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         } type_data;
 164
 165         /* key data
 166          * - this is used to hold the data actually used in cryptography or
 167          *   whatever
 168          */
 169         union {
 170                 unsigned long           value;
 171                 void                    *data;
 172                 struct keyring_list     *subscriptions;
 173         } payload;
 174 };
 175
 176 /*****************************************************************************/
 177 /*
 178  * kernel managed key type definition
 179  */
 180 typedef int (*request_key_actor_t)(struct key *key, struct key *authkey,
 181                                    const char *op, void *aux);
 182
 183 struct key_type {
 184         /* name of the type */
 185         const char *name;
 186
 187         /* default payload length for quota precalculation (optional)
 188          * - this can be used instead of calling key_payload_reserve(), that
 189          *   function only needs to be called if the real datalen is different
 190          */
 191         size_t def_datalen;
 192
 193         /* instantiate a key of this type
 194          * - this method should call key_payload_reserve() to determine if the
 195          *   user's quota will hold the payload
 196          */
 197         int (*instantiate)(struct key *key, const void *data, size_t datalen);
 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 some of the data from a key on revokation (optional)
 210          * - the key's semaphore will be write-locked by the caller
 211          */
 212         void (*revoke)(struct key *key);
 213
 214         /* clear the data from a key (optional) */
 215         void (*destroy)(struct key *key);
 216
 217         /* describe a key */
 218         void (*describe)(const struct key *key, struct seq_file *p);
 219
 220         /* read a key's data (optional)
 221          * - permission checks will be done by the caller
 222          * - the key's semaphore will be readlocked by the caller
 223          * - should return the amount of data that could be read, no matter how
 224          *   much is copied into the buffer
 225          * - shouldn't do the copy if the buffer is NULL
 226          */
 227         long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 228
 229         /* handle request_key() for this type instead of invoking
 230          * /sbin/request-key (optional)
 231          * - key is the key to instantiate
 232          * - authkey is the authority to assume when instantiating this key
 233          * - op is the operation to be done, usually "create"
 234          * - the call must not return until the instantiation process has run
 235          *   its course
 236          */
 237         request_key_actor_t request_key;
 238
 239         /* internal fields */
 240         struct list_head        link;           /* link in types list */
 241 };
 242
 243 extern struct key_type key_type_keyring;
 244
 245 extern int register_key_type(struct key_type *ktype);
 246 extern void unregister_key_type(struct key_type *ktype);
 247
 248 extern struct key *key_alloc(struct key_type *type,
 249                              const char *desc,
 250                              uid_t uid, gid_t gid,
 251                              struct task_struct *ctx,
 252                              key_perm_t perm,
 253                              unsigned long flags);
 254
 255
 256 #define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 257 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 258 #define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 259
 260 extern int key_payload_reserve(struct key *key, size_t datalen);
 261 extern int key_instantiate_and_link(struct key *key,
 262                                     const void *data,
 263                                     size_t datalen,
 264                                     struct key *keyring,
 265                                     struct key *instkey);
 266 extern int key_negate_and_link(struct key *key,
 267                                unsigned timeout,
 268                                struct key *keyring,
 269                                struct key *instkey);
 270 extern void key_revoke(struct key *key);
 271 extern void key_put(struct key *key);
 272
 273 static inline struct key *key_get(struct key *key)
 274 {
 275         if (key)
 276                 atomic_inc(&key->usage);
 277         return key;
 278 }
 279
 280 static inline void key_ref_put(key_ref_t key_ref)
 281 {
 282         key_put(key_ref_to_ptr(key_ref));
 283 }
 284
 285 extern struct key *request_key(struct key_type *type,
 286                                const char *description,
 287                                const char *callout_info);
 288
 289 extern struct key *request_key_with_auxdata(struct key_type *type,
 290                                             const char *description,
 291                                             const char *callout_info,
 292                                             void *aux);
 293
 294 extern int key_validate(struct key *key);
 295
 296 extern key_ref_t key_create_or_update(key_ref_t keyring,
 297                                       const char *type,
 298                                       const char *description,
 299                                       const void *payload,
 300                                       size_t plen,
 301                                       unsigned long flags);
 302
 303 extern int key_update(key_ref_t key,
 304                       const void *payload,
 305                       size_t plen);
 306
 307 extern int key_link(struct key *keyring,
 308                     struct key *key);
 309
 310 extern int key_unlink(struct key *keyring,
 311                       struct key *key);
 312
 313 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 314                                  struct task_struct *ctx,
 315                                  unsigned long flags,
 316                                  struct key *dest);
 317
 318 extern int keyring_clear(struct key *keyring);
 319
 320 extern key_ref_t keyring_search(key_ref_t keyring,
 321                                 struct key_type *type,
 322                                 const char *description);
 323
 324 extern int keyring_add_key(struct key *keyring,
 325                            struct key *key);
 326
 327 extern struct key *key_lookup(key_serial_t id);
 328
 329 extern void keyring_replace_payload(struct key *key, void *replacement);
 330
 331 #define key_serial(key) ((key) ? (key)->serial : 0)
 332
 333 /*
 334  * the userspace interface
 335  */
 336 extern struct key root_user_keyring, root_session_keyring;
 337 extern int alloc_uid_keyring(struct user_struct *user,
 338                              struct task_struct *ctx);
 339 extern void switch_uid_keyring(struct user_struct *new_user);
 340 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
 341 extern int copy_thread_group_keys(struct task_struct *tsk);
 342 extern void exit_keys(struct task_struct *tsk);
 343 extern void exit_thread_group_keys(struct signal_struct *tg);
 344 extern int suid_keys(struct task_struct *tsk);
 345 extern int exec_keys(struct task_struct *tsk);
 346 extern void key_fsuid_changed(struct task_struct *tsk);
 347 extern void key_fsgid_changed(struct task_struct *tsk);
 348 extern void key_init(void);
 349
 350 #define __install_session_keyring(tsk, keyring)                 \
 351 ({                                                              \
 352         struct key *old_session = tsk->signal->session_keyring; \
 353         tsk->signal->session_keyring = keyring;                 \
 354         old_session;                                            \
 355 })
 356
 357 #else /* CONFIG_KEYS */
 358
 359 #define key_validate(k)                 0
 360 #define key_serial(k)                   0
 361 #define key_get(k)                      ({ NULL; })
 362 #define key_put(k)                      do { } while(0)
 363 #define key_ref_put(k)                  do { } while(0)
 364 #define make_key_ref(k)                 ({ NULL; })
 365 #define key_ref_to_ptr(k)               ({ NULL; })
 366 #define is_key_possessed(k)             0
 367 #define alloc_uid_keyring(u,c)          0
 368 #define switch_uid_keyring(u)           do { } while(0)
 369 #define __install_session_keyring(t, k) ({ NULL; })
 370 #define copy_keys(f,t)                  0
 371 #define copy_thread_group_keys(t)       0
 372 #define exit_keys(t)                    do { } while(0)
 373 #define exit_thread_group_keys(tg)      do { } while(0)
 374 #define suid_keys(t)                    do { } while(0)
 375 #define exec_keys(t)                    do { } while(0)
 376 #define key_fsuid_changed(t)            do { } while(0)
 377 #define key_fsgid_changed(t)            do { } while(0)
 378 #define key_init()                      do { } while(0)
 379
 380 /* Initial keyrings */
 381 extern struct key root_user_keyring;
 382 extern struct key root_session_keyring;
 383
 384 #endif /* CONFIG_KEYS */
 385 #endif /* __KERNEL__ */
 386 #endif /* _LINUX_KEY_H */