|
 |
90dacf5 |
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
|
90dacf5 |
From: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
|
|
|
90dacf5 |
Date: Fri, 4 Mar 2022 09:31:43 +0100
|
|
|
90dacf5 |
Subject: [PATCH] grub-core/loader/efi/chainloader.c: do not validate
|
|
|
90dacf5 |
chainloader twice
|
|
|
90dacf5 |
|
|
|
90dacf5 |
On secureboot systems, with shimlock verifier, call to
|
|
|
90dacf5 |
grub_file_open(, GRUB_FILE_TYPE_EFI_CHAINLOADED_IMAGE) will already
|
|
|
90dacf5 |
pass the chainloader target through shim-lock protocol verify
|
|
|
90dacf5 |
call. And create a TPM measurement. If verification fails,
|
|
|
90dacf5 |
grub_cmd_chainloader will fail at file open time.
|
|
|
90dacf5 |
|
|
|
90dacf5 |
This makes previous code paths for negative, and zero return codes
|
|
|
90dacf5 |
from grub_linuxefi_secure_validate unreachable under secureboot. But
|
|
|
90dacf5 |
also breaking measurements compatibility with 2.04+linuxefi codebases,
|
|
|
90dacf5 |
as the chainloader file is passed through shim_lock->verify() twice
|
|
|
90dacf5 |
(via verifier & direct call to grub_linuxefi_secure_validate)
|
|
|
90dacf5 |
extending the PCRs twice.
|
|
|
90dacf5 |
|
|
|
90dacf5 |
This reduces grub_loader options to perform
|
|
|
90dacf5 |
grub_secureboot_chainloader when secureboot is on, and otherwise
|
|
|
90dacf5 |
attempt grub_chainloader_boot.
|
|
|
90dacf5 |
|
|
|
90dacf5 |
It means that booting with secureboot off, yet still with shim (which
|
|
|
90dacf5 |
always verifies things successfully), will stop choosing
|
|
|
90dacf5 |
grub_secureboot_chainloader, and opting for a more regular
|
|
|
90dacf5 |
loadimage/startimage codepath. If we want to use the
|
|
|
90dacf5 |
grub_secureboot_chainloader codepath in such scenarios we should adapt
|
|
|
90dacf5 |
the code to simply check for shim_lock protocol presence /
|
|
|
90dacf5 |
shim_lock->context() success?! But I am not sure if that is necessary.
|
|
|
90dacf5 |
|
|
|
90dacf5 |
This patch must not be ported to older editions of grub code bases
|
|
|
90dacf5 |
that do not have verifiers framework, or it is not builtin, or
|
|
|
90dacf5 |
shim-lock-verifier is an optional module.
|
|
|
90dacf5 |
|
|
|
90dacf5 |
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
|
|
|
90dacf5 |
---
|
|
|
90dacf5 |
grub-core/loader/efi/chainloader.c | 8 ++------
|
|
|
90dacf5 |
1 file changed, 2 insertions(+), 6 deletions(-)
|
|
|
90dacf5 |
|
|
|
90dacf5 |
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
|
|
|
e622855 |
index 3af6b12292..644cd2e56f 100644
|
|
|
90dacf5 |
--- a/grub-core/loader/efi/chainloader.c
|
|
|
90dacf5 |
+++ b/grub-core/loader/efi/chainloader.c
|
|
|
90dacf5 |
@@ -906,7 +906,6 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
|
|
90dacf5 |
grub_efi_device_path_t *dp = 0;
|
|
|
90dacf5 |
char *filename;
|
|
|
90dacf5 |
void *boot_image = 0;
|
|
|
90dacf5 |
- int rc;
|
|
|
90dacf5 |
|
|
|
90dacf5 |
if (argc == 0)
|
|
|
90dacf5 |
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
|
|
|
90dacf5 |
@@ -1082,9 +1081,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
|
|
90dacf5 |
orig_dev = 0;
|
|
|
90dacf5 |
}
|
|
|
90dacf5 |
|
|
|
90dacf5 |
- rc = grub_linuxefi_secure_validate((void *)(unsigned long)address, fsize);
|
|
|
90dacf5 |
- grub_dprintf ("chain", "linuxefi_secure_validate: %d\n", rc);
|
|
|
90dacf5 |
- if (rc > 0)
|
|
|
90dacf5 |
+ if (grub_efi_get_secureboot () == GRUB_EFI_SECUREBOOT_MODE_ENABLED)
|
|
|
90dacf5 |
{
|
|
|
90dacf5 |
grub_file_close (file);
|
|
|
90dacf5 |
grub_device_close (dev);
|
|
|
90dacf5 |
@@ -1092,7 +1089,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
|
|
90dacf5 |
grub_secureboot_chainloader_unload, 0);
|
|
|
90dacf5 |
return 0;
|
|
|
90dacf5 |
}
|
|
|
90dacf5 |
- else if (rc == 0)
|
|
|
90dacf5 |
+ else
|
|
|
90dacf5 |
{
|
|
|
90dacf5 |
grub_load_and_start_image(boot_image);
|
|
|
90dacf5 |
grub_file_close (file);
|
|
|
90dacf5 |
@@ -1101,7 +1098,6 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
|
|
|
90dacf5 |
|
|
|
90dacf5 |
return 0;
|
|
|
90dacf5 |
}
|
|
|
90dacf5 |
- // -1 fall-through to fail
|
|
|
90dacf5 |
|
|
|
90dacf5 |
fail:
|
|
|
90dacf5 |
if (orig_dev)
|