include/linux/key.h

   1 /* key.h: authentication token and access key management
   2  *
   3  * Copyright (C) 2004 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/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 <asm/atomic.h>
  23
  24 #ifdef __KERNEL__
  25
  26 /* key handle serial number */
  27 typedef int32_t key_serial_t;
  28
  29 /* key handle permissions mask */
  30 typedef uint32_t key_perm_t;
  31
  32 struct key;
  33
  34 #ifdef CONFIG_KEYS
  35
  36 #undef KEY_DEBUGGING
  37
  38 #define KEY_USR_VIEW    0x00010000      /* user can view a key's attributes */
  39 #define KEY_USR_READ    0x00020000      /* user can read key payload / view keyring */
  40 #define KEY_USR_WRITE   0x00040000      /* user can update key payload / add link to keyring */
  41 #define KEY_USR_SEARCH  0x00080000      /* user can find a key in search / search a keyring */
  42 #define KEY_USR_LINK    0x00100000      /* user can create a link to a key/keyring */
  43 #define KEY_USR_ALL     0x001f0000
  44
  45 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  46 #define KEY_GRP_READ    0x00000200
  47 #define KEY_GRP_WRITE   0x00000400
  48 #define KEY_GRP_SEARCH  0x00000800
  49 #define KEY_GRP_LINK    0x00001000
  50 #define KEY_GRP_ALL     0x00001f00
  51
  52 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  53 #define KEY_OTH_READ    0x00000002
  54 #define KEY_OTH_WRITE   0x00000004
  55 #define KEY_OTH_SEARCH  0x00000008
  56 #define KEY_OTH_LINK    0x00000010
  57 #define KEY_OTH_ALL     0x0000001f
  58
  59 struct seq_file;
  60 struct user_struct;
  61 struct signal_struct;
  62
  63 struct key_type;
  64 struct key_owner;
  65 struct keyring_list;
  66 struct keyring_name;
  67
  68 /*****************************************************************************/
  69 /*
  70  * authentication token / access credential / keyring
  71  * - types of key include:
  72  *   - keyrings
  73  *   - disk encryption IDs
  74  *   - Kerberos TGTs and tickets
  75  */
  76 struct key {
  77         atomic_t                usage;          /* number of references */
  78         key_serial_t            serial;         /* key serial number */
  79         struct rb_node          serial_node;
  80         struct key_type         *type;          /* type of key */
  81         struct rw_semaphore     sem;            /* change vs change sem */
  82         struct key_user         *user;          /* owner of this key */
  83         time_t                  expiry;         /* time at which key expires (or 0) */
  84         uid_t                   uid;
  85         gid_t                   gid;
  86         key_perm_t              perm;           /* access permissions */
  87         unsigned short          quotalen;       /* length added to quota */
  88         unsigned short          datalen;        /* payload data length
  89                                                  * - may not match RCU dereferenced payload
  90                                                  * - payload should contain own length
  91                                                  */
  92
  93 #ifdef KEY_DEBUGGING
  94         unsigned                magic;
  95 #define KEY_DEBUG_MAGIC         0x18273645u
  96 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
  97 #endif
  98
  99         unsigned long           flags;          /* status flags (change with bitops) */
 100 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 101 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 102 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 103 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 104 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 105 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 106
 107         /* the description string
 108          * - this is used to match a key against search criteria
 109          * - this should be a printable string
 110          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 111          */
 112         char                    *description;
 113
 114         /* type specific data
 115          * - this is used by the keyring type to index the name
 116          */
 117         union {
 118                 struct list_head        link;
 119         } type_data;
 120
 121         /* key data
 122          * - this is used to hold the data actually used in cryptography or
 123          *   whatever
 124          */
 125         union {
 126                 unsigned long           value;
 127                 void                    *data;
 128                 struct keyring_list     *subscriptions;
 129         } payload;
 130 };
 131
 132 /*****************************************************************************/
 133 /*
 134  * kernel managed key type definition
 135  */
 136 struct key_type {
 137         /* name of the type */
 138         const char *name;
 139
 140         /* default payload length for quota precalculation (optional)
 141          * - this can be used instead of calling key_payload_reserve(), that
 142          *   function only needs to be called if the real datalen is different
 143          */
 144         size_t def_datalen;
 145
 146         /* instantiate a key of this type
 147          * - this method should call key_payload_reserve() to determine if the
 148          *   user's quota will hold the payload
 149          */
 150         int (*instantiate)(struct key *key, const void *data, size_t datalen);
 151
 152         /* duplicate a key of this type (optional)
 153          * - the source key will be locked against change
 154          * - the new description will be attached
 155          * - the quota will have been adjusted automatically from
 156          *   source->quotalen
 157          */
 158         int (*duplicate)(struct key *key, const struct key *source);
 159
 160         /* update a key of this type (optional)
 161          * - this method should call key_payload_reserve() to recalculate the
 162          *   quota consumption
 163          * - the key must be locked against read when modifying
 164          */
 165         int (*update)(struct key *key, const void *data, size_t datalen);
 166
 167         /* match a key against a description */
 168         int (*match)(const struct key *key, const void *desc);
 169
 170         /* clear the data from a key (optional) */
 171         void (*destroy)(struct key *key);
 172
 173         /* describe a key */
 174         void (*describe)(const struct key *key, struct seq_file *p);
 175
 176         /* read a key's data (optional)
 177          * - permission checks will be done by the caller
 178          * - the key's semaphore will be readlocked by the caller
 179          * - should return the amount of data that could be read, no matter how
 180          *   much is copied into the buffer
 181          * - shouldn't do the copy if the buffer is NULL
 182          */
 183         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 184
 185         /* internal fields */
 186         struct list_head        link;           /* link in types list */
 187 };
 188
 189 extern struct key_type key_type_keyring;
 190
 191 extern int register_key_type(struct key_type *ktype);
 192 extern void unregister_key_type(struct key_type *ktype);
 193
 194 extern struct key *key_alloc(struct key_type *type,
 195                              const char *desc,
 196                              uid_t uid, gid_t gid, key_perm_t perm,
 197                              int not_in_quota);
 198 extern int key_payload_reserve(struct key *key, size_t datalen);
 199 extern int key_instantiate_and_link(struct key *key,
 200                                     const void *data,
 201                                     size_t datalen,
 202                                     struct key *keyring,
 203                                     struct key *instkey);
 204 extern int key_negate_and_link(struct key *key,
 205                                unsigned timeout,
 206                                struct key *keyring,
 207                                struct key *instkey);
 208 extern void key_revoke(struct key *key);
 209 extern void key_put(struct key *key);
 210
 211 static inline struct key *key_get(struct key *key)
 212 {
 213         if (key)
 214                 atomic_inc(&key->usage);
 215         return key;
 216 }
 217
 218 extern struct key *request_key(struct key_type *type,
 219                                const char *description,
 220                                const char *callout_info);
 221
 222 extern int key_validate(struct key *key);
 223
 224 extern struct key *key_create_or_update(struct key *keyring,
 225                                         const char *type,
 226                                         const char *description,
 227                                         const void *payload,
 228                                         size_t plen,
 229                                         int not_in_quota);
 230
 231 extern int key_update(struct key *key,
 232                       const void *payload,
 233                       size_t plen);
 234
 235 extern int key_link(struct key *keyring,
 236                     struct key *key);
 237
 238 extern int key_unlink(struct key *keyring,
 239                       struct key *key);
 240
 241 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 242                                  int not_in_quota, struct key *dest);
 243
 244 extern int keyring_clear(struct key *keyring);
 245
 246 extern struct key *keyring_search(struct key *keyring,
 247                                   struct key_type *type,
 248                                   const char *description);
 249
 250 extern int keyring_add_key(struct key *keyring,
 251                            struct key *key);
 252
 253 extern struct key *key_lookup(key_serial_t id);
 254
 255 extern void keyring_replace_payload(struct key *key, void *replacement);
 256
 257 #define key_serial(key) ((key) ? (key)->serial : 0)
 258
 259 /*
 260  * the userspace interface
 261  */
 262 extern struct key root_user_keyring, root_session_keyring;
 263 extern int alloc_uid_keyring(struct user_struct *user);
 264 extern void switch_uid_keyring(struct user_struct *new_user);
 265 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
 266 extern int copy_thread_group_keys(struct task_struct *tsk);
 267 extern void exit_keys(struct task_struct *tsk);
 268 extern void exit_thread_group_keys(struct signal_struct *tg);
 269 extern int suid_keys(struct task_struct *tsk);
 270 extern int exec_keys(struct task_struct *tsk);
 271 extern void key_fsuid_changed(struct task_struct *tsk);
 272 extern void key_fsgid_changed(struct task_struct *tsk);
 273 extern void key_init(void);
 274
 275 #define __install_session_keyring(tsk, keyring)                 \
 276 ({                                                              \
 277         struct key *old_session = tsk->signal->session_keyring; \
 278         tsk->signal->session_keyring = keyring;                 \
 279         old_session;                                            \
 280 })
 281
 282 #else /* CONFIG_KEYS */
 283
 284 #define key_validate(k)                 0
 285 #define key_serial(k)                   0
 286 #define key_get(k)                      ({ NULL; })
 287 #define key_put(k)                      do { } while(0)
 288 #define alloc_uid_keyring(u)            0
 289 #define switch_uid_keyring(u)           do { } while(0)
 290 #define __install_session_keyring(t, k) ({ NULL; })
 291 #define copy_keys(f,t)                  0
 292 #define copy_thread_group_keys(t)       0
 293 #define exit_keys(t)                    do { } while(0)
 294 #define exit_thread_group_keys(tg)      do { } while(0)
 295 #define suid_keys(t)                    do { } while(0)
 296 #define exec_keys(t)                    do { } while(0)
 297 #define key_fsuid_changed(t)            do { } while(0)
 298 #define key_fsgid_changed(t)            do { } while(0)
 299 #define key_init()                      do { } while(0)
 300
 301 #endif /* CONFIG_KEYS */
 302 #endif /* __KERNEL__ */
 303 #endif /* _LINUX_KEY_H */