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
  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        struct rb_node          serial_node;
 128        struct key_type         *type;          /* type of key */
 129        struct rw_semaphore     sem;            /* change vs change sem */
 130        struct key_user         *user;          /* owner of this key */
 131        void                    *security;      /* security data for this key */
 132        union {
 133                time_t          expiry;         /* time at which key expires (or 0) */
 134                time_t          revoked_at;     /* time at which key was revoked */
 135        };
 136        uid_t                   uid;
 137        gid_t                   gid;
 138        key_perm_t              perm;           /* access permissions */
 139        unsigned short          quotalen;       /* length added to quota */
 140        unsigned short          datalen;        /* payload data length
 141                                                 * - may not match RCU dereferenced payload
 142                                                 * - payload should contain own length
 143                                                 */
 144
 145#ifdef KEY_DEBUGGING
 146        unsigned                magic;
 147#define KEY_DEBUG_MAGIC         0x18273645u
 148#define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 149#endif
 150
 151        unsigned long           flags;          /* status flags (change with bitops) */
 152#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 153#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 154#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 155#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 156#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 157#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 158
 159        /* the description string
 160         * - this is used to match a key against search criteria
 161         * - this should be a printable string
 162         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 163         */
 164        char                    *description;
 165
 166        /* type specific data
 167         * - this is used by the keyring type to index the name
 168         */
 169        union {
 170                struct list_head        link;
 171                unsigned long           x[2];
 172                void                    *p[2];
 173                int                     reject_error;
 174        } type_data;
 175
 176        /* key data
 177         * - this is used to hold the data actually used in cryptography or
 178         *   whatever
 179         */
 180        union {
 181                unsigned long           value;
 182                void __rcu              *rcudata;
 183                void                    *data;
 184                struct keyring_list __rcu *subscriptions;
 185        } payload;
 186};
 187
 188extern struct key *key_alloc(struct key_type *type,
 189                             const char *desc,
 190                             uid_t uid, gid_t gid,
 191                             const struct cred *cred,
 192                             key_perm_t perm,
 193                             unsigned long flags);
 194
 195
 196#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 197#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 198#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 199
 200extern void key_revoke(struct key *key);
 201extern void key_put(struct key *key);
 202
 203static inline struct key *key_get(struct key *key)
 204{
 205        if (key)
 206                atomic_inc(&key->usage);
 207        return key;
 208}
 209
 210static inline void key_ref_put(key_ref_t key_ref)
 211{
 212        key_put(key_ref_to_ptr(key_ref));
 213}
 214
 215extern struct key *request_key(struct key_type *type,
 216                               const char *description,
 217                               const char *callout_info);
 218
 219extern struct key *request_key_with_auxdata(struct key_type *type,
 220                                            const char *description,
 221                                            const void *callout_info,
 222                                            size_t callout_len,
 223                                            void *aux);
 224
 225extern struct key *request_key_async(struct key_type *type,
 226                                     const char *description,
 227                                     const void *callout_info,
 228                                     size_t callout_len);
 229
 230extern struct key *request_key_async_with_auxdata(struct key_type *type,
 231                                                  const char *description,
 232                                                  const void *callout_info,
 233                                                  size_t callout_len,
 234                                                  void *aux);
 235
 236extern int wait_for_key_construction(struct key *key, bool intr);
 237
 238extern int key_validate(struct key *key);
 239
 240extern key_ref_t key_create_or_update(key_ref_t keyring,
 241                                      const char *type,
 242                                      const char *description,
 243                                      const void *payload,
 244                                      size_t plen,
 245                                      key_perm_t perm,
 246                                      unsigned long flags);
 247
 248extern int key_update(key_ref_t key,
 249                      const void *payload,
 250                      size_t plen);
 251
 252extern int key_link(struct key *keyring,
 253                    struct key *key);
 254
 255extern int key_unlink(struct key *keyring,
 256                      struct key *key);
 257
 258extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 259                                 const struct cred *cred,
 260                                 unsigned long flags,
 261                                 struct key *dest);
 262
 263extern int keyring_clear(struct key *keyring);
 264
 265extern key_ref_t keyring_search(key_ref_t keyring,
 266                                struct key_type *type,
 267                                const char *description);
 268
 269extern int keyring_add_key(struct key *keyring,
 270                           struct key *key);
 271
 272extern struct key *key_lookup(key_serial_t id);
 273
 274static inline key_serial_t key_serial(const struct key *key)
 275{
 276        return key ? key->serial : 0;
 277}
 278
 279/**
 280 * key_is_instantiated - Determine if a key has been positively instantiated
 281 * @key: The key to check.
 282 *
 283 * Return true if the specified key has been positively instantiated, false
 284 * otherwise.
 285 */
 286static inline bool key_is_instantiated(const struct key *key)
 287{
 288        return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 289                !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 290}
 291
 292#define rcu_dereference_key(KEY)                                        \
 293        (rcu_dereference_protected((KEY)->payload.rcudata,              \
 294                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 295
 296#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 297        (rcu_assign_pointer((KEY)->payload.rcudata, PAYLOAD))
 298
 299#ifdef CONFIG_SYSCTL
 300extern ctl_table key_sysctls[];
 301#endif
 302
 303extern void key_replace_session_keyring(void);
 304
 305/*
 306 * the userspace interface
 307 */
 308extern int install_thread_keyring_to_cred(struct cred *cred);
 309extern void key_fsuid_changed(struct task_struct *tsk);
 310extern void key_fsgid_changed(struct task_struct *tsk);
 311extern void key_init(void);
 312
 313#else /* CONFIG_KEYS */
 314
 315#define key_validate(k)                 0
 316#define key_serial(k)                   0
 317#define key_get(k)                      ({ NULL; })
 318#define key_revoke(k)                   do { } while(0)
 319#define key_put(k)                      do { } while(0)
 320#define key_ref_put(k)                  do { } while(0)
 321#define make_key_ref(k, p)              NULL
 322#define key_ref_to_ptr(k)               NULL
 323#define is_key_possessed(k)             0
 324#define key_fsuid_changed(t)            do { } while(0)
 325#define key_fsgid_changed(t)            do { } while(0)
 326#define key_init()                      do { } while(0)
 327#define key_replace_session_keyring()   do { } while(0)
 328
 329#endif /* CONFIG_KEYS */
 330#endif /* __KERNEL__ */
 331#endif /* _LINUX_KEY_H */
 332