[ima-evm-utils] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

Message ID	20230126163812.1870942-3-roberto.sassu@huaweicloud.com (mailing list archive)
State	New
Headers	show Return-Path: <linux-integrity-owner@vger.kernel.org> From: Roberto Sassu <roberto.sassu@huaweicloud.com> 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, Roberto Sassu <roberto.sassu@huawei.com> Subject: [PATCH ima-evm-utils] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks Date: Thu, 26 Jan 2023 17:38:12 +0100 Message-Id: <20230126163812.1870942-3-roberto.sassu@huaweicloud.com> In-Reply-To: <20230126163812.1870942-1-roberto.sassu@huaweicloud.com> References: <20230126163812.1870942-1-roberto.sassu@huaweicloud.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	[ima-evm-utils] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks \| expand [ima-evm-utils] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

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 = $(check_SCRIPTS) check_SCRIPTS += ima_hash.test sign_verify.test boot_aggregate.test \ - fsverity.test portable_signatures.test + fsverity.test portable_signatures.test mmap_check.test + +check_PROGRAMS := test_mmap .PHONY: check_logs check_logs: diff --git a/tests/mmap_check.test b/tests/mmap_check.test new file mode 100755 index 000000000000..2efdd8e01785 --- /dev/null +++ b/tests/mmap_check.test @@ -0,0 +1,282 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Copyright (C) 2022-2023 Roberto Sassu <roberto.sassu@huawei.com> +# +# Check the behavior of MMAP_CHECK and MMAP_CHECK_REQPROT + +trap '_report_exit_and_cleanup _cleanup_env cleanup' SIGINT SIGTERM SIGSEGV EXIT + +# Base VERBOSE on the environment variable, if set. +VERBOSE="${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=$MMAP_CHECK_REQPROT_FOWNER" + +check_load_ima_rule() { + local rule_loaded + local result + local new_policy + + rule_loaded=$(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 "$FAIL" + fi + fi + + return "$OK" +} + +check_mmap() { + local hook="$1" + local arg="$2" + local test_file + local fowner + local rule + local result + local test_file_entry + + if ! test_file=$(mktemp -p "$PWD"); then + echo "${RED}Cannot write $test_file${NORM}" + return "$FAIL" + fi + + fowner="$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 "$FAIL" + fi + + check_load_ima_rule "$rule" + result=$? + if [ $result -ne "$OK" ]; then + return $result + fi + + test_mmap "$test_file" "$arg" + + if [ "$TFAIL" != "yes" ]; then + echo -n "Test (expect: found): " + else + echo -n "Test (expect: not found): " + fi + + echo -n "${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\") - " + + test_file_entry=$(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="$2" + local test_file + local fowner + local rule + local result + + if ! test_file=$(mktemp -p "$PWD"); then + echo "${RED}Cannot write $test_file${NORM}" + return "$FAIL" + fi + + echo "test" > "$test_file" + + if ! evmctl ima_sign -a sha256 --key "$key_path" "$test_file" &> /dev/null; then + echo "${RED}Cannot sign $test_file${NORM}" + return "$FAIL" + fi + + fowner="$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 "$FAIL" + fi + + check_load_ima_rule "$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 "$FAIL" + fi + + echo -n "Test (expect: denied): ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\") - " + if test_mmap "$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 check_mmap "MMAP_CHECK" "read_implies_exec" + +expect_fail check_mmap "MMAP_CHECK_REQPROT" "" +expect_pass check_mmap "MMAP_CHECK_REQPROT" "exec" +expect_fail check_mmap "MMAP_CHECK_REQPROT" "read_implies_exec" + +expect_pass check_deny "MMAP_CHECK" "mprotect" +expect_pass check_deny "MMAP_CHECK_REQPROT" "mprotect" + +expect_pass check_deny "MMAP_CHECK" "exec_on_writable" +expect_pass 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..c9396f66b3a9 --- /dev/null +++ b/tests/test_mmap.c @@ -0,0 +1,69 @@ +#include <stdio.h> +#include <errno.h> +#include <fcntl.h> +#include <string.h> +#include <unistd.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <sys/personality.h> + +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; +}

[ima-evm-utils] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

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