LXR linux/samples/bpf/tracex5

   1/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 */
   7#include <linux/ptrace.h>
   8#include <linux/version.h>
   9#include <uapi/linux/bpf.h>
  10#include <uapi/linux/seccomp.h>
  11#include "bpf_helpers.h"
  12
  13#define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
  14
  15struct bpf_map_def SEC("maps") progs = {
  16        .type = BPF_MAP_TYPE_PROG_ARRAY,
  17        .key_size = sizeof(u32),
  18        .value_size = sizeof(u32),
  19        .max_entries = 1024,
  20};
  21
  22SEC("kprobe/seccomp_phase1")
  23int bpf_prog1(struct pt_regs *ctx)
  24{
  25        struct seccomp_data sd = {};
  26
  27        bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
  28
  29        /* dispatch into next BPF program depending on syscall number */
  30        bpf_tail_call(ctx, &progs, sd.nr);
  31
  32        /* fall through -> unknown syscall */
  33        if (sd.nr >= __NR_getuid && sd.nr <= __NR_getsid) {
  34                char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
  35                bpf_trace_printk(fmt, sizeof(fmt), sd.nr);
  36        }
  37        return 0;
  38}
  39
  40/* we jump here when syscall number == __NR_write */
  41PROG(__NR_write)(struct pt_regs *ctx)
  42{
  43        struct seccomp_data sd = {};
  44
  45        bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
  46        if (sd.args[2] == 512) {
  47                char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
  48                bpf_trace_printk(fmt, sizeof(fmt),
  49                                 sd.args[0], sd.args[1], sd.args[2]);
  50        }
  51        return 0;
  52}
  53
  54PROG(__NR_read)(struct pt_regs *ctx)
  55{
  56        struct seccomp_data sd = {};
  57
  58        bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
  59        if (sd.args[2] > 128 && sd.args[2] <= 1024) {
  60                char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
  61                bpf_trace_printk(fmt, sizeof(fmt),
  62                                 sd.args[0], sd.args[1], sd.args[2]);
  63        }
  64        return 0;
  65}
  66
  67PROG(__NR_mmap)(struct pt_regs *ctx)
  68{
  69        char fmt[] = "mmap\n";
  70        bpf_trace_printk(fmt, sizeof(fmt));
  71        return 0;
  72}
  73
  74char _license[] SEC("license") = "GPL";
  75u32 _version SEC("version") = LINUX_VERSION_CODE;
  76