Hi Raymond, On Tue, 3 Sept 2024 at 08:59, Raymond Mao <raymond....@linaro.org> wrote: > > Hi Simon, > > On Sat, 17 Aug 2024 at 11:58, Simon Glass <s...@chromium.org> wrote: >> >> Hi Raymond, >> >> On Fri, 16 Aug 2024 at 15:44, Raymond Mao <raymond....@linaro.org> wrote: >> > >> > 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_X509` is for replacing original X509, PKCS7, MSCode, ASN1, >> > and Pubkey parser with MbedTLS. >> > `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% >> > >> > Please see the latest output from buildman for size-growth on QEMU arm64, >> > Sandbox and Nanopi A64. [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. >> >> I wonder if we could leave out the SHA stuff? The algorithms are >> stable and this would seem to avoid much of the size growth, and all >> the pain of trying to integrate another yet another hashing layer (we >> already have normal, progressive and h/w acceleration, plus >> UCLASS_HASH which h/w acceleration should use but that migration never >> happened). I struggle to see any benefit in replacing U-Boot's very >> solid hashing infra with something else, particularly as this series >> adds yet another. Better to invest the time to refactor it. I asked >> about this before and was told that it would happen 'later'. Let's >> just not change it at all, then it is more likely someone will sort it >> out. >> > Unfortunately, MbedTLS depends on its own digest layer. Unless we patch > MbedTLS > to allow an external digest library from U-Boot ...
Yes that sounds best. It looks like only a few call sites, so it should be a matter of leaving out the MbedTLS code and adding some static inlines. > >> >> Also, if MbedTLS is wanting to be a general library for TLS (I assume >> transport-local security, not thread-local storage) perhaps it might >> consider changing to non-Windows newlines, or perhaps even kernel code >> style? >> > We can feedback this to the MbedTLS project when the first series are > accepted. OK. Regards, Simon
