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- // 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)
- {
- 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",
- };
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