bpf/progs/test_d_path_check_rdonly_mem.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /* Copyright (c) 2022 Google */
0003
0004 #include "vmlinux.h"
0005 #include <bpf/bpf_helpers.h>
0006 #include <bpf/bpf_tracing.h>
0007
0008 extern const int bpf_prog_active __ksym;
0009
0010 SEC("fentry/security_inode_getattr")
0011 int BPF_PROG(d_path_check_rdonly_mem, struct path *path, struct kstat *stat,
0012          __u32 request_mask, unsigned int query_flags)
0013 {
0014     void *active;
0015     __u32 cpu;
0016
0017     cpu = bpf_get_smp_processor_id();
0018     active = (void *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
0019     if (active) {
0020         /* FAIL here! 'active' points to readonly memory. bpf helpers
0021          * that update its arguments can not write into it.
0022          */
0023         bpf_d_path(path, active, sizeof(int));
0024     }
0025     return 0;
0026 }
0027
0028 char _license[] SEC("license") = "GPL";