text: /* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   */
  #include <linux/ptrace.h>
  #include <linux/version.h>
  #include <uapi/linux/bpf.h>
  #include <uapi/linux/seccomp.h>
  #include <uapi/linux/unistd.h>
  #include "syscall_nrs.h"
  #include "bpf_helpers.h"
  
  #define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
  
  struct bpf_map_def SEC("maps") progs = {
  	.type = BPF_MAP_TYPE_PROG_ARRAY,
  	.key_size = sizeof(u32),
  	.value_size = sizeof(u32),
  #ifdef __mips__
  	.max_entries = 6000, /* MIPS n64 syscalls start at 5000 */
  #else
  	.max_entries = 1024,
  #endif
  };
  
  SEC("kprobe/__seccomp_filter")
  int bpf_prog1(struct pt_regs *ctx)
  {
  	int sc_nr = (int)PT_REGS_PARM1(ctx);
  
  	/* dispatch into next BPF program depending on syscall number */
  	bpf_tail_call(ctx, &progs, sc_nr);
  
  	/* fall through -> unknown syscall */
  	if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
  		char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
  		bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
  	}
  	return 0;
  }
  
  /* we jump here when syscall number == __NR_write */
  PROG(SYS__NR_write)(struct pt_regs *ctx)
  {
  	struct seccomp_data sd;
  
  	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
  	if (sd.args[2] == 512) {
  		char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
  		bpf_trace_printk(fmt, sizeof(fmt),
  				 sd.args[0], sd.args[1], sd.args[2]);
  	}
  	return 0;
  }
  
  PROG(SYS__NR_read)(struct pt_regs *ctx)
  {
  	struct seccomp_data sd;
  
  	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
  	if (sd.args[2] > 128 && sd.args[2] <= 1024) {
  		char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
  		bpf_trace_printk(fmt, sizeof(fmt),
  				 sd.args[0], sd.args[1], sd.args[2]);
  	}
  	return 0;
  }
  
  #ifdef __NR_mmap2
  PROG(SYS__NR_mmap2)(struct pt_regs *ctx)
  {
  	char fmt[] = "mmap2\n";
  
  	bpf_trace_printk(fmt, sizeof(fmt));
  	return 0;
  }
  #endif
  
  #ifdef __NR_mmap
  PROG(SYS__NR_mmap)(struct pt_regs *ctx)
  {
  	char fmt[] = "mmap\n";
  
  	bpf_trace_printk(fmt, sizeof(fmt));
  	return 0;
  }
  #endif
  
  char _license[] SEC("license") = "GPL";
  u32 _version SEC("version") = LINUX_VERSION_CODE;
  