While the appended kernel module signature can be verified, when loading a kernel module via either the init_module or the finit_module syscall, verifying the IMA signature requires access to the file descriptor, which is only available via the finit_module syscall. As "modprobe" does not provide a flag allowing the syscall - init_module or finit_module - to be specified, this patch does not load a kernel module.
This test simply verifies that on secure boot enabled systems with "CONFIG_IMA_ARCH_POLICY" configured, that at least an appended kernel module signature or an IMA signature is required based on the Kconfig and the runtime IMA policy.
Signed-off-by: Mimi Zohar zohar@linux.ibm.com Reviewed-by: Petr Vorel pvorel@suse.cz --- tools/testing/selftests/ima/Makefile | 2 +- tools/testing/selftests/ima/test_kernel_module.sh | 93 +++++++++++++++++++++++ 2 files changed, 94 insertions(+), 1 deletion(-) create mode 100755 tools/testing/selftests/ima/test_kernel_module.sh
diff --git a/tools/testing/selftests/ima/Makefile b/tools/testing/selftests/ima/Makefile index 00270de0b637..e1c59c510e1b 100644 --- a/tools/testing/selftests/ima/Makefile +++ b/tools/testing/selftests/ima/Makefile @@ -4,7 +4,7 @@ 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 test_kexec_file_load.sh +TEST_PROGS := test_kexec_load.sh test_kexec_file_load.sh test_kernel_module.sh TEST_FILES := ima_common_lib.sh
include ../lib.mk diff --git a/tools/testing/selftests/ima/test_kernel_module.sh b/tools/testing/selftests/ima/test_kernel_module.sh new file mode 100755 index 000000000000..319c601b9697 --- /dev/null +++ b/tools/testing/selftests/ima/test_kernel_module.sh @@ -0,0 +1,93 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# +# On secure boot enabled systems with "CONFIG_IMA_ARCH_POLICY" configured, +# this test verifies that at least an appended kernel module signature or +# an IMA signature is required. It does not attempt to load a kernel module. + +TEST="KERNEL_MODULE" +. ./ima_common_lib.sh + +trap "{ rm -f $IKCONFIG ; }" EXIT + +# Some of the IMA builtin policies may require the kernel modules to +# be signed, but these policy rules may be replaced with a custom +# policy. Only CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS persists after +# loading a custom policy. Check if it is enabled, before reading the +# IMA runtime sysfs policy file. +# Return 1 for IMA signature required and 0 for not required. +is_ima_sig_required() +{ + local ret=0 + + kconfig_enabled "CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS=y" \ + "IMA kernel module signature required" + if [ $? -eq 1 ]; then + return 1 + fi + + # The architecture specific or a custom policy may require the + # kernel module to be signed. Policy rules are walked sequentially. + # As a result, a policy rule may be defined, but might not necessarily + # be used. This test assumes if a policy rule is specified, that is + # the intent. + if [ $ima_read_policy -eq 1 ]; then + check_ima_policy "appraise" "func=MODULE_CHECK" \ + "appraise_type=imasig" + ret=$? + [ $ret -eq 1 ] && log_info "IMA signature required"; + fi + return $ret +} + +# loading kernel modules requires root privileges +require_root_privileges + +# Are appended signatures required? +if [ -e /sys/module/module/parameters/sig_enforce ]; then + sig_enforce=$(cat /sys/module/module/parameters/sig_enforce) + if [ $sig_enforce = "Y" ]; then + log_pass "appended kernel module signature required" + fi +fi + +get_secureboot_mode +if [ $? -eq 0 ]; then + log_skip "secure boot not enabled" +fi + +# get the kernel config +get_kconfig + +# Determine which kernel config options are enabled +kconfig_enabled "CONFIG_IMA_ARCH_POLICY=y" \ + "architecture specific policy enabled" +arch_policy=$? + +kconfig_enabled "CONFIG_MODULE_SIG=y" \ + "appended kernel modules signature enabled" +appended_sig_enabled=$? + +kconfig_enabled "CONFIG_IMA_READ_POLICY=y" "reading IMA policy permitted" +ima_read_policy=$? + +is_ima_sig_required +ima_sig_required=$? + +if [ $arch_policy -eq 0 ]; then + log_skip "architecture specific policy not enabled" +fi + +if [ $appended_sig_enabled -eq 1 ]; then + log_fail "appended kernel module signature enabled, but not required" +fi + +if [ $ima_sig_required -eq 1 ]; then + log_pass "IMA kernel module signature required" +fi + +if [ $ima_read_policy -eq 1 ]; then + log_fail "IMA kernel module signature not required" +else + log_skip "reading IMA policy not permitted" +fi