qpsmtpd/plugins/whitelist
2012-11-14 15:24:06 -05:00

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=head1 NAME
whitelist - whitelist override for other qpsmtpd plugins
=head1 DESCRIPTION
The B<whitelist> plugin allows selected hosts or senders or recipients
to be whitelisted as exceptions to later plugin processing. It is a more
conservative variant of Devin Carraway's 'whitelist' plugin.
=head1 CONFIGURATION
To enable the plugin, add it to the qpsmtpd/config/plugins file as usual.
It should precede any plugins you might wish to whitelist for.
Several configuration files are supported, corresponding to different
parts of the SMTP conversation:
=over 4
=item whitelisthosts
Any IP address (or start-anchored fragment thereof) listed in the
whitelisthosts file is exempted from any further validation during
'connect', and can be selectively exempted at other stages by
plugins testing for a 'whitelisthost' connection note.
Similarly, if the environment variable $WHITELISTCLIENT is set
(which can be done by tcpserver), the connection will be exempt from
further 'connect' validation, and the host can be selectively
exempted by other plugins testing for a 'whitelistclient' connection
note.
=item whitelisthelo
Any host that issues a HELO matching an entry in whitelisthelo will
be exempted from further validation at the 'helo' stage. Subsequent
plugins can test for a 'whitelisthelo' connection note. Note that
this does not actually amount to an authentication in any meaningful
sense.
=item whitelistsenders
If the envelope sender of a mail (that which is sent as the MAIL FROM)
matches an entry in whitelistsenders, or if the hostname component
matches, the mail will be exempted from any further validation within
the 'mail' stage. Subsequent plugins can test for this exemption as a
'whitelistsender' transaction note.
=item whitelistrcpt
If any recipient of a mail (that sent as the RCPT TO) matches an
entry from whitelistrcpt, or if the hostname component matches, no
further validation will be required for this recipient. Subsequent
plugins can test for this exemption using a 'whitelistrcpt'
transaction note, which holds the count of whitelisted recipients.
=back
whitelist_soft also supports per-recipient whitelisting when using
the per_user_config plugin. To enable the per-recipient behaviour
(delaying all whitelisting until the rcpt part of the smtp
conversation, and using per-recipient whitelist configs, if
available), pass a true 'per_recipient' argument in the
config/plugins invocation i.e.
whitelist_soft per_recipient 1
By default global and per-recipient whitelists are merged; to turn off
the merge behaviour pass a false 'merge' argument in the config/plugins
invocation i.e.
whitelist_soft per_recipient 1 merge 0
=head1 BUGS
Whitelist lookups are all O(n) linear scans of configuration files, even
though they're all associative lookups. Something should be done about
this when CDB/DB/GDBM configs are supported.
=head1 AUTHOR
Based on the 'whitelist' plugin by Devin Carraway <qpsmtpd@devin.com>.
Modified by Gavin Carr <gavin@openfusion.com.au> to not inherit
whitelisting across hooks, but use per-hook whitelist notes instead.
This is a more conservative approach e.g. whitelisting an IP will not
automatically allow relaying from that IP.
=cut
use strict;
use warnings;
use lib 'lib';
use Qpsmtpd::Constants;
my $VERSION = 0.02;
# Default is to merge whitelists in per_recipient mode
my %MERGE = (merge => 1);
sub register {
my ($self, $qp, %arg) = @_;
$self->{_per_recipient} = 1 if $arg{per_recipient};
$MERGE{merge} = $arg{merge} if defined $arg{merge};
# Normal mode - whitelist per hook
unless ($arg{per_recipient}) {
$self->register_hook("connect", "check_host");
$self->register_hook("helo", "check_helo");
$self->register_hook("ehlo", "check_helo");
$self->register_hook("mail", "check_sender");
$self->register_hook("rcpt", "check_rcpt");
}
# Per recipient mode - defer all whitelisting to rcpt hook
else {
$self->register_hook("rcpt", "check_host");
$self->register_hook("helo", "helo_helper");
$self->register_hook("ehlo", "helo_helper");
$self->register_hook("rcpt", "check_helo");
$self->register_hook("rcpt", "check_sender");
$self->register_hook("rcpt", "check_rcpt");
}
}
sub check_host {
my ($self, $transaction, $rcpt) = @_;
my $ip = $self->qp->connection->remote_ip || return (DECLINED);
# From tcpserver
if (exists $ENV{WHITELISTCLIENT}) {
$self->qp->connection->notes('whitelistclient', 1);
$self->log(2, "host $ip is a whitelisted client");
return OK;
}
my $config_arg = $self->{_per_recipient} ? {rcpt => $rcpt, %MERGE} : {};
for my $h ($self->qp->config('whitelisthosts', $config_arg)) {
if ($h eq $ip or $ip =~ /^\Q$h\E/) {
$self->qp->connection->notes('whitelisthost', 1);
$self->log(2, "host $ip is a whitelisted host");
return OK;
}
}
$self->log(LOGDEBUG, "skip: $ip is not whitelisted");
return DECLINED;
}
sub helo_helper {
my ($self, $transaction, $helo) = @_;
$self->{_whitelist_soft_helo} = $helo;
return DECLINED;
}
sub check_helo {
my ($self, $transaction, $helo) = @_;
# If per_recipient will be rcpt hook, and helo actually rcpt
my $config_arg = {};
if ($self->{_per_recipient}) {
$config_arg = {rcpt => $helo, %MERGE};
$helo = $self->{_whitelist_soft_helo};
}
for my $h ($self->qp->config('whitelisthelo', $config_arg)) {
if ($helo and lc $h eq lc $helo) {
$self->qp->connection->notes('whitelisthelo', 1);
$self->log(2, "helo host $helo in whitelisthelo");
return OK;
}
}
return DECLINED;
}
sub check_sender {
my ($self, $transaction, $sender) = @_;
# If per_recipient will be rcpt hook, and sender actually rcpt
my $config_arg = {};
if ($self->{_per_recipient}) {
$config_arg = {rcpt => $sender, %MERGE};
$sender = $transaction->sender;
}
return DECLINED if $sender->format eq '<>';
my $addr = lc $sender->address or return DECLINED;
my $host = lc $sender->host or return DECLINED;
for my $h ($self->qp->config('whitelistsenders', $config_arg)) {
next unless $h;
$h = lc $h;
if ($addr eq $h or $host eq $h) {
$transaction->notes('whitelistsender', 1);
$self->log(2, "envelope sender $addr in whitelistsenders");
return OK;
}
}
return DECLINED;
}
sub check_rcpt {
my ($self, $transaction, $rcpt) = @_;
my $addr = lc $rcpt->address or return DECLINED;
my $host = lc $rcpt->host or return DECLINED;
my $config_arg = $self->{_per_recipient} ? {rcpt => $rcpt, %MERGE} : {};
for my $h ($self->qp->config('whitelistrcpt', $config_arg)) {
next unless $h;
$h = lc $h;
if ($addr eq $h or $host eq $h) {
my $note = $transaction->notes('whitelistrcpt');
$transaction->notes('whitelistrcpt', ++$note);
$self->log(2, "recipient $addr in whitelistrcpt");
return OK;
}
}
return DECLINED;
}