linux-kernel - [PATCH 5.1 58/85] x86/ima: Check EFI_RUNTIME

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Date:   Fri,  7 Jun 2019 17:39:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Scott Wood <swood@...hat.com>,
        Mimi Zohar <zohar@...ux.ibm.com>
Subject: [PATCH 5.1 58/85] x86/ima: Check EFI_RUNTIME_SERVICES before using

From: Scott Wood <swood@...hat.com>

commit 558b523d46289f111d53d7c42211069063be5985 upstream.

Checking efi_enabled(EFI_BOOT) is not sufficient to ensure that
EFI runtime services are available, e.g. if efi=noruntime is used.

Without this, I get an oops on a PREEMPT_RT kernel where efi=noruntime is
the default.

Fixes: 399574c64eaf94e8 ("x86/ima: retry detecting secure boot mode")
Cc: stable@...r.kernel.org  (linux-5.0)
Signed-off-by: Scott Wood <swood@...hat.com>
Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kernel/ima_arch.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/x86/kernel/ima_arch.c
+++ b/arch/x86/kernel/ima_arch.c
@@ -17,6 +17,11 @@ static enum efi_secureboot_mode get_sb_m
 
 	size = sizeof(secboot);
 
+	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
+		pr_info("ima: secureboot mode unknown, no efi\n");
+		return efi_secureboot_mode_unknown;
+	}
+
 	/* Get variable contents into buffer */
 	status = efi.get_variable(efi_SecureBoot_name, &efi_variable_guid,
 				  NULL, &size, &secboot);