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Linux/include/linux/key.h

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  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 struct net;
 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 key_tag;
 82 struct keyring_list;
 83 struct keyring_name;
 84 
 85 struct key_tag {
 86         struct rcu_head         rcu;
 87         refcount_t              usage;
 88         bool                    removed;        /* T when subject removed */
 89 };
 90 
 91 struct keyring_index_key {
 92         /* [!] If this structure is altered, the union in struct key must change too! */
 93         unsigned long           hash;                   /* Hash value */
 94         union {
 95                 struct {
 96 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
 97                         u16     desc_len;
 98                         char    desc[sizeof(long) - 2]; /* First few chars of description */
 99 #else
100                         char    desc[sizeof(long) - 2]; /* First few chars of description */
101                         u16     desc_len;
102 #endif
103                 };
104                 unsigned long x;
105         };
106         struct key_type         *type;
107         struct key_tag          *domain_tag;    /* Domain of operation */
108         const char              *description;
109 };
110 
111 union key_payload {
112         void __rcu              *rcu_data0;
113         void                    *data[4];
114 };
115 
116 /*****************************************************************************/
117 /*
118  * key reference with possession attribute handling
119  *
120  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
121  * defined. This is because we abuse the bottom bit of the reference to carry a
122  * flag to indicate whether the calling process possesses that key in one of
123  * its keyrings.
124  *
125  * the key_ref_t has been made a separate type so that the compiler can reject
126  * attempts to dereference it without proper conversion.
127  *
128  * the three functions are used to assemble and disassemble references
129  */
130 typedef struct __key_reference_with_attributes *key_ref_t;
131 
132 static inline key_ref_t make_key_ref(const struct key *key,
133                                      bool possession)
134 {
135         return (key_ref_t) ((unsigned long) key | possession);
136 }
137 
138 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
139 {
140         return (struct key *) ((unsigned long) key_ref & ~1UL);
141 }
142 
143 static inline bool is_key_possessed(const key_ref_t key_ref)
144 {
145         return (unsigned long) key_ref & 1UL;
146 }
147 
148 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
149                                         const struct key_type *type,
150                                         const union key_payload *payload,
151                                         struct key *restriction_key);
152 
153 struct key_restriction {
154         key_restrict_link_func_t check;
155         struct key *key;
156         struct key_type *keytype;
157 };
158 
159 enum key_state {
160         KEY_IS_UNINSTANTIATED,
161         KEY_IS_POSITIVE,                /* Positively instantiated */
162 };
163 
164 /*****************************************************************************/
165 /*
166  * authentication token / access credential / keyring
167  * - types of key include:
168  *   - keyrings
169  *   - disk encryption IDs
170  *   - Kerberos TGTs and tickets
171  */
172 struct key {
173         refcount_t              usage;          /* number of references */
174         key_serial_t            serial;         /* key serial number */
175         union {
176                 struct list_head graveyard_link;
177                 struct rb_node  serial_node;
178         };
179         struct rw_semaphore     sem;            /* change vs change sem */
180         struct key_user         *user;          /* owner of this key */
181         void                    *security;      /* security data for this key */
182         union {
183                 time64_t        expiry;         /* time at which key expires (or 0) */
184                 time64_t        revoked_at;     /* time at which key was revoked */
185         };
186         time64_t                last_used_at;   /* last time used for LRU keyring discard */
187         kuid_t                  uid;
188         kgid_t                  gid;
189         key_perm_t              perm;           /* access permissions */
190         unsigned short          quotalen;       /* length added to quota */
191         unsigned short          datalen;        /* payload data length
192                                                  * - may not match RCU dereferenced payload
193                                                  * - payload should contain own length
194                                                  */
195         short                   state;          /* Key state (+) or rejection error (-) */
196 
197 #ifdef KEY_DEBUGGING
198         unsigned                magic;
199 #define KEY_DEBUG_MAGIC         0x18273645u
200 #endif
201 
202         unsigned long           flags;          /* status flags (change with bitops) */
203 #define KEY_FLAG_DEAD           0       /* set if key type has been deleted */
204 #define KEY_FLAG_REVOKED        1       /* set if key had been revoked */
205 #define KEY_FLAG_IN_QUOTA       2       /* set if key consumes quota */
206 #define KEY_FLAG_USER_CONSTRUCT 3       /* set if key is being constructed in userspace */
207 #define KEY_FLAG_ROOT_CAN_CLEAR 4       /* set if key can be cleared by root without permission */
208 #define KEY_FLAG_INVALIDATED    5       /* set if key has been invalidated */
209 #define KEY_FLAG_BUILTIN        6       /* set if key is built in to the kernel */
210 #define KEY_FLAG_ROOT_CAN_INVAL 7       /* set if key can be invalidated by root without permission */
211 #define KEY_FLAG_KEEP           8       /* set if key should not be removed */
212 #define KEY_FLAG_UID_KEYRING    9       /* set if key is a user or user session keyring */
213 
214         /* the key type and key description string
215          * - the desc is used to match a key against search criteria
216          * - it should be a printable string
217          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
218          */
219         union {
220                 struct keyring_index_key index_key;
221                 struct {
222                         unsigned long   hash;
223                         unsigned long   len_desc;
224                         struct key_type *type;          /* type of key */
225                         struct key_tag  *domain_tag;    /* Domain of operation */
226                         char            *description;
227                 };
228         };
229 
230         /* key data
231          * - this is used to hold the data actually used in cryptography or
232          *   whatever
233          */
234         union {
235                 union key_payload payload;
236                 struct {
237                         /* Keyring bits */
238                         struct list_head name_link;
239                         struct assoc_array keys;
240                 };
241         };
242 
243         /* This is set on a keyring to restrict the addition of a link to a key
244          * to it.  If this structure isn't provided then it is assumed that the
245          * keyring is open to any addition.  It is ignored for non-keyring
246          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
247          * or key_alloc().
248          *
249          * This is intended for use with rings of trusted keys whereby addition
250          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
251          * overrides this, allowing the kernel to add extra keys without
252          * restriction.
253          */
254         struct key_restriction *restrict_link;
255 };
256 
257 extern struct key *key_alloc(struct key_type *type,
258                              const char *desc,
259                              kuid_t uid, kgid_t gid,
260                              const struct cred *cred,
261                              key_perm_t perm,
262                              unsigned long flags,
263                              struct key_restriction *restrict_link);
264 
265 
266 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
267 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
268 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
269 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
270 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
271 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
272 
273 extern void key_revoke(struct key *key);
274 extern void key_invalidate(struct key *key);
275 extern void key_put(struct key *key);
276 extern bool key_put_tag(struct key_tag *tag);
277 extern void key_remove_domain(struct key_tag *domain_tag);
278 
279 static inline struct key *__key_get(struct key *key)
280 {
281         refcount_inc(&key->usage);
282         return key;
283 }
284 
285 static inline struct key *key_get(struct key *key)
286 {
287         return key ? __key_get(key) : key;
288 }
289 
290 static inline void key_ref_put(key_ref_t key_ref)
291 {
292         key_put(key_ref_to_ptr(key_ref));
293 }
294 
295 extern struct key *request_key_tag(struct key_type *type,
296                                    const char *description,
297                                    struct key_tag *domain_tag,
298                                    const char *callout_info);
299 
300 extern struct key *request_key_rcu(struct key_type *type,
301                                    const char *description,
302                                    struct key_tag *domain_tag);
303 
304 extern struct key *request_key_with_auxdata(struct key_type *type,
305                                             const char *description,
306                                             struct key_tag *domain_tag,
307                                             const void *callout_info,
308                                             size_t callout_len,
309                                             void *aux);
310 
311 /**
312  * request_key - Request a key and wait for construction
313  * @type: Type of key.
314  * @description: The searchable description of the key.
315  * @callout_info: The data to pass to the instantiation upcall (or NULL).
316  *
317  * As for request_key_tag(), but with the default global domain tag.
318  */
319 static inline struct key *request_key(struct key_type *type,
320                                       const char *description,
321                                       const char *callout_info)
322 {
323         return request_key_tag(type, description, NULL, callout_info);
324 }
325 
326 #ifdef CONFIG_NET
327 /**
328  * request_key_net - Request a key for a net namespace and wait for construction
329  * @type: Type of key.
330  * @description: The searchable description of the key.
331  * @net: The network namespace that is the key's domain of operation.
332  * @callout_info: The data to pass to the instantiation upcall (or NULL).
333  *
334  * As for request_key() except that it does not add the returned key to a
335  * keyring if found, new keys are always allocated in the user's quota, the
336  * callout_info must be a NUL-terminated string and no auxiliary data can be
337  * passed.  Only keys that operate the specified network namespace are used.
338  *
339  * Furthermore, it then works as wait_for_key_construction() to wait for the
340  * completion of keys undergoing construction with a non-interruptible wait.
341  */
342 #define request_key_net(type, description, net, callout_info) \
343         request_key_tag(type, description, net->key_domain, callout_info);
344 
345 /**
346  * request_key_net_rcu - Request a key for a net namespace under RCU conditions
347  * @type: Type of key.
348  * @description: The searchable description of the key.
349  * @net: The network namespace that is the key's domain of operation.
350  *
351  * As for request_key_rcu() except that only keys that operate the specified
352  * network namespace are used.
353  */
354 #define request_key_net_rcu(type, description, net) \
355         request_key_rcu(type, description, net->key_domain);
356 #endif /* CONFIG_NET */
357 
358 extern int wait_for_key_construction(struct key *key, bool intr);
359 
360 extern int key_validate(const struct key *key);
361 
362 extern key_ref_t key_create_or_update(key_ref_t keyring,
363                                       const char *type,
364                                       const char *description,
365                                       const void *payload,
366                                       size_t plen,
367                                       key_perm_t perm,
368                                       unsigned long flags);
369 
370 extern int key_update(key_ref_t key,
371                       const void *payload,
372                       size_t plen);
373 
374 extern int key_link(struct key *keyring,
375                     struct key *key);
376 
377 extern int key_move(struct key *key,
378                     struct key *from_keyring,
379                     struct key *to_keyring,
380                     unsigned int flags);
381 
382 extern int key_unlink(struct key *keyring,
383                       struct key *key);
384 
385 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
386                                  const struct cred *cred,
387                                  key_perm_t perm,
388                                  unsigned long flags,
389                                  struct key_restriction *restrict_link,
390                                  struct key *dest);
391 
392 extern int restrict_link_reject(struct key *keyring,
393                                 const struct key_type *type,
394                                 const union key_payload *payload,
395                                 struct key *restriction_key);
396 
397 extern int keyring_clear(struct key *keyring);
398 
399 extern key_ref_t keyring_search(key_ref_t keyring,
400                                 struct key_type *type,
401                                 const char *description,
402                                 bool recurse);
403 
404 extern int keyring_add_key(struct key *keyring,
405                            struct key *key);
406 
407 extern int keyring_restrict(key_ref_t keyring, const char *type,
408                             const char *restriction);
409 
410 extern struct key *key_lookup(key_serial_t id);
411 
412 static inline key_serial_t key_serial(const struct key *key)
413 {
414         return key ? key->serial : 0;
415 }
416 
417 extern void key_set_timeout(struct key *, unsigned);
418 
419 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
420                                  key_perm_t perm);
421 extern void key_free_user_ns(struct user_namespace *);
422 
423 /*
424  * The permissions required on a key that we're looking up.
425  */
426 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
427 #define KEY_NEED_READ   0x02    /* Require permission to read content */
428 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
429 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
430 #define KEY_NEED_LINK   0x10    /* Require permission to link */
431 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
432 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
433 
434 static inline short key_read_state(const struct key *key)
435 {
436         /* Barrier versus mark_key_instantiated(). */
437         return smp_load_acquire(&key->state);
438 }
439 
440 /**
441  * key_is_positive - Determine if a key has been positively instantiated
442  * @key: The key to check.
443  *
444  * Return true if the specified key has been positively instantiated, false
445  * otherwise.
446  */
447 static inline bool key_is_positive(const struct key *key)
448 {
449         return key_read_state(key) == KEY_IS_POSITIVE;
450 }
451 
452 static inline bool key_is_negative(const struct key *key)
453 {
454         return key_read_state(key) < 0;
455 }
456 
457 #define dereference_key_rcu(KEY)                                        \
458         (rcu_dereference((KEY)->payload.rcu_data0))
459 
460 #define dereference_key_locked(KEY)                                     \
461         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
462                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
463 
464 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
465 do {                                                                    \
466         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
467 } while (0)
468 
469 #ifdef CONFIG_SYSCTL
470 extern struct ctl_table key_sysctls[];
471 #endif
472 /*
473  * the userspace interface
474  */
475 extern int install_thread_keyring_to_cred(struct cred *cred);
476 extern void key_fsuid_changed(struct cred *new_cred);
477 extern void key_fsgid_changed(struct cred *new_cred);
478 extern void key_init(void);
479 
480 #else /* CONFIG_KEYS */
481 
482 #define key_validate(k)                 0
483 #define key_serial(k)                   0
484 #define key_get(k)                      ({ NULL; })
485 #define key_revoke(k)                   do { } while(0)
486 #define key_invalidate(k)               do { } while(0)
487 #define key_put(k)                      do { } while(0)
488 #define key_ref_put(k)                  do { } while(0)
489 #define make_key_ref(k, p)              NULL
490 #define key_ref_to_ptr(k)               NULL
491 #define is_key_possessed(k)             0
492 #define key_fsuid_changed(c)            do { } while(0)
493 #define key_fsgid_changed(c)            do { } while(0)
494 #define key_init()                      do { } while(0)
495 #define key_free_user_ns(ns)            do { } while(0)
496 #define key_remove_domain(d)            do { } while(0)
497 
498 #endif /* CONFIG_KEYS */
499 #endif /* __KERNEL__ */
500 #endif /* _LINUX_KEY_H */
501 

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