Kernel::Keyring - Wrapper for kernel keyring syscalls
use Kernel::Keyring;
use utf8;
use Encode;
# create keyring for current session with name 'Test'
key_session 'Test';
# add new user type key named 'password' with data 'secretPW' in session keyring (@s)
my $id = key_add 'user', 'password', 'secretPW', '@s';
# same with wide characters
my $id2 = key_add 'user', 'secret_name', Encode::encode('UTF-8', '刘维克多'), '@s';
# retrieve data for given id
my $data = key_get_by_id $id;
# set timeout on key to 60 seconds
key_timeout $id, 60;
# clear timeout
key_timeout $id, 0;
# set key permissions to all for possessor, none for anyone else
key_perm $id, 0x3f000000;
# revoke access to key
key_revoke $id;
# delete key for given keyring
key_unlink $id, '@s';
Kernel::Keyring is a rudimentary wrapper for libkeyutils based syscalls. Provided functions should suffice for the typical use case: storing passwords/keys in a secure location, the kernel. Data stored in the kernel keyring doesn't get swapped to disk (unless big_key type is used) and it can automatically time out.
A general overview of the keyring facility is given here: http://man7.org/linux/man-pages/man7/keyrings.7.html
More documentation is available on the man page of keyctl http://man7.org/linux/man-pages/man1/keyctl.1.html
Module exports all functions by default.
All functions "die" with a proper message on errors.
The module requires kernel support and the keyutils library to be installed.
- Package names for Ubuntu/Debian:
libkeyutils-devlibkeyutils1 - Package names for RedHat:
keyutils-develkeyutils-libs - Source as tar: http://people.redhat.com/~dhowells/keyutils/
key_add($type, $name, $data, $keyring)
Adds key with given type, name and data to the keyring.
$type is usually the string user, more info on the man page of keyctl.
$name is the name of the key, can be used for searching (not implemented yet).
$data is an arbitrary string of data. Strings with wide characters should be encoded to ensure proper string length.
Else data might appear truncated on key retrieval.
$keyring can be be any of the following:
- Thread keyring:
@t - Process keyring:
@p - Session keyring:
@s - User specific keyring:
@u - User default session keyring:
@us - Group specific keyring:
@g
The function returns the assigned key id on success, dies on error.
Corresponds to keyctl add <type> <desc> <data> <keyring> shell command from keyutils package
key_add($id)
Retrieves key string with given id.
Corresponds to keyctl read <key> shell command from keyutils package
key_timeout($id, $seconds)
Sets timeout on given id in seconds. Kernel automatically unlinks timed out keys.
Corresponds to keyctl timeout <key> <timeout> shell command from keyutils package
key_unlink($id, $keyring)
Deletes key with given id from given keyring (e.g. @s). Supports only the two argument version for fast lookups.
Corresponds to keyctl unlink <key> <keyring> shell command from keyutils package
key_session($name)
Creates a new keyring and attaches it to the current session. Doesn't place the program in a new shell, unlike the keyctl command.
This function might be necessary for unattended applications, like server software.
Without calling key_session first the session keyring is destroyed on user logout (after starting the app), resulting in "Key has been revoked" error messages.
Omitting $name will result in the keyring name defaulting to a random 32bit number appended to "K::KR::" (seen in file /proc/keys).
Corresponds to keyctl session <name> shell command from keyutils package
key_perm($id, $mask)
Sets permission on given key id.
Mask should be given in hex format
as a combination of (following paragraph taken from man page of keyctl):
Possessor UID GID Other Permission Granted
======== ======== ======== ======== ==================
01000000 00010000 00000100 00000001 View
02000000 00020000 00000200 00000002 Read
04000000 00040000 00000400 00000004 Write
08000000 00080000 00000800 00000008 Search
10000000 00100000 00001000 00000010 Link
20000000 00200000 00002000 00000020 Set Attribute
3f000000 003f0000 00003f00 0000003f All
View permits the type, description and other parameters of a key to be viewed.
Read permits the payload (or keyring list) to be read if supported by the type.
Write permits the payload (or keyring list) to be modified or updated.
Search on a key permits it to be found when a keyring to which it is linked is searched.
Link permits a key to be linked to a keyring.
Set Attribute permits a key to have its owner, group membership, permissions mask and timeout changed.
Corresponds to keyctl setperm <key> <mask> shell command from keyutils package
key_revoke($id)
Revokes access to the key with given id. No operations other than unlink are possible on revoked keys.
Corresponds to keyctl revoke <key> shell command from keyutils package
http://github.com/lixmal/Kernel-Keyring
Viktor Liu lixmal@cpan.org
Copyright (C) 2016-2017 Viktor Liu
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Details can be found in the file LICENSE.