linux/tools/testing/selftests/bpf/ima_setup.sh

#!/bin/bash
# SPDX-License-Identifier: GPL-2.0

set -e
set -u

IMA_POLICY_FILE="/sys/kernel/security/ima/policy"
TEST_BINARY="/bin/true"

usage()
{
        echo "Usage: $0 <setup|cleanup|run> <existing_tmp_dir>"
        exit 1
}

setup()
{
        local tmp_dir="$1"
        local mount_img="${tmp_dir}/test.img"
        local mount_dir="${tmp_dir}/mnt"
        local copied_bin_path="${mount_dir}/$(basename ${TEST_BINARY})"
        mkdir -p ${mount_dir}

        dd if=/dev/zero of="${mount_img}" bs=1M count=10

        local loop_device="$(losetup --find --show ${mount_img})"

        mkfs.ext4 "${loop_device}"
        mount "${loop_device}" "${mount_dir}"

        cp "${TEST_BINARY}" "${mount_dir}"
        local mount_uuid="$(blkid -s UUID -o value ${loop_device})"
        echo "measure func=BPRM_CHECK fsuuid=${mount_uuid}" > ${IMA_POLICY_FILE}
}

cleanup() {
        local tmp_dir="$1"
        local mount_img="${tmp_dir}/test.img"
        local mount_dir="${tmp_dir}/mnt"

        local loop_devices=$(losetup -j ${mount_img} -O NAME --noheadings)
        for loop_dev in "${loop_devices}"; do
                losetup -d $loop_dev
        done

        umount ${mount_dir}
        rm -rf ${tmp_dir}
}

run()
{
        local tmp_dir="$1"
        local mount_dir="${tmp_dir}/mnt"
        local copied_bin_path="${mount_dir}/$(basename ${TEST_BINARY})"

        exec "${copied_bin_path}"
}

main()
{
        [[ $# -ne 2 ]] && usage

        local action="$1"
        local tmp_dir="$2"

        [[ ! -d "${tmp_dir}" ]] && echo "Directory ${tmp_dir} doesn't exist" && exit 1

        if [[ "${action}" == "setup" ]]; then
                setup "${tmp_dir}"
        elif [[ "${action}" == "cleanup" ]]; then
                cleanup "${tmp_dir}"
        elif [[ "${action}" == "run" ]]; then
                run "${tmp_dir}"
        else
                echo "Unknown action: ${action}"
                exit 1
        fi
}

main "$@"