The Public Key Inrastructure is used for many security issues in a
Linux system. In order for a certificate to be trusted, it must be
signed by a trusted agent called a Certificate Authority (CA). The
certificates loaded by this section are from the list on the Mozilla
version control system and formats it into a form used by OpenSSL-1.0.2.
The certificates can also be used by other applications either
directly of indirectly through openssl.
This package is known to build and work properly using an LFS-7.7
platform.
Installation of Certificate Authority Certificates
First create a script to reformat a certificate into a form needed
by openssl. As the root
user:
cat > /usr/bin/make-cert.pl << "EOF"
#!/usr/bin/perl -w
# Used to generate PEM encoded files from Mozilla certdata.txt.
# Run as ./make-cert.pl > certificate.crt
#
# Parts of this script courtesy of RedHat (mkcabundle.pl)
#
# This script modified for use with single file data (tempfile.cer) extracted
# from certdata.txt, taken from the latest version in the Mozilla NSS source.
# mozilla/security/nss/lib/ckfw/builtins/certdata.txt
#
# Authors: DJ Lucas
# Bruce Dubbs
#
# Version 20120211
my $certdata = './tempfile.cer';
open( IN, "cat $certdata|" )
|| die "could not open $certdata";
my $incert = 0;
while ( <IN> )
{
if ( /^CKA_VALUE MULTILINE_OCTAL/ )
{
$incert = 1;
open( OUT, "|openssl x509 -text -inform DER -fingerprint" )
|| die "could not pipe to openssl x509";
}
elsif ( /^END/ && $incert )
{
close( OUT );
$incert = 0;
print "\n\n";
}
elsif ($incert)
{
my @bs = split( /\\/ );
foreach my $b (@bs)
{
chomp $b;
printf( OUT "%c", oct($b) ) unless $b eq '';
}
}
}
EOF
chmod +x /usr/bin/make-cert.pl
The following script creates the certificates and a bundle of all
the certificates. It creates a ./certs
directory and ./BLFS-ca-bundle-${VERSION}.crt
. Again create
this script as the root
user:
cat > /usr/bin/make-ca.sh << "EOF"
#!/bin/sh
# Begin make-ca.sh
# Script to populate OpenSSL's CApath from a bundle of PEM formatted CAs
#
# The file certdata.txt must exist in the local directory
# Version number is obtained from the version of the data.
#
# Authors: DJ Lucas
# Bruce Dubbs
#
# Version 20120211
certdata="certdata.txt"
if [ ! -r $certdata ]; then
echo "$certdata must be in the local directory"
exit 1
fi
REVISION=$(grep CVS_ID $certdata | cut -f4 -d'$')
if [ -z "${REVISION}" ]; then
echo "$certfile has no 'Revision' in CVS_ID"
exit 1
fi
VERSION=$(echo $REVISION | cut -f2 -d" ")
TEMPDIR=$(mktemp -d)
TRUSTATTRIBUTES="CKA_TRUST_SERVER_AUTH"
BUNDLE="BLFS-ca-bundle-${VERSION}.crt"
CONVERTSCRIPT="/usr/bin/make-cert.pl"
SSLDIR="/etc/ssl"
mkdir "${TEMPDIR}/certs"
# Get a list of starting lines for each cert
CERTBEGINLIST=$(grep -n "^# Certificate" "${certdata}" | cut -d ":" -f1)
# Get a list of ending lines for each cert
CERTENDLIST=`grep -n "^CKA_TRUST_STEP_UP_APPROVED" "${certdata}" | cut -d ":" -f 1`
# Start a loop
for certbegin in ${CERTBEGINLIST}; do
for certend in ${CERTENDLIST}; do
if test "${certend}" -gt "${certbegin}"; then
break
fi
done
# Dump to a temp file with the name of the file as the beginning line number
sed -n "${certbegin},${certend}p" "${certdata}" > "${TEMPDIR}/certs/${certbegin}.tmp"
done
unset CERTBEGINLIST CERTDATA CERTENDLIST certbegin certend
mkdir -p certs
rm -f certs/* # Make sure the directory is clean
for tempfile in ${TEMPDIR}/certs/*.tmp; do
# Make sure that the cert is trusted...
grep "CKA_TRUST_SERVER_AUTH" "${tempfile}" | \
egrep "TRUST_UNKNOWN|NOT_TRUSTED" > /dev/null
if test "${?}" = "0"; then
# Throw a meaningful error and remove the file
cp "${tempfile}" tempfile.cer
perl ${CONVERTSCRIPT} > tempfile.crt
keyhash=$(openssl x509 -noout -in tempfile.crt -hash)
echo "Certificate ${keyhash} is not trusted! Removing..."
rm -f tempfile.cer tempfile.crt "${tempfile}"
continue
fi
# If execution made it to here in the loop, the temp cert is trusted
# Find the cert data and generate a cert file for it
cp "${tempfile}" tempfile.cer
perl ${CONVERTSCRIPT} > tempfile.crt
keyhash=$(openssl x509 -noout -in tempfile.crt -hash)
mv tempfile.crt "certs/${keyhash}.pem"
rm -f tempfile.cer "${tempfile}"
echo "Created ${keyhash}.pem"
done
# Remove blacklisted files
# MD5 Collision Proof of Concept CA
if test -f certs/8f111d69.pem; then
echo "Certificate 8f111d69 is not trusted! Removing..."
rm -f certs/8f111d69.pem
fi
# Finally, generate the bundle and clean up.
cat certs/*.pem > ${BUNDLE}
rm -r "${TEMPDIR}"
EOF
chmod +x /usr/bin/make-ca.sh
Add a short script to remove expired certificates from a directory.
Again create this script as the root
user:
cat > /usr/bin/remove-expired-certs.sh << "EOF"
#!/bin/sh
# Begin /usr/bin/remove-expired-certs.sh
#
# Version 20120211
# Make sure the date is parsed correctly on all systems
mydate()
{
local y=$( echo $1 | cut -d" " -f4 )
local M=$( echo $1 | cut -d" " -f1 )
local d=$( echo $1 | cut -d" " -f2 )
local m
if [ ${d} -lt 10 ]; then d="0${d}"; fi
case $M in
Jan) m="01";;
Feb) m="02";;
Mar) m="03";;
Apr) m="04";;
May) m="05";;
Jun) m="06";;
Jul) m="07";;
Aug) m="08";;
Sep) m="09";;
Oct) m="10";;
Nov) m="11";;
Dec) m="12";;
esac
certdate="${y}${m}${d}"
}
OPENSSL=/usr/bin/openssl
DIR=/etc/ssl/certs
if [ $# -gt 0 ]; then
DIR="$1"
fi
certs=$( find ${DIR} -type f -name "*.pem" -o -name "*.crt" )
today=$( date +%Y%m%d )
for cert in $certs; do
notafter=$( $OPENSSL x509 -enddate -in "${cert}" -noout )
date=$( echo ${notafter} | sed 's/^notAfter=//' )
mydate "$date"
if [ ${certdate} -lt ${today} ]; then
echo "${cert} expired on ${certdate}! Removing..."
rm -f "${cert}"
fi
done
EOF
chmod +x /usr/bin/remove-expired-certs.sh
The following commands will fetch the certificates and convert them
to the correct format. If desired, a web browser may be used
instead of wget but the file will
need to be saved with the name certdata.txt
. These commands can be repeated as
necessary to update the CA Certificates.
URL=http://anduin.linuxfromscratch.org/sources/other/certdata.txt &&
rm -f certdata.txt &&
wget $URL &&
make-ca.sh &&
remove-expired-certs.sh certs &&
unset URL
Now, as the root
user:
SSLDIR=/etc/ssl &&
install -d ${SSLDIR}/certs &&
cp -v certs/*.pem ${SSLDIR}/certs &&
c_rehash &&
install BLFS-ca-bundle*.crt ${SSLDIR}/ca-bundle.crt &&
ln -sfv ../ca-bundle.crt ${SSLDIR}/certs/ca-certificates.crt &&
unset SSLDIR
Finally, clean up the current directory:
rm -r certs BLFS-ca-bundle*
After installing or updating certificates, if OpenJDK is installed,
update the certificates for Java using the procedures at
JRE Certificate Authorithy Certificates.