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/core.rst 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 #include <linux/refcount.h>
  27 #include <linux/time64.h>
  28
  29 #ifdef __KERNEL__
  30 #include <linux/uidgid.h>
  31
  32 /* key handle serial number */
  33 typedef int32_t key_serial_t;
  34
  35 /* key handle permissions mask */
  36 typedef uint32_t key_perm_t;
  37
  38 struct key;
  39
  40 #ifdef CONFIG_KEYS
  41
  42 #undef KEY_DEBUGGING
  43
  44 #define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  45 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  46 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  47 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  48 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  49 #define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  50 #define KEY_POS_ALL     0x3f000000
  51
  52 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  53 #define KEY_USR_READ    0x00020000
  54 #define KEY_USR_WRITE   0x00040000
  55 #define KEY_USR_SEARCH  0x00080000
  56 #define KEY_USR_LINK    0x00100000
  57 #define KEY_USR_SETATTR 0x00200000
  58 #define KEY_USR_ALL     0x003f0000
  59
  60 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  61 #define KEY_GRP_READ    0x00000200
  62 #define KEY_GRP_WRITE   0x00000400
  63 #define KEY_GRP_SEARCH  0x00000800
  64 #define KEY_GRP_LINK    0x00001000
  65 #define KEY_GRP_SETATTR 0x00002000
  66 #define KEY_GRP_ALL     0x00003f00
  67
  68 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  69 #define KEY_OTH_READ    0x00000002
  70 #define KEY_OTH_WRITE   0x00000004
  71 #define KEY_OTH_SEARCH  0x00000008
  72 #define KEY_OTH_LINK    0x00000010
  73 #define KEY_OTH_SETATTR 0x00000020
  74 #define KEY_OTH_ALL     0x0000003f
  75
  76 #define KEY_PERM_UNDEF  0xffffffff
  77
  78 struct seq_file;
  79 struct user_struct;
  80 struct signal_struct;
  81 struct cred;
  82
  83 struct key_type;
  84 struct key_owner;
  85 struct keyring_list;
  86 struct keyring_name;
  87
  88 struct keyring_index_key {
  89         struct key_type         *type;
  90         const char              *description;
  91         size_t                  desc_len;
  92 };
  93
  94 union key_payload {
  95         void __rcu              *rcu_data0;
  96         void                    *data[4];
  97 };
  98
  99 /*****************************************************************************/
 100 /*
 101  * key reference with possession attribute handling
 102  *
 103  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 104  * defined. This is because we abuse the bottom bit of the reference to carry a
 105  * flag to indicate whether the calling process possesses that key in one of
 106  * its keyrings.
 107  *
 108  * the key_ref_t has been made a separate type so that the compiler can reject
 109  * attempts to dereference it without proper conversion.
 110  *
 111  * the three functions are used to assemble and disassemble references
 112  */
 113 typedef struct __key_reference_with_attributes *key_ref_t;
 114
 115 static inline key_ref_t make_key_ref(const struct key *key,
 116                                      bool possession)
 117 {
 118         return (key_ref_t) ((unsigned long) key | possession);
 119 }
 120
 121 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 122 {
 123         return (struct key *) ((unsigned long) key_ref & ~1UL);
 124 }
 125
 126 static inline bool is_key_possessed(const key_ref_t key_ref)
 127 {
 128         return (unsigned long) key_ref & 1UL;
 129 }
 130
 131 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
 132                                         const struct key_type *type,
 133                                         const union key_payload *payload,
 134                                         struct key *restriction_key);
 135
 136 struct key_restriction {
 137         key_restrict_link_func_t check;
 138         struct key *key;
 139         struct key_type *keytype;
 140 };
 141
 142 enum key_state {
 143         KEY_IS_UNINSTANTIATED,
 144         KEY_IS_POSITIVE,                /* Positively instantiated */
 145 };
 146
 147 /*****************************************************************************/
 148 /*
 149  * authentication token / access credential / keyring
 150  * - types of key include:
 151  *   - keyrings
 152  *   - disk encryption IDs
 153  *   - Kerberos TGTs and tickets
 154  */
 155 struct key {
 156         refcount_t              usage;          /* number of references */
 157         key_serial_t            serial;         /* key serial number */
 158         union {
 159                 struct list_head graveyard_link;
 160                 struct rb_node  serial_node;
 161         };
 162         struct rw_semaphore     sem;            /* change vs change sem */
 163         struct key_user         *user;          /* owner of this key */
 164         void                    *security;      /* security data for this key */
 165         union {
 166                 time64_t        expiry;         /* time at which key expires (or 0) */
 167                 time64_t        revoked_at;     /* time at which key was revoked */
 168         };
 169         time64_t                last_used_at;   /* last time used for LRU keyring discard */
 170         kuid_t                  uid;
 171         kgid_t                  gid;
 172         key_perm_t              perm;           /* access permissions */
 173         unsigned short          quotalen;       /* length added to quota */
 174         unsigned short          datalen;        /* payload data length
 175                                                  * - may not match RCU dereferenced payload
 176                                                  * - payload should contain own length
 177                                                  */
 178         short                   state;          /* Key state (+) or rejection error (-) */
 179
 180 #ifdef KEY_DEBUGGING
 181         unsigned                magic;
 182 #define KEY_DEBUG_MAGIC         0x18273645u
 183 #endif
 184
 185         unsigned long           flags;          /* status flags (change with bitops) */
 186 #define KEY_FLAG_DEAD           0       /* set if key type has been deleted */
 187 #define KEY_FLAG_REVOKED        1       /* set if key had been revoked */
 188 #define KEY_FLAG_IN_QUOTA       2       /* set if key consumes quota */
 189 #define KEY_FLAG_USER_CONSTRUCT 3       /* set if key is being constructed in userspace */
 190 #define KEY_FLAG_ROOT_CAN_CLEAR 4       /* set if key can be cleared by root without permission */
 191 #define KEY_FLAG_INVALIDATED    5       /* set if key has been invalidated */
 192 #define KEY_FLAG_BUILTIN        6       /* set if key is built in to the kernel */
 193 #define KEY_FLAG_ROOT_CAN_INVAL 7       /* set if key can be invalidated by root without permission */
 194 #define KEY_FLAG_KEEP           8       /* set if key should not be removed */
 195 #define KEY_FLAG_UID_KEYRING    9       /* set if key is a user or user session keyring */
 196
 197         /* the key type and key description string
 198          * - the desc is used to match a key against search criteria
 199          * - it should be a printable string
 200          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 201          */
 202         union {
 203                 struct keyring_index_key index_key;
 204                 struct {
 205                         struct key_type *type;          /* type of key */
 206                         char            *description;
 207                 };
 208         };
 209
 210         /* key data
 211          * - this is used to hold the data actually used in cryptography or
 212          *   whatever
 213          */
 214         union {
 215                 union key_payload payload;
 216                 struct {
 217                         /* Keyring bits */
 218                         struct list_head name_link;
 219                         struct assoc_array keys;
 220                 };
 221         };
 222
 223         /* This is set on a keyring to restrict the addition of a link to a key
 224          * to it.  If this structure isn't provided then it is assumed that the
 225          * keyring is open to any addition.  It is ignored for non-keyring
 226          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 227          * or key_alloc().
 228          *
 229          * This is intended for use with rings of trusted keys whereby addition
 230          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 231          * overrides this, allowing the kernel to add extra keys without
 232          * restriction.
 233          */
 234         struct key_restriction *restrict_link;
 235 };
 236
 237 extern struct key *key_alloc(struct key_type *type,
 238                              const char *desc,
 239                              kuid_t uid, kgid_t gid,
 240                              const struct cred *cred,
 241                              key_perm_t perm,
 242                              unsigned long flags,
 243                              struct key_restriction *restrict_link);
 244
 245
 246 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 247 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 248 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 249 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 250 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 251 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
 252
 253 extern void key_revoke(struct key *key);
 254 extern void key_invalidate(struct key *key);
 255 extern void key_put(struct key *key);
 256
 257 static inline struct key *__key_get(struct key *key)
 258 {
 259         refcount_inc(&key->usage);
 260         return key;
 261 }
 262
 263 static inline struct key *key_get(struct key *key)
 264 {
 265         return key ? __key_get(key) : key;
 266 }
 267
 268 static inline void key_ref_put(key_ref_t key_ref)
 269 {
 270         key_put(key_ref_to_ptr(key_ref));
 271 }
 272
 273 extern struct key *request_key(struct key_type *type,
 274                                const char *description,
 275                                const char *callout_info);
 276
 277 extern struct key *request_key_with_auxdata(struct key_type *type,
 278                                             const char *description,
 279                                             const void *callout_info,
 280                                             size_t callout_len,
 281                                             void *aux);
 282
 283 extern struct key *request_key_async(struct key_type *type,
 284                                      const char *description,
 285                                      const void *callout_info,
 286                                      size_t callout_len);
 287
 288 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 289                                                   const char *description,
 290                                                   const void *callout_info,
 291                                                   size_t callout_len,
 292                                                   void *aux);
 293
 294 extern int wait_for_key_construction(struct key *key, bool intr);
 295
 296 extern int key_validate(const 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                                       key_perm_t perm,
 304                                       unsigned long flags);
 305
 306 extern int key_update(key_ref_t key,
 307                       const void *payload,
 308                       size_t plen);
 309
 310 extern int key_link(struct key *keyring,
 311                     struct key *key);
 312
 313 extern int key_unlink(struct key *keyring,
 314                       struct key *key);
 315
 316 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 317                                  const struct cred *cred,
 318                                  key_perm_t perm,
 319                                  unsigned long flags,
 320                                  struct key_restriction *restrict_link,
 321                                  struct key *dest);
 322
 323 extern int restrict_link_reject(struct key *keyring,
 324                                 const struct key_type *type,
 325                                 const union key_payload *payload,
 326                                 struct key *restriction_key);
 327
 328 extern int keyring_clear(struct key *keyring);
 329
 330 extern key_ref_t keyring_search(key_ref_t keyring,
 331                                 struct key_type *type,
 332                                 const char *description);
 333
 334 extern int keyring_add_key(struct key *keyring,
 335                            struct key *key);
 336
 337 extern int keyring_restrict(key_ref_t keyring, const char *type,
 338                             const char *restriction);
 339
 340 extern struct key *key_lookup(key_serial_t id);
 341
 342 static inline key_serial_t key_serial(const struct key *key)
 343 {
 344         return key ? key->serial : 0;
 345 }
 346
 347 extern void key_set_timeout(struct key *, unsigned);
 348
 349 /*
 350  * The permissions required on a key that we're looking up.
 351  */
 352 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 353 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 354 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 355 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 356 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 357 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 358 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 359
 360 static inline short key_read_state(const struct key *key)
 361 {
 362         /* Barrier versus mark_key_instantiated(). */
 363         return smp_load_acquire(&key->state);
 364 }
 365
 366 /**
 367  * key_is_positive - Determine if a key has been positively instantiated
 368  * @key: The key to check.
 369  *
 370  * Return true if the specified key has been positively instantiated, false
 371  * otherwise.
 372  */
 373 static inline bool key_is_positive(const struct key *key)
 374 {
 375         return key_read_state(key) == KEY_IS_POSITIVE;
 376 }
 377
 378 static inline bool key_is_negative(const struct key *key)
 379 {
 380         return key_read_state(key) < 0;
 381 }
 382
 383 #define dereference_key_rcu(KEY)                                        \
 384         (rcu_dereference((KEY)->payload.rcu_data0))
 385
 386 #define dereference_key_locked(KEY)                                     \
 387         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 388                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 389
 390 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 391 do {                                                                    \
 392         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 393 } while (0)
 394
 395 #ifdef CONFIG_SYSCTL
 396 extern struct ctl_table key_sysctls[];
 397 #endif
 398 /*
 399  * the userspace interface
 400  */
 401 extern int install_thread_keyring_to_cred(struct cred *cred);
 402 extern void key_fsuid_changed(struct task_struct *tsk);
 403 extern void key_fsgid_changed(struct task_struct *tsk);
 404 extern void key_init(void);
 405
 406 #else /* CONFIG_KEYS */
 407
 408 #define key_validate(k)                 0
 409 #define key_serial(k)                   0
 410 #define key_get(k)                      ({ NULL; })
 411 #define key_revoke(k)                   do { } while(0)
 412 #define key_invalidate(k)               do { } while(0)
 413 #define key_put(k)                      do { } while(0)
 414 #define key_ref_put(k)                  do { } while(0)
 415 #define make_key_ref(k, p)              NULL
 416 #define key_ref_to_ptr(k)               NULL
 417 #define is_key_possessed(k)             0
 418 #define key_fsuid_changed(t)            do { } while(0)
 419 #define key_fsgid_changed(t)            do { } while(0)
 420 #define key_init()                      do { } while(0)
 421
 422 #endif /* CONFIG_KEYS */
 423 #endif /* __KERNEL__ */
 424 #endif /* _LINUX_KEY_H */