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_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  39 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  40 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  41 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  42 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  43 #define KEY_POS_ALL     0x1f000000
  44
  45 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  46 #define KEY_USR_READ    0x00020000
  47 #define KEY_USR_WRITE   0x00040000
  48 #define KEY_USR_SEARCH  0x00080000
  49 #define KEY_USR_LINK    0x00100000
  50 #define KEY_USR_ALL     0x001f0000
  51
  52 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  53 #define KEY_GRP_READ    0x00000200
  54 #define KEY_GRP_WRITE   0x00000400
  55 #define KEY_GRP_SEARCH  0x00000800
  56 #define KEY_GRP_LINK    0x00001000
  57 #define KEY_GRP_ALL     0x00001f00
  58
  59 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  60 #define KEY_OTH_READ    0x00000002
  61 #define KEY_OTH_WRITE   0x00000004
  62 #define KEY_OTH_SEARCH  0x00000008
  63 #define KEY_OTH_LINK    0x00000010
  64 #define KEY_OTH_ALL     0x0000001f
  65
  66 struct seq_file;
  67 struct user_struct;
  68 struct signal_struct;
  69
  70 struct key_type;
  71 struct key_owner;
  72 struct keyring_list;
  73 struct keyring_name;
  74
  75 /*****************************************************************************/
  76 /*
  77  * key reference with possession attribute handling
  78  *
  79  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  80  * defined. This is because we abuse the bottom bit of the reference to carry a
  81  * flag to indicate whether the calling process possesses that key in one of
  82  * its keyrings.
  83  *
  84  * the key_ref_t has been made a separate type so that the compiler can reject
  85  * attempts to dereference it without proper conversion.
  86  *
  87  * the three functions are used to assemble and disassemble references
  88  */
  89 typedef struct __key_reference_with_attributes *key_ref_t;
  90
  91 static inline key_ref_t make_key_ref(const struct key *key,
  92                                      unsigned long possession)
  93 {
  94         return (key_ref_t) ((unsigned long) key | possession);
  95 }
  96
  97 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
  98 {
  99         return (struct key *) ((unsigned long) key_ref & ~1UL);
 100 }
 101
 102 static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 103 {
 104         return (unsigned long) key_ref & 1UL;
 105 }
 106
 107 /*****************************************************************************/
 108 /*
 109  * authentication token / access credential / keyring
 110  * - types of key include:
 111  *   - keyrings
 112  *   - disk encryption IDs
 113  *   - Kerberos TGTs and tickets
 114  */
 115 struct key {
 116         atomic_t                usage;          /* number of references */
 117         key_serial_t            serial;         /* key serial number */
 118         struct rb_node          serial_node;
 119         struct key_type         *type;          /* type of key */
 120         struct rw_semaphore     sem;            /* change vs change sem */
 121         struct key_user         *user;          /* owner of this key */
 122         time_t                  expiry;         /* time at which key expires (or 0) */
 123         uid_t                   uid;
 124         gid_t                   gid;
 125         key_perm_t              perm;           /* access permissions */
 126         unsigned short          quotalen;       /* length added to quota */
 127         unsigned short          datalen;        /* payload data length
 128                                                  * - may not match RCU dereferenced payload
 129                                                  * - payload should contain own length
 130                                                  */
 131
 132 #ifdef KEY_DEBUGGING
 133         unsigned                magic;
 134 #define KEY_DEBUG_MAGIC         0x18273645u
 135 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 136 #endif
 137
 138         unsigned long           flags;          /* status flags (change with bitops) */
 139 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 140 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 141 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 142 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 143 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 144 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 145
 146         /* the description string
 147          * - this is used to match a key against search criteria
 148          * - this should be a printable string
 149          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 150          */
 151         char                    *description;
 152
 153         /* type specific data
 154          * - this is used by the keyring type to index the name
 155          */
 156         union {
 157                 struct list_head        link;
 158         } type_data;
 159
 160         /* key data
 161          * - this is used to hold the data actually used in cryptography or
 162          *   whatever
 163          */
 164         union {
 165                 unsigned long           value;
 166                 void                    *data;
 167                 struct keyring_list     *subscriptions;
 168         } payload;
 169 };
 170
 171 /*****************************************************************************/
 172 /*
 173  * kernel managed key type definition
 174  */
 175 struct key_type {
 176         /* name of the type */
 177         const char *name;
 178
 179         /* default payload length for quota precalculation (optional)
 180          * - this can be used instead of calling key_payload_reserve(), that
 181          *   function only needs to be called if the real datalen is different
 182          */
 183         size_t def_datalen;
 184
 185         /* instantiate a key of this type
 186          * - this method should call key_payload_reserve() to determine if the
 187          *   user's quota will hold the payload
 188          */
 189         int (*instantiate)(struct key *key, const void *data, size_t datalen);
 190
 191         /* duplicate a key of this type (optional)
 192          * - the source key will be locked against change
 193          * - the new description will be attached
 194          * - the quota will have been adjusted automatically from
 195          *   source->quotalen
 196          */
 197         int (*duplicate)(struct key *key, const struct key *source);
 198
 199         /* update a key of this type (optional)
 200          * - this method should call key_payload_reserve() to recalculate the
 201          *   quota consumption
 202          * - the key must be locked against read when modifying
 203          */
 204         int (*update)(struct key *key, const void *data, size_t datalen);
 205
 206         /* match a key against a description */
 207         int (*match)(const struct key *key, const void *desc);
 208
 209         /* clear the data from a key (optional) */
 210         void (*destroy)(struct key *key);
 211
 212         /* describe a key */
 213         void (*describe)(const struct key *key, struct seq_file *p);
 214
 215         /* read a key's data (optional)
 216          * - permission checks will be done by the caller
 217          * - the key's semaphore will be readlocked by the caller
 218          * - should return the amount of data that could be read, no matter how
 219          *   much is copied into the buffer
 220          * - shouldn't do the copy if the buffer is NULL
 221          */
 222         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 223
 224         /* internal fields */
 225         struct list_head        link;           /* link in types list */
 226 };
 227
 228 extern struct key_type key_type_keyring;
 229
 230 extern int register_key_type(struct key_type *ktype);
 231 extern void unregister_key_type(struct key_type *ktype);
 232
 233 extern struct key *key_alloc(struct key_type *type,
 234                              const char *desc,
 235                              uid_t uid, gid_t gid, key_perm_t perm,
 236                              int not_in_quota);
 237 extern int key_payload_reserve(struct key *key, size_t datalen);
 238 extern int key_instantiate_and_link(struct key *key,
 239                                     const void *data,
 240                                     size_t datalen,
 241                                     struct key *keyring,
 242                                     struct key *instkey);
 243 extern int key_negate_and_link(struct key *key,
 244                                unsigned timeout,
 245                                struct key *keyring,
 246                                struct key *instkey);
 247 extern void key_revoke(struct key *key);
 248 extern void key_put(struct key *key);
 249
 250 static inline struct key *key_get(struct key *key)
 251 {
 252         if (key)
 253                 atomic_inc(&key->usage);
 254         return key;
 255 }
 256
 257 static inline void key_ref_put(key_ref_t key_ref)
 258 {
 259         key_put(key_ref_to_ptr(key_ref));
 260 }
 261
 262 extern struct key *request_key(struct key_type *type,
 263                                const char *description,
 264                                const char *callout_info);
 265
 266 extern int key_validate(struct key *key);
 267
 268 extern key_ref_t key_create_or_update(key_ref_t keyring,
 269                                       const char *type,
 270                                       const char *description,
 271                                       const void *payload,
 272                                       size_t plen,
 273                                       int not_in_quota);
 274
 275 extern int key_update(key_ref_t key,
 276                       const void *payload,
 277                       size_t plen);
 278
 279 extern int key_link(struct key *keyring,
 280                     struct key *key);
 281
 282 extern int key_unlink(struct key *keyring,
 283                       struct key *key);
 284
 285 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 286                                  int not_in_quota, struct key *dest);
 287
 288 extern int keyring_clear(struct key *keyring);
 289
 290 extern key_ref_t keyring_search(key_ref_t keyring,
 291                                 struct key_type *type,
 292                                 const char *description);
 293
 294 extern int keyring_add_key(struct key *keyring,
 295                            struct key *key);
 296
 297 extern struct key *key_lookup(key_serial_t id);
 298
 299 extern void keyring_replace_payload(struct key *key, void *replacement);
 300
 301 #define key_serial(key) ((key) ? (key)->serial : 0)
 302
 303 /*
 304  * the userspace interface
 305  */
 306 extern struct key root_user_keyring, root_session_keyring;
 307 extern int alloc_uid_keyring(struct user_struct *user);
 308 extern void switch_uid_keyring(struct user_struct *new_user);
 309 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
 310 extern int copy_thread_group_keys(struct task_struct *tsk);
 311 extern void exit_keys(struct task_struct *tsk);
 312 extern void exit_thread_group_keys(struct signal_struct *tg);
 313 extern int suid_keys(struct task_struct *tsk);
 314 extern int exec_keys(struct task_struct *tsk);
 315 extern void key_fsuid_changed(struct task_struct *tsk);
 316 extern void key_fsgid_changed(struct task_struct *tsk);
 317 extern void key_init(void);
 318
 319 #define __install_session_keyring(tsk, keyring)                 \
 320 ({                                                              \
 321         struct key *old_session = tsk->signal->session_keyring; \
 322         tsk->signal->session_keyring = keyring;                 \
 323         old_session;                                            \
 324 })
 325
 326 #else /* CONFIG_KEYS */
 327
 328 #define key_validate(k)                 0
 329 #define key_serial(k)                   0
 330 #define key_get(k)                      ({ NULL; })
 331 #define key_put(k)                      do { } while(0)
 332 #define key_ref_put(k)                  do { } while(0)
 333 #define make_key_ref(k)                 ({ NULL; })
 334 #define key_ref_to_ptr(k)               ({ NULL; })
 335 #define is_key_possessed(k)             0
 336 #define alloc_uid_keyring(u)            0
 337 #define switch_uid_keyring(u)           do { } while(0)
 338 #define __install_session_keyring(t, k) ({ NULL; })
 339 #define copy_keys(f,t)                  0
 340 #define copy_thread_group_keys(t)       0
 341 #define exit_keys(t)                    do { } while(0)
 342 #define exit_thread_group_keys(tg)      do { } while(0)
 343 #define suid_keys(t)                    do { } while(0)
 344 #define exec_keys(t)                    do { } while(0)
 345 #define key_fsuid_changed(t)            do { } while(0)
 346 #define key_fsgid_changed(t)            do { } while(0)
 347 #define key_init()                      do { } while(0)
 348
 349 #endif /* CONFIG_KEYS */
 350 #endif /* __KERNEL__ */
 351 #endif /* _LINUX_KEY_H */