From 341f06fdddf72cd60a10945152f69f0f1d614519 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 29 Nov 2023 15:44:16 -0800 Subject: selftests/bpf: Add tests for filesystem kfuncs Add selftests for two new filesystem kfuncs: 1. bpf_get_file_xattr 2. bpf_get_fsverity_digest These tests simply make sure the two kfuncs work. Another selftest will be added to demonstrate how to use these kfuncs to verify file signature. CONFIG_FS_VERITY is added to selftests config. However, this is not sufficient to guarantee bpf_get_fsverity_digest works. This is because fsverity need to be enabled at file system level (for example, with tune2fs on ext4). If local file system doesn't have this feature enabled, just skip the test. Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231129234417.856536-6-song@kernel.org Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/progs/test_fsverity.c | 48 +++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/test_fsverity.c (limited to 'tools/testing/selftests/bpf/progs/test_fsverity.c') diff --git a/tools/testing/selftests/bpf/progs/test_fsverity.c b/tools/testing/selftests/bpf/progs/test_fsverity.c new file mode 100644 index 000000000000..3975495b75c8 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_fsverity.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ + +#include "vmlinux.h" +#include +#include +#include "bpf_kfuncs.h" + +char _license[] SEC("license") = "GPL"; + +#ifndef SHA256_DIGEST_SIZE +#define SHA256_DIGEST_SIZE 32 +#endif + +#define SIZEOF_STRUCT_FSVERITY_DIGEST 4 /* sizeof(struct fsverity_digest) */ + +char expected_digest[SIZEOF_STRUCT_FSVERITY_DIGEST + SHA256_DIGEST_SIZE]; +char digest[SIZEOF_STRUCT_FSVERITY_DIGEST + SHA256_DIGEST_SIZE]; +__u32 monitored_pid; +__u32 got_fsverity; +__u32 digest_matches; + +SEC("lsm.s/file_open") +int BPF_PROG(test_file_open, struct file *f) +{ + struct bpf_dynptr digest_ptr; + __u32 pid; + int ret; + int i; + + pid = bpf_get_current_pid_tgid() >> 32; + if (pid != monitored_pid) + return 0; + + bpf_dynptr_from_mem(digest, sizeof(digest), 0, &digest_ptr); + ret = bpf_get_fsverity_digest(f, &digest_ptr); + if (ret < 0) + return 0; + got_fsverity = 1; + + for (i = 0; i < sizeof(digest); i++) { + if (digest[i] != expected_digest[i]) + return 0; + } + + digest_matches = 1; + return 0; +} -- cgit