zabbix_agentd: Add helper script to get and verify certificate details

Add script to parse openssl output on certificates and return it as JSON for consumption by the Zabbix agent.
Reviewed-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/config/zabbix_agentd/ipfire_certificate_detail.sh b/config/zabbix_agentd/ipfire_certificate_detail.sh
new file mode 100755 (executable)
index 0000000..9ca0ef5
--- /dev/null
+++ b/config/zabbix_agentd/ipfire_certificate_detail.sh
@@ -0,0 +1,91 @@
+#!/bin/bash
+###############################################################################
+# ipfire_certificate_detail.sh - Get certificate details and validation results
+#                                in JSON format for use by Zabbix agent
+#
+# Author: robin.roevens (at) disroot.org
+# Version: 1.0
+#
+# Copyright (C) 2007-2024  IPFire Team  <info@ipfire.org> 
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License 
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# 
+###############################################################################
+
+# Required binaries
+OPENSSL=/usr/bin/openssl
+DATE=/bin/date
+
+# Parameter checking
+[[ $1 ]] || { echo "{\"error\":\"No CA certificate file given.\"}"; exit 1; }
+[[ -f $1 ]] || { echo "{\"error\":\"CA certificate not found: $1.\"}"; exit 1; }
+[[ -r $1 ]] || { echo "{\"error\":\"No read permission on CA certificate: $1.\"}"; exit 1; }
+[[ $2 ]] || { echo "{\"error\":\"No certificate file given.\"}"; exit 1; }
+[[ -f $2 ]] || { echo "{\"error\":\"Certificate not found: $2.\"}"; exit 1; }
+[[ -r $2 ]] || { echo "{\"error\":\"No read permission on certificate $2.\"}"; exit 1; }
+[[ -x $OPENSSL ]] || { echo "{\"error\":\"$OPENSSL binary not found or no permission.\"}"; exit 1; }
+[[ -x $DATE ]] || { echo "{\"error\":\"$DATE binary not found or no permission.\"}"; exit 1; }
+
+cafile=$1
+cert=$2
+
+# Parse certificate details
+cert_details=$(${OPENSSL} x509 -in "${cert}" -noout -text -certopt no_header,no_sigdump)
+version=$(echo "${cert_details}" | grep "Version:" | sed 's/^ \+Version: \([0-9]\+\) (.\+)$/\1/g')
+serial_number=$(echo "${cert_details}" | grep -A1 "Serial Number:" | tr -d '\n' | sed 's/^ \+Serial Number:\(\( \(.*\) ([0-9]\+x[0-9]\+).*\)\|\( \+\(.*\)$\)\)/\3\5/g')
+signature_algorithm=$(echo "${cert_details}" | grep "Signature Algorithm:" | sed 's/^ \+Signature Algorithm: //g')
+issuer=$(echo "${cert_details}" | grep "Issuer:" | sed 's/^ \+Issuer: //g' | sed 's/"/\\"/g')
+not_before_value=$(echo "${cert_details}" | grep "Not Before:" | sed 's/^ \+Not Before: //g')
+not_before_timestamp=$(${DATE} -d "${not_before_value}" +%s)
+not_after_value=$(echo "${cert_details}" | grep "Not After :" | sed 's/^ \+Not After : //g')
+not_after_timestamp=$(${DATE} -d "${not_after_value}" +%s)
+subject=$(echo "${cert_details}" | grep "Subject:" | sed 's/^ \+Subject: //g' | sed 's/"/\\"/g')
+public_key_algorithm=$(echo "${cert_details}" | grep "Public Key Algorithm:" | sed 's/^ \+Public Key Algorithm: //g')
+
+# Verify certificate
+cert_verify=$(${OPENSSL} verify -CAfile "${cafile}" "${cert}" 2>&1)
+if [[ $? != 0 ]]; then
+       result_value="invalid"
+       result_message="failed to verify certificate: x509: $(echo "${cert_verify}" | grep -E "error [0-9]+" | sed 's/^.\+: \(.\+\)/\1/g')"
+else
+       result_value="valid"
+       result_message="certificate verified successfully"
+fi
+
+# Generate fingerprints
+sha1_fingerprint=$(${OPENSSL} x509 -in "${cert}" -noout -fingerprint -sha1 | cut -d= -f2)
+sha256_fingerprint=$(${OPENSSL} x509 -in "${cert}" -noout -fingerprint -sha256 | cut -d= -f2)
+
+# Print certificate details in JSON
+echo -n "{\"x509\":{"
+echo -n "\"version\":\"${version}\","
+echo -n "\"serial_number\":\"${serial_number}\","
+echo -n "\"signature_algorithm\":\"${signature_algorithm}\","
+echo -n "\"issuer\":\"${issuer}\","
+echo -n "\"not_before\":{"
+echo -n "\"value\":\"${not_before_value}\","
+echo -n "\"timestamp\":\"${not_before_timestamp}\"},"
+echo -n "\"not_after\":{"
+echo -n "\"value\":\"${not_after_value}\","
+echo -n "\"timestamp\":\"${not_after_timestamp}\"},"
+echo -n "\"subject\":\"${subject}\","
+echo -n "\"public_key_algorithm\":\"${public_key_algorithm}\"},"
+echo -n "\"result\":{"
+echo -n "\"value\":\"${result_value}\","
+echo -n "\"message\":\"${result_message}\"},"
+echo -n "\"sha1_fingerprint\":\"${sha1_fingerprint}\","
+echo -n "\"sha256_fingerprint\":\"${sha256_fingerprint}\""
+echo -n "}"
+
+exit 0
\ No newline at end of file