205        };
 206
 207        /* This is set on a keyring to restrict the addition of a link to a key
 208         * to it.  If this method isn't provided then it is assumed that the
 209         * keyring is open to any addition.  It is ignored for non-keyring
 210         * keys.
 211         *
 212         * This is intended for use with rings of trusted keys whereby addition
 213         * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 214         * overrides this, allowing the kernel to add extra keys without
 215         * restriction.
 216         */
 217        int (*restrict_link)(struct key *keyring,
 218                             const struct key_type *type,
 219                             const union key_payload *payload);
 220};
 221
 222extern struct key *key_alloc(struct key_type *type,
 223                             const char *desc,
 224                             kuid_t uid, kgid_t gid,
 225                             const struct cred *cred,
 226                             key_perm_t perm,
 227                             unsigned long flags,
 228                             int (*restrict_link)(struct key *,
 229                                                  const struct key_type *,
 230                                                  const union key_payload *));
 231
 232
 233#define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 234#define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 235#define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 236#define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 237#define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 238
 239extern void key_revoke(struct key *key);
 240extern void key_invalidate(struct key *key);
 241extern void key_put(struct key *key);
 242
 243static inline struct key *__key_get(struct key *key)
 244{
 245        atomic_inc(&key->usage);
 246        return key;
 247}
 248
 249static inline struct key *key_get(struct key *key)
 250{
 251        return key ? __key_get(key) : key;
 252}
 253
 254static inline void key_ref_put(key_ref_t key_ref)
 255{
 256        key_put(key_ref_to_ptr(key_ref));
 257}
 258
 259extern struct key *request_key(struct key_type *type,
 260                               const char *description,
 261                               const char *callout_info);
 262
 263extern struct key *request_key_with_auxdata(struct key_type *type,
 264                                            const char *description,
 265                                            const void *callout_info,
 266                                            size_t callout_len,
 267                                            void *aux);
 268
 269extern struct key *request_key_async(struct key_type *type,
 270                                     const char *description,
 271                                     const void *callout_info,
 272                                     size_t callout_len);
 273
 274extern struct key *request_key_async_with_auxdata(struct key_type *type,
 275                                                  const char *description,
 276                                                  const void *callout_info,
 277                                                  size_t callout_len,
 278                                                  void *aux);
 279
 280extern int wait_for_key_construction(struct key *key, bool intr);
 281
 282extern int key_validate(const struct key *key);
 283
 284extern key_ref_t key_create_or_update(key_ref_t keyring,
 285                                      const char *type,
 286                                      const char *description,
 287                                      const void *payload,
 288                                      size_t plen,
 289                                      key_perm_t perm,
 290                                      unsigned long flags);
 291
 292extern int key_update(key_ref_t key,
 293                      const void *payload,
 294                      size_t plen);
 295
 296extern int key_link(struct key *keyring,
 297                    struct key *key);
 298
 299extern int key_unlink(struct key *keyring,
 300                      struct key *key);
 301
 302extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 303                                 const struct cred *cred,
 304                                 key_perm_t perm,
 305                                 unsigned long flags,
 306                                 int (*restrict_link)(struct key *,
 307                                                      const struct key_type *,
 308                                                      const union key_payload *),
 309                                 struct key *dest);
 310
 311extern int restrict_link_reject(struct key *keyring,
 312                                const struct key_type *type,
 313                                const union key_payload *payload);
 314
 315extern int keyring_clear(struct key *keyring);
 316
 317extern key_ref_t keyring_search(key_ref_t keyring,
 318                                struct key_type *type,
 319                                const char *description);
 320
 321extern int keyring_add_key(struct key *keyring,
 322                           struct key *key);
 323
 324extern struct key *key_lookup(key_serial_t id);
 325
 326static inline key_serial_t key_serial(const struct key *key)
 327{
 328        return key ? key->serial : 0;
 329}
 330
 331extern void key_set_timeout(struct key *, unsigned);
 332
 333/*
 334 * The permissions required on a key that we're looking up.
 335 */
 336#define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 337#define KEY_NEED_READ   0x02    /* Require permission to read content */
 338#define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 339#define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 340#define KEY_NEED_LINK   0x10    /* Require permission to link */
 341#define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 342#define KEY_NEED_ALL    0x3f    /* All the above permissions */
 343
 344/**
 345 * key_is_instantiated - Determine if a key has been positively instantiated
 346 * @key: The key to check.
 347 *
 348 * Return true if the specified key has been positively instantiated, false
 349 * otherwise.
 350 */
 351static inline bool key_is_instantiated(const struct key *key)
 352{
 353        return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 354                !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 355}
 356
 357#define rcu_dereference_key(KEY)                                        \
 358        (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 359                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 360
 361#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 362do {                                                                    \
 363        rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 364} while (0)
 365
 366#ifdef CONFIG_SYSCTL
 367extern struct ctl_table key_sysctls[];
 368#endif
 369/*
 370 * the userspace interface
 371 */
 372extern int install_thread_keyring_to_cred(struct cred *cred);
 373extern void key_fsuid_changed(struct task_struct *tsk);
 374extern void key_fsgid_changed(struct task_struct *tsk);
 375extern void key_init(void);
 376
 377#else /* CONFIG_KEYS */
 378
 379#define key_validate(k)                 0
 380#define key_serial(k)                   0
 381#define key_get(k)                      ({ NULL; })
 382#define key_revoke(k)                   do { } while(0)
 383#define key_invalidate(k)               do { } while(0)
 384#define key_put(k)                      do { } while(0)
 385#define key_ref_put(k)                  do { } while(0)
 386#define make_key_ref(k, p)              NULL
 387#define key_ref_to_ptr(k)               NULL
 388#define is_key_possessed(k)             0
 389#define key_fsuid_changed(t)            do { } while(0)
 390#define key_fsgid_changed(t)            do { } while(0)
 391#define key_init()                      do { } while(0)
 392
 393#endif /* CONFIG_KEYS */
 394#endif /* __KERNEL__ */
 395#endif /* _LINUX_KEY_H */
 396