From: qianfan Zhao qianfanguijin@163.com
Not all Android tools use the id field for signing the image with sha1, so make this feature as optional and disabled default.
Signed-off-by: qianfan Zhao qianfanguijin@163.com --- common/Kconfig.boot | 14 +++++++++++ common/image-android.c | 55 +++++++++++++++++++++++++++++++++++++----- 2 files changed, 63 insertions(+), 6 deletions(-)
diff --git a/common/Kconfig.boot b/common/Kconfig.boot index a8d4be23a9..11fc8410a9 100644 --- a/common/Kconfig.boot +++ b/common/Kconfig.boot @@ -9,6 +9,20 @@ config ANDROID_BOOT_IMAGE This enables support for booting images which use the Android image format header.
+if ANDROID_BOOT_IMAGE + +config ANDROID_BOOT_IMAGE_VERIFY + bool "Enable signature verification" + select SHA1 + default n + help + This option enables signature verification of Android Boot Images, + using a hash signed and verified using SHA1. + Not all Android tools use the id field for signing the image with + sha1, if you are unsure about this, Say N here. + +endif # ANDROID_BOOT_IMAGE + config FIT bool "Support Flattened Image Tree" select HASH diff --git a/common/image-android.c b/common/image-android.c index 1fbbbba1eb..011ef756a7 100644 --- a/common/image-android.c +++ b/common/image-android.c @@ -44,11 +44,54 @@ static ulong android_image_get_kernel_addr(const struct andr_img_hdr *hdr) return hdr->kernel_addr; }
+#if CONFIG_IS_ENABLED(ANDROID_BOOT_IMAGE_VERIFY) +/* + * Not all Android tools use the id field for signing the image with + * sha1 (or anything) so we make this as an optional. + */ +static void android_image_update_sha1(sha1_context *ctx, const void *buf, + u32 size) +{ + if (size > 0) { + sha1_update(ctx, buf, size); + size = cpu_to_le32(size); + sha1_update(ctx, (unsigned char *)&size, sizeof(size)); + } +} + +static int android_image_verify_sha1(const struct andr_img_hdr *hdr) +{ + unsigned char output[SHA1_SUM_LEN]; + sha1_context ctx; + const void *p; + + sha1_starts(&ctx); + + p = (void *)hdr + hdr->page_size; /* kernel */ + android_image_update_sha1(&ctx, p, hdr->kernel_size); + + p += ALIGN(hdr->kernel_size, hdr->page_size); /* ramdisk */ + android_image_update_sha1(&ctx, p, hdr->ramdisk_size); + + p += ALIGN(hdr->ramdisk_size, hdr->page_size); /* second */ + android_image_update_sha1(&ctx, p, hdr->second_size); + + sha1_finish(&ctx, output); + + return memcmp(output, (unsigned char *)hdr->id, sizeof(output)); +} +#else +static int android_image_verify_sha1(const struct andr_img_hdr *hdr) +{ + return 0; +} +#endif + /** * android_image_get_kernel() - processes kernel part of Android boot images * @hdr: Pointer to image header, which is at the start * of the image. - * @verify: Checksum verification flag. Currently unimplemented. + * @verify: Checksum verification flag. * @os_data: Pointer to a ulong variable, will hold os data start * address. * @os_len: Pointer to a ulong variable, will hold os data length. @@ -66,11 +109,11 @@ int android_image_get_kernel(const struct andr_img_hdr *hdr, int verify, const struct image_header *ihdr = (const struct image_header *) ((uintptr_t)hdr + hdr->page_size);
- /* - * Not all Android tools use the id field for signing the image with - * sha1 (or anything) so we don't check it. It is not obvious that the - * string is null terminated so we take care of this. - */ + if (verify && android_image_verify_sha1(hdr)) { + puts("Bad Data Hash\n"); + return -EACCES; + } + strncpy(andr_tmp_str, hdr->name, ANDR_BOOT_NAME_SIZE); andr_tmp_str[ANDR_BOOT_NAME_SIZE] = '\0'; if (strlen(andr_tmp_str))