| // 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; |
| |
| return 0; |
| } |
