URL: https://github.com/freeipa/freeipa/pull/396 Author: stlaz Title: #396: Explicitly remove support of SSLv2 Action: opened
PR body: """ It was possible to set tls_version_min/max to 'ssl2', even though newer versions of NSS will fail to set this as a valid TLS version. This patch explicitly checks for deprecated TLS versions prior to creating a TLS connection. https://fedorahosted.org/freeipa/ticket/6607 """ To pull the PR as Git branch: git remote add ghfreeipa https://github.com/freeipa/freeipa git fetch ghfreeipa pull/396/head:pr396 git checkout pr396
From 4980a7bc7270cba3207daa4a5ce18029bec0a5bb Mon Sep 17 00:00:00 2001 From: Stanislav Laznicka <slazn...@redhat.com> Date: Fri, 13 Jan 2017 12:31:29 +0100 Subject: [PATCH] Explicitly remove support of SSLv2 It was possible to set tls_version_min/max to 'ssl2', even though newer versions of NSS will fail to set this as a valid TLS version. This patch explicitly checks for deprecated TLS versions prior to creating a TLS connection. https://fedorahosted.org/freeipa/ticket/6607 --- ipapython/nsslib.py | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 51 insertions(+), 2 deletions(-) diff --git a/ipapython/nsslib.py b/ipapython/nsslib.py index 08d05fc..7019867 100644 --- a/ipapython/nsslib.py +++ b/ipapython/nsslib.py @@ -23,6 +23,7 @@ import getpass import socket from ipapython.ipa_log_manager import root_logger +from ipalib.errors import InvocationError from nss.error import NSPRError import nss.io as io @@ -129,6 +130,52 @@ def client_auth_data_callback(ca_names, chosen_nickname, password, certdb): socket.AF_UNSPEC: io.PR_AF_UNSPEC } + +def get_proper_tls_version_span(tls_version_min, tls_version_max): + tls_versions = [ + "ssl2", + "ssl3", + "tls1.0", + "tls1.1", + "tls1.2" + ] + # every tls version from `tls_versions` prior to min_allowed_idx + # is deprecated in IPA + min_allowed_idx = tls_versions.index("ssl3") + + try: + min_version_idx = tls_versions.index(tls_version_min) + except ValueError: + raise InvocationError("API tls_version_min ('{val}') is not a known " + "TLS version.".format(val=tls_version_min)) + + try: + max_version_idx = tls_versions.index(tls_version_max) + except ValueError: + raise InvocationError("API tls_version_max ('{val}') is not a known " + "TLS version.".format(val=tls_version_max)) + + if min_version_idx > max_version_idx: + raise InvocationError("API tls_version_min is higher than " + "tls_version_max.") + + if min_version_idx < min_allowed_idx: + min_version_idx = min_allowed_idx + root_logger.warning("API tls_version_min set too low ('{old}')," + "using '{new}' instead" + .format(old=tls_version_min, + new=tls_versions[min_version_idx])) + + if max_version_idx < min_allowed_idx: + max_version_idx = min_version_idx + root_logger.warning("API tls_version_max set too low ('{old}')," + "using '{new}' instead" + .format(old=tls_version_max, + new=tls_versions[max_version_idx])) + + return tls_versions[min_version_idx:max_version_idx+1] + + class NSSAddressFamilyFallback(object): def __init__(self, family): self.sock_family = family @@ -217,8 +264,10 @@ def __init__(self, host, port=None, strict=None, ssl.set_domestic_policy() nss.set_password_callback(self.password_callback) - self.tls_version_min = str(tls_version_min) - self.tls_version_max = str(tls_version_max) + tls_versions = get_proper_tls_version_span( + tls_version_min, tls_version_max) + self.tls_version_min = tls_versions[0] + self.tls_version_max = tls_versions[-1] def _create_socket(self): ssl_enable_renegotiation = getattr(
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