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

[Raymond Mao]

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...

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,
Raymond