// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH * * Author: Roberto Sassu <roberto.sassu@huawei.com> */ #include "vmlinux.h" #include <errno.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> /* From include/linux/mm.h. */ #define FMODE_WRITE 0x2 struct { __uint(type, BPF_MAP_TYPE_ARRAY); __uint(max_entries, 1); __type(key, __u32); __type(value, __u32); } data_input SEC(".maps"); char _license[] SEC("license") = "GPL"; SEC("lsm/bpf_map") int BPF_PROG(check_access, struct bpf_map *map, fmode_t fmode) { if (map != (struct bpf_map *)&data_input) return 0; if (fmode & FMODE_WRITE) return -EACCES; barrier(); return 0; }