Koha/Token.pm

   1 package Koha::Token;
   2
   3 # Created as wrapper for CSRF tokens, but designed for more general use
   4
   5 # Copyright 2016 Rijksmuseum
   6 #
   7 # This file is part of Koha.
   8 #
   9 # Koha is free software; you can redistribute it and/or modify it under the
  10 # terms of the GNU General Public License as published by the Free Software
  11 # Foundation; either version 3 of the License, or (at your option) any later
  12 # version.
  13 #
  14 # Koha is distributed in the hope that it will be useful, but WITHOUT ANY
  15 # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  16 # A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  17 #
  18 # You should have received a copy of the GNU General Public License along
  19 # with Koha; if not, write to the Free Software Foundation, Inc.,
  20 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21
  22 =head1 NAME
  23
  24 Koha::Token - Tokenizer
  25
  26 =head1 SYNOPSIS
  27
  28     use Koha::Token;
  29     my $tokenizer = Koha::Token->new;
  30     my $token = $tokenizer->generate({ length => 20 });
  31
  32     # safely generate a CSRF token (nonblocking)
  33     my $csrf_token = $tokenizer->generate({
  34         type => 'CSRF', id => $id, secret => $secret,
  35     });
  36
  37     # generate/check CSRF token with defaults and session id
  38     my $csrf_token = $tokenizer->generate_csrf({ session_id => $x });
  39     my $result = $tokenizer->check_csrf({
  40         session_id => $x, token => $token,
  41     });
  42
  43 =head1 DESCRIPTION
  44
  45     Designed for providing general tokens.
  46     Created due to the need for a nonblocking call to Bytes::Random::Secure
  47     when generating a CSRF token.
  48
  49 =cut
  50
  51 use Modern::Perl;
  52 use Bytes::Random::Secure ();
  53 use String::Random ();
  54 use WWW::CSRF ();
  55 use Digest::MD5 qw(md5_base64);
  56 use Encode qw( encode );
  57 use base qw(Class::Accessor);
  58 use constant HMAC_SHA1_LENGTH => 20;
  59 use constant CSRF_EXPIRY_HOURS => 8; # 8 hours instead of 7 days..
  60
  61 =head1 METHODS
  62
  63 =head2 new
  64
  65     Create object (via Class::Accessor).
  66
  67 =cut
  68
  69 sub new {
  70     my ( $class ) = @_;
  71     return $class->SUPER::new();
  72 }
  73
  74 =head2 generate
  75
  76     my $token = $tokenizer->generate({ length => 20 });
  77     my $csrf_token = $tokenizer->generate({
  78         type => 'CSRF', id => $id, secret => $secret,
  79     });
  80
  81     Generate several types of tokens. Now includes CSRF.
  82     Room for future extension.
  83
  84 =cut
  85
  86 sub generate {
  87     my ( $self, $params ) = @_;
  88     if( $params->{type} && $params->{type} eq 'CSRF' ) {
  89         $self->{lasttoken} = _gen_csrf( $params );
  90     } else {
  91         $self->{lasttoken} = _gen_rand( $params );
  92     }
  93     return $self->{lasttoken};
  94 }
  95
  96 =head2 generate_csrf
  97
  98     Like: generate({ type => 'CSRF', ... })
  99     Note: id defaults to userid from context, secret to database password.
 100     session_id is mandatory; it is combined with id.
 101
 102 =cut
 103
 104 sub generate_csrf {
 105     my ( $self, $params ) = @_;
 106     return if !$params->{session_id};
 107     $params = _add_default_csrf_params( $params );
 108     return $self->generate({ %$params, type => 'CSRF' });
 109 }
 110
 111 =head2 check
 112
 113     my $result = $tokenizer->check({
 114         type => 'CSRF', id => $id, token => $token,
 115     });
 116
 117     Check several types of tokens. Now includes CSRF.
 118     Room for future extension.
 119
 120 =cut
 121
 122 sub check {
 123     my ( $self, $params ) = @_;
 124     if( $params->{type} && $params->{type} eq 'CSRF' ) {
 125         return _chk_csrf( $params );
 126     }
 127     return;
 128 }
 129
 130 =head2 check_csrf
 131
 132     Like: check({ type => 'CSRF', ... })
 133     Note: id defaults to userid from context, secret to database password.
 134     session_id is mandatory; it is combined with id.
 135
 136 =cut
 137
 138 sub check_csrf {
 139     my ( $self, $params ) = @_;
 140     return if !$params->{session_id};
 141     $params = _add_default_csrf_params( $params );
 142     return $self->check({ %$params, type => 'CSRF' });
 143 }
 144
 145 # --- Internal routines ---
 146
 147 sub _add_default_csrf_params {
 148     my ( $params ) = @_;
 149     $params->{session_id} //= '';
 150     if( !$params->{id} ) {
 151         $params->{id} = Encode::encode( 'UTF-8', C4::Context->userenv->{id} . $params->{session_id} );
 152     } else {
 153         $params->{id} .= $params->{session_id};
 154     }
 155     $params->{id} //= Encode::encode( 'UTF-8', C4::Context->userenv->{id} );
 156     my $pw = C4::Context->config('pass');
 157     $params->{secret} //= md5_base64( Encode::encode( 'UTF-8', $pw ) ),
 158     return $params;
 159 }
 160
 161 sub _gen_csrf {
 162
 163 # Since WWW::CSRF::generate_csrf_token does not use the NonBlocking
 164 # parameter of Bytes::Random::Secure, we are passing random bytes from
 165 # a non blocking source to WWW::CSRF via its Random parameter.
 166
 167     my ( $params ) = @_;
 168     return if !$params->{id} || !$params->{secret};
 169
 170
 171     my $randomizer = Bytes::Random::Secure->new( NonBlocking => 1 );
 172         # this is most fundamental: do not use /dev/random since it is
 173         # blocking, but use /dev/urandom !
 174     my $random = $randomizer->bytes( HMAC_SHA1_LENGTH );
 175     my $token = WWW::CSRF::generate_csrf_token(
 176         $params->{id}, $params->{secret}, { Random => $random },
 177     );
 178
 179     return $token;
 180 }
 181
 182 sub _chk_csrf {
 183     my ( $params ) = @_;
 184     return if !$params->{id} || !$params->{secret} || !$params->{token};
 185
 186     my $csrf_status = WWW::CSRF::check_csrf_token(
 187         $params->{id},
 188         $params->{secret},
 189         $params->{token},
 190         { MaxAge => $params->{MaxAge} // ( CSRF_EXPIRY_HOURS * 3600 ) },
 191     );
 192     return $csrf_status == WWW::CSRF::CSRF_OK();
 193 }
 194
 195 sub _gen_rand {
 196     my ( $params ) = @_;
 197     my $length = $params->{length} || 1;
 198     $length = 1 unless $length > 0;
 199
 200     return String::Random::random_string( '.' x $length );
 201 }
 202
 203 =head1 AUTHOR
 204
 205     Marcel de Rooy, Rijksmuseum Amsterdam, The Netherlands
 206
 207 =cut
 208
 209 1;