1REQUEST_KEY(2) Linux Key Management Calls REQUEST_KEY(2)
2
6 request_key - request a key from the kernel's key management facility
7
9 #include <keyutils.h>
10 key_serial_t request_key(const char *type, const char *description,
12 const char *callout_info,
13 key_serial_t keyring);
14
16 request_key() asks the kernel to find a key of the given type that
17 matches the specified description and, if successful, to attach it to
18 the nominated keyring and to return its serial number.
19 request_key() first recursively searches all the keyrings attached to
21 the calling process in the order thread-specific keyring, process-spe‐
22 cific keyring and then session keyring for a matching key.
23 If request_key() is called from a program invoked by request_key() on
25 behalf of some other process to generate a key, then the keyrings of
26 that other process will be searched next, using that other process's
27 UID, GID, groups and security context to control access.
28 The keys in each keyring searched are checked for a match before any
30 child keyrings are recursed into. Only keys that are searchable for
31 the caller may be found, and only searchable keyrings may be searched.
32 If the key is not found then, if callout_info is set, this function
34 will attempt to look further afield. In such a case, the callout_info
35 is passed to a user-space service such as /sbin/request-key to generate
36 the key.
37 If that is unsuccessful also, then an error will be returned, and a
39 temporary negative key will be installed in the nominated keyring.
40 This will expire after a few seconds, but will cause subsequent calls
41 to request_key() to fail until it does.
42 The keyring serial number may be that of a valid keyring to which the
44 caller has write permission, or it may be a special keyring ID:
45 KEY_SPEC_THREAD_KEYRING
47 This specifies the caller's thread-specific keyring.
48 KEY_SPEC_PROCESS_KEYRING
50 This specifies the caller's process-specific keyring.
51 KEY_SPEC_SESSION_KEYRING
53 This specifies the caller's session-specific keyring.
54 KEY_SPEC_USER_KEYRING
56 This specifies the caller's UID-specific keyring.
57 KEY_SPEC_USER_SESSION_KEYRING
59 This specifies the caller's UID-session keyring.
60 If a key is created, no matter whether it's a valid key or a negative
62 key, it will displace any other key of the same type and description
63 from the destination keyring.
64
66 On success request_key() returns the serial number of the key it found.
67 On error, the value -1 will be returned and errno will have been set to
68 an appropriate error.
69
71 EACCES The keyring wasn't available for modification by the user.
72 EINTR The request was interrupted by a signal.
74 EDQUOT The key quota for this user would be exceeded by creating this
76 key or linking it to the keyring.
77 EKEYEXPIRED
79 An expired key was found, but no replacement could be obtained.
80 EKEYREJECTED
82 The attempt to generate a new key was rejected.
83 EKEYREVOKED
85 A revoked key was found, but no replacement could be obtained.
86 ENOMEM Insufficient memory to create a key.
88 ENOKEY No matching key was found.
90
92 Although this is a Linux system call, it is not present in libc but can
93 be found rather in libkeyutils. When linking, -lkeyutils should be
94 specified to the linker.
95
97 keyctl(1), add_key(2), keyctl(2), request-key(8)
98
100 This page is part of release 3.53 of the Linux man-pages project. A
101 description of the project, and information about reporting bugs, can
102 be found at http://www.kernel.org/doc/man-pages/.
103Linux 2010-02-25 REQUEST_KEY(2)