Add OP_NO_TLSv1_3

[tiran]

BPO	29136
Nosy	@larryhastings, @tiran, @benjaminp, @ned-deily, @alex, @Lukasa
PRs	bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 #1363 [3.6] bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 (GH-1363) #3444 [2.7] bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 (GH-1363) #3446 bpo-29136: Fix versionchange for TLS 1.3 changes #3483 [2.7] bpo-29136: Fix from test_ssl test_default_ecdh_curve #11877

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/tiran'
closed_at = <Date 2017-09-10.19:15:14.587>
created_at = <Date 2017-01-02.21:07:24.729>
labels = ['expert-SSL', 'type-feature', '3.7']
title = 'Add OP_NO_TLSv1_3'
updated_at = <Date 2019-02-15.15:31:23.753>
user = 'https://github.com/tiran'

bugs.python.org fields:

activity = <Date 2019-02-15.15:31:23.753>
actor = 'cstratak'
assignee = 'christian.heimes'
closed = True
closed_date = <Date 2017-09-10.19:15:14.587>
closer = 'christian.heimes'
components = ['SSL']
creation = <Date 2017-01-02.21:07:24.729>
creator = 'christian.heimes'
dependencies = []
files = []
hgrepos = []
issue_num = 29136
keywords = ['patch']
message_count = 14.0
messages = ['284504', '284509', '286032', '286094', '286096', '286239', '301654', '301662', '301674', '301678', '301803', '301820', '301828', '301829']
nosy_count = 7.0
nosy_names = ['larry', 'christian.heimes', 'benjamin.peterson', 'ned.deily', 'Arfrever', 'alex', 'Lukasa']
pr_nums = ['1363', '3444', '3446', '3483', '11877']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue29136'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7']

[tiran]

OpenSSL 1.1.1 is going to provide TLS 1.3. The preferred protocols PROTOCOL_TLS (old name PROTOCOL_SSLv23), PROTOCOL_TLS_CLIENT and PROTOCOL_TLS_SERVER are going to have TLS 1.3 enabled by default. In order to disable TLS 1.3, let's add OP_NO_TLSv1_3 to _ssl.c and guard it with #ifdef SSL_OP_NO_TLSv1_3

https://github.com/openssl/openssl/blob/d2e491f225d465b11f18a466bf399d4a899cb50e/include/openssl/ssl.h#L346

Benjamin, Larry, Ned, are you ok with a new flag? OpenSSL 1.1.1 won't be available any time soon. I like to add the flag *after* the upcoming round of releases.

[benjaminp]

I think that's fine for 2.7.

On Mon, Jan 2, 2017, at 13:07, Christian Heimes wrote:

New submission from Christian Heimes:

OpenSSL 1.1.1 is going to provide TLS 1.3. The preferred protocols
PROTOCOL_TLS (old name PROTOCOL_SSLv23), PROTOCOL_TLS_CLIENT and
PROTOCOL_TLS_SERVER are going to have TLS 1.3 enabled by default. In
order to disable TLS 1.3, let's add OP_NO_TLSv1_3 to _ssl.c and guard it
with #ifdef SSL_OP_NO_TLSv1_3

https://github.com/openssl/openssl/blob/d2e491f225d465b11f18a466bf399d4a899cb50e/include/openssl/ssl.h#L346

Benjamin, Larry, Ned, are you ok with a new flag? OpenSSL 1.1.1 won't be
available any time soon. I like to add the flag *after* the upcoming
round of releases.

----------
assignee: christian.heimes
components: SSL
messages: 284504
nosy: benjamin.peterson, christian.heimes, larry, ned.deily
priority: normal
severity: normal
stage: needs patch
status: open
title: Add OP_NO_TLSv1_3
type: enhancement
versions: Python 2.7, Python 3.5, Python 3.6, Python 3.7

---

Python tracker <report@bugs.python.org>
<http://bugs.python.org/issue29136\>

---

[tiran]

memo to me: Update the TLS cipher list to include TLS 1.3 ciphers. TLS 1.3 uses a disjunct set of cipher suites. No member of the current cipher suite set is compatible with TLS 1.3. Handshake with TLS 1.3 enabled servers is going to fail.

As of today OpenSSL 1.1.1-dev provides one of five TLS 1.3 ciphers: TLS13-AES-128-GCM-SHA256. TLS13-AES-256-GCM-SHA384 and TLS13-CHACHA20-POLY1305 are not yet implemented as are CCM block mode.

[alex]

We can easily just add TLS13:... at the from of our ciphersuite list and it'll be ok though right? (Note to self, do the same in urllib3, twisted, requests, god only knows what else)

[tiran]

No, of course it does not work (yet):

$ LD_LIBRARY_PATH=. apps/openssl ciphers TLS13
Error in cipher list
140546693477888:error:1410D0B9:SSL routines:SSL_CTX_set_cipher_list:no cipher match:ssl/ssl_lib.c:2100:

[Lukasa]

For those who want to keep track, the relevant OpenSSL ticket for configuring TLSv1.3 cipher suites is openssl/openssl#2276.

[tiran]

PR 1363 also introduced ssl.HAS_TLSv1_3 flag for unit tests. The flag is required because OpenSSL 1.1.1-dev can be compiled without TLS 1.3 support. The development version always defines OP_NO_TLSv1_3 to a non-zero value. Further more the PR adds a test for TLS 1.3.

[tiran]

New changeset cb5b68a by Christian Heimes in branch 'master':
bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 (bpo-1363)
cb5b68a

[tiran]

New changeset 9f2b3d4 by Christian Heimes in branch '3.6':
[3.6] bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 (GH-1363) (bpo-3444)
9f2b3d4

[tiran]

New changeset b9a860f by Christian Heimes in branch '2.7':
[2.7] bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3 (GH-1363) (bpo-3446)
b9a860f

[Arfrever]

In backport to 2.7 branch, ".. versionadded:: 2.7.15" and ".. versionchanged:: 2.7.15" were used.

However, in backport to 3.6 branch, ".. versionadded:: 3.7" and ".. versionchanged:: 3.7" were used, instead of expected ".. versionadded:: 3.6.3" and ".. versionchanged:: 3.6.3".

[tiran]

Good catch, thanks! I'll update the documentation.

[tiran]

New changeset 2858031 by Christian Heimes in branch '3.6':
bpo-29136: Fix versionchange for TLS 1.3 changes (bpo-3483)
2858031

[tiran]

Thanks, I fixed versionchanged.