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https://github.com/xcat2/confluent.git
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ed2a8b6f9d
It's imperfect, and abetter procedure should be written up for the more security conscious.
104 lines
4.2 KiB
Python
104 lines
4.2 KiB
Python
# This creates a locked down variant of a confluent CA
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# The confluent CA naturally doesn't have any name constraints, which
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# is great for flexibility.
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# However, if actually being imported into a web browser, it is likely
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# to want to limit the CA to apply to cluster resources rather
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# than having a blank check to vouch for any and all subjects.
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# This particular approach causes a certificate authority that
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# can be imported and vouch for the subset of certificates
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# that were issued by the normal CA that match name constraints
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# Unfortunately, *ALL* names are checked, whether they are relevant
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# to the conversation or not, so we reproduce the logic and the resultant
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# CA is fragile to IP addresses.
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# The better approach would be to issue a separate, full name only certificate
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# and have a simpler alt CA. The same CA can be used to sign both certificates,
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# and still import the limited one
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import subprocess
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import socket
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import confluent.certutil as certutil
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import sys
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def create_alt_ca(certout, permitdomains):
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# This is to create a constrained variant of the existing authority
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# this will allow a client browser to only trust it for select domains
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# while the nodes can more broadly trust it (e.g. to vouch for IP addresses)
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sslcfg = certutil.get_openssl_conf_location()
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newcfg = '/etc/confluent/tls/ca-alt/openssl-alt.cfg'
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subj = subprocess.check_output(
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['openssl', 'x509', '-subject', '-noout', '-in', '/etc/confluent/tls/ca/cacert.pem']
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).decode().replace('subject=', '')
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serial = subprocess.check_output(
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['openssl', 'x509', '-serial', '-noout', '-in', '/etc/confluent/tls/ca/cacert.pem']
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).decode().replace('serial=', '')
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with open('/etc/confluent/tls/ca-alt/serial', 'w') as srl:
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srl.write(serial)
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settings = {
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'dir': '/etc/confluent/tls/ca-alt',
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'certificate': '$dir/cacert.pem',
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'private_key': '$dir/private/cakey.pem',
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'countryName': 'optional',
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'stateOrProvinceName': 'optional',
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'organizationName': 'optional',
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}
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keyin = '/etc/confluent/tls/ca/private/cakey.pem'
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csrin = '/etc/confluent/tls/ca/ca.csr'
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shortname = 'r3u20'
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ipaddrs = list(certutil.get_ip_addresses())
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san = [] # 'IP:{0}'.format(x) for x in ipaddrs]
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# It is incorrect to put IP addresses as DNS type. However
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# there exists non-compliant clients that fail with them as IP
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# san.extend(['DNS:{0}'.format(x) for x in ipaddrs])
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dnsnames = set(ipaddrs)
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dnsnames.add(shortname)
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for currip in ipaddrs:
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dnsnames.add(socket.getnameinfo((currip, 0), 0)[0])
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for currname in dnsnames:
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san.append('DNS:{0}'.format(currname))
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if permitdomains[0] == '':
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permitdomains = []
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nameconstraints = ['permitted;DNS:{}'.format(x) for x in permitdomains]
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nameconstraints.extend(['permitted;{}'.format(x) for x in san])
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nameconstraints = ','.join(nameconstraints)
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if nameconstraints:
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nameconstraints = f'nameConstraints = critical,{nameconstraints}\n'
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certutil.mkdirp('/etc/confluent/tls/ca-alt/newcerts')
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with open('/etc/confluent/tls/ca-alt/index.txt', 'w') as idx:
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pass
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with open(sslcfg, 'r') as cfgin:
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with open(newcfg, 'w') as cfgfile:
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for line in cfgin.readlines():
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cfg = line.split('#')[0]
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if '=' in cfg:
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key, val = cfg.split('=', 1)
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for stg in settings:
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if certutil.substitute_cfg(stg, key, val, settings[stg], cfgfile, line):
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break
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else:
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cfgfile.write(line.strip() + '\n')
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continue
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cfgfile.write(line.strip() + '\n')
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cfgfile.write(f'\n[CACert]\nbasicConstraints = CA:true\n{nameconstraints}[ca_confluent]\n')
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subprocess.check_call(
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['openssl', 'ca', '-config', newcfg, '-batch', '-selfsign',
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'-extensions', 'CACert', '-extfile', newcfg,
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'-notext', '-startdate',
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'19700101010101Z', '-enddate', '21000101010101Z', '-keyfile',
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keyin, '-out', certout, '-in', csrin]
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)
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if __name__ == '__main__':
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create_alt_ca(sys.argv[1], sys.argv[2].split(','))
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