// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ #include "vmlinux.h" #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> #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 < (int)sizeof(digest); i++) { if (digest[i] != expected_digest[i]) return 0; } digest_matches = 1; return 0; }