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![AKASHI Takahiro](/assets/img/avatar_default.png)
This function will be used to implement public_key_verify_signature() in a later patch. rsa_verify() is not suitable here because calculation of message digest is not necessary. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
566 lines
14 KiB
C
566 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (c) 2013, Google Inc.
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*/
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#ifndef USE_HOSTCC
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#include <common.h>
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#include <fdtdec.h>
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#include <log.h>
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#include <malloc.h>
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#include <asm/types.h>
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#include <asm/byteorder.h>
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#include <linux/errno.h>
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#include <asm/types.h>
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#include <asm/unaligned.h>
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#include <dm.h>
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#else
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#include "fdt_host.h"
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#include "mkimage.h"
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#include <fdt_support.h>
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#endif
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#include <linux/kconfig.h>
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#include <u-boot/rsa-mod-exp.h>
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#include <u-boot/rsa.h>
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#ifndef __UBOOT__
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/*
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* NOTE:
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* Since host tools, like mkimage, make use of openssl library for
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* RSA encryption, rsa_verify_with_pkey()/rsa_gen_key_prop() are
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* of no use and should not be compiled in.
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* So just turn off CONFIG_RSA_VERIFY_WITH_PKEY.
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*/
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#undef CONFIG_RSA_VERIFY_WITH_PKEY
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#endif
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/* Default public exponent for backward compatibility */
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#define RSA_DEFAULT_PUBEXP 65537
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/**
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* rsa_verify_padding() - Verify RSA message padding is valid
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*
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* Verify a RSA message's padding is consistent with PKCS1.5
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* padding as described in the RSA PKCS#1 v2.1 standard.
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*
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* @msg: Padded message
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* @pad_len: Number of expected padding bytes
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* @algo: Checksum algo structure having information on DER encoding etc.
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* @return 0 on success, != 0 on failure
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*/
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static int rsa_verify_padding(const uint8_t *msg, const int pad_len,
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struct checksum_algo *algo)
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{
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int ff_len;
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int ret;
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/* first byte must be 0x00 */
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ret = *msg++;
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/* second byte must be 0x01 */
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ret |= *msg++ ^ 0x01;
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/* next ff_len bytes must be 0xff */
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ff_len = pad_len - algo->der_len - 3;
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ret |= *msg ^ 0xff;
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ret |= memcmp(msg, msg+1, ff_len-1);
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msg += ff_len;
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/* next byte must be 0x00 */
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ret |= *msg++;
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/* next der_len bytes must match der_prefix */
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ret |= memcmp(msg, algo->der_prefix, algo->der_len);
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return ret;
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}
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int padding_pkcs_15_verify(struct image_sign_info *info,
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uint8_t *msg, int msg_len,
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const uint8_t *hash, int hash_len)
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{
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struct checksum_algo *checksum = info->checksum;
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int ret, pad_len = msg_len - checksum->checksum_len;
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/* Check pkcs1.5 padding bytes. */
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ret = rsa_verify_padding(msg, pad_len, checksum);
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if (ret) {
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debug("In RSAVerify(): Padding check failed!\n");
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return -EINVAL;
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}
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/* Check hash. */
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if (memcmp((uint8_t *)msg + pad_len, hash, msg_len - pad_len)) {
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debug("In RSAVerify(): Hash check failed!\n");
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return -EACCES;
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}
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return 0;
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}
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#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
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static void u32_i2osp(uint32_t val, uint8_t *buf)
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{
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buf[0] = (uint8_t)((val >> 24) & 0xff);
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buf[1] = (uint8_t)((val >> 16) & 0xff);
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buf[2] = (uint8_t)((val >> 8) & 0xff);
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buf[3] = (uint8_t)((val >> 0) & 0xff);
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}
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/**
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* mask_generation_function1() - generate an octet string
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*
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* Generate an octet string used to check rsa signature.
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* It use an input octet string and a hash function.
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*
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* @checksum: A Hash function
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* @seed: Specifies an input variable octet string
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* @seed_len: Size of the input octet string
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* @output: Specifies the output octet string
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* @output_len: Size of the output octet string
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* @return 0 if the octet string was correctly generated, others on error
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*/
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static int mask_generation_function1(struct checksum_algo *checksum,
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uint8_t *seed, int seed_len,
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uint8_t *output, int output_len)
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{
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struct image_region region[2];
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int ret = 0, i, i_output = 0, region_count = 2;
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uint32_t counter = 0;
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uint8_t buf_counter[4], *tmp;
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int hash_len = checksum->checksum_len;
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memset(output, 0, output_len);
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region[0].data = seed;
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region[0].size = seed_len;
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region[1].data = &buf_counter[0];
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region[1].size = 4;
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tmp = malloc(hash_len);
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if (!tmp) {
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debug("%s: can't allocate array tmp\n", __func__);
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ret = -ENOMEM;
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goto out;
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}
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while (i_output < output_len) {
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u32_i2osp(counter, &buf_counter[0]);
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ret = checksum->calculate(checksum->name,
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region, region_count,
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tmp);
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if (ret < 0) {
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debug("%s: Error in checksum calculation\n", __func__);
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goto out;
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}
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i = 0;
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while ((i_output < output_len) && (i < hash_len)) {
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output[i_output] = tmp[i];
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i_output++;
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i++;
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}
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counter++;
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}
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out:
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free(tmp);
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return ret;
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}
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static int compute_hash_prime(struct checksum_algo *checksum,
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uint8_t *pad, int pad_len,
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uint8_t *hash, int hash_len,
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uint8_t *salt, int salt_len,
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uint8_t *hprime)
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{
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struct image_region region[3];
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int ret, region_count = 3;
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region[0].data = pad;
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region[0].size = pad_len;
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region[1].data = hash;
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region[1].size = hash_len;
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region[2].data = salt;
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region[2].size = salt_len;
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ret = checksum->calculate(checksum->name, region, region_count, hprime);
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if (ret < 0) {
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debug("%s: Error in checksum calculation\n", __func__);
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goto out;
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}
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out:
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return ret;
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}
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/*
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* padding_pss_verify() - verify the pss padding of a signature
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*
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* Only works with a rsa_pss_saltlen:-2 (default value) right now
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* saltlen:-1 "set the salt length to the digest length" is currently
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* not supported.
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*
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* @info: Specifies key and FIT information
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* @msg: byte array of message, len equal to msg_len
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* @msg_len: Message length
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* @hash: Pointer to the expected hash
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* @hash_len: Length of the hash
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*/
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int padding_pss_verify(struct image_sign_info *info,
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uint8_t *msg, int msg_len,
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const uint8_t *hash, int hash_len)
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{
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uint8_t *masked_db = NULL;
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int masked_db_len = msg_len - hash_len - 1;
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uint8_t *h = NULL, *hprime = NULL;
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int h_len = hash_len;
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uint8_t *db_mask = NULL;
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int db_mask_len = masked_db_len;
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uint8_t *db = NULL, *salt = NULL;
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int db_len = masked_db_len, salt_len = msg_len - hash_len - 2;
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uint8_t pad_zero[8] = { 0 };
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int ret, i, leftmost_bits = 1;
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uint8_t leftmost_mask;
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struct checksum_algo *checksum = info->checksum;
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/* first, allocate everything */
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masked_db = malloc(masked_db_len);
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h = malloc(h_len);
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db_mask = malloc(db_mask_len);
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db = malloc(db_len);
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salt = malloc(salt_len);
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hprime = malloc(hash_len);
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if (!masked_db || !h || !db_mask || !db || !salt || !hprime) {
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printf("%s: can't allocate some buffer\n", __func__);
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ret = -ENOMEM;
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goto out;
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}
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/* step 4: check if the last byte is 0xbc */
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if (msg[msg_len - 1] != 0xbc) {
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printf("%s: invalid pss padding (0xbc is missing)\n", __func__);
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ret = -EINVAL;
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goto out;
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}
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/* step 5 */
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memcpy(masked_db, msg, masked_db_len);
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memcpy(h, msg + masked_db_len, h_len);
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/* step 6 */
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leftmost_mask = (0xff >> (8 - leftmost_bits)) << (8 - leftmost_bits);
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if (masked_db[0] & leftmost_mask) {
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printf("%s: invalid pss padding ", __func__);
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printf("(leftmost bit of maskedDB not zero)\n");
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ret = -EINVAL;
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goto out;
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}
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/* step 7 */
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mask_generation_function1(checksum, h, h_len, db_mask, db_mask_len);
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/* step 8 */
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for (i = 0; i < db_len; i++)
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db[i] = masked_db[i] ^ db_mask[i];
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/* step 9 */
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db[0] &= 0xff >> leftmost_bits;
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/* step 10 */
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if (db[0] != 0x01) {
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printf("%s: invalid pss padding ", __func__);
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printf("(leftmost byte of db isn't 0x01)\n");
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ret = EINVAL;
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goto out;
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}
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/* step 11 */
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memcpy(salt, &db[1], salt_len);
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/* step 12 & 13 */
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compute_hash_prime(checksum, pad_zero, 8,
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(uint8_t *)hash, hash_len,
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salt, salt_len, hprime);
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/* step 14 */
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ret = memcmp(h, hprime, hash_len);
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out:
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free(hprime);
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free(salt);
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free(db);
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free(db_mask);
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free(h);
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free(masked_db);
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return ret;
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}
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#endif
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#if CONFIG_IS_ENABLED(FIT_SIGNATURE) || CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY)
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/**
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* rsa_verify_key() - Verify a signature against some data using RSA Key
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*
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* Verify a RSA PKCS1.5 signature against an expected hash using
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* the RSA Key properties in prop structure.
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*
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* @info: Specifies key and FIT information
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* @prop: Specifies key
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* @sig: Signature
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* @sig_len: Number of bytes in signature
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* @hash: Pointer to the expected hash
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* @key_len: Number of bytes in rsa key
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* @return 0 if verified, -ve on error
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*/
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static int rsa_verify_key(struct image_sign_info *info,
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struct key_prop *prop, const uint8_t *sig,
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const uint32_t sig_len, const uint8_t *hash,
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const uint32_t key_len)
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{
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int ret;
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#if !defined(USE_HOSTCC)
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struct udevice *mod_exp_dev;
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#endif
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struct checksum_algo *checksum = info->checksum;
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struct padding_algo *padding = info->padding;
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int hash_len;
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if (!prop || !sig || !hash || !checksum)
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return -EIO;
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if (sig_len != (prop->num_bits / 8)) {
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debug("Signature is of incorrect length %d\n", sig_len);
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return -EINVAL;
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}
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debug("Checksum algorithm: %s", checksum->name);
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/* Sanity check for stack size */
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if (sig_len > RSA_MAX_SIG_BITS / 8) {
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debug("Signature length %u exceeds maximum %d\n", sig_len,
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RSA_MAX_SIG_BITS / 8);
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return -EINVAL;
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}
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uint8_t buf[sig_len];
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hash_len = checksum->checksum_len;
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#if !defined(USE_HOSTCC)
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ret = uclass_get_device(UCLASS_MOD_EXP, 0, &mod_exp_dev);
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if (ret) {
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printf("RSA: Can't find Modular Exp implementation\n");
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return -EINVAL;
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}
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ret = rsa_mod_exp(mod_exp_dev, sig, sig_len, prop, buf);
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#else
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ret = rsa_mod_exp_sw(sig, sig_len, prop, buf);
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#endif
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if (ret) {
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debug("Error in Modular exponentation\n");
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return ret;
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}
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ret = padding->verify(info, buf, key_len, hash, hash_len);
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if (ret) {
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debug("In RSAVerify(): padding check failed!\n");
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return ret;
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}
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return 0;
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}
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#endif
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#if CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY)
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/**
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* rsa_verify_with_pkey() - Verify a signature against some data using
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* only modulus and exponent as RSA key properties.
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* @info: Specifies key information
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* @hash: Pointer to the expected hash
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* @sig: Signature
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* @sig_len: Number of bytes in signature
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*
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* Parse a RSA public key blob in DER format pointed to in @info and fill
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* a key_prop structure with properties of the key. Then verify a RSA PKCS1.5
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* signature against an expected hash using the calculated properties.
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*
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* Return 0 if verified, -ve on error
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*/
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int rsa_verify_with_pkey(struct image_sign_info *info,
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const void *hash, uint8_t *sig, uint sig_len)
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{
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struct key_prop *prop;
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int ret;
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/* Public key is self-described to fill key_prop */
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ret = rsa_gen_key_prop(info->key, info->keylen, &prop);
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if (ret) {
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debug("Generating necessary parameter for decoding failed\n");
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return ret;
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}
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ret = rsa_verify_key(info, prop, sig, sig_len, hash,
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info->crypto->key_len);
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rsa_free_key_prop(prop);
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return ret;
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}
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#else
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int rsa_verify_with_pkey(struct image_sign_info *info,
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const void *hash, uint8_t *sig, uint sig_len)
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{
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return -EACCES;
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}
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#endif
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#if CONFIG_IS_ENABLED(FIT_SIGNATURE)
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/**
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* rsa_verify_with_keynode() - Verify a signature against some data using
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* information in node with prperties of RSA Key like modulus, exponent etc.
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*
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* Parse sign-node and fill a key_prop structure with properties of the
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* key. Verify a RSA PKCS1.5 signature against an expected hash using
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* the properties parsed
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*
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* @info: Specifies key and FIT information
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* @hash: Pointer to the expected hash
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* @sig: Signature
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* @sig_len: Number of bytes in signature
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* @node: Node having the RSA Key properties
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* @return 0 if verified, -ve on error
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*/
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static int rsa_verify_with_keynode(struct image_sign_info *info,
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const void *hash, uint8_t *sig,
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uint sig_len, int node)
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{
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const void *blob = info->fdt_blob;
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struct key_prop prop;
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int length;
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int ret = 0;
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if (node < 0) {
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debug("%s: Skipping invalid node", __func__);
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return -EBADF;
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}
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prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
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prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
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prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
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if (!prop.public_exponent || length < sizeof(uint64_t))
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prop.public_exponent = NULL;
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prop.exp_len = sizeof(uint64_t);
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prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
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prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
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if (!prop.num_bits || !prop.modulus || !prop.rr) {
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debug("%s: Missing RSA key info", __func__);
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return -EFAULT;
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}
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ret = rsa_verify_key(info, &prop, sig, sig_len, hash,
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info->crypto->key_len);
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return ret;
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}
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#else
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static int rsa_verify_with_keynode(struct image_sign_info *info,
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const void *hash, uint8_t *sig,
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uint sig_len, int node)
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{
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return -EACCES;
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}
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#endif
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int rsa_verify_hash(struct image_sign_info *info,
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const uint8_t *hash, uint8_t *sig, uint sig_len)
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{
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int ret = -EACCES;
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if (CONFIG_IS_ENABLED(RSA_VERIFY_WITH_PKEY) && !info->fdt_blob) {
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/* don't rely on fdt properties */
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ret = rsa_verify_with_pkey(info, hash, sig, sig_len);
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return ret;
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}
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if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) {
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const void *blob = info->fdt_blob;
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int ndepth, noffset;
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int sig_node, node;
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char name[100];
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sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
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if (sig_node < 0) {
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debug("%s: No signature node found\n", __func__);
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return -ENOENT;
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}
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/* See if we must use a particular key */
|
|
if (info->required_keynode != -1) {
|
|
ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
|
|
info->required_keynode);
|
|
return ret;
|
|
}
|
|
|
|
/* Look for a key that matches our hint */
|
|
snprintf(name, sizeof(name), "key-%s", info->keyname);
|
|
node = fdt_subnode_offset(blob, sig_node, name);
|
|
ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
|
|
if (!ret)
|
|
return ret;
|
|
|
|
/* No luck, so try each of the keys in turn */
|
|
for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node,
|
|
&ndepth);
|
|
(noffset >= 0) && (ndepth > 0);
|
|
noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
|
|
if (ndepth == 1 && noffset != node) {
|
|
ret = rsa_verify_with_keynode(info, hash,
|
|
sig, sig_len,
|
|
noffset);
|
|
if (!ret)
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
int rsa_verify(struct image_sign_info *info,
|
|
const struct image_region region[], int region_count,
|
|
uint8_t *sig, uint sig_len)
|
|
{
|
|
/* Reserve memory for maximum checksum-length */
|
|
uint8_t hash[info->crypto->key_len];
|
|
int ret = -EACCES;
|
|
|
|
/*
|
|
* Verify that the checksum-length does not exceed the
|
|
* rsa-signature-length
|
|
*/
|
|
if (info->checksum->checksum_len >
|
|
info->crypto->key_len) {
|
|
debug("%s: invlaid checksum-algorithm %s for %s\n",
|
|
__func__, info->checksum->name, info->crypto->name);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Calculate checksum with checksum-algorithm */
|
|
ret = info->checksum->calculate(info->checksum->name,
|
|
region, region_count, hash);
|
|
if (ret < 0) {
|
|
debug("%s: Error in checksum calculation\n", __func__);
|
|
return -EINVAL;
|
|
}
|
|
|
|
return rsa_verify_hash(info, hash, sig, sig_len);
|
|
}
|