From 928a8be79480b0e2ea2461a7b2533d3e71bcb3e6 Mon Sep 17 00:00:00 2001 From: Alexandru Gagniuc Date: Thu, 29 Jul 2021 11:47:16 -0500 Subject: [PATCH] lib: ecdsa: Implement UCLASS_ECDSA verification on target 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 Reviewed-by: Simon Glass Reviewed-by: Patrick Delaunay --- lib/Kconfig | 1 + lib/Makefile | 1 + lib/ecdsa/Kconfig | 23 +++++++ lib/ecdsa/Makefile | 1 + lib/ecdsa/ecdsa-verify.c | 134 +++++++++++++++++++++++++++++++++++++++ 5 files changed, 160 insertions(+) create mode 100644 lib/ecdsa/Kconfig create mode 100644 lib/ecdsa/Makefile create mode 100644 lib/ecdsa/ecdsa-verify.c diff --git a/lib/Kconfig b/lib/Kconfig index 7b445d0164..c535147aea 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -303,6 +303,7 @@ 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 source lib/crypt/Kconfig diff --git a/lib/Makefile b/lib/Makefile index 07c2ccd7cf..8ba745faa0 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -60,6 +60,7 @@ endif obj-$(CONFIG_$(SPL_)ACPIGEN) += acpi/ obj-$(CONFIG_$(SPL_)MD5) += md5.o +obj-$(CONFIG_ECDSA) += ecdsa/ obj-$(CONFIG_$(SPL_)RSA) += rsa/ obj-$(CONFIG_HASH) += 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..0601700c4f --- /dev/null +++ b/lib/ecdsa/ecdsa-verify.c @@ -0,0 +1,134 @@ +// 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 + */ + +#include +#include +#include + +/* + * 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) +{ + 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); +} + +U_BOOT_CRYPTO_ALGO(ecdsa) = { + .name = "ecdsa256", + .key_len = ECDSA256_BYTES, + .verify = ecdsa_verify, +}; + +/* + * 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", +}; -- 2.39.5