[PATCH 0/5] Enable ECDSA FIT verification for stm32mp

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[PATCH 0/5] Enable ECDSA FIT verification for stm32mp

Alexandru Gagniuc-2
This series is Part II of the ECDSA saga. It applies on top of [1]:
 * [PATCH v4 0/6] Add support for ECDSA image signing (with test)

I've designed the UCLASS_ECDSA such that it aligns with the ROM API
of the stm32mp. Instead of splitting the verification into
(1) curve operations and (2) modular exponentiation, I've
concatenated everything in a 'verify' step. It would be impossible to
split the steps and use the stm32mp ROM for verification.

Should more granular control be required, this API could be extended
at a later time. Until we have more hardware supporting ECDSA, this
is purely speculative.

The ROM API of the stm32mp is passed in 'r0' when the FSBL is called.
While we can save 'r0' in SPL, this series does not implement a
mechanism to pass this to u-boot. Thus the ROM API, and ECDSA
verification are only available for SPL. Although extending this to
u-boot by adding the ROM address to the FDT blob, implementing and
verifying this is beyond the scope of this series.

[1] https://lists.denx.de/pipermail/u-boot/2021-January/436935.html

Alexandru Gagniuc (5):
  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

 arch/arm/mach-stm32mp/Kconfig        |   9 ++
 arch/arm/mach-stm32mp/Makefile       |   1 +
 arch/arm/mach-stm32mp/ecdsa_romapi.c | 106 ++++++++++++++++++++++
 common/Kconfig.boot                  |   8 +-
 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 +++++++++++++++++++++++++++
 13 files changed, 320 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

--
2.26.2

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[PATCH 1/5] dm: crypto: Define UCLASS API for ECDSA signature verification

Alexandru Gagniuc-2
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 <[hidden email]>
---
 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 <[hidden email]>
+ */
+
+#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 e952a9967c..de4f5db086 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -45,6 +45,7 @@ enum uclass_id {
  UCLASS_DISPLAY, /* Display (e.g. DisplayPort, HDMI) */
  UCLASS_DSI_HOST, /* Display Serial Interface host */
  UCLASS_DMA, /* Direct Memory Access */
+ UCLASS_ECDSA, /* Elliptic curve cryptographic device */
  UCLASS_EFI, /* EFI managed devices */
  UCLASS_ETH, /* Ethernet device */
  UCLASS_ETH_PHY, /* Ethernet PHY device */
--
2.26.2

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[PATCH 2/5] lib: ecdsa: Add skeleton to implement ecdsa verification in u-boot

Alexandru Gagniuc-2
In reply to this post by Alexandru Gagniuc-2
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 <[hidden email]>
---
 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 6628173dca..1d70ba0ece 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1198,20 +1198,20 @@ 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
 
@@ -1260,7 +1260,7 @@ 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 7673d2e4e0..e2cb846fc0 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -292,6 +292,7 @@ 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 cf64188ba5..ab86be2678 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-$(CONFIG_SHA1) += sha1.o
diff --git a/lib/ecdsa/Kconfig b/lib/ecdsa/Kconfig
new file mode 100644
index 0000000000..1244d6b6ea
--- /dev/null
+++ b/lib/ecdsa/Kconfig
@@ -0,0 +1,23 @@
+config ECDSA
+ bool "Enable ECDSA support"
+ depends on DM
+ help
+  This enables the ECDSA algorithm for FIT image verification in U-Boot.
+  See doc/uImage.FIT/signature.txt for more details.
+  The ECDSA algorithm is implemented using the driver model. So
+  CONFIG_DM is required by this library.
+  ECDSA is enabled for mkimage regardless of this  option.
+
+if ECDSA
+
+config ECDSA_VERIFY
+ bool "Enable ECDSA verification support in U-Boot."
+ help
+  Allow ECDSA signatures to be recognized and verified in U-Boot.
+
+config SPL_ECDSA_VERIFY
+ bool "Enable ECDSA verification support in SPL"
+ help
+  Allow ECDSA signatures to be recognized and verified in SPL.
+
+endif
diff --git a/lib/ecdsa/Makefile b/lib/ecdsa/Makefile
new file mode 100644
index 0000000000..771d6d3135
--- /dev/null
+++ b/lib/ecdsa/Makefile
@@ -0,0 +1 @@
+obj-$(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 <[hidden email]>
+ */
+
+#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;
+}
--
2.26.2

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[PATCH 3/5] lib: ecdsa: Implement signature verification for crypto_algo API

Alexandru Gagniuc-2
In reply to this post by Alexandru Gagniuc-2
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 <[hidden email]>
---
 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..d84f6eb093 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 <[hidden email]>
  */
 
+#include <dm/uclass.h>
 #include <u-boot/ecdsa.h>
+#include <crypto/ecdsa-uclass.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 == 0)
+ 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(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",
+};
--
2.26.2

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[PATCH 4/5] arm: stm32mp1: Implement ECDSA signature verification

Alexandru Gagniuc-2
In reply to this post by Alexandru Gagniuc-2
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 <[hidden email]>
---
 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 f538d7cb83..f1e00929fd 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_STM32PROG
  bool "command stm32prog for STM32CudeProgrammer"
  select DFU
diff --git a/arch/arm/mach-stm32mp/Makefile b/arch/arm/mach-stm32mp/Makefile
index c8aa24d489..c03fedb486 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-$(CONFIG_STM32_ECDSA_VERIFY) += ecdsa_romapi.o
 else
 obj-$(CONFIG_CMD_STM32PROG) += 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..7f71d7a341
--- /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 != 32 || 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_DEVICE(stm32mp_rom_api_ecdsa) = {
+ .name = "stm32mp_rom_api_ecdsa",
+};
--
2.26.2

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

Alexandru Gagniuc-2
In reply to this post by Alexandru Gagniuc-2
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 <[hidden email]>
---
 common/Kconfig.boot | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/common/Kconfig.boot b/common/Kconfig.boot
index 3f6d9c1a25..280476698d 100644
--- a/common/Kconfig.boot
+++ b/common/Kconfig.boot
@@ -67,8 +67,8 @@ 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
  help
   This option enables signature verification of FIT uImages,
@@ -159,8 +159,8 @@ 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
 
 config SPL_LOAD_FIT
--
2.26.2

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Re: [PATCH 3/5] lib: ecdsa: Implement signature verification for crypto_algo API

Simon Glass-3
In reply to this post by Alexandru Gagniuc-2
On Mon, 11 Jan 2021 at 08:41, Alexandru Gagniuc <[hidden email]> wrote:

>
> 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 <[hidden email]>
> ---
>  lib/ecdsa/ecdsa-verify.c | 117 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 116 insertions(+), 1 deletion(-)

Reviewed-by: Simon Glass <[hidden email]>
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Re: [PATCH 1/5] dm: crypto: Define UCLASS API for ECDSA signature verification

Simon Glass-3
In reply to this post by Alexandru Gagniuc-2
Hi Alexandru,

On Mon, 11 Jan 2021 at 08:41, Alexandru Gagniuc <[hidden email]> wrote:

>
> 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 <[hidden email]>
> ---
>  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

This needs a test, as do all uclasses in U-Boot. If it isn't easy to
implement the algorithm then I suppose you could fake it by using an
easy algorithm like md5, but it does need a test.

Regards,
Simon
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Re: [PATCH 5/5] Kconfig: FIT_SIGNATURE should not select RSA_VERIFY

Simon Glass-3
In reply to this post by Alexandru Gagniuc-2
On Mon, 11 Jan 2021 at 08:41, Alexandru Gagniuc <[hidden email]> wrote:

>
> 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 <[hidden email]>
> ---
>  common/Kconfig.boot | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Simon Glass <[hidden email]>
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Re: [PATCH 1/5] dm: crypto: Define UCLASS API for ECDSA signature verification

Alexandru Gagniuc-2
In reply to this post by Simon Glass-3
On 1/13/21 10:10 AM, Simon Glass wrote:

> Hi Alexandru,
>
> On Mon, 11 Jan 2021 at 08:41, Alexandru Gagniuc <[hidden email]> wrote:
>>
>> 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 <[hidden email]>
>> ---
>>   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
>
> This needs a test, as do all uclasses in U-Boot. If it isn't easy to
> implement the algorithm then I suppose you could fake it by using an
> easy algorithm like md5, but it does need a test.

I agree. I couldn't find a test for UCLASS_MOD_EXP (for guidance), so
I'm not sure where to even start.

Alex

> Regards,
> Simon
>
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Re: [PATCH 1/5] dm: crypto: Define UCLASS API for ECDSA signature verification

Simon Glass-3
Hi Alex,

On Thu, 14 Jan 2021 at 09:09, Alex G. <[hidden email]> wrote:

>
> On 1/13/21 10:10 AM, Simon Glass wrote:
> > Hi Alexandru,
> >
> > On Mon, 11 Jan 2021 at 08:41, Alexandru Gagniuc <[hidden email]> wrote:
> >>
> >> 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 <[hidden email]>
> >> ---
> >>   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
> >
> > This needs a test, as do all uclasses in U-Boot. If it isn't easy to
> > implement the algorithm then I suppose you could fake it by using an
> > easy algorithm like md5, but it does need a test.
>
> I agree. I couldn't find a test for UCLASS_MOD_EXP (for guidance), so
> I'm not sure where to even start.

How about dm_test_rng_read()? That is pretty simple and does a few basic things.

Re UCLASS_MOD_EXP this is tested by the vboot tests. It should really
have a simple unit test too, though. This is an example of how to add
a software implementation of a hardware algorithm. See mod_exp_sw.c

Regards,
Simon