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_SETATTR 0x20000000      /* possessor can set key attributes */
  44 #define KEY_POS_ALL     0x3f000000
  45
  46 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  47 #define KEY_USR_READ    0x00020000
  48 #define KEY_USR_WRITE   0x00040000
  49 #define KEY_USR_SEARCH  0x00080000
  50 #define KEY_USR_LINK    0x00100000
  51 #define KEY_USR_SETATTR 0x00200000
  52 #define KEY_USR_ALL     0x003f0000
  53
  54 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  55 #define KEY_GRP_READ    0x00000200
  56 #define KEY_GRP_WRITE   0x00000400
  57 #define KEY_GRP_SEARCH  0x00000800
  58 #define KEY_GRP_LINK    0x00001000
  59 #define KEY_GRP_SETATTR 0x00002000
  60 #define KEY_GRP_ALL     0x00003f00
  61
  62 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  63 #define KEY_OTH_READ    0x00000002
  64 #define KEY_OTH_WRITE   0x00000004
  65 #define KEY_OTH_SEARCH  0x00000008
  66 #define KEY_OTH_LINK    0x00000010
  67 #define KEY_OTH_SETATTR 0x00000020
  68 #define KEY_OTH_ALL     0x0000003f
  69
  70 struct seq_file;
  71 struct user_struct;
  72 struct signal_struct;
  73
  74 struct key_type;
  75 struct key_owner;
  76 struct keyring_list;
  77 struct keyring_name;
  78
  79 /*****************************************************************************/
  80 /*
  81  * key reference with possession attribute handling
  82  *
  83  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  84  * defined. This is because we abuse the bottom bit of the reference to carry a
  85  * flag to indicate whether the calling process possesses that key in one of
  86  * its keyrings.
  87  *
  88  * the key_ref_t has been made a separate type so that the compiler can reject
  89  * attempts to dereference it without proper conversion.
  90  *
  91  * the three functions are used to assemble and disassemble references
  92  */
  93 typedef struct __key_reference_with_attributes *key_ref_t;
  94
  95 static inline key_ref_t make_key_ref(const struct key *key,
  96                                      unsigned long possession)
  97 {
  98         return (key_ref_t) ((unsigned long) key | possession);
  99 }
 100
 101 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 102 {
 103         return (struct key *) ((unsigned long) key_ref & ~1UL);
 104 }
 105
 106 static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 107 {
 108         return (unsigned long) key_ref & 1UL;
 109 }
 110
 111 /*****************************************************************************/
 112 /*
 113  * authentication token / access credential / keyring
 114  * - types of key include:
 115  *   - keyrings
 116  *   - disk encryption IDs
 117  *   - Kerberos TGTs and tickets
 118  */
 119 struct key {
 120         atomic_t                usage;          /* number of references */
 121         key_serial_t            serial;         /* key serial number */
 122         struct rb_node          serial_node;
 123         struct key_type         *type;          /* type of key */
 124         struct rw_semaphore     sem;            /* change vs change sem */
 125         struct key_user         *user;          /* owner of this key */
 126         void                    *security;      /* security data for this key */
 127         time_t                  expiry;         /* time at which key expires (or 0) */
 128         uid_t                   uid;
 129         gid_t                   gid;
 130         key_perm_t              perm;           /* access permissions */
 131         unsigned short          quotalen;       /* length added to quota */
 132         unsigned short          datalen;        /* payload data length
 133                                                  * - may not match RCU dereferenced payload
 134                                                  * - payload should contain own length
 135                                                  */
 136
 137 #ifdef KEY_DEBUGGING
 138         unsigned                magic;
 139 #define KEY_DEBUG_MAGIC         0x18273645u
 140 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 141 #endif
 142
 143         unsigned long           flags;          /* status flags (change with bitops) */
 144 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 145 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 146 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 147 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 148 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 149 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 150
 151         /* the description string
 152          * - this is used to match a key against search criteria
 153          * - this should be a printable string
 154          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 155          */
 156         char                    *description;
 157
 158         /* type specific data
 159          * - this is used by the keyring type to index the name
 160          */
 161         union {
 162                 struct list_head        link;
 163                 unsigned long           x[2];
 164                 void                    *p[2];
 165         } type_data;
 166
 167         /* key data
 168          * - this is used to hold the data actually used in cryptography or
 169          *   whatever
 170          */
 171         union {
 172                 unsigned long           value;
 173                 void                    *data;
 174                 struct keyring_list     *subscriptions;
 175         } payload;
 176 };
 177
 178 /*****************************************************************************/
 179 /*
 180  * kernel managed key type definition
 181  */
 182 typedef int (*request_key_actor_t)(struct key *key, struct key *authkey,
 183                                    const char *op, void *aux);
 184
 185 struct key_type {
 186         /* name of the type */
 187         const char *name;
 188
 189         /* default payload length for quota precalculation (optional)
 190          * - this can be used instead of calling key_payload_reserve(), that
 191          *   function only needs to be called if the real datalen is different
 192          */
 193         size_t def_datalen;
 194
 195         /* instantiate a key of this type
 196          * - this method should call key_payload_reserve() to determine if the
 197          *   user's quota will hold the payload
 198          */
 199         int (*instantiate)(struct key *key, const void *data, size_t datalen);
 200
 201         /* update a key of this type (optional)
 202          * - this method should call key_payload_reserve() to recalculate the
 203          *   quota consumption
 204          * - the key must be locked against read when modifying
 205          */
 206         int (*update)(struct key *key, const void *data, size_t datalen);
 207
 208         /* match a key against a description */
 209         int (*match)(const struct key *key, const void *desc);
 210
 211         /* clear some of the data from a key on revokation (optional)
 212          * - the key's semaphore will be write-locked by the caller
 213          */
 214         void (*revoke)(struct key *key);
 215
 216         /* clear the data from a key (optional) */
 217         void (*destroy)(struct key *key);
 218
 219         /* describe a key */
 220         void (*describe)(const struct key *key, struct seq_file *p);
 221
 222         /* read a key's data (optional)
 223          * - permission checks will be done by the caller
 224          * - the key's semaphore will be readlocked by the caller
 225          * - should return the amount of data that could be read, no matter how
 226          *   much is copied into the buffer
 227          * - shouldn't do the copy if the buffer is NULL
 228          */
 229         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 230
 231         /* handle request_key() for this type instead of invoking
 232          * /sbin/request-key (optional)
 233          * - key is the key to instantiate
 234          * - authkey is the authority to assume when instantiating this key
 235          * - op is the operation to be done, usually "create"
 236          * - the call must not return until the instantiation process has run
 237          *   its course
 238          */
 239         request_key_actor_t request_key;
 240
 241         /* internal fields */
 242         struct list_head        link;           /* link in types list */
 243 };
 244
 245 extern struct key_type key_type_keyring;
 246
 247 extern int register_key_type(struct key_type *ktype);
 248 extern void unregister_key_type(struct key_type *ktype);
 249
 250 extern struct key *key_alloc(struct key_type *type,
 251                              const char *desc,
 252                              uid_t uid, gid_t gid,
 253                              struct task_struct *ctx,
 254                              key_perm_t perm,
 255                              unsigned long flags);
 256
 257
 258 #define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 259 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 260 #define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 261
 262 extern int key_payload_reserve(struct key *key, size_t datalen);
 263 extern int key_instantiate_and_link(struct key *key,
 264                                     const void *data,
 265                                     size_t datalen,
 266                                     struct key *keyring,
 267                                     struct key *instkey);
 268 extern int key_negate_and_link(struct key *key,
 269                                unsigned timeout,
 270                                struct key *keyring,
 271                                struct key *instkey);
 272 extern void key_revoke(struct key *key);
 273 extern void key_put(struct key *key);
 274
 275 static inline struct key *key_get(struct key *key)
 276 {
 277         if (key)
 278                 atomic_inc(&key->usage);
 279         return key;
 280 }
 281
 282 static inline void key_ref_put(key_ref_t key_ref)
 283 {
 284         key_put(key_ref_to_ptr(key_ref));
 285 }
 286
 287 extern struct key *request_key(struct key_type *type,
 288                                const char *description,
 289                                const char *callout_info);
 290
 291 extern struct key *request_key_with_auxdata(struct key_type *type,
 292                                             const char *description,
 293                                             const char *callout_info,
 294                                             void *aux);
 295
 296 extern int key_validate(struct key *key);
 297
 298 extern key_ref_t key_create_or_update(key_ref_t keyring,
 299                                       const char *type,
 300                                       const char *description,
 301                                       const void *payload,
 302                                       size_t plen,
 303                                       unsigned long flags);
 304
 305 extern int key_update(key_ref_t key,
 306                       const void *payload,
 307                       size_t plen);
 308
 309 extern int key_link(struct key *keyring,
 310                     struct key *key);
 311
 312 extern int key_unlink(struct key *keyring,
 313                       struct key *key);
 314
 315 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 316                                  struct task_struct *ctx,
 317                                  unsigned long flags,
 318                                  struct key *dest);
 319
 320 extern int keyring_clear(struct key *keyring);
 321
 322 extern key_ref_t keyring_search(key_ref_t keyring,
 323                                 struct key_type *type,
 324                                 const char *description);
 325
 326 extern int keyring_add_key(struct key *keyring,
 327                            struct key *key);
 328
 329 extern struct key *key_lookup(key_serial_t id);
 330
 331 extern void keyring_replace_payload(struct key *key, void *replacement);
 332
 333 #define key_serial(key) ((key) ? (key)->serial : 0)
 334
 335 /*
 336  * the userspace interface
 337  */
 338 extern struct key root_user_keyring, root_session_keyring;
 339 extern int alloc_uid_keyring(struct user_struct *user,
 340                              struct task_struct *ctx);
 341 extern void switch_uid_keyring(struct user_struct *new_user);
 342 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
 343 extern int copy_thread_group_keys(struct task_struct *tsk);
 344 extern void exit_keys(struct task_struct *tsk);
 345 extern void exit_thread_group_keys(struct signal_struct *tg);
 346 extern int suid_keys(struct task_struct *tsk);
 347 extern int exec_keys(struct task_struct *tsk);
 348 extern void key_fsuid_changed(struct task_struct *tsk);
 349 extern void key_fsgid_changed(struct task_struct *tsk);
 350 extern void key_init(void);
 351
 352 #define __install_session_keyring(tsk, keyring)                 \
 353 ({                                                              \
 354         struct key *old_session = tsk->signal->session_keyring; \
 355         tsk->signal->session_keyring = keyring;                 \
 356         old_session;                                            \
 357 })
 358
 359 #else /* CONFIG_KEYS */
 360
 361 #define key_validate(k)                 0
 362 #define key_serial(k)                   0
 363 #define key_get(k)                      ({ NULL; })
 364 #define key_put(k)                      do { } while(0)
 365 #define key_ref_put(k)                  do { } while(0)
 366 #define make_key_ref(k)                 ({ NULL; })
 367 #define key_ref_to_ptr(k)               ({ NULL; })
 368 #define is_key_possessed(k)             0
 369 #define alloc_uid_keyring(u,c)          0
 370 #define switch_uid_keyring(u)           do { } while(0)
 371 #define __install_session_keyring(t, k) ({ NULL; })
 372 #define copy_keys(f,t)                  0
 373 #define copy_thread_group_keys(t)       0
 374 #define exit_keys(t)                    do { } while(0)
 375 #define exit_thread_group_keys(tg)      do { } while(0)
 376 #define suid_keys(t)                    do { } while(0)
 377 #define exec_keys(t)                    do { } while(0)
 378 #define key_fsuid_changed(t)            do { } while(0)
 379 #define key_fsgid_changed(t)            do { } while(0)
 380 #define key_init()                      do { } while(0)
 381
 382 /* Initial keyrings */
 383 extern struct key root_user_keyring;
 384 extern struct key root_session_keyring;
 385
 386 #endif /* CONFIG_KEYS */
 387 #endif /* __KERNEL__ */
 388 #endif /* _LINUX_KEY_H */