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Message-Id: <20201124151210.1081188-4-kpsingh@chromium.org>
Date: Tue, 24 Nov 2020 15:12:10 +0000
From: KP Singh <kpsingh@...omium.org>
To: 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: [PATCH bpf-next v3 3/3] bpf: Add a selftest for bpf_ima_inode_hash
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);
+
+ } 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 <errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+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;
+}
--
2.29.2.454.gaff20da3a2-goog
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