This way, it's not required that the label is null-terminated. This
allows us to avoid an allocation in
mbedtls_ssl_tls12_export_keying_material().
Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
Previously, if MBEDTLS_SSL_CONTEXT_SERIALIZATION is not defined,
randbytes are not stored after the handshake is done, but they are
needed for TLS-Exporter in TLS 1.2.
This commit also saves randbytes if MBEDTLS_SSL_PROTO_TLS1_2 is defined.
Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
The length of the generated key must fit into a uint16_t, so it must not
be larger than 0xffff.
Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
RFC 8446 made it look like we can't use Derive-Secret for the second
step, but actually, Transcript-Hash and Hash are the same thing, so we
can.
Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
The TLS-Exporter is a function to derive shared symmetric keys for the
server and client from the secrets generated during the handshake.
It is defined in RFC 8446, Section 7.5 for TLS 1.3 and in RFC 5705 for
TLS 1.2.
Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
This should avoid running into a bug with printf format specifiers one
windows.
It's also a logical move for actual tests: I used the highest debug
level for discovery, but we don't need that all the time.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
A handshake record may contain multiple handshake messages, or multiple
fragments (there can be the final fragment of a pending message, then zero
or more whole messages, and an initial fragment of an incomplete message).
This was previously untested, but supported, so don't break it.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Reassemble handshake fragments incrementally instead of all at the end. That
is, every time we receive a non-initial handshake fragment, append it to the
initial fragment. Since we only have to deal with at most two handshake
fragments at the same time, this simplifies the code (no re-parsing of a
record) and is a little more memory-efficient (no need to store one record
header per record).
This commit also fixes a bug. The previous code did not calculate offsets
correctly when records use an explicit IV, which is the case in TLS 1.2 with
CBC (encrypt-then-MAC or not), GCM and CCM encryption (i.e. all but null and
ChachaPoly). This led to the wrong data when an encrypted handshake message
was fragmented (Finished or renegotiation). The new code handles this
correctly.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Minor refactoring of the initial checks and preparation when receiving the
first fragment. Use `ssl->in_hsfraglen` to determine whether there is a
pending handshake fragment, for consistency, and possibly for more
robustness in case handshake fragments are mixed with non-handshake
records (although this is not currently supported anyway).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In preparation for reworking mbedtls_ssl_prepare_handshake_record(),
tweak the "handshake fragment:" log message.
This changes what information is displayed when a record contains data
beyond the expected end of the handshake message. This case is currently
untested and its handling will change in a subsequent commit.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
