request_key(2)

1REQUEST_KEY(2)            Linux Key Management Calls            REQUEST_KEY(2)
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NAME

6       request_key - Request a key from the kernel's key management facility
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SYNOPSIS

9       #include <keyutils.h>
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11       key_serial_t request_key(const char *type, const char *description,
12       const char *callout_info, key_serial_t keyring);
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DESCRIPTION

15       request_key()  asks  the  kernel  to  find a key of the given type that
16       matches the specified description and, if successful, to attach  it  to
17       the nominated keyring and to return its serial number.
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19       request_key()  first  recursively searches all the keyrings attached to
20       the calling process in the order thread-specific keyring,  process-spe‐
21       cific keyring and then session keyring for a matching key.
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23       If  request_key()  is called from a program invoked by request_key() on
24       behalf of some other process to generate a key, then  the  keyrings  of
25       that  other  process  will be searched next, using that other process's
26       UID, GID, groups and security context to control access.
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28       The keys in each keyring searched are checked for a  match  before  any
29       child  keyrings  are  recursed into.  Only keys that are searchable for
30       the caller may be found, and only searchable keyrings may be searched.
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32       If the key is not found then, if callout_info  is  set,  this  function
33       will  attempt to look further afield.  In such a case, the callout_info
34       is passed to a userspace service such as /sbin/request-key to  generate
35       the key.
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37       If  that  is  unsuccessful  also, then an error will be returned, and a
38       temporary negative key will be  installed  in  the  nominated  keyring.
39       This  will  expire after a few seconds, but will cause subsequent calls
40       to request_key() to fail until it does.
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42       The keyring serial number may be that of a valid keyring to  which  the
43       caller has write permission, or it may be a special keyring ID:
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45       KEY_SPEC_THREAD_KEYRING
46              This specifies the caller's thread-specific keyring.
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48       KEY_SPEC_PROCESS_KEYRING
49              This specifies the caller's process-specific keyring.
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51       KEY_SPEC_SESSION_KEYRING
52              This specifies the caller's session-specific keyring.
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54       KEY_SPEC_USER_KEYRING
55              This specifies the caller's UID-specific keyring.
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57       KEY_SPEC_USER_SESSION_KEYRING
58              This specifies the caller's UID-session keyring.
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60       If  a  key is created, no matter whether it's a valid key or a negative
61       key, it will displace any other key of the same  type  and  description
62       from the destination keyring.
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RETURN VALUE

65       On success request_key() returns the serial number of the key it found.
66       On error, the value -1 will be returned and errno will have been set to
67       an appropriate error.
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ERRORS

70       ENOKEY No matching key was found.
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72       EKEYEXPIRED
73              An expired key was found, but no replacement could be obtained.
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75       EKEYREVOKED
76              A revoked key was found, but no replacement could be obtained.
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78       EKEYREJECTED
79              The attempt to generate a new key was rejected.
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81       ENOMEM Insufficient memory to create a key.
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83       EINTR  The request was interrupted by a signal.
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85       EDQUOT The  key  quota for this user would be exceeded by creating this
86              key or linking it to the keyring.
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88       EACCES The keyring wasn't available for modification by the user.
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LINKING

91       Although this is a Linux system call, it is not present in libc but can
92       be  found  rather  in  libkeyutils.  When linking, -lkeyutils should be
93       specified to the linker.
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NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

LINKING

SEE ALSO