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", +};