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 <uapi/linux/unistd.h>
  12#include "syscall_nrs.h"
  13#include <bpf/bpf_helpers.h>
  14#include <bpf/bpf_tracing.h>
  15
  16#define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
  17
  18struct {
  19        __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
  20        __uint(key_size, sizeof(u32));
  21        __uint(value_size, sizeof(u32));
  22#ifdef __mips__
  23        __uint(max_entries, 6000); /* MIPS n64 syscalls start at 5000 */
  24#else
  25        __uint(max_entries, 1024);
  26#endif
  27} progs SEC(".maps");
  28
  29SEC("kprobe/__seccomp_filter")
  30int bpf_prog1(struct pt_regs *ctx)
  31{
  32        int sc_nr = (int)PT_REGS_PARM1(ctx);
  33
  34        /* dispatch into next BPF program depending on syscall number */
  35        bpf_tail_call(ctx, &progs, sc_nr);
  36
  37        /* fall through -> unknown syscall */
  38        if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
  39                char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
  40                bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
  41        }
  42        return 0;
  43}
  44
  45/* we jump here when syscall number == __NR_write */
  46PROG(SYS__NR_write)(struct pt_regs *ctx)
  47{
  48        struct seccomp_data sd;
  49
  50        bpf_probe_read_kernel(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
  51        if (sd.args[2] == 512) {
  52                char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
  53                bpf_trace_printk(fmt, sizeof(fmt),
  54                                 sd.args[0], sd.args[1], sd.args[2]);
  55        }
  56        return 0;
  57}
  58
  59PROG(SYS__NR_read)(struct pt_regs *ctx)
  60{
  61        struct seccomp_data sd;
  62
  63        bpf_probe_read_kernel(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
  64        if (sd.args[2] > 128 && sd.args[2] <= 1024) {
  65                char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
  66                bpf_trace_printk(fmt, sizeof(fmt),
  67                                 sd.args[0], sd.args[1], sd.args[2]);
  68        }
  69        return 0;
  70}
  71
  72#ifdef __NR_mmap2
  73PROG(SYS__NR_mmap2)(struct pt_regs *ctx)
  74{
  75        char fmt[] = "mmap2\n";
  76
  77        bpf_trace_printk(fmt, sizeof(fmt));
  78        return 0;
  79}
  80#endif
  81
  82#ifdef __NR_mmap
  83PROG(SYS__NR_mmap)(struct pt_regs *ctx)
  84{
  85        char fmt[] = "mmap\n";
  86
  87        bpf_trace_printk(fmt, sizeof(fmt));
  88        return 0;
  89}
  90#endif
  91
  92char _license[] SEC("license") = "GPL";
  93u32 _version SEC("version") = LINUX_VERSION_CODE;
  94