** Description changed:
+ [Impact]
+
+ Applications using GnuTLS OpenSSL compat layer [1] are be unable to use
+ modern TLS versions (1.1 and 1.2) when relying on the
+ SSLv23_{client,server}_method functions.
+
+ There is an industry-wide push to use modern TLS versions, see [2] and
+ [3] for example.
+
+ The proposed fix changes the compat layer to use GnuTLS' "NORMAL"
+ priority [4] instead of hard-coding which protocol versions and ciphers
+ to enable.
+
+ [Test Case]
+
+ 1) Setup a mail submission server that uses StartTLS
+ 2) Setup sSMTP (uses GnuTLS OpenSSL compat layer) to relay
+ through the mail relay using StartTLS
+ 3) Send an email while capturing with tcpdump/tshark
+ 4) Inspect the submission connection (TCP/587) and look for the protocol
+ version negotiated by the client.
+
+ Without the fix, you should see TLSv1.0. With the fix, it should be
+ TLSv1.2.
+
+ Please see the original issue description for more details.
+
+ [Regression Potential]
+
+ Regression risk should be low since it's a backport of a simple fix that
+ landed in Debian in April 2017.
+
+ [References]
+
+ 1: $ apt-cache rdepends libgnutls-openssl27
+ libgnutls-openssl27
+ Reverse Depends:
+ libgnutls-dev
+ libgnutls-dev
+ zoneminder
+ yaskkserv
+ tf5
+ ssmtp
+ snowdrop
+ sngrep
+ slrnpull
+ slrn
+ sipsak
+ macopix-gtk2
+ gnss-sdr
+ gkrellm
+ freewheeling
+ boinctui
+ iputils-ping
+
+ 2: https://lists.debian.org/debian-devel-announce/2017/08/msg00004.html
+ 3: https://blog.pcisecuritystandards.org/migrating-from-ssl-and-early-tls
+ 4: https://gnutls.org/manual/html_node/Priority-Strings.html
+
+
+ [Original issue description]
+
sSMTP is limited to using TLSv1.0 and the "old" ciphers that come with
it. Here's a packet capture when ssmtp connects to smtp.sdeziel.info:587
that offers TLSv1.0 and higher:
$ tshark -ta -Vr submission.pcap | sed -n '/^Frame 14:/,/^Frame 15:/ p' |
grep -E '^[[:space:]]+(Version|Cipher|Handshake Protocol)'
- Version: TLS 1.0 (0x0301)
- Handshake Protocol: Client Hello
- Version: TLS 1.0 (0x0301)
- Cipher Suites Length: 30
- Cipher Suites (15 suites)
- Cipher Suite: TLS_RSA_WITH_AES_128_CBC_SHA (0x002f)
- Cipher Suite: TLS_RSA_WITH_AES_256_CBC_SHA (0x0035)
- Cipher Suite: TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (0x0041)
- Cipher Suite: TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (0x0084)
- Cipher Suite: TLS_RSA_WITH_3DES_EDE_CBC_SHA (0x000a)
- Cipher Suite: TLS_DHE_RSA_WITH_AES_128_CBC_SHA (0x0033)
- Cipher Suite: TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x0039)
- Cipher Suite: TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (0x0045)
- Cipher Suite: TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (0x0088)
- Cipher Suite: TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (0x0016)
- Cipher Suite: TLS_DHE_DSS_WITH_AES_128_CBC_SHA (0x0032)
- Cipher Suite: TLS_DHE_DSS_WITH_AES_256_CBC_SHA (0x0038)
- Cipher Suite: TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA (0x0044)
- Cipher Suite: TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA (0x0087)
- Cipher Suite: TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA (0x0013)
+ Version: TLS 1.0 (0x0301)
+ Handshake Protocol: Client Hello
+ Version: TLS 1.0 (0x0301)
+ Cipher Suites Length: 30
+ Cipher Suites (15 suites)
+ Cipher Suite: TLS_RSA_WITH_AES_128_CBC_SHA (0x002f)
+ Cipher Suite: TLS_RSA_WITH_AES_256_CBC_SHA (0x0035)
+ Cipher Suite: TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (0x0041)
+ Cipher Suite: TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (0x0084)
+ Cipher Suite: TLS_RSA_WITH_3DES_EDE_CBC_SHA (0x000a)
+ Cipher Suite: TLS_DHE_RSA_WITH_AES_128_CBC_SHA (0x0033)
+ Cipher Suite: TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x0039)
+ Cipher Suite: TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (0x0045)
+ Cipher Suite: TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (0x0088)
+ Cipher Suite: TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (0x0016)
+ Cipher Suite: TLS_DHE_DSS_WITH_AES_128_CBC_SHA (0x0032)
+ Cipher Suite: TLS_DHE_DSS_WITH_AES_256_CBC_SHA (0x0038)
+ Cipher Suite: TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA (0x0044)
+ Cipher Suite: TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA (0x0087)
+ Cipher Suite: TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA (0x0013)
I would expect ssmtp to use TLSv1.2 and a recent cipher like the openssl
s_client is able to do:
$ echo | openssl s_client -connect smtp.sdeziel.info:587 -starttls smtp
2>/dev/null | grep -E '^[[:space:]]+(Protocol|Cipher)'
- Protocol : TLSv1.2
- Cipher : ECDHE-RSA-AES128-GCM-SHA256
-
+ Protocol : TLSv1.2
+ Cipher : ECDHE-RSA-AES128-GCM-SHA256
Additional information:
$ lsb_release -rd
Description: Ubuntu 16.04.3 LTS
Release: 16.04
$ apt-cache policy ssmtp libgnutls-openssl27
ssmtp:
- Installed: 2.64-8ubuntu1
- Candidate: 2.64-8ubuntu1
- Version table:
- *** 2.64-8ubuntu1 500
- 500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
- 100 /var/lib/dpkg/status
+ Installed: 2.64-8ubuntu1
+ Candidate: 2.64-8ubuntu1
+ Version table:
+ *** 2.64-8ubuntu1 500
+ 500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
+ 100 /var/lib/dpkg/status
libgnutls-openssl27:
- Installed: 3.4.10-4ubuntu1.3
- Candidate: 3.4.10-4ubuntu1.3
- Version table:
- *** 3.4.10-4ubuntu1.3 500
- 500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64
Packages
- 500 http://security.ubuntu.com/ubuntu xenial-security/main amd64
Packages
- 100 /var/lib/dpkg/status
- 3.4.10-4ubuntu1 500
- 500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
+ Installed: 3.4.10-4ubuntu1.3
+ Candidate: 3.4.10-4ubuntu1.3
+ Version table:
+ *** 3.4.10-4ubuntu1.3 500
+ 500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64
Packages
+ 500 http://security.ubuntu.com/ubuntu xenial-security/main amd64
Packages
+ 100 /var/lib/dpkg/status
+ 3.4.10-4ubuntu1 500
+ 500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ssmtp 2.64-8ubuntu1 [modified: etc/ssmtp/revaliases]
ProcVersionSignature: Ubuntu 4.4.0-89.112-generic 4.4.76
Uname: Linux 4.4.0-89-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
Date: Mon Aug 7 18:13:33 2017
ProcEnviron:
- TERM=xterm
- PATH=(custom, no user)
- LANG=en_US.UTF-8
- SHELL=/bin/bash
+ TERM=xterm
+ PATH=(custom, no user)
+ LANG=en_US.UTF-8
+ SHELL=/bin/bash
SourcePackage: ssmtp
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.ssmtp.revaliases: [modified]
mtime.conffile..etc.ssmtp.revaliases: 2017-08-05T13:44:06.274302
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https://bugs.launchpad.net/bugs/1709193
Title:
Unable to use TLSv1.1 or 1.2 with OpenSSL compat layer
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