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Message-ID: <a5c2244f-c733-ef78-7347-ac0a2a6bb77f@fb.com>
Date: Wed, 25 Nov 2020 22:27:47 -0800
From: Yonghong Song <yhs@...com>
To: KP Singh <kpsingh@...omium.org>, James Morris <jmorris@...ei.org>,
<linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
<linux-security-module@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Florent Revest <revest@...omium.org>,
Brendan Jackman <jackmanb@...omium.org>,
Mimi Zohar <zohar@...ux.ibm.com>
Subject: Re: [PATCH bpf-next v3 3/3] bpf: Add a selftest for
bpf_ima_inode_hash
On 11/24/20 7:12 AM, KP Singh wrote:
> From: KP Singh <kpsingh@...gle.com>
>
> 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 <kpsingh@...gle.com>
> ---
> 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 <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: ${action}"
> + exit 1
> + fi
> +}
> +
> +main "$@"
> 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 <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <sys/wait.h>
> +#include <test_progs.h>
> +
> +#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);
Running test_progs-no-alu32, the test failed as:
root@...h-fb-vm1:~/net-next/net-next/tools/testing/selftests/bpf
./test_progs-no_alu32 -t test_ima
sh: ./ima_setup.sh: No such file or directory
sh: ./ima_setup.sh: No such file or directory
test_test_ima:PASS:skel_load 0 nsec
test_test_ima:PASS:attach 0 nsec
test_test_ima:PASS:mkdtemp 0 nsec
test_test_ima:FAIL:56
test_test_ima:FAIL:71
#114 test_ima:FAIL
Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED
Although the file is indeed in this directory:
root@...h-fb-vm1:~/net-next/net-next/tools/testing/selftests/bpf ls
ima_setup.sh
ima_setup.sh
I think the execution actually tries to get file from
no_alu32 directory to avoid reusing the same files in
.../testing/selftests/bpf for -mcpu=v3 purpose.
The following change, which copies ima_setup.sh to
no_alu32 directory, seems fixing the issue:
TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c
\
network_helpers.c testing_helpers.c \
btf_helpers.c flow_dissector_load.h
TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read \
+ ima_setup.sh \
$(wildcard progs/btf_dump_test_case_*.c)
TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
Could you do a followup on this?
> +
> + } else if (child_pid > 0) {
> + waitpid(child_pid, &child_status, 0);
> + return WEXITSTATUS(child_status);
> + }
> +
> + return -EINVAL;
> +}
> +
[...]
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