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@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Acked-by: Andreas Dannenberg <dannenberg@ti.com>
Acked-by: Sumit Garg <sumit.garg@nxp.com>

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

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

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/

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) = {

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-$(CONFIG_GZIP_COMPRESSED) += gzip.o
@@ -39,15 +36,17 @@ obj-y += net_utils.o
 obj-$(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-$(CONFIG_SHA256) += sha256.o
 obj-$(CONFIG_TPM) += tpm.o
 obj-$(CONFIG_RBTREE)	+= rbtree.o
 obj-$(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/

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"

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