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[104.199.75.203]) by smtp.gmail.com with ESMTPSA id g131sm6353127wma.35.2020.11.24.07.12.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Nov 2020 07:12:14 -0800 (PST) From: KP Singh To: James Morris , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Florent Revest , Brendan Jackman , Mimi Zohar Subject: [PATCH bpf-next v3 3/3] bpf: Add a selftest for bpf_ima_inode_hash Date: Tue, 24 Nov 2020 15:12:10 +0000 Message-Id: <20201124151210.1081188-4-kpsingh@chromium.org> X-Mailer: git-send-email 2.29.2.454.gaff20da3a2-goog In-Reply-To: <20201124151210.1081188-1-kpsingh@chromium.org> References: <20201124151210.1081188-1-kpsingh@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: From: KP Singh The test does the following: - Mounts a loopback filesystem and appends the IMA policy to measure executions only on this file-system. Restricting the IMA policy to a particular filesystem prevents a system-wide IMA policy change. - Executes an executable copied to this loopback filesystem. - Calls the bpf_ima_inode_hash in the bprm_committed_creds hook and checks if the call succeeded and checks if a hash was calculated. The test shells out to the added ima_setup.sh script as the setup is better handled in a shell script and is more complicated to do in the test program or even shelling out individual commands from C. The list of required configs (i.e. IMA, SECURITYFS, IMA_{WRITE,READ}_POLICY) for running this test are also updated. Signed-off-by: KP Singh Acked-by: Yonghong Song --- tools/testing/selftests/bpf/config | 4 + tools/testing/selftests/bpf/ima_setup.sh | 80 +++++++++++++++++++ .../selftests/bpf/prog_tests/test_ima.c | 74 +++++++++++++++++ tools/testing/selftests/bpf/progs/ima.c | 28 +++++++ 4 files changed, 186 insertions(+) create mode 100644 tools/testing/selftests/bpf/ima_setup.sh create mode 100644 tools/testing/selftests/bpf/prog_tests/test_ima.c create mode 100644 tools/testing/selftests/bpf/progs/ima.c diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index 2118e23ac07a..365bf9771b07 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -39,3 +39,7 @@ CONFIG_BPF_JIT=y CONFIG_BPF_LSM=y CONFIG_SECURITY=y CONFIG_LIRC=y +CONFIG_IMA=y +CONFIG_SECURITYFS=y +CONFIG_IMA_WRITE_POLICY=y +CONFIG_IMA_READ_POLICY=y diff --git a/tools/testing/selftests/bpf/ima_setup.sh b/tools/testing/selftests/bpf/ima_setup.sh new file mode 100644 index 000000000000..15490ccc5e55 --- /dev/null +++ b/tools/testing/selftests/bpf/ima_setup.sh @@ -0,0 +1,80 @@ +#!/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 " + 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: ${action}" + exit 1 + fi +} + +main "$@" diff --git a/tools/testing/selftests/bpf/prog_tests/test_ima.c b/tools/testing/selftests/bpf/prog_tests/test_ima.c new file mode 100644 index 000000000000..61fca681d524 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_ima.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2020 Google LLC. + */ + +#include +#include +#include +#include +#include + +#include "ima.skel.h" + +static int run_measured_process(const char *measured_dir, u32 *monitored_pid) +{ + int child_pid, child_status; + + child_pid = fork(); + if (child_pid == 0) { + *monitored_pid = getpid(); + execlp("./ima_setup.sh", "./ima_setup.sh", "run", measured_dir, + NULL); + exit(errno); + + } else if (child_pid > 0) { + waitpid(child_pid, &child_status, 0); + return WEXITSTATUS(child_status); + } + + return -EINVAL; +} + +void test_test_ima(void) +{ + char measured_dir_template[] = "/tmp/ima_measuredXXXXXX"; + const char *measured_dir; + char cmd[256]; + + int err, duration = 0; + struct ima *skel = NULL; + + skel = ima__open_and_load(); + if (CHECK(!skel, "skel_load", "skeleton failed\n")) + goto close_prog; + + err = ima__attach(skel); + if (CHECK(err, "attach", "attach failed: %d\n", err)) + goto close_prog; + + measured_dir = mkdtemp(measured_dir_template); + if (CHECK(measured_dir == NULL, "mkdtemp", "err %d\n", errno)) + goto close_prog; + + snprintf(cmd, sizeof(cmd), "./ima_setup.sh setup %s", measured_dir); + if (CHECK_FAIL(system(cmd))) + goto close_clean; + + err = run_measured_process(measured_dir, &skel->bss->monitored_pid); + if (CHECK(err, "run_measured_process", "err = %d\n", err)) + goto close_clean; + + CHECK(skel->data->ima_hash_ret < 0, "ima_hash_ret", + "ima_hash_ret = %ld\n", skel->data->ima_hash_ret); + + CHECK(skel->bss->ima_hash == 0, "ima_hash", + "ima_hash = %lu\n", skel->bss->ima_hash); + +close_clean: + snprintf(cmd, sizeof(cmd), "./ima_setup.sh cleanup %s", measured_dir); + CHECK_FAIL(system(cmd)); +close_prog: + ima__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/ima.c b/tools/testing/selftests/bpf/progs/ima.c new file mode 100644 index 000000000000..86b21aff4bc5 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/ima.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright 2020 Google LLC. + */ + +#include "vmlinux.h" +#include +#include +#include + +long ima_hash_ret = -1; +u64 ima_hash = 0; +u32 monitored_pid = 0; + +char _license[] SEC("license") = "GPL"; + +SEC("lsm.s/bprm_committed_creds") +int BPF_PROG(ima, struct linux_binprm *bprm) +{ + u32 pid = bpf_get_current_pid_tgid() >> 32; + + if (pid == monitored_pid) + ima_hash_ret = bpf_ima_inode_hash(bprm->file->f_inode, + &ima_hash, sizeof(ima_hash)); + + return 0; +}