IMA: Add test for selinux measurement

Message ID	20210222023805.12846-1-nramas@linux.microsoft.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-integrity-owner@kernel.org> From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> To: pvorel@suse.cz, zohar@linux.ibm.com, paul@paul-moore.com, stephen.smalley.work@gmail.com Cc: tusharsu@linux.microsoft.com, ltp@lists.linux.it, linux-integrity@vger.kernel.org, selinux@vger.kernel.org Subject: [PATCH] IMA: Add test for selinux measurement Date: Sun, 21 Feb 2021 18:38:05 -0800 Message-Id: <20210222023805.12846-1-nramas@linux.microsoft.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	IMA: Add test for selinux measurement \| expand IMA: Add test for selinux measurement

diff --git a/runtest/ima b/runtest/ima index 5f4b4a7a1..29caa034a 100644 --- a/runtest/ima +++ b/runtest/ima @@ -5,4 +5,5 @@ ima_tpm ima_tpm.sh ima_violations ima_violations.sh ima_keys ima_keys.sh ima_kexec ima_kexec.sh +ima_selinux ima_selinux.sh evm_overlay evm_overlay.sh diff --git a/testcases/kernel/security/integrity/ima/README.md b/testcases/kernel/security/integrity/ima/README.md index 68d046678..8f2249767 100644 --- a/testcases/kernel/security/integrity/ima/README.md +++ b/testcases/kernel/security/integrity/ima/README.md @@ -37,6 +37,25 @@ see example in `kexec.policy`. The test attempts to kexec the existing running kernel image. To kexec a different kernel image export `IMA_KEXEC_IMAGE=<pathname>`. +### IMA SELinux test + +To enable IMA to measure SELinux state and policy, `ima_selinux.sh` +requires a readable IMA policy, as well as a loaded measure policy with +`measure func=CRITICAL_DATA label=selinux`, +see example in `selinux.policy`. + +As well as what's required for the IMA tests, SELinux tests require reading +the IMA policy allowed in the kernel configuration: +``` +CONFIG_IMA_READ_POLICY=y +``` + +The following kernel configuration is also required. It enables compiling +the Linux Security Module (LSM) namely SELinux. +``` +CONFIG_SECURITY_SELINUX=y +``` + ## EVM tests `evm_overlay.sh` requires a builtin IMA appraise tcb policy (e.g. `ima_policy=appraise_tcb` diff --git a/testcases/kernel/security/integrity/ima/datafiles/Makefile b/testcases/kernel/security/integrity/ima/datafiles/Makefile index 47a470416..280175b17 100644 --- a/testcases/kernel/security/integrity/ima/datafiles/Makefile +++ b/testcases/kernel/security/integrity/ima/datafiles/Makefile @@ -26,6 +26,6 @@ top_srcdir ?= ../../../../../.. include $(top_srcdir)/include/mk/env_pre.mk -SUBDIRS := ima_kexec ima_keys ima_policy +SUBDIRS := ima_kexec ima_keys ima_policy ima_selinux include $(top_srcdir)/include/mk/generic_trunk_target.mk diff --git a/testcases/kernel/security/integrity/ima/datafiles/ima_selinux/Makefile b/testcases/kernel/security/integrity/ima/datafiles/ima_selinux/Makefile new file mode 100644 index 000000000..35088fdbc --- /dev/null +++ b/testcases/kernel/security/integrity/ima/datafiles/ima_selinux/Makefile @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (c) Linux Test Project, 2021 + +top_srcdir ?= ../../../../../../.. + +include $(top_srcdir)/include/mk/env_pre.mk + +INSTALL_DIR := testcases/data/ima_selinux +INSTALL_TARGETS := *.policy + +include $(top_srcdir)/include/mk/generic_leaf_target.mk diff --git a/testcases/kernel/security/integrity/ima/datafiles/ima_selinux/selinux.policy b/testcases/kernel/security/integrity/ima/datafiles/ima_selinux/selinux.policy new file mode 100644 index 000000000..7cbe9352d --- /dev/null +++ b/testcases/kernel/security/integrity/ima/datafiles/ima_selinux/selinux.policy @@ -0,0 +1 @@ +measure func=CRITICAL_DATA label=selinux diff --git a/testcases/kernel/security/integrity/ima/tests/ima_selinux.sh b/testcases/kernel/security/integrity/ima/tests/ima_selinux.sh new file mode 100755 index 000000000..e5060a5e3 --- /dev/null +++ b/testcases/kernel/security/integrity/ima/tests/ima_selinux.sh @@ -0,0 +1,180 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (c) 2021 Microsoft Corporation +# Author: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> +# +# Verify measurement of SELinux policy hash and state. + +TST_NEEDS_CMDS="awk cut grep tail" +TST_CNT=2 +TST_NEEDS_DEVICE=1 +TST_SETUP="setup" + +. ima_setup.sh + +FUNC_CRITICAL_DATA='func=CRITICAL_DATA' +REQUIRED_POLICY="^measure.*($FUNC_CRITICAL_DATA)" + +setup() +{ + SELINUX_DIR=$(tst_get_selinux_dir) + if [ -z "$SELINUX_DIR" ]; then + tst_brk TCONF "SELinux is not enabled" + return + fi + require_ima_policy_content "$REQUIRED_POLICY" '-E' > $TST_TMPDIR/policy.txt +} + +# Format of the measured SELinux state data. +# +# initialized=1;enforcing=0;checkreqprot=1; +# network_peer_controls=1;open_perms=1;extended_socket_class=1; +# always_check_network=0;cgroup_seclabel=1;nnp_nosuid_transition=1; +# genfs_seclabel_symlinks=0; +validate_policy_capabilities() +{ + local measured_cap measured_value expected_value + local result=1 + local inx=7 + + # Policy capabilities flags start from "network_peer_controls" + # in the measured SELinux state at offset 7 for 'awk' + while [ $inx -lt 20 ]; do + measured_cap=$(echo $1 | awk -F'[=;]' -v inx="$inx" '{print $inx}') + inx=$(( $inx + 1 )) + + measured_value=$(echo $1 | awk -F'[=;]' -v inx="$inx" '{print $inx}') + expected_value=$(cat "$SELINUX_DIR/policy_capabilities/$measured_cap") + if [ "$measured_value" != "$expected_value" ];then + tst_res TWARN "$measured_cap: expected: $expected_value, got: $digest" + result=0 + fi + + inx=$(( $inx + 1 )) + done + + return $result +} + +# Trigger measurement of SELinux constructs and verify that +# the measured SELinux policy hash matches the hash of the policy +# loaded in kernel memory for SELinux. +test1() +{ + local policy_digest expected_policy_digest algorithm + local data_source_name="selinux" + local pattern="data_sources=[^[:space:]]*$data_source_name" + local tmp_file="$TST_TMPDIR/selinux_policy_tmp_file.txt" + + tst_res TINFO "verifying SELinux policy hash measurement" + + # Trigger a measurement by changing SELinux state + tst_update_selinux_state + + # Verify SELinux policy hash is measured and then validate that + # the measured policy hash matches the hash of the policy currently + # in kernel memory for SELinux + line=$(grep -E "selinux-policy-hash" $ASCII_MEASUREMENTS | tail -1) + if [ -z "$line" ]; then + tst_res TFAIL "SELinux policy hash not measured" + return + fi + + algorithm=$(echo "$line" | cut -d' ' -f4 | cut -d':' -f1) + policy_digest=$(echo "$line" | cut -d' ' -f6) + + expected_policy_digest="$(compute_digest $algorithm $SELINUX_DIR/policy)" || \ + tst_brk TCONF "cannot compute digest for $algorithm" + + if [ "$policy_digest" != "$expected_policy_digest" ]; then + tst_res TFAIL "Digest mismatch: expected: $expected_policy_digest, got: $policy_digest" + return + fi + + tst_res TPASS "SELinux policy hash measured correctly" +} + +# Trigger measurement of SELinux constructs and verify that +# the measured SELinux state matches the current SELinux +# configuration. +test2() +{ + tst_check_cmds xxd || return + + local measured_data state_file="$TST_TMPDIR/selinux_state.txt" + local data_source_name="selinux" + local pattern="data_sources=[^[:space:]]*$data_source_name" + local tmp_file="$TST_TMPDIR/selinux_state_tmp_file.txt" + local digest expected_digest algorithm + local initialized_value + local enforced_value expected_enforced_value + local checkreqprot_value expected_checkreqprot_value + local result + + tst_res TINFO "verifying SELinux state measurement" + + # Trigger a measurement by changing SELinux state + tst_update_selinux_state + + # Verify SELinux state is measured and then validate the measured + # state matches that currently set for SELinux + line=$(grep -E "selinux-state" $ASCII_MEASUREMENTS | tail -1) + if [ -z "$line" ]; then + tst_res TFAIL "SELinux state not measured" + return + fi + + digest=$(echo "$line" | cut -d' ' -f4 | cut -d':' -f2) + algorithm=$(echo "$line" | cut -d' ' -f4 | cut -d':' -f1) + + echo "$line" | cut -d' ' -f6 | xxd -r -p > $state_file + + expected_digest="$(compute_digest $algorithm $state_file)" || \ + tst_brk TCONF "cannot compute digest for $algorithm" + + if [ "$digest" != "$expected_digest" ]; then + tst_res TFAIL "digest mismatch: expected: $expected_digest, got: $digest" + return + fi + + # SELinux state is measured as the following string + # initialized=1;enforcing=0;checkreqprot=1; + # Value of 0 indicates the state is ON, and 1 indicates OFF + # + # enforce and checkreqprot measurement can be verified by + # comparing the value of the file "enforce" and "checkreqprot" + # respectively in the SELinux directory. + # "initialized" is an internal state and should be set to 1 + # if enforce and checkreqprot are measured correctly. + measured_data=$(cat $state_file) + enforced_value=$(echo $measured_data | awk -F'[=;]' '{print $4}') + expected_enforced_value=$(cat $SELINUX_DIR/enforce) + if [ "$expected_enforced_value" != "$enforced_value" ];then + tst_res TFAIL "enforce: expected: $expected_enforced_value, got: $enforced_value" + return + fi + + checkreqprot_value=$(echo $measured_data | awk -F'[=;]' '{print $6}') + expected_checkreqprot_value=$(cat $SELINUX_DIR/checkreqprot) + if [ "$expected_checkreqprot_value" != "$checkreqprot_value" ];then + tst_res TFAIL "checkreqprot: expected: $expected_checkreqprot_value, got: $checkreqprot_value" + return + fi + + initialized_value=$(echo $measured_data | awk -F'[=;]' '{print $2}') + if [ "$initialized_value" != "1" ];then + tst_res TFAIL "initialized: expected 1, got: $initialized_value" + return + fi + + validate_policy_capabilities $measured_data + result=$? + if [ $result = 0 ]; then + tst_res TFAIL "policy capabilities did not match" + return + fi + + tst_res TPASS "SELinux state measured correctly" +} + +tst_run

IMA: Add test for selinux measurement

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