[U-Boot] [PATCH] verified-boot: Minimal support for booting U-Boot proper from SPL

Sumit Garg sumit.garg at nxp.com
Thu Jun 2 06:40:18 CEST 2016


> -----Original Message-----
> From: Teddy Reed [mailto:teddy.reed at gmail.com]
> Sent: Tuesday, May 31, 2016 2:23 AM
> To: Sumit Garg <sumit.garg at nxp.com>
> Cc: sjg at chromium.org; dannenberg at ti.com; u-boot at lists.denx.de; Ruchika
> Gupta <ruchika.gupta at nxp.com>; Aneesh Bansal <aneesh.bansal at nxp.com>
> Subject: Re: [PATCH] verified-boot: Minimal support for booting U-Boot proper
> from SPL
> 
> Hi Sumit!
> 
> On Sun, May 29, 2016 at 10:32 PM, Sumit Garg <sumit.garg at nxp.com> wrote:
> > Can you make this support more generic as you have used only
> CONFIG_SPL_FIT_SIGNATURE for SPL verified boot while our platforms doesn't
> use fit signature approach for verification?
> >
> 
> CONFIG_SPL_FIT_SIGNATURE only adds ./lib/rsa/rsa-{checksum,verify}.c
> 
> And the only related change is to mimic the existing CONFIG_FIT_SIGNATURE
> option.
> 
> This patch only allows an SPL to include the verified boot implementation from
> U-Boot proper. I would like to keep it as simple and concise as possible.
> 
> Generalizing the various verified/secure boot methods that exist within U-Boot
> would be a much larger effort. :)
> 
> > May be you can use CONFIG_SPL_VERIFIED_BOOT?
> >
> 
> In your previous proposed patch [1], I don't see anything modifying
> ./lib/rsa/rsa-{checksum,verify}.c. The patch does include the ./lib/rsa directory
> outside of the non-SPL build, but that is not enough to add the RSA verify and
> checksum implementationd. I believe your affected boards will still need
> CONFIG_FIT_SIGNATURE.
> 
> Are you suggesting we should rename CONFIG_FIT_SIGNATURE to
> CONFIG_SPL_VERIFIED_BOOT? :)
> 
> If that's the case, this patch is NOT the place to perform that refactor/rename.
> Since that will also need to update tooling, build configs, the existing U-Boot
> proper verified boot documentation, and several board configurations. It will
> also render quite a few guides/walkthroughs obsolete so broader
> communication may be needed.

Yeah you are correct this patch is not meant for refactoring. So rather I will define
only CONFIG_SPL_CRYPTO_SUPPORT, CONFIG_SPL_RSA & CONFIG_SPL_HASH_SUPPORT
for our platform and skip CONFIG_SPL_FIT_SIGNATURE.

> 
> [1] http://lists.denx.de/pipermail/u-boot/2016-May/256133.html
> 
> >> -----Original Message-----
> >> From: Teddy Reed [mailto:teddy.reed at gmail.com]
> >> Sent: Sunday, May 29, 2016 7:28 AM
> >> To: u-boot at lists.denx.de
> >> Cc: sjg at chromium.org; dannenberg at ti.com; Sumit Garg
> >> <sumit.garg at nxp.com>
> >> Subject: [PATCH] verified-boot: Minimal support for booting U-Boot
> >> proper from SPL
> >>
> >> This allows a board to configure verified boot within the SPL using a
> >> FIT or FIT with external data. It also allows the SPL to perform
> >> signature verification without needing relocation.
> >>
> >> The board configuration will need to add the following feature defines:
> >> CONFIG_SPL_CRYPTO_SUPPORT
> >> CONFIG_SPL_HASH_SUPPORT
> >> CONFIG_SPL_SHA256
> >>
> >> In this example, SHA256 is the only selected hashing algorithm.
> >>
> >> And the following booleans:
> >> CONFIG_SPL=y
> >> CONFIG_SPL_DM=y
> >> CONFIG_SPL_LOAD_FIT=y
> >> CONFIG_SPL_FIT=y
> >> CONFIG_SPL_OF_CONTROL=y
> >> CONFIG_SPL_OF_LIBFDT=y
> >> CONFIG_SPL_FIT_SIGNATURE=y
> >>
> >> Signed-off-by: Teddy Reed <teddy.reed at gmail.com>
> >> Cc: Simon Glass <sjg at chromium.org>
> >> Cc: Andreas Dannenberg <dannenberg at ti.com>
> >> ---
> >>  Kconfig                                 | 11 +++++++++++
> >>  common/Makefile                         |  1 +
> >>  drivers/Makefile                        |  1 +
> >>  drivers/crypto/rsa_mod_exp/mod_exp_sw.c |  1 +
> >>  lib/Makefile                            |  9 ++++-----
> >>  lib/rsa/Kconfig                         |  4 ++++
> >>  lib/rsa/Makefile                        |  2 +-
> >>  7 files changed, 23 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/Kconfig b/Kconfig
> >> index 4b46216..817f4f0 100644
> >> --- a/Kconfig
> >> +++ b/Kconfig
> >> @@ -183,6 +183,11 @@ config FIT
> >>         verified boot (secure boot using RSA). This option enables that
> >>         feature.
> >>
> >> +config SPL_FIT
> >> +     bool "Support Flattened Image Tree within SPL"
> >> +     depends on FIT
> >> +     depends on SPL
> >> +
> >>  config FIT_VERBOSE
> >>       bool "Display verbose messages on FIT boot"
> >>       depends on FIT
> >> @@ -205,6 +210,12 @@ config FIT_SIGNATURE
> >>         format support in this case, enable it using
> >>         CONFIG_IMAGE_FORMAT_LEGACY.
> >>
> >> +config SPL_FIT_SIGNATURE
> >> +     bool "Enable signature verification of FIT firmware within SPL"
> >> +     depends on SPL_FIT
> >> +     depends on SPL_DM
> >> +     select SPL_RSA
> >> +
> >>  config FIT_BEST_MATCH
> >>       bool "Select the best match for the kernel device tree"
> >>       depends on FIT
> >> diff --git a/common/Makefile b/common/Makefile index 0562d5c..e6b0c22
> >> 100644
> >> --- a/common/Makefile
> >> +++ b/common/Makefile
> >> @@ -93,6 +93,7 @@ obj-$(CONFIG_USB_KEYBOARD) += usb_kbd.o  endif #
> >> !CONFIG_SPL_BUILD
> >>
> >>  ifdef CONFIG_SPL_BUILD
> >> +obj-$(CONFIG_SPL_HASH_SUPPORT) += hash.o
> >>  obj-$(CONFIG_ENV_IS_IN_FLASH) += env_flash.o
> >>  obj-$(CONFIG_SPL_YMODEM_SUPPORT) += xyzModem.o
> >>  obj-$(CONFIG_SPL_NET_SUPPORT) += miiphyutil.o diff --git
> >> a/drivers/Makefile b/drivers/Makefile index 99dd07f..772d437 100644
> >> --- a/drivers/Makefile
> >> +++ b/drivers/Makefile
> >> @@ -10,6 +10,7 @@ obj-$(CONFIG_$(SPL_)RAM)    += ram/
> >>
> >>  ifdef CONFIG_SPL_BUILD
> >>
> >> +obj-$(CONFIG_SPL_CRYPTO_SUPPORT) += crypto/
> >>  obj-$(CONFIG_SPL_I2C_SUPPORT) += i2c/
> >>  obj-$(CONFIG_SPL_GPIO_SUPPORT) += gpio/
> >>  obj-$(CONFIG_SPL_MMC_SUPPORT) += mmc/ diff --git
> >> a/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> >> b/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> >> index dc6c064..3817fb3 100644
> >> --- a/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> >> +++ b/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> >> @@ -32,6 +32,7 @@ U_BOOT_DRIVER(mod_exp_sw) = {
> >>       .name   = "mod_exp_sw",
> >>       .id     = UCLASS_MOD_EXP,
> >>       .ops    = &mod_exp_ops_sw,
> >> +     .flags  = DM_FLAG_PRE_RELOC,
> >>  };
> >>
> >>  U_BOOT_DEVICE(mod_exp_sw) = {
> >> diff --git a/lib/Makefile b/lib/Makefile index 02dfa29..0df5395
> >> 100644
> >> --- a/lib/Makefile
> >> +++ b/lib/Makefile
> >> @@ -9,7 +9,6 @@ ifndef CONFIG_SPL_BUILD
> >>
> >>  obj-$(CONFIG_EFI) += efi/
> >>  obj-$(CONFIG_EFI_LOADER) += efi_loader/
> >> -obj-$(CONFIG_RSA) += rsa/
> >>  obj-$(CONFIG_LZMA) += lzma/
> >>  obj-$(CONFIG_LZO) += lzo/
> >>  obj-$(CONFIG_ZLIB) += zlib/
> >> @@ -25,8 +24,6 @@ obj-y += crc8.o
> >>  obj-y += crc16.o
> >>  obj-$(CONFIG_ERRNO_STR) += errno_str.o
> >>  obj-$(CONFIG_FIT) += fdtdec_common.o
> >> -obj-$(CONFIG_$(SPL_)OF_CONTROL) += fdtdec_common.o
> >> -obj-$(CONFIG_$(SPL_)OF_CONTROL) += fdtdec.o
> >>  obj-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o
> >>  obj-$(CONFIG_GZIP) += gunzip.o
> >>  obj-$(CONFIG_GZIP_COMPRESSED) += gzip.o @@ -39,9 +36,7 @@ obj-y +=
> >> net_utils.o
> >>  obj-$(CONFIG_PHYSMEM) += physmem.o
> >>  obj-y += qsort.o
> >>  obj-y += rc4.o
> >> -obj-$(CONFIG_SHA1) += sha1.o
> >>  obj-$(CONFIG_SUPPORT_EMMC_RPMB) += sha256.o
> >> -obj-$(CONFIG_SHA256) += sha256.o
> >>  obj-y        += strmhz.o
> >>  obj-$(CONFIG_TPM) += tpm.o
> >>  obj-$(CONFIG_RBTREE) += rbtree.o
> >> @@ -49,6 +44,10 @@ obj-$(CONFIG_BITREVERSE) += bitrev.o  obj-y +=
> >> list_sort.o  endif
> >>
> >> +obj-$(CONFIG_$(SPL_)RSA) += rsa/
> >> +obj-$(CONFIG_$(SPL_)SHA1) += sha1.o
> >> +obj-$(CONFIG_$(SPL_)SHA256) += sha256.o
> >> +
> >>  obj-$(CONFIG_$(SPL_)OF_LIBFDT) += libfdt/  ifdef
> >> CONFIG_SPL_OF_CONTROL
> >>  obj-$(CONFIG_OF_LIBFDT) += libfdt/
> >> diff --git a/lib/rsa/Kconfig b/lib/rsa/Kconfig index 86df0a0..09ec358
> >> 100644
> >> --- a/lib/rsa/Kconfig
> >> +++ b/lib/rsa/Kconfig
> >> @@ -13,6 +13,10 @@ config RSA
> >>         option. The software based modular exponentiation is built into
> >>         mkimage irrespective of this option.
> >>
> >> +config SPL_RSA
> >> +     bool "Use RSA Library within SPL"
> >> +     depends on RSA
> >> +
> >>  if RSA
> >>  config RSA_SOFTWARE_EXP
> >>       bool "Enable driver for RSA Modular Exponentiation in software"
> >> diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile index
> >> 6867e50..4b2c1ba 100644
> >> --- a/lib/rsa/Makefile
> >> +++ b/lib/rsa/Makefile
> >> @@ -7,5 +7,5 @@
> >>  # SPDX-License-Identifier:   GPL-2.0+
> >>  #
> >>
> >> -obj-$(CONFIG_FIT_SIGNATURE) += rsa-verify.o rsa-checksum.o
> >> +obj-$(CONFIG_$(SPL_)FIT_SIGNATURE) += rsa-verify.o rsa-checksum.o
> >>  obj-$(CONFIG_RSA_SOFTWARE_EXP) += rsa-mod-exp.o
> >> --
> >> 2.7.4
> 
> 
> Take care!
> --
> Teddy Reed V

Sorry for late response. I will try to rebase my patches using this patch. Also let me
know should I send those patches in parallel with this patch or wait for acceptance of
this patch?

Best regards,
Sumit


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