+// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2013, Google Inc.
- *
- * SPDX-License-Identifier: GPL-2.0+
*/
#ifndef USE_HOSTCC
/* Default public exponent for backward compatibility */
#define RSA_DEFAULT_PUBEXP 65537
+/**
+ * rsa_verify_padding() - Verify RSA message padding is valid
+ *
+ * Verify a RSA message's padding is consistent with PKCS1.5
+ * padding as described in the RSA PKCS#1 v2.1 standard.
+ *
+ * @msg: Padded message
+ * @pad_len: Number of expected padding bytes
+ * @algo: Checksum algo structure having information on DER encoding etc.
+ * @return 0 on success, != 0 on failure
+ */
+static int rsa_verify_padding(const uint8_t *msg, const int pad_len,
+ struct checksum_algo *algo)
+{
+ int ff_len;
+ int ret;
+
+ /* first byte must be 0x00 */
+ ret = *msg++;
+ /* second byte must be 0x01 */
+ ret |= *msg++ ^ 0x01;
+ /* next ff_len bytes must be 0xff */
+ ff_len = pad_len - algo->der_len - 3;
+ ret |= *msg ^ 0xff;
+ ret |= memcmp(msg, msg+1, ff_len-1);
+ msg += ff_len;
+ /* next byte must be 0x00 */
+ ret |= *msg++;
+ /* next der_len bytes must match der_prefix */
+ ret |= memcmp(msg, algo->der_prefix, algo->der_len);
+
+ return ret;
+}
+
/**
* rsa_verify_key() - Verify a signature against some data using RSA Key
*
* @sig: Signature
* @sig_len: Number of bytes in signature
* @hash: Pointer to the expected hash
- * @algo: Checksum algo structure having information on RSA padding etc.
+ * @key_len: Number of bytes in rsa key
+ * @algo: Checksum algo structure having information on DER encoding etc.
* @return 0 if verified, -ve on error
*/
static int rsa_verify_key(struct key_prop *prop, const uint8_t *sig,
const uint32_t sig_len, const uint8_t *hash,
- struct checksum_algo *algo)
+ const uint32_t key_len, struct checksum_algo *algo)
{
- const uint8_t *padding;
int pad_len;
int ret;
#if !defined(USE_HOSTCC)
return ret;
}
- padding = algo->rsa_padding;
- pad_len = algo->pad_len - algo->checksum_len;
+ pad_len = key_len - algo->checksum_len;
/* Check pkcs1.5 padding bytes. */
- if (memcmp(buf, padding, pad_len)) {
+ ret = rsa_verify_padding(buf, pad_len, algo);
+ if (ret) {
debug("In RSAVerify(): Padding check failed!\n");
return -EINVAL;
}
return -EFAULT;
}
- ret = rsa_verify_key(&prop, sig, sig_len, hash, info->algo->checksum);
+ ret = rsa_verify_key(&prop, sig, sig_len, hash,
+ info->crypto->key_len, info->checksum);
return ret;
}
{
const void *blob = info->fdt_blob;
/* Reserve memory for maximum checksum-length */
- uint8_t hash[info->algo->checksum->pad_len];
+ uint8_t hash[info->crypto->key_len];
int ndepth, noffset;
int sig_node, node;
char name[100];
* Verify that the checksum-length does not exceed the
* rsa-signature-length
*/
- if (info->algo->checksum->checksum_len >
- info->algo->checksum->pad_len) {
+ if (info->checksum->checksum_len >
+ info->crypto->key_len) {
debug("%s: invlaid checksum-algorithm %s for %s\n",
- __func__, info->algo->checksum->name, info->algo->name);
+ __func__, info->checksum->name, info->crypto->name);
return -EINVAL;
}
}
/* Calculate checksum with checksum-algorithm */
- ret = info->algo->checksum->calculate(info->algo->checksum->name,
+ ret = info->checksum->calculate(info->checksum->name,
region, region_count, hash);
if (ret < 0) {
debug("%s: Error in checksum calculation\n", __func__);