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https://github.com/AsahiLinux/u-boot
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928a8be794
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> Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* ECDSA signature verification for u-boot
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*
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* This implements the firmware-side wrapper for ECDSA verification. It bridges
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* the struct crypto_algo API to the ECDSA uclass implementations.
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*
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* Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
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*/
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#include <crypto/ecdsa-uclass.h>
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#include <dm/uclass.h>
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#include <u-boot/ecdsa.h>
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/*
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* Derive size of an ECDSA key from the curve name
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*
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* While it's possible to extract the key size by using string manipulation,
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* use a list of known curves for the time being.
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*/
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static int ecdsa_key_size(const char *curve_name)
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{
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if (!strcmp(curve_name, "prime256v1"))
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return 256;
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else
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return 0;
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}
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static int fdt_get_key(struct ecdsa_public_key *key, const void *fdt, int node)
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{
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int x_len, y_len;
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key->curve_name = fdt_getprop(fdt, node, "ecdsa,curve", NULL);
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key->size_bits = ecdsa_key_size(key->curve_name);
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if (key->size_bits == 0) {
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debug("Unknown ECDSA curve '%s'", key->curve_name);
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return -EINVAL;
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}
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key->x = fdt_getprop(fdt, node, "ecdsa,x-point", &x_len);
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key->y = fdt_getprop(fdt, node, "ecdsa,y-point", &y_len);
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if (!key->x || !key->y)
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return -EINVAL;
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if (x_len != (key->size_bits / 8) || y_len != (key->size_bits / 8)) {
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printf("%s: node=%d, curve@%p x@%p+%i y@%p+%i\n", __func__,
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node, key->curve_name, key->x, x_len, key->y, y_len);
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return -EINVAL;
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}
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return 0;
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}
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static int ecdsa_verify_hash(struct udevice *dev,
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const struct image_sign_info *info,
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const void *hash, const void *sig, uint sig_len)
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{
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const struct ecdsa_ops *ops = device_get_ops(dev);
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const struct checksum_algo *algo = info->checksum;
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struct ecdsa_public_key key;
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int sig_node, key_node, ret;
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if (!ops || !ops->verify)
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return -ENODEV;
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if (info->required_keynode > 0) {
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ret = fdt_get_key(&key, info->fdt_blob, info->required_keynode);
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if (ret < 0)
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return ret;
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return ops->verify(dev, &key, hash, algo->checksum_len,
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sig, sig_len);
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}
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sig_node = fdt_subnode_offset(info->fdt_blob, 0, FIT_SIG_NODENAME);
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if (sig_node < 0)
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return -ENOENT;
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/* Try all possible keys under the "/signature" node */
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fdt_for_each_subnode(key_node, info->fdt_blob, sig_node) {
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ret = fdt_get_key(&key, info->fdt_blob, key_node);
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if (ret < 0)
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continue;
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ret = ops->verify(dev, &key, hash, algo->checksum_len,
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sig, sig_len);
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/* On success, don't worry about remaining keys */
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if (!ret)
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return 0;
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}
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return -EPERM;
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}
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int ecdsa_verify(struct image_sign_info *info,
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const struct image_region region[], int region_count,
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uint8_t *sig, uint sig_len)
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{
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const struct checksum_algo *algo = info->checksum;
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uint8_t hash[algo->checksum_len];
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struct udevice *dev;
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int ret;
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ret = uclass_first_device_err(UCLASS_ECDSA, &dev);
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if (ret) {
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debug("ECDSA: Could not find ECDSA implementation: %d\n", ret);
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return ret;
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}
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ret = algo->calculate(algo->name, region, region_count, hash);
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if (ret < 0)
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return -EINVAL;
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return ecdsa_verify_hash(dev, info, hash, sig, sig_len);
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}
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U_BOOT_CRYPTO_ALGO(ecdsa) = {
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.name = "ecdsa256",
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.key_len = ECDSA256_BYTES,
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.verify = ecdsa_verify,
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};
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/*
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* uclass definition for ECDSA API
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*
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* We don't implement any wrappers around ecdsa_ops->verify() because it's
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* trivial to call ops->verify().
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*/
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UCLASS_DRIVER(ecdsa) = {
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.id = UCLASS_ECDSA,
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.name = "ecdsa_verifier",
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};
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