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 --- boot/Kconfig | 55 ++++++ boot/Makefile | 1 + boot/image-pre-load.c | 416 ++++++++++++++++++++++++++++++++++++++++++ include/image.h | 14 ++ 4 files changed, 486 insertions(+) create mode 100644 boot/image-pre-load.c
diff --git a/boot/Kconfig b/boot/Kconfig index b83a4e8400..cb5f48dcf9 100644 --- a/boot/Kconfig +++ b/boot/Kconfig @@ -993,6 +993,61 @@ config AUTOBOOT_MENU_SHOW
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 bool "Enable boot arguments" help diff --git a/boot/Makefile b/boot/Makefile index 2938c3f145..59752c65ca 100644 --- a/boot/Makefile +++ b/boot/Makefile @@ -26,6 +26,7 @@ obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += image-fdt.o obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += fdt_region.o obj-$(CONFIG_$(SPL_TPL_)FIT) += image-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_)FIT_SIGNATURE) += image-fit-sig.o obj-$(CONFIG_$(SPL_TPL_)FIT_CIPHER) += image-cipher.o diff --git a/boot/image-pre-load.c b/boot/image-pre-load.c new file mode 100644 index 0000000000..78d89069a9 --- /dev/null +++ b/boot/image-pre-load.c @@ -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, ®, 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, ®, 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; +} diff --git a/include/image.h b/include/image.h index 97e5f2eb24..fbcf70f5e4 100644 --- a/include/image.h +++ b/include/image.h @@ -48,6 +48,7 @@ struct fdt_region; extern ulong image_load_addr; /* Default Load Address */ extern ulong image_save_addr; /* Default Save Address */ 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 */ #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);
+/** + * 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' *