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1// SPDX-License-Identifier: GPL-2.02/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */3 4#include "vmlinux.h"5#include <bpf/bpf_helpers.h>6#include <bpf/bpf_tracing.h>7#include "bpf_kfuncs.h"8 9char _license[] SEC("license") = "GPL";10 11#ifndef SHA256_DIGEST_SIZE12#define SHA256_DIGEST_SIZE 3213#endif14 15#define SIZEOF_STRUCT_FSVERITY_DIGEST 4 /* sizeof(struct fsverity_digest) */16 17char expected_digest[SIZEOF_STRUCT_FSVERITY_DIGEST + SHA256_DIGEST_SIZE];18char digest[SIZEOF_STRUCT_FSVERITY_DIGEST + SHA256_DIGEST_SIZE];19__u32 monitored_pid;20__u32 got_fsverity;21__u32 digest_matches;22 23SEC("lsm.s/file_open")24int BPF_PROG(test_file_open, struct file *f)25{26 struct bpf_dynptr digest_ptr;27 __u32 pid;28 int ret;29 int i;30 31 pid = bpf_get_current_pid_tgid() >> 32;32 if (pid != monitored_pid)33 return 0;34 35 bpf_dynptr_from_mem(digest, sizeof(digest), 0, &digest_ptr);36 ret = bpf_get_fsverity_digest(f, &digest_ptr);37 if (ret < 0)38 return 0;39 got_fsverity = 1;40 41 for (i = 0; i < (int)sizeof(digest); i++) {42 if (digest[i] != expected_digest[i])43 return 0;44 }45 46 digest_matches = 1;47 return 0;48}49