231 lines
7.1 KiB
Perl
231 lines
7.1 KiB
Perl
#!/usr/bin/perl -w
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# $Id$
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=head1 NAME
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clamdscan
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=head1 DESCRIPTION
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A qpsmtpd plugin for virus scanning using the ClamAV scan daemon, clamd.
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=head1 RESTRICTIONS
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The ClamAV scan daemon, clamd, must have at least execute access to the qpsmtpd
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spool directory in order to sucessfully scan the messages. You can ensure this
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by running clamd as the same user as qpsmtpd does, or by doing the following:
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=over 4
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=item * Change the group ownership of the spool directory to be a group
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of which clamav is a member or add clamav to the same group as the qpsmtpd
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user.
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=item * Enable the "AllowSupplementaryGroups" option in clamd.conf.
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=item * Add group-execute permissions to the qpsmtpd spool directory.
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=item * Make sure that all directories above the spool directory (to the
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root) are g+x so that the group has directory traversal rights; it is not
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necessary for the group to have any read rights.
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=back
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It may be helpful to temporary grant the clamav user a shell and test to
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make sure you can cd into the spool directory and read files located there.
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Remember to remove the shell from the clamav user when you are done
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testing.
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=head1 INSTALL AND CONFIG
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Place this plugin in the plugin/virus directory beneath the standard
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qpsmtpd installation. If you installed clamd with the default path, you
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can use this plugin with default options (nothing specified):
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You must have the ClamAV::Client module installed to use the plugin.
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=over 4
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=item B<clamd_socket>
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Full path to the clamd socket (the recommended mode), if different from the
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ClamAV::Client defaults.
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=item B<clamd_port>
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If present, must be the TCP port where the clamd service is running,
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typically 3310; default disabled. If present, overrides the clamd_socket.
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=item B<deny_viruses>
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Whether the scanner will automatically delete messages which have viruses.
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Takes either 'yes' or 'no' (defaults to 'yes'). If set to 'no' it will add
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a header to the message with the virus results.
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=item B<defer_on_error>
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Whether to defer the mail (with a soft-failure error, which will incur a retry)
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if an unrecoverable error occurs during the scan. The default is to accept
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the mail under these conditions. This can permit viruses to be accepted when
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the clamd daemon is malfunctioning or unreadable, but will not allow mail to
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backlog or be lost if the condition persists.
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=item B<max_size>
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The maximum size, in kilobytes, of messages to scan; defaults to 128k.
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=item B<scan_all>
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Scan all messages, even if there are no attachments
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=back
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=head1 REQUIREMENTS
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This module requires the ClamAV::Client module, found on CPAN here:
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L<http://search.cpan.org/dist/ClamAV-Client/>
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=head1 AUTHOR
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Originally written for the Clamd module by John Peacock <jpeacock@cpan.org>;
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adjusted for ClamAV::Client by Devin Carraway <qpsmtpd/@/devin.com>.
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=head1 COPYRIGHT AND LICENSE
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Copyright (c) 2005 John Peacock,
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Copyright (c) 2007 Devin Carraway
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Based heavily on the clamav plugin
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This plugin is licensed under the same terms as the qpsmtpd package itself.
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Please see the LICENSE file included with qpsmtpd for details.
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=cut
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use ClamAV::Client;
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use strict;
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use warnings;
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sub register {
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my ( $self, $qp, @args ) = @_;
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%{ $self->{"_clamd"} } = @args;
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# Set some sensible defaults
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$self->{"_clamd"}->{"deny_viruses"} ||= "yes";
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$self->{"_clamd"}->{"max_size"} ||= 128;
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$self->{"_clamd"}->{"scan_all"} ||= 0;
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for my $setting ('deny_viruses', 'defer_on_error') {
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next unless $self->{"_clamd"}->{$setting};
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$self->{"_clamd"}->{$setting} = 0
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if lc $self->{"_clamd"}->{$setting} eq 'no';
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}
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}
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sub hook_data_post {
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my ( $self, $transaction ) = @_;
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$DB::single = 1;
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if ( $transaction->data_size > $self->{"_clamd"}->{"max_size"} * 1024 ) {
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$self->log( LOGNOTICE, "Declining due to data_size" );
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return (DECLINED);
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}
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# Ignore non-multipart emails
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my $content_type = $transaction->header->get('Content-Type');
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$content_type =~ s/\s/ /g if defined $content_type;
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unless ( $self->{"_clamd"}->{"scan_all"}
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|| $content_type
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&& $content_type =~ m!\bmultipart/.*\bboundary="?([^"]+)!i )
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{
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$self->log( LOGNOTICE, "non-multipart mail - skipping" );
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return DECLINED;
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}
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my $filename = $transaction->body_filename;
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unless ($filename) {
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$self->log( LOGWARN, "Cannot process due to lack of filename" );
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return (DECLINED); # unless $filename;
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}
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# the spool directory must be readable and executable by the scanner;
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# this generally means either group or world exec; if
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# neither of these is set, issue a warning but try to proceed anyway
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my $mode = ( stat( $self->spool_dir() ) )[2];
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if ( $mode & 0010 || $mode & 0001 ) {
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# match the spool file mode with the mode of the directory -- add
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# the read bit for group, world, or both, depending on what the
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# spool dir had, and strip all other bits, especially the sticky bit
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my $fmode = ($mode & 0044) |
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($mode & 0010 ? 0040 : 0) |
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($mode & 0001 ? 0004 : 0);
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unless ( chmod $fmode, $filename ) {
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$self->log( LOGERROR, "chmod: $filename: $!" );
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return DECLINED;
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}
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} else {
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$self->log( LOGWARN,
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"Permission on spool directory do not permit scanner access" );
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}
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my $clamd;
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if ( ($self->{"_clamd"}->{"clamd_port"} || '') =~ /^(\d+)/ ) {
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$clamd = new ClamAV::Client( socket_host =>
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$self->{_clamd}->{clamd_host},
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socket_port => $1 );
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}
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elsif ( ($self->{"_clamd"}->{"clamd_socket"} || '') =~ /([\w\/.]+)/ ) {
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$clamd = new ClamAV::Client( socket_name => $1 );
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}
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else {
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$clamd = new ClamAV::Client;
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}
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unless ( $clamd ) {
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$self->log( LOGERROR, "Cannot instantiate ClamAV::Client" );
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return (DENYSOFT, "Unable to scan for viruses")
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if $self->{"_clamd"}->{"defer_on_error"};
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return DECLINED;
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}
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unless ( eval { $clamd->ping() } ) {
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$self->log( LOGERROR, "Cannot ping clamd server: $@" );
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return (DENYSOFT, "Unable to scan for viruses")
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if $self->{"_clamd"}->{"defer_on_error"};
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return DECLINED;
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}
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my ( $path, $found ) = eval { $clamd->scan_path( $filename ) };
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if ($@) {
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$self->log( LOGERROR, "Error scanning mail: $@" );
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return (DENYSOFT, "Unable to scan for viruses")
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if $self->{"_clamd"}->{"defer_on_error"};
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return DECLINED;
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}
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elsif ( $found ) {
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$self->log( LOGERROR, "Virus found: $found" );
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if ( $self->{"_clamd"}->{"deny_viruses"} ) {
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return ( DENY, "Virus found: $found" );
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}
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else {
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$transaction->header->add( 'X-Virus-Found', 'Yes' );
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$transaction->header->add( 'X-Virus-Details', $found );
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return (DECLINED);
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}
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}
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else {
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$self->log( LOGINFO, "ClamAV scan reports clean");
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}
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$transaction->header->add( 'X-Virus-Checked',
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"Checked by ClamAV on " . $self->qp->config("me") );
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return (DECLINED);
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}
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# vi: set ts=4 sw=4 et:
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