include/linux/key.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /* Authentication token and access key management
   3  *
   4  * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * See Documentation/security/keys/core.rst for information on keys/keyrings.
   8  */
   9
  10 #ifndef _LINUX_KEY_H
  11 #define _LINUX_KEY_H
  12
  13 #include <linux/types.h>
  14 #include <linux/list.h>
  15 #include <linux/rbtree.h>
  16 #include <linux/rcupdate.h>
  17 #include <linux/sysctl.h>
  18 #include <linux/rwsem.h>
  19 #include <linux/atomic.h>
  20 #include <linux/assoc_array.h>
  21 #include <linux/refcount.h>
  22 #include <linux/time64.h>
  23
  24 #ifdef __KERNEL__
  25 #include <linux/uidgid.h>
  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 struct cred;
  77
  78 struct key_type;
  79 struct key_owner;
  80 struct keyring_list;
  81 struct keyring_name;
  82
  83 struct keyring_index_key {
  84         struct key_type         *type;
  85         const char              *description;
  86         size_t                  desc_len;
  87 };
  88
  89 union key_payload {
  90         void __rcu              *rcu_data0;
  91         void                    *data[4];
  92 };
  93
  94 /*****************************************************************************/
  95 /*
  96  * key reference with possession attribute handling
  97  *
  98  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  99  * defined. This is because we abuse the bottom bit of the reference to carry a
 100  * flag to indicate whether the calling process possesses that key in one of
 101  * its keyrings.
 102  *
 103  * the key_ref_t has been made a separate type so that the compiler can reject
 104  * attempts to dereference it without proper conversion.
 105  *
 106  * the three functions are used to assemble and disassemble references
 107  */
 108 typedef struct __key_reference_with_attributes *key_ref_t;
 109
 110 static inline key_ref_t make_key_ref(const struct key *key,
 111                                      bool possession)
 112 {
 113         return (key_ref_t) ((unsigned long) key | possession);
 114 }
 115
 116 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 117 {
 118         return (struct key *) ((unsigned long) key_ref & ~1UL);
 119 }
 120
 121 static inline bool is_key_possessed(const key_ref_t key_ref)
 122 {
 123         return (unsigned long) key_ref & 1UL;
 124 }
 125
 126 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
 127                                         const struct key_type *type,
 128                                         const union key_payload *payload,
 129                                         struct key *restriction_key);
 130
 131 struct key_restriction {
 132         key_restrict_link_func_t check;
 133         struct key *key;
 134         struct key_type *keytype;
 135 };
 136
 137 enum key_state {
 138         KEY_IS_UNINSTANTIATED,
 139         KEY_IS_POSITIVE,                /* Positively instantiated */
 140 };
 141
 142 /*****************************************************************************/
 143 /*
 144  * authentication token / access credential / keyring
 145  * - types of key include:
 146  *   - keyrings
 147  *   - disk encryption IDs
 148  *   - Kerberos TGTs and tickets
 149  */
 150 struct key {
 151         refcount_t              usage;          /* number of references */
 152         key_serial_t            serial;         /* key serial number */
 153         union {
 154                 struct list_head graveyard_link;
 155                 struct rb_node  serial_node;
 156         };
 157         struct rw_semaphore     sem;            /* change vs change sem */
 158         struct key_user         *user;          /* owner of this key */
 159         void                    *security;      /* security data for this key */
 160         union {
 161                 time64_t        expiry;         /* time at which key expires (or 0) */
 162                 time64_t        revoked_at;     /* time at which key was revoked */
 163         };
 164         time64_t                last_used_at;   /* last time used for LRU keyring discard */
 165         kuid_t                  uid;
 166         kgid_t                  gid;
 167         key_perm_t              perm;           /* access permissions */
 168         unsigned short          quotalen;       /* length added to quota */
 169         unsigned short          datalen;        /* payload data length
 170                                                  * - may not match RCU dereferenced payload
 171                                                  * - payload should contain own length
 172                                                  */
 173         short                   state;          /* Key state (+) or rejection error (-) */
 174
 175 #ifdef KEY_DEBUGGING
 176         unsigned                magic;
 177 #define KEY_DEBUG_MAGIC         0x18273645u
 178 #endif
 179
 180         unsigned long           flags;          /* status flags (change with bitops) */
 181 #define KEY_FLAG_DEAD           0       /* set if key type has been deleted */
 182 #define KEY_FLAG_REVOKED        1       /* set if key had been revoked */
 183 #define KEY_FLAG_IN_QUOTA       2       /* set if key consumes quota */
 184 #define KEY_FLAG_USER_CONSTRUCT 3       /* set if key is being constructed in userspace */
 185 #define KEY_FLAG_ROOT_CAN_CLEAR 4       /* set if key can be cleared by root without permission */
 186 #define KEY_FLAG_INVALIDATED    5       /* set if key has been invalidated */
 187 #define KEY_FLAG_BUILTIN        6       /* set if key is built in to the kernel */
 188 #define KEY_FLAG_ROOT_CAN_INVAL 7       /* set if key can be invalidated by root without permission */
 189 #define KEY_FLAG_KEEP           8       /* set if key should not be removed */
 190 #define KEY_FLAG_UID_KEYRING    9       /* set if key is a user or user session keyring */
 191
 192         /* the key type and key description string
 193          * - the desc is used to match a key against search criteria
 194          * - it should be a printable string
 195          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 196          */
 197         union {
 198                 struct keyring_index_key index_key;
 199                 struct {
 200                         struct key_type *type;          /* type of key */
 201                         char            *description;
 202                 };
 203         };
 204
 205         /* key data
 206          * - this is used to hold the data actually used in cryptography or
 207          *   whatever
 208          */
 209         union {
 210                 union key_payload payload;
 211                 struct {
 212                         /* Keyring bits */
 213                         struct list_head name_link;
 214                         struct assoc_array keys;
 215                 };
 216         };
 217
 218         /* This is set on a keyring to restrict the addition of a link to a key
 219          * to it.  If this structure isn't provided then it is assumed that the
 220          * keyring is open to any addition.  It is ignored for non-keyring
 221          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 222          * or key_alloc().
 223          *
 224          * This is intended for use with rings of trusted keys whereby addition
 225          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 226          * overrides this, allowing the kernel to add extra keys without
 227          * restriction.
 228          */
 229         struct key_restriction *restrict_link;
 230 };
 231
 232 extern struct key *key_alloc(struct key_type *type,
 233                              const char *desc,
 234                              kuid_t uid, kgid_t gid,
 235                              const struct cred *cred,
 236                              key_perm_t perm,
 237                              unsigned long flags,
 238                              struct key_restriction *restrict_link);
 239
 240
 241 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 242 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 243 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 244 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 245 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 246 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
 247
 248 extern void key_revoke(struct key *key);
 249 extern void key_invalidate(struct key *key);
 250 extern void key_put(struct key *key);
 251
 252 static inline struct key *__key_get(struct key *key)
 253 {
 254         refcount_inc(&key->usage);
 255         return key;
 256 }
 257
 258 static inline struct key *key_get(struct key *key)
 259 {
 260         return key ? __key_get(key) : key;
 261 }
 262
 263 static inline void key_ref_put(key_ref_t key_ref)
 264 {
 265         key_put(key_ref_to_ptr(key_ref));
 266 }
 267
 268 extern struct key *request_key(struct key_type *type,
 269                                const char *description,
 270                                const char *callout_info);
 271
 272 extern struct key *request_key_with_auxdata(struct key_type *type,
 273                                             const char *description,
 274                                             const void *callout_info,
 275                                             size_t callout_len,
 276                                             void *aux);
 277
 278 extern struct key *request_key_async(struct key_type *type,
 279                                      const char *description,
 280                                      const void *callout_info,
 281                                      size_t callout_len);
 282
 283 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 284                                                   const char *description,
 285                                                   const void *callout_info,
 286                                                   size_t callout_len,
 287                                                   void *aux);
 288
 289 extern int wait_for_key_construction(struct key *key, bool intr);
 290
 291 extern int key_validate(const struct key *key);
 292
 293 extern key_ref_t key_create_or_update(key_ref_t keyring,
 294                                       const char *type,
 295                                       const char *description,
 296                                       const void *payload,
 297                                       size_t plen,
 298                                       key_perm_t perm,
 299                                       unsigned long flags);
 300
 301 extern int key_update(key_ref_t key,
 302                       const void *payload,
 303                       size_t plen);
 304
 305 extern int key_link(struct key *keyring,
 306                     struct key *key);
 307
 308 extern int key_unlink(struct key *keyring,
 309                       struct key *key);
 310
 311 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 312                                  const struct cred *cred,
 313                                  key_perm_t perm,
 314                                  unsigned long flags,
 315                                  struct key_restriction *restrict_link,
 316                                  struct key *dest);
 317
 318 extern int restrict_link_reject(struct key *keyring,
 319                                 const struct key_type *type,
 320                                 const union key_payload *payload,
 321                                 struct key *restriction_key);
 322
 323 extern int keyring_clear(struct key *keyring);
 324
 325 extern key_ref_t keyring_search(key_ref_t keyring,
 326                                 struct key_type *type,
 327                                 const char *description);
 328
 329 extern int keyring_add_key(struct key *keyring,
 330                            struct key *key);
 331
 332 extern int keyring_restrict(key_ref_t keyring, const char *type,
 333                             const char *restriction);
 334
 335 extern struct key *key_lookup(key_serial_t id);
 336
 337 static inline key_serial_t key_serial(const struct key *key)
 338 {
 339         return key ? key->serial : 0;
 340 }
 341
 342 extern void key_set_timeout(struct key *, unsigned);
 343
 344 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
 345                                  key_perm_t perm);
 346
 347 /*
 348  * The permissions required on a key that we're looking up.
 349  */
 350 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 351 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 352 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 353 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 354 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 355 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 356 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 357
 358 static inline short key_read_state(const struct key *key)
 359 {
 360         /* Barrier versus mark_key_instantiated(). */
 361         return smp_load_acquire(&key->state);
 362 }
 363
 364 /**
 365  * key_is_positive - Determine if a key has been positively instantiated
 366  * @key: The key to check.
 367  *
 368  * Return true if the specified key has been positively instantiated, false
 369  * otherwise.
 370  */
 371 static inline bool key_is_positive(const struct key *key)
 372 {
 373         return key_read_state(key) == KEY_IS_POSITIVE;
 374 }
 375
 376 static inline bool key_is_negative(const struct key *key)
 377 {
 378         return key_read_state(key) < 0;
 379 }
 380
 381 #define dereference_key_rcu(KEY)                                        \
 382         (rcu_dereference((KEY)->payload.rcu_data0))
 383
 384 #define dereference_key_locked(KEY)                                     \
 385         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 386                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 387
 388 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 389 do {                                                                    \
 390         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 391 } while (0)
 392
 393 #ifdef CONFIG_SYSCTL
 394 extern struct ctl_table key_sysctls[];
 395 #endif
 396 /*
 397  * the userspace interface
 398  */
 399 extern int install_thread_keyring_to_cred(struct cred *cred);
 400 extern void key_fsuid_changed(struct task_struct *tsk);
 401 extern void key_fsgid_changed(struct task_struct *tsk);
 402 extern void key_init(void);
 403
 404 #else /* CONFIG_KEYS */
 405
 406 #define key_validate(k)                 0
 407 #define key_serial(k)                   0
 408 #define key_get(k)                      ({ NULL; })
 409 #define key_revoke(k)                   do { } while(0)
 410 #define key_invalidate(k)               do { } while(0)
 411 #define key_put(k)                      do { } while(0)
 412 #define key_ref_put(k)                  do { } while(0)
 413 #define make_key_ref(k, p)              NULL
 414 #define key_ref_to_ptr(k)               NULL
 415 #define is_key_possessed(k)             0
 416 #define key_fsuid_changed(t)            do { } while(0)
 417 #define key_fsgid_changed(t)            do { } while(0)
 418 #define key_init()                      do { } while(0)
 419
 420 #endif /* CONFIG_KEYS */
 421 #endif /* __KERNEL__ */
 422 #endif /* _LINUX_KEY_H */