1KEYCTL_INSTANTIATE(3) Linux Key Management Calls KEYCTL_INSTANTIATE(3)
2
6 keyctl_assume_authority - Assume the authority to instantiate a key
7 keyctl_instantiate - Instantiate a key keyctl_negate - Negatively
8 instantiate a key
9
11 #include <keyutils.h>
12 long keyctl_assume_authority(key_serial_t key);
14 long keyctl_instantiate(key_serial_t key, const char *payload,
16 size_t plen, key_serial_t keyring);
17 long keyctl_negate(key_serial_t key, unsigned timeout,
19 key_serial_t keyring);
20
22 keyctl_assume_authority() assumes the authority for the calling thread
23 to deal with and instantiate the specified uninstantiated key.
24 The calling thread must have the appopriate authorisation key resident
26 in one of its keyrings for this to succeed, and that authority must not
27 have been revoked.
28 The authorising key is allocated by request_key() when it needs to
30 invoke userspace to generate a key for the requesting process. This is
31 then attached to one of the keyrings of the userspace process to which
32 the task of instantiating the key is given:
33 requester -> request_key() -> instantiator
35 Calling this function modifies the way request_key() works when called
37 thereafter by the calling (instantiator) thread; once the authority is
38 assumed, the keyrings of the initial process are added to the search
39 path, using the initial process's UID, GID, groups and security con‐
40 text.
41 If a thread has multiple instantiations to deal with, it may call this
43 function to change the authorisation key currently in effect. Supply‐
44 ing a zero key de-assumes the currently assumed authority.
45 NOTE! This is a per-thread setting and not a per-process setting so
47 that a multithreaded process can be used to instantiate several keys at
48 once.
49 keyctl_instantiate() instantiates the payload of an uninstantiated key
51 from the data specified. payload and plen specify the data for the new
52 payload. payload may be NULL and plen may be zero if the key type per‐
53 mits that. The key type may reject the data if it's in the wrong for‐
54 mat or in some other way invalid.
55 keyctl_negate() marks a key as negatively instantiated and sets the
57 expiration timer on it. timeout specifies the lifetime of the key in
58 seconds.
59 Only a key for which authority has been assumed may be instantiated or
61 negatively instantiated, and once instantiated, the authorisation key
62 will be revoked and the requesting process will be able to resume.
63 The destination keyring, if given, is assumed to belong to the initial
65 requester, and not the instantiating process. Therefore, the special
66 keyring IDs refer to the requesting process's keyrings, not the call‐
67 er's, and the requester's UID, etc. will be used to access them.
68 The destination keyring can be zero if no extra link is desired.
70 The requester, not the caller, must have write permission on the desti‐
72 nation for a link to be made there.
73
75 On success keyctl_instantiate() returns 0. On error, the value -1 will
76 be returned and errno will have been set to an appropriate error.
77
79 ENOKEY The key or keyring specified is invalid.
80 EKEYEXPIRED
82 The keyring specified has expired.
83 EKEYREVOKED
85 The key or keyring specified had been revoked, or the authorisa‐
86 tion has been revoked.
87 EINVAL The payload data was invalid.
89 ENOMEM Insufficient memory to store the new payload or to expand the
91 destination keyring.
92 EDQUOT The key quota for the key's user would be exceeded by increasing
94 the size of the key to accommodate the new payload or the key
95 quota for the keyring's user would be exceeded by expanding the
96 destination keyring.
97 EACCES The key exists, but is not writable by the requester.
99
101 This is a library function that can be found in libkeyutils. When
102 linking, -lkeyutils should be specified to the linker.
103
105 keyctl(1),
106 add_key(2),
107 keyctl(2),
108 request_key(2),
109 keyctl(3),
110 request-key(8)
111Linux 4 May 2006 KEYCTL_INSTANTIATE(3)