.\"
.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
.\" Copyright (C) 2017 Intel Corporation. All rights reserved.
.\"
.\" This program is free software; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License
.\" as published by the Free Software Foundation; either version
.\" 2 of the License, or (at your option) any later version.
.\"
.TH KEYCTL_RESTRICT_KEYRING 3 "28 Feb 2017" Linux "Linux Key Management Calls"
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.SH NAME
keyctl_restrict_keyring \- restrict keys that may be linked to a keyring
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.SH SYNOPSIS
.nf
.B #include <keyutils.h>
.sp
.BI "long keyctl_restrict_keyring(key_serial_t " keyring ,
.BI "const char *" type ", const char *" restriction ");"
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.SH DESCRIPTION
.BR keyctl_restrict_keyring ()
limits the linkage of keys to the given
.I keyring
using a provided key
.I type
and
.I restriction
scheme. The available options vary depending on the key type, and
typically contain a restriction name possibly followed by key ids or
other data relevant to the restriction. If the type and restriction are
both
.B NULL,
the keyring will reject all links.
.P
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.SH RETURN VALUE
On success
.BR keyctl_restrict_keyring ()
returns
.BR 0 .
On error, the value
.B -1
will be returned and
.I errno
will have been set to an appropriate error.
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.SH ERRORS
.TP
.B EDEADLK
A restriction cycle was avoided. Two keyrings cannot restrict each other.
.TP
.B EEXIST
The keyring is already restricted.
.TP
.B EINVAL
The restriction string is invalid or too large.
.TP
.B ENOKEY
The key type in the restriction is invalid or not available.
.TP
.B ENOTDIR
The provided key id references an item that is not a keyring.
.TP
.B ENOENT
The key type exists but does not support restrictions.
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.SH LINKING
This is a library function that can be found in
.IR libkeyutils .
When linking,
.B \-lkeyutils
should be specified to the linker.
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.SH SEE ALSO
.ad l
.nh
.BR keyctl (1),
.BR keyctl (2),
.BR keyctl (3),
.BR keyutils (7)