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