From patchwork Wed Mar 2 11:14:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12765782 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91F44C433F5 for ; Wed, 2 Mar 2022 11:18:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236877AbiCBLS7 (ORCPT ); Wed, 2 Mar 2022 06:18:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241738AbiCBLSf (ORCPT ); Wed, 2 Mar 2022 06:18:35 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B037AC4B69; Wed, 2 Mar 2022 03:16:04 -0800 (PST) Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4K7s2j4DqTz67r9d; Wed, 2 Mar 2022 19:14:37 +0800 (CST) Received: from roberto-ThinkStation-P620.huawei.com (10.204.63.22) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 2 Mar 2022 12:15:49 +0100 From: Roberto Sassu To: , , , , , , , , CC: , , , , , , Roberto Sassu Subject: [PATCH v3 6/9] selftests/bpf: Check if the digest is refreshed after a file write Date: Wed, 2 Mar 2022 12:14:01 +0100 Message-ID: <20220302111404.193900-7-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220302111404.193900-1-roberto.sassu@huawei.com> References: <20220302111404.193900-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.63.22] X-ClientProxiedBy: lhreml751-chm.china.huawei.com (10.201.108.201) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Verify that bpf_ima_inode_hash() returns a non-fresh digest after a file write, and that bpf_ima_file_hash() returns a fresh digest. Verification is done by requesting the digest from the bprm_creds_for_exec hook, called before ima_bprm_check(). Signed-off-by: Roberto Sassu --- tools/testing/selftests/bpf/ima_setup.sh | 24 ++++++- .../selftests/bpf/prog_tests/test_ima.c | 72 ++++++++++++++++++- tools/testing/selftests/bpf/progs/ima.c | 11 +++ 3 files changed, 103 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/ima_setup.sh b/tools/testing/selftests/bpf/ima_setup.sh index 8e62581113a3..a3de1cd43ba0 100755 --- a/tools/testing/selftests/bpf/ima_setup.sh +++ b/tools/testing/selftests/bpf/ima_setup.sh @@ -12,7 +12,7 @@ LOG_FILE="$(mktemp /tmp/ima_setup.XXXX.log)" usage() { - echo "Usage: $0 " + echo "Usage: $0 " exit 1 } @@ -77,6 +77,24 @@ run() exec "${copied_bin_path}" } +modify_bin() +{ + local tmp_dir="$1" + local mount_dir="${tmp_dir}/mnt" + local copied_bin_path="${mount_dir}/$(basename ${TEST_BINARY})" + + echo "mod" >> "${copied_bin_path}" +} + +restore_bin() +{ + local tmp_dir="$1" + local mount_dir="${tmp_dir}/mnt" + local copied_bin_path="${mount_dir}/$(basename ${TEST_BINARY})" + + truncate -s -4 "${copied_bin_path}" +} + catch() { local exit_code="$1" @@ -105,6 +123,10 @@ main() cleanup "${tmp_dir}" elif [[ "${action}" == "run" ]]; then run "${tmp_dir}" + elif [[ "${action}" == "modify-bin" ]]; then + modify_bin "${tmp_dir}" + elif [[ "${action}" == "restore-bin" ]]; then + restore_bin "${tmp_dir}" else echo "Unknown action: ${action}" exit 1 diff --git a/tools/testing/selftests/bpf/prog_tests/test_ima.c b/tools/testing/selftests/bpf/prog_tests/test_ima.c index acc911ba63fd..a0cfba0b4273 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_ima.c +++ b/tools/testing/selftests/bpf/prog_tests/test_ima.c @@ -13,16 +13,17 @@ #include "ima.skel.h" -#define MAX_SAMPLES 2 +#define MAX_SAMPLES 4 -static int run_measured_process(const char *measured_dir, u32 *monitored_pid) +static int _run_measured_process(const char *measured_dir, u32 *monitored_pid, + const char *cmd) { 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, + execlp("./ima_setup.sh", "./ima_setup.sh", cmd, measured_dir, NULL); exit(errno); @@ -34,6 +35,11 @@ static int run_measured_process(const char *measured_dir, u32 *monitored_pid) return -EINVAL; } +static int run_measured_process(const char *measured_dir, u32 *monitored_pid) +{ + return _run_measured_process(measured_dir, monitored_pid, "run"); +} + static u64 ima_hash_from_bpf[MAX_SAMPLES]; static int ima_hash_from_bpf_idx; @@ -51,6 +57,7 @@ static void test_init(struct ima__bss *bss) ima_hash_from_bpf_idx = 0; bss->use_ima_file_hash = false; + bss->enable_bprm_creds_for_exec = false; } void test_test_ima(void) @@ -58,6 +65,7 @@ void test_test_ima(void) char measured_dir_template[] = "/tmp/ima_measuredXXXXXX"; struct ring_buffer *ringbuf = NULL; const char *measured_dir; + u64 bin_true_sample; char cmd[256]; int err, duration = 0; @@ -114,6 +122,64 @@ void test_test_ima(void) ASSERT_EQ(err, 2, "num_samples_or_err"); ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash"); ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash"); + bin_true_sample = ima_hash_from_bpf[1]; + + /* + * Test #3 + * - Goal: confirm that bpf_ima_inode_hash() returns a non-fresh digest + * - Expected result: 2 samples (/bin/true: non-fresh, fresh) + */ + test_init(skel->bss); + + err = _run_measured_process(measured_dir, &skel->bss->monitored_pid, + "modify-bin"); + if (CHECK(err, "modify-bin #3", "err = %d\n", err)) + goto close_clean; + + skel->bss->enable_bprm_creds_for_exec = true; + err = run_measured_process(measured_dir, &skel->bss->monitored_pid); + if (CHECK(err, "run_measured_process #3", "err = %d\n", err)) + goto close_clean; + + err = ring_buffer__consume(ringbuf); + ASSERT_EQ(err, 2, "num_samples_or_err"); + ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash"); + ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash"); + ASSERT_EQ(ima_hash_from_bpf[0], bin_true_sample, "sample_equal_or_err"); + /* IMA refreshed the digest. */ + ASSERT_NEQ(ima_hash_from_bpf[1], bin_true_sample, + "sample_different_or_err"); + + /* + * Test #4 + * - Goal: verify that bpf_ima_file_hash() returns a fresh digest + * - Expected result: 4 samples (./ima_setup.sh: fresh, fresh; + * /bin/true: fresh, fresh) + */ + test_init(skel->bss); + skel->bss->use_ima_file_hash = true; + skel->bss->enable_bprm_creds_for_exec = true; + err = run_measured_process(measured_dir, &skel->bss->monitored_pid); + if (CHECK(err, "run_measured_process #4", "err = %d\n", err)) + goto close_clean; + + err = ring_buffer__consume(ringbuf); + ASSERT_EQ(err, 4, "num_samples_or_err"); + ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash"); + ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash"); + ASSERT_NEQ(ima_hash_from_bpf[2], 0, "ima_hash"); + ASSERT_NEQ(ima_hash_from_bpf[3], 0, "ima_hash"); + ASSERT_NEQ(ima_hash_from_bpf[2], bin_true_sample, + "sample_different_or_err"); + ASSERT_EQ(ima_hash_from_bpf[3], ima_hash_from_bpf[2], + "sample_equal_or_err"); + + skel->bss->use_ima_file_hash = false; + skel->bss->enable_bprm_creds_for_exec = false; + err = _run_measured_process(measured_dir, &skel->bss->monitored_pid, + "restore-bin"); + if (CHECK(err, "restore-bin #3", "err = %d\n", err)) + goto close_clean; close_clean: snprintf(cmd, sizeof(cmd), "./ima_setup.sh cleanup %s", measured_dir); diff --git a/tools/testing/selftests/bpf/progs/ima.c b/tools/testing/selftests/bpf/progs/ima.c index e0b073dcfb5d..9633e5f2453d 100644 --- a/tools/testing/selftests/bpf/progs/ima.c +++ b/tools/testing/selftests/bpf/progs/ima.c @@ -19,6 +19,7 @@ struct { char _license[] SEC("license") = "GPL"; bool use_ima_file_hash; +bool enable_bprm_creds_for_exec; static void ima_test_common(struct file *file) { @@ -54,3 +55,13 @@ void BPF_PROG(bprm_committed_creds, struct linux_binprm *bprm) { ima_test_common(bprm->file); } + +SEC("lsm.s/bprm_creds_for_exec") +int BPF_PROG(bprm_creds_for_exec, struct linux_binprm *bprm) +{ + if (!enable_bprm_creds_for_exec) + return 0; + + ima_test_common(bprm->file); + return 0; +}