375 lines
10 KiB
Go
375 lines
10 KiB
Go
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// Copyright 2017 The go-interpreter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// package validate provides functions for validating WebAssembly modules.
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package validate
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import (
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"bytes"
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"io"
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"github.com/go-interpreter/wagon/wasm"
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ops "github.com/go-interpreter/wagon/wasm/operators"
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)
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// vibhavp: TODO: We do not verify whether blocks don't access for the parent block, do that.
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func verifyBody(fn *wasm.FunctionSig, body *wasm.FunctionBody, module *wasm.Module) (*mockVM, error) {
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vm := &mockVM{
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stack: []operand{},
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stackTop: 0,
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code: bytes.NewReader(body.Code),
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origLength: len(body.Code),
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polymorphic: false,
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blocks: []block{},
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curFunc: fn,
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}
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localVariables := []operand{}
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// Paramters count as local variables too
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// This comment explains how local variables work: https://github.com/WebAssembly/design/issues/1037#issuecomment-293505798
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for _, entry := range fn.ParamTypes {
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localVariables = append(localVariables, operand{entry})
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}
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for _, entry := range body.Locals {
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vars := make([]operand, entry.Count)
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for i := uint32(0); i < entry.Count; i++ {
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vars[i].Type = entry.Type
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logger.Printf("Var %v", entry.Type)
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}
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localVariables = append(localVariables, vars...)
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}
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for {
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op, err := vm.code.ReadByte()
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if err == io.EOF {
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break
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} else if err != nil {
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return vm, err
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}
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opStruct, err := ops.New(op)
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if err != nil {
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return vm, err
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}
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logger.Printf("PC: %d OP: %s polymorphic: %v", vm.pc(), opStruct.Name, vm.isPolymorphic())
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if !opStruct.Polymorphic {
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if err := vm.adjustStack(opStruct); err != nil {
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return vm, err
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}
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}
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switch op {
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case ops.If, ops.Block, ops.Loop:
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sig, err := vm.fetchVarInt()
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if err != nil {
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return vm, err
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}
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switch wasm.ValueType(sig) {
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case wasm.ValueTypeI32, wasm.ValueTypeI64, wasm.ValueTypeF32, wasm.ValueTypeF64, wasm.ValueType(wasm.BlockTypeEmpty):
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vm.pushBlock(op, wasm.BlockType(sig))
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default:
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if !vm.isPolymorphic() {
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return vm, InvalidImmediateError{"block_type", opStruct.Name}
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}
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}
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case ops.Else:
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block := vm.topBlock()
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if block == nil || block.op != ops.If {
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return vm, UnmatchedOpError(op)
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}
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if block.blockType != wasm.BlockTypeEmpty {
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top, under := vm.topOperand()
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if !vm.isPolymorphic() && (under || top.Type != wasm.ValueType(block.blockType)) {
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return vm, InvalidTypeError{wasm.ValueType(block.blockType), top.Type}
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}
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vm.pushOperand(wasm.ValueType(block.blockType))
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}
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vm.stackTop = block.stackTop
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case ops.End:
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isPolymorphic := vm.isPolymorphic()
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block := vm.popBlock()
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if block == nil {
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return vm, UnmatchedOpError(op)
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}
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if block.blockType != wasm.BlockTypeEmpty {
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top, under := vm.topOperand()
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if !isPolymorphic && (under || top.Type != wasm.ValueType(block.blockType)) {
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return vm, InvalidTypeError{wasm.ValueType(block.blockType), top.Type}
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}
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vm.stackTop = block.stackTop
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vm.pushOperand(wasm.ValueType(block.blockType))
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vm.stackTop = block.stackTop + 1 // as we pushed an element
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} else {
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vm.stackTop = block.stackTop
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}
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case ops.BrIf, ops.Br:
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depth, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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if err = vm.canBranch(int(depth)); !vm.isPolymorphic() && err != nil {
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return vm, err
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}
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if op == ops.Br {
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vm.setPolymorphic()
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}
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case ops.BrTable:
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operand, under := vm.popOperand()
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if !vm.isPolymorphic() && (under || operand.Type != wasm.ValueTypeI32) {
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return vm, InvalidTypeError{wasm.ValueTypeI32, operand.Type}
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}
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// read table entries
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targetCount, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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var targetTable []uint32
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for i := uint32(0); i < targetCount; i++ {
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entry, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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if err = vm.canBranch(int(entry)); !vm.isPolymorphic() && err != nil {
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return vm, err
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}
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targetTable = append(targetTable, entry)
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}
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defaultTarget, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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if err = vm.canBranch(int(defaultTarget)); !vm.isPolymorphic() && err != nil {
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return vm, err
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}
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vm.setPolymorphic()
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case ops.Return:
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if len(fn.ReturnTypes) > 1 {
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panic("not implemented")
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}
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if len(fn.ReturnTypes) != 0 {
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// only single returns supported for now
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top, under := vm.popOperand()
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if !vm.isPolymorphic() && (under || top.Type != fn.ReturnTypes[0]) {
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return vm, InvalidTypeError{fn.ReturnTypes[0], top.Type}
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}
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}
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vm.setPolymorphic()
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case ops.Unreachable:
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vm.setPolymorphic()
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case ops.I32Const:
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_, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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case ops.I64Const:
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_, err := vm.fetchVarInt64()
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if err != nil {
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return vm, err
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}
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case ops.F32Const:
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_, err := vm.fetchUint32()
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if err != nil {
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return vm, err
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}
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case ops.F64Const:
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_, err := vm.fetchUint64()
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if err != nil {
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return vm, err
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}
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case ops.GetLocal, ops.SetLocal, ops.TeeLocal:
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i, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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if int(i) >= len(localVariables) {
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return vm, InvalidLocalIndexError(i)
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}
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v := localVariables[i]
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if op == ops.GetLocal {
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vm.pushOperand(v.Type)
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} else { // == set_local or tee_local
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top, under := vm.popOperand()
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if !vm.isPolymorphic() && (under || top.Type != v.Type) {
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return vm, InvalidTypeError{v.Type, top.Type}
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}
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if op == ops.TeeLocal {
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vm.pushOperand(v.Type)
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}
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}
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case ops.GetGlobal, ops.SetGlobal:
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index, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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gv := module.GetGlobal(int(index))
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if gv == nil {
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return vm, wasm.InvalidGlobalIndexError(index)
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}
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if op == ops.GetGlobal {
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vm.pushOperand(gv.Type.Type)
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} else {
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val, under := vm.popOperand()
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if !vm.isPolymorphic() && (under || val.Type != gv.Type.Type) {
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return vm, InvalidTypeError{gv.Type.Type, val.Type}
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}
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}
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case ops.I32Load, ops.I64Load, ops.F32Load, ops.F64Load, ops.I32Load8s, ops.I32Load8u, ops.I32Load16s, ops.I32Load16u, ops.I64Load8s, ops.I64Load8u, ops.I64Load16s, ops.I64Load16u, ops.I64Load32s, ops.I64Load32u, ops.I32Store, ops.I64Store, ops.F32Store, ops.F64Store, ops.I32Store8, ops.I32Store16, ops.I64Store8, ops.I64Store16, ops.I64Store32:
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// read memory_immediate
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// flags
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_, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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// offset
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_, err = vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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case ops.CurrentMemory, ops.GrowMemory:
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_, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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case ops.Call:
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index, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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fn := module.GetFunction(int(index))
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if fn == nil {
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return vm, wasm.InvalidFunctionIndexError(index)
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}
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logger.Printf("Function being called: %v", fn)
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for index := range fn.Sig.ParamTypes {
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argType := fn.Sig.ParamTypes[len(fn.Sig.ParamTypes)-index-1]
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operand, under := vm.popOperand()
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if !vm.isPolymorphic() && (under || operand.Type != argType) {
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return vm, InvalidTypeError{argType, operand.Type}
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}
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}
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if len(fn.Sig.ReturnTypes) > 0 {
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vm.pushOperand(fn.Sig.ReturnTypes[0])
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}
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case ops.CallIndirect:
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if module.Table == nil || len(module.Table.Entries) == 0 {
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return vm, NoSectionError(wasm.SectionIDTable)
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}
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// The call_indirect process consists of getting two i32 values
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// off (first from the bytecode stream, and the second from
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// the stack) and using first as an index into the "Types" section
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// of the module, while the the second one into the function index
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// space. The signature of the two elements are then compared
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// to see if they match, and the call proceeds as normal if they
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// do.
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// Since this is possible only during program execution, we only
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// perform the static check for the function index mentioned
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// in the bytecode stream here.
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// type index
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index, err := vm.fetchVarUint()
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if err != nil {
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return vm, err
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}
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fnExpectSig := module.Types.Entries[index]
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if operand, under := vm.popOperand(); !vm.isPolymorphic() && (under || operand.Type != wasm.ValueTypeI32) {
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return vm, InvalidTypeError{wasm.ValueTypeI32, operand.Type}
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}
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for index := range fnExpectSig.ParamTypes {
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argType := fnExpectSig.ParamTypes[len(fnExpectSig.ParamTypes)-index-1]
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operand, under := vm.popOperand()
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if !vm.isPolymorphic() && (under || (operand.Type != argType)) {
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return vm, InvalidTypeError{argType, operand.Type}
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}
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}
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if len(fnExpectSig.ReturnTypes) > 0 {
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vm.pushOperand(fnExpectSig.ReturnTypes[0])
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}
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case ops.Drop:
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if _, under := vm.popOperand(); !vm.isPolymorphic() && under {
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return vm, ErrStackUnderflow
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}
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case ops.Select:
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if vm.isPolymorphic() {
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continue
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}
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operands := make([]operand, 2)
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c, under := vm.popOperand()
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if under || c.Type != wasm.ValueTypeI32 {
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return vm, InvalidTypeError{wasm.ValueTypeI32, c.Type}
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}
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for i := 0; i < 2; i++ {
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operand, under := vm.popOperand()
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if !vm.isPolymorphic() && under {
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return vm, ErrStackUnderflow
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}
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operands[i] = operand
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}
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// last 2 popped values should be of the same type
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if operands[0].Type != operands[1].Type {
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return vm, InvalidTypeError{operands[1].Type, operands[2].Type}
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}
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vm.pushOperand(operands[1].Type)
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}
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}
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return vm, nil
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}
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// VerifyModule verifies the given module according to WebAssembly verification
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// specs.
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func VerifyModule(module *wasm.Module) error {
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if module.Function == nil || module.Types == nil || len(module.Types.Entries) == 0 {
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return nil
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}
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if module.Code == nil {
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return NoSectionError(wasm.SectionIDCode)
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}
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logger.Printf("There are %d functions", len(module.Function.Types))
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for i, fn := range module.FunctionIndexSpace {
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if vm, err := verifyBody(fn.Sig, fn.Body, module); err != nil {
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return Error{vm.pc(), i, err}
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}
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logger.Printf("No errors in function %d", i)
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}
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return nil
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}
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