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boot: image: add a stage pre-load

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Add a stage pre-load that could
check or modify an image.

For the moment, only a header with a signature is
supported. This header has the following format:
- magic : 4 bytes
- version : 4 bytes
- header size : 4 bytes
- image size : 4 bytes
- offset image signature : 4 bytes
- flags : 4 bytes
- reserved0 : 4 bytes
- reserved1 : 4 bytes
- sha256 of the image signature : 32 bytes
- signature of the first 64 bytes : n bytes
- image signature : n bytes
- padding : up to header size

The stage uses a node /image/pre-load/sig to
get some informations:
- algo-name (mandatory) : name of the algo used to sign
- padding-name : name of padding used to sign
- signature-size : size of the signature (in the header)
- mandatory : set to yes if this sig is mandatory
- public-key (madatory) : value of the public key

Before running the image, the stage pre-load checks
the signature provided in the header.

This is an initial support, later we could add the
support of:
- ciphering
- uncompressing
- ...

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
This commit is contained in:
Philippe Reynes 2022-03-28 22:56:59 +02:00 committed by Tom Rini
parent f6bacf1d48
commit 982207435a
4 changed files with 486 additions and 0 deletions
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55
boot/Kconfig
View File

@ -1023,6 +1023,61 @@ config RESET_TO_RETRY
endmenu endmenu
menu "Image support"
config IMAGE_PRE_LOAD
bool "Image pre-load support"
help
Enable an image pre-load stage in the SPL.
This pre-load stage allows to do some manipulation
or check (for example signature check) on an image
before launching it.
config SPL_IMAGE_PRE_LOAD
bool "Image pre-load support within SPL"
depends on SPL && IMAGE_PRE_LOAD
help
Enable an image pre-load stage in the SPL.
This pre-load stage allows to do some manipulation
or check (for example signature check) on an image
before launching it.
config IMAGE_PRE_LOAD_SIG
bool "Image pre-load signature support"
depends on IMAGE_PRE_LOAD
select FIT_SIGNATURE
select RSA
select RSA_VERIFY_WITH_PKEY
help
Enable signature check support in the pre-load stage.
For this feature a very simple header is added before
the image with few fields:
- a magic
- the image size
- the signature
All other information (header size, type of signature,
...) are provided in the node /image/pre-load/sig of
u-boot.
config SPL_IMAGE_PRE_LOAD_SIG
bool "Image pre-load signature support witin SPL"
depends on SPL_IMAGE_PRE_LOAD && IMAGE_PRE_LOAD_SIG
select SPL_FIT_SIGNATURE
select SPL_RSA
select SPL_RSA_VERIFY_WITH_PKEY
help
Enable signature check support in the pre-load stage in the SPL.
For this feature a very simple header is added before
the image with few fields:
- a magic
- the image size
- the signature
All other information (header size, type of signature,
...) are provided in the node /image/pre-load/sig of
u-boot.
endmenu
config USE_BOOTARGS config USE_BOOTARGS
bool "Enable boot arguments" bool "Enable boot arguments"
help help

1
boot/Makefile
View File

@ -22,6 +22,7 @@ obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += image-fdt.o
obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += fdt_region.o obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += fdt_region.o
obj-$(CONFIG_$(SPL_TPL_)FIT) += image-fit.o obj-$(CONFIG_$(SPL_TPL_)FIT) += image-fit.o
obj-$(CONFIG_$(SPL_)MULTI_DTB_FIT) += boot_fit.o common_fit.o obj-$(CONFIG_$(SPL_)MULTI_DTB_FIT) += boot_fit.o common_fit.o
obj-$(CONFIG_$(SPL_TPL_)IMAGE_PRE_LOAD) += image-pre-load.o
obj-$(CONFIG_$(SPL_TPL_)IMAGE_SIGN_INFO) += image-sig.o obj-$(CONFIG_$(SPL_TPL_)IMAGE_SIGN_INFO) += image-sig.o
obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += image-fit-sig.o obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += image-fit-sig.o
obj-$(CONFIG_$(SPL_TPL_)FIT_CIPHER) += image-cipher.o obj-$(CONFIG_$(SPL_TPL_)FIT_CIPHER) += image-cipher.o

416
boot/image-pre-load.c Normal file
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@ -0,0 +1,416 @@
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2021 Philippe Reynes <philippe.reynes@softathome.com>
*/
#include <common.h>
#include <asm/global_data.h>
DECLARE_GLOBAL_DATA_PTR;
#include <image.h>
#include <mapmem.h>
#include <u-boot/sha256.h>
#define IMAGE_PRE_LOAD_SIG_MAGIC 0x55425348
#define IMAGE_PRE_LOAD_SIG_OFFSET_MAGIC 0
#define IMAGE_PRE_LOAD_SIG_OFFSET_IMG_LEN 4
#define IMAGE_PRE_LOAD_SIG_OFFSET_SIG 8
#define IMAGE_PRE_LOAD_PATH "/image/pre-load/sig"
#define IMAGE_PRE_LOAD_PROP_ALGO_NAME "algo-name"
#define IMAGE_PRE_LOAD_PROP_PADDING_NAME "padding-name"
#define IMAGE_PRE_LOAD_PROP_SIG_SIZE "signature-size"
#define IMAGE_PRE_LOAD_PROP_PUBLIC_KEY "public-key"
#define IMAGE_PRE_LOAD_PROP_MANDATORY "mandatory"
#ifndef CONFIG_SYS_BOOTM_LEN
/* use 8MByte as default max gunzip size */
#define CONFIG_SYS_BOOTM_LEN 0x800000
#endif
/*
* Information in the device-tree about the signature in the header
*/
struct image_sig_info {
char *algo_name; /* Name of the algo (eg: sha256,rsa2048) */
char *padding_name; /* Name of the padding */
u8 *key; /* Public signature key */
int key_len; /* Length of the public key */
u32 sig_size; /* size of the signature (in the header) */
int mandatory; /* Set if the signature is mandatory */
struct image_sign_info sig_info; /* Signature info */
};
/*
* Header of the signature header
*/
struct sig_header_s {
u32 magic;
u32 version;
u32 header_size;
u32 image_size;
u32 offset_img_sig;
u32 flags;
u32 reserved0;
u32 reserved1;
u8 sha256_img_sig[SHA256_SUM_LEN];
};
#define SIG_HEADER_LEN (sizeof(struct sig_header_s))
/*
* Offset of the image
*
* This value is used to skip the header before really launching the image
*/
ulong image_load_offset;
/*
* This function gathers information about the signature check
* that could be done before launching the image.
*
* return:
* < 0 => an error has occurred
* 0 => OK
* 1 => no setup
*/
static int image_pre_load_sig_setup(struct image_sig_info *info)
{
const void *algo_name, *padding_name, *key, *mandatory;
const u32 *sig_size;
int key_len;
int node, ret = 0;
if (!info) {
log_err("ERROR: info is NULL for image pre-load sig check\n");
ret = -EINVAL;
goto out;
}
memset(info, 0, sizeof(*info));
node = fdt_path_offset(gd_fdt_blob(), IMAGE_PRE_LOAD_PATH);
if (node < 0) {
log_info("INFO: no info for image pre-load sig check\n");
ret = 1;
goto out;
}
algo_name = fdt_getprop(gd_fdt_blob(), node,
IMAGE_PRE_LOAD_PROP_ALGO_NAME, NULL);
if (!algo_name) {
printf("ERROR: no algo_name for image pre-load sig check\n");
ret = -EINVAL;
goto out;
}
padding_name = fdt_getprop(gd_fdt_blob(), node,
IMAGE_PRE_LOAD_PROP_PADDING_NAME, NULL);
if (!padding_name) {
log_info("INFO: no padding_name provided, so using pkcs-1.5\n");
padding_name = "pkcs-1.5";
}
sig_size = fdt_getprop(gd_fdt_blob(), node,
IMAGE_PRE_LOAD_PROP_SIG_SIZE, NULL);
if (!sig_size) {
log_err("ERROR: no signature-size for image pre-load sig check\n");
ret = -EINVAL;
goto out;
}
key = fdt_getprop(gd_fdt_blob(), node,
IMAGE_PRE_LOAD_PROP_PUBLIC_KEY, &key_len);
if (!key) {
log_err("ERROR: no key for image pre-load sig check\n");
ret = -EINVAL;
goto out;
}
info->algo_name = (char *)algo_name;
info->padding_name = (char *)padding_name;
info->key = (uint8_t *)key;
info->key_len = key_len;
info->sig_size = fdt32_to_cpu(*sig_size);
mandatory = fdt_getprop(gd_fdt_blob(), node,
IMAGE_PRE_LOAD_PROP_MANDATORY, NULL);
if (mandatory && !strcmp((char *)mandatory, "yes"))
info->mandatory = 1;
/* Compute signature information */
info->sig_info.name = info->algo_name;
info->sig_info.padding = image_get_padding_algo(info->padding_name);
info->sig_info.checksum = image_get_checksum_algo(info->sig_info.name);
info->sig_info.crypto = image_get_crypto_algo(info->sig_info.name);
info->sig_info.key = info->key;
info->sig_info.keylen = info->key_len;
out:
return ret;
}
static int image_pre_load_sig_get_magic(ulong addr, u32 *magic)
{
struct sig_header_s *sig_header;
int ret = 0;
sig_header = (struct sig_header_s *)map_sysmem(addr, SIG_HEADER_LEN);
if (!sig_header) {
log_err("ERROR: can't map first header\n");
ret = -EFAULT;
goto out;
}
*magic = fdt32_to_cpu(sig_header->magic);
unmap_sysmem(sig_header);
out:
return ret;
}
static int image_pre_load_sig_get_header_size(ulong addr, u32 *header_size)
{
struct sig_header_s *sig_header;
int ret = 0;
sig_header = (struct sig_header_s *)map_sysmem(addr, SIG_HEADER_LEN);
if (!sig_header) {
log_err("ERROR: can't map first header\n");
ret = -EFAULT;
goto out;
}
*header_size = fdt32_to_cpu(sig_header->header_size);
unmap_sysmem(sig_header);
out:
return ret;
}
/*
* return:
* < 0 => no magic and magic mandatory (or error when reading magic)
* 0 => magic found
* 1 => magic NOT found
*/
static int image_pre_load_sig_check_magic(struct image_sig_info *info, ulong addr)
{
u32 magic;
int ret = 1;
ret = image_pre_load_sig_get_magic(addr, &magic);
if (ret < 0)
goto out;
if (magic != IMAGE_PRE_LOAD_SIG_MAGIC) {
if (info->mandatory) {
log_err("ERROR: signature is mandatory\n");
ret = -EINVAL;
goto out;
}
ret = 1;
goto out;
}
ret = 0; /* magic found */
out:
return ret;
}
static int image_pre_load_sig_check_header_sig(struct image_sig_info *info, ulong addr)
{
void *header;
struct image_region reg;
u32 sig_len;
u8 *sig;
int ret = 0;
/* Only map header of the header and its signature */
header = (void *)map_sysmem(addr, SIG_HEADER_LEN + info->sig_size);
if (!header) {
log_err("ERROR: can't map header\n");
ret = -EFAULT;
goto out;
}
reg.data = header;
reg.size = SIG_HEADER_LEN;
sig = (uint8_t *)header + SIG_HEADER_LEN;
sig_len = info->sig_size;
ret = info->sig_info.crypto->verify(&info->sig_info, &reg, 1, sig, sig_len);
if (ret) {
log_err("ERROR: header signature check has failed (err=%d)\n", ret);
ret = -EINVAL;
goto out_unmap;
}
out_unmap:
unmap_sysmem(header);
out:
return ret;
}
static int image_pre_load_sig_check_img_sig_sha256(struct image_sig_info *info, ulong addr)
{
struct sig_header_s *sig_header;
u32 header_size, offset_img_sig;
void *header;
u8 sha256_img_sig[SHA256_SUM_LEN];
int ret = 0;
sig_header = (struct sig_header_s *)map_sysmem(addr, SIG_HEADER_LEN);
if (!sig_header) {
log_err("ERROR: can't map first header\n");
ret = -EFAULT;
goto out;
}
header_size = fdt32_to_cpu(sig_header->header_size);
offset_img_sig = fdt32_to_cpu(sig_header->offset_img_sig);
header = (void *)map_sysmem(addr, header_size);
if (!header) {
log_err("ERROR: can't map header\n");
ret = -EFAULT;
goto out_sig_header;
}
sha256_csum_wd(header + offset_img_sig, info->sig_size,
sha256_img_sig, CHUNKSZ_SHA256);
ret = memcmp(sig_header->sha256_img_sig, sha256_img_sig, SHA256_SUM_LEN);
if (ret) {
log_err("ERROR: sha256 of image signature is invalid\n");
ret = -EFAULT;
goto out_header;
}
out_header:
unmap_sysmem(header);
out_sig_header:
unmap_sysmem(sig_header);
out:
return ret;
}
static int image_pre_load_sig_check_img_sig(struct image_sig_info *info, ulong addr)
{
struct sig_header_s *sig_header;
u32 header_size, image_size, offset_img_sig;
void *image;
struct image_region reg;
u32 sig_len;
u8 *sig;
int ret = 0;
sig_header = (struct sig_header_s *)map_sysmem(addr, SIG_HEADER_LEN);
if (!sig_header) {
log_err("ERROR: can't map first header\n");
ret = -EFAULT;
goto out;
}
header_size = fdt32_to_cpu(sig_header->header_size);
image_size = fdt32_to_cpu(sig_header->image_size);
offset_img_sig = fdt32_to_cpu(sig_header->offset_img_sig);
unmap_sysmem(sig_header);
image = (void *)map_sysmem(addr, header_size + image_size);
if (!image) {
log_err("ERROR: can't map full image\n");
ret = -EFAULT;
goto out;
}
reg.data = image + header_size;
reg.size = image_size;
sig = (uint8_t *)image + offset_img_sig;
sig_len = info->sig_size;
ret = info->sig_info.crypto->verify(&info->sig_info, &reg, 1, sig, sig_len);
if (ret) {
log_err("ERROR: signature check has failed (err=%d)\n", ret);
ret = -EINVAL;
goto out_unmap_image;
}
log_info("INFO: signature check has succeed\n");
out_unmap_image:
unmap_sysmem(image);
out:
return ret;
}
int image_pre_load_sig(ulong addr)
{
struct image_sig_info info;
int ret;
ret = image_pre_load_sig_setup(&info);
if (ret < 0)
goto out;
if (ret > 0) {
ret = 0;
goto out;
}
ret = image_pre_load_sig_check_magic(&info, addr);
if (ret < 0)
goto out;
if (ret > 0) {
ret = 0;
goto out;
}
/* Check the signature of the signature header */
ret = image_pre_load_sig_check_header_sig(&info, addr);
if (ret < 0)
goto out;
/* Check sha256 of the image signature */
ret = image_pre_load_sig_check_img_sig_sha256(&info, addr);
if (ret < 0)
goto out;
/* Check the image signature */
ret = image_pre_load_sig_check_img_sig(&info, addr);
if (!ret) {
u32 header_size;
ret = image_pre_load_sig_get_header_size(addr, &header_size);
if (ret) {
log_err("%s: can't get header size\n", __func__);
ret = -EINVAL;
goto out;
}
image_load_offset += header_size;
}
out:
return ret;
}
int image_pre_load(ulong addr)
{
int ret = 0;
image_load_offset = 0;
if (CONFIG_IS_ENABLED(IMAGE_PRE_LOAD_SIG))
ret = image_pre_load_sig(addr);
return ret;
}

14
include/image.h
View File

@ -48,6 +48,7 @@ struct fdt_region;
extern ulong image_load_addr; /* Default Load Address */ extern ulong image_load_addr; /* Default Load Address */
extern ulong image_save_addr; /* Default Save Address */ extern ulong image_save_addr; /* Default Save Address */
extern ulong image_save_size; /* Default Save Size */ extern ulong image_save_size; /* Default Save Size */
extern ulong image_load_offset; /* Default Load Address Offset */
/* An invalid size, meaning that the image size is not known */ /* An invalid size, meaning that the image size is not known */
#define IMAGE_SIZE_INVAL (-1UL) #define IMAGE_SIZE_INVAL (-1UL)
@ -1323,6 +1324,19 @@ struct crypto_algo *image_get_crypto_algo(const char *full_name);
*/ */
struct padding_algo *image_get_padding_algo(const char *name); struct padding_algo *image_get_padding_algo(const char *name);
/**
* image_pre_load() - Manage pre load header
*
* Manage the pre-load header before launching the image.
* It checks the signature of the image. It also set the
* variable image_load_offset to skip this header before
* launching the image.
*
* @param addr Address of the image
* @return: 0 on success, -ve on error
*/
int image_pre_load(ulong addr);
/** /**
* fit_image_verify_required_sigs() - Verify signatures marked as 'required' * fit_image_verify_required_sigs() - Verify signatures marked as 'required'
* *