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 #include <linux/assoc_array.h>
  26
  27 #ifdef __KERNEL__
  28 #include <linux/uidgid.h>
  29
  30 /* key handle serial number */
  31 typedef int32_t key_serial_t;
  32
  33 /* key handle permissions mask */
  34 typedef uint32_t key_perm_t;
  35
  36 struct key;
  37
  38 #ifdef CONFIG_KEYS
  39
  40 #undef KEY_DEBUGGING
  41
  42 #define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  43 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  44 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  45 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  46 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  47 #define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  48 #define KEY_POS_ALL     0x3f000000
  49
  50 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  51 #define KEY_USR_READ    0x00020000
  52 #define KEY_USR_WRITE   0x00040000
  53 #define KEY_USR_SEARCH  0x00080000
  54 #define KEY_USR_LINK    0x00100000
  55 #define KEY_USR_SETATTR 0x00200000
  56 #define KEY_USR_ALL     0x003f0000
  57
  58 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  59 #define KEY_GRP_READ    0x00000200
  60 #define KEY_GRP_WRITE   0x00000400
  61 #define KEY_GRP_SEARCH  0x00000800
  62 #define KEY_GRP_LINK    0x00001000
  63 #define KEY_GRP_SETATTR 0x00002000
  64 #define KEY_GRP_ALL     0x00003f00
  65
  66 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  67 #define KEY_OTH_READ    0x00000002
  68 #define KEY_OTH_WRITE   0x00000004
  69 #define KEY_OTH_SEARCH  0x00000008
  70 #define KEY_OTH_LINK    0x00000010
  71 #define KEY_OTH_SETATTR 0x00000020
  72 #define KEY_OTH_ALL     0x0000003f
  73
  74 #define KEY_PERM_UNDEF  0xffffffff
  75
  76 struct seq_file;
  77 struct user_struct;
  78 struct signal_struct;
  79 struct cred;
  80
  81 struct key_type;
  82 struct key_owner;
  83 struct keyring_list;
  84 struct keyring_name;
  85
  86 struct keyring_index_key {
  87         struct key_type         *type;
  88         const char              *description;
  89         size_t                  desc_len;
  90 };
  91
  92 /*****************************************************************************/
  93 /*
  94  * key reference with possession attribute handling
  95  *
  96  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  97  * defined. This is because we abuse the bottom bit of the reference to carry a
  98  * flag to indicate whether the calling process possesses that key in one of
  99  * its keyrings.
 100  *
 101  * the key_ref_t has been made a separate type so that the compiler can reject
 102  * attempts to dereference it without proper conversion.
 103  *
 104  * the three functions are used to assemble and disassemble references
 105  */
 106 typedef struct __key_reference_with_attributes *key_ref_t;
 107
 108 static inline key_ref_t make_key_ref(const struct key *key,
 109                                      bool possession)
 110 {
 111         return (key_ref_t) ((unsigned long) key | possession);
 112 }
 113
 114 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 115 {
 116         return (struct key *) ((unsigned long) key_ref & ~1UL);
 117 }
 118
 119 static inline bool is_key_possessed(const key_ref_t key_ref)
 120 {
 121         return (unsigned long) key_ref & 1UL;
 122 }
 123
 124 /*****************************************************************************/
 125 /*
 126  * authentication token / access credential / keyring
 127  * - types of key include:
 128  *   - keyrings
 129  *   - disk encryption IDs
 130  *   - Kerberos TGTs and tickets
 131  */
 132 struct key {
 133         atomic_t                usage;          /* number of references */
 134         key_serial_t            serial;         /* key serial number */
 135         union {
 136                 struct list_head graveyard_link;
 137                 struct rb_node  serial_node;
 138         };
 139         struct rw_semaphore     sem;            /* change vs change sem */
 140         struct key_user         *user;          /* owner of this key */
 141         void                    *security;      /* security data for this key */
 142         union {
 143                 time_t          expiry;         /* time at which key expires (or 0) */
 144                 time_t          revoked_at;     /* time at which key was revoked */
 145         };
 146         time_t                  last_used_at;   /* last time used for LRU keyring discard */
 147         kuid_t                  uid;
 148         kgid_t                  gid;
 149         key_perm_t              perm;           /* access permissions */
 150         unsigned short          quotalen;       /* length added to quota */
 151         unsigned short          datalen;        /* payload data length
 152                                                  * - may not match RCU dereferenced payload
 153                                                  * - payload should contain own length
 154                                                  */
 155
 156 #ifdef KEY_DEBUGGING
 157         unsigned                magic;
 158 #define KEY_DEBUG_MAGIC         0x18273645u
 159 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 160 #endif
 161
 162         unsigned long           flags;          /* status flags (change with bitops) */
 163 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 164 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 165 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 166 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 167 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 168 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 169 #define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 170 #define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 171 #define KEY_FLAG_TRUSTED        8       /* set if key is trusted */
 172 #define KEY_FLAG_TRUSTED_ONLY   9       /* set if keyring only accepts links to trusted keys */
 173
 174         /* the key type and key description string
 175          * - the desc is used to match a key against search criteria
 176          * - it should be a printable string
 177          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 178          */
 179         union {
 180                 struct keyring_index_key index_key;
 181                 struct {
 182                         struct key_type *type;          /* type of key */
 183                         char            *description;
 184                 };
 185         };
 186
 187         /* type specific data
 188          * - this is used by the keyring type to index the name
 189          */
 190         union {
 191                 struct list_head        link;
 192                 unsigned long           x[2];
 193                 void                    *p[2];
 194                 int                     reject_error;
 195         } type_data;
 196
 197         /* key data
 198          * - this is used to hold the data actually used in cryptography or
 199          *   whatever
 200          */
 201         union {
 202                 union {
 203                         unsigned long           value;
 204                         void __rcu              *rcudata;
 205                         void                    *data;
 206                         void                    *data2[2];
 207                 } payload;
 208                 struct assoc_array keys;
 209         };
 210 };
 211
 212 extern struct key *key_alloc(struct key_type *type,
 213                              const char *desc,
 214                              kuid_t uid, kgid_t gid,
 215                              const struct cred *cred,
 216                              key_perm_t perm,
 217                              unsigned long flags);
 218
 219
 220 #define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 221 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 222 #define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 223 #define KEY_ALLOC_TRUSTED       0x0004  /* Key should be flagged as trusted */
 224
 225 extern void key_revoke(struct key *key);
 226 extern void key_invalidate(struct key *key);
 227 extern void key_put(struct key *key);
 228
 229 static inline struct key *__key_get(struct key *key)
 230 {
 231         atomic_inc(&key->usage);
 232         return key;
 233 }
 234
 235 static inline struct key *key_get(struct key *key)
 236 {
 237         return key ? __key_get(key) : key;
 238 }
 239
 240 static inline void key_ref_put(key_ref_t key_ref)
 241 {
 242         key_put(key_ref_to_ptr(key_ref));
 243 }
 244
 245 extern struct key *request_key(struct key_type *type,
 246                                const char *description,
 247                                const char *callout_info);
 248
 249 extern struct key *request_key_with_auxdata(struct key_type *type,
 250                                             const char *description,
 251                                             const void *callout_info,
 252                                             size_t callout_len,
 253                                             void *aux);
 254
 255 extern struct key *request_key_async(struct key_type *type,
 256                                      const char *description,
 257                                      const void *callout_info,
 258                                      size_t callout_len);
 259
 260 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 261                                                   const char *description,
 262                                                   const void *callout_info,
 263                                                   size_t callout_len,
 264                                                   void *aux);
 265
 266 extern int wait_for_key_construction(struct key *key, bool intr);
 267
 268 extern int key_validate(const struct key *key);
 269
 270 extern key_ref_t key_create_or_update(key_ref_t keyring,
 271                                       const char *type,
 272                                       const char *description,
 273                                       const void *payload,
 274                                       size_t plen,
 275                                       key_perm_t perm,
 276                                       unsigned long flags);
 277
 278 extern int key_update(key_ref_t key,
 279                       const void *payload,
 280                       size_t plen);
 281
 282 extern int key_link(struct key *keyring,
 283                     struct key *key);
 284
 285 extern int key_unlink(struct key *keyring,
 286                       struct key *key);
 287
 288 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 289                                  const struct cred *cred,
 290                                  key_perm_t perm,
 291                                  unsigned long flags,
 292                                  struct key *dest);
 293
 294 extern int keyring_clear(struct key *keyring);
 295
 296 extern key_ref_t keyring_search(key_ref_t keyring,
 297                                 struct key_type *type,
 298                                 const char *description);
 299
 300 extern int keyring_add_key(struct key *keyring,
 301                            struct key *key);
 302
 303 extern struct key *key_lookup(key_serial_t id);
 304
 305 static inline key_serial_t key_serial(const struct key *key)
 306 {
 307         return key ? key->serial : 0;
 308 }
 309
 310 extern void key_set_timeout(struct key *, unsigned);
 311
 312 /**
 313  * key_is_instantiated - Determine if a key has been positively instantiated
 314  * @key: The key to check.
 315  *
 316  * Return true if the specified key has been positively instantiated, false
 317  * otherwise.
 318  */
 319 static inline bool key_is_instantiated(const struct key *key)
 320 {
 321         return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 322                 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 323 }
 324
 325 #define rcu_dereference_key(KEY)                                        \
 326         (rcu_dereference_protected((KEY)->payload.rcudata,              \
 327                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 328
 329 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 330 do {                                                                    \
 331         rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD));          \
 332 } while (0)
 333
 334 #ifdef CONFIG_SYSCTL
 335 extern ctl_table key_sysctls[];
 336 #endif
 337 /*
 338  * the userspace interface
 339  */
 340 extern int install_thread_keyring_to_cred(struct cred *cred);
 341 extern void key_fsuid_changed(struct task_struct *tsk);
 342 extern void key_fsgid_changed(struct task_struct *tsk);
 343 extern void key_init(void);
 344
 345 #else /* CONFIG_KEYS */
 346
 347 #define key_validate(k)                 0
 348 #define key_serial(k)                   0
 349 #define key_get(k)                      ({ NULL; })
 350 #define key_revoke(k)                   do { } while(0)
 351 #define key_invalidate(k)               do { } while(0)
 352 #define key_put(k)                      do { } while(0)
 353 #define key_ref_put(k)                  do { } while(0)
 354 #define make_key_ref(k, p)              NULL
 355 #define key_ref_to_ptr(k)               NULL
 356 #define is_key_possessed(k)             0
 357 #define key_fsuid_changed(t)            do { } while(0)
 358 #define key_fsgid_changed(t)            do { } while(0)
 359 #define key_init()                      do { } while(0)
 360
 361 #endif /* CONFIG_KEYS */
 362 #endif /* __KERNEL__ */
 363 #endif /* _LINUX_KEY_H */