[U-Boot] [PATCH] RFC: Secure boot to U-Boot proper from SPL
Teddy Reed
teddy at prosauce.org
Mon May 23 19:53:35 CEST 2016
> On May 23, 2016, at 1:15 PM, Andreas Dannenberg <dannenberg at ti.com> wrote:
>
>> 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...
Definitely! My original goal was verified boot in SPL with a minimum set of configuration/code changes. I've been working in the code base for a few weeks now and absolutely agree that with a bit more code modifications the driver model requirement could removed.
I do love the concept of representing the EXP implementation as a uclass driver, but for highly constrained SPLs it's not the best.
I think it's a good idea to land the proposed minimum set of configuration changes required for verified boot in SPL. Then we can iterate together on removing the DM requirement. What do you think?
The main reason I suggest multiple patches is because the decoupling may also affect non-SPL verified boots. :)
Take care!
-Teddy
>
> 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
>> _______________________________________________
>> U-Boot mailing list
>> U-Boot at lists.denx.de
>> http://lists.denx.de/mailman/listinfo/u-boot
More information about the U-Boot
mailing list