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