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From fbbf43ad15c1025d9f1e0a2259371ff1533504cd Mon Sep 17 00:00:00 2001 |
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From: Matt Simerson <matt@tnpi.net> |
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Date: Mon, 10 May 2010 19:07:48 -0400 |
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Subject: added auth_checkpassword plugin |
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New and improved! |
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With POD! (because JP said so: http://www.nntp.perl.org/group/perl.qpsmtpd/2005/06/msg3145.html) |
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Includes usage notes and a perl script useful for diagnosing a checkpassword program. |
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Signed-off-by: Robert <rspier@pobox.com> |
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--- |
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MANIFEST | 1 + |
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plugins/auth/auth_checkpassword | 145 +++++++++++++++++++++++++++++++++++++++ |
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2 files changed, 146 insertions(+), 0 deletions(-) |
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create mode 100644 plugins/auth/auth_checkpassword |
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diff --git a/MANIFEST b/MANIFEST |
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index 930ddbf..9d5912a 100644 |
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--- a/MANIFEST |
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+++ b/MANIFEST |
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@@ -62,6 +62,7 @@ plugins/async/queue/smtp-forward |
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plugins/async/require_resolvable_fromhost |
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plugins/async/rhsbl |
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plugins/async/uribl |
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+plugins/auth/auth_checkpassword |
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plugins/auth/auth_cvm_unix_local |
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plugins/auth/auth_flat_file |
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plugins/auth/auth_ldap_bind |
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diff --git a/plugins/auth/auth_checkpassword b/plugins/auth/auth_checkpassword |
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new file mode 100644 |
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index 0000000..6337ff7 |
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--- /dev/null |
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+++ b/plugins/auth/auth_checkpassword |
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@@ -0,0 +1,145 @@ |
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+#!/usr/bin/perl -w |
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+ |
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+=head1 NAME |
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+ |
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+auth_checkpassword - Authenticate against a DJB style checkpassword program |
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+ |
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+=head1 DESCRIPTION |
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+ |
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+This plugin authenticates users against a DJB style checkpassword |
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+program. Unlike previous checkpassword implementations, this plugin |
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+expects qpsmtpd to be running as the qpsmtpd user. Privilege |
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+escalation can be attained by running the checkpassword binary setuid |
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+or with sudo. |
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+ |
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+=head1 CONFIGURATION |
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+ |
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+Configure the path to your checkpassword binary: |
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+ |
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+ echo "/usr/local/vpopmail/bin/vchkpw /usr/bin/true" > ~qpsmtpd/config/smtpauth-checkpassword |
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+ |
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+vchkpw is the checkpassword program provided by vpopmail. Substitute |
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+your own checkpassword app as appropriate. |
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+ |
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+If you are using vchkpw and this plugin is being executed by a user ID |
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+other than 89 or 0 (as is the default), and the vchkpw binary is not |
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+setuid (as is the default), this plugin will automatically prepend the |
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+vchkpw command with sudo. If that is the case, you must configure sudo |
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+by adding these two lines to your sudoers file: |
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+ |
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+ Defaults:qpsmtpd closefrom_override |
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+ qpsmtpd ALL = (ALL) NOPASSWD: /usr/local/vpopmail/bin/vchkpw |
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+ |
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+The closefrom_override option is necessary because, by default, sudo |
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+appropriates the first 3 file descriptors. Those descriptors are |
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+necessary to communicate with the checkpassword program. If you run |
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+qpsmtpd as some other user, adjust the sudo lines approriately. |
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+ |
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+Using sudo is preferable to enabling setuid on the vchkpw binary. If |
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+you reinstall vpopmail and the setuid bit is lost, this plugin will be |
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+broken. |
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+ |
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+=head1 DIAGNOSTICS |
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+ |
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+Is the path in the config/smtpauth-checkpassword correct? |
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+ |
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+Is the path to true in config/smtpauth-checkpassword correct? |
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+ |
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+Is qpsmtpd running as the qpsmtpd user? If not, did you adjust the |
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+sudo configuration appropriately? |
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+ |
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+If you are not using sudo, did you remember to make the vchkpw binary |
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+setuid (chmod 4711 ~vpopmail/bin/vchkpw)? |
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+ |
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+While writing this plugin, I first wrote myself a little test script, |
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+which helped me identify the sudo closefrom_override issue. Here is |
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+that script: |
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+ |
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+ #!/usr/bin/perl |
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+ use strict; |
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+ my $sudo = "/usr/local/bin/sudo"; |
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+ $sudo .= " -C4 -u vpopmail"; |
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+ my $vchkpw = "/usr/local/vpopmail/bin/vchkpw"; |
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+ my $true = "/usr/bin/true"; |
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+ |
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+ open(CPW,"|$sudo $vchkpw $true 3<&0"); |
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+ printf(CPW "%s\0%s\0Y123456\0",'user@example.com','pa55word'); |
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+ close(CPW); |
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+ |
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+ my $status = $?; |
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+ print "FAIL\n" and exit if ( $status != 0 ); |
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+ print "OK\n"; |
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+ |
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+Save that script to vchkpw.pl and then run it as the same user that |
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+qpsmtpd runs as: |
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+ |
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+ setuidgid qpsmtpd perl vchkpw.pl |
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+ |
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+If you aren't using sudo, then remove $sudo from the open line. |
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+ |
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+=head1 ACKNOWLEDGEMENTS |
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+ |
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+based upon authcheckpassword by Michael Holzt |
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+and adapted by Johan Almqvist 2006-01-18 |
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+ |
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+=head1 AUTHOR |
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+ |
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+Matt Simerson <msimerson@cpan.org> |
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+ |
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+=head1 COPYRIGHT AND LICENSE |
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+ |
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+Copyright (c) 2010 Matt Simerson |
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+ |
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+This plugin is licensed under the same terms as the qpsmtpd package itself. |
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+Please see the LICENSE file included with qpsmtpd for details. |
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+ |
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+=cut |
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+ |
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+sub register { |
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+ my ($self, $qp) = @_; |
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+ |
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+ $self->register_hook("auth-plain", "auth_checkpassword"); |
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+ $self->register_hook("auth-login", "auth_checkpassword"); |
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+} |
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+ |
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+sub auth_checkpassword { |
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+ my ($self, $transaction, $method, $user, $passClear, $passHash, $ticket) = |
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+ @_; |
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+ |
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+ my $command = $self->qp->config("smtpauth-checkpassword") |
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+ or return (DECLINED); |
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+ my ($binary, $params) = $command =~ /^(\S+)(.*)$/; |
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+ |
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+ return (DECLINED) if (!-x $binary); |
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+ my $sudo = get_sudo($binary); |
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+ |
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+ open(CPW, "|$sudo $binary $params 3<&0"); |
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+ printf(CPW "%s\0%s\0Y123456\0", $user, $passClear); |
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+ close(CPW); |
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+ |
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+ my $status = $?; |
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+ |
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+ return (DECLINED) if ($status != 0); |
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+ |
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+ $self->connection->notes('authuser', $user); |
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+ return (OK, "auth_checkpassword"); |
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+} |
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+ |
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+sub get_sudo { |
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+ my $binary = shift; |
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+ |
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+ return '' if $> == 0; # running as root |
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+ return '' if $> == 89 && $binary =~ /vchkpw/; # running as vpopmail |
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+ |
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+ my $mode = (stat($binary))[2]; |
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+ $mode = sprintf "%lo", $mode & 07777; |
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+ return '' if $mode eq '4711'; # $binary is setuid |
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+ |
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+ my $sudo = `which sudo` || '/usr/local/bin/sudo'; |
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+ return '' if !-x $sudo; |
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+ $sudo .= ' -C4'; # prevent sudo from clobber file descriptor 3 |
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+ |
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+ return "$sudo -u vpopmail" if $binary =~ /vchkpw/; |
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+ return $sudo; |
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+} |
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+ |
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-- |
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1.7.2.2 |
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