Check against the write encryption state, not the read state.

Change-Id: Ib3d8e02800e37bd089ef02c67a0b7e5dc009b1a5
Reviewed-on: https://boringssl-review.googlesource.com/8330
Reviewed-by: Nick Harper <nharper@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>

Decrypting is very easy to do in-place, but encrypting in-place is a hassle.
The rules actually were wrong due to record-splitting. The aliasing prefix and
the alignment prefix actually differ by 1. Take it out for now in preparation
for tightening the aliasing rules.

If we decide to do in-place encrypt later, probably it'd be more useful to
return header + in-place ciphertext + trailer. (That, in turn, needs a
scatter/gather thing on the AEAD thanks to TLS 1.3's padding and record type
construction.) We may also wish to rethink how record-splitting works here.

Change-Id: I0187d39c541e76ef933b7c2c193323164fd8a156
Reviewed-on: https://boringssl-review.googlesource.com/8230
Reviewed-by: Adam Langley <agl@google.com>

The business with ssl_record_prefix_len is rather a hassle. Instead, have
tls_open_record always decrypt in-place and give back a CBS to where the body
is.

This way the caller doesn't need to do an extra check all to avoid creating an
invalid pointer and underflow in subtraction.

Change-Id: I4e12b25a760870d8f8a503673ab00a2d774fc9ee
Reviewed-on: https://boringssl-review.googlesource.com/8173
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

Alert handling is more-or-less identical across all contexts. Push it down from
read_bytes into the low-level record functions. This also deduplicates the code
shared between TLS and DTLS.

Now the only type mismatch managed by read_bytes is if we get handshake data in
read_app_data.

Change-Id: Ia8331897b304566e66d901899cfbf31d2870194e
Reviewed-on: https://boringssl-review.googlesource.com/8124
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

This is getting a little repetitive.

Change-Id: Ib0fa8ab10149557c2d728b88648381b9368221d9
Reviewed-on: https://boringssl-review.googlesource.com/8126
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

In TLS 1.3, the actual record type is hidden within the encrypted data
and the record layer defaults to using a TLS 1.0 {3, 1} record version
for compatibility. Additionally the record layer no longer checks the
minor version of the record layer to maintain compatibility with the
TLS 1.3 spec.

Change-Id: If2c08e48baab170c1658e0715c33929d36c9be3a
Reviewed-on: https://boringssl-review.googlesource.com/8091
Reviewed-by: David Benjamin <davidben@google.com>

Both sides' signature and Finished checks still occur, but the results
are ignored. Also, all ciphers behave like the NULL cipher.
Conveniently, this isn't that much code since all ciphers and their size
computations funnel into SSL_AEAD_CTX.

This does carry some risk that we'll mess up this code. Up until now, we've
tried to avoid test-only changes to the SSL stack.

There is little risk that anyone will ship a BORINGSSL_UNSAFE_FUZZER_MODE build
for anything since it doesn't interop anyway. There is some risk that we'll end
up messing up the disableable checks. However, both skipped checks have
negative tests in runner (see tests that set InvalidSKXSignature and
BadFinished). For good measure, I've added a server variant of the existing
BadFinished test to this CL, although they hit the same code.

Change-Id: I37f6b4d62b43bc08fab7411965589b423d86f4b8
Reviewed-on: https://boringssl-review.googlesource.com/7287
Reviewed-by: Adam Langley <agl@google.com>

This removes the various non-PRF checks from SSL3_ENC_METHOD so that can
have a clearer purpose. It also makes TLS 1.0 through 1.2's
SSL3_ENC_METHOD tables identical and gives us an assert to ensure
nothing accesses the version bits before version negotiation.
Accordingly, ssl_needs_record_splitting was reordered slightly so we
don't rely on enc_method being initialized to TLS 1.2
pre-version-negotiation.

This leaves alert_value as the only part of SSL3_ENC_METHOD which may be
accessed before version negotiation.

Change-Id: If9e299e2ef5511b5fa442b2af654eed054c3e675
Reviewed-on: https://boringssl-review.googlesource.com/6842
Reviewed-by: Adam Langley <alangley@gmail.com>

Both are connection state rather than configuration state. Notably this
cuts down more of SSL_clear that can't just use ssl_free + ssl_new.

Change-Id: I3c05b3ae86d4db8bd75f1cd21656f57fc5b55ca9
Reviewed-on: https://boringssl-review.googlesource.com/6835
Reviewed-by: Adam Langley <alangley@gmail.com>

Move the actual SSL_AEAD_CTX swap into the record layer. Also revise the
intermediate state we store between setup_key_block and
change_cipher_state. With SSL_AEAD_CTX_new abstracted out, keeping the
EVP_AEAD around doesn't make much sense. Just store enough to partition
the key block.

Change-Id: I773fb46a2cb78fa570f00c0a89339c15bbb1d719
Reviewed-on: https://boringssl-review.googlesource.com/6832
Reviewed-by: Adam Langley <alangley@gmail.com>

Change-Id: I045a4d3e304872b8c97231dcde5bca7753a878fb
Reviewed-on: https://boringssl-review.googlesource.com/6831
Reviewed-by: Adam Langley <alangley@gmail.com>

It is redundant given the other state in the connection.

Change-Id: I5dc71627132659ab4316a5ea360c9ca480fb7c6c
Reviewed-on: https://boringssl-review.googlesource.com/6646
Reviewed-by: Adam Langley <agl@google.com>

This dates to SSLeay 0.8.0 (or earlier). The use counter sees virtually
no hits.

Change-Id: Iff4c8899d5cb0ba4afca113c66d15f1d980ffe41
Reviewed-on: https://boringssl-review.googlesource.com/6558
Reviewed-by: Adam Langley <agl@google.com>

These are theh two remaining quirks (SSL_OP_LEGACY_SERVER_CONNECT
aside). Add counters so we can determine whether there are still clients
that trip up these cases.

Change-Id: I7e92f42f3830c1df675445ec15a852e5659eb499
Reviewed-on: https://boringssl-review.googlesource.com/6290
Reviewed-by: Adam Langley <alangley@gmail.com>

The difference of two pointers is signed, even though it's always
non-negative here, so MSVC is complaining about signedness mismatch.

Change-Id: I5a042d06ed348540706b93310af3f60f3ab5f303
Reviewed-on: https://boringssl-review.googlesource.com/5766
Reviewed-by: Adam Langley <agl@google.com>

The old empty record logic discarded the records at a very low-level.
Let the error bubble up to ssl3_read_bytes so the type mismatch logic
may kick in before the empty record is skipped.

Add tests for when the record in question is application data, before
before the handshake and post ChangeCipherSpec.

BUG=521840

Change-Id: I47dff389cda65d6672b9be39d7d89490331063fa
Reviewed-on: https://boringssl-review.googlesource.com/5754
Reviewed-by: Adam Langley <agl@google.com>

This begins decoupling the transport from the SSL state machine. The buffering
logic is hidden behind an opaque API. Fields like ssl->packet and
ssl->packet_length are gone.

ssl3_get_record and dtls1_get_record now call low-level tls_open_record and
dtls_open_record functions that unpack a single record independent of who owns
the buffer. Both may be called in-place. This removes ssl->rstate which was
redundant with the buffer length.

Future work will push the buffer up the stack until it is above the handshake.
Then we can expose SSL_open and SSL_seal APIs which act like *_open_record but
return a slightly larger enum due to other events being possible. Likewise the
handshake state machine will be detached from its buffer. The existing
SSL_read, SSL_write, etc., APIs will be implemented on top of SSL_open, etc.,
combined with ssl_read_buffer_* and ssl_write_buffer_*. (Which is why
ssl_read_buffer_extend still tries to abstract between TLS's and DTLS's fairly
different needs.)

The new buffering logic does not support read-ahead (removed previously) since
it lacks a memmove on ssl_read_buffer_discard for TLS, but this could be added
if desired. The old buffering logic wasn't quite right anyway; it tried to
avoid the memmove in some cases and could get stuck too far into the buffer and
not accept records. (The only time the memmove is optional is in DTLS or if
enough of the record header is available to know that the entire next record
would fit in the buffer.)

The new logic also now actually decrypts the ciphertext in-place again, rather
than almost in-place when there's an explicit nonce/IV. (That accidentally
switched in https://boringssl-review.googlesource.com/#/c/4792/; see
3d59e04bce96474099ba76786a2337e99ae14505.)

BUG=468889

Change-Id: I403c1626253c46897f47c7ae93aeab1064b767b2
Reviewed-on: https://boringssl-review.googlesource.com/5715
Reviewed-by: Adam Langley <agl@google.com>