linux-kernel - [PATCH 08/16] Copy secure_boot flag in boot params across kexec reboot

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Date:   Wed, 16 Nov 2016 21:48:14 +0000
From:   David Howells <dhowells@...hat.com>
To:     keyrings@...r.kernel.org
Cc:     matthew.garrett@...ula.com, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org, dhowells@...hat.com,
        linux-security-module@...r.kernel.org,
        Dave Young <dyoung@...hat.com>
Subject: [PATCH 08/16] Copy secure_boot flag in boot params across kexec
 reboot

From: Dave Young <dyoung@...hat.com>

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
kernel.

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@...hat.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 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 3407b148c240..b843a4e57a9b 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;