[PATCH v8 03/27] lib: Adapt digest header files to MbedTLS

[Ilias Apalodimas]

On Wed, 9 Oct 2024 at 18:32, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Hi Tom,
>
> On Wed, 9 Oct 2024 at 10:38, Tom Rini <trini at konsulko.com> wrote:
>>
>> On Thu, Oct 03, 2024 at 02:50:16PM -0700, Raymond Mao wrote:
>>
>> > Adapt digest header files to support both original libs and MbedTLS
>> > by switching on/off MBEDTLS_LIB_CRYPTO.
>> > Introduce <alg>_LEGACY kconfig for legacy hash implementations.
>> > sha256.o should depend on SHA256 kconfig only but not SUPPORT_EMMC_RPMB,
>> > SHA256 should be selected when SUPPORT_EMMC_RPMB is enabled instead.
>> >
>> > `IS_ENABLED` or `CONFIG_IS_ENABLED` is not applicable here, since
>> > including <linux/kconfig.h> causes undefined reference on schedule()
>> > with sandbox build, as <linux/kconfig.h> includes <generated/autoconf.h>
>> > which enables `CONFIG_HW_WATCHDOG` and `CONFIG_WATCHDOG` but no schedule()
>> > are defined in sandbox build,
>> > Thus we use `#if defined(CONFIG_MBEDTLS_LIB_CRYPTO)` instead.
>> >
>> > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
>> > Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>>
>> There's three platforms where we see something like:
>>        arm: (for 1/1 boards) all +5651.0 data +112.0 rodata +139.0 text +5400.0
>>             o4-imx6ull-nano: all +5651 data +112 rodata +139 text +5400
>>                u-boot: add: 23/0, grow: 1/0 bytes: 1172/0 (1172)
>>                  function                                   old     new   delta
>>                  hash_command                               108     296    +188
>>                  sha1_finish                                  -     156    +156
>>                  static.sha1_update                           -     114    +114
>>                  hash_algo                                    -     112    +112
>>                  sha1_padding                                 -      64     +64
>>                  hash_lookup_algo                             -      60     +60
>>                  sha1_starts                                  -      52     +52
>>                  crc16_ccitt_wd_buf                           -      36     +36
>>                  sha256_csum_wd                               -      34     +34
>>                  sha1_csum_wd                                 -      34     +34
>>                  hash_finish_sha256                           -      34     +34
>>                  hash_finish_sha1                             -      34     +34
>>                  crc32_wd_buf                                 -      34     +34
>>                  hash_finish_crc32                            -      28     +28
>>                  hash_finish_crc16_ccitt                      -      28     +28
>>                  hash_init_sha256                             -      22     +22
>>                  hash_init_sha1                               -      22     +22
>>                  hash_update_crc32                            -      20     +20
>>                  hash_update_crc16_ccitt                      -      20     +20
>>                  hash_init_crc32                              -      20     +20
>>                  hash_init_crc16_ccitt                        -      20     +20
>>                  hash_update_sha256                           -      16     +16
>>                  hash_update_sha1                             -      16     +16
>>                  sha1_update                                  -       8      +8
>>
>> This is because:
>> > diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
>> > index 982e84dc3bc..5d7fd904950 100644
>> > --- a/drivers/mmc/Kconfig
>> > +++ b/drivers/mmc/Kconfig
>> > @@ -119,6 +119,7 @@ config MMC_HW_PARTITIONING
>> >  config SUPPORT_EMMC_RPMB
>> >       bool "Support eMMC replay protected memory block (RPMB)"
>> >       imply CMD_MMC_RPMB
>> > +     select SHA256
>> >       help
>> >         Enable support for reading, writing and programming the
>> >         key for the Replay Protection Memory Block partition in eMMC.
>>
>> Wasn't true / required before now, no hashing algorithms were enabled.
>> This was fine because:
>> [snip]
>> > diff --git a/lib/Makefile b/lib/Makefile
>> > index c4950b78a29..33755778283 100644
>> > --- a/lib/Makefile
>> > +++ b/lib/Makefile
>> > @@ -50,7 +50,6 @@ obj-$(CONFIG_XXHASH) += xxhash.o
>> >  obj-y += net_utils.o
>> >  obj-$(CONFIG_PHYSMEM) += physmem.o
>> >  obj-y += rc4.o
>> > -obj-$(CONFIG_SUPPORT_EMMC_RPMB) += sha256.o
>> >  obj-$(CONFIG_RBTREE) += rbtree.o
>> >  obj-$(CONFIG_BITREVERSE) += bitrev.o
>> >  obj-y += list_sort.o
>>
>> Got us the library access without bringing in everything else. And since
>> two of the platforms that are hitting this now are "nano" this is an
>> important thing to figure out how to continue to support. If there's
>> just no way around it, we can likely live with the size increase, but
>> I'd like to see this looked in to specifically first, thanks!
>>
> To address this, I think there are two options.
> 1. Introduce SUPPORT_EMMC_RPMB into the MbedTLS sub makefile.
> 2. Make MBEDTLS_LIB_CRYPTO depends on !SUPPORT_EMMC_RPMB.
> 1) looks to be ugly, I prefer 2) if you agree.

2 is not a good idea either. We can't just drop RPMB support when
mbedTLS is enabled

Thanks
/Ilias
>
> Regards,
> Raymond