[PATCH v3 0/6] Enable ECDSA FIT verification for stm32mp

[PATCH v3 0/6] Enable ECDSA FIT verification for stm32mp

[Alexandru Gagniuc]

This series is Part II of the ECDSA saga. It applies on top of [1]:
 * [PATCH v7 00/11] Add support for ECDSA image signing

Changes since v2:
  - Spell out "elliptic curve" in Kconfig (Although RSA isn't spelled out)

Changes since v1:
  - Add test to make sure the UCLASS is enabled
  - Fix check against wrong sig_len in ecdsa_romapi.c
  - s/U_BOOT_DEVICE/U_BOOT_DRVINFO/
  - Use "if(!ret)" instead of "if (ret == 0)"
  - Use uclass_first_device_err() instead of uclass_first_device()
  - Make sure #includes are correctly alphabetized

Alexandru Gagniuc (6):
  dm: crypto: Define UCLASS API for ECDSA signature verification
  lib: ecdsa: Add skeleton to implement ecdsa verification in u-boot
  lib: ecdsa: Implement signature verification for crypto_algo API
  arm: stm32mp1: Implement ECDSA signature verification
  Kconfig: FIT_SIGNATURE should not select RSA_VERIFY
  test: dm: Add test for ECDSA UCLASS support

 arch/arm/mach-stm32mp/Kconfig        |   9 ++
 arch/arm/mach-stm32mp/Makefile       |   1 +
 arch/arm/mach-stm32mp/ecdsa_romapi.c | 106 ++++++++++++++++++++++
 common/Kconfig.boot                  |   8 +-
 configs/sandbox_defconfig            |   2 +
 include/crypto/ecdsa-uclass.h        |  39 ++++++++
 include/dm/uclass-id.h               |   1 +
 include/image.h                      |  10 +--
 include/u-boot/rsa.h                 |   2 +-
 lib/Kconfig                          |   1 +
 lib/Makefile                         |   1 +
 lib/ecdsa/Kconfig                    |  23 +++++
 lib/ecdsa/Makefile                   |   1 +
 lib/ecdsa/ecdsa-verify.c             | 128 +++++++++++++++++++++++++++
 test/dm/Makefile                     |   1 +
 test/dm/ecdsa.c                      |  38 ++++++++
 16 files changed, 361 insertions(+), 10 deletions(-)
 create mode 100644 arch/arm/mach-stm32mp/ecdsa_romapi.c
 create mode 100644 include/crypto/ecdsa-uclass.h
 create mode 100644 lib/ecdsa/Kconfig
 create mode 100644 lib/ecdsa/Makefile
 create mode 100644 lib/ecdsa/ecdsa-verify.c
 create mode 100644 test/dm/ecdsa.c

-- 
2.26.3

[PATCH v3 1/6] dm: crypto: Define UCLASS API for ECDSA signature verification

[Alexandru Gagniuc]

Define a UCLASS API for verifying ECDSA signatures. Unlike
UCLASS_MOD_EXP, which focuses strictly on modular exponentiation,
the ECDSA class focuses on verification. This is done so that it
better aligns with mach-specific implementations, such as stm32mp.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
 include/crypto/ecdsa-uclass.h | 39 +++++++++++++++++++++++++++++++++++
 include/dm/uclass-id.h        |  1 +
 2 files changed, 40 insertions(+)
 create mode 100644 include/crypto/ecdsa-uclass.h

diff --git a/include/crypto/ecdsa-uclass.h b/include/crypto/ecdsa-uclass.h
new file mode 100644
index 0000000000..189843820a
--- /dev/null
+++ b/include/crypto/ecdsa-uclass.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ */
+
+#include <dm/device.h>
+
+/**
+ * struct ecdsa_public_key - ECDSA public key properties
+ *
+ * The struct has pointers to the (x, y) curve coordinates to an ECDSA public
+ * key, as well as the name of the ECDSA curve. The size of the key is inferred
+ * from the 'curve_name'
+ */
+struct ecdsa_public_key {
+	const char *curve_name;	/* Name of curve, e.g. "prime256v1" */
+	const void *x;		/* x coordinate of public key */
+	const void *y;		/* y coordinate of public key */
+	unsigned int size_bits;	/* key size in bits, derived from curve name */
+};
+
+struct ecdsa_ops {
+	/**
+	 * Verify signature of hash against given public key
+	 *
+	 * @dev:	ECDSA Device
+	 * @pubkey:	ECDSA public key
+	 * @hash:	Hash of binary image
+	 * @hash_len:	Length of hash in bytes
+	 * @signature:	Signature in a raw (R, S) point pair
+	 * @sig_len:	Length of signature in bytes
+	 *
+	 * This function verifies that the 'signature' of the given 'hash' was
+	 * signed by the private key corresponding to 'pubkey'.
+	 */
+	int (*verify)(struct udevice *dev, const struct ecdsa_public_key *pubkey,
+		      const void *hash, size_t hash_len,
+		      const void *signature, size_t sig_len);
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index d75de368c5..f335f4e5a4 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -47,6 +47,7 @@ enum uclass_id {
 	UCLASS_DSI_HOST,	/* Display Serial Interface host */
 	UCLASS_DMA,		/* Direct Memory Access */
 	UCLASS_DSA,		/* Distributed (Ethernet) Switch Architecture */
+	UCLASS_ECDSA,		/* Elliptic curve cryptographic device */
 	UCLASS_EFI,		/* EFI managed devices */
 	UCLASS_ETH,		/* Ethernet device */
 	UCLASS_ETH_PHY,		/* Ethernet PHY device */
-- 
2.26.3

[PATCH v3 2/6] lib: ecdsa: Add skeleton to implement ecdsa verification in u-boot

[Alexandru Gagniuc]

Prepare the source tree for accepting implementations of the ECDSA
algorithm. This patch deals with the boring aspects of Makefiles and
Kconfig files.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
 include/image.h          | 10 +++++-----
 include/u-boot/rsa.h     |  2 +-
 lib/Kconfig              |  1 +
 lib/Makefile             |  1 +
 lib/ecdsa/Kconfig        | 23 +++++++++++++++++++++++
 lib/ecdsa/Makefile       |  1 +
 lib/ecdsa/ecdsa-verify.c | 13 +++++++++++++
 7 files changed, 45 insertions(+), 6 deletions(-)
 create mode 100644 lib/ecdsa/Kconfig
 create mode 100644 lib/ecdsa/Makefile
 create mode 100644 lib/ecdsa/ecdsa-verify.c

diff --git a/include/image.h b/include/image.h
index 32aa4d02a3..eb46943572 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1219,20 +1219,20 @@ int calculate_hash(const void *data, int data_len, const char *algo,
 #if defined(USE_HOSTCC)
 # if defined(CONFIG_FIT_SIGNATURE)
 #  define IMAGE_ENABLE_SIGN	1
-#  define IMAGE_ENABLE_VERIFY	1
+#  define IMAGE_ENABLE_VERIFY_RSA	1
 #  define IMAGE_ENABLE_VERIFY_ECDSA	1
 #  define FIT_IMAGE_ENABLE_VERIFY	1
 #  include <openssl/evp.h>
 # else
 #  define IMAGE_ENABLE_SIGN	0
-#  define IMAGE_ENABLE_VERIFY	0
+#  define IMAGE_ENABLE_VERIFY_RSA	0
 # define IMAGE_ENABLE_VERIFY_ECDSA	0
 #  define FIT_IMAGE_ENABLE_VERIFY	0
 # endif
 #else
 # define IMAGE_ENABLE_SIGN	0
-# define IMAGE_ENABLE_VERIFY		CONFIG_IS_ENABLED(RSA_VERIFY)
-# define IMAGE_ENABLE_VERIFY_ECDSA	0
+# define IMAGE_ENABLE_VERIFY_RSA	CONFIG_IS_ENABLED(RSA_VERIFY)
+# define IMAGE_ENABLE_VERIFY_ECDSA	CONFIG_IS_ENABLED(ECDSA_VERIFY)
 # define FIT_IMAGE_ENABLE_VERIFY	CONFIG_IS_ENABLED(FIT_SIGNATURE)
 #endif
 
@@ -1288,7 +1288,7 @@ struct image_region {
 	int size;
 };
 
-#if IMAGE_ENABLE_VERIFY
+#if FIT_IMAGE_ENABLE_VERIFY
 # include <u-boot/hash-checksum.h>
 #endif
 struct checksum_algo {
diff --git a/include/u-boot/rsa.h b/include/u-boot/rsa.h
index bed1c097c2..eb258fca4c 100644
--- a/include/u-boot/rsa.h
+++ b/include/u-boot/rsa.h
@@ -81,7 +81,7 @@ static inline int rsa_add_verify_data(struct image_sign_info *info,
 }
 #endif
 
-#if IMAGE_ENABLE_VERIFY
+#if IMAGE_ENABLE_VERIFY_RSA
 /**
  * rsa_verify_hash() - Verify a signature against a hash
  *
diff --git a/lib/Kconfig b/lib/Kconfig
index 7288340614..48895e4e4f 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -295,6 +295,7 @@ config AES
 	  supported by the algorithm but only a 128-bit key is supported at
 	  present.
 
+source lib/ecdsa/Kconfig
 source lib/rsa/Kconfig
 source lib/crypto/Kconfig
 
diff --git a/lib/Makefile b/lib/Makefile
index 1d4b7d3aad..de55914f52 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -59,6 +59,7 @@ endif
 
 obj-$(CONFIG_$(SPL_)ACPIGEN) += acpi/
 obj-$(CONFIG_$(SPL_)MD5) += md5.o
+obj-$(CONFIG_ECDSA) += ecdsa/
 obj-$(CONFIG_$(SPL_)RSA) += rsa/
 obj-$(CONFIG_FIT_SIGNATURE) += hash-checksum.o
 obj-$(CONFIG_SHA1) += sha1.o
diff --git a/lib/ecdsa/Kconfig b/lib/ecdsa/Kconfig
new file mode 100644
index 0000000000..a95c4ff581
--- /dev/null
+++ b/lib/ecdsa/Kconfig
@@ -0,0 +1,23 @@
+config ECDSA
+	bool "Enable ECDSA support"
+	depends on DM
+	help
+	  This enables the ECDSA (elliptic curve signature) algorithm for FIT
+	  image verification in U-Boot. The ECDSA algorithm is implemented
+	  using the driver model, so CONFIG_DM is required by this library.
+	  See doc/uImage.FIT/signature.txt for more details.
+	  ECDSA is enabled for mkimage regardless of this option.
+
+if ECDSA
+
+config ECDSA_VERIFY
+	bool "Enable ECDSA verification support in U-Boot."
+	help
+	  Allow ECDSA signatures to be recognized and verified in U-Boot.
+
+config SPL_ECDSA_VERIFY
+	bool "Enable ECDSA verification support in SPL"
+	help
+	  Allow ECDSA signatures to be recognized and verified in SPL.
+
+endif
diff --git a/lib/ecdsa/Makefile b/lib/ecdsa/Makefile
new file mode 100644
index 0000000000..771d6d3135
--- /dev/null
+++ b/lib/ecdsa/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_$(SPL_)ECDSA_VERIFY) += ecdsa-verify.o
diff --git a/lib/ecdsa/ecdsa-verify.c b/lib/ecdsa/ecdsa-verify.c
new file mode 100644
index 0000000000..d2e6a40f4a
--- /dev/null
+++ b/lib/ecdsa/ecdsa-verify.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ */
+
+#include <u-boot/ecdsa.h>
+
+int ecdsa_verify(struct image_sign_info *info,
+		 const struct image_region region[], int region_count,
+		 uint8_t *sig, uint sig_len)
+{
+	return -EOPNOTSUPP;
+}
-- 
2.26.3

[PATCH v3 3/6] lib: ecdsa: Implement signature verification for crypto_algo API

[Alexandru Gagniuc]

Implement the crypto_algo .verify() function for ecdsa256. Because
it backends on UCLASS_ECDSA, this change is focused on parsing the
keys from devicetree and passing this information to the specific
UCLASS driver.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---
 lib/ecdsa/ecdsa-verify.c | 117 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 116 insertions(+), 1 deletion(-)

diff --git a/lib/ecdsa/ecdsa-verify.c b/lib/ecdsa/ecdsa-verify.c
index d2e6a40f4a..3e55b14497 100644
--- a/lib/ecdsa/ecdsa-verify.c
+++ b/lib/ecdsa/ecdsa-verify.c
@@ -1,13 +1,128 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
+ * ECDSA signature verification for u-boot
+ *
+ * This implements the firmware-side wrapper for ECDSA verification. It bridges
+ * the struct crypto_algo API to the ECDSA uclass implementations.
+ *
  * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
  */
 
+#include <crypto/ecdsa-uclass.h>
+#include <dm/uclass.h>
 #include <u-boot/ecdsa.h>
 
+/*
+ * Derive size of an ECDSA key from the curve name
+ *
+ * While it's possible to extract the key size by using string manipulation,
+ * use a list of known curves for the time being.
+ */
+static int ecdsa_key_size(const char *curve_name)
+{
+	if (!strcmp(curve_name, "prime256v1"))
+		return 256;
+	else
+		return 0;
+}
+
+static int fdt_get_key(struct ecdsa_public_key *key, const void *fdt, int node)
+{
+	int x_len, y_len;
+
+	key->curve_name = fdt_getprop(fdt, node, "ecdsa,curve", NULL);
+	key->size_bits = ecdsa_key_size(key->curve_name);
+	if (key->size_bits == 0) {
+		debug("Unknown ECDSA curve '%s'", key->curve_name);
+		return -EINVAL;
+	}
+
+	key->x = fdt_getprop(fdt, node, "ecdsa,x-point", &x_len);
+	key->y = fdt_getprop(fdt, node, "ecdsa,y-point", &y_len);
+
+	if (!key->x || !key->y)
+		return -EINVAL;
+
+	if (x_len != (key->size_bits / 8) || y_len != (key->size_bits / 8)) {
+		printf("%s: node=%d, curve@%p x@%p+%i y@%p+%i\n", __func__,
+		       node, key->curve_name, key->x, x_len, key->y, y_len);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int ecdsa_verify_hash(struct udevice *dev,
+			     const struct image_sign_info *info,
+			     const void *hash, const void *sig, uint sig_len)
+{
+	const struct ecdsa_ops *ops = device_get_ops(dev);
+	const struct checksum_algo *algo = info->checksum;
+	struct ecdsa_public_key key;
+	int sig_node, key_node, ret;
+
+	if (!ops || !ops->verify)
+		return -ENODEV;
+
+	if (info->required_keynode > 0) {
+		ret = fdt_get_key(&key, info->fdt_blob, info->required_keynode);
+		if (ret < 0)
+			return ret;
+
+		return ops->verify(dev, &key, hash, algo->checksum_len,
+				   sig, sig_len);
+	}
+
+	sig_node = fdt_subnode_offset(info->fdt_blob, 0, FIT_SIG_NODENAME);
+	if (sig_node < 0)
+		return -ENOENT;
+
+	/* Try all possible keys under the "/signature" node */
+	fdt_for_each_subnode(key_node, info->fdt_blob, sig_node) {
+		ret = fdt_get_key(&key, info->fdt_blob, key_node);
+		if (ret < 0)
+			continue;
+
+		ret = ops->verify(dev, &key, hash, algo->checksum_len,
+				  sig, sig_len);
+
+		/* On success, don't worry about remaining keys */
+		if (!ret)
+			return 0;
+	}
+
+	return -EPERM;
+}
+
 int ecdsa_verify(struct image_sign_info *info,
 		 const struct image_region region[], int region_count,
 		 uint8_t *sig, uint sig_len)
 {
-	return -EOPNOTSUPP;
+	const struct checksum_algo *algo = info->checksum;
+	uint8_t hash[algo->checksum_len];
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_first_device_err(UCLASS_ECDSA, &dev);
+	if (ret) {
+		debug("ECDSA: Could not find ECDSA implementation: %d\n", ret);
+		return ret;
+	}
+
+	ret = algo->calculate(algo->name, region, region_count, hash);
+	if (ret < 0)
+		return -EINVAL;
+
+	return ecdsa_verify_hash(dev, info, hash, sig, sig_len);
 }
+
+/*
+ * uclass definition for ECDSA API
+ *
+ * We don't implement any wrappers around ecdsa_ops->verify() because it's
+ * trivial to call ops->verify().
+ */
+UCLASS_DRIVER(ecdsa) = {
+	.id		= UCLASS_ECDSA,
+	.name		= "ecdsa_verifier",
+};
-- 
2.26.3

[PATCH v3 4/6] arm: stm32mp1: Implement ECDSA signature verification

[Alexandru Gagniuc]

The STM32MP ROM provides several service. One of them is the ability
to verify ecdsa256 signatures. Hook the ROM API into the ECDSA uclass.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
 arch/arm/mach-stm32mp/Kconfig        |   9 +++
 arch/arm/mach-stm32mp/Makefile       |   1 +
 arch/arm/mach-stm32mp/ecdsa_romapi.c | 106 +++++++++++++++++++++++++++
 3 files changed, 116 insertions(+)
 create mode 100644 arch/arm/mach-stm32mp/ecdsa_romapi.c

diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
index 079d66a80c..92c4c5a7b0 100644
--- a/arch/arm/mach-stm32mp/Kconfig
+++ b/arch/arm/mach-stm32mp/Kconfig
@@ -121,6 +121,15 @@ config STM32_ETZPC
 	help
 	  Say y to enable STM32 Extended TrustZone Protection
 
+config STM32_ECDSA_VERIFY
+	bool "STM32 ECDSA verification via the ROM API"
+	depends on SPL_ECDSA_VERIFY
+	default y
+	help
+	  Say y to enable the uclass driver for ECDSA verification using the
+	  ROM API provided on STM32MP.
+	  The ROM API is only available during SPL for now.
+
 config CMD_STM32KEY
 	bool "command stm32key to fuse public key hash"
 	default y
diff --git a/arch/arm/mach-stm32mp/Makefile b/arch/arm/mach-stm32mp/Makefile
index aa39867080..0942092d8e 100644
--- a/arch/arm/mach-stm32mp/Makefile
+++ b/arch/arm/mach-stm32mp/Makefile
@@ -10,6 +10,7 @@ obj-y += bsec.o
 
 ifdef CONFIG_SPL_BUILD
 obj-y += spl.o
+obj-$(CONFIG_STM32_ECDSA_VERIFY) += ecdsa_romapi.o
 else
 obj-y += cmd_stm32prog/
 obj-$(CONFIG_CMD_STM32KEY) += cmd_stm32key.o
diff --git a/arch/arm/mach-stm32mp/ecdsa_romapi.c b/arch/arm/mach-stm32mp/ecdsa_romapi.c
new file mode 100644
index 0000000000..ca32925a12
--- /dev/null
+++ b/arch/arm/mach-stm32mp/ecdsa_romapi.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * STM32MP ECDSA verification via the ROM API
+ *
+ * Implements ECDSA signature verification via the STM32MP ROM.
+ */
+#include <asm/system.h>
+#include <dm/device.h>
+#include <linux/types.h>
+#include <u-boot/ecdsa.h>
+#include <crypto/ecdsa-uclass.h>
+#include <linux/libfdt.h>
+#include <dm/platdata.h>
+
+#define ROM_API_SUCCESS				0x77
+#define ROM_API_ECDSA_ALGO_PRIME_256V1		1
+#define ROM_API_ECDSA_ALGO_BRAINPOOL_256	2
+
+#define ROM_API_OFFSET_ECDSA_CHECK_KEY		0x5c
+#define ROM_API_OFFSET_ECDSA_VERIFY		0x60
+
+struct ecdsa_rom_api {
+	uint32_t (*ecdsa_check_key)(const void *pubkey_in, void *pubkey_out);
+	uint32_t (*ecdsa_verify_signature)(const void *hash, const void *pubkey,
+					   const void *signature,
+				    uint32_t ecc_algo);
+};
+
+/*
+ * Without forcing the ".data" section, this would get saved in ".bss". BSS
+ * will be cleared soon after, so it's not suitable.
+ */
+static uintptr_t rom_api_loc __section(".data");
+
+/*
+ * The ROM gives us the API location in r0 when starting. This is only available
+ * during SPL, as there isn't (yet) a mechanism to pass this on to u-boot.
+ */
+void save_boot_params(unsigned long r0, unsigned long r1, unsigned long r2,
+		      unsigned long r3)
+{
+	rom_api_loc = r0;
+	save_boot_params_ret();
+}
+
+static void stm32mp_rom_get_ecdsa_functions(struct ecdsa_rom_api *rom)
+{
+	uintptr_t verify_ptr = rom_api_loc + ROM_API_OFFSET_ECDSA_VERIFY;
+	uintptr_t check_key_ptr = rom_api_loc + ROM_API_OFFSET_ECDSA_CHECK_KEY;
+
+	rom->ecdsa_verify_signature = *(void **)verify_ptr;
+	rom->ecdsa_check_key = *(void **)check_key_ptr;
+}
+
+static int ecdsa_key_algo(const char *curve_name)
+{
+	if (!strcmp(curve_name, "prime256v1"))
+		return ROM_API_ECDSA_ALGO_PRIME_256V1;
+	else if (!strcmp(curve_name, "brainpool256"))
+		return ROM_API_ECDSA_ALGO_BRAINPOOL_256;
+	else
+		return -ENOPROTOOPT;
+}
+
+static int romapi_ecdsa_verify(struct udevice *dev,
+			       const struct ecdsa_public_key *pubkey,
+			       const void *hash, size_t hash_len,
+			       const void *signature, size_t sig_len)
+{
+	struct ecdsa_rom_api rom;
+	uint8_t raw_key[64];
+	uint32_t rom_ret;
+	int algo;
+
+	/* The ROM API can only handle 256-bit ECDSA keys. */
+	if (sig_len != 64 || hash_len != 32 || pubkey->size_bits != 256)
+		return -EINVAL;
+
+	algo = ecdsa_key_algo(pubkey->curve_name);
+	if (algo < 0)
+		return algo;
+
+	/* The ROM API wants the (X, Y) coordinates concatenated. */
+	memcpy(raw_key, pubkey->x, 32);
+	memcpy(raw_key + 32, pubkey->y, 32);
+
+	stm32mp_rom_get_ecdsa_functions(&rom);
+	rom_ret = rom.ecdsa_verify_signature(hash, raw_key, signature, algo);
+
+	return rom_ret == ROM_API_SUCCESS ? 0 : -EPERM;
+}
+
+static const struct ecdsa_ops rom_api_ops = {
+	.verify = romapi_ecdsa_verify,
+};
+
+U_BOOT_DRIVER(stm32mp_rom_api_ecdsa) = {
+	.name	= "stm32mp_rom_api_ecdsa",
+	.id	= UCLASS_ECDSA,
+	.ops	= &rom_api_ops,
+	.flags	= DM_FLAG_PRE_RELOC,
+};
+
+U_BOOT_DRVINFO(stm32mp_rom_api_ecdsa) = {
+	.name = "stm32mp_rom_api_ecdsa",
+};
-- 
2.26.3

[PATCH v3 5/6] Kconfig: FIT_SIGNATURE should not select RSA_VERIFY

[Alexandru Gagniuc]

FIT signatures can now be implemented with ECDSA. The assumption that
all FIT images are signed with RSA is no longer valid. Thus, instead
of 'select'ing RSA, only 'imply' it. This doesn't change the defaults,
but allows one to explicitly disable RSA support.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---
 common/Kconfig.boot | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/common/Kconfig.boot b/common/Kconfig.boot
index 9c335f4f8c..788c287da2 100644
--- a/common/Kconfig.boot
+++ b/common/Kconfig.boot
@@ -76,8 +76,8 @@ config FIT_SIGNATURE
 	bool "Enable signature verification of FIT uImages"
 	depends on DM
 	select HASH
-	select RSA
-	select RSA_VERIFY
+	imply RSA
+	imply RSA_VERIFY
 	select IMAGE_SIGN_INFO
 	select FIT_FULL_CHECK
 	help
@@ -186,8 +186,8 @@ config SPL_FIT_SIGNATURE
 	select SPL_FIT
 	select SPL_CRYPTO_SUPPORT
 	select SPL_HASH_SUPPORT
-	select SPL_RSA
-	select SPL_RSA_VERIFY
+	imply SPL_RSA
+	imply SPL_RSA_VERIFY
 	select SPL_IMAGE_SIGN_INFO
 	select SPL_FIT_FULL_CHECK
 
-- 
2.26.3

[PATCH v3 6/6] test: dm: Add test for ECDSA UCLASS support

[Alexandru Gagniuc]

This test verifies that ECDSA_UCLASS is implemented, and that
ecdsa_verify() works as expected. The definition of "expected" is
"does not find a device, and returns -ENODEV".

The lack of a hardware-independent ECDSA implementation prevents us
from having one in the sandbox, for now.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
 configs/sandbox_defconfig |  2 ++
 test/dm/Makefile          |  1 +
 test/dm/ecdsa.c           | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+)
 create mode 100644 test/dm/ecdsa.c

diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 5bc90d09a8..bb73cab18d 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -283,3 +283,5 @@ CONFIG_TEST_FDTDEC=y
 CONFIG_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
+CONFIG_ECDSA=y
+CONFIG_ECDSA_VERIFY=y
diff --git a/test/dm/Makefile b/test/dm/Makefile
index fd1455109d..7d1870f941 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_CLK) += clk.o clk_ccf.o
 obj-$(CONFIG_CROS_EC) += cros_ec.o
 obj-$(CONFIG_DEVRES) += devres.o
 obj-$(CONFIG_VIDEO_MIPI_DSI) += dsi_host.o
+obj-$(CONFIG_ECDSA_VERIFY) += ecdsa.o
 obj-$(CONFIG_DM_ETH) += eth.o
 obj-$(CONFIG_FIRMWARE) += firmware.o
 obj-$(CONFIG_DM_GPIO) += gpio.o
diff --git a/test/dm/ecdsa.c b/test/dm/ecdsa.c
new file mode 100644
index 0000000000..23d57dd47f
--- /dev/null
+++ b/test/dm/ecdsa.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <crypto/ecdsa-uclass.h>
+#include <dm.h>
+#include <dm/test.h>
+#include <test/ut.h>
+#include <u-boot/ecdsa.h>
+
+/*
+ * Basic test of the ECDSA uclass and ecdsa_verify()
+ *
+ * ECDSA implementations in u-boot are hardware-dependent. Until we have a
+ * software implementation that can be compiled into the sandbox, all we can
+ * test is the uclass support.
+ *
+ * The uclass_get() test is redundant since ecdsa_verify() would also fail. We
+ * run both functions in order to isolate the cause more clearly. i.e. is
+ * ecdsa_verify() failing because the UCLASS is absent/broken?
+ */
+static int dm_test_ecdsa_verify(struct unit_test_state *uts)
+{
+	const struct ecdsa_ops *ops;
+	struct uclass *ucp;
+
+	const struct checksum_algo algo = {
+		.checksum_len = 256,
+	};
+
+	struct image_sign_info info = {
+		.checksum = &algo,
+	};
+
+	ut_assertok(uclass_get(UCLASS_ECDSA, &ucp));
+	ut_assertnonnull(ucp);
+	ut_assert(ecdsa_verify(&info, NULL, 0, NULL, 0) == -ENODEV);
+	return 0;
+}
+DM_TEST(dm_test_ecdsa_verify, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
-- 
2.26.3

[PATCH v3 4/6] arm: stm32mp1: Implement ECDSA signature verification

[Patrick DELAUNAY]

Hi,

On 3/30/21 8:32 PM, Alexandru Gagniuc wrote:
> The STM32MP ROM provides several service. One of them is the ability
> to verify ecdsa256 signatures. Hook the ROM API into the ECDSA uclass.
>
> Signed-off-by: Alexandru Gagniuc<mr.nuke.me@gmail.com>
> ---
>   arch/arm/mach-stm32mp/Kconfig        |   9 +++
>   arch/arm/mach-stm32mp/Makefile       |   1 +
>   arch/arm/mach-stm32mp/ecdsa_romapi.c | 106 +++++++++++++++++++++++++++
>   3 files changed, 116 insertions(+)
>   create mode 100644 arch/arm/mach-stm32mp/ecdsa_romapi.c
>
> diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
> index 079d66a80c..92c4c5a7b0 100644
> --- a/arch/arm/mach-stm32mp/Kconfig
> +++ b/arch/arm/mach-stm32mp/Kconfig
> @@ -121,6 +121,15 @@ config STM32_ETZPC
>   	help
>   	  Say y to enable STM32 Extended TrustZone Protection
>   
> +config STM32_ECDSA_VERIFY
> +	bool "STM32 ECDSA verification via the ROM API"
> +	depends on SPL_ECDSA_VERIFY
> +	default y
> +	help
> +	  Say y to enable the uclass driver for ECDSA verification using the
> +	  ROM API provided on STM32MP.
> +	  The ROM API is only available during SPL for now.
> +
>   config CMD_STM32KEY
>   	bool "command stm32key to fuse public key hash"
>   	default y
> diff --git a/arch/arm/mach-stm32mp/Makefile b/arch/arm/mach-stm32mp/Makefile
> index aa39867080..0942092d8e 100644
> --- a/arch/arm/mach-stm32mp/Makefile
> +++ b/arch/arm/mach-stm32mp/Makefile
> @@ -10,6 +10,7 @@ obj-y += bsec.o
>   
>   ifdef CONFIG_SPL_BUILD
>   obj-y += spl.o
> +obj-$(CONFIG_STM32_ECDSA_VERIFY) += ecdsa_romapi.o
>   else
>   obj-y += cmd_stm32prog/
>   obj-$(CONFIG_CMD_STM32KEY) += cmd_stm32key.o
> diff --git a/arch/arm/mach-stm32mp/ecdsa_romapi.c b/arch/arm/mach-stm32mp/ecdsa_romapi.c
> new file mode 100644
> index 0000000000..ca32925a12
> --- /dev/null
> +++ b/arch/arm/mach-stm32mp/ecdsa_romapi.c
> @@ -0,0 +1,106 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * STM32MP ECDSA verification via the ROM API
> + *
> + * Implements ECDSA signature verification via the STM32MP ROM.
> + */

#define LOG_CATEGORY UCLASS_ECDSA

to allow filtering with log command

> +#include <asm/system.h>
> +#include <dm/device.h>
> +#include <linux/types.h>
> +#include <u-boot/ecdsa.h>
> +#include <crypto/ecdsa-uclass.h>
> +#include <linux/libfdt.h>
> +#include <dm/platdata.h>
> +
> +#define ROM_API_SUCCESS				0x77
> +#define ROM_API_ECDSA_ALGO_PRIME_256V1		1
> +#define ROM_API_ECDSA_ALGO_BRAINPOOL_256	2
> +
> +#define ROM_API_OFFSET_ECDSA_CHECK_KEY		0x5c
> +#define ROM_API_OFFSET_ECDSA_VERIFY		0x60
> +
> +struct ecdsa_rom_api {
> +	uint32_t (*ecdsa_check_key)(const void *pubkey_in, void *pubkey_out);
> +	uint32_t (*ecdsa_verify_signature)(const void *hash, const void *pubkey,
> +					   const void *signature,
> +				    uint32_t ecc_algo);
> +};
> +
> +/*
> + * Without forcing the ".data" section, this would get saved in ".bss". BSS
> + * will be cleared soon after, so it's not suitable.
> + */
> +static uintptr_t rom_api_loc __section(".data");
> +
> +/*
> + * The ROM gives us the API location in r0 when starting. This is only available
> + * during SPL, as there isn't (yet) a mechanism to pass this on to u-boot.
> + */
> +void save_boot_params(unsigned long r0, unsigned long r1, unsigned long r2,
> +		      unsigned long r3)
> +{
> +	rom_api_loc = r0;
> +	save_boot_params_ret();
> +}
> +
> +static void stm32mp_rom_get_ecdsa_functions(struct ecdsa_rom_api *rom)
> +{
> +	uintptr_t verify_ptr = rom_api_loc + ROM_API_OFFSET_ECDSA_VERIFY;
> +	uintptr_t check_key_ptr = rom_api_loc + ROM_API_OFFSET_ECDSA_CHECK_KEY;
> +
> +	rom->ecdsa_verify_signature = *(void **)verify_ptr;
> +	rom->ecdsa_check_key = *(void **)check_key_ptr;


the check key API (rom->ecdsa_check_key at offset 
ROM_API_OFFSET_ECDSA_CHECK_KEY)

is never used...

   

Do you plan to use it in futures patches ?

if no, you can remove it.

PS: this API is no more used in recent TF-A downstrean version based on 
auth-framework


> +}
> +
> +static int ecdsa_key_algo(const char *curve_name)
> +{
> +	if (!strcmp(curve_name, "prime256v1"))
> +		return ROM_API_ECDSA_ALGO_PRIME_256V1;
> +	else if (!strcmp(curve_name, "brainpool256"))
> +		return ROM_API_ECDSA_ALGO_BRAINPOOL_256;
> +	else
> +		return -ENOPROTOOPT;
> +}
> +
> +static int romapi_ecdsa_verify(struct udevice *dev,
> +			       const struct ecdsa_public_key *pubkey,
> +			       const void *hash, size_t hash_len,
> +			       const void *signature, size_t sig_len)
> +{
> +	struct ecdsa_rom_api rom;
> +	uint8_t raw_key[64];
> +	uint32_t rom_ret;
> +	int algo;
> +
> +	/* The ROM API can only handle 256-bit ECDSA keys. */
> +	if (sig_len != 64 || hash_len != 32 || pubkey->size_bits != 256)
> +		return -EINVAL;
> +
> +	algo = ecdsa_key_algo(pubkey->curve_name);
> +	if (algo < 0)
> +		return algo;
> +
> +	/* The ROM API wants the (X, Y) coordinates concatenated. */
> +	memcpy(raw_key, pubkey->x, 32);
> +	memcpy(raw_key + 32, pubkey->y, 32);
> +
> +	stm32mp_rom_get_ecdsa_functions(&rom);
> +	rom_ret = rom.ecdsa_verify_signature(hash, raw_key, signature, algo);
> +
> +	return rom_ret == ROM_API_SUCCESS ? 0 : -EPERM;
> +}
> +
> +static const struct ecdsa_ops rom_api_ops = {
> +	.verify = romapi_ecdsa_verify,
> +};
> +
> +U_BOOT_DRIVER(stm32mp_rom_api_ecdsa) = {
> +	.name	= "stm32mp_rom_api_ecdsa",
> +	.id	= UCLASS_ECDSA,
> +	.ops	= &rom_api_ops,
> +	.flags	= DM_FLAG_PRE_RELOC,
> +};
> +
> +U_BOOT_DRVINFO(stm32mp_rom_api_ecdsa) = {
> +	.name = "stm32mp_rom_api_ecdsa",
> +};


Regards


Patrick