src/passes/SafeHeap.cpp - external/github.com/WebAssembly/binaryen - Git at Google

 /*
  * Copyright 2016 WebAssembly Community Group participants
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 //
 // Instruments code to check for incorrect heap access. This checks
 // for dereferencing 0 (null pointer access), reading past the valid
 // top of sbrk()-addressible memory, and incorrect alignment notation.
 //

 #include "wasm.h"
 #include "pass.h"
 #include "asm_v_wasm.h"
 #include "asmjs/shared-constants.h"
 #include "wasm-builder.h"
 #include "ast/bits.h"
 #include "ast/import-utils.h"

 namespace wasm {

 const Name DYNAMICTOP_PTR_IMPORT("DYNAMICTOP_PTR"),
            SEGFAULT_IMPORT("segfault"),
            ALIGNFAULT_IMPORT("alignfault");

 static Name getLoadName(Load* curr) {
   std::string ret = "SAFE_HEAP_LOAD_";
   ret += printWasmType(curr->type);
   ret += "_" + std::to_string(curr->bytes) + "_";
   if (!isWasmTypeFloat(curr->type) && !curr->signed_) {
     ret += "U_";
   }
   if (curr->isAtomic) {
     ret += "A";
   } else {
     ret += std::to_string(curr->align);
   }
   return ret;
 }

 static Name getStoreName(Store* curr) {
   std::string ret = "SAFE_HEAP_STORE_";
   ret += printWasmType(curr->valueType);
   ret += "_" + std::to_string(curr->bytes) + "_";
   if (curr->isAtomic) {
     ret += "A";
   } else {
     ret += std::to_string(curr->align);
   }
   return ret;
 }

 struct AccessInstrumenter : public WalkerPass<PostWalker<AccessInstrumenter>> {
   bool isFunctionParallel() override { return true; }

   AccessInstrumenter* create() override { return new AccessInstrumenter; }

   void visitLoad(Load* curr) {
     if (curr->type == unreachable) return;
     Builder builder(*getModule());
     replaceCurrent(
       builder.makeCall(
         getLoadName(curr),
         {
           curr->ptr,
           builder.makeConst(Literal(int32_t(curr->offset))),
         },
         curr->type
       )
     );
   }

   void visitStore(Store* curr) {
     if (curr->type == unreachable) return;
     Builder builder(*getModule());
     replaceCurrent(
       builder.makeCall(
         getStoreName(curr),
         {
           curr->ptr,
           builder.makeConst(Literal(int32_t(curr->offset))),
           curr->value,
         },
         none
       )
     );
   }
 };

 struct SafeHeap : public Pass {
   void run(PassRunner* runner, Module* module) override {
     // add imports
     addImports(module);
     // instrument loads and stores
     PassRunner instrumenter(module);
     instrumenter.setIsNested(true);
     instrumenter.add<AccessInstrumenter>();
     instrumenter.run();
     // add helper checking funcs and imports
     addGlobals(module);
   }

   Name dynamicTopPtr, segfault, alignfault;

   void addImports(Module* module) {
     // imports
     if (auto* existing = ImportUtils::getImport(*module, ENV, DYNAMICTOP_PTR_IMPORT)) {
       dynamicTopPtr = existing->name;
     } else {
       auto* import = new Import;
       import->name = dynamicTopPtr = DYNAMICTOP_PTR_IMPORT;
       import->module = ENV;
       import->base = DYNAMICTOP_PTR_IMPORT;
       import->kind = ExternalKind::Global;
       import->globalType = i32;
       module->addImport(import);
     }
     if (auto* existing = ImportUtils::getImport(*module, ENV, SEGFAULT_IMPORT)) {
       dynamicTopPtr = existing->name;
     } else {
       auto* import = new Import;
       import->name = segfault = SEGFAULT_IMPORT;
       import->module = ENV;
       import->base = SEGFAULT_IMPORT;
       import->kind = ExternalKind::Function;
       import->functionType = ensureFunctionType("v", module)->name;
       module->addImport(import);
     }
     if (auto* existing = ImportUtils::getImport(*module, ENV, ALIGNFAULT_IMPORT)) {
       dynamicTopPtr = existing->name;
     } else {
       auto* import = new Import;
       import->name = alignfault = ALIGNFAULT_IMPORT;
       import->module = ENV;
       import->base = ALIGNFAULT_IMPORT;
       import->kind = ExternalKind::Function;
       import->functionType = ensureFunctionType("v", module)->name;
       module->addImport(import);
     }
   }

   void addGlobals(Module* module) {
     // load funcs
     Load load;
     for (auto type : { i32, i64, f32, f64 }) {
       load.type = type;
       for (Index bytes : { 1, 2, 4, 8 }) {
         load.bytes = bytes;
         if (bytes > getWasmTypeSize(type)) continue;
         for (auto signed_ : { true, false }) {
           load.signed_ = signed_;
           if (isWasmTypeFloat(type) && signed_) continue;
           for (Index align : { 1, 2, 4, 8 }) {
             load.align = align;
             if (align > bytes) continue;
             for (auto isAtomic : { true, false }) {
               load.isAtomic = isAtomic;
               if (isAtomic && align != bytes) continue;
               if (isAtomic && !module->memory.shared) continue;
               addLoadFunc(load, module);
             }
           }
         }
       }
     }
     // store funcs
     Store store;
     for (auto valueType : { i32, i64, f32, f64 }) {
       store.valueType = valueType;
       store.type = none;
       for (Index bytes : { 1, 2, 4, 8 }) {
         store.bytes = bytes;
         if (bytes > getWasmTypeSize(valueType)) continue;
         for (Index align : { 1, 2, 4, 8 }) {
           store.align = align;
           if (align > bytes) continue;
           for (auto isAtomic : { true, false }) {
             store.isAtomic = isAtomic;
             if (isAtomic && align != bytes) continue;
             if (isAtomic && !module->memory.shared) continue;
             addStoreFunc(store, module);
           }
         }
       }
     }
   }

   // creates a function for a particular style of load
   void addLoadFunc(Load style, Module* module) {
     auto* func = new Function;
     func->name = getLoadName(&style);
     func->params.push_back(i32); // pointer
     func->params.push_back(i32); // offset
     func->vars.push_back(i32); // pointer + offset
     func->result = style.type;
     Builder builder(*module);
     auto* block = builder.makeBlock();
     block->list.push_back(
       builder.makeSetLocal(
         2,
         builder.makeBinary(
           AddInt32,
           builder.makeGetLocal(0, i32),
           builder.makeGetLocal(1, i32)
         )
       )
     );
     // check for reading past valid memory: if pointer + offset + bytes
     block->list.push_back(
       makeBoundsCheck(style.type, builder, 2)
     );
     // check proper alignment
     if (style.align > 1) {
       block->list.push_back(
         makeAlignCheck(style.align, builder, 2)
       );
     }
     // do the load
     auto* load = module->allocator.alloc<Load>();
     *load = style; // basically the same as the template we are given!
     load->ptr = builder.makeGetLocal(2, i32);
     Expression* last = load;
     if (load->isAtomic && load->signed_) {
       // atomic loads cannot be signed, manually sign it
       last = Bits::makeSignExt(load, load->bytes, *module);
       load->signed_ = false;
     }
     block->list.push_back(last);
     block->finalize(style.type);
     func->body = block;
     module->addFunction(func);
   }

   // creates a function for a particular type of store
   void addStoreFunc(Store style, Module* module) {
     auto* func = new Function;
     func->name = getStoreName(&style);
     func->params.push_back(i32); // pointer
     func->params.push_back(i32); // offset
     func->params.push_back(style.valueType); // value
     func->vars.push_back(i32); // pointer + offset
     func->result = none;
     Builder builder(*module);
     auto* block = builder.makeBlock();
     block->list.push_back(
       builder.makeSetLocal(
         3,
         builder.makeBinary(
           AddInt32,
           builder.makeGetLocal(0, i32),
           builder.makeGetLocal(1, i32)
         )
       )
     );
     // check for reading past valid memory: if pointer + offset + bytes
     block->list.push_back(
       makeBoundsCheck(style.valueType, builder, 3)
     );
     // check proper alignment
     if (style.align > 1) {
       block->list.push_back(
         makeAlignCheck(style.align, builder, 3)
       );
     }
     // do the store
     auto* store = module->allocator.alloc<Store>();
     *store = style; // basically the same as the template we are given!
     store->ptr = builder.makeGetLocal(3, i32);
     store->value = builder.makeGetLocal(2, style.valueType);
     block->list.push_back(store);
     block->finalize(none);
     func->body = block;
     module->addFunction(func);
   }

   Expression* makeAlignCheck(Address align, Builder& builder, Index local) {
     return builder.makeIf(
       builder.makeBinary(
         AndInt32,
         builder.makeGetLocal(local, i32),
         builder.makeConst(Literal(int32_t(align - 1)))
       ),
       builder.makeCallImport(alignfault, {}, none)
     );
   }

   Expression* makeBoundsCheck(WasmType type, Builder& builder, Index local) {
     return builder.makeIf(
       builder.makeBinary(
         OrInt32,
         builder.makeBinary(
           EqInt32,
           builder.makeGetLocal(local, i32),
           builder.makeConst(Literal(int32_t(0)))
         ),
         builder.makeBinary(
           GtUInt32,
           builder.makeBinary(
             AddInt32,
             builder.makeGetLocal(local, i32),
             builder.makeConst(Literal(int32_t(getWasmTypeSize(type))))
           ),
           builder.makeLoad(4, false, 0, 4,
             builder.makeGetGlobal(dynamicTopPtr, i32), i32
           )
         )
       ),
       builder.makeCallImport(segfault, {}, none)
     );
   }
 };

 Pass *createSafeHeapPass() {
   return new SafeHeap();
 }

 } // namespace wasm
	/*
	* Copyright 2016 WebAssembly Community Group participants
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	//
	// Instruments code to check for incorrect heap access. This checks
	// for dereferencing 0 (null pointer access), reading past the valid
	// top of sbrk()-addressible memory, and incorrect alignment notation.
	//

	#include "wasm.h"
	#include "pass.h"
	#include "asm_v_wasm.h"
	#include "asmjs/shared-constants.h"
	#include "wasm-builder.h"
	#include "ast/bits.h"
	#include "ast/import-utils.h"

	namespace wasm {

	const Name DYNAMICTOP_PTR_IMPORT("DYNAMICTOP_PTR"),
	SEGFAULT_IMPORT("segfault"),
	ALIGNFAULT_IMPORT("alignfault");

	static Name getLoadName(Load* curr) {
	std::string ret = "SAFE_HEAP_LOAD_";
	ret += printWasmType(curr->type);
	ret += "_" + std::to_string(curr->bytes) + "_";
	if (!isWasmTypeFloat(curr->type) && !curr->signed_) {
	ret += "U_";
	}
	if (curr->isAtomic) {
	ret += "A";
	} else {
	ret += std::to_string(curr->align);
	}
	return ret;
	}

	static Name getStoreName(Store* curr) {
	std::string ret = "SAFE_HEAP_STORE_";
	ret += printWasmType(curr->valueType);
	ret += "_" + std::to_string(curr->bytes) + "_";
	if (curr->isAtomic) {
	ret += "A";
	} else {
	ret += std::to_string(curr->align);
	}
	return ret;
	}

	struct AccessInstrumenter : public WalkerPass<PostWalker<AccessInstrumenter>> {
	bool isFunctionParallel() override { return true; }

	AccessInstrumenter* create() override { return new AccessInstrumenter; }

	void visitLoad(Load* curr) {
	if (curr->type == unreachable) return;
	Builder builder(*getModule());
	replaceCurrent(
	builder.makeCall(
	getLoadName(curr),
	{
	curr->ptr,
	builder.makeConst(Literal(int32_t(curr->offset))),
	},
	curr->type
	)
	);
	}

	void visitStore(Store* curr) {
	if (curr->type == unreachable) return;
	Builder builder(*getModule());
	replaceCurrent(
	builder.makeCall(
	getStoreName(curr),
	{
	curr->ptr,
	builder.makeConst(Literal(int32_t(curr->offset))),
	curr->value,
	},
	none
	)
	);
	}
	};

	struct SafeHeap : public Pass {
	void run(PassRunner* runner, Module* module) override {
	// add imports
	addImports(module);
	// instrument loads and stores
	PassRunner instrumenter(module);
	instrumenter.setIsNested(true);
	instrumenter.add<AccessInstrumenter>();
	instrumenter.run();
	// add helper checking funcs and imports
	addGlobals(module);
	}

	Name dynamicTopPtr, segfault, alignfault;

	void addImports(Module* module) {
	// imports
	if (auto* existing = ImportUtils::getImport(*module, ENV, DYNAMICTOP_PTR_IMPORT)) {
	dynamicTopPtr = existing->name;
	} else {
	auto* import = new Import;
	import->name = dynamicTopPtr = DYNAMICTOP_PTR_IMPORT;
	import->module = ENV;
	import->base = DYNAMICTOP_PTR_IMPORT;
	import->kind = ExternalKind::Global;
	import->globalType = i32;
	module->addImport(import);
	}
	if (auto* existing = ImportUtils::getImport(*module, ENV, SEGFAULT_IMPORT)) {
	dynamicTopPtr = existing->name;
	} else {
	auto* import = new Import;
	import->name = segfault = SEGFAULT_IMPORT;
	import->module = ENV;
	import->base = SEGFAULT_IMPORT;
	import->kind = ExternalKind::Function;
	import->functionType = ensureFunctionType("v", module)->name;
	module->addImport(import);
	}
	if (auto* existing = ImportUtils::getImport(*module, ENV, ALIGNFAULT_IMPORT)) {
	dynamicTopPtr = existing->name;
	} else {
	auto* import = new Import;
	import->name = alignfault = ALIGNFAULT_IMPORT;
	import->module = ENV;
	import->base = ALIGNFAULT_IMPORT;
	import->kind = ExternalKind::Function;
	import->functionType = ensureFunctionType("v", module)->name;
	module->addImport(import);
	}
	}

	void addGlobals(Module* module) {
	// load funcs
	Load load;
	for (auto type : { i32, i64, f32, f64 }) {
	load.type = type;
	for (Index bytes : { 1, 2, 4, 8 }) {
	load.bytes = bytes;
	if (bytes > getWasmTypeSize(type)) continue;
	for (auto signed_ : { true, false }) {
	load.signed_ = signed_;
	if (isWasmTypeFloat(type) && signed_) continue;
	for (Index align : { 1, 2, 4, 8 }) {
	load.align = align;
	if (align > bytes) continue;
	for (auto isAtomic : { true, false }) {
	load.isAtomic = isAtomic;
	if (isAtomic && align != bytes) continue;
	if (isAtomic && !module->memory.shared) continue;
	addLoadFunc(load, module);
	}
	}
	}
	}
	}
	// store funcs
	Store store;
	for (auto valueType : { i32, i64, f32, f64 }) {
	store.valueType = valueType;
	store.type = none;
	for (Index bytes : { 1, 2, 4, 8 }) {
	store.bytes = bytes;
	if (bytes > getWasmTypeSize(valueType)) continue;
	for (Index align : { 1, 2, 4, 8 }) {
	store.align = align;
	if (align > bytes) continue;
	for (auto isAtomic : { true, false }) {
	store.isAtomic = isAtomic;
	if (isAtomic && align != bytes) continue;
	if (isAtomic && !module->memory.shared) continue;
	addStoreFunc(store, module);
	}
	}
	}
	}
	}

	// creates a function for a particular style of load
	void addLoadFunc(Load style, Module* module) {
	auto* func = new Function;
	func->name = getLoadName(&style);
	func->params.push_back(i32); // pointer
	func->params.push_back(i32); // offset
	func->vars.push_back(i32); // pointer + offset
	func->result = style.type;
	Builder builder(*module);
	auto* block = builder.makeBlock();
	block->list.push_back(
	builder.makeSetLocal(
	2,
	builder.makeBinary(
	AddInt32,
	builder.makeGetLocal(0, i32),
	builder.makeGetLocal(1, i32)
	)
	)
	);
	// check for reading past valid memory: if pointer + offset + bytes
	block->list.push_back(
	makeBoundsCheck(style.type, builder, 2)
	);
	// check proper alignment
	if (style.align > 1) {
	block->list.push_back(
	makeAlignCheck(style.align, builder, 2)
	);
	}
	// do the load
	auto* load = module->allocator.alloc<Load>();
	*load = style; // basically the same as the template we are given!
	load->ptr = builder.makeGetLocal(2, i32);
	Expression* last = load;
	if (load->isAtomic && load->signed_) {
	// atomic loads cannot be signed, manually sign it
	last = Bits::makeSignExt(load, load->bytes, *module);
	load->signed_ = false;
	}
	block->list.push_back(last);
	block->finalize(style.type);
	func->body = block;
	module->addFunction(func);
	}

	// creates a function for a particular type of store
	void addStoreFunc(Store style, Module* module) {
	auto* func = new Function;
	func->name = getStoreName(&style);
	func->params.push_back(i32); // pointer
	func->params.push_back(i32); // offset
	func->params.push_back(style.valueType); // value
	func->vars.push_back(i32); // pointer + offset
	func->result = none;
	Builder builder(*module);
	auto* block = builder.makeBlock();
	block->list.push_back(
	builder.makeSetLocal(
	3,
	builder.makeBinary(
	AddInt32,
	builder.makeGetLocal(0, i32),
	builder.makeGetLocal(1, i32)
	)
	)
	);
	// check for reading past valid memory: if pointer + offset + bytes
	block->list.push_back(
	makeBoundsCheck(style.valueType, builder, 3)
	);
	// check proper alignment
	if (style.align > 1) {
	block->list.push_back(
	makeAlignCheck(style.align, builder, 3)
	);
	}
	// do the store
	auto* store = module->allocator.alloc<Store>();
	*store = style; // basically the same as the template we are given!
	store->ptr = builder.makeGetLocal(3, i32);
	store->value = builder.makeGetLocal(2, style.valueType);
	block->list.push_back(store);
	block->finalize(none);
	func->body = block;
	module->addFunction(func);
	}

	Expression* makeAlignCheck(Address align, Builder& builder, Index local) {
	return builder.makeIf(
	builder.makeBinary(
	AndInt32,
	builder.makeGetLocal(local, i32),
	builder.makeConst(Literal(int32_t(align - 1)))
	),
	builder.makeCallImport(alignfault, {}, none)
	);
	}

	Expression* makeBoundsCheck(WasmType type, Builder& builder, Index local) {
	return builder.makeIf(
	builder.makeBinary(
	OrInt32,
	builder.makeBinary(
	EqInt32,
	builder.makeGetLocal(local, i32),
	builder.makeConst(Literal(int32_t(0)))
	),
	builder.makeBinary(
	GtUInt32,
	builder.makeBinary(
	AddInt32,
	builder.makeGetLocal(local, i32),
	builder.makeConst(Literal(int32_t(getWasmTypeSize(type))))
	),
	builder.makeLoad(4, false, 0, 4,
	builder.makeGetGlobal(dynamicTopPtr, i32), i32
	)
	)
	),
	builder.makeCallImport(segfault, {}, none)
	);
	}
	};

	Pass *createSafeHeapPass() {
	return new SafeHeap();
	}

	} // namespace wasm