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#include <linux/uidgid.h>
  28
  29/* key handle serial number */
  30typedef int32_t key_serial_t;
  31
  32/* key handle permissions mask */
  33typedef uint32_t key_perm_t;
  34
  35struct key;
  36
  37#ifdef CONFIG_KEYS
  38
  39#undef KEY_DEBUGGING
  40
  41#define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  42#define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  43#define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  44#define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  45#define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  46#define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  47#define KEY_POS_ALL     0x3f000000
  48
  49#define KEY_USR_VIEW    0x00010000      /* user permissions... */
  50#define KEY_USR_READ    0x00020000
  51#define KEY_USR_WRITE   0x00040000
  52#define KEY_USR_SEARCH  0x00080000
  53#define KEY_USR_LINK    0x00100000
  54#define KEY_USR_SETATTR 0x00200000
  55#define KEY_USR_ALL     0x003f0000
  56
  57#define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  58#define KEY_GRP_READ    0x00000200
  59#define KEY_GRP_WRITE   0x00000400
  60#define KEY_GRP_SEARCH  0x00000800
  61#define KEY_GRP_LINK    0x00001000
  62#define KEY_GRP_SETATTR 0x00002000
  63#define KEY_GRP_ALL     0x00003f00
  64
  65#define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  66#define KEY_OTH_READ    0x00000002
  67#define KEY_OTH_WRITE   0x00000004
  68#define KEY_OTH_SEARCH  0x00000008
  69#define KEY_OTH_LINK    0x00000010
  70#define KEY_OTH_SETATTR 0x00000020
  71#define KEY_OTH_ALL     0x0000003f
  72
  73#define KEY_PERM_UNDEF  0xffffffff
  74
  75struct seq_file;
  76struct user_struct;
  77struct signal_struct;
  78struct cred;
  79
  80struct key_type;
  81struct key_owner;
  82struct keyring_list;
  83struct keyring_name;
  84
  85/*****************************************************************************/
  86/*
  87 * key reference with possession attribute handling
  88 *
  89 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  90 * defined. This is because we abuse the bottom bit of the reference to carry a
  91 * flag to indicate whether the calling process possesses that key in one of
  92 * its keyrings.
  93 *
  94 * the key_ref_t has been made a separate type so that the compiler can reject
  95 * attempts to dereference it without proper conversion.
  96 *
  97 * the three functions are used to assemble and disassemble references
  98 */
  99typedef struct __key_reference_with_attributes *key_ref_t;
 100
 101static inline key_ref_t make_key_ref(const struct key *key,
 102                                     unsigned long possession)
 103{
 104        return (key_ref_t) ((unsigned long) key | possession);
 105}
 106
 107static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 108{
 109        return (struct key *) ((unsigned long) key_ref & ~1UL);
 110}
 111
 112static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 113{
 114        return (unsigned long) key_ref & 1UL;
 115}
 116
 117/*****************************************************************************/
 118/*
 119 * authentication token / access credential / keyring
 120 * - types of key include:
 121 *   - keyrings
 122 *   - disk encryption IDs
 123 *   - Kerberos TGTs and tickets
 124 */
 125struct key {
 126        atomic_t                usage;          /* number of references */
 127        key_serial_t            serial;         /* key serial number */
 128        union {
 129                struct list_head graveyard_link;
 130                struct rb_node  serial_node;
 131        };
 132        struct key_type         *type;          /* type of key */
 133        struct rw_semaphore     sem;            /* change vs change sem */
 134        struct key_user         *user;          /* owner of this key */
 135        void                    *security;      /* security data for this key */
 136        union {
 137                time_t          expiry;         /* time at which key expires (or 0) */
 138                time_t          revoked_at;     /* time at which key was revoked */
 139        };
 140        time_t                  last_used_at;   /* last time used for LRU keyring discard */
 141        kuid_t                  uid;
 142        kgid_t                  gid;
 143        key_perm_t              perm;           /* access permissions */
 144        unsigned short          quotalen;       /* length added to quota */
 145        unsigned short          datalen;        /* payload data length
 146                                                 * - may not match RCU dereferenced payload
 147                                                 * - payload should contain own length
 148                                                 */
 149
 150#ifdef KEY_DEBUGGING
 151        unsigned                magic;
 152#define KEY_DEBUG_MAGIC         0x18273645u
 153#define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 154#endif
 155
 156        unsigned long           flags;          /* status flags (change with bitops) */
 157#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 158#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 159#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 160#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 161#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 162#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 163#define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 164#define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 165
 166        /* the description string
 167         * - this is used to match a key against search criteria
 168         * - this should be a printable string
 169         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 170         */
 171        char                    *description;
 172
 173        /* type specific data
 174         * - this is used by the keyring type to index the name
 175         */
 176        union {
 177                struct list_head        link;
 178                unsigned long           x[2];
 179                void                    *p[2];
 180                int                     reject_error;
 181        } type_data;
 182
 183        /* key data
 184         * - this is used to hold the data actually used in cryptography or
 185         *   whatever
 186         */
 187        union {
 188                unsigned long           value;
 189                void __rcu              *rcudata;
 190                void                    *data;
 191                struct keyring_list __rcu *subscriptions;
 192        } payload;
 193};
 194
 195extern struct key *key_alloc(struct key_type *type,
 196                             const char *desc,
 197                             kuid_t uid, kgid_t gid,
 198                             const struct cred *cred,
 199                             key_perm_t perm,
 200                             unsigned long flags);
 201
 202
 203#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 204#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 205#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 206
 207extern void key_revoke(struct key *key);
 208extern void key_invalidate(struct key *key);
 209extern void key_put(struct key *key);
 210
 211static inline struct key *key_get(struct key *key)
 212{
 213        if (key)
 214                atomic_inc(&key->usage);
 215        return key;
 216}
 217
 218static inline void key_ref_put(key_ref_t key_ref)
 219{
 220        key_put(key_ref_to_ptr(key_ref));
 221}
 222
 223extern struct key *request_key(struct key_type *type,
 224                               const char *description,
 225                               const char *callout_info);
 226
 227extern struct key *request_key_with_auxdata(struct key_type *type,
 228                                            const char *description,
 229                                            const void *callout_info,
 230                                            size_t callout_len,
 231                                            void *aux);
 232
 233extern struct key *request_key_async(struct key_type *type,
 234                                     const char *description,
 235                                     const void *callout_info,
 236                                     size_t callout_len);
 237
 238extern struct key *request_key_async_with_auxdata(struct key_type *type,
 239                                                  const char *description,
 240                                                  const void *callout_info,
 241                                                  size_t callout_len,
 242                                                  void *aux);
 243
 244extern int wait_for_key_construction(struct key *key, bool intr);
 245
 246extern int key_validate(const struct key *key);
 247
 248extern key_ref_t key_create_or_update(key_ref_t keyring,
 249                                      const char *type,
 250                                      const char *description,
 251                                      const void *payload,
 252                                      size_t plen,
 253                                      key_perm_t perm,
 254                                      unsigned long flags);
 255
 256extern int key_update(key_ref_t key,
 257                      const void *payload,
 258                      size_t plen);
 259
 260extern int key_link(struct key *keyring,
 261                    struct key *key);
 262
 263extern int key_unlink(struct key *keyring,
 264                      struct key *key);
 265
 266extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 267                                 const struct cred *cred,
 268                                 unsigned long flags,
 269                                 struct key *dest);
 270
 271extern int keyring_clear(struct key *keyring);
 272
 273extern key_ref_t keyring_search(key_ref_t keyring,
 274                                struct key_type *type,
 275                                const char *description);
 276
 277extern int keyring_add_key(struct key *keyring,
 278                           struct key *key);
 279
 280extern struct key *key_lookup(key_serial_t id);
 281
 282static inline key_serial_t key_serial(const struct key *key)
 283{
 284        return key ? key->serial : 0;
 285}
 286
 287extern void key_set_timeout(struct key *, unsigned);
 288
 289/**
 290 * key_is_instantiated - Determine if a key has been positively instantiated
 291 * @key: The key to check.
 292 *
 293 * Return true if the specified key has been positively instantiated, false
 294 * otherwise.
 295 */
 296static inline bool key_is_instantiated(const struct key *key)
 297{
 298        return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 299                !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 300}
 301
 302#define rcu_dereference_key(KEY)                                        \
 303        (rcu_dereference_protected((KEY)->payload.rcudata,              \
 304                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 305
 306#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 307do {                                                                    \
 308        rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD));          \
 309} while (0)
 310
 311#ifdef CONFIG_SYSCTL
 312extern ctl_table key_sysctls[];
 313#endif
 314/*
 315 * the userspace interface
 316 */
 317extern int install_thread_keyring_to_cred(struct cred *cred);
 318extern void key_fsuid_changed(struct task_struct *tsk);
 319extern void key_fsgid_changed(struct task_struct *tsk);
 320extern void key_init(void);
 321
 322#else /* CONFIG_KEYS */
 323
 324#define key_validate(k)                 0
 325#define key_serial(k)                   0
 326#define key_get(k)                      ({ NULL; })
 327#define key_revoke(k)                   do { } while(0)
 328#define key_invalidate(k)               do { } while(0)
 329#define key_put(k)                      do { } while(0)
 330#define key_ref_put(k)                  do { } while(0)
 331#define make_key_ref(k, p)              NULL
 332#define key_ref_to_ptr(k)               NULL
 333#define is_key_possessed(k)             0
 334#define key_fsuid_changed(t)            do { } while(0)
 335#define key_fsgid_changed(t)            do { } while(0)
 336#define key_init()                      do { } while(0)
 337
 338#endif /* CONFIG_KEYS */
 339#endif /* __KERNEL__ */
 340#endif /* _LINUX_KEY_H */
 341
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