src/native_client/src/trusted/validator/x86/ncval_reg_sfi/nc_postconds.c

   1 /*
   2  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
   3  * Use of this source code is governed by a BSD-style license that can be
   4  * found in the LICENSE file.
   5  */
   6
   7 #include "native_client/src/trusted/validator/x86/ncval_reg_sfi/nc_postconds.h"
   8
   9 #include "native_client/src/include/portability_io.h"
  10 #include "native_client/src/shared/platform/nacl_log.h"
  11 #include "native_client/src/trusted/validator/x86/decoder/ncop_exps.h"
  12 #include "native_client/src/trusted/validator/x86/decoder/nc_inst_state.h"
  13 #include "native_client/src/trusted/validator/x86/decoder/nc_inst_trans.h"
  14 #include "native_client/src/trusted/validator/x86/ncval_reg_sfi/ncvalidate_iter.h"
  15 #include "native_client/src/trusted/validator/x86/ncval_reg_sfi/ncvalidate_iter_internal.h"
  16 #include "native_client/src/trusted/validator/x86/ncval_reg_sfi/ncvalidate_utils.h"
  17 #include "native_client/src/trusted/validator/x86/ncval_reg_sfi/nc_memory_protect.h"
  18
  19 /* To turn on debugging of instruction decoding, change value of
  20  * DEBUGGING to 1.
  21  */
  22 #define DEBUGGING 0
  23
  24 #include "native_client/src/shared/utils/debugging.h"
  25
  26 #include "native_client/src/trusted/validator/x86/decoder/ncop_exps_inl.c"
  27
  28 /* Maximum character buffer size to use for generating messages. */
  29 static const size_t kMaxBufferSize = 1024;
  30
  31 #ifdef NCVAL_TESTING
  32 void NaClAddAssignsRegisterWithZeroExtendsPostconds(
  33     struct NaClValidatorState* state) {
  34   uint32_t i;
  35   NaClExpVector* vector = state->cur_inst_vector;
  36
  37   DEBUG(NaClValidatorInstMessage(
  38       LOG_INFO, state, state->cur_inst_state,
  39       "-> Checking ZeroExtends postconditions...\n"));
  40
  41   /* Look for assignments to 32-bit registers for instructions that
  42    * zero extend.
  43    */
  44   for (i = 0; i < vector->number_expr_nodes; ++i) {
  45     NaClExp* node = &vector->node[i];
  46     NaClOpKind node_reg;
  47     if (ExprRegister != node->kind) continue;
  48     if (!NaClHasBit(node->flags, NACL_EFLAG(ExprSet))) continue;
  49     if (!NaClHasBit(node->flags, NACL_EFLAG(ExprSize32))) continue;
  50     node_reg = NaClGetExpRegisterInline(node);
  51     if (node_reg == RegUnknown) continue;
  52     if (NaClAssignsRegisterWithZeroExtends32(state, 0, node_reg)) {
  53       char* buffer;
  54       size_t buffer_size;
  55       char reg_name[kMaxBufferSize];
  56       NaClOpRegName(node_reg, reg_name, kMaxBufferSize);
  57       NaClConditionAppend(state->postcond, &buffer, &buffer_size);
  58       SNPRINTF(buffer, buffer_size, "ZeroExtends(%s)", reg_name);
  59     }
  60   }
  61   DEBUG(NaClValidatorMessage(
  62       LOG_INFO, state, "<- Finished ZeroExtends postconditions...\n"));
  63 }
  64
  65 void NaClAddLeaSafeAddressPostconds(
  66     struct NaClValidatorState* state) {
  67   uint32_t i;
  68   NaClExpVector* vector = state->cur_inst_vector;
  69   DEBUG(NaClValidatorInstMessage(
  70       LOG_INFO, state, state->cur_inst_state,
  71       "Checking SafeAddress postconditions...\n"));
  72
  73   /* Look for assignments to registers. */
  74   for (i = 0; i < vector->number_expr_nodes; ++i) {
  75     NaClOpKind reg;
  76     NaClExp* node = &vector->node[i];
  77     if (ExprRegister != node->kind) continue;
  78     if (!NaClHasBit(node->flags, NACL_EFLAG(ExprSet))) continue;
  79     if (!NaClHasBit(node->flags, NACL_EFLAG(ExprSize64))) continue;
  80     reg = NaClGetExpRegisterInline(node);
  81     if (RegUnknown == reg) continue;
  82     if ((reg == RegRSP) || (reg == RegRBP)) {
  83       /* Note: Do not need to check safe addresses computed
  84        * by "LEA Rsp/Rbp ...". Currently, these two registers
  85        * are already checked.. See NaClCheckRspAssignments and
  86        * NaClCheckRbpAssignments in nc_protect_base.c for more
  87        * information on how such LEA instructions are checked.
  88        */
  89       if (InstLea != NaClInstStateInst(state->cur_inst_state)->name) {
  90         NaClAcceptLeaWithMoveLea32To64(state, reg);
  91       }
  92     } else if (NaClAcceptLeaSafeAddress(state)) {
  93       char* buffer;
  94       size_t buffer_size;
  95       char reg_name[kMaxBufferSize];
  96       NaClOpRegName(reg, reg_name, kMaxBufferSize);
  97       NaClConditionAppend(state->postcond, &buffer, &buffer_size);
  98       SNPRINTF(buffer, buffer_size, "SafeAddress(%s)", reg_name);
  99     }
 100   }
 101   DEBUG(NaClValidatorMessage(
 102       LOG_INFO, state, "Finished SafeAddress postconditions...\n"));
 103 }
 104
 105 #endif