selftests/ima: kexec_load syscall test

The kernel CONFIG_KEXEC_VERIFY_SIG option is limited to verifying a
kernel image's signature, when loaded via the kexec_file_load syscall.
There is no method for verifying a kernel image's signature loaded
via the kexec_load syscall.

This test verifies loading the kernel image via the kexec_load syscall
fails when the kernel CONFIG_KEXEC_VERIFY_SIG option is enabled on
systems with secureboot enabled[1].

[1] Detecting secureboot enabled is architecture specific.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/tools/testing/selftests/ima/test_kexec_load.sh b/tools/testing/selftests/ima/test_kexec_load.sh
new file mode 100755
index 000000000000..1c10093fb526
--- /dev/null
+++ b/tools/testing/selftests/ima/test_kexec_load.sh
@@ -0,0 +1,54 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+# Loading a kernel image via the kexec_load syscall should fail
+# when the kerne is CONFIG_KEXEC_VERIFY_SIG enabled and the system
+# is booted in secureboot mode.
+
+TEST="$0"
+EFIVARFS="/sys/firmware/efi/efivars"
+rc=0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+# kexec requires root privileges
+if [ $UID != 0 ]; then
+	echo "$TEST: must be run as root" >&2
+	exit $ksft_skip
+fi
+
+# Make sure that efivars is mounted in the normal location
+if ! grep -q "^\S\+ $EFIVARFS efivarfs" /proc/mounts; then
+	echo "$TEST: efivars is not mounted on $EFIVARFS" >&2
+	exit $ksft_skip
+fi
+
+# Get secureboot mode
+file="$EFIVARFS/SecureBoot-*"
+if [ ! -e $file ]; then
+	echo "$TEST: unknown secureboot mode" >&2
+	exit $ksft_skip
+fi
+secureboot=`hexdump $file | awk '{print substr($4,length($4),1)}'`
+
+# kexec_load should fail in secure boot mode
+KERNEL_IMAGE="/boot/vmlinuz-`uname -r`"
+kexec -l $KERNEL_IMAGE &>> /dev/null
+if [ $? == 0 ]; then
+	kexec -u
+	if [ "$secureboot" == "1" ]; then
+		echo "$TEST: kexec_load succeeded [FAIL]"
+		rc=1
+	else
+		echo "$TEST: kexec_load succeeded [PASS]"
+	fi
+else
+	if [ "$secureboot" == "1" ]; then
+		echo "$TEST: kexec_load failed [PASS]"
+	else
+		echo "$TEST: kexec_load failed [FAIL]"
+		rc=1
+	fi
+fi
+
+exit $rc