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Code Issues Releases Wiki Activity

idna domains in certificate subject alternative names were not handled correctly after switching to cryptography package

This commit is contained in:
Joshua Tauberer 2015-06-30 12:53:56 +00:00
parent aa33428311
commit e3252f53da
1 changed files with 13 additions and 3 deletions
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16
management/status_checks.py
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@ -612,6 +612,7 @@ def check_certificate(domain, ssl_certificate, ssl_private_key, warn_if_expiring
from cryptography.hazmat.primitives.asymmetric.rsa import RSAPrivateKey
from cryptography.x509 import Certificate, DNSName, ExtensionNotFound, OID_COMMON_NAME, OID_SUBJECT_ALTERNATIVE_NAME
import idna
# The ssl_certificate file may contain a chain of certificates. We'll
# need to split that up before we can pass anything to openssl or
@ -626,7 +627,8 @@ def check_certificate(domain, ssl_certificate, ssl_private_key, warn_if_expiring
# First check that the domain name is one of the names allowed by
# the certificate.
if domain is not None:
# The domain must be found in the Subject Common Name (CN)...
# The domain may be found in the Subject Common Name (CN). This comes back as an IDNA (ASCII)
# string, which is the format we store domains in - so good.
certificate_names = set()
try:
certificate_names.add(
@ -637,11 +639,19 @@ def check_certificate(domain, ssl_certificate, ssl_private_key, warn_if_expiring
# But we'll let it error-out when it doesn't find the domain.
pass
# ... or be one of the Subject Alternative Names.
# ... or be one of the Subject Alternative Names. The cryptography library handily IDNA-decodes
# the names for us. We must encode back to ASCII, but wildcard certificates can't pass through
# IDNA encoding/decoding so we must special-case. See https://github.com/pyca/cryptography/pull/2071.
def idna_decode_dns_name(dns_name):
if dns_name.startswith("*."):
return "*." + idna.encode(dns_name[2:]).decode('ascii')
else:
return idna.encode(dns_name).decode('ascii')
try:
sans = cert.extensions.get_extension_for_oid(OID_SUBJECT_ALTERNATIVE_NAME).value.get_values_for_type(DNSName)
for san in sans:
certificate_names.add(san)
certificate_names.add(idna_decode_dns_name(san))
except ExtensionNotFound:
pass