fc2f4246b4
Public exponentiation which is required in rsa verify functionality is tightly integrated with verification code in rsa_verify.c. The patch splits the file into twp separating the modular exponentiation. 1. rsa-verify.c - The file parses device tree keys node to fill a keyprop structure. The keyprop structure can then be converted to implementation specific format. (struct rsa_pub_key for sw implementation) - The parsed device tree node is then passed to a generic rsa_mod_exp function. 2. rsa-mod-exp.c Move the software specific functions related to modular exponentiation from rsa-verify.c to this file. Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com> CC: Simon Glass <sjg@chromium.org> Acked-by: Simon Glass <sjg@chromium.org>
204 lines
5.2 KiB
C
204 lines
5.2 KiB
C
/*
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* Copyright (c) 2013, Google Inc.
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*
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* SPDX-License-Identifier: GPL-2.0+
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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 <asm/types.h>
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#include <asm/byteorder.h>
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#include <asm/errno.h>
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#include <asm/types.h>
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#include <asm/unaligned.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 <u-boot/rsa-mod-exp.h>
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#include <u-boot/rsa.h>
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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_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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* @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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* @algo: Checksum algo structure having information on RSA padding etc.
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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 key_prop *prop, const uint8_t *sig,
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const uint32_t sig_len, const uint8_t *hash,
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struct checksum_algo *algo)
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{
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const uint8_t *padding;
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int pad_len;
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int ret;
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if (!prop || !sig || !hash || !algo)
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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", algo->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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ret = rsa_mod_exp_sw(sig, sig_len, prop, buf);
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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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padding = algo->rsa_padding;
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pad_len = algo->pad_len - algo->checksum_len;
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/* Check pkcs1.5 padding bytes. */
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if (memcmp(buf, padding, pad_len)) {
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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 *)buf + pad_len, hash, sig_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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/**
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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) {
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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(&prop, sig, sig_len, hash, info->algo->checksum);
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return ret;
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}
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int rsa_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 void *blob = info->fdt_blob;
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/* Reserve memory for maximum checksum-length */
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uint8_t hash[info->algo->checksum->pad_len];
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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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int ret;
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/*
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* Verify that the checksum-length does not exceed the
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* rsa-signature-length
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*/
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if (info->algo->checksum->checksum_len >
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info->algo->checksum->pad_len) {
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debug("%s: invlaid checksum-algorithm %s for %s\n",
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__func__, info->algo->checksum->name, info->algo->name);
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return -EINVAL;
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}
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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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/* Calculate checksum with checksum-algorithm */
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info->algo->checksum->calculate(region, region_count, hash);
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/* See if we must use a particular key */
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if (info->required_keynode != -1) {
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ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
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info->required_keynode);
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if (!ret)
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return ret;
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}
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/* Look for a key that matches our hint */
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snprintf(name, sizeof(name), "key-%s", info->keyname);
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node = fdt_subnode_offset(blob, sig_node, name);
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ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
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if (!ret)
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return ret;
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/* No luck, so try each of the keys in turn */
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for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node, &ndepth);
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(noffset >= 0) && (ndepth > 0);
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noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
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if (ndepth == 1 && noffset != node) {
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ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
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noffset);
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if (!ret)
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break;
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}
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}
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return ret;
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}
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