[Kimchi-devel] [PATCH] Prevent Kimchi against TLS Logjam attacks
Aline Manera
alinefm at linux.vnet.ibm.com
Thu Jun 18 18:33:54 UTC 2015
On 18/06/2015 15:26, Rodrigo Trujillo wrote:
> There are several weaknesses in how Diffie-Hellman key exchange has been
> deployed, allowing a man-in-the-middle attack named Logjam, more details
> here: https://weakdh.org.
> This patch improves the security in Nginx server, generating 2048bit
> DH-Parameters or longer when using 2048bit RSA keys.
>
> Some parameters before patch:
> echo | openssl s_client -connect localhost:8001 -cipher "DH"
> Cipher : DHE-RSA-AES256-GCM-SHA384
> New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-GCM-SHA384
> Server public key is 2048 bit
> Server Temp Key: DH, 1024 bits
>
> Some parameters after patch:
> echo | openssl s_client -connect localhost:8001 -cipher "DH"
> Cipher : DHE-RSA-AES256-GCM-SHA384
> New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-GCM-SHA384
> Server public key is 2048 bit
> Server Temp Key: DH, 2048 bits (*)
>
> This patch also changes the Ciphers allowed by Nginx, change build
> scripts and the RPM spec file to deliver new file: dhparams.pem.
>
> Signed-off-by: Rodrigo Trujillo <rodrigo.trujillo at linux.vnet.ibm.com>
> ---
> Makefile.am | 1 +
> contrib/kimchi.spec.fedora.in | 3 ++-
> src/Makefile.am | 8 +++++++-
> src/kimchi/proxy.py | 6 +++++-
> src/nginx/Makefile.am | 2 ++
> src/nginx/kimchi.conf.in | 4 +++-
> 6 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/Makefile.am b/Makefile.am
> index 46b0b5b..5f2b401 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -133,6 +133,7 @@ install-data-local:
> touch $(DESTDIR)/var/log/kimchi/kimchi-access.log
> touch $(DESTDIR)/var/log/kimchi/kimchi-error.log
> mkdir -p $(DESTDIR)/etc/kimchi/
> + $(INSTALL_DATA) src/nginx/dhparams.pem $(DESTDIR)/etc/kimchi/dhparams.pem
> touch $(DESTDIR)/etc/nginx/conf.d/kimchi.conf
>
> uninstall-local:
> diff --git a/contrib/kimchi.spec.fedora.in b/contrib/kimchi.spec.fedora.in
> index dc5533a..de40fd1 100644
> --- a/contrib/kimchi.spec.fedora.in
> +++ b/contrib/kimchi.spec.fedora.in
> @@ -34,6 +34,7 @@ Requires: python-ldap
> Requires: python-libguestfs
> Requires: libguestfs-tools
> BuildRequires: libxslt
> +BuildRequires: openssl
> BuildRequires: python-lxml
>
> %if 0%{?rhel} >= 6 || 0%{?fedora} >= 19
> @@ -153,7 +154,7 @@ rm -rf $RPM_BUILD_ROOT
> %{_sysconfdir}/kimchi/distros.d/opensuse.json
> %{_sysconfdir}/kimchi/distros.d/ubuntu.json
> %{_sysconfdir}/kimchi/distros.d/gentoo.json
> -%{_sysconfdir}/kimchi/
> +%{_sysconfdir}/kimchi/*
Isn't this change needed to kimchi.spec.suse.in too?
> %{_sharedstatedir}/kimchi/debugreports/
> %{_sharedstatedir}/kimchi/screenshots/
> %{_sharedstatedir}/kimchi/vnc-tokens/
> diff --git a/src/Makefile.am b/src/Makefile.am
> index 38d231c..e0e0821 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -45,4 +45,10 @@ kimchid: kimchid.in Makefile
> kimchi.conf: kimchi.conf.in Makefile
> $(do_substitution) < kimchi.conf.in > kimchi.conf
>
> -CLEANFILES = $(bin_SCRIPTS) $(BUILT_SOURCES)
> +# Generate unique Diffie-Hellman group with 2048-bit
> +all-local: dhparams.pem
> +
> +dhparams.pem:
> + openssl dhparam -out dhparams.pem 2048
> +
> +CLEANFILES = $(bin_SCRIPTS) $(BUILT_SOURCES) dhparams.pem
> diff --git a/src/kimchi/proxy.py b/src/kimchi/proxy.py
> index e3e35b4..5dcca65 100644
> --- a/src/kimchi/proxy.py
> +++ b/src/kimchi/proxy.py
> @@ -68,6 +68,9 @@ def _create_proxy_config(options):
> with open(key, "w") as f:
> f.write(ssl_gen.key_pem())
>
> + # Setting up Diffie-Hellman group with 2048-bit file
> + dhparams_pem = os.path.join(config_dir, "dhparams.pem")
> +
> # Read template file and create a new config file
> # with the specified parameters.
> with open(os.path.join(nginx_config_dir, "kimchi.conf.in")) as template:
> @@ -78,7 +81,8 @@ def _create_proxy_config(options):
> kimchid_port=options.cherrypy_port,
> proxy_ssl_port=options.ssl_port,
> cert_pem=cert, cert_key=key,
> - max_body_size=eval(options.max_body_size))
> + max_body_size=eval(options.max_body_size),
> + dhparams_pem=dhparams_pem)
>
> # Write file to be used for nginx.
> config_file = open(os.path.join(nginx_config_dir, "kimchi.conf"), "w")
> diff --git a/src/nginx/Makefile.am b/src/nginx/Makefile.am
> index 0241b37..c754947 100644
> --- a/src/nginx/Makefile.am
> +++ b/src/nginx/Makefile.am
> @@ -21,3 +21,5 @@ EXTRA_DIST = kimchi.conf.in
>
> confdir = $(sysconfdir)/nginx/conf.d
> dist_conf_DATA = kimchi.conf.in
> +
> +CLEANFILES = kimchi.conf
> diff --git a/src/nginx/kimchi.conf.in b/src/nginx/kimchi.conf.in
> index 3ecbde4..b0faea3 100644
> --- a/src/nginx/kimchi.conf.in
> +++ b/src/nginx/kimchi.conf.in
> @@ -53,7 +53,9 @@ http {
> ssl_certificate ${cert_pem};
> ssl_certificate_key ${cert_key};
> ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
> - ssl_ciphers ECDH at STRENGTH:DH at STRENGTH:HIGH:!RC4:!MD5:!DES:!aNULL:!eNULL;
> + ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA:@STRENGTH';
> + ssl_prefer_server_ciphers on;
> + ssl_dhparam ${dhparams_pem};
>
> add_header Strict-Transport-Security "max-age=31536000; includeSubdomains;";
> add_header X-Frame-Options DENY;
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