[U-Boot] [PATCH] RFC: Secure boot to U-Boot proper from SPL
Andreas Dannenberg
dannenberg at ti.com
Mon May 23 19:15:39 CEST 2016
On Sun, May 08, 2016 at 06:13:50PM -0700, Teddy Reed wrote:
> On Sun, May 1, 2016 at 11:12 AM, Teddy Reed <teddy.reed at gmail.com> wrote:
> > I've been using the following patch for my configurations, please excuse the top-posting. I think the only difference is enabling the uclass mod_exp driver to initialize without needing relocation.
> >
>
> If no one has any additional notes / requirements for enablement in
> SPL I can send my tiny bit of configuration changes as a patch.
>
> I've tested the DM flag change for the RSA mod_exp driver class for
> both relocated (u-boot) and non-relocated (SPL) builds and found no
> issues. It would be awesome to get another set of eyes on the Makefile
> feature reorganization as I don't want this to include unneeded code
> into SPLs. :)
Hi Teddy,
I was just trying to work your patch into my U-Boot tree to experiment
with it some when I realized that it requires CONFIG_SPL_DM which is
something the platforms I work with don't currently support :(
I'll need to look further and see what I can do about it (using the
non-DM rsa_mod_exp_sw routine instead of rsa_mod_exp?) but generally
speaking it seems like that non-DM based authentication could be a
useful feature for SPL, since one big reason of using an SPL in the
first place is to have something that fits into the minimum amount of
on-chip RAM possible...
Thanks and Regards,
--
Andreas Dannenberg
Texas Instruments Inc
> > 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 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>
> > ---
> > Kconfig | 11 +++++++++++
> > common/Makefile | 1 +
> > drivers/Makefile | 1 +
> > drivers/crypto/rsa_mod_exp/mod_exp_sw.c | 1 +
> > lib/Makefile | 9 +++++----
> > lib/rsa/Kconfig | 3 +++
> > lib/rsa/Makefile | 2 +-
> > 7 files changed, 23 insertions(+), 5 deletions(-)
> >
> > diff --git a/Kconfig b/Kconfig
> > index f53759a..e73ad03 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 b23f312..271f633 100644
> > --- a/common/Makefile
> > +++ b/common/Makefile
> > @@ -91,6 +91,7 @@ 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-$(CONFIG_SPL_NET_SUPPORT) += miiphyutil.o
> > diff --git a/drivers/Makefile b/drivers/Makefile
> > index 6900097..456492f 100644
> > --- a/drivers/Makefile
> > +++ b/drivers/Makefile
> > @@ -10,6 +10,7 @@ obj-$(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-$(CONFIG_SPL_MMC_SUPPORT) += mmc/
> > diff --git a/drivers/crypto/rsa_mod_exp/mod_exp_sw.c b/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> > index dc6c064..56d7e89 100644
> > --- a/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> > +++ b/drivers/crypto/rsa_mod_exp/mod_exp_sw.c
> > @@ -32,6 +32,7 @@ U_BOOT_DRIVER(mod_exp_sw) = {
> > .name = "mod_exp_sw",
> > .id = UCLASS_MOD_EXP,
> > .ops = &mod_exp_ops_sw,
> > + .flags = DM_FLAG_PRE_RELOC,
> > };
> >
> > U_BOOT_DEVICE(mod_exp_sw) = {
> > diff --git a/lib/Makefile b/lib/Makefile
> > index 02dfa29..5c83e32 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -9,7 +9,6 @@ ifndef CONFIG_SPL_BUILD
> >
> > obj-$(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
> > @@ -41,7 +38,6 @@ 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-$(CONFIG_RBTREE) += rbtree.o
> > @@ -49,6 +45,11 @@ obj-$(CONFIG_BITREVERSE) += bitrev.o
> > obj-y += list_sort.o
> > endif
> >
> > +obj-$(CONFIG_$(SPL_)OF_CONTROL) += fdtdec_common.o
> > +obj-$(CONFIG_$(SPL_)OF_CONTROL) += fdtdec.o
> > +obj-$(CONFIG_$(SPL_)RSA) += rsa/
> > +obj-$(CONFIG_$(SPL_)SHA256) += sha256.o
> > +
> > obj-$(CONFIG_$(SPL_)OF_LIBFDT) += libfdt/
> > ifdef CONFIG_SPL_OF_CONTROL
> > obj-$(CONFIG_OF_LIBFDT) += libfdt/
> > diff --git a/lib/rsa/Kconfig b/lib/rsa/Kconfig
> > index 86df0a0..ec80e43 100644
> > --- a/lib/rsa/Kconfig
> > +++ b/lib/rsa/Kconfig
> > @@ -13,6 +13,9 @@ config RSA
> > option. The software based modular exponentiation is built into
> > mkimage irrespective of this option.
> >
> > +config SPL_RSA
> > + bool "Use RSA Library within SPL"
> > +
> > if RSA
> > config RSA_SOFTWARE_EXP
> > bool "Enable driver for RSA Modular Exponentiation in software"
> > diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile
> > index 6867e50..4b2c1ba 100644
> > --- a/lib/rsa/Makefile
> > +++ b/lib/rsa/Makefile
> > @@ -7,5 +7,5 @@
> > # SPDX-License-Identifier: GPL-2.0+
> > #
> >
> > -obj-$(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
> > --
> > 1.9.1
> >
> >
> >
> > On Sun, 1 May 2016 11:45:22 -0600
> > Simon Glass <sjg at chromium.org> wrote:
> >
> >> For those that have asked me about this, I have dug into the past and cannot
> >> find my experiment. In the end I managed to reduce U-Boot proper down to
> >> about 100KB of code (by dropping CONFIG_CMD and removing video and USB
> >> drivers) and this was small enough to fit in SRAM. So SPL was not needed.
> >>
> >> That said, my experiment drove a lot of the FIT and image refactoring and
> >> I think it is actually pretty easy now to enable the full FIT implementation
> >> in SPL, if your SoC limitations allow it.
> >>
> >> In the case of Chrome OS, both U-Boot SPL and U-Boot proper are in read-only
> >> memory so there is no need for this. But even then it is useful to be able
> >> to have the smallest amount of non-updateable software, so quite a bit of
> >> work was done (for pit/pi) to support loading a read-write 'U-Boot proper'
> >> from SPL.
> >>
> >> So I think it would be useful to support loading and verifying FIT images
> >> with public key encryption in U-Boot, and fairly straightforward.
> >>
> >> To help things along, here is a starting point for firefly-rk3288 (Thumb 2).
> >> This board already uses device tree in SPL (perhaps bravely given the SoC
> >> size limitations) so the additional code would be a few KB larger for
> >> platforms that don't.
> >>
> >> For firefly the code size increases from 26KB to 40 KB. There is a fair bit
> >> of opportunity to reduce this if needed, for example by cutting out strings.
> >>
> >> Please reply on this thread if you plan to pick this up and prepare a series
> >> to enable this in U-Boot, to reduce duplicated work.
> >> Signed-off-by: Simon Glass <sjg at chromium.org>
> >> ---
> >>
> >> Kconfig | 8 ++++++++
> >> common/Makefile | 3 ++-
> >> common/image-fit.c | 2 +-
> >> common/spl/spl.c | 1 +
> >> configs/firefly-rk3288_defconfig | 5 +++++
> >> drivers/Makefile | 1 +
> >> include/configs/rk3288_common.h | 2 ++
> >> lib/Makefile | 3 ++-
> >> lib/rsa/rsa-verify.c | 5 ++++-
> >> 9 files changed, 26 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/Kconfig b/Kconfig
> >> index f53759a..4ffcc76 100644
> >> --- a/Kconfig
> >> +++ b/Kconfig
> >> @@ -183,6 +183,10 @@ config FIT
> >> verified boot (secure boot using RSA). This option enables that
> >> feature.
> >>
> >> +config SPL_FIT
> >> + bool "Support Flattened Image Tree in SPL"
> >> + depends on FIT
> >> +
> >> config FIT_VERBOSE
> >> bool "Display verbose messages on FIT boot"
> >> depends on FIT
> >> @@ -205,6 +209,10 @@ 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 uImages in SPL"
> >> + depends on FIT_SIGNATURE
> >> +
> >> 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 b23f312..647a4ed 100644
> >> --- a/common/Makefile
> >> +++ b/common/Makefile
> >> @@ -10,7 +10,6 @@ ifndef CONFIG_SPL_BUILD
> >> obj-y += init/
> >> obj-y += main.o
> >> obj-y += exports.o
> >> -obj-y += hash.o
> >> ifdef CONFIG_SYS_HUSH_PARSER
> >> obj-y += cli_hush.o
> >> endif
> >> @@ -150,6 +149,8 @@ obj-y += fb_nand.o
> >> endif
> >> endif
> >>
> >> +obj-y += hash.o
> >> +
> >> # We always have this since drivers/ddr/fs/interactive.c needs it
> >> obj-$(CONFIG_CMDLINE) += cli_simple.o
> >>
> >> diff --git a/common/image-fit.c b/common/image-fit.c
> >> index 25f8a11..12c94e1 100644
> >> --- a/common/image-fit.c
> >> +++ b/common/image-fit.c
> >> @@ -1502,7 +1502,7 @@ void fit_conf_print(const void *fit, int noffset, const char *p)
> >>
> >> static int fit_image_select(const void *fit, int rd_noffset, int verify)
> >> {
> >> - fit_image_print(fit, rd_noffset, " ");
> >> +// fit_image_print(fit, rd_noffset, " ");
> >>
> >> if (verify) {
> >> puts(" Verifying Hash Integrity ... ");
> >> diff --git a/common/spl/spl.c b/common/spl/spl.c
> >> index 82e7f58..017ca82 100644
> >> --- a/common/spl/spl.c
> >> +++ b/common/spl/spl.c
> >> @@ -345,6 +345,7 @@ void board_init_r(gd_t *dummy1, ulong dummy2)
> >> int i;
> >>
> >> debug(">>spl:board_init_r()\n");
> >> + fit_image_load(NULL, 0, NULL, NULL, 0, 0, 0, 0, NULL, NULL);
> >>
> >> #if defined(CONFIG_SYS_SPL_MALLOC_START)
> >> mem_malloc_init(CONFIG_SYS_SPL_MALLOC_START,
> >> diff --git a/configs/firefly-rk3288_defconfig b/configs/firefly-rk3288_defconfig
> >> index 0995f9b..596475c 100644
> >> --- a/configs/firefly-rk3288_defconfig
> >> +++ b/configs/firefly-rk3288_defconfig
> >> @@ -69,3 +69,8 @@ CONFIG_USE_PRIVATE_LIBGCC=y
> >> CONFIG_USE_TINY_PRINTF=y
> >> CONFIG_CMD_DHRYSTONE=y
> >> CONFIG_ERRNO_STR=y
> >> +CONFIG_SPL_FIT=y
> >> +CONFIG_SPL_OF_LIBFDT
> >> +CONFIG_FIT_SIGNATURE=y
> >> +CONFIG_SPL_FIT_SIGNATURE=y
> >> +CONFIG_FIT=y
> >> diff --git a/drivers/Makefile b/drivers/Makefile
> >> index 6900097..baf9dee 100644
> >> --- a/drivers/Makefile
> >> +++ b/drivers/Makefile
> >> @@ -36,6 +36,7 @@ obj-$(CONFIG_SPL_WATCHDOG_SUPPORT) += watchdog/
> >> obj-$(CONFIG_SPL_USB_HOST_SUPPORT) += usb/host/
> >> obj-$(CONFIG_OMAP_USB_PHY) += usb/phy/
> >> obj-$(CONFIG_SPL_SATA_SUPPORT) += block/
> >> +obj-$(CONFIG_SPL_CRYPTO_SUPPORT) += crypto/
> >>
> >> else
> >>
> >> diff --git a/include/configs/rk3288_common.h b/include/configs/rk3288_common.h
> >> index 8a81397..39bffcb 100644
> >> --- a/include/configs/rk3288_common.h
> >> +++ b/include/configs/rk3288_common.h
> >> @@ -11,6 +11,8 @@
> >>
> >> #include <asm/arch/hardware.h>
> >>
> >> +#define CONFIG_SPL_CRYPTO_SUPPORT
> >> +
> >> #define CONFIG_SYS_NO_FLASH
> >> #define CONFIG_NR_DRAM_BANKS 1
> >> #define CONFIG_ENV_SIZE 0x2000
> >> diff --git a/lib/Makefile b/lib/Makefile
> >> index 02dfa29..b3ea4bd 100644
> >> --- a/lib/Makefile
> >> +++ b/lib/Makefile
> >> @@ -9,7 +9,6 @@ ifndef CONFIG_SPL_BUILD
> >>
> >> obj-$(CONFIG_EFI) += efi/
> >> obj-$(CONFIG_EFI_LOADER) += efi_loader/
> >> -obj-$(CONFIG_RSA) += rsa/
> >> obj-$(CONFIG_LZMA) += lzma/
> >> obj-$(CONFIG_LZO) += lzo/
> >> obj-$(CONFIG_ZLIB) += zlib/
> >> @@ -49,6 +48,8 @@ obj-$(CONFIG_BITREVERSE) += bitrev.o
> >> obj-y += list_sort.o
> >> endif
> >>
> >> +obj-$(CONFIG_RSA) += rsa/
> >> +
> >> obj-$(CONFIG_$(SPL_)OF_LIBFDT) += libfdt/
> >> ifdef CONFIG_SPL_OF_CONTROL
> >> obj-$(CONFIG_OF_LIBFDT) += libfdt/
> >> diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
> >> index 60126d2..341ce2e 100644
> >> --- a/lib/rsa/rsa-verify.c
> >> +++ b/lib/rsa/rsa-verify.c
> >> @@ -200,7 +200,10 @@ int rsa_verify(struct image_sign_info *info,
> >> }
> >>
> >> /* Look for a key that matches our hint */
> >> - snprintf(name, sizeof(name), "key-%s", info->keyname);
> >> + // FIXME
> >> + //snprintf(name, sizeof(name), "key-%s", info->keyname);
> >> + strcpy(name, "key-");
> >> + strcat(name, info->keyname);
> >> node = fdt_subnode_offset(blob, sig_node, name);
> >> ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
> >> if (!ret)
> >> --
> >> 2.8.0.rc3.226.g39d4020
> >>
>
> --
> Teddy Reed V
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