Raymond Mao <raymond.mao@linaro.org> says:
Integrate MbedTLS v3.6 LTS (currently v3.6.0) with U-Boot.
Motivations:
------------
1. MbedTLS is well maintained with LTS versions.
2. LWIP is integrated with MbedTLS and easily to enable HTTPS.
3. MbedTLS recently switched license back to GPLv2.
Prerequisite:
-------------
This patch series requires mbedtls git repo to be added as a
subtree to the main U-Boot repo via:
$ git subtree add --prefix lib/mbedtls/external/mbedtls \
https://github.com/Mbed-TLS/mbedtls.git \
v3.6.0 --squash
Moreover, due to the Windows-style files from mbedtls git repo,
we need to convert the CRLF endings to LF and do a commit manually:
$ git add --renormalize .
$ git commit
New Kconfig options:
--------------------
`MBEDTLS_LIB` is for MbedTLS general switch.
`MBEDTLS_LIB_CRYPTO` is for replacing original digest and crypto libs with
MbedTLS.
`MBEDTLS_LIB_CRYPTO_ALT` is for using original U-Boot crypto libs as
MbedTLS crypto alternatives.
`MBEDTLS_LIB_X509` is for replacing original X509, PKCS7, MSCode, ASN1,
and Pubkey parser with MbedTLS.
By default `MBEDTLS_LIB_CRYPTO_ALT` and `MBEDTLS_LIB_X509` are selected
when `MBEDTLS_LIB` is enabled.
`LEGACY_CRYPTO` is introduced as a main switch for legacy crypto library.
`LEGACY_CRYPTO_BASIC` is for the basic crypto functionalities and
`LEGACY_CRYPTO_CERT` is for the certificate related functionalities.
For each of the algorithm, a pair of `<alg>_LEGACY` and `<alg>_MBEDTLS`
Kconfig options are introduced. Meanwhile, `SPL_` Kconfig options are
introduced.
In this patch set, MBEDTLS_LIB, MBEDTLS_LIB_CRYPTO and MBEDTLS_LIB_X509
are by default enabled in qemu_arm64_defconfig and sandbox_defconfig
for testing purpose.
Patches for external MbedTLS project:
-------------------------------------
Since U-Boot uses Microsoft Authentication Code to verify PE/COFFs
executables which is not supported by MbedTLS at the moment,
addtional patches for MbedTLS are created to adapt with the EFI loader:
1. Decoding of Microsoft Authentication Code.
2. Decoding of PKCS#9 Authenticate Attributes.
3. Extending MbedTLS PKCS#7 lib to support multiple signer's certificates.
4. MbedTLS native test suites for PKCS#7 signer's info.
All above 4 patches (tagged with `mbedtls/external`) are submitted to
MbedTLS project and being reviewed, eventually they should be part of
MbedTLS LTS release.
But before that, please merge them into U-Boot, otherwise the building
will be broken when MBEDTLS_LIB_X509 is enabled.
See below PR link for the reference:
https://github.com/Mbed-TLS/mbedtls/pull/9001
Miscellaneous:
--------------
Optimized MbedTLS library size by tailoring the config file
and disabling all unnecessary features for EFI loader.
From v2, original libs (rsa, asn1_decoder, rsa_helper, md5, sha1, sha256,
sha512) are completely replaced when MbedTLS is enabled.
From v3, the size-growth is slightly reduced by refactoring Hash functions.
From v6, smaller implementations for SHA256 and SHA512 are enabled and
target size reduce significantly.
Target(QEMU arm64) size-growth when enabling MbedTLS:
v1: 6.03%
v2: 4.66%
v3 - v5: 4.55%
v6: 2.90%
Tests done:
-----------
EFI Secure Boot test (EFI variables loading and verifying, EFI signed image
verifying and booting) via U-Boot console.
EFI Secure Boot and Capsule sandbox test passed.
Known issues:
-------------
None.
Link: https://lore.kernel.org/u-boot/20241003215112.3103601-1-raymond.mao@linaro.org/