Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity into next-integrity

From Mimi:

In Linux 4.19, a new LSM hook named security_kernel_load_data was
upstreamed, allowing LSMs and IMA to prevent the kexec_load
syscall.  Different signature verification methods exist for verifying
the kexec'ed kernel image.  This pull request adds additional support
in IMA to prevent loading unsigned kernel images via the kexec_load
syscall, independently of the IMA policy rules, based on the runtime
"secure boot" flag.  An initial IMA kselftest is included.

In addition, this pull request defines a new, separate keyring named
".platform" for storing the preboot/firmware keys needed for verifying
the kexec'ed kernel image's signature and includes the associated IMA
kexec usage of the ".platform" keyring.

(David Howell's and Josh Boyer's patches for reading the
preboot/firmware keys, which were previously posted for a different
use case scenario, are included here.)

4 files changed, 70 insertions, 0 deletions

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index f0017c831e57..10af879d7e1d 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -13,6 +13,7 @@ TARGETS += firmware
 TARGETS += ftrace
 TARGETS += futex
 TARGETS += gpio
+TARGETS += ima
 TARGETS += intel_pstate
 TARGETS += ipc
 TARGETS += kcmp
diff --git a/tools/testing/selftests/ima/Makefile b/tools/testing/selftests/ima/Makefile
new file mode 100644
index 000000000000..0b3adf5444b6
--- /dev/null
+++ b/tools/testing/selftests/ima/Makefile
@@ -0,0 +1,11 @@
+# Makefile for kexec_load
+
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
+
+ifeq ($(ARCH),x86)
+TEST_PROGS := test_kexec_load.sh
+
+include ../lib.mk
+
+endif
diff --git a/tools/testing/selftests/ima/config b/tools/testing/selftests/ima/config
new file mode 100644
index 000000000000..6bc86d4d9bb4
--- /dev/null
+++ b/tools/testing/selftests/ima/config
@@ -0,0 +1,4 @@
+CONFIG_IMA_APPRAISE
+CONFIG_IMA_ARCH_POLICY
+CONFIG_SECURITYFS
+CONFIG_KEXEC_VERIFY_SIG
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