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/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 <asm/atomic.h>
  24
  25 #ifdef __KERNEL__
  26
  27 /* key handle serial number */
  28 typedef int32_t key_serial_t;
  29
  30 /* key handle permissions mask */
  31 typedef uint32_t key_perm_t;
  32
  33 struct key;
  34
  35 #ifdef CONFIG_KEYS
  36
  37 #undef KEY_DEBUGGING
  38
  39 #define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  40 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  41 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  42 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  43 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  44 #define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  45 #define KEY_POS_ALL     0x3f000000
  46
  47 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  48 #define KEY_USR_READ    0x00020000
  49 #define KEY_USR_WRITE   0x00040000
  50 #define KEY_USR_SEARCH  0x00080000
  51 #define KEY_USR_LINK    0x00100000
  52 #define KEY_USR_SETATTR 0x00200000
  53 #define KEY_USR_ALL     0x003f0000
  54
  55 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  56 #define KEY_GRP_READ    0x00000200
  57 #define KEY_GRP_WRITE   0x00000400
  58 #define KEY_GRP_SEARCH  0x00000800
  59 #define KEY_GRP_LINK    0x00001000
  60 #define KEY_GRP_SETATTR 0x00002000
  61 #define KEY_GRP_ALL     0x00003f00
  62
  63 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  64 #define KEY_OTH_READ    0x00000002
  65 #define KEY_OTH_WRITE   0x00000004
  66 #define KEY_OTH_SEARCH  0x00000008
  67 #define KEY_OTH_LINK    0x00000010
  68 #define KEY_OTH_SETATTR 0x00000020
  69 #define KEY_OTH_ALL     0x0000003f
  70
  71 #define KEY_PERM_UNDEF  0xffffffff
  72
  73 struct seq_file;
  74 struct user_struct;
  75 struct signal_struct;
  76
  77 struct key_type;
  78 struct key_owner;
  79 struct keyring_list;
  80 struct keyring_name;
  81
  82 /*****************************************************************************/
  83 /*
  84  * key reference with possession attribute handling
  85  *
  86  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  87  * defined. This is because we abuse the bottom bit of the reference to carry a
  88  * flag to indicate whether the calling process possesses that key in one of
  89  * its keyrings.
  90  *
  91  * the key_ref_t has been made a separate type so that the compiler can reject
  92  * attempts to dereference it without proper conversion.
  93  *
  94  * the three functions are used to assemble and disassemble references
  95  */
  96 typedef struct __key_reference_with_attributes *key_ref_t;
  97
  98 static inline key_ref_t make_key_ref(const struct key *key,
  99                                      unsigned long possession)
 100 {
 101         return (key_ref_t) ((unsigned long) key | possession);
 102 }
 103
 104 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 105 {
 106         return (struct key *) ((unsigned long) key_ref & ~1UL);
 107 }
 108
 109 static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 110 {
 111         return (unsigned long) key_ref & 1UL;
 112 }
 113
 114 /*****************************************************************************/
 115 /*
 116  * authentication token / access credential / keyring
 117  * - types of key include:
 118  *   - keyrings
 119  *   - disk encryption IDs
 120  *   - Kerberos TGTs and tickets
 121  */
 122 struct key {
 123         atomic_t                usage;          /* number of references */
 124         key_serial_t            serial;         /* key serial number */
 125         struct rb_node          serial_node;
 126         struct key_type         *type;          /* type of key */
 127         struct rw_semaphore     sem;            /* change vs change sem */
 128         struct key_user         *user;          /* owner of this key */
 129         void                    *security;      /* security data for this key */
 130         time_t                  expiry;         /* time at which key expires (or 0) */
 131         uid_t                   uid;
 132         gid_t                   gid;
 133         key_perm_t              perm;           /* access permissions */
 134         unsigned short          quotalen;       /* length added to quota */
 135         unsigned short          datalen;        /* payload data length
 136                                                  * - may not match RCU dereferenced payload
 137                                                  * - payload should contain own length
 138                                                  */
 139
 140 #ifdef KEY_DEBUGGING
 141         unsigned                magic;
 142 #define KEY_DEBUG_MAGIC         0x18273645u
 143 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 144 #endif
 145
 146         unsigned long           flags;          /* status flags (change with bitops) */
 147 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 148 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 149 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 150 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 151 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 152 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 153
 154         /* the description string
 155          * - this is used to match a key against search criteria
 156          * - this should be a printable string
 157          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 158          */
 159         char                    *description;
 160
 161         /* type specific data
 162          * - this is used by the keyring type to index the name
 163          */
 164         union {
 165                 struct list_head        link;
 166                 unsigned long           x[2];
 167                 void                    *p[2];
 168         } type_data;
 169
 170         /* key data
 171          * - this is used to hold the data actually used in cryptography or
 172          *   whatever
 173          */
 174         union {
 175                 unsigned long           value;
 176                 void                    *data;
 177                 struct keyring_list     *subscriptions;
 178         } payload;
 179 };
 180
 181 extern struct key *key_alloc(struct key_type *type,
 182                              const char *desc,
 183                              uid_t uid, gid_t gid,
 184                              struct task_struct *ctx,
 185                              key_perm_t perm,
 186                              unsigned long flags);
 187
 188
 189 #define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 190 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 191 #define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 192
 193 extern void key_revoke(struct key *key);
 194 extern void key_put(struct key *key);
 195
 196 static inline struct key *key_get(struct key *key)
 197 {
 198         if (key)
 199                 atomic_inc(&key->usage);
 200         return key;
 201 }
 202
 203 static inline void key_ref_put(key_ref_t key_ref)
 204 {
 205         key_put(key_ref_to_ptr(key_ref));
 206 }
 207
 208 extern struct key *request_key(struct key_type *type,
 209                                const char *description,
 210                                const char *callout_info);
 211
 212 extern struct key *request_key_with_auxdata(struct key_type *type,
 213                                             const char *description,
 214                                             const void *callout_info,
 215                                             size_t callout_len,
 216                                             void *aux);
 217
 218 extern struct key *request_key_async(struct key_type *type,
 219                                      const char *description,
 220                                      const void *callout_info,
 221                                      size_t callout_len);
 222
 223 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 224                                                   const char *description,
 225                                                   const void *callout_info,
 226                                                   size_t callout_len,
 227                                                   void *aux);
 228
 229 extern int wait_for_key_construction(struct key *key, bool intr);
 230
 231 extern int key_validate(struct key *key);
 232
 233 extern key_ref_t key_create_or_update(key_ref_t keyring,
 234                                       const char *type,
 235                                       const char *description,
 236                                       const void *payload,
 237                                       size_t plen,
 238                                       key_perm_t perm,
 239                                       unsigned long flags);
 240
 241 extern int key_update(key_ref_t key,
 242                       const void *payload,
 243                       size_t plen);
 244
 245 extern int key_link(struct key *keyring,
 246                     struct key *key);
 247
 248 extern int key_unlink(struct key *keyring,
 249                       struct key *key);
 250
 251 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 252                                  struct task_struct *ctx,
 253                                  unsigned long flags,
 254                                  struct key *dest);
 255
 256 extern int keyring_clear(struct key *keyring);
 257
 258 extern key_ref_t keyring_search(key_ref_t keyring,
 259                                 struct key_type *type,
 260                                 const char *description);
 261
 262 extern int keyring_add_key(struct key *keyring,
 263                            struct key *key);
 264
 265 extern struct key *key_lookup(key_serial_t id);
 266
 267 static inline key_serial_t key_serial(struct key *key)
 268 {
 269         return key ? key->serial : 0;
 270 }
 271
 272 #ifdef CONFIG_SYSCTL
 273 extern ctl_table key_sysctls[];
 274 #endif
 275
 276 /*
 277  * the userspace interface
 278  */
 279 extern void switch_uid_keyring(struct user_struct *new_user);
 280 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
 281 extern int copy_thread_group_keys(struct task_struct *tsk);
 282 extern void exit_keys(struct task_struct *tsk);
 283 extern void exit_thread_group_keys(struct signal_struct *tg);
 284 extern int suid_keys(struct task_struct *tsk);
 285 extern int exec_keys(struct task_struct *tsk);
 286 extern void key_fsuid_changed(struct task_struct *tsk);
 287 extern void key_fsgid_changed(struct task_struct *tsk);
 288 extern void key_init(void);
 289
 290 #define __install_session_keyring(tsk, keyring)                 \
 291 ({                                                              \
 292         struct key *old_session = tsk->signal->session_keyring; \
 293         tsk->signal->session_keyring = keyring;                 \
 294         old_session;                                            \
 295 })
 296
 297 #else /* CONFIG_KEYS */
 298
 299 #define key_validate(k)                 0
 300 #define key_serial(k)                   0
 301 #define key_get(k)                      ({ NULL; })
 302 #define key_revoke(k)                   do { } while(0)
 303 #define key_put(k)                      do { } while(0)
 304 #define key_ref_put(k)                  do { } while(0)
 305 #define make_key_ref(k, p)                      ({ NULL; })
 306 #define key_ref_to_ptr(k)               ({ NULL; })
 307 #define is_key_possessed(k)             0
 308 #define switch_uid_keyring(u)           do { } while(0)
 309 #define __install_session_keyring(t, k) ({ NULL; })
 310 #define copy_keys(f,t)                  0
 311 #define copy_thread_group_keys(t)       0
 312 #define exit_keys(t)                    do { } while(0)
 313 #define exit_thread_group_keys(tg)      do { } while(0)
 314 #define suid_keys(t)                    do { } while(0)
 315 #define exec_keys(t)                    do { } while(0)
 316 #define key_fsuid_changed(t)            do { } while(0)
 317 #define key_fsgid_changed(t)            do { } while(0)
 318 #define key_init()                      do { } while(0)
 319
 320 #endif /* CONFIG_KEYS */
 321 #endif /* __KERNEL__ */
 322 #endif /* _LINUX_KEY_H */