[PATCH v5 00/27] Integrate MbedTLS v3.6 LTS with U-Boot

Tom Rini trini at konsulko.com
Thu Aug 1 22:46:06 CEST 2024


On Wed, Jul 31, 2024 at 10:25:10AM -0700, Raymond Mao 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.
> 
> Target(QEMU arm64) size-growth when enabling MbedTLS:
> v1: 6.03%
> v2: 4.66%
> From v3: 4.55%
> 
> Please see the latest output from buildman for size-growth on QEMU arm64,
> Sandbox and Nanopi A64. [1]

Let us inline the growth on qemu_arm64 for a moment:
   aarch64: (for 1/1 boards) all +6916.0 bss -32.0 data -64.0 rodata +200.0 text +6812.0
            qemu_arm64     : all +6916 bss -32 data -64 rodata +200 text +6812
               u-boot: add: 28/-17, grow: 12/-16 bytes: 15492/-8304 (7188)
                 function                                   old     new   delta
                 mbedtls_internal_sha1_process                -    4540   +4540
                 mbedtls_internal_md5_process                 -    2928   +2928
                 mbedtls_internal_sha256_process              -    2052   +2052
                 mbedtls_internal_sha512_process              -    1056   +1056
                 K                                            -     896    +896
                 mbedtls_sha512_finish                        -     556    +556
                 mbedtls_sha256_finish                        -     484    +484
                 mbedtls_sha1_finish                          -     420    +420
                 mbedtls_sha512_starts                        -     340    +340
                 mbedtls_md5_finish                           -     336    +336
                 mbedtls_sha512_update                        -     264    +264
                 mbedtls_sha256_update                        -     252    +252
                 mbedtls_sha1_update                          -     236    +236
                 mbedtls_md5_update                           -     236    +236
                 mbedtls_sha512                               -     148    +148
                 mbedtls_sha256_starts                        -     124    +124
                 hash_init_sha512                            52     128     +76
                 hash_init_sha256                            52     128     +76
                 mbedtls_sha1_starts                          -      72     +72
                 mbedtls_md5_starts                           -      60     +60
                 hash_init_sha1                              52     112     +60
                 mbedtls_platform_zeroize                     -      56     +56
                 mbedtls_sha512_free                          -      16     +16
                 mbedtls_sha256_free                          -      16     +16
                 mbedtls_sha1_free                            -      16     +16
                 mbedtls_md5_free                             -      16     +16
                 hash_finish_sha512                          72      88     +16
                 hash_finish_sha256                          72      88     +16
                 hash_finish_sha1                            72      88     +16
                 sha512_csum_wd                              68      80     +12
                 sha256_csum_wd                              68      80     +12
                 sha1_csum_wd                                68      80     +12
                 md5_wd                                      68      80     +12
                 mbedtls_sha512_init                          -      12     +12
                 mbedtls_sha256_init                          -      12     +12
                 mbedtls_sha1_init                            -      12     +12
                 mbedtls_md5_init                             -      12     +12
                 memset_func                                  -       8      +8
                 sha512_update                                4       8      +4
                 sha384_update                                4       8      +4
                 sha256_update                               12       8      -4
                 sha1_update                                 12       8      -4
                 sha256_process                              16       -     -16
                 sha1_process                                16       -     -16
                 hash_update_sha512                          36      16     -20
                 hash_update_sha256                          36      16     -20
                 hash_update_sha1                            36      16     -20
                 MD5Init                                     56      36     -20
                 sha1_starts                                 60      36     -24
                 hash_update_sha384                          36       -     -36
                 hash_init_sha384                            52       -     -52
                 sha384_csum_wd                              68      12     -56
                 sha256_starts                              104      40     -64
                 sha256_padding                              64       -     -64
                 sha1_padding                                64       -     -64
                 hash_finish_sha384                          72       -     -72
                 sha512_finish                              152      36    -116
                 sha512_starts                              168      40    -128
                 sha384_starts                              168      40    -128
                 sha384_finish                              152       4    -148
                 MD5Final                                   196      44    -152
                 sha512_base_do_finalize                    160       -    -160
                 static.sha256_update                       228       -    -228
                 static.sha1_update                         240       -    -240
                 sha512_base_do_update                      244       -    -244
                 MD5Update                                  260       -    -260
                 sha1_finish                                300      36    -264
                 sha256_finish                              404      36    -368
                 sha256_armv8_ce_process                    428       -    -428
                 sha1_armv8_ce_process                      484       -    -484
                 sha512_K                                   640       -    -640
                 sha512_block_fn                           1212       -   -1212
                 MD5Transform                              2552       -   -2552

And to start with, that's not bad. In fact, tossing LTO in before mbedTLS only changes
the top-line a little:
   aarch64: (for 1/1 boards) all +5120.0 bss -16.0 data -64.0 rodata +200.0 text +5000.0
            qemu_arm64     : all +5120 bss -16 data -64 rodata +200 text +5000
               u-boot: add: 19/-18, grow: 11/-7 bytes: 14696/-7884 (6812)

But, is there something we can do still? mbedTLS is a more robust
solution and I'm accepting there will be growth. But still the
process/start/finish is much larger. Is there something configurable
there?

-- 
Tom
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