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# NAME Kernel::Keyring - Wrapper for kernel keyring syscalls # SYNOPSIS 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 $id, '@s'; # DESCRIPTION [Kernel::Keyring]( is a rudimentary wrapper for libkeyutils based syscalls. Provided functions should suffice for the typical use case: storing passwords/keys in a secure location, the kernel. Data stored in the kernel keyring doesn't get swapped to disk (unless big\_key type is used) and it can automatically time out. A general overview of the keyring facility is given here: []( More documentation is available on the man page of keyctl []( Module exports all functions by default. All functions "die" with a proper message on errors. # PREREQUISITES The module requires kernel support and the `keyutils` library to be installed. - Package names for Ubuntu/Debian: `libkeyutils-dev` `libkeyutils1` - Package names for RedHat: `keyutils-devel` `keyutils-libs` - Source as tar: []( # FUNCTIONS ### key\_add key_add($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. `$keyring` can be be any of the following: - Thread keyring: `@t` - Process keyring: `@p` - Session keyring: `@s` - User specific keyring: `@u` - User default session keyring: `@us` - Group specific keyring: `@g` The function returns the assigned key id on success, dies on error. Corresponds to `keyctl add ` shell command from keyutils package ### key\_get\_by\_id key_add($id) Retrieves key string with given id. Corresponds to `keyctl read ` shell command from keyutils package ### key\_timeout key_timeout($id, $seconds) Sets timeout on given id in seconds. Kernel automatically unlinks timed out keys. Corresponds to `keyctl timeout ` shell command from keyutils package ### key\_unlink key_unlink($id, $keyring) Deletes key with given id from given keyring (e.g. `@s`). Supports only the two argument version for fast lookups. Corresponds to `keyctl unlink ` shell command from keyutils package ### key\_session key_session($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 `$name` will result in the keyring name defaulting to a random 32bit number appended to "K::KR::" (seen in file /proc/keys). Corresponds to `keyctl session ` shell command from keyutils package ### key\_perm key_perm($id, $mask) Sets permission on given key id. Mask should be given in hex format as a combination of (following paragraph taken from man page of `keyctl`: Possessor UID GID Other Permission Granted ======== ======== ======== ======== ================== 01000000 00010000 00000100 00000001 View 02000000 00020000 00000200 00000002 Read 04000000 00040000 00000400 00000004 Write 08000000 00080000 00000800 00000008 Search 10000000 00100000 00001000 00000010 Link 20000000 00200000 00002000 00000020 Set Attribute 3f000000 003f0000 00003f00 0000003f All `View` permits the type, description and other parameters of a key to be viewed. `Read` permits the payload (or keyring list) to be read if supported by the type. `Write` permits the payload (or keyring list) to be modified or updated. `Search` on a key permits it to be found when a keyring to which it is linked is searched. `Link` permits a key to be linked to a keyring. `Set Attribute` permits a key to have its owner, group membership, permissions mask and timeout changed. Corresponds to `keyctl setperm ` shell command from keyutils package ### key\_revoke key_revoke($id) Revokes access to the key with given id. No operations other than `unlink` are possible on revoked keys. Corresponds to `keyctl revoke ` shell command from keyutils package # REPOSITORY []( # AUTHOR Viktor Liu # COPYRIGHT AND LICENSING 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.