From d82ad3bf32fca62216ac86250b795d167eff02ca Mon Sep 17 00:00:00 2001
From: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>
Date: Wed, 11 Sep 2024 20:27:04 +0200
Subject: [PATCH] Initial code

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>
---
 authorized-exec.pl | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100755 authorized-exec.pl

diff --git a/authorized-exec.pl b/authorized-exec.pl
new file mode 100755
index 0000000..0cf71b0
--- /dev/null
+++ b/authorized-exec.pl
@@ -0,0 +1,50 @@
+#!/usr/bin/perl -W
+# Wrapper to be used as a forced SSH command.
+#
+# Copyright 2024, Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>
+#
+# Licensed under the EUPL, Version 1.2 or - as soon they will be approved by the European Commission - subsequent versions of the EUPL (the "Licence").
+# You may not use this work except in compliance with the Licence.
+# An English copy of the Licence is shipped in a file called LICENSE along with this applications source code.
+# You may obtain copies of the Licence in any of the official languages at https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12.
+
+use v5.26;	# Leap 15.6
+
+use List::Util 'any';
+
+die "Usage: $0 <config> <command line>" unless @ARGV;
+
+my $configfile = shift @ARGV;
+	die "File $configfile does not exist" unless -f $configfile;
+
+my %config = do $configfile;
+	die "Couldn't parse $configfile: $@" if $@;
+	die "Couldn't run $configfile"       unless %config;
+
+my $user = $ENV{'USER'};
+
+if (! exists($config{$user}) ) {
+	print STDERR 'Unauthorized user.';
+	exit 1
+}
+
+my $cmd;
+my $ssh_cmd = $ENV{'SSH_ORIGINAL_COMMAND'};
+
+if ($ssh_cmd) {
+	$cmd = $ssh_cmd;
+} elsif (@ARGV) {
+	$cmd = qq{@ARGV};
+} else {
+	print STDERR 'Missing command.';
+	exit 1
+}
+
+my %cmds = map { qr{$_} => 1 } @{$config{$user}};
+
+if ( any { $cmd =~ $_ } keys %cmds ) {
+	exec $cmd;
+} else {
+	print STDERR 'Execution denied.';
+	exit 1
+}