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")
BPF_PROG(d_path_check_rdonly_mem,struct path * path,struct kstat * stat,__u32 request_mask,unsigned int query_flags)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