Messages in this thread | | | Date | Sun, 3 Feb 2019 23:02:58 +0100 | From | Petr Vorel <> | Subject | Re: [PATCH 3/3] selftests/ima: kexec_file_load syscall test |
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Hi Mimi,
> The kernel can be configured to verify PE signed kernel images, IMA > kernel image signatures, both types of signatures, or none. This test > verifies only properly signed kernel images are loaded into memory, > based on the kernel configuration and runtime policies.
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Petr Vorel <pvorel@suse.cz>
... > +++ b/tools/testing/selftests/ima/test_kexec_file_load.sh > @@ -0,0 +1,250 @@ > +#!/bin/sh > +# SPDX-License-Identifier: GPL-2.0+ # SPDX-License-Identifier: GPL-2.0-or-later > +# > +# Loading a kernel image via the kexec_file_load syscall can verify either > +# the IMA signature stored in the security.ima xattr or the PE signature, > +# both signatures depending on the IMA policy, or none. > +# > +# To determine whether the kernel image is signed, this test depends > +# on pesign and getfattr. This test also requires the kernel to be > +# built with CONFIG_IKCONFIG enabled and either CONFIG_IKCONFIG_PROC > +# enabled or access to the extract-ikconfig script. > + > +VERBOSE=1 Maybe allow to disable verbose without source change? VERBOSE="${VERBOSE:-1}"
> +EXTRACT_IKCONFIG=$(ls /lib/modules/`uname -r`/source/scripts/extract-ikconfig) > +IKCONFIG=/tmp/config-`uname -r` > +PROC_CONFIG="/proc/config.gz" > +KERNEL_IMAGE="/boot/vmlinuz-`uname -r`" > +PESIGN=/usr/bin/pesign > +GETFATTR=/usr/bin/getfattr > + > +TEST="$0" > +. ./common_lib.sh > + > +# Kselftest framework requirement - SKIP code is 4. > +ksft_skip=4 > + > +kconfig_enabled() > +{ > + RC=0 > + egrep -q $1 $IKCONFIG > + if [ $? -eq 0 ]; then > + RC=1 > + fi > + return $RC > +} This would be enough (grep with -e returns only 0 or 1): kconfig_enabled() { grep -E -q $1 $IKCONFIG } > + > +# policy rule format: action func=<keyword> [appraise_type=<type>] > +check_ima_policy() > +{ > + IMA_POLICY=/sys/kernel/security/ima/policy > + > + RC=0 > + if [ $# -eq 3 ]; then > + grep -e $2 $IMA_POLICY | grep -e "^$1.*$3" 2>&1 >/dev/null > + else > + grep -e $2 $IMA_POLICY | grep -e "^$1" 2>&1 >/dev/null > + fi > + if [ $? -eq 0 ]; then > + RC=1 > + fi > + return $RC > +} This would be enough and more descriptive: check_ima_policy() { local action="$1" local keyword="$2" local type="$3"
[ -n "$type" ] && type="appraise_type=$type" grep -q "^$action.*func=$keyword.*$type" /sys/kernel/security/ima/policy }
> + > +check_kconfig_options() > +{ > + # Attempt to get the kernel config first via proc, and then by > + # extracting it from the kernel image using scripts/extract-ikconfig. > + if [ ! -f $PROC_CONFIG ]; then > + modprobe configs 2>/dev/null > + fi > + if [ -f $PROC_CONFIG ]; then > + cat $PROC_CONFIG > $IKCONFIG > + fi > + > + if [ ! -f $IKCONFIG ]; then > + if [ ! -f $EXTRACT_IKCONFIG ]; then > + echo "$TEST: requires access to extract-ikconfig" >&2 > + exit $ksft_skip > + fi > + > + $EXTRACT_IKCONFIG $KERNEL_IMAGE > $IKCONFIG > + kconfig_enabled "CONFIG_IKCONFIG=y" > + if [ $? -eq 0 ]; then > + echo "$TEST: requires the kernel to be built with CONFIG_IKCONFIG" >&2 > + exit $ksft_skip > + fi > + fi > + > + kconfig_enabled "CONFIG_KEXEC_BZIMAGE_VERIFY_SIG=y" > + pe_sig_required=$? > + if [ $VERBOSE -ne 0 ] && [ $pe_sig_required -eq 1 ]; then > + echo "$TEST: [INFO] PE signed kernel image required" > + fi Checks for $VERBOSE here and in other kconfig_enabled usages bellow are a bit redundant. And you check for assigned variable now and then later on, you use these variables as global (and reset $ima_sig_required in check_runtime().
How about using functions instead: log_info() { echo "$TEST: [INFO] $1" } (Reducing some duplicity, IMHO helper functions in shell library used in all selftest tests would be useful)
kconfig_enabled() { local config="$1" local msg="$2" local ret
grep -E -q $config $IKCONFIG ret=$? [ $VERBOSE -ne 0 ] && [ $ret -eq 1 ] && log_info "$msg" return $ret }
ima_sig_enabled() { kconfig_enabled "CONFIG_KEXEC_BZIMAGE_VERIFY_SIG=y" \ "PE signed kernel image required" }
ima_sig_enabled() { kconfig_enabled "CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS=y" \ "IMA kernel image signature required" } Warning is printed each time, but that's deliberate. If it's not wanted, it can be moved into setup.
... > +check_kconfig_options > +check_for_apps > +check_runtime > +check_for_sigs > +kexec_file_load_test
> +rc=$? > +exit $rc These two are redundant.
Kind regards, Petr
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