u-boot/lib/rsa/rsa-verify.c
Ruchika Gupta b37b46f042 rsa: Use checksum algorithms from struct hash_algo
Currently the hash functions used in RSA are called directly from the sha1
and sha256 libraries. Change the RSA checksum library to use the progressive
hash API's registered with struct hash_algo. This will allow the checksum
library to use the hardware accelerated progressive hash API's once available.

Signed-off-by: Ruchika Gupta <ruchika.gupta@freescale.com>
CC: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
(Fixed build error in am335x_boneblack_vboot due to duplicate CONFIG_DM)

Change-Id: Ic44279432f88d4e8594c6e94feb1cfcae2443a54
2015-01-29 17:09:59 -07:00

222 lines
5.7 KiB
C

/*
* Copyright (c) 2013, Google Inc.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef USE_HOSTCC
#include <common.h>
#include <fdtdec.h>
#include <asm/types.h>
#include <asm/byteorder.h>
#include <asm/errno.h>
#include <asm/types.h>
#include <asm/unaligned.h>
#include <dm.h>
#else
#include "fdt_host.h"
#include "mkimage.h"
#include <fdt_support.h>
#endif
#include <u-boot/rsa-mod-exp.h>
#include <u-boot/rsa.h>
/* Default public exponent for backward compatibility */
#define RSA_DEFAULT_PUBEXP 65537
/**
* rsa_verify_key() - Verify a signature against some data using RSA Key
*
* Verify a RSA PKCS1.5 signature against an expected hash using
* the RSA Key properties in prop structure.
*
* @prop: Specifies 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.
* @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 uint8_t *padding;
int pad_len;
int ret;
#if !defined(USE_HOSTCC)
struct udevice *mod_exp_dev;
#endif
if (!prop || !sig || !hash || !algo)
return -EIO;
if (sig_len != (prop->num_bits / 8)) {
debug("Signature is of incorrect length %d\n", sig_len);
return -EINVAL;
}
debug("Checksum algorithm: %s", algo->name);
/* Sanity check for stack size */
if (sig_len > RSA_MAX_SIG_BITS / 8) {
debug("Signature length %u exceeds maximum %d\n", sig_len,
RSA_MAX_SIG_BITS / 8);
return -EINVAL;
}
uint8_t buf[sig_len];
#if !defined(USE_HOSTCC)
ret = uclass_get_device(UCLASS_MOD_EXP, 0, &mod_exp_dev);
if (ret) {
printf("RSA: Can't find Modular Exp implementation\n");
return -EINVAL;
}
ret = rsa_mod_exp(mod_exp_dev, sig, sig_len, prop, buf);
#else
ret = rsa_mod_exp_sw(sig, sig_len, prop, buf);
#endif
if (ret) {
debug("Error in Modular exponentation\n");
return ret;
}
padding = algo->rsa_padding;
pad_len = algo->pad_len - algo->checksum_len;
/* Check pkcs1.5 padding bytes. */
if (memcmp(buf, padding, pad_len)) {
debug("In RSAVerify(): Padding check failed!\n");
return -EINVAL;
}
/* Check hash. */
if (memcmp((uint8_t *)buf + pad_len, hash, sig_len - pad_len)) {
debug("In RSAVerify(): Hash check failed!\n");
return -EACCES;
}
return 0;
}
/**
* rsa_verify_with_keynode() - Verify a signature against some data using
* information in node with prperties of RSA Key like modulus, exponent etc.
*
* Parse sign-node and fill a key_prop structure with properties of the
* key. Verify a RSA PKCS1.5 signature against an expected hash using
* the properties parsed
*
* @info: Specifies key and FIT information
* @hash: Pointer to the expected hash
* @sig: Signature
* @sig_len: Number of bytes in signature
* @node: Node having the RSA Key properties
* @return 0 if verified, -ve on error
*/
static int rsa_verify_with_keynode(struct image_sign_info *info,
const void *hash, uint8_t *sig,
uint sig_len, int node)
{
const void *blob = info->fdt_blob;
struct key_prop prop;
int length;
int ret = 0;
if (node < 0) {
debug("%s: Skipping invalid node", __func__);
return -EBADF;
}
prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
if (!prop.public_exponent || length < sizeof(uint64_t))
prop.public_exponent = NULL;
prop.exp_len = sizeof(uint64_t);
prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
if (!prop.num_bits || !prop.modulus) {
debug("%s: Missing RSA key info", __func__);
return -EFAULT;
}
ret = rsa_verify_key(&prop, sig, sig_len, hash, info->algo->checksum);
return ret;
}
int rsa_verify(struct image_sign_info *info,
const struct image_region region[], int region_count,
uint8_t *sig, uint sig_len)
{
const void *blob = info->fdt_blob;
/* Reserve memory for maximum checksum-length */
uint8_t hash[info->algo->checksum->pad_len];
int ndepth, noffset;
int sig_node, node;
char name[100];
int ret;
/*
* Verify that the checksum-length does not exceed the
* rsa-signature-length
*/
if (info->algo->checksum->checksum_len >
info->algo->checksum->pad_len) {
debug("%s: invlaid checksum-algorithm %s for %s\n",
__func__, info->algo->checksum->name, info->algo->name);
return -EINVAL;
}
sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
if (sig_node < 0) {
debug("%s: No signature node found\n", __func__);
return -ENOENT;
}
/* Calculate checksum with checksum-algorithm */
ret = info->algo->checksum->calculate(info->algo->checksum->name,
region, region_count, hash);
if (ret < 0) {
debug("%s: Error in checksum calculation\n", __func__);
return -EINVAL;
}
/* 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);
if (!ret)
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;
}