sandbox/linux/bpf_dsl/dump_bpf.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "sandbox/linux/bpf_dsl/dump_bpf.h"
   6
   7 #include <stdio.h>
   8
   9 #include "sandbox/linux/bpf_dsl/codegen.h"
  10 #include "sandbox/linux/bpf_dsl/trap_registry.h"
  11 #include "sandbox/linux/system_headers/linux_filter.h"
  12 #include "sandbox/linux/system_headers/linux_seccomp.h"
  13
  14 namespace sandbox {
  15 namespace bpf_dsl {
  16
  17 void DumpBPF::PrintProgram(const CodeGen::Program& program) {
  18   for (CodeGen::Program::const_iterator iter = program.begin();
  19        iter != program.end();
  20        ++iter) {
  21     int ip = (int)(iter - program.begin());
  22     fprintf(stderr, "%3d) ", ip);
  23     switch (BPF_CLASS(iter->code)) {
  24       case BPF_LD:
  25         if (iter->code == BPF_LD + BPF_W + BPF_ABS) {
  26           fprintf(stderr, "LOAD %d  // ", (int)iter->k);
  27           if (iter->k == offsetof(struct arch_seccomp_data, nr)) {
  28             fprintf(stderr, "System call number\n");
  29           } else if (iter->k == offsetof(struct arch_seccomp_data, arch)) {
  30             fprintf(stderr, "Architecture\n");
  31           } else if (iter->k ==
  32                      offsetof(struct arch_seccomp_data, instruction_pointer)) {
  33             fprintf(stderr, "Instruction pointer (LSB)\n");
  34           } else if (iter->k ==
  35                      offsetof(struct arch_seccomp_data, instruction_pointer) +
  36                          4) {
  37             fprintf(stderr, "Instruction pointer (MSB)\n");
  38           } else if (iter->k >= offsetof(struct arch_seccomp_data, args) &&
  39                      iter->k < offsetof(struct arch_seccomp_data, args) + 48 &&
  40                      (iter->k - offsetof(struct arch_seccomp_data, args)) % 4 ==
  41                          0) {
  42             fprintf(
  43                 stderr,
  44                 "Argument %d (%cSB)\n",
  45                 (int)(iter->k - offsetof(struct arch_seccomp_data, args)) / 8,
  46                 (iter->k - offsetof(struct arch_seccomp_data, args)) % 8 ? 'M'
  47                                                                          : 'L');
  48           } else {
  49             fprintf(stderr, "???\n");
  50           }
  51         } else {
  52           fprintf(stderr, "LOAD ???\n");
  53         }
  54         break;
  55       case BPF_JMP:
  56         if (BPF_OP(iter->code) == BPF_JA) {
  57           fprintf(stderr, "JMP %d\n", ip + iter->k + 1);
  58         } else {
  59           fprintf(stderr, "if A %s 0x%x; then JMP %d else JMP %d\n",
  60               BPF_OP(iter->code) == BPF_JSET ? "&" :
  61               BPF_OP(iter->code) == BPF_JEQ ? "==" :
  62               BPF_OP(iter->code) == BPF_JGE ? ">=" :
  63               BPF_OP(iter->code) == BPF_JGT ? ">"  : "???",
  64               (int)iter->k,
  65               ip + iter->jt + 1, ip + iter->jf + 1);
  66         }
  67         break;
  68       case BPF_RET:
  69         fprintf(stderr, "RET 0x%x  // ", iter->k);
  70         if ((iter->k & SECCOMP_RET_ACTION) == SECCOMP_RET_TRAP) {
  71           fprintf(stderr, "Trap #%d\n", iter->k & SECCOMP_RET_DATA);
  72         } else if ((iter->k & SECCOMP_RET_ACTION) == SECCOMP_RET_ERRNO) {
  73           fprintf(stderr, "errno = %d\n", iter->k & SECCOMP_RET_DATA);
  74         } else if ((iter->k & SECCOMP_RET_ACTION) == SECCOMP_RET_TRACE) {
  75           fprintf(stderr, "Trace #%d\n", iter->k & SECCOMP_RET_DATA);
  76         } else if (iter->k == SECCOMP_RET_ALLOW) {
  77           fprintf(stderr, "Allowed\n");
  78         } else {
  79           fprintf(stderr, "???\n");
  80         }
  81         break;
  82       case BPF_ALU:
  83         if (BPF_OP(iter->code) == BPF_NEG) {
  84           fprintf(stderr, "A := -A\n");
  85         } else {
  86           fprintf(stderr, "A := A %s 0x%x\n",
  87                   BPF_OP(iter->code) == BPF_ADD ? "+"  :
  88                   BPF_OP(iter->code) == BPF_SUB ? "-"  :
  89                   BPF_OP(iter->code) == BPF_MUL ? "*"  :
  90                   BPF_OP(iter->code) == BPF_DIV ? "/"  :
  91                   BPF_OP(iter->code) == BPF_MOD ? "%"  :
  92                   BPF_OP(iter->code) == BPF_OR  ? "|"  :
  93                   BPF_OP(iter->code) == BPF_XOR ? "^"  :
  94                   BPF_OP(iter->code) == BPF_AND ? "&"  :
  95                   BPF_OP(iter->code) == BPF_LSH ? "<<" :
  96                   BPF_OP(iter->code) == BPF_RSH ? ">>" : "???",
  97                   (int)iter->k);
  98         }
  99         break;
 100       default:
 101         fprintf(stderr, "???\n");
 102         break;
 103     }
 104   }
 105   return;
 106 }
 107
 108 }  // namespace bpf_dsl
 109 }  // namespace sandbox