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.rey...@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.rey...@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'
*
--
2.17.1
