1KEYCTL(2) Linux Key Management Calls KEYCTL(2)
2
6 keyctl - manipulate the kernel's key management facility
7
9 #include <sys/types.h>
10 #include <keyutils.h>
11 long keyctl(int operation, ...)
13 /* For direct call via syscall(2): */
15 #include <asm/unistd.h>
16 #include <linux/keyctl.h>
17 #include <unistd.h>
18 long syscall(__NR_keyctl, int operation, __kernel_ulong_t arg2,
20 __kernel_ulong_t arg3, __kernel_ulong_t arg4,
21 __kernel_ulong_t arg5);
22 No glibc wrapper is provided for this system call; see NOTES.
24
26 keyctl() allows user-space programs to perform key manipulation.
27 The operation performed by keyctl() is determined by the value of the
29 operation argument. Each of these operations is wrapped by the
30 libkeyutils library (provided by the keyutils package) into individual
31 functions (noted below) to permit the compiler to check types.
32 The permitted values for operation are:
34 KEYCTL_GET_KEYRING_ID (since Linux 2.6.10)
36 Map a special key ID to a real key ID for this process.
37 This operation looks up the special key whose ID is provided in
39 arg2 (cast to key_serial_t). If the special key is found, the
40 ID of the corresponding real key is returned as the function
41 result. The following values may be specified in arg2:
42 KEY_SPEC_THREAD_KEYRING
44 This specifies the calling thread's thread-specific
45 keyring. See thread-keyring(7).
46 KEY_SPEC_PROCESS_KEYRING
48 This specifies the caller's process-specific keyring.
49 See process-keyring(7).
50 KEY_SPEC_SESSION_KEYRING
52 This specifies the caller's session-specific keyring.
53 See session-keyring(7).
54 KEY_SPEC_USER_KEYRING
56 This specifies the caller's UID-specific keyring. See
57 user-keyring(7).
58 KEY_SPEC_USER_SESSION_KEYRING
60 This specifies the caller's UID-session keyring. See
61 user-session-keyring(7).
62 KEY_SPEC_REQKEY_AUTH_KEY (since Linux 2.6.16)
64 This specifies the authorization key created by
65 request_key(2) and passed to the process it spawns to
66 generate a key. This key is available only in a request-
67 key(8)-style program that was passed an authorization key
68 by the kernel and ceases to be available once the
69 requested key has been instantiated; see request_key(2).
70 KEY_SPEC_REQUESTOR_KEYRING (since Linux 2.6.29)
72 This specifies the key ID for the request_key(2) destina‐
73 tion keyring. This keyring is available only in a
74 request-key(8)-style program that was passed an autho‐
75 rization key by the kernel and ceases to be available
76 once the requested key has been instantiated; see
77 request_key(2).
78 The behavior if the key specified in arg2 does not exist depends
80 on the value of arg3 (cast to int). If arg3 contains a nonzero
81 value, then—if it is appropriate to do so (e.g., when looking up
82 the user, user-session, or session key)—a new key is created and
83 its real key ID returned as the function result. Otherwise, the
84 operation fails with the error ENOKEY.
85 If a valid key ID is specified in arg2, and the key exists, then
87 this operation simply returns the key ID. If the key does not
88 exist, the call fails with error ENOKEY.
89 The caller must have search permission on a keyring in order for
91 it to be found.
92 The arguments arg4 and arg5 are ignored.
94 This operation is exposed by libkeyutils via the function
96 keyctl_get_keyring_ID(3).
97 KEYCTL_JOIN_SESSION_KEYRING (since Linux 2.6.10)
99 Replace the session keyring this process subscribes to with a
100 new session keyring.
101 If arg2 is NULL, an anonymous keyring with the description
103 "_ses" is created and the process is subscribed to that keyring
104 as its session keyring, displacing the previous session keyring.
105 Otherwise, arg2 (cast to char *) is treated as the description
107 (name) of a keyring, and the behavior is as follows:
108 * If a keyring with a matching description exists, the process
110 will attempt to subscribe to that keyring as its session
111 keyring if possible; if that is not possible, an error is
112 returned. In order to subscribe to the keyring, the caller
113 must have search permission on the keyring.
114 * If a keyring with a matching description does not exist, then
116 a new keyring with the specified description is created, and
117 the process is subscribed to that keyring as its session
118 keyring.
119 The arguments arg3, arg4, and arg5 are ignored.
121 This operation is exposed by libkeyutils via the function
123 keyctl_join_session_keyring(3).
124 KEYCTL_UPDATE (since Linux 2.6.10)
126 Update a key's data payload.
127 The arg2 argument (cast to key_serial_t) specifies the ID of the
129 key to be updated. The arg3 argument (cast to void *) points to
130 the new payload and arg4 (cast to size_t) contains the new pay‐
131 load size in bytes.
132 The caller must have write permission on the key specified and
134 the key type must support updating.
135 A negatively instantiated key (see the description of
137 KEYCTL_REJECT) can be positively instantiated with this opera‐
138 tion.
139 The arg5 argument is ignored.
141 This operation is exposed by libkeyutils via the function
143 keyctl_update(3).
144 KEYCTL_REVOKE (since Linux 2.6.10)
146 Revoke the key with the ID provided in arg2 (cast to
147 key_serial_t). The key is scheduled for garbage collection; it
148 will no longer be findable, and will be unavailable for further
149 operations. Further attempts to use the key will fail with the
150 error EKEYREVOKED.
151 The caller must have write or setattr permission on the key.
153 The arguments arg3, arg4, and arg5 are ignored.
155 This operation is exposed by libkeyutils via the function
157 keyctl_revoke(3).
158 KEYCTL_CHOWN (since Linux 2.6.10)
160 Change the ownership (user and group ID) of a key.
161 The arg2 argument (cast to key_serial_t) contains the key ID.
163 The arg3 argument (cast to uid_t) contains the new user ID (or
164 -1 in case the user ID shouldn't be changed). The arg4 argument
165 (cast to gid_t) contains the new group ID (or -1 in case the
166 group ID shouldn't be changed).
167 The key must grant the caller setattr permission.
169 For the UID to be changed, or for the GID to be changed to a
171 group the caller is not a member of, the caller must have the
172 CAP_SYS_ADMIN capability (see capabilities(7)).
173 If the UID is to be changed, the new user must have sufficient
175 quota to accept the key. The quota deduction will be removed
176 from the old user to the new user should the UID be changed.
177 The arg5 argument is ignored.
179 This operation is exposed by libkeyutils via the function
181 keyctl_chown(3).
182 KEYCTL_SETPERM (since Linux 2.6.10)
184 Change the permissions of the key with the ID provided in the
185 arg2 argument (cast to key_serial_t) to the permissions provided
186 in the arg3 argument (cast to key_perm_t).
187 If the caller doesn't have the CAP_SYS_ADMIN capability, it can
189 change permissions only for the keys it owns. (More precisely:
190 the caller's filesystem UID must match the UID of the key.)
191 The key must grant setattr permission to the caller regardless
193 of the caller's capabilities.
194 The permissions in arg3 specify masks of available operations
196 for each of the following user categories:
197 possessor (since Linux 2.6.14)
199 This is the permission granted to a process that pos‐
200 sesses the key (has it attached searchably to one of the
201 process's keyrings); see keyrings(7).
202 user This is the permission granted to a process whose
204 filesystem UID matches the UID of the key.
205 group This is the permission granted to a process whose
207 filesystem GID or any of its supplementary GIDs matches
208 the GID of the key.
209 other This is the permission granted to other processes that do
211 not match the user and group categories.
212 The user, group, and other categories are exclusive: if a
214 process matches the user category, it will not receive permis‐
215 sions granted in the group category; if a process matches the
216 user or group category, then it will not receive permissions
217 granted in the other category.
218 The possessor category grants permissions that are cumulative
220 with the grants from the user, group, or other category.
221 Each permission mask is eight bits in size, with only six bits
223 currently used. The available permissions are:
224 view This permission allows reading attributes of a key.
226 This permission is required for the KEYCTL_DESCRIBE oper‐
228 ation.
229 The permission bits for each category are KEY_POS_VIEW,
231 KEY_USR_VIEW, KEY_GRP_VIEW, and KEY_OTH_VIEW.
232 read This permission allows reading a key's payload.
234 This permission is required for the KEYCTL_READ opera‐
236 tion.
237 The permission bits for each category are KEY_POS_READ,
239 KEY_USR_READ, KEY_GRP_READ, and KEY_OTH_READ.
240 write This permission allows update or instantiation of a key's
242 payload. For a keyring, it allows keys to be linked and
243 unlinked from the keyring,
244 This permission is required for the KEYCTL_UPDATE,
246 KEYCTL_REVOKE, KEYCTL_CLEAR, KEYCTL_LINK, and
247 KEYCTL_UNLINK operations.
248 The permission bits for each category are KEY_POS_WRITE,
250 KEY_USR_WRITE, KEY_GRP_WRITE, and KEY_OTH_WRITE.
251 search This permission allows keyrings to be searched and keys
253 to be found. Searches can recurse only into nested
254 keyrings that have search permission set.
255 This permission is required for the
257 KEYCTL_GET_KEYRING_ID, KEYCTL_JOIN_SESSION_KEYRING,
258 KEYCTL_SEARCH, and KEYCTL_INVALIDATE operations.
259 The permission bits for each category are KEY_POS_SEARCH,
261 KEY_USR_SEARCH, KEY_GRP_SEARCH, and KEY_OTH_SEARCH.
262 link This permission allows a key or keyring to be linked to.
264 This permission is required for the KEYCTL_LINK and
266 KEYCTL_SESSION_TO_PARENT operations.
267 The permission bits for each category are KEY_POS_LINK,
269 KEY_USR_LINK, KEY_GRP_LINK, and KEY_OTH_LINK.
270 setattr (since Linux 2.6.15).
272 This permission allows a key's UID, GID, and permissions
273 mask to be changed.
274 This permission is required for the KEYCTL_REVOKE,
276 KEYCTL_CHOWN, and KEYCTL_SETPERM operations.
277 The permission bits for each category are
279 KEY_POS_SETATTR, KEY_USR_SETATTR, KEY_GRP_SETATTR, and
280 KEY_OTH_SETATTR.
281 As a convenience, the following macros are defined as masks for
283 all of the permission bits in each of the user categories:
284 KEY_POS_ALL, KEY_USR_ALL, KEY_GRP_ALL, and KEY_OTH_ALL.
285 The arg4 and arg5 arguments are ignored.
287 This operation is exposed by libkeyutils via the function
289 keyctl_setperm(3).
290 KEYCTL_DESCRIBE (since Linux 2.6.10)
292 Obtain a string describing the attributes of a specified key.
293 The ID of the key to be described is specified in arg2 (cast to
295 key_serial_t). The descriptive string is returned in the buffer
296 pointed to by arg3 (cast to char *); arg4 (cast to size_t) spec‐
297 ifies the size of that buffer in bytes.
298 The key must grant the caller view permission.
300 The returned string is null-terminated and contains the follow‐
302 ing information about the key:
303 type;uid;gid;perm;description
305 In the above, type and description are strings, uid and gid are
307 decimal strings, and perm is a hexadecimal permissions mask.
308 The descriptive string is written with the following format:
309 %s;%d;%d;%08x;%s
311 Note: the intention is that the descriptive string should be
313 extensible in future kernel versions. In particular, the
314 description field will not contain semicolons; it should be
315 parsed by working backwards from the end of the string to find
316 the last semicolon. This allows future semicolon-delimited
317 fields to be inserted in the descriptive string in the future.
318 Writing to the buffer is attempted only when arg3 is non-NULL
320 and the specified buffer size is large enough to accept the
321 descriptive string (including the terminating null byte). In
322 order to determine whether the buffer size was too small, check
323 to see if the return value of the operation is greater than
324 arg4.
325 The arg5 argument is ignored.
327 This operation is exposed by libkeyutils via the function
329 keyctl_describe(3).
330 KEYCTL_CLEAR
332 Clear the contents of (i.e., unlink all keys from) a keyring.
333 The ID of the key (which must be of keyring type) is provided in
335 arg2 (cast to key_serial_t).
336 The caller must have write permission on the keyring.
338 The arguments arg3, arg4, and arg5 are ignored.
340 This operation is exposed by libkeyutils via the function
342 keyctl_clear(3).
343 KEYCTL_LINK (since Linux 2.6.10)
345 Create a link from a keyring to a key.
346 The key to be linked is specified in arg2 (cast to
348 key_serial_t); the keyring is specified in arg3 (cast to
349 key_serial_t).
350 If a key with the same type and description is already linked in
352 the keyring, then that key is displaced from the keyring.
353 Before creating the link, the kernel checks the nesting of the
355 keyrings and returns appropriate errors if the link would pro‐
356 duce a cycle or if the nesting of keyrings would be too deep
357 (The limit on the nesting of keyrings is determined by the ker‐
358 nel constant KEYRING_SEARCH_MAX_DEPTH, defined with the value 6,
359 and is necessary to prevent overflows on the kernel stack when
360 recursively searching keyrings).
361 The caller must have link permission on the key being added and
363 write permission on the keyring.
364 The arguments arg4 and arg5 are ignored.
366 This operation is exposed by libkeyutils via the function
368 keyctl_link(3).
369 KEYCTL_UNLINK (since Linux 2.6.10)
371 Unlink a key from a keyring.
372 The ID of the key to be unlinked is specified in arg2 (cast to
374 key_serial_t); the ID of the keyring from which it is to be
375 unlinked is specified in arg3 (cast to key_serial_t).
376 If the key is not currently linked into the keyring, an error
378 results.
379 The caller must have write permission on the keyring from which
381 the key is being removed.
382 If the last link to a key is removed, then that key will be
384 scheduled for destruction.
385 The arguments arg4 and arg5 are ignored.
387 This operation is exposed by libkeyutils via the function
389 keyctl_unlink(3).
390 KEYCTL_SEARCH (since Linux 2.6.10)
392 Search for a key in a keyring tree, returning its ID and option‐
393 ally linking it to a specified keyring.
394 The tree to be searched is specified by passing the ID of the
396 head keyring in arg2 (cast to key_serial_t). The search is per‐
397 formed breadth-first and recursively.
398 The arg3 and arg4 arguments specify the key to be searched for:
400 arg3 (cast as char *) contains the key type (a null-terminated
401 character string up to 32 bytes in size, including the terminat‐
402 ing null byte), and arg4 (cast as char *) contains the descrip‐
403 tion of the key (a null-terminated character string up to 4096
404 bytes in size, including the terminating null byte).
405 The source keyring must grant search permission to the caller.
407 When performing the recursive search, only keyrings that grant
408 the caller search permission will be searched. Only keys with
409 for which the caller has search permission can be found.
410 If the key is found, its ID is returned as the function result.
412 If the key is found and arg5 (cast to key_serial_t) is nonzero,
414 then, subject to the same constraints and rules as KEYCTL_LINK,
415 the key is linked into the keyring whose ID is specified in
416 arg5. If the destination keyring specified in arg5 already con‐
417 tains a link to a key that has the same type and description,
418 then that link will be displaced by a link to the key found by
419 this operation.
420 Instead of valid existing keyring IDs, the source (arg2) and
422 destination (arg5) keyrings can be one of the special keyring
423 IDs listed under KEYCTL_GET_KEYRING_ID.
424 This operation is exposed by libkeyutils via the function
426 keyctl_search(3).
427 KEYCTL_READ (since Linux 2.6.10)
429 Read the payload data of a key.
430 The ID of the key whose payload is to be read is specified in
432 arg2 (cast to key_serial_t). This can be the ID of an existing
433 key, or any of the special key IDs listed for
434 KEYCTL_GET_KEYRING_ID.
435 The payload is placed in the buffer pointed by arg3 (cast to
437 char *); the size of that buffer must be specified in arg4 (cast
438 to size_t).
439 The returned data will be processed for presentation according
441 to the key type. For example, a keyring will return an array of
442 key_serial_t entries representing the IDs of all the keys that
443 are linked to it. The user key type will return its data as is.
444 If a key type does not implement this function, the operation
445 fails with the error EOPNOTSUPP.
446 If arg3 is not NULL, as much of the payload data as will fit is
448 copied into the buffer. On a successful return, the return
449 value is always the total size of the payload data. To deter‐
450 mine whether the buffer was of sufficient size, check to see
451 that the return value is less than or equal to the value sup‐
452 plied in arg4.
453 The key must either grant the caller read permission, or grant
455 the caller search permission when searched for from the process
456 keyrings (i.e., the key is possessed).
457 The arg5 argument is ignored.
459 This operation is exposed by libkeyutils via the function
461 keyctl_read(3).
462 KEYCTL_INSTANTIATE (since Linux 2.6.10)
464 (Positively) instantiate an uninstantiated key with a specified
465 payload.
466 The ID of the key to be instantiated is provided in arg2 (cast
468 to key_serial_t).
469 The key payload is specified in the buffer pointed to by arg3
471 (cast to void *); the size of that buffer is specified in arg4
472 (cast to size_t).
473 The payload may be a NULL pointer and the buffer size may be 0
475 if this is supported by the key type (e.g., it is a keyring).
476 The operation may be fail if the payload data is in the wrong
478 format or is otherwise invalid.
479 If arg5 (cast to key_serial_t) is nonzero, then, subject to the
481 same constraints and rules as KEYCTL_LINK, the instantiated key
482 is linked into the keyring whose ID specified in arg5.
483 The caller must have the appropriate authorization key, and once
485 the uninstantiated key has been instantiated, the authorization
486 key is revoked. In other words, this operation is available
487 only from a request-key(8)-style program. See request_key(2)
488 for an explanation of uninstantiated keys and key instantiation.
489 This operation is exposed by libkeyutils via the function
491 keyctl_instantiate(3).
492 KEYCTL_NEGATE (since Linux 2.6.10)
494 Negatively instantiate an uninstantiated key.
495 This operation is equivalent to the call:
497 keyctl(KEYCTL_REJECT, arg2, arg3, ENOKEY, arg4);
499 The arg5 argument is ignored.
501 This operation is exposed by libkeyutils via the function
503 keyctl_negate(3).
504 KEYCTL_SET_REQKEY_KEYRING (since Linux 2.6.13)
506 Set the default keyring to which implicitly requested keys will
507 be linked for this thread, and return the previous setting.
508 Implicit key requests are those made by internal kernel compo‐
509 nents, such as can occur when, for example, opening files on an
510 AFS or NFS filesystem. Setting the default keyring also has an
511 effect when requesting a key from user space; see request_key(2)
512 for details.
513 The arg2 argument (cast to int) should contain one of the fol‐
515 lowing values, to specify the new default keyring:
516 KEY_REQKEY_DEFL_NO_CHANGE
518 Don't change the default keyring. This can be used to
519 discover the current default keyring (without changing
520 it).
521 KEY_REQKEY_DEFL_DEFAULT
523 This selects the default behaviour, which is to use the
524 thread-specific keyring if there is one, otherwise the
525 process-specific keyring if there is one, otherwise the
526 session keyring if there is one, otherwise the UID-spe‐
527 cific session keyring, otherwise the user-specific
528 keyring.
529 KEY_REQKEY_DEFL_THREAD_KEYRING
531 Use the thread-specific keyring (thread-keyring(7)) as
532 the new default keyring.
533 KEY_REQKEY_DEFL_PROCESS_KEYRING
535 Use the process-specific keyring (process-keyring(7)) as
536 the new default keyring.
537 KEY_REQKEY_DEFL_SESSION_KEYRING
539 Use the session-specific keyring (session-keyring(7)) as
540 the new default keyring.
541 KEY_REQKEY_DEFL_USER_KEYRING
543 Use the UID-specific keyring (user-keyring(7)) as the new
544 default keyring.
545 KEY_REQKEY_DEFL_USER_SESSION_KEYRING
547 Use the UID-specific session keyring (user-session-
548 keyring(7)) as the new default keyring.
549 KEY_REQKEY_DEFL_REQUESTOR_KEYRING (since Linux 2.6.29)
551 Use the requestor keyring.
552 All other values are invalid.
554 The arguments arg3, arg4, and arg5 are ignored.
556 The setting controlled by this operation is inherited by the
558 child of fork(2) and preserved across execve(2).
559 This operation is exposed by libkeyutils via the function
561 keyctl_set_reqkey_keyring(3).
562 KEYCTL_SET_TIMEOUT (since Linux 2.6.16)
564 Set a timeout on a key.
565 The ID of the key is specified in arg2 (cast to key_serial_t).
567 The timeout value, in seconds from the current time, is speci‐
568 fied in arg3 (cast to unsigned int). The timeout is measured
569 against the realtime clock.
570 Specifying the timeout value as 0 clears any existing timeout on
572 the key.
573 The /proc/keys file displays the remaining time until each key
575 will expire. (This is the only method of discovering the time‐
576 out on a key.)
577 The caller must either have the setattr permission on the key or
579 hold an instantiation authorization token for the key (see
580 request_key(2)).
581 The key and any links to the key will be automatically garbage
583 collected after the timeout expires. Subsequent attempts to
584 access the key will then fail with the error EKEYEXPIRED.
585 This operation cannot be used to set timeouts on revoked,
587 expired, or negatively instantiated keys.
588 The arguments arg4 and arg5 are ignored.
590 This operation is exposed by libkeyutils via the function
592 keyctl_set_timeout(3).
593 KEYCTL_ASSUME_AUTHORITY (since Linux 2.6.16)
595 Assume (or divest) the authority for the calling thread to
596 instantiate a key.
597 The arg2 argument (cast to key_serial_t) specifies either a
599 nonzero key ID to assume authority, or the value 0 to divest
600 authority.
601 If arg2 is nonzero, then it specifies the ID of an uninstanti‐
603 ated key for which authority is to be assumed. That key can
604 then be instantiated using one of KEYCTL_INSTANTIATE,
605 KEYCTL_INSTANTIATE_IOV, KEYCTL_REJECT, or KEYCTL_NEGATE. Once
606 the key has been instantiated, the thread is automatically
607 divested of authority to instantiate the key.
608 Authority over a key can be assumed only if the calling thread
610 has present in its keyrings the authorization key that is asso‐
611 ciated with the specified key. (In other words, the
612 KEYCTL_ASSUME_AUTHORITY operation is available only from a
613 request-key(8)-style program; see request_key(2) for an explana‐
614 tion of how this operation is used.) The caller must have
615 search permission on the authorization key.
616 If the specified key has a matching authorization key, then the
618 ID of that key is returned. The authorization key can be read
619 (KEYCTL_READ) to obtain the callout information passed to
620 request_key(2).
621 If the ID given in arg2 is 0, then the currently assumed author‐
623 ity is cleared (divested), and the value 0 is returned.
624 The KEYCTL_ASSUME_AUTHORITY mechanism allows a program such as
626 request-key(8) to assume the necessary authority to instantiate
627 a new uninstantiated key that was created as a consequence of a
628 call to request_key(2). For further information, see
629 request_key(2) and the kernel source file Documentation/secu‐
630 rity/keys-request-key.txt.
631 The arguments arg3, arg4, and arg5 are ignored.
633 This operation is exposed by libkeyutils via the function
635 keyctl_assume_authority(3).
636 KEYCTL_GET_SECURITY (since Linux 2.6.26)
638 Get the LSM (Linux Security Module) security label of the speci‐
639 fied key.
640 The ID of the key whose security label is to be fetched is spec‐
642 ified in arg2 (cast to key_serial_t). The security label (ter‐
643 minated by a null byte) will be placed in the buffer pointed to
644 by arg3 argument (cast to char *); the size of the buffer must
645 be provided in arg4 (cast to size_t).
646 If arg3 is specified as NULL or the buffer size specified in
648 arg4 is too small, the full size of the security label string
649 (including the terminating null byte) is returned as the func‐
650 tion result, and nothing is copied to the buffer.
651 The caller must have view permission on the specified key.
653 The returned security label string will be rendered in a form
655 appropriate to the LSM in force. For example, with SELinux, it
656 may look like:
657 unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
659 If no LSM is currently in force, then an empty string is placed
661 in the buffer.
662 The arg5 argument is ignored.
664 This operation is exposed by libkeyutils via the functions
666 keyctl_get_security(3) and keyctl_get_security_alloc(3).
667 KEYCTL_SESSION_TO_PARENT (since Linux 2.6.32)
669 Replace the session keyring to which the parent of the calling
670 process subscribes with the session keyring of the calling
671 process.
672 The keyring will be replaced in the parent process at the point
674 where the parent next transitions from kernel space to user
675 space.
676 The keyring must exist and must grant the caller link permis‐
678 sion. The parent process must be single-threaded and have the
679 same effective ownership as this process and must not be set-
680 user-ID or set-group-ID. The UID of the parent process's exist‐
681 ing session keyring (f it has one), as well as the UID of the
682 caller's session keyring much match the caller's effective UID.
683 The fact that it is the parent process that is affected by this
685 operation allows a program such as the shell to start a child
686 process that uses this operation to change the shell's session
687 keyring. (This is what the keyctl(1) new_session command does.)
688 The arguments arg2, arg3, arg4, and arg5 are ignored.
690 This operation is exposed by libkeyutils via the function
692 keyctl_session_to_parent(3).
693 KEYCTL_REJECT (since Linux 2.6.39)
695 Mark a key as negatively instantiated and set an expiration
696 timer on the key. This operation provides a superset of the
697 functionality of the earlier KEYCTL_NEGATE operation.
698 The ID of the key that is to be negatively instantiated is spec‐
700 ified in arg2 (cast to key_serial_t). The arg3 (cast to
701 unsigned int) argument specifies the lifetime of the key, in
702 seconds. The arg4 argument (cast to unsigned int) specifies the
703 error to be returned when a search hits this key; typically,
704 this is one of EKEYREJECTED, EKEYREVOKED, or EKEYEXPIRED.
705 If arg5 (cast to key_serial_t) is nonzero, then, subject to the
707 same constraints and rules as KEYCTL_LINK, the negatively
708 instantiated key is linked into the keyring whose ID is speci‐
709 fied in arg5.
710 The caller must have the appropriate authorization key. In
712 other words, this operation is available only from a request-
713 key(8)-style program. See request_key(2).
714 The caller must have the appropriate authorization key, and once
716 the uninstantiated key has been instantiated, the authorization
717 key is revoked. In other words, this operation is available
718 only from a request-key(8)-style program. See request_key(2)
719 for an explanation of uninstantiated keys and key instantiation.
720 This operation is exposed by libkeyutils via the function
722 keyctl_reject(3).
723 KEYCTL_INSTANTIATE_IOV (since Linux 2.6.39)
725 Instantiate an uninstantiated key with a payload specified via a
726 vector of buffers.
727 This operation is the same as KEYCTL_INSTANTIATE, but the pay‐
729 load data is specified as an array of iovec structures:
730 struct iovec {
732 void *iov_base; /* Starting address of buffer */
733 size_t iov_len; /* Size of buffer (in bytes) */
734 };
735 The pointer to the payload vector is specified in arg3 (cast as
737 const struct iovec *). The number of items in the vector is
738 specified in arg4 (cast as unsigned int).
739 The arg2 (key ID) and arg5 (keyring ID) are interpreted as for
741 KEYCTL_INSTANTIATE.
742 This operation is exposed by libkeyutils via the function
744 keyctl_instantiate_iov(3).
745 KEYCTL_INVALIDATE (since Linux 3.5)
747 Mark a key as invalid.
748 The ID of the key to be invalidated is specified in arg2 (cast
750 to key_serial_t).
751 To invalidate a key, the caller must have search permission on
753 the key.
754 This operation marks the key as invalid and schedules immediate
756 garbage collection. The garbage collector removes the invali‐
757 dated key from all keyrings and deletes the key when its refer‐
758 ence count reaches zero. After this operation, the key will be
759 ignored by all searches, even if it is not yet deleted.
760 Keys that are marked invalid become invisible to normal key
762 operations immediately, though they are still visible in
763 /proc/keys (marked with an 'i' flag) until they are actually
764 removed.
765 The arguments arg3, arg4, and arg5 are ignored.
767 This operation is exposed by libkeyutils via the function
769 keyctl_invalidate(3).
770 KEYCTL_GET_PERSISTENT (since Linux 3.13)
772 Get the persistent keyring (persistent-keyring(7)) for a speci‐
773 fied user and link it to a specified keyring.
774 The user ID is specified in arg2 (cast to uid_t). If the value
776 -1 is specified, the caller's real user ID is used. The ID of
777 the destination keyring is specified in arg3 (cast to
778 key_serial_t).
779 The caller must have the CAP_SETUID capability in its user
781 namespace in order to fetch the persistent keyring for a user ID
782 that does not match either the real or effective user ID of the
783 caller.
784 If the call is successful, a link to the persistent keyring is
786 added to the keyring whose ID was specified in arg3.
787 The caller must have write permission on the keyring.
789 The persistent keyring will be created by the kernel if it does
791 not yet exist.
792 Each time the KEYCTL_GET_PERSISTENT operation is performed, the
794 persistent keyring will have its expiration timeout reset to the
795 value in:
796 /proc/sys/kernel/keys/persistent_keyring_expiry
798 Should the timeout be reached, the persistent keyring will be
800 removed and everything it pins can then be garbage collected.
801 Persistent keyrings were added to Linux in kernel version 3.13.
803 The arguments arg4 and arg5 are ignored.
805 This operation is exposed by libkeyutils via the function
807 keyctl_get_persistent(3).
808 KEYCTL_DH_COMPUTE (since Linux 4.7)
810 Compute a Diffie-Hellman shared secret or public key, optionally
811 applying key derivation function (KDF) to the result.
812 The arg2 argument is a pointer to a set of parameters containing
814 serial numbers for three "user" keys used in the Diffie-Hellman
815 calculation, packaged in a structure of the following form:
816 struct keyctl_dh_params {
818 int32_t private; /* The local private key */
819 int32_t prime; /* The prime, known to both parties */
820 int32_t base; /* The base integer: either a shared
821 generator or the remote public key */
822 };
823 Each of the three keys specified in this structure must grant
825 the caller read permission. The payloads of these keys are used
826 to calculate the Diffie-Hellman result as:
827 base ^ private mod prime
829 If the base is the shared generator, the result is the local
831 public key. If the base is the remote public key, the result is
832 the shared secret.
833 The arg3 argument (cast to char *) points to a buffer where the
835 result of the calculation is placed. The size of that buffer is
836 specified in arg4 (cast to size_t).
837 The buffer must be large enough to accommodate the output data,
839 otherwise an error is returned. If arg4 is specified zero, in
840 which case the buffer is not used and the operation returns the
841 minimum required buffer size (i.e., the length of the prime).
842 Diffie-Hellman computations can be performed in user space, but
844 require a multiple-precision integer (MPI) library. Moving the
845 implementation into the kernel gives access to the kernel MPI
846 implementation, and allows access to secure or acceleration
847 hardware.
848 Adding support for DH computation to the keyctl() system call
850 was considered a good fit due to the DH algorithm's use for
851 deriving shared keys; it also allows the type of the key to
852 determine which DH implementation (software or hardware) is
853 appropriate.
854 If the arg5 argument is NULL, then the DH result itself is
856 returned. Otherwise (since Linux 4.12), it is a pointer to a
857 structure which specifies parameters of the KDF operation to be
858 applied:
859 struct keyctl_kdf_params {
861 char *hashname; /* Hash algorithm name */
862 char *otherinfo; /* SP800-56A OtherInfo */
863 __u32 otherinfolen; /* Length of otherinfo data */
864 __u32 __spare[8]; /* Reserved */
865 };
866 The hashname field is a null-terminated string which specifies a
868 hash name (available in the kernel's crypto API; the list of the
869 hashes available is rather tricky to observe; please refer to
870 the "Kernel Crypto API Architecture" ⟨https://www.kernel.org/doc
871 /html/latest/crypto/architecture.html⟩ documentation for the
872 information regarding how hash names are constructed and your
873 kernel's source and configuration regarding what ciphers and
874 templates with type CRYPTO_ALG_TYPE_SHASH are available) to be
875 applied to DH result in KDF operation.
876 The otherinfo field is an OtherInfo data as described in
878 SP800-56A section 5.8.1.2 and is algorithm-specific. This data
879 is concatenated with the result of DH operation and is provided
880 as an input to the KDF operation. Its size is provided in the
881 otherinfolen field and is limited by KEYCTL_KDF_MAX_OI_LEN con‐
882 stant that defined in security/keys/internal.h to a value of 64.
883 The __spare field is currently unused. It was ignored until
885 Linux 4.13 (but still should be user-addressable since it is
886 copied to the kernel), and should contain zeros since Linux
887 4.13.
888 The KDF implementation complies with SP800-56A as well as with
890 SP800-108 (the counter KDF).
891 This operation is exposed by libkeyutils (from version 1.5.10
893 onwards) via the functions keyctl_dh_compute(3) and
894 keyctl_dh_compute_alloc(3).
895 KEYCTL_RESTRICT_KEYRING (since Linux 4.12)
897 Apply a key-linking restriction to the keyring with the ID pro‐
898 vided in arg2 (cast to key_serial_t). The caller must have
899 setattr permission on the key. If arg3 is NULL, any attempt to
900 add a key to the keyring is blocked; otherwise it contains a
901 pointer to a string with a key type name and arg4 contains a
902 pointer to string that describes the type-specific restriction.
903 As of Linux 4.12, only the type "asymmetric" has restrictions
904 defined:
905 builtin_trusted
907 Allows only keys that are signed by a key linked to the
908 built-in keyring (".builtin_trusted_keys").
909 builtin_and_secondary_trusted
911 Allows only keys that are signed by a key linked to the
912 secondary keyring (".secondary_trusted_keys") or, by
913 extension, a key in a built-in keyring, as the latter is
914 linked to the former.
915 key_or_keyring:key
917 key_or_keyring:key:chain
918 If key specifies the ID of a key of type "asymmetric",
919 then only keys that are signed by this key are allowed.
920 If key specifies the ID of a keyring, then only keys that
922 are signed by a key linked to this keyring are allowed.
923 If ":chain" is specified, keys that are signed by a keys
925 linked to the destination keyring (that is, the keyring
926 with the ID specified in the arg2 argument) are also
927 allowed.
928 Note that a restriction can be configured only once for the
930 specified keyring; once a restriction is set, it can't be over‐
931 ridden.
932 The argument arg5 is ignored.
934
936 For a successful call, the return value depends on the operation:
937 KEYCTL_GET_KEYRING_ID
939 The ID of the requested keyring.
940 KEYCTL_JOIN_SESSION_KEYRING
942 The ID of the joined session keyring.
943 KEYCTL_DESCRIBE
945 The size of the description (including the terminating null
946 byte), irrespective of the provided buffer size.
947 KEYCTL_SEARCH
949 The ID of the key that was found.
950 KEYCTL_READ
952 The amount of data that is available in the key, irrespective of
953 the provided buffer size.
954 KEYCTL_SET_REQKEY_KEYRING
956 The ID of the previous default keyring to which implicitly
957 requested keys were linked (one of KEY_REQKEY_DEFL_USER_*).
958 KEYCTL_ASSUME_AUTHORITY
960 Either 0, if the ID given was 0, or the ID of the authorization
961 key matching the specified key, if a nonzero key ID was pro‐
962 vided.
963 KEYCTL_GET_SECURITY
965 The size of the LSM security label string (including the termi‐
966 nating null byte), irrespective of the provided buffer size.
967 KEYCTL_GET_PERSISTENT
969 The ID of the persistent keyring.
970 KEYCTL_DH_COMPUTE
972 The number of bytes copied to the buffer, or, if arg4 is 0, the
973 required buffer size.
974 All other operations
976 Zero.
977 On error, -1 is returned, and errno is set appropriately to indicate
979 the error.
980
982 EACCES The requested operation wasn't permitted.
983 EAGAIN operation was KEYCTL_DH_COMPUTE and there was an error during
985 crypto module initialization.
986 EDEADLK
988 operation was KEYCTL_LINK and the requested link would result in
989 a cycle.
990 EDEADLK
992 operation was KEYCTL_RESTRICT_KEYRING and the requested keyring
993 restriction would result in a cycle.
994 EDQUOT The key quota for the caller's user would be exceeded by creat‐
996 ing a key or linking it to the keyring.
997 EEXIST operation was KEYCTL_RESTRICT_KEYRING and keyring provided in
999 arg2 argument already has a restriction set.
1000 EFAULT operation was KEYCTL_DH_COMPUTE and one of the following has
1002 failed:
1003 · copying of the struct keyctl_dh_params, provided in the arg2
1005 argument, from user space;
1006 · copying of the struct keyctl_kdf_params, provided in the non-
1008 NULL arg5 argument, from user space (in case kernel supports
1009 performing KDF operation on DH operation result);
1010 · copying of data pointed by the hashname field of the struct
1012 keyctl_kdf_params from user space;
1013 · copying of data pointed by the otherinfo field of the struct
1015 keyctl_kdf_params from user space if the otherinfolen field
1016 was nonzero;
1017 · copying of the result to user space.
1019 EINVAL operation was KEYCTL_SETPERM and an invalid permission bit was
1021 specified in arg3.
1022 EINVAL operation was KEYCTL_SEARCH and the size of the description in
1024 arg4 (including the terminating null byte) exceeded 4096 bytes.
1025 size of the string (including the terminating null byte) speci‐
1026 fied in arg3 (the key type) or arg4 (the key description)
1027 exceeded the limit (32 bytes and 4096 bytes respectively).
1028 EINVAL (Linux kernels before 4.12)
1030 operation was KEYCTL_DH_COMPUTE, argument arg5 was non-NULL.
1031 EINVAL operation was KEYCTL_DH_COMPUTE And the digest size of the hash‐
1033 ing algorithm supplied is zero.
1034 EINVAL operation was KEYCTL_DH_COMPUTE and the buffer size provided is
1036 not enough to hold the result. Provide 0 as a buffer size in
1037 order to obtain the minimum buffer size.
1038 EINVAL operation was KEYCTL_DH_COMPUTE and the hash name provided in
1040 the hashname field of the struct keyctl_kdf_params pointed by
1041 arg5 argument is too big (the limit is implementation-specific
1042 and varies between kernel versions, but it is deemed big enough
1043 for all valid algorithm names).
1044 EINVAL operation was KEYCTL_DH_COMPUTE and the __spare field of the
1046 struct keyctl_kdf_params provided in the arg5 argument contains
1047 nonzero values.
1048 EKEYEXPIRED
1050 An expired key was found or specified.
1051 EKEYREJECTED
1053 A rejected key was found or specified.
1054 EKEYREVOKED
1056 A revoked key was found or specified.
1057 ELOOP operation was KEYCTL_LINK and the requested link would cause the
1059 maximum nesting depth for keyrings to be exceeded.
1060 EMSGSIZE
1062 operation was KEYCTL_DH_COMPUTE and the buffer length exceeds
1063 KEYCTL_KDF_MAX_OUTPUT_LEN (which is 1024 currently) or the oth‐
1064 erinfolen field of the struct keyctl_kdf_parms passed in arg5
1065 exceeds KEYCTL_KDF_MAX_OI_LEN (which is 64 currently).
1066 ENFILE (Linux kernels before 3.13)
1068 operation was KEYCTL_LINK and the keyring is full. (Before
1069 Linux 3.13, the available space for storing keyring links was
1070 limited to a single page of memory; since Linux 3.13, there is
1071 no fixed limit.)
1072 ENOENT operation was KEYCTL_UNLINK and the key to be unlinked isn't
1074 linked to the keyring.
1075 ENOENT operation was KEYCTL_DH_COMPUTE and the hashing algorithm speci‐
1077 fied in the hashname field of the struct keyctl_kdf_params
1078 pointed by arg5 argument hasn't been found.
1079 ENOENT operation was KEYCTL_RESTRICT_KEYRING and the type provided in
1081 arg3 argument doesn't support setting key linking restrictions.
1082 ENOKEY No matching key was found or an invalid key was specified.
1084 ENOKEY The value KEYCTL_GET_KEYRING_ID was specified in operation, the
1086 key specified in arg2 did not exist, and arg3 was zero (meaning
1087 don't create the key if it didn't exist).
1088 ENOMEM One of kernel memory allocation routines failed during the exe‐
1090 cution of the syscall.
1091 ENOTDIR
1093 A key of keyring type was expected but the ID of a key with a
1094 different type was provided.
1095 EOPNOTSUPP
1097 operation was KEYCTL_READ and the key type does not support
1098 reading (e.g., the type is "login").
1099 EOPNOTSUPP
1101 operation was KEYCTL_UPDATE and the key type does not support
1102 updating.
1103 EOPNOTSUPP
1105 operation was KEYCTL_RESTRICT_KEYRING, the type provided in arg3
1106 argument was "asymmetric", and the key specified in the restric‐
1107 tion specification provided in arg4 has type other than "asym‐
1108 metric" or "keyring".
1109 EPERM operation was KEYCTL_GET_PERSISTENT, arg2 specified a UID other
1111 than the calling thread's real or effective UID, and the caller
1112 did not have the CAP_SETUID capability.
1113 EPERM operation was KEYCTL_SESSION_TO_PARENT and either: all of the
1115 UIDs (GIDs) of the parent process do not match the effective UID
1116 (GID) of the calling process; the UID of the parent's existing
1117 session keyring or the UID of the caller's session keyring did
1118 not match the effective UID of the caller; the parent process is
1119 not single-thread; or the parent process is init(1) or a kernel
1120 thread.
1121 ETIMEDOUT
1123 operation was KEYCTL_DH_COMPUTE and the initialization of crypto
1124 modules has timed out.
1125
1127 This system call first appeared in Linux 2.6.10.
1128
1130 This system call is a nonstandard Linux extension.
1131
1133 No wrapper for this system call is provided in glibc. A wrapper is
1134 provided in the libkeyutils library. When employing the wrapper in
1135 that library, link with -lkeyutils. However, rather than using this
1136 system call directly, you probably want to use the various library
1137 functions mentioned in the descriptions of individual operations above.
1138
1140 The program below provide subset of the functionality of the request-
1141 key(8) program provided by the keyutils package. For informational
1142 purposes, the program records various information in a log file.
1143 As described in request_key(2), the request-key(8) program is invoked
1145 with command-line arguments that describe a key that is to be instanti‐
1146 ated. The example program fetches and logs these arguments. The pro‐
1147 gram assumes authority to instantiate the requested key, and then
1148 instantiates that key.
1149 The following shell session demonstrates the use of this program. In
1151 the session, we compile the program and then use it to temporarily
1152 replace the standard request-key(8) program. (Note that temporarily
1153 disabling the standard request-key(8) program may not be safe on some
1154 systems.) While our example program is installed, we use the example
1155 program shown in request_key(2) to request a key.
1156 $ cc -o key_instantiate key_instantiate.c -lkeyutils
1158 $ sudo mv /sbin/request-key /sbin/request-key.backup
1159 $ sudo cp key_instantiate /sbin/request-key
1160 $ ./t_request_key user mykey somepayloaddata
1161 Key ID is 20d035bf
1162 $ sudo mv /sbin/request-key.backup /sbin/request-key
1163 Looking at the log file created by this program, we can see the com‐
1165 mand-line arguments supplied to our example program:
1166 $ cat /tmp/key_instantiate.log
1168 Time: Mon Nov 7 13:06:47 2016
1169 Command line arguments:
1171 argv[0]: /sbin/request-key
1172 operation: create
1173 key_to_instantiate: 20d035bf
1174 UID: 1000
1175 GID: 1000
1176 thread_keyring: 0
1177 process_keyring: 0
1178 session_keyring: 256e6a6
1179 Key description: user;1000;1000;3f010000;mykey
1181 Auth key payload: somepayloaddata
1182 Destination keyring: 256e6a6
1183 Auth key description: .request_key_auth;1000;1000;0b010000;20d035bf
1184 The last few lines of the above output show that the example program
1186 was able to fetch:
1187 * the description of the key to be instantiated, which included the
1189 name of the key (mykey);
1190 * the payload of the authorization key, which consisted of the data
1192 (somepayloaddata) passed to request_key(2);
1193 * the destination keyring that was specified in the call to
1195 request_key(2); and
1196 * the description of the authorization key, where we can see that the
1198 name of the authorization key matches the ID of the key that is to
1199 be instantiated (20d035bf).
1200 The example program in request_key(2) specified the destination keyring
1202 as KEY_SPEC_SESSION_KEYRING. By examining the contents of /proc/keys,
1203 we can see that this was translated to the ID of the destination
1204 keyring (0256e6a6) shown in the log output above; we can also see the
1205 newly created key with the name mykey and ID 20d035bf.
1206 $ cat /proc/keys | egrep 'mykey|256e6a6'
1208 0256e6a6 I--Q--- 194 perm 3f030000 1000 1000 keyring _ses: 3
1209 20d035bf I--Q--- 1 perm 3f010000 1000 1000 user mykey: 16
1210 Program source
1212 /* key_instantiate.c */
1214 #include <sys/types.h>
1216 #include <keyutils.h>
1217 #include <time.h>
1218 #include <fcntl.h>
1219 #include <stdio.h>
1220 #include <stdlib.h>
1221 #include <unistd.h>
1222 #include <string.h>
1223 #include <errno.h>
1224 #ifndef KEY_SPEC_REQUESTOR_KEYRING
1226 #define KEY_SPEC_REQUESTOR_KEYRING -8
1227 #endif
1228 int
1230 main(int argc, char *argv[])
1231 {
1232 FILE *fp;
1233 time_t t;
1234 char *operation;
1235 key_serial_t key_to_instantiate, dest_keyring;
1236 key_serial_t thread_keyring, process_keyring, session_keyring;
1237 uid_t uid;
1238 gid_t gid;
1239 char dbuf[256];
1240 char auth_key_payload[256];
1241 int akp_size; /* Size of auth_key_payload */
1242 fp = fopen("/tmp/key_instantiate.log", "w");
1244 if (fp == NULL)
1245 exit(EXIT_FAILURE);
1246 setbuf(fp, NULL);
1248 t = time(NULL);
1250 fprintf(fp, "Time: %s\n", ctime(&t));
1251 /*
1253 * The kernel passes a fixed set of arguments to the program
1254 * that it execs; fetch them.
1255 */
1256 operation = argv[1];
1257 key_to_instantiate = atoi(argv[2]);
1258 uid = atoi(argv[3]);
1259 gid = atoi(argv[4]);
1260 thread_keyring = atoi(argv[5]);
1261 process_keyring = atoi(argv[6]);
1262 session_keyring = atoi(argv[7]);
1263 fprintf(fp, "Command line arguments:\n");
1265 fprintf(fp, " argv[0]: %s\n", argv[0]);
1266 fprintf(fp, " operation: %s\n", operation);
1267 fprintf(fp, " key_to_instantiate: %lx\n",
1268 (long) key_to_instantiate);
1269 fprintf(fp, " UID: %ld\n", (long) uid);
1270 fprintf(fp, " GID: %ld\n", (long) gid);
1271 fprintf(fp, " thread_keyring: %lx\n", (long) thread_keyring);
1272 fprintf(fp, " process_keyring: %lx\n", (long) process_keyring);
1273 fprintf(fp, " session_keyring: %lx\n", (long) session_keyring);
1274 fprintf(fp, "\n");
1275 /*
1277 * Assume the authority to instantiate the key named in argv[2]
1278 */
1279 if (keyctl(KEYCTL_ASSUME_AUTHORITY, key_to_instantiate) == -1) {
1280 fprintf(fp, "KEYCTL_ASSUME_AUTHORITY failed: %s\n",
1281 strerror(errno));
1282 exit(EXIT_FAILURE);
1283 }
1284 /*
1286 * Fetch the description of the key that is to be instantiated
1287 */
1288 if (keyctl(KEYCTL_DESCRIBE, key_to_instantiate,
1289 dbuf, sizeof(dbuf)) == -1) {
1290 fprintf(fp, "KEYCTL_DESCRIBE failed: %s\n", strerror(errno));
1291 exit(EXIT_FAILURE);
1292 }
1293 fprintf(fp, "Key description: %s\n", dbuf);
1295 /*
1297 * Fetch the payload of the authorization key, which is
1298 * actually the callout data given to request_key()
1299 */
1300 akp_size = keyctl(KEYCTL_READ, KEY_SPEC_REQKEY_AUTH_KEY,
1301 auth_key_payload, sizeof(auth_key_payload));
1302 if (akp_size == -1) {
1303 fprintf(fp, "KEYCTL_READ failed: %s\n", strerror(errno));
1304 exit(EXIT_FAILURE);
1305 }
1306 auth_key_payload[akp_size] = '\0';
1308 fprintf(fp, "Auth key payload: %s\n", auth_key_payload);
1309 /*
1311 * For interest, get the ID of the authorization key and
1312 * display it.
1313 */
1314 auth_key = keyctl(KEYCTL_GET_KEYRING_ID,
1315 KEY_SPEC_REQKEY_AUTH_KEY);
1316 if (auth_key == -1) {
1317 fprintf(fp, "KEYCTL_GET_KEYRING_ID failed: %s\n",
1318 strerror(errno));
1319 exit(EXIT_FAILURE);
1320 }
1321 fprintf(fp, "Auth key ID: %lx\n", (long) auth_key);
1323 /*
1325 * Fetch key ID for the request_key(2) destination keyring.
1326 */
1327 dest_keyring = keyctl(KEYCTL_GET_KEYRING_ID,
1328 KEY_SPEC_REQUESTOR_KEYRING);
1329 if (dest_keyring == -1) {
1330 fprintf(fp, "KEYCTL_GET_KEYRING_ID failed: %s\n",
1331 strerror(errno));
1332 exit(EXIT_FAILURE);
1333 }
1334 fprintf(fp, "Destination keyring: %lx\n", (long) dest_keyring);
1336 /*
1338 * Fetch the description of the authorization key. This
1339 * allows us to see the key type, UID, GID, permissions,
1340 * and description (name) of the key. Among other things,
1341 * we will see that the name of the key is a hexadecimal
1342 * string representing the ID of the key to be instantiated.
1343 */
1344 if (keyctl(KEYCTL_DESCRIBE, KEY_SPEC_REQKEY_AUTH_KEY,
1345 dbuf, sizeof(dbuf)) == -1) {
1346 fprintf(fp, "KEYCTL_DESCRIBE failed: %s\n", strerror(errno));
1347 exit(EXIT_FAILURE);
1348 }
1349 fprintf(fp, "Auth key description: %s\n", dbuf);
1351 /*
1353 * Instantiate the key using the callout data that was supplied
1354 * in the payload of the authorization key.
1355 */
1356 if (keyctl(KEYCTL_INSTANTIATE, key_to_instantiate,
1357 auth_key_payload, akp_size + 1, dest_keyring) == -1) {
1358 fprintf(fp, "KEYCTL_INSTANTIATE failed: %s\n",
1359 strerror(errno));
1360 exit(EXIT_FAILURE);
1361 }
1362 exit(EXIT_SUCCESS);
1364 }
1365
1367 keyctl(1), add_key(2), request_key(2), keyctl(3),
1368 keyctl_assume_authority(3), keyctl_chown(3), keyctl_clear(3),
1369 keyctl_describe(3), keyctl_describe_alloc(3), keyctl_dh_compute(3),
1370 keyctl_dh_compute_alloc(3), keyctl_get_keyring_ID(3),
1371 keyctl_get_persistent(3), keyctl_get_security(3),
1372 keyctl_get_security_alloc(3), keyctl_instantiate(3),
1373 keyctl_instantiate_iov(3), keyctl_invalidate(3),
1374 keyctl_join_session_keyring(3), keyctl_link(3), keyctl_negate(3),
1375 keyctl_read(3), keyctl_read_alloc(3), keyctl_reject(3),
1376 keyctl_revoke(3), keyctl_search(3), keyctl_session_to_parent(3),
1377 keyctl_set_reqkey_keyring(3), keyctl_set_timeout(3), keyctl_setperm(3),
1378 keyctl_unlink(3), keyctl_update(3), recursive_key_scan(3),
1379 recursive_session_key_scan(3), capabilities(7), credentials(7),
1380 keyrings(7), keyutils(7), persistent-keyring(7), process-keyring(7),
1381 session-keyring(7), thread-keyring(7), user-keyring(7),
1382 user_namespaces(7), user-session-keyring(7), request-key(8)
1383 The kernel source files under Documentation/security/keys/ (or, before
1385 Linux 4.13, in the file Documentation/security/keys.txt).
1386
1388 This page is part of release 5.07 of the Linux man-pages project. A
1389 description of the project, information about reporting bugs, and the
1390 latest version of this page, can be found at
1391 https://www.kernel.org/doc/man-pages/.
1392Linux 2020-06-09 KEYCTL(2)