tools/testing/selftests/bpf/progs/test_d_path_check_rdonly_mem.c

   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";