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authorIlias Apalodimas <ilias.apalodimas@linaro.org>2022-09-16 11:14:35 +0300
committerArd Biesheuvel <ardb@kernel.org>2022-09-27 14:26:16 +0300
commit71c7adc9fffd4e38ebc197314f6909c9fd6051ef (patch)
treeac1a759061e5b0b0ae90f5ad6dc15a31066b4f4a /drivers/firmware
parent566331696329c2f9ca0fe2a55a5dd029ac43d2d2 (diff)
downloadlinux-71c7adc9fffd4e38ebc197314f6909c9fd6051ef.tar.xz
efi/libstub: measure EFI LoadOptions
The EFI TCG spec, in §10.2.6 "Measuring UEFI Variables and UEFI GPT Data", only reasons about the load options passed to a loaded image in the context of boot options booted directly from the BDS, which are measured into PCR #5 along with the rest of the Boot#### EFI variable. However, the UEFI spec mentions the following in the documentation of the LoadImage() boot service and the EFI_LOADED_IMAGE protocol: The caller may fill in the image’s "load options" data, or add additional protocol support to the handle before passing control to the newly loaded image by calling EFI_BOOT_SERVICES.StartImage(). The typical boot sequence for Linux EFI systems is to load GRUB via a boot option from the BDS, which [hopefully] calls LoadImage to load the kernel image, passing the kernel command line via the mechanism described above. This means that we cannot rely on the firmware implementing TCG measured boot to ensure that the kernel command line gets measured before the image is started, so the EFI stub will have to take care of this itself. Given that PCR #5 has an official use in the TCG measured boot spec, let's avoid it in this case. Instead, add a measurement in PCR #9 (which we already use for our initrd) and extend it with the LoadOptions measurements Co-developed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/efi/libstub/efi-stub-helper.c10
-rw-r--r--drivers/firmware/efi/libstub/efistub.h1
2 files changed, 11 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index e0bb2025930b..b4c2267c9502 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -336,6 +336,7 @@ void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_si
enum efistub_event {
EFISTUB_EVT_INITRD,
+ EFISTUB_EVT_LOAD_OPTIONS,
EFISTUB_EVT_COUNT,
};
@@ -352,6 +353,11 @@ static const struct {
INITRD_EVENT_TAG_ID,
STR_WITH_SIZE("Linux initrd")
},
+ [EFISTUB_EVT_LOAD_OPTIONS] = {
+ 9,
+ LOAD_OPTIONS_EVENT_TAG_ID,
+ STR_WITH_SIZE("LOADED_IMAGE::LoadOptions")
+ },
};
static efi_status_t efi_measure_tagged_event(unsigned long load_addr,
@@ -423,6 +429,10 @@ char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len)
efi_status_t status;
u32 options_chars;
+ if (options_size > 0)
+ efi_measure_tagged_event((unsigned long)options, options_size,
+ EFISTUB_EVT_LOAD_OPTIONS);
+
efi_apply_loadoptions_quirk((const void **)&options, &options_size);
options_chars = options_size / sizeof(efi_char16_t);
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 9ed5889594ed..a30fb5d8ef05 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -753,6 +753,7 @@ union apple_properties_protocol {
typedef u32 efi_tcg2_event_log_format;
#define INITRD_EVENT_TAG_ID 0x8F3B22ECU
+#define LOAD_OPTIONS_EVENT_TAG_ID 0x8F3B22EDU
#define EV_EVENT_TAG 0x00000006U
#define EFI_TCG2_EVENT_HEADER_VERSION 0x1