1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (c) 2022 Google */ |
3 | |
4 | #include "vmlinux.h" |
5 | #include <bpf/bpf_helpers.h> |
6 | #include <bpf/bpf_tracing.h> |
7 | |
8 | extern const int bpf_prog_active __ksym; |
9 | |
10 | SEC("fentry/security_inode_getattr" ) |
11 | int BPF_PROG(d_path_check_rdonly_mem, struct path *path, struct kstat *stat, |
12 | __u32 request_mask, unsigned int query_flags) |
13 | { |
14 | void *active; |
15 | __u32 cpu; |
16 | |
17 | cpu = bpf_get_smp_processor_id(); |
18 | active = (void *)bpf_per_cpu_ptr(&bpf_prog_active, cpu); |
19 | if (active) { |
20 | /* FAIL here! 'active' points to readonly memory. bpf helpers |
21 | * that update its arguments can not write into it. |
22 | */ |
23 | bpf_d_path(path, active, sizeof(int)); |
24 | } |
25 | return 0; |
26 | } |
27 | |
28 | char _license[] SEC("license" ) = "GPL" ; |
29 | |