From patchwork Tue Jan 31 17:42:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13123213 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1EE4C636D4 for ; Tue, 31 Jan 2023 17:43:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231441AbjAaRn6 (ORCPT ); Tue, 31 Jan 2023 12:43:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231303AbjAaRnz (ORCPT ); Tue, 31 Jan 2023 12:43:55 -0500 Received: from frasgout13.his.huawei.com (frasgout13.his.huawei.com [14.137.139.46]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAAE920D14; Tue, 31 Jan 2023 09:43:38 -0800 (PST) Received: from mail02.huawei.com (unknown [172.18.147.229]) by frasgout13.his.huawei.com (SkyGuard) with ESMTP id 4P5sdc0Bf5z9xFg4; Wed, 1 Feb 2023 01:35:32 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP2 (Coremail) with SMTP id GxC2BwD3wVgpU9ljouLfAA--.11198S4; Tue, 31 Jan 2023 18:43:25 +0100 (CET) From: Roberto Sassu To: zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, jmorris@namei.org, serge@hallyn.com Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, stefanb@linux.ibm.com, viro@zeniv.linux.org.uk, pvorel@suse.cz, Roberto Sassu Subject: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks Date: Tue, 31 Jan 2023 18:42:45 +0100 Message-Id: <20230131174245.2343342-3-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230131174245.2343342-1-roberto.sassu@huaweicloud.com> References: <20230131174245.2343342-1-roberto.sassu@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: GxC2BwD3wVgpU9ljouLfAA--.11198S4 X-Coremail-Antispam: 1UD129KBjvAXoW3tw4kJFWDtF1kZFyDuF13XFb_yoW8JF4xGo WxKFWaq3Wftw43A3s5uFs7Ja4UG3Z7Ca15Arya9a15KF1kJryfC3WkAw1ftFW2kr4rurWv gF97Ww1rZrWDJw1fn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7v73VFW2AGmfu7bjvjm3 AaLaJ3UjIYCTnIWjp_UUUYX7kC6x804xWl14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK 8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr yl82xGYIkIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ew Av7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY 6r1j6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28IcxkI7V AKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCj r7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6x IIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAI w20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x 0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07jUfHUUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQAOBF1jj4hZ2AACsx X-CFilter-Loop: Reflected Precedence: bulk List-ID: From: Roberto Sassu Add tests to ensure that, after applying the kernel patch 'ima: Align ima_file_mmap() parameters with mmap_file LSM hook', the MMAP_CHECK hook checks the protections applied by the kernel and not those requested by the application. Also ensure that after applying 'ima: Introduce MMAP_CHECK_REQPROT hook', the MMAP_CHECK_REQPROT hook checks the protections requested by the application. Test both with the test_mmap application that by default requests the PROT_READ protection flag. Its syntax is: test_mmap where mode can be: - exec: adds the PROT_EXEC protection flag to mmap() - read_implies_exec: calls the personality() system call with READ_IMPLIES_EXEC as the first argument before mmap() - mprotect: adds the PROT_EXEC protection flag to a memory area in addition to PROT_READ - exec_on_writable: calls mmap() with PROT_EXEC on a file which has a writable mapping Check the different combinations of hooks/modes and ensure that a measurement entry is found in the IMA measurement list only when it is expected. No measurement entry should be found when only the PROT_READ protection flag is requested or the matching policy rule has the MMAP_CHECK_REQPROT hook and the personality() system call was called with READ_IMPLIES_EXEC. mprotect() with PROT_EXEC on an existing memory area protected with PROT_READ should be denied (with an appraisal rule), regardless of the MMAP hook specified in the policy. The same applies for mmap() with PROT_EXEC on a file with a writable mapping. Signed-off-by: Roberto Sassu Reviewed-by: Mimi Zohar --- Changelog v1: - Declare PATCHES and uses new expect_pass_if() and expect_fail_if() (suggested by Stefan) - Replace $FAIL with $HARDFAIL when the error occurs in the setup phase of the test (to not make an expect_fail test successful for other reasons than the focus of the test) - Declare local variables in one line (suggested by Stefan) - Print the test being executed at the beginning, so that the message always appears also if an error occurs - Print the result of the tests in a separate line and separate the output of each test tests/Makefile.am | 4 +- tests/mmap_check.test | 284 ++++++++++++++++++++++++++++++++++++++++++ tests/test_mmap.c | 75 +++++++++++ 3 files changed, 362 insertions(+), 1 deletion(-) create mode 100755 tests/mmap_check.test create mode 100644 tests/test_mmap.c diff --git a/tests/Makefile.am b/tests/Makefile.am index a0463b7b5b5d..ca9c4ca18380 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -2,7 +2,9 @@ check_SCRIPTS = TESTS = $(check_SCRIPTS) check_SCRIPTS += ima_hash.test sign_verify.test boot_aggregate.test \ - fsverity.test portable_signatures.test + fsverity.test portable_signatures.test mmap_check.test + +check_PROGRAMS := test_mmap .PHONY: check_logs check_logs: diff --git a/tests/mmap_check.test b/tests/mmap_check.test new file mode 100755 index 000000000000..a045ee867437 --- /dev/null +++ b/tests/mmap_check.test @@ -0,0 +1,284 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Copyright (C) 2022-2023 Roberto Sassu +# +# Check the behavior of MMAP_CHECK and MMAP_CHECK_REQPROT + +trap '_report_exit_and_cleanup _cleanup_env cleanup' SIGINT SIGTERM SIGSEGV EXIT + +PATCHES=( +'ima: Align ima_file_mmap() parameters with mmap_file LSM hook' +'ima: Introduce MMAP_CHECK_REQPROT hook' +) + +# Base VERBOSE on the environment variable, if set. +VERBOSE="${VERBOSE:-0}" + +cd "$(dirname "$0")" || exit "$FAIL" +export PATH=$PWD/../src:$PWD:$PATH +export LD_LIBRARY_PATH=$LD_LIBRARY_PATH +. ./functions.sh +_require evmctl + +cleanup() { + if [ "$g_loop_mounted" = "1" ]; then + popd > /dev/null || exit "$FAIL" + umount "$g_mountpoint" + fi + + if [ -n "$g_dev" ]; then + losetup -d "$g_dev" + fi + + if [ -n "$g_image" ]; then + rm -f "$g_image" + fi + + if [ -n "$g_mountpoint" ]; then + rm -Rf "$g_mountpoint" + fi + + if [ -n "$key_path_der" ]; then + rm -f "$key_path_der" + fi +} + +# Use the fsuuid= IMA policy keyword to select only files created/used by the +# tests below. Also use fowner= to differentiate between files created/used by +# individual tests. +IMA_UUID="28b23254-9467-44c0-b6ba-34b12e85a26e" +MMAP_CHECK_FOWNER=2000 +MMAP_CHECK_REQPROT_FOWNER=2001 +MEASURE_MMAP_CHECK_RULE="measure func=MMAP_CHECK fsuuid=$IMA_UUID fowner=$MMAP_CHECK_FOWNER" +MEASURE_MMAP_CHECK_REQPROT_RULE="measure func=MMAP_CHECK_REQPROT fsuuid=$IMA_UUID fowner=$MMAP_CHECK_REQPROT_FOWNER" +APPRAISE_MMAP_CHECK_RULE="appraise func=MMAP_CHECK fsuuid=$IMA_UUID fowner=$MMAP_CHECK_FOWNER" +APPRAISE_MMAP_CHECK_REQPROT_RULE="appraise func=MMAP_CHECK_REQPROT fsuuid=$IMA_UUID fowner=$MMAP_CHECK_REQPROT_FOWNER" + +check_load_ima_rule() { + local rule_loaded result new_policy + + rule_loaded=$(grep "$1" /sys/kernel/security/ima/policy) + if [ -z "$rule_loaded" ]; then + new_policy=$(mktemp -p "$g_mountpoint") + echo "$1" > "$new_policy" + echo "$new_policy" > /sys/kernel/security/ima/policy + result=$? + rm -f "$new_policy" + + if [ "$result" -ne 0 ]; then + echo "${RED}Failed to set IMA policy${NORM}" + return "$HARDFAIL" + fi + fi + + return "$OK" +} + +check_mmap() { + local hook="$1" + local arg="$2" + local test_file fowner rule result test_file_entry + + echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")" + + if ! test_file=$(mktemp -p "$PWD"); then + echo "${RED}Cannot write $test_file${NORM}" + return "$HARDFAIL" + fi + + fowner="$MMAP_CHECK_FOWNER" + rule="$MEASURE_MMAP_CHECK_RULE" + + if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then + fowner="$MMAP_CHECK_REQPROT_FOWNER" + rule="$MEASURE_MMAP_CHECK_REQPROT_RULE" + fi + + if ! chown "$fowner" "$test_file"; then + echo "${RED}Cannot change owner of $test_file${NORM}" + return "$HARDFAIL" + fi + + check_load_ima_rule "$rule" + result=$? + if [ $result -ne "$OK" ]; then + return $result + fi + + test_mmap "$test_file" "$arg" + + if [ "$TFAIL" != "yes" ]; then + echo -n "Result (expect found): " + else + echo -n "Result (expect not found): " + fi + + test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements) + if [ -z "$test_file_entry" ]; then + echo "not found" + return "$FAIL" + fi + + echo "found" + return "$OK" +} + +check_deny() { + local hook="$1" + local arg="$2" + local test_file fowner rule result + + echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")" + + if ! test_file=$(mktemp -p "$PWD"); then + echo "${RED}Cannot write $test_file${NORM}" + return "$HARDFAIL" + fi + + echo "test" > "$test_file" + + if ! evmctl ima_sign -a sha256 --key "$key_path" "$test_file" &> /dev/null; then + echo "${RED}Cannot sign $test_file${NORM}" + return "$HARDFAIL" + fi + + fowner="$MMAP_CHECK_FOWNER" + rule="$APPRAISE_MMAP_CHECK_RULE" + + if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then + fowner="$MMAP_CHECK_REQPROT_FOWNER" + rule="$APPRAISE_MMAP_CHECK_REQPROT_RULE" + fi + + if ! chown "$fowner" "$test_file"; then + echo "${RED}Cannot change owner of $test_file${NORM}" + return "$HARDFAIL" + fi + + check_load_ima_rule "$rule" + result=$? + if [ $result -ne "$OK" ]; then + return $result + fi + + if ! test_mmap "$test_file" exec > /dev/null; then + echo "${RED}Cannot read $test_file${NORM}" + return "$HARDFAIL" + fi + + if [ "$TFAIL" != "yes" ]; then + echo -n "Result (expect denied): " + else + echo -n "Result (expect allowed): " + fi + + if test_mmap "$test_file" "$arg"; then + echo "allowed" + return "$FAIL" + fi + + echo "denied" + return "$OK" +} + +# Run in the new environment if TST_ENV is set. +_run_env "$TST_KERNEL" "$PWD/$(basename "$0")" "TST_ENV=$TST_ENV TST_KERNEL=$TST_KERNEL PATH=$PATH LD_LIBRARY_PATH=$LD_LIBRARY_PATH VERBOSE=$VERBOSE" + +# Exit from the creator of the new environment. +_exit_env "$TST_KERNEL" + +# Mount filesystems in the new environment. +_init_env + +if [ "$(whoami)" != "root" ]; then + echo "${CYAN}This script must be executed as root${NORM}" + exit "$SKIP" +fi + +if [ ! -f /sys/kernel/security/ima/policy ]; then + echo "${CYAN}IMA policy file not found${NORM}" + exit "$SKIP" +fi + +if ! cat /sys/kernel/security/ima/policy &> /dev/null; then + echo "${CYAN}IMA policy file is not readable${NORM}" + exit "$SKIP" +fi + +if [ -n "$TST_KEY_PATH" ]; then + if [ "${TST_KEY_PATH:0:1}" != "/" ]; then + echo "${RED}Absolute path required for the signing key${NORM}" + exit "$FAIL" + fi + + if [ ! -f "$TST_KEY_PATH" ]; then + echo "${RED}Kernel signing key not found in $TST_KEY_PATH${NORM}" + exit "$FAIL" + fi + + key_path="$TST_KEY_PATH" +elif [ -f "$PWD/../signing_key.pem" ]; then + key_path="$PWD/../signing_key.pem" +elif [ -f "/lib/modules/$(uname -r)/source/certs/signing_key.pem" ]; then + key_path="/lib/modules/$(uname -r)/source/certs/signing_key.pem" +elif [ -f "/lib/modules/$(uname -r)/build/certs/signing_key.pem" ]; then + key_path="/lib/modules/$(uname -r)/build/certs/signing_key.pem" +else + echo "${CYAN}Kernel signing key not found${NORM}" + exit "$SKIP" +fi + +key_path_der=$(mktemp) + +openssl x509 -in "$key_path" -out "$key_path_der" -outform der +if ! keyctl padd asymmetric pubkey %keyring:.ima < "$key_path_der" &> /dev/null; then + echo "${RED}Public key cannot be added to the IMA keyring${NORM}" + exit "$FAIL" +fi + +g_mountpoint=$(mktemp -d) +g_image=$(mktemp) + +if [ -z "$g_mountpoint" ]; then + echo "${RED}Mountpoint directory not created${NORM}" + exit "$FAIL" +fi + +if ! dd if=/dev/zero of="$g_image" bs=1M count=20 &> /dev/null; then + echo "${RED}Cannot create test image${NORM}" + exit "$FAIL" +fi + +g_dev=$(losetup -f "$g_image" --show) +if [ -z "$g_dev" ]; then + echo "${RED}Cannot create loop device${NORM}" + exit "$FAIL" +fi + +if ! mkfs.ext4 -U "$IMA_UUID" -b 4096 "$g_dev" &> /dev/null; then + echo "${RED}Cannot format $g_dev${NORM}" + exit "$FAIL" +fi + +if ! mount -o i_version "$g_dev" "$g_mountpoint"; then + echo "${RED}Cannot mount loop device${NORM}" + exit "$FAIL" +fi + +g_loop_mounted=1 +pushd "$g_mountpoint" > /dev/null || exit "$FAIL" + +expect_fail check_mmap "MMAP_CHECK" "" +expect_pass check_mmap "MMAP_CHECK" "exec" +expect_pass_if '0' check_mmap "MMAP_CHECK" "read_implies_exec" + +expect_fail_if '1' check_mmap "MMAP_CHECK_REQPROT" "" +expect_pass_if '1' check_mmap "MMAP_CHECK_REQPROT" "exec" +expect_fail_if '1' check_mmap "MMAP_CHECK_REQPROT" "read_implies_exec" + +expect_pass check_deny "MMAP_CHECK" "mprotect" +expect_pass_if '1' check_deny "MMAP_CHECK_REQPROT" "mprotect" + +expect_pass check_deny "MMAP_CHECK" "exec_on_writable" +expect_pass_if '1' check_deny "MMAP_CHECK_REQPROT" "exec_on_writable" diff --git a/tests/test_mmap.c b/tests/test_mmap.c new file mode 100644 index 000000000000..6d1beb3bb6a2 --- /dev/null +++ b/tests/test_mmap.c @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2023 Huawei Technologies Duesseldorf GmbH + * + * Tool to test IMA MMAP_CHECK and MMAP_CHECK_REQPROT hooks. + */ +#include +#include +#include +#include +#include +#include +#include +#include + +int main(int argc, char *argv[]) +{ + struct stat st; + void *ptr, *ptr_write = NULL; + int ret, fd, fd_write, prot = PROT_READ; + + if (!argv[1]) + return -ENOENT; + + if (argv[2] && !strcmp(argv[2], "read_implies_exec")) { + ret = personality(READ_IMPLIES_EXEC); + if (ret < 0) + return ret; + } + + if (stat(argv[1], &st) == -1) + return -errno; + + if (argv[2] && !strcmp(argv[2], "exec_on_writable")) { + fd_write = open(argv[1], O_RDWR); + if (fd_write == -1) + return -errno; + + ptr_write = mmap(0, st.st_size, PROT_WRITE, MAP_SHARED, + fd_write, 0); + close(fd_write); + + if (ptr_write == (void *)-1) + return -errno; + } + + fd = open(argv[1], O_RDONLY); + if (fd == -1) { + if (ptr_write) + munmap(ptr_write, st.st_size); + + return -errno; + } + + if (argv[2] && !strncmp(argv[2], "exec", 4)) + prot |= PROT_EXEC; + + ptr = mmap(0, st.st_size, prot, MAP_PRIVATE, fd, 0); + + close(fd); + + if (ptr_write) + munmap(ptr_write, st.st_size); + + if (ptr == (void *)-1) + return -errno; + + ret = 0; + + if (argv[2] && !strcmp(argv[2], "mprotect")) + ret = mprotect(ptr, st.st_size, PROT_EXEC); + + munmap(ptr, st.st_size); + return ret; +}