Later CLs will clean up the ClientHello construction a bit (draft-12
avoids computing ClientHelloOuter twice). I suspect the transcript
handling on the client can also be simpler, but I'll see what's
convenient after I've changed how ClientHelloOuter is constructed.
Changes of note between draft-10 and draft-13:
- There is now an ECH confirmation signal in both HRR and SH. We don't
actually make much use of this in our client right now, but it
resolves a bunch of weird issues around HRR, including edge cases if
HRR applies to one ClientHello but not the other.
- The confirmation signal no longer depends on key_share and PSK, so we
don't have to work around a weird ordering issue.
- ech_is_inner is now folded into the main encrypted_client_hello code
point. This works better with some stuff around HRR.
- Padding is moved from the padding extension, computed with
ClientHelloInner, to something we fill in afterwards. This makes it
easier to pad up the whole thing to a multiple of 32. I've accordingly
updated to the latest recommended padding construction, and updated
the GREASE logic to match.
- ech_outer_extensions is much easier to process because the order is
required to be consistent. We were doing that anyway, and now a simple
linear scan works.
- ClientHelloOuterAAD now uses an all zero placeholder payload of the
same length. This lets us simplify the server code, but, for now, I've
kept the client code the same. I'll follow this up with a CL to avoid
computing ClientHelloOuter twice.
- ClientHelloOuterAAD is allowed to contain a placeholder PSK. I haven't
filled that in and will do it in a follow-up CL.
Bug: 275
Change-Id: I7464345125c53968b2fe692f9268e392120fc2eb
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48912
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
If a client offers ECH, but the server rejects it, the client completes
the handshake with ClientHelloOuter in order to authenticate retry keys.
Implement this flow. This is largely allowing the existing handshake to
proceed, but with some changes:
- Certificate verification uses the other name. This CL routes this up to
the built-in verifier and adds SSL_get0_ech_name_override for the
callback.
- We need to disable False Start to pick up server Finished in TLS 1.2.
- Client certificates, notably in TLS 1.3 where they're encrypted,
should only be revealed to the true server. Fortunately, not sending
client certs is always an option, so do that.
Channel ID has a similar issue. I've just omitted the extension in
ClientHelloOuter because it's deprecated and is unlikely to be used
with ECH at this point. ALPS may be worth some pondering but, the way
it's currently used, is not sensitive.
(Possibly we should change the draft to terminate the handshake before
even sending that flight...)
- The session is never offered in ClientHelloOuter, but our internal
book-keeping doesn't quite notice.
I had to replace ech_accept with a tri-state ech_status to correctly
handle an edge case in SSL_get0_ech_name_override: when ECH + 0-RTT +
reverify_on_resume are all enabled, the first certificate verification
is for the 0-RTT session and should be against the true name, yet we
have selected_ech_config && !ech_accept. A tri-state tracks when ECH is
actually rejected. I've maintained this on the server as well, though
the server never actually cares.
Bug: 275
Change-Id: Ie55966ca3dc4ffcc8c381479f0fe9bcacd34d0f8
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48135
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Based on an initial implementation by Dan McArdle at
https://boringssl-review.googlesource.com/c/boringssl/+/46784
This CL contains most of a client implementation for
draft-ietf-tls-esni-10. The pieces missing so far, which will be done in
follow-up CLs are:
1. While the ClientHelloInner is padded, the server Certificate message
is not. I'll add that once we resolve the spec discussions on how to
do that. (We were originally going to use TLS record-level padding,
but that doesn't work well with QUIC.)
2. The client should check the public name is a valid DNS name before
copying it into ClientHelloOuter.server_name.
3. The ClientHelloOuter handshake flow is not yet implemented. This CL
can detect when the server selects ClientHelloOuter, but for now the
handshake immediately fails. A follow-up CL will remove that logic
and instead add the APIs and extra checks needed.
Otherwise, this should be complete, including padding and compression.
The main interesting point design-wise is that we run through
ClientHello construction multiple times. We need to construct
ClientHelloInner and ClientHelloOuter. Then each of those has slight
variants: EncodedClientHelloInner is the compressed form, and
ClientHelloOuterAAD just has the ECH extension erased to avoid a
circular dependency.
I've computed ClientHelloInner and EncodedClientHelloInner concurrently
because the compression scheme requires shifting the extensions around
to be contiguous. However, I've computed ClientHelloOuterAAD and
ClientHelloOuter by running through the logic twice. This probably can
be done better, but the next draft revises the construction anyway, so
I'm thinking I'll rework it then. (In the next draft, we use a
placeholder payload of the same length, so we can construct the
ClientHello once and fill in the payload.)
Additionally, now that we have a client available in ssl_test, this adds
a threading test to confirm that SSL_CTX_set1_ech_keys is properly
synchronized. (Confirmed that, if I drop the lock in
SSL_CTX_set1_ech_keys, TSan notices.)
Change-Id: Icaff68b595035bdcc73c468ff638e67c84239ef4
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48004
Reviewed-by: Adam Langley <agl@google.com>
We'll probably need to make this more complex later, but this should be
a start. I had hoped this would also simplify tests, MakeECHConfig() was
still needed to generate weird inputs for tests. I've instead tidied
that up a bit with a params structure. Now the only hard-coded ECHConfig
in tests is to check the output of the new API.
Bug: 275
Change-Id: I640a224fb4b7a7d20e8a2cd7a1e75d1e3fe69936
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48003
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
The first thing any deployment will want to monitor is whether ECH was
actually used. Also it's useful if the command-line tool can output
this. (The alert is how the client signals it discarded the connection
due to ECH reject.)
This also disables ECH with the handoff mechanism for now. (The
immediate cause being that ech_accept isn't serialized.) We'll probably
need to make some decisions around the ordering here, since ECH affects
where the true ClientHello is available.
Bug: 275
Change-Id: Ie4559733290e653a514fcd94431090bf86bc3172
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47911
Reviewed-by: Adam Langley <agl@google.com>
See go/handshake-hints (internal).
CL originally by Bin Wu <wub@google.com>. I just reworked the tests and
tidied it up a bit. This is the start of a replacement for the split
handshakes API. For now, only TLS 1.3 is supported. It starts with an
initial set of hints, but we can add more later. (In particular, we
should probably apply the remote handshaker's extension order to avoid
needing to capability protect such changes.)
Change-Id: I7b6a6dfaa84c6c6e3436d2a4026c3652b8a79f0f
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/46535
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
See also 86a90dc749af91f8a7b8da6628c9ffca2bae3009 from upstream. This
differs from upstream's which treats {NULL, 2} as a valid way to spell
the empty list. (I think this is a mistake and have asked them about
it.)
Upstream's CL also, for them, newly makes the empty list disable ALPN,
when previously they'd disable it but misread it as a malloc failure.
For us, we'd already fixed the misreading due to our switch to
bssl::Array and bssl::Span, but the documentation was odd. This CL
preserves that behavior, but updates the documentation and writes a
test.
Update-Note: SSL_CTX_set_alpn_protos and SSL_set_alpn_protos will now
reject invalud inputs. Previously, they would accept them, but silently
send an invalid ALPN extension which the server would almost certainly
error on.
Change-Id: Id5830b2d8c3a5cee4712878fe92ee350c4914367
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/46804
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
This CL adds an initial implementation of the ECH server, with pieces of
the client in BoGo as necessary for testing. In particular, the server
supports ClientHelloInner compression with ech_outer_extensions. When
ECH decryption fails, it can send retry_configs back to the client.
This server passes the "ech-accept" and "ech-reject" test cases in
tls-interop-runner[0] when tested against both the cloudflare-go and nss
clients. For reproducibility, I started with the main branch at commit
707604c262d8bcf3e944ed1d5a675077304732ce and updated the endpoint's
script to pass the server's ECHConfig and private key to the boringssl
tool.
Follow-up CLs will update HPKE to the latest draft and catch us up to
draft-10.
[0]: https://github.com/xvzcf/tls-interop-runner
Bug: 275
Change-Id: I49be35af46d1fd5dd9c62252f07d0bae179381ab
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45285
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
This aligns with OpenSSL's behavior. RFC7301 says servers should return
no_application_protocol if the client supported ALPN but no common
protocol was found. We currently interpret all values as
SSL_TLSEXT_ERR_NOACK. Instead, implement both modes and give guidance on
whne to use each. (NOACK is still useful because the callback may be
shared across multiple configurations, some of which don't support ALPN
at all. Those would want to return NOACK to ignore the list.)
To match upstream, I've also switched SSL_R_MISSING_ALPN, added for
QUIC, to SSL_R_NO_APPLICATION_PROTOCOL.
Update-Note: Callers that return SSL_TLSEXT_ERR_ALERT_FATAL from the
ALPN callback will change behavior. The old behavior may be restored by
returning SSL_TLSEXT_ERR_NOACK, though see the documentation for new
recommendations on return values.
Change-Id: Ib7917b5f8a098571bed764c79aa7a4ce0f728297
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45504
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
(Original CL by svaldez, reworked by davidben.)
Change-Id: I8570808fa5e96a1c9e6e03c4877039a22e73254f
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42404
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Update-Note: If an SSL_QUIC_METHOD is set, connections will now fail if
ALPN is not negotiated. This new behavior can be detected by checking
if the value of BORINGSSL_API_VERSION is greater than 10.
Bug: 294
Change-Id: I42fb80aa09268e77cec4a51e49cdad79bd72fa58
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42304
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Reason codes 1000+N correspond to receiving an alert N from the peer,
rather than observing the corresponding error condition locally. This
has generally been a source of confusion for folks.
They were originally named like SSL_R_TLSV1_ALERT_DECRYPTION_FAILED, but
OpenSSL introduced a few without the "ALERT" token in
739a543ea863682f157e9aa0ee382367eb3d187c.
We then inadvertently carried the mistake over in
SSL_R_TLSV1_UNKNOWN_PSK_IDENTITY and SSL_R_TLSV1_CERTIFICATE_REQUIRED.
Fix all these to include the "ALERT" for consistency and make it
slightly less confusing. (Although perhaps it should have been
RECEIVED_ALERT or so.) Add compatibility #defines for the original
OpenSSL ones and SSL_R_TLSV1_CERTIFICATE_REQUIRED. The latter can be
removed when downstream code is fixed. The OpenSSL ones we'll probably
just leave around.
Update-Note: The renamed alerts will log slightly different strings, but
the constants used by external code are still there.
Bug: 366
Change-Id: I30c299c4ad4b2bed695bd71d0831fbe6755975a7
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42384
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
David Benjamin
Daniel McArdle
Steven Valdez
Nick Harper
Adam Langley