[PATCH v4 00/29] Integrate MbedTLS v3.6 LTS with U-Boot

[Simon Glass]

Hi Raymond,

On Wed, 24 Jul 2024 at 08:35, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Hi Tom,
>
> On Tue, 2 Jul 2024 at 21:26, Tom Rini <trini at konsulko.com> wrote:
>>
>> On Tue, Jul 02, 2024 at 11:22:36AM -0700, Raymond Mao wrote:
>>
>> > Integrate MbedTLS v3.6 LTS (currently v3.6.0-RC1) 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_X509` is for replacing original X509, PKCS7, MSCode, ASN1,
>> > and Pubkey parser with MbedTLS.
>> > `MBEDTLS_LIB_TLS` is for SSL/TLS (Disabled until LWIP port for MbedTLS is
>> > ready).
>> > `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 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.
>> >
>> > Target(QEMU arm64) size-growth when enabling MbedTLS:
>> > v1: 6.03%
>> > v2: 4.66%
>> > v3 & v4: 4.55%
>> >
>> > Please see the latest output of bloat-o-meter for the reference of the
>> > size-growth on QEMU arm64 target [1].
>> >
>> > 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.
>> >
>> > [1]: bloat-o-meter output between disabling/enabling MbedTLS (QEMU arm64)
>> > ```
>> > add/remove: 206/81 grow/shrink: 19/17 up/down: 55548/-17495 (38053)
>>
>> bloat-o-meter is a bit off then, since buildman shows:
>> u-boot: add: 243/-17, grow: 18/-17 bytes: 65723/-8480 (57243)
>>
>> (Please use buildman for the size comparisons in the future).
>>
> The reason that buildman is showing more growth is because I enable
> "CONFIG_EFI_SECURE_BOOT=y" in my patch, which is off by default
> for qemu_arm64.
> Since the buildman is always comparing one local branch with the
> 'upstream' (I didn't find a way to let it compare two local branches or maybe
> I am wrong), I guess I have to first merge one commit with just enabling
> CONFIG_EFI_SECURE_BOOT to solve this. But I get this makes less
> value...

Yes, that's one way to do it. It cannot compare two branches. It only
compares one commit with the next.

>
> I think it is better to use sandbox for comparison from v5,
> and I will add one more platform (e.g. imx8mp) for reference.

Regards,
Simon