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-1.0.1e.
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-7.4
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 > /bin/make-cert.pl << "EOF"
#!/usr/bin/perl -w
# Used to generate PEM encoded files from Mozilla certdata.txt.
# Run as ./mkcrt.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 $b eq '';
}
}
}
EOF
chmod +x /bin/make-cert.pl
The following script creates the certificates and a bundle of all
the certificates. It creates a ./certs
directory and ./BLFS-ca-bundle-${VERSION}.crt
. Again create
this script as the root
user:
cat > /bin/make-ca.sh << "EOF"
#!/bin/bash
# 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-${VERSION}.crt"
CONVERTSCRIPT="/bin/make-cert.pl"
SSLDIR="/etc/ssl"
mkdir "${TEMPDIR}/certs"
# Get a list of staring 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 certebegin certend
mkdir -p certs
rm 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 /bin/make-ca.sh
Add a short script to remove expired certificates from a directory.
Again create this script as the root
user:
cat > /bin/remove-expired-certs.sh << "EOF"
#!/bin/bash
# Begin /bin/remove-expired-certs.sh
#
# Version 20120211
# Make sure the date is parsed correctly on all systems
function 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 /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.
certhost='http://mxr.mozilla.org' &&
certdir='/mozilla/source/security/nss/lib/ckfw/builtins' &&
url="$certhost$certdir/certdata.txt?raw=1" &&
wget --output-document certdata.txt $url &&
unset certhost certdir url &&
make-ca.sh &&
remove-expired-certs.sh certs
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 -sv ../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
the section called “Install or update the JRE Certificate
Authority Certificates (cacerts) file”.