The Zephyr configuration was enabling the memory buffer allocator (but
not using it) without defining enough other features to allow it to
compile (undefined reference to `exit()`).
Disable the memory buffer allocator when just using the ASN.1 library,
and conditionalize the heap itself to avoid using the RAM for that.
Signed-off-by: David Brown <david.brown@linaro.org>
When building with ECDSA P-256 as the signature algorithm, we are still
bringing in SHA256 and some ASN.1 code from mbed TLS. Fix part of this
by wrapping the hash functions with general routines (inline functions)
allowing to select between mbed TLS and Tinycrypt for the
implementation.
Update the Zephyr config files so that the Tinycrypt version is used
when building the ECDSA P-256 signing variant.
There are some problems with how mbed TLS is configured in Zephyr.
First, include the makefile stub in the Makefile that uses these
defines. This makes sure the right definitions get made so that our
custom config gets used for all compiled files, rather than a mixed set.
Also, fix up the wrappers on the custom configs so that each is
different, making it easier to detect if multiple configs are being
included.
Lastly, only include the right header in the image validation. The mbed
TLS includes don't seem to want to allow both RSA and ECDSA to be used
(due to the key size), and including the wrong header results in a
compilation error.
Make it clear in the top-level Makefile how to configure mcuboot for
Zephyr for a particular signing algorithm. Currently supported, are the
RSA signatures, and ECDSA with the P-256 curve. These configuration
lines will select the code built in the bootloader, as well as which
public key gets included with the image.
This also adds a demo public key for the P-256 signatures.
David Brown