linux-kernel - [PATCH 08/24] Copy secure_boot flag in boot params across kexec reboot

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Message-ID: <149141226780.31282.16496246694992359013.stgit@warthog.procyon.org.uk>
Date:   Wed, 05 Apr 2017 18:11:07 +0100
From:   David Howells <dhowells@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     gnomes@...rguk.ukuu.org.uk, linux-efi@...r.kernel.org,
        matthew.garrett@...ula.com, gregkh@...uxfoundation.org,
        dhowells@...hat.com, linux-security-module@...r.kernel.org,
        keyrings@...r.kernel.org, Dave Young <dyoung@...hat.com>
Subject: [PATCH 08/24] 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 d0a814a9d96a..3551bcaa1eaf 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;