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

Thu Jul 25 15:36:28 CEST 2024

Hi Tom,

On Wed, 24 Jul 2024 at 18:42, Tom Rini <trini at konsulko.com> wrote:

> On Wed, Jul 24, 2024 at 10:34:50AM -0400, Raymond Mao 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...
> >
> > I think it is better to use sandbox for comparison from v5,
> > and I will add one more platform (e.g. imx8mp) for reference.
>
> Please note that I check the world before/after, not just single
> platforms, for size growth. I'll note some examples of issues when I
> find them, typically. And with the wrapper I posted, sometimes I will
> "--all" a platform to see which commit increases things.
>
> For your reference, below size-growth is for v5 (qemu_arm64, nanopi_a64,
sandbox):

aarch64: (for 2/2 boards) all +582.0 bss +40.0 data -64.0 rodata +206.0
text +400.0
  qemu_arm64     : all +7040 bss +80 data -64 rodata +212 text +6812
    u-boot: add: 28/-17, grow: 12/-16 bytes: 15492/-8304 (7188)
  nanopi_a64     : all -5876 data -64 rodata +200 text -6012
    u-boot: add: 21/-8, grow: 4/-8 bytes: 12312/-4364 (7948)
sandbox: (for 1/1 boards) all +22416.0 data +1440.0 rodata -4160.0 text
+25136.0
  sandbox        : all +22416 data +1440 rodata -4160 text +25136
    u-boot: add: 253/-203, grow: 115/-61 bytes: 93168/-76647 (16521)

I think the size-growth should be reasonable.
I will attach the details in v5 cover-letter.

Regards,
Raymond