The Tor Browser: security/sandbox/win/src/policy_engine

security/sandbox/win/src/policy_engine_opcodes.cc@b8a032363ba2 (annotated)

security/sandbox/win/src/policy_engine_opcodes.cc

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #include "sandbox/win/src/policy_engine_opcodes.h"
 #include "base/basictypes.h"
 #include "sandbox/win/src/sandbox_nt_types.h"
 #include "sandbox/win/src/sandbox_types.h"
 namespace {
 const unsigned short kMaxUniStrSize = 0xfffc;
 bool InitStringUnicode(const wchar_t* source, size_t length,
                        UNICODE_STRING* ustring) {
   ustring->Buffer = const_cast<wchar_t*>(source);
   ustring->Length = static_cast<USHORT>(length) * sizeof(wchar_t);
   if (length > kMaxUniStrSize) {
       return false;
   }
   ustring->MaximumLength = (NULL != source) ?
                                 ustring->Length + sizeof(wchar_t) : 0;
   return true;
 }
 }  // namespace
 namespace sandbox {
 SANDBOX_INTERCEPT NtExports g_nt;
 // Note: The opcodes are implemented as functions (as opposed to classes derived
 // from PolicyOpcode) because you should not add more member variables to the
 // PolicyOpcode class since it would cause object slicing on the target. So to
 // enforce that (instead of just trusting the developer) the opcodes became
 // just functions.
 //
 // In the code that follows I have keep the evaluation function and the factory
 // function together to stress the close relationship between both. For example,
 // only the factory method and the evaluation function know the stored argument
 // order and meaning.
 template <int>
 EvalResult OpcodeEval(PolicyOpcode* opcode, const ParameterSet* pp,
                       MatchContext* match);
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpAlwaysFalse:
 // Does not require input parameter.
 PolicyOpcode* OpcodeFactory::MakeOpAlwaysFalse(uint32 options) {
   return MakeBase(OP_ALWAYS_FALSE, options, -1);
 }
 template <>
 EvalResult OpcodeEval<OP_ALWAYS_FALSE>(PolicyOpcode* opcode,
                                        const ParameterSet* param,
                                        MatchContext* context) {
   UNREFERENCED_PARAMETER(opcode);
   UNREFERENCED_PARAMETER(param);
   UNREFERENCED_PARAMETER(context);
   return EVAL_FALSE;
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpAlwaysTrue:
 // Does not require input parameter.
 PolicyOpcode* OpcodeFactory::MakeOpAlwaysTrue(uint32 options) {
   return MakeBase(OP_ALWAYS_TRUE, options, -1);
 }
 template <>
 EvalResult OpcodeEval<OP_ALWAYS_TRUE>(PolicyOpcode* opcode,
                                       const ParameterSet* param,
                                       MatchContext* context) {
   UNREFERENCED_PARAMETER(opcode);
   UNREFERENCED_PARAMETER(param);
   UNREFERENCED_PARAMETER(context);
   return EVAL_TRUE;
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpAction:
 // Does not require input parameter.
 // Argument 0 contains the actual action to return.
 PolicyOpcode* OpcodeFactory::MakeOpAction(EvalResult action,
                                           uint32 options) {
   PolicyOpcode* opcode = MakeBase(OP_ACTION, options, 0);
   if (NULL == opcode) return NULL;
   opcode->SetArgument(0, action);
   return opcode;
 }
 template <>
 EvalResult OpcodeEval<OP_ACTION>(PolicyOpcode* opcode,
                                  const ParameterSet* param,
                                  MatchContext* context) {
   UNREFERENCED_PARAMETER(param);
   UNREFERENCED_PARAMETER(context);
   int action = 0;
   opcode->GetArgument(0, &action);
   return static_cast<EvalResult>(action);
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpNumberMatch:
 // Requires a unsigned long or void* in selected_param
 // Argument 0 is the stored number to match.
 // Argument 1 is the C++ type of the 0th argument.
 PolicyOpcode* OpcodeFactory::MakeOpNumberMatch(int16 selected_param,
                                                unsigned long match,
                                                uint32 options) {
   PolicyOpcode* opcode = MakeBase(OP_NUMBER_MATCH, options, selected_param);
   if (NULL == opcode) return NULL;
   opcode->SetArgument(0, match);
   opcode->SetArgument(1, ULONG_TYPE);
   return opcode;
 }
 PolicyOpcode* OpcodeFactory::MakeOpVoidPtrMatch(int16 selected_param,
                                                 const void* match,
                                                 uint32 options) {
   PolicyOpcode* opcode = MakeBase(OP_NUMBER_MATCH, options, selected_param);
   if (NULL == opcode) return NULL;
   opcode->SetArgument(0, match);
   opcode->SetArgument(1, VOIDPTR_TYPE);
   return opcode;
 }
 template <>
 EvalResult OpcodeEval<OP_NUMBER_MATCH>(PolicyOpcode* opcode,
                                        const ParameterSet* param,
                                        MatchContext* context) {
   UNREFERENCED_PARAMETER(context);
   unsigned long value_ulong = 0;
   if (param->Get(&value_ulong)) {
     unsigned long match_ulong = 0;
     opcode->GetArgument(0, &match_ulong);
     return (match_ulong != value_ulong)? EVAL_FALSE : EVAL_TRUE;
   } else {
     const void* value_ptr = NULL;
     if (param->Get(&value_ptr)) {
       const void* match_ptr = NULL;
       opcode->GetArgument(0, &match_ptr);
       return (match_ptr != value_ptr)? EVAL_FALSE : EVAL_TRUE;
     }
   }
   return EVAL_ERROR;
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpUlongMatchRange
 // Requires a unsigned long in selected_param.
 // Argument 0 is the stored lower bound to match.
 // Argument 1 is the stored upper bound to match.
 PolicyOpcode* OpcodeFactory::MakeOpUlongMatchRange(int16 selected_param,
                                                    unsigned long lower_bound,
                                                    unsigned long upper_bound,
                                                    uint32 options) {
   if (lower_bound > upper_bound) {
     return false;
   }
   PolicyOpcode* opcode = MakeBase(OP_ULONG_MATCH_RANGE, options,
                                   selected_param);
   if (NULL == opcode) return NULL;
   opcode->SetArgument(0, lower_bound);
   opcode->SetArgument(1, upper_bound);
   return opcode;
 }
 template <>
 EvalResult OpcodeEval<OP_ULONG_MATCH_RANGE>(PolicyOpcode* opcode,
                                             const ParameterSet* param,
                                             MatchContext* context) {
   UNREFERENCED_PARAMETER(context);
   unsigned long value = 0;
   if (!param->Get(&value)) return EVAL_ERROR;
   unsigned long lower_bound = 0;
   unsigned long upper_bound = 0;
   opcode->GetArgument(0, &lower_bound);
   opcode->GetArgument(1, &upper_bound);
   return((lower_bound <= value) && (upper_bound >= value))?
     EVAL_TRUE : EVAL_FALSE;
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpUlongAndMatch:
 // Requires a unsigned long in selected_param.
 // Argument 0 is the stored number to match.
 PolicyOpcode* OpcodeFactory::MakeOpUlongAndMatch(int16 selected_param,
                                                  unsigned long match,
                                                  uint32 options) {
   PolicyOpcode* opcode = MakeBase(OP_ULONG_AND_MATCH, options, selected_param);
   if (NULL == opcode) return NULL;
   opcode->SetArgument(0, match);
   return opcode;
 }
 template <>
 EvalResult OpcodeEval<OP_ULONG_AND_MATCH>(PolicyOpcode* opcode,
                                           const ParameterSet* param,
                                           MatchContext* context) {
   UNREFERENCED_PARAMETER(context);
   unsigned long value = 0;
   if (!param->Get(&value)) return EVAL_ERROR;
   unsigned long number = 0;
   opcode->GetArgument(0, &number);
   return (number & value)? EVAL_TRUE : EVAL_FALSE;
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode OpWStringMatch:
 // Requires a wchar_t* in selected_param.
 // Argument 0 is the byte displacement of the stored string.
 // Argument 1 is the lenght in chars of the stored string.
 // Argument 2 is the offset to apply on the input string. It has special values.
 // as noted in the header file.
 // Argument 3 is the string matching options.
 PolicyOpcode* OpcodeFactory::MakeOpWStringMatch(int16 selected_param,
                                                 const wchar_t* match_str,
                                                 int start_position,
                                                 StringMatchOptions match_opts,
                                                 uint32 options) {
   if (NULL == match_str) {
     return NULL;
   }
   if ('\0' == match_str[0]) {
     return NULL;
   }
   int lenght = lstrlenW(match_str);
   PolicyOpcode* opcode = MakeBase(OP_WSTRING_MATCH, options, selected_param);
   if (NULL == opcode) {
     return NULL;
   }
   ptrdiff_t delta_str = AllocRelative(opcode, match_str, wcslen(match_str)+1);
   if (0 == delta_str) {
     return NULL;
   }
   opcode->SetArgument(0, delta_str);
   opcode->SetArgument(1, lenght);
   opcode->SetArgument(2, start_position);
   opcode->SetArgument(3, match_opts);
   return opcode;
 }
 template<>
 EvalResult OpcodeEval<OP_WSTRING_MATCH>(PolicyOpcode* opcode,
                                         const ParameterSet* param,
                                         MatchContext* context) {
   if (NULL == context) {
     return EVAL_ERROR;
   }
   const wchar_t* source_str = NULL;
   if (!param->Get(&source_str)) return EVAL_ERROR;
   int start_position = 0;
   int match_len = 0;
   unsigned int match_opts = 0;
   opcode->GetArgument(1, &match_len);
   opcode->GetArgument(2, &start_position);
   opcode->GetArgument(3, &match_opts);
   const wchar_t* match_str = opcode->GetRelativeString(0);
   // Advance the source string to the last successfully evaluated position
   // according to the match context.
   source_str = &source_str[context->position];
   int source_len  = static_cast<int>(g_nt.wcslen(source_str));
   if (0 == source_len) {
     // If we reached the end of the source string there is nothing we can
     // match against.
     return EVAL_FALSE;
   }
   if (match_len > source_len) {
     // There can't be a positive match when the target string is bigger than
     // the source string
     return EVAL_FALSE;
   }
   BOOL case_sensitive = (match_opts & CASE_INSENSITIVE) ? TRUE : FALSE;
   // We have three cases, depending on the value of start_pos:
   // Case 1. We skip N characters and compare once.
   // Case 2: We skip to the end and compare once.
   // Case 3: We match the first substring (if we find any).
   if (start_position >= 0) {
     if (kSeekToEnd == start_position) {
         start_position = source_len - match_len;
     } else if (match_opts & EXACT_LENGHT) {
         // A sub-case of case 3 is when the EXACT_LENGHT flag is on
         // the match needs to be not just substring but full match.
         if ((match_len + start_position) != source_len) {
           return EVAL_FALSE;
         }
     }
     // Advance start_pos characters. Warning! this does not consider
     // utf16 encodings (surrogate pairs) or other Unicode 'features'.
     source_str += start_position;
     // Since we skipped, lets reevaluate just the lengths again.
     if ((match_len + start_position) > source_len) {
       return EVAL_FALSE;
     }
     UNICODE_STRING match_ustr;
     InitStringUnicode(match_str, match_len, &match_ustr);
     UNICODE_STRING source_ustr;
     InitStringUnicode(source_str, match_len, &source_ustr);
     if (0 == g_nt.RtlCompareUnicodeString(&match_ustr, &source_ustr,
                                           case_sensitive)) {
       // Match! update the match context.
       context->position += start_position + match_len;
       return EVAL_TRUE;
     } else {
       return EVAL_FALSE;
     }
   } else if (start_position < 0) {
     UNICODE_STRING match_ustr;
     InitStringUnicode(match_str, match_len, &match_ustr);
     UNICODE_STRING source_ustr;
     InitStringUnicode(source_str, match_len, &source_ustr);
     do {
       if (0 == g_nt.RtlCompareUnicodeString(&match_ustr, &source_ustr,
                                             case_sensitive)) {
         // Match! update the match context.
         context->position += (source_ustr.Buffer - source_str) + match_len;
         return EVAL_TRUE;
       }
       ++source_ustr.Buffer;
       --source_len;
     } while (source_len >= match_len);
   }
   return EVAL_FALSE;
 }
 //////////////////////////////////////////////////////////////////////////////
 // OpcodeMaker (other member functions).
 PolicyOpcode* OpcodeFactory::MakeBase(OpcodeID opcode_id,
                                       uint32 options,
                                       int16 selected_param) {
   if (memory_size() < sizeof(PolicyOpcode)) {
     return NULL;
   }
   // Create opcode using placement-new on the buffer memory.
   PolicyOpcode* opcode = new(memory_top_) PolicyOpcode();
   // Fill in the standard fields, that every opcode has.
   memory_top_ += sizeof(PolicyOpcode);
   opcode->opcode_id_ = opcode_id;
   opcode->options_ = static_cast<int16>(options);
   opcode->parameter_ = selected_param;
   return opcode;
 }
 ptrdiff_t OpcodeFactory::AllocRelative(void* start, const wchar_t* str,
                                        size_t lenght) {
   size_t bytes = lenght * sizeof(wchar_t);
   if (memory_size() < bytes) {
     return 0;
   }
   memory_bottom_ -= bytes;
   if (reinterpret_cast<UINT_PTR>(memory_bottom_) & 1) {
     // TODO(cpu) replace this for something better.
     ::DebugBreak();
   }
   memcpy(memory_bottom_, str, bytes);
   ptrdiff_t delta = memory_bottom_ - reinterpret_cast<char*>(start);
   return delta;
 }
 //////////////////////////////////////////////////////////////////////////////
 // Opcode evaluation dispatchers.
 // This function is the one and only entry for evaluating any opcode. It is
 // in charge of applying any relevant opcode options and calling EvaluateInner
 // were the actual dispatch-by-id is made. It would seem at first glance that
 // the dispatch should be done by virtual function (vtable) calls but you have
 // to remember that the opcodes are made in the broker process and copied as
 // raw memory to the target process.
 EvalResult PolicyOpcode::Evaluate(const ParameterSet* call_params,
                                   size_t param_count, MatchContext* match) {
   if (NULL == call_params) {
     return EVAL_ERROR;
   }
   const ParameterSet* selected_param = NULL;
   if (parameter_ >= 0) {
     if (static_cast<size_t>(parameter_) >= param_count) {
       return EVAL_ERROR;
     }
     selected_param = &call_params[parameter_];
   }
   EvalResult result = EvaluateHelper(selected_param, match);
   // Apply the general options regardless of the particular type of opcode.
   if (kPolNone == options_) {
     return result;
   }
   if (options_ & kPolNegateEval) {
     if (EVAL_TRUE == result) {
       result = EVAL_FALSE;
     } else if (EVAL_FALSE == result) {
       result = EVAL_TRUE;
     } else if (EVAL_ERROR != result) {
       result = EVAL_ERROR;
     }
   }
   if (NULL != match) {
     if (options_ & kPolClearContext) {
       match->Clear();
     }
     if (options_ & kPolUseOREval) {
       match->options = kPolUseOREval;
     }
   }
   return result;
 }
 #define OPCODE_EVAL(op, x, y, z) case op: return OpcodeEval<op>(x, y, z)
 EvalResult PolicyOpcode::EvaluateHelper(const ParameterSet* parameters,
                                        MatchContext* match) {
   switch (opcode_id_) {
     OPCODE_EVAL(OP_ALWAYS_FALSE, this, parameters, match);
     OPCODE_EVAL(OP_ALWAYS_TRUE, this, parameters, match);
     OPCODE_EVAL(OP_NUMBER_MATCH, this, parameters, match);
     OPCODE_EVAL(OP_ULONG_MATCH_RANGE, this, parameters, match);
     OPCODE_EVAL(OP_WSTRING_MATCH, this, parameters, match);
     OPCODE_EVAL(OP_ULONG_AND_MATCH, this, parameters, match);
     OPCODE_EVAL(OP_ACTION, this, parameters, match);
     default:
       return EVAL_ERROR;
   }
 }
 #undef OPCODE_EVAL
 }  // namespace sandbox

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security/sandbox/win/src/policy_engine_opcodes.cc@b8a032363ba2 (annotated)

security/sandbox/win/src/policy_engine_opcodes.cc