The previous code writes the content (the EC curve list) of the extension
before writing the extension length field at the beginning, which is common
in the library in places where we don't know the length upfront. Here,
however, we do traverse the EC curve list upfront to infer its length
and do the bounds check, so we can reorder the code to write the extension
linearly and hence improve readability.
This commit introduces the option MBEDTLS_SSL_CONF_SINGLE_EC
which can be used to register a single supported elliptic curve
at compile time. It replaces the runtime configuration API
mbedtls_ssl_conf_curves() which allows to register a _list_
of supported elliptic curves.
In contrast to other options used to hardcode configuration options,
MBEDTLS_SSL_CONF_SINGLE_EC isn't a numeric option, but instead it's
only relevant if it's defined or not. To actually set the single
elliptic curve that should be supported, numeric options
MBEDTLS_SSL_CONF_SINGLE_EC_TLS_ID
MBEDTLS_SSL_CONF_SINGLE_EC_GRP_ID
must both be defined and provide the TLS ID and the Mbed TLS internal
ID and the chosen curve, respectively.
For both client/server the EC curve list is assumed not to be NULL:
- On the client-side, it's assumed when writing the
supported elliptic curve extension:
c54ee936d7/library/ssl_cli.c (L316)
- On the server, it is assumed when searching for a
suitable curve for the ECDHE exchange:
c54ee936d7/library/ssl_srv.c (L3200)
It is therefore not necessary to check this in mbedtls_ssl_check_curve().
ssl_write_supported_elliptic_curves_ext() is guarded by
```
#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
```
each of which implies (by check_config.h) that MBEDTLS_ECP_C
is enabled.
The fields
- mbedtls_ssl_handshake_params::max_major_ver,
- mbedtls_ssl_handshake_params::max_minor_ver
are used only for server-side RSA-based key exchanges
can be removed otherwise.
Reasons:
- If the transport type is fixed at compile-time,
mbedtls_ssl_read_version() and mbedtls_ssl_write_version()
are called with a compile-time determined `transport`
parameter, so the transport-type branch in their body
can be eliminated at compile-time.
- mbedtls_ssl_read_version() is called with addresses of
local variables, which so far need to be put on the stack
to be addressable. Inlining the call allows to read directly
into the registers holding these local variables.
This saves 60 bytes w.r.t. the measurement performed by
> ./scripts/baremetal.sh --rom --gcc
If the minor/major version is enforced at compile-time, the `major_ver`
and `minor_ver` fields in `mbedtls_ssl_context` are redundant and can
be removed.
This commit introduces the numeric compile-time constants
- MBEDTLS_SSL_CONF_MIN_MINOR_VER
- MBEDTLS_SSL_CONF_MAX_MINOR_VER
- MBEDTLS_SSL_CONF_MIN_MAJOR_VER
- MBEDTLS_SSL_CONF_MAX_MAJOR_VER
which, when defined, overwrite the runtime configurable fields
mbedtls_ssl_config::min_major_ver etc. in the SSL configuration.
As for the preceding case of the ExtendedMasterSecret configuration,
it also introduces and puts to use getter functions for these variables
which evaluate to either a field access or the macro value, maintaining
readability of the code.
The runtime configuration API mbedtls_ssl_conf_{min|max}_version()
is kept for now but has no effect if MBEDTLS_SSL_CONF_XXX are set.
This is likely to be changed in a later commit but deliberately omitted
for now, in order to be able to study code-size benefits earlier in the
process.
* origin/mbedtls-2.16:
Fix parsing issue when int parameter is in base 16
Refactor receive_uint32()
Refactor get_byte function
Make the script portable to both pythons
Update the test encoding to support python3
update the test script
tests: Limit each log to 10 GiB
* origin/pr/2744:
Fix parsing issue when int parameter is in base 16
Refactor receive_uint32()
Refactor get_byte function
Make the script portable to both pythons
Update the test encoding to support python3
update the test script
Fix error `ValueError: invalid literal for int() with base 10:` that
is caused when a parameter is given in base 16. Use relevant base
when calling `int()` function.
Call `greentea_getc()` 8 times, and then `unhexify` once, instead of
calling `receive_byte()`, which inside calls `greentea_getc()` twice,
for every hex digit.
Since Python3 handles encoding differently than Python2,
a change in the way the data is encoded and sent to the target is needed.
1. Change the test data to be sent as hex string
2. Convert the characters to binary bytes.
This is done because the mbed tools translate the encoding differently
(mbed-greentea, and mbed-htrunner)
Limit log output in compat.sh and ssl-opt.sh, in case of failures with
these scripts where they may output seemingly unlimited length error
logs.
Note that ulimit -f uses units of 512 bytes, so we use 10 * 1024 * 1024
* 2 to get 10 GiB.
* origin/mbedtls-2.16:
Split _abi_compliance_command into smaller functions
Record the commits that were compared
Document how to build the typical argument for -s
Allow running /somewhere/else/path/to/abi_check.py
Allow TODO in code
Use the docstring in the command line help
* origin/pr/2739:
Split _abi_compliance_command into smaller functions
Record the commits that were compared
Document how to build the typical argument for -s
Allow running /somewhere/else/path/to/abi_check.py
* origin/mbedtls-2.16:
Changelog entry for HAVEGE fix
Prevent building the HAVEGE module on platforms where it doesn't work
Fix misuse of signed ints in the HAVEGE module
The failure of mbedtls_md was not checked in one place. This could have led
to an incorrect computation if a hardware accelerator failed. In most cases
this would have led to the key exchange failing, so the impact would have been
a hard-to-diagnose error reported in the wrong place. If the two sides of the
key exchange failed in the same way with an output from mbedtls_md that was
independent of the input, this could have led to an apparently successful key
exchange with a predictable key, thus a glitching md accelerator could have
caused a security vulnerability.
