wasmi/src/validation/mod.rs

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use std::error;
use std::fmt;
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use std::collections::HashSet;
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use parity_wasm::elements::{
BlockType, External, GlobalEntry, GlobalType, Internal, MemoryType, Module, Opcode,
ResizableLimits, TableType, ValueType, InitExpr, Type
};
use common::stack;
use self::context::ModuleContextBuilder;
use self::func::Validator;
use memory_units::Pages;
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use isa;
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mod context;
mod func;
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mod util;
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#[cfg(test)]
mod tests;
#[derive(Debug)]
pub struct Error(String);
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.0)
}
}
impl error::Error for Error {
fn description(&self) -> &str {
&self.0
}
}
impl From<stack::Error> for Error {
fn from(e: stack::Error) -> Error {
Error(format!("Stack: {}", e))
}
}
#[derive(Clone)]
pub struct ValidatedModule {
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pub code_map: Vec<isa::Instructions>,
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pub module: Module,
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}
impl ::std::ops::Deref for ValidatedModule {
type Target = Module;
fn deref(&self) -> &Module {
&self.module
}
}
pub fn deny_floating_point(module: &Module) -> Result<(), Error> {
if let Some(code) = module.code_section() {
for op in code.bodies().iter().flat_map(|body| body.code().elements()) {
use parity_wasm::elements::Opcode::*;
macro_rules! match_eq {
($pattern:pat) => {
|val| if let $pattern = *val { true } else { false }
};
}
const DENIED: &[fn(&Opcode) -> bool] = &[
match_eq!(F32Load(_, _)),
match_eq!(F64Load(_, _)),
match_eq!(F32Store(_, _)),
match_eq!(F64Store(_, _)),
match_eq!(F32Const(_)),
match_eq!(F64Const(_)),
match_eq!(F32Eq),
match_eq!(F32Ne),
match_eq!(F32Lt),
match_eq!(F32Gt),
match_eq!(F32Le),
match_eq!(F32Ge),
match_eq!(F64Eq),
match_eq!(F64Ne),
match_eq!(F64Lt),
match_eq!(F64Gt),
match_eq!(F64Le),
match_eq!(F64Ge),
match_eq!(F32Abs),
match_eq!(F32Neg),
match_eq!(F32Ceil),
match_eq!(F32Floor),
match_eq!(F32Trunc),
match_eq!(F32Nearest),
match_eq!(F32Sqrt),
match_eq!(F32Add),
match_eq!(F32Sub),
match_eq!(F32Mul),
match_eq!(F32Div),
match_eq!(F32Min),
match_eq!(F32Max),
match_eq!(F32Copysign),
match_eq!(F64Abs),
match_eq!(F64Neg),
match_eq!(F64Ceil),
match_eq!(F64Floor),
match_eq!(F64Trunc),
match_eq!(F64Nearest),
match_eq!(F64Sqrt),
match_eq!(F64Add),
match_eq!(F64Sub),
match_eq!(F64Mul),
match_eq!(F64Div),
match_eq!(F64Min),
match_eq!(F64Max),
match_eq!(F64Copysign),
match_eq!(F32ConvertSI32),
match_eq!(F32ConvertUI32),
match_eq!(F32ConvertSI64),
match_eq!(F32ConvertUI64),
match_eq!(F32DemoteF64),
match_eq!(F64ConvertSI32),
match_eq!(F64ConvertUI32),
match_eq!(F64ConvertSI64),
match_eq!(F64ConvertUI64),
match_eq!(F64PromoteF32),
match_eq!(F32ReinterpretI32),
match_eq!(F64ReinterpretI64),
match_eq!(I32TruncSF32),
match_eq!(I32TruncUF32),
match_eq!(I32TruncSF64),
match_eq!(I32TruncUF64),
match_eq!(I64TruncSF32),
match_eq!(I64TruncUF32),
match_eq!(I64TruncSF64),
match_eq!(I64TruncUF64),
match_eq!(I32ReinterpretF32),
match_eq!(I64ReinterpretF64),
];
if DENIED.iter().any(|is_denied| is_denied(op)) {
return Err(Error(format!("Floating point operation denied: {:?}", op)));
}
}
}
if let (Some(sec), Some(types)) = (module.function_section(), module.type_section()) {
use parity_wasm::elements::{Type, ValueType};
let types = types.types();
for sig in sec.entries() {
if let Some(typ) = types.get(sig.type_ref() as usize) {
match *typ {
Type::Function(ref func) => {
if func.params()
.iter()
.chain(func.return_type().as_ref())
.any(|&typ| typ == ValueType::F32 || typ == ValueType::F64)
{
return Err(Error(format!("Use of floating point types denied")));
}
}
}
}
}
}
Ok(())
}
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pub fn validate_module(module: Module) -> Result<ValidatedModule, Error> {
let mut context_builder = ModuleContextBuilder::new();
let mut imported_globals = Vec::new();
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let mut code_map = Vec::new();
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// Copy types from module as is.
context_builder.set_types(
module
.type_section()
.map(|ts| {
ts.types()
.into_iter()
.map(|&Type::Function(ref ty)| ty)
.cloned()
.collect()
})
.unwrap_or_default(),
);
// Fill elements with imported values.
for import_entry in module
.import_section()
.map(|i| i.entries())
.unwrap_or_default()
{
match *import_entry.external() {
External::Function(idx) => context_builder.push_func_type_index(idx),
External::Table(ref table) => context_builder.push_table(table.clone()),
External::Memory(ref memory) => context_builder.push_memory(memory.clone()),
External::Global(ref global) => {
context_builder.push_global(global.clone());
imported_globals.push(global.clone());
}
}
}
// Concatenate elements with defined in the module.
if let Some(function_section) = module.function_section() {
for func_entry in function_section.entries() {
context_builder.push_func_type_index(func_entry.type_ref())
}
}
if let Some(table_section) = module.table_section() {
for table_entry in table_section.entries() {
validate_table_type(table_entry)?;
context_builder.push_table(table_entry.clone());
}
}
if let Some(mem_section) = module.memory_section() {
for mem_entry in mem_section.entries() {
validate_memory_type(mem_entry)?;
context_builder.push_memory(mem_entry.clone());
}
}
if let Some(global_section) = module.global_section() {
for global_entry in global_section.entries() {
validate_global_entry(global_entry, &imported_globals)?;
context_builder.push_global(global_entry.global_type().clone());
}
}
let context = context_builder.build();
let function_section_len = module
.function_section()
.map(|s| s.entries().len())
.unwrap_or(0);
let code_section_len = module.code_section().map(|s| s.bodies().len()).unwrap_or(0);
if function_section_len != code_section_len {
return Err(Error(format!(
"length of function section is {}, while len of code section is {}",
function_section_len,
code_section_len
)));
}
// validate every function body in user modules
if function_section_len != 0 {
// tests use invalid code
let function_section = module.function_section().expect(
"function_section_len != 0; qed",
);
let code_section = module.code_section().expect(
"function_section_len != 0; function_section_len == code_section_len; qed",
);
// check every function body
for (index, function) in function_section.entries().iter().enumerate() {
let function_body = code_section.bodies().get(index as usize).ok_or(
Error(format!(
"Missing body for function {}",
index
)),
)?;
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let code = Validator::validate_function(&context, function, function_body)
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.map_err(|e| {
let Error(ref msg) = e;
Error(format!("Function #{} validation error: {}", index, msg))
})?;
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code_map.push(code);
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}
}
// validate start section
if let Some(start_fn_idx) = module.start_section() {
let (params, return_ty) = context.require_function(start_fn_idx)?;
if return_ty != BlockType::NoResult || params.len() != 0 {
return Err(Error(
"start function expected to have type [] -> []".into(),
));
}
}
// validate export section
if let Some(export_section) = module.export_section() {
let mut export_names = HashSet::with_capacity(export_section.entries().len());
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for export in export_section.entries() {
// HashSet::insert returns false if item already in set.
let duplicate = export_names.insert(export.field()) == false;
if duplicate {
return Err(Error(
format!("duplicate export {}", export.field()),
));
}
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match *export.internal() {
Internal::Function(function_index) => {
context.require_function(function_index)?;
}
Internal::Global(global_index) => {
context.require_global(global_index, Some(false))?;
}
Internal::Memory(memory_index) => {
context.require_memory(memory_index)?;
}
Internal::Table(table_index) => {
context.require_table(table_index)?;
}
}
}
}
// validate import section
if let Some(import_section) = module.import_section() {
for import in import_section.entries() {
match *import.external() {
External::Function(function_type_index) => {
context.require_function_type(function_type_index)?;
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}
External::Global(ref global_type) => {
if global_type.is_mutable() {
return Err(Error(format!(
"trying to import mutable global {}",
import.field()
)));
}
}
External::Memory(ref memory_type) => {
validate_memory_type(memory_type)?;
}
External::Table(ref table_type) => {
validate_table_type(table_type)?;
}
}
}
}
// there must be no greater than 1 table in tables index space
if context.tables().len() > 1 {
return Err(Error(format!(
"too many tables in index space: {}",
context.tables().len()
)));
}
// there must be no greater than 1 linear memory in memory index space
if context.memories().len() > 1 {
return Err(Error(format!(
"too many memory regions in index space: {}",
context.memories().len()
)));
}
// use data section to initialize linear memory regions
if let Some(data_section) = module.data_section() {
for data_segment in data_section.entries() {
context.require_memory(data_segment.index())?;
let init_ty = expr_const_type(data_segment.offset(), context.globals())?;
if init_ty != ValueType::I32 {
return Err(Error("segment offset should return I32".into()));
}
}
}
// use element section to fill tables
if let Some(element_section) = module.elements_section() {
for element_segment in element_section.entries() {
context.require_table(element_segment.index())?;
let init_ty = expr_const_type(element_segment.offset(), context.globals())?;
if init_ty != ValueType::I32 {
return Err(Error("segment offset should return I32".into()));
}
for function_index in element_segment.members() {
context.require_function(*function_index)?;
}
}
}
Ok(ValidatedModule {
module,
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code_map,
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})
}
fn validate_limits(limits: &ResizableLimits) -> Result<(), Error> {
if let Some(maximum) = limits.maximum() {
if limits.initial() > maximum {
return Err(Error(format!(
"maximum limit {} is less than minimum {}",
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maximum,
limits.initial()
)));
}
}
Ok(())
}
fn validate_memory_type(memory_type: &MemoryType) -> Result<(), Error> {
let initial: Pages = Pages(memory_type.limits().initial() as usize);
let maximum: Option<Pages> = memory_type.limits().maximum().map(|m| Pages(m as usize));
::memory::validate_memory(initial, maximum).map_err(Error)
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}
fn validate_table_type(table_type: &TableType) -> Result<(), Error> {
validate_limits(table_type.limits())
}
fn validate_global_entry(global_entry: &GlobalEntry, globals: &[GlobalType]) -> Result<(), Error> {
let init = global_entry.init_expr();
let init_expr_ty = expr_const_type(init, globals)?;
if init_expr_ty != global_entry.global_type().content_type() {
return Err(Error(format!(
"Trying to initialize variable of type {:?} with value of type {:?}",
global_entry.global_type().content_type(),
init_expr_ty
)));
}
Ok(())
}
/// Returns type of this constant expression.
fn expr_const_type(init_expr: &InitExpr, globals: &[GlobalType]) -> Result<ValueType, Error> {
let code = init_expr.code();
if code.len() != 2 {
return Err(Error(
"Init expression should always be with length 2".into(),
));
}
let expr_ty: ValueType = match code[0] {
Opcode::I32Const(_) => ValueType::I32,
Opcode::I64Const(_) => ValueType::I64,
Opcode::F32Const(_) => ValueType::F32,
Opcode::F64Const(_) => ValueType::F64,
Opcode::GetGlobal(idx) => {
match globals.get(idx as usize) {
Some(target_global) => {
if target_global.is_mutable() {
return Err(Error(format!("Global {} is mutable", idx)));
}
target_global.content_type()
}
None => {
return Err(Error(
format!("Global {} doesn't exists or not yet defined", idx),
))
}
}
}
_ => return Err(Error("Non constant opcode in init expr".into())),
};
if code[1] != Opcode::End {
return Err(Error("Expression doesn't ends with `end` opcode".into()));
}
Ok(expr_ty)
}