feat: add support for Duo PAM auth as MFA (#249)

bin/helper/osh-accountMFAResetTOTP

@@ -77,15 +77,31 @@ if (OVH::Bastion::is_admin(account => $account, sudo => 1) && !OVH::Bastion::is_
     HEXIT('ERR_SECURITY_VIOLATION', msg => "You can't reset the TOTP of an admin without being admin yourself");
 }
 
+my $TOTPProvider = OVH::Bastion::config("TOTPProvider")->value;
+if ($TOTPProvider eq 'none') {
+    HEXIT('ERR_CONFIGURATION_ERROR', msg => "TOTP Provider has not been set, please report to your sysadmin");
+}
+elsif ($TOTPProvider eq 'google-authenticator') {
+
+    # for google-authenticator, attempt remove the .otp file (non-fatal)
+    if (!unlink($home . '/' . OVH::Bastion::TOTP_GAUTH_FILENAME)) {
+        warn_syslog("Couldn't remove the TOTP file ($!), this is not fatal, continuing anyway");
+    }
+}
+elsif ($TOTPProvider eq 'duo') {
+
+    # duo doesn't need any user-specific local cleanup
+}
+else {
+    # unknown provider, this shouldn't happen
+    HEXIT('ERR_CONFIGURATION_ERROR', msg => "An unknown TOTP provider has been provided, please check with your sysadmin.");
+}
+
+# remove the user from the TOTP configured group
 if (OVH::Bastion::is_user_in_group(user => $account, group => OVH::Bastion::MFA_TOTP_CONFIGURED_GROUP)) {
     $fnret = OVH::Bastion::sys_delmemberfromgroup(user => $account, group => OVH::Bastion::MFA_TOTP_CONFIGURED_GROUP);
     $fnret or HEXIT($fnret);
 }
 
-# remove the .otp file (non-fatal)
-if (!unlink($home . '/' . OVH::Bastion::TOTP_FILENAME)) {
-    osh_warn("Couldn't remove the TOTP file ($!), this is not fatal, continuing anyway");
-}
-
 osh_info "TOTP has been reset, " . ($account eq $self ? 'you' : $account) . " can re-enroll by using the `--osh selfMFASetupTOTP' command, if applicable";
 HEXIT('OK');

bin/plugin/open/selfMFASetupTOTP

@@ -37,39 +37,53 @@ if ($ENV{'OSH_IN_INTERACTIVE_SESSION'}) {
 
 # do the TOTP enrollment
 
-# first, check if the google-authenticator we have supports --issuer, if not, just omit it, it's not a deal-breaker
-$fnret = OVH::Bastion::execute(cmd => ['google-authenticator', '-h'], must_succeed => 1);
-$fnret or HEXIT($fnret);
-my @additional_params;
-if (grep { /--issuer/ } @{$fnret->value->{'stdout'}}) {
-    push @additional_params, "--issuer=" . OVH::Bastion::config('bastionName')->value;
-}
-if ($noConfirm && grep { /--no-confirm/ } @{$fnret->value->{'stdout'}}) {
-    push @additional_params, "--no-confirm";
-}
+my $TOTPProvider = OVH::Bastion::config("TOTPProvider")->value;
 
-@command = (
-    'script', '-q', '-c', "google-authenticator -f -t -Q UTF8 -r 3 -R 15 -w 2 -D " . join(" ", @additional_params) . " -l $self -s $HOME/" . OVH::Bastion::TOTP_FILENAME,
-    '/dev/null'
-);
-{
-    local $ENV{'SHELL'} = '/bin/sh';
-    $fnret = OVH::Bastion::execute(cmd => \@command, noisy_stderr => 1, noisy_stdout => 1, expects_stdin => 1, is_binary => 1, must_succeed => 1);
+if ($TOTPProvider eq 'none') {
+
+    # unconfigured: as we don't know which provider we have, just error out
+    osh_exit(R('ERR_CONFIGURATION_ERROR', msg => "No TOTP provider has been enabled, please check with your sysadmin if this is unexpected"));
 }
-$fnret or osh_exit $fnret;
+elsif ($TOTPProvider eq 'google-authenticator') {
+
+    # first, check if the google-authenticator we have supports --issuer, if not, just omit it, it's not a deal-breaker
+    $fnret = OVH::Bastion::execute(cmd => ['google-authenticator', '-h'], must_succeed => 1);
+    $fnret or osh_exit($fnret);
+    my @additional_params;
+    if (grep { /--issuer/ } @{$fnret->value->{'stdout'}}) {
+        push @additional_params, "--issuer=" . OVH::Bastion::config('bastionName')->value;
+    }
+    if ($noConfirm && grep { /--no-confirm/ } @{$fnret->value->{'stdout'}}) {
+        push @additional_params, "--no-confirm";
+    }
 
-if (!$fnret) {
-    osh_exit('ERR_TOTP_SETUP_FAILED', msg => "Couldn't setup TOTP for your account, try again!");
+    @command = (
+        'script', '-q', '-c', "google-authenticator -f -t -Q UTF8 -r 3 -R 15 -w 2 -D " . join(" ", @additional_params) . " -l $self -s $HOME/" . OVH::Bastion::TOTP_GAUTH_FILENAME,
+        '/dev/null'
+    );
+    {
+        local $ENV{'SHELL'} = '/bin/sh';
+        $fnret = OVH::Bastion::execute(cmd => \@command, noisy_stderr => 1, noisy_stdout => 1, expects_stdin => 1, is_binary => 1, must_succeed => 1);
+    }
+
+    if (!$fnret) {
+        osh_exit('ERR_TOTP_SETUP_FAILED', msg => "Couldn't setup TOTP for your account, try again!");
+    }
+
+    chmod 0400, $HOME . '/' . OVH::Bastion::TOTP_GAUTH_FILENAME;
 }
+elsif ($TOTPProvider eq 'duo') {
 
-chmod 0400, $HOME . '/' . OVH::Bastion::TOTP_FILENAME;
+    # nothing to do locally, appart from marking the user as TOTP-active, which is done after this block.
+}
+else {
+    # unknown provider, this shouldn't happen
+    osh_exit(R('ERR_CONFIGURATION_ERROR', msg => "An unknown TOTP provider has been provided, please check with your sysadmin."));
+}
 
 # it worked, add the account to the proper system group
 @command = qw{ sudo -n -u root -- /usr/bin/env perl -T };
 push @command, $OVH::Bastion::BASEPATH . '/bin/helper/osh-selfMFASetupTOTP';
 push @command, '--account', $self;
 
-$fnret = OVH::Bastion::helper(cmd => \@command);
-$fnret or osh_exit $fnret;
-
-osh_exit $fnret;
+osh_exit(OVH::Bastion::helper(cmd => \@command));

etc/bastion/bastion.conf.dist

@@ -410,6 +410,14 @@
 # EXAMPLE: ["sudo","-n","-u","root","--","/sbin/pam_tally2","-u","%ACCOUNT%","-r"] or ["/usr/sbin/faillock","--reset"]
 "MFAPostCommand": [],
 #
+# TOTPProvider (string)
+#    DESC: Defines which is the provider of the TOTP MFA, that will be used for the ``(self|account)MFA(Setup|Reset)TOTP`` commands. Allowed values are:
+#          - none: no TOTP provider is defined, the corresponding setup commands won't be available.
+#          - google-authenticator: the pam_google_authenticator.so module will be used, along with its corresponding setup binary. This is the default, for backward compatibility reasons. This is also what is configured in the provided pam templates.
+#          - duo: enable the use of the Duo PAM module (pam_duo.so), of course you need to set it up correctly in your `/etc/pam.d/sshd` file.
+# DEFAULT: 'google-authenticator'
+"TOTPProvider": "google-authenticator",
+#
 #################
 # > Other options
 # >> These options are either discouraged (in which case this is explained in the description) or rarely need to be modified.

lib/perl/OVH/Bastion.pm

@@ -105,8 +105,8 @@ use constant {
     PAM_AUTH_BYPASS_GROUP          => 'bastion-nopam',
     OSH_PUBKEY_AUTH_OPTIONAL_GROUP => 'osh-pubkey-auth-optional',
 
-    TOTP_FILENAME => '.otp',
-    TOTP_BASEDIR  => '/var/otp',
+    TOTP_GAUTH_FILENAME => '.otp',
+    TOTP_BASEDIR        => '/var/otp',
 
     # authorized_keys file, relative to the user's HOME directory.
     # if you change this, also change it in lib/shell/functions.inc

lib/perl/OVH/Bastion/configuration.inc

@@ -286,8 +286,9 @@ sub load_configuration {
 
     # 4/6) Strings that must be one item of a specific enum.
     foreach my $o (
-        {name => 'defaultAccountEgressKeyAlgorithm', default => 'rsa',     valid => [qw{ rsa ecdsa ed25519 }]},
-        {name => 'accountMFAPolicy',                 default => 'enabled', valid => [qw{ disabled enabled password-required totp-required any-required }]},
+        {name => 'defaultAccountEgressKeyAlgorithm', default => 'rsa',                  valid => [qw{ rsa ecdsa ed25519 }]},
+        {name => 'accountMFAPolicy',                 default => 'enabled',              valid => [qw{ disabled enabled password-required totp-required any-required }]},
+        {name => 'TOTPProvider',                     default => 'google-authenticator', valid => [qw{ none google-authenticator duo }]},
       )
     {
         # if not defined, set to default value