[PATCH 06/27] Copy secure_boot flag in boot params across kexec reboot

From: Matthew Garrett
Date: Wed Mar 06 2019 - 18:59:45 EST

From: Dave Young <dyoung@xxxxxxxxxx>

Kexec reboot in case secure boot being enabled does not keep the secure
boot mode in new kernel, so later one can load unsigned kernel via legacy
kexec_load. In this state, the system is missing the protections provided
by secure boot.

Adding a patch to fix this by retain the secure_boot flag in original

secure_boot flag in boot_params is set in EFI stub, but kexec bypasses the
stub. Fixing this issue by copying secure_boot flag across kexec reboot.

Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: "Lee, Chun-Yi" <jlee@xxxxxxxx>
cc: kexec@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Matthew Garrett <matthewgarrett@xxxxxxxxxx>
arch/x86/kernel/kexec-bzimage64.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 278cd07228dd..d49554b948fd 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -179,6 +179,7 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
if (efi_enabled(EFI_OLD_MEMMAP))
return 0;

+ params->secure_boot = boot_params.secure_boot;
ei->efi_loader_signature = current_ei->efi_loader_signature;
ei->efi_systab = current_ei->efi_systab;
ei->efi_systab_hi = current_ei->efi_systab_hi;