u-boot/common/image-fit-sig.c
Thirupathaiah Annapureddy 182eeefcb4 vboot: add DTB policy for supporting multiple required conf keys
Currently FIT image must be signed by all required conf keys. This means
Verified Boot fails if there is a signature verification failure
using any required key in U-Boot DTB.

This patch introduces a new policy in DTB that can be set to any required
conf key. This means if verified boot passes with one of the required
keys, U-Boot will continue the OS hand off.

There were prior attempts to address this:
https://lists.denx.de/pipermail/u-boot/2019-April/366047.html
The above patch was failing "make tests".
https://lists.denx.de/pipermail/u-boot/2020-January/396629.html

Signed-off-by: Thirupathaiah Annapureddy <thiruan@linux.microsoft.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2020-10-12 21:30:37 -04:00

478 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2013, Google Inc.
*/
#ifdef USE_HOSTCC
#include "mkimage.h"
#include <time.h>
#else
#include <common.h>
#include <log.h>
#include <malloc.h>
DECLARE_GLOBAL_DATA_PTR;
#endif /* !USE_HOSTCC*/
#include <fdt_region.h>
#include <image.h>
#include <u-boot/rsa.h>
#include <u-boot/rsa-checksum.h>
#define IMAGE_MAX_HASHED_NODES 100
#ifdef USE_HOSTCC
void *host_blob;
void image_set_host_blob(void *blob)
{
host_blob = blob;
}
void *image_get_host_blob(void)
{
return host_blob;
}
#endif
/**
* fit_region_make_list() - Make a list of image regions
*
* Given a list of fdt_regions, create a list of image_regions. This is a
* simple conversion routine since the FDT and image code use different
* structures.
*
* @fit: FIT image
* @fdt_regions: Pointer to FDT regions
* @count: Number of FDT regions
* @region: Pointer to image regions, which must hold @count records. If
* region is NULL, then (except for an SPL build) the array will be
* allocated.
* @return: Pointer to image regions
*/
struct image_region *fit_region_make_list(const void *fit,
struct fdt_region *fdt_regions,
int count,
struct image_region *region)
{
int i;
debug("Hash regions:\n");
debug("%10s %10s\n", "Offset", "Size");
/*
* Use malloc() except in SPL (to save code size). In SPL the caller
* must allocate the array.
*/
#ifndef CONFIG_SPL_BUILD
if (!region)
region = calloc(sizeof(*region), count);
#endif
if (!region)
return NULL;
for (i = 0; i < count; i++) {
debug("%10x %10x\n", fdt_regions[i].offset,
fdt_regions[i].size);
region[i].data = fit + fdt_regions[i].offset;
region[i].size = fdt_regions[i].size;
}
return region;
}
static int fit_image_setup_verify(struct image_sign_info *info,
const void *fit, int noffset,
int required_keynode, char **err_msgp)
{
char *algo_name;
const char *padding_name;
if (fdt_totalsize(fit) > CONFIG_FIT_SIGNATURE_MAX_SIZE) {
*err_msgp = "Total size too large";
return 1;
}
if (fit_image_hash_get_algo(fit, noffset, &algo_name)) {
*err_msgp = "Can't get hash algo property";
return -1;
}
padding_name = fdt_getprop(fit, noffset, "padding", NULL);
if (!padding_name)
padding_name = RSA_DEFAULT_PADDING_NAME;
memset(info, '\0', sizeof(*info));
info->keyname = fdt_getprop(fit, noffset, FIT_KEY_HINT, NULL);
info->fit = (void *)fit;
info->node_offset = noffset;
info->name = algo_name;
info->checksum = image_get_checksum_algo(algo_name);
info->crypto = image_get_crypto_algo(algo_name);
info->padding = image_get_padding_algo(padding_name);
info->fdt_blob = gd_fdt_blob();
info->required_keynode = required_keynode;
printf("%s:%s", algo_name, info->keyname);
if (!info->checksum || !info->crypto || !info->padding) {
*err_msgp = "Unknown signature algorithm";
return -1;
}
return 0;
}
int fit_image_check_sig(const void *fit, int noffset, const void *data,
size_t size, int required_keynode, char **err_msgp)
{
struct image_sign_info info;
struct image_region region;
uint8_t *fit_value;
int fit_value_len;
*err_msgp = NULL;
if (fit_image_setup_verify(&info, fit, noffset, required_keynode,
err_msgp))
return -1;
if (fit_image_hash_get_value(fit, noffset, &fit_value,
&fit_value_len)) {
*err_msgp = "Can't get hash value property";
return -1;
}
region.data = data;
region.size = size;
if (info.crypto->verify(&info, &region, 1, fit_value, fit_value_len)) {
*err_msgp = "Verification failed";
return -1;
}
return 0;
}
static int fit_image_verify_sig(const void *fit, int image_noffset,
const char *data, size_t size,
const void *sig_blob, int sig_offset)
{
int noffset;
char *err_msg = "";
int verified = 0;
int ret;
/* Process all hash subnodes of the component image node */
fdt_for_each_subnode(noffset, fit, image_noffset) {
const char *name = fit_get_name(fit, noffset, NULL);
if (!strncmp(name, FIT_SIG_NODENAME,
strlen(FIT_SIG_NODENAME))) {
ret = fit_image_check_sig(fit, noffset, data,
size, -1, &err_msg);
if (ret) {
puts("- ");
} else {
puts("+ ");
verified = 1;
break;
}
}
}
if (noffset == -FDT_ERR_TRUNCATED || noffset == -FDT_ERR_BADSTRUCTURE) {
err_msg = "Corrupted or truncated tree";
goto error;
}
return verified ? 0 : -EPERM;
error:
printf(" error!\n%s for '%s' hash node in '%s' image node\n",
err_msg, fit_get_name(fit, noffset, NULL),
fit_get_name(fit, image_noffset, NULL));
return -1;
}
int fit_image_verify_required_sigs(const void *fit, int image_noffset,
const char *data, size_t size,
const void *sig_blob, int *no_sigsp)
{
int verify_count = 0;
int noffset;
int sig_node;
/* Work out what we need to verify */
*no_sigsp = 1;
sig_node = fdt_subnode_offset(sig_blob, 0, FIT_SIG_NODENAME);
if (sig_node < 0) {
debug("%s: No signature node found: %s\n", __func__,
fdt_strerror(sig_node));
return 0;
}
fdt_for_each_subnode(noffset, sig_blob, sig_node) {
const char *required;
int ret;
required = fdt_getprop(sig_blob, noffset, FIT_KEY_REQUIRED,
NULL);
if (!required || strcmp(required, "image"))
continue;
ret = fit_image_verify_sig(fit, image_noffset, data, size,
sig_blob, noffset);
if (ret) {
printf("Failed to verify required signature '%s'\n",
fit_get_name(sig_blob, noffset, NULL));
return ret;
}
verify_count++;
}
if (verify_count)
*no_sigsp = 0;
return 0;
}
/**
* fit_config_check_sig() - Check the signature of a config
*
* @fit: FIT to check
* @noffset: Offset of configuration node (e.g. /configurations/conf-1)
* @required_keynode: Offset in the control FDT of the required key node,
* if any. If this is given, then the configuration wil not
* pass verification unless that key is used. If this is
* -1 then any signature will do.
* @conf_noffset: Offset of the configuration subnode being checked (e.g.
* /configurations/conf-1/kernel)
* @err_msgp: In the event of an error, this will be pointed to a
* help error string to display to the user.
* @return 0 if all verified ok, <0 on error
*/
static int fit_config_check_sig(const void *fit, int noffset,
int required_keynode, int conf_noffset,
char **err_msgp)
{
char * const exc_prop[] = {"data", "data-size", "data-position"};
const char *prop, *end, *name;
struct image_sign_info info;
const uint32_t *strings;
const char *config_name;
uint8_t *fit_value;
int fit_value_len;
bool found_config;
int max_regions;
int i, prop_len;
char path[200];
int count;
config_name = fit_get_name(fit, conf_noffset, NULL);
debug("%s: fdt=%p, conf='%s', sig='%s'\n", __func__, gd_fdt_blob(),
fit_get_name(fit, noffset, NULL),
fit_get_name(gd_fdt_blob(), required_keynode, NULL));
*err_msgp = NULL;
if (fit_image_setup_verify(&info, fit, noffset, required_keynode,
err_msgp))
return -1;
if (fit_image_hash_get_value(fit, noffset, &fit_value,
&fit_value_len)) {
*err_msgp = "Can't get hash value property";
return -1;
}
/* Count the number of strings in the property */
prop = fdt_getprop(fit, noffset, "hashed-nodes", &prop_len);
end = prop ? prop + prop_len : prop;
for (name = prop, count = 0; name < end; name++)
if (!*name)
count++;
if (!count) {
*err_msgp = "Can't get hashed-nodes property";
return -1;
}
if (prop && prop_len > 0 && prop[prop_len - 1] != '\0') {
*err_msgp = "hashed-nodes property must be null-terminated";
return -1;
}
/* Add a sanity check here since we are using the stack */
if (count > IMAGE_MAX_HASHED_NODES) {
*err_msgp = "Number of hashed nodes exceeds maximum";
return -1;
}
/* Create a list of node names from those strings */
char *node_inc[count];
debug("Hash nodes (%d):\n", count);
found_config = false;
for (name = prop, i = 0; name < end; name += strlen(name) + 1, i++) {
debug(" '%s'\n", name);
node_inc[i] = (char *)name;
if (!strncmp(FIT_CONFS_PATH, name, strlen(FIT_CONFS_PATH)) &&
name[sizeof(FIT_CONFS_PATH) - 1] == '/' &&
!strcmp(name + sizeof(FIT_CONFS_PATH), config_name)) {
debug(" (found config node %s)", config_name);
found_config = true;
}
}
if (!found_config) {
*err_msgp = "Selected config not in hashed nodes";
return -1;
}
/*
* Each node can generate one region for each sub-node. Allow for
* 7 sub-nodes (hash-1, signature-1, etc.) and some extra.
*/
max_regions = 20 + count * 7;
struct fdt_region fdt_regions[max_regions];
/* Get a list of regions to hash */
count = fdt_find_regions(fit, node_inc, count,
exc_prop, ARRAY_SIZE(exc_prop),
fdt_regions, max_regions - 1,
path, sizeof(path), 0);
if (count < 0) {
*err_msgp = "Failed to hash configuration";
return -1;
}
if (count == 0) {
*err_msgp = "No data to hash";
return -1;
}
if (count >= max_regions - 1) {
*err_msgp = "Too many hash regions";
return -1;
}
/* Add the strings */
strings = fdt_getprop(fit, noffset, "hashed-strings", NULL);
if (strings) {
/*
* The strings region offset must be a static 0x0.
* This is set in tool/image-host.c
*/
fdt_regions[count].offset = fdt_off_dt_strings(fit);
fdt_regions[count].size = fdt32_to_cpu(strings[1]);
count++;
}
/* Allocate the region list on the stack */
struct image_region region[count];
fit_region_make_list(fit, fdt_regions, count, region);
if (info.crypto->verify(&info, region, count, fit_value,
fit_value_len)) {
*err_msgp = "Verification failed";
return -1;
}
return 0;
}
static int fit_config_verify_sig(const void *fit, int conf_noffset,
const void *sig_blob, int sig_offset)
{
int noffset;
char *err_msg = "";
int verified = 0;
int ret;
/* Process all hash subnodes of the component conf node */
fdt_for_each_subnode(noffset, fit, conf_noffset) {
const char *name = fit_get_name(fit, noffset, NULL);
if (!strncmp(name, FIT_SIG_NODENAME,
strlen(FIT_SIG_NODENAME))) {
ret = fit_config_check_sig(fit, noffset, sig_offset,
conf_noffset, &err_msg);
if (ret) {
puts("- ");
} else {
puts("+ ");
verified = 1;
break;
}
}
}
if (noffset == -FDT_ERR_TRUNCATED || noffset == -FDT_ERR_BADSTRUCTURE) {
err_msg = "Corrupted or truncated tree";
goto error;
}
if (verified)
return 0;
error:
printf(" error!\n%s for '%s' hash node in '%s' config node\n",
err_msg, fit_get_name(fit, noffset, NULL),
fit_get_name(fit, conf_noffset, NULL));
return -EPERM;
}
int fit_config_verify_required_sigs(const void *fit, int conf_noffset,
const void *sig_blob)
{
int noffset;
int sig_node;
int verified = 0;
int reqd_sigs = 0;
bool reqd_policy_all = true;
const char *reqd_mode;
/* Work out what we need to verify */
sig_node = fdt_subnode_offset(sig_blob, 0, FIT_SIG_NODENAME);
if (sig_node < 0) {
debug("%s: No signature node found: %s\n", __func__,
fdt_strerror(sig_node));
return 0;
}
/* Get required-mode policy property from DTB */
reqd_mode = fdt_getprop(sig_blob, sig_node, "required-mode", NULL);
if (reqd_mode && !strcmp(reqd_mode, "any"))
reqd_policy_all = false;
debug("%s: required-mode policy set to '%s'\n", __func__,
reqd_policy_all ? "all" : "any");
fdt_for_each_subnode(noffset, sig_blob, sig_node) {
const char *required;
int ret;
required = fdt_getprop(sig_blob, noffset, FIT_KEY_REQUIRED,
NULL);
if (!required || strcmp(required, "conf"))
continue;
reqd_sigs++;
ret = fit_config_verify_sig(fit, conf_noffset, sig_blob,
noffset);
if (ret) {
if (reqd_policy_all) {
printf("Failed to verify required signature '%s'\n",
fit_get_name(sig_blob, noffset, NULL));
return ret;
}
} else {
verified++;
if (!reqd_policy_all)
break;
}
}
if (reqd_sigs && !verified) {
printf("Failed to verify 'any' of the required signature(s)\n");
return -EPERM;
}
return 0;
}
int fit_config_verify(const void *fit, int conf_noffset)
{
return fit_config_verify_required_sigs(fit, conf_noffset,
gd_fdt_blob());
}