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Add resource limiting to the Wasmtime API. (#2736)

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* Add resource limiting to the Wasmtime API.

This commit adds a `ResourceLimiter` trait to the Wasmtime API.

When used in conjunction with `Store::new_with_limiter`, this can be used to
monitor and prevent WebAssembly code from growing linear memories and tables.

This is particularly useful when hosts need to take into account host resource
usage to determine if WebAssembly code can consume more resources.

A simple `StaticResourceLimiter` is also included with these changes that will
simply limit the size of linear memories or tables for all instances created in
the store based on static values.

* Code review feedback.

* Implemented `StoreLimits` and `StoreLimitsBuilder`.
* Moved `max_instances`, `max_memories`, `max_tables` out of `Config` and into
  `StoreLimits`.
* Moved storage of the limiter in the runtime into `Memory` and `Table`.
* Made `InstanceAllocationRequest` use a reference to the limiter.
* Updated docs.
* Made `ResourceLimiterProxy` generic to remove a level of indirection.
* Fixed the limiter not being used for `wasmtime::Memory` and
  `wasmtime::Table`.

* Code review feedback and bug fix.

* `Memory::new` now returns `Result<Self>` so that an error can be returned if
  the initial requested memory exceeds any limits placed on the store.

* Changed an `Arc` to `Rc` as the `Arc` wasn't necessary.

* Removed `Store` from the `ResourceLimiter` callbacks. Custom resource limiter
  implementations are free to capture any context they want, so no need to
  unnecessarily store a weak reference to `Store` from the proxy type.

* Fixed a bug in the pooling instance allocator where an instance would be
  leaked from the pool. Previously, this would only have happened if the OS was
  unable to make the necessary linear memory available for the instance. With
  these changes, however, the instance might not be created due to limits
  placed on the store. We now properly deallocate the instance on error.

* Added more tests, including one that covers the fix mentioned above.

* Code review feedback.

* Add another memory to `test_pooling_allocator_initial_limits_exceeded` to
  ensure a partially created instance is successfully deallocated.
* Update some doc comments for better documentation of `Store` and
  `ResourceLimiter`.
This commit is contained in:
Peter Huene
2021-04-19 07:19:20 -07:00
committed by GitHub
parent 52b1166918
commit f12b4c467c
30 changed files with 1063 additions and 218 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
RELEASES.md
View File

@@ -4,6 +4,19 @@
## Unreleased
### Added
* Added `Store::with_limits`, `StoreLimits`, and `ResourceLimiter` to the
Wasmtime API to help with enforcing resource limits at runtime. The
`ResourceLimiter` trait can be implemented by custom resource limiters to
decide if linear memories or tables can be grown.
### Changed
* Breaking: `Memory::new` has been changed to return `Result` as creating a
host memory object is now a fallible operation when the initial size of
the memory exceeds the store limits.
## 0.26.0
Released 2021-04-05.

5
crates/c-api/src/config.rs
View File

@@ -176,8 +176,3 @@ pub extern "C" fn wasmtime_config_static_memory_guard_size_set(c: &mut wasm_conf
pub extern "C" fn wasmtime_config_dynamic_memory_guard_size_set(c: &mut wasm_config_t, size: u64) {
c.config.dynamic_memory_guard_size(size);
}
#[no_mangle]
pub extern "C" fn wasmtime_config_max_instances_set(c: &mut wasm_config_t, limit: usize) {
c.config.max_instances(limit);
}

8
crates/c-api/src/memory.rs
View File

@@ -31,13 +31,13 @@ impl wasm_memory_t {
pub extern "C" fn wasm_memory_new(
store: &wasm_store_t,
mt: &wasm_memorytype_t,
) -> Box<wasm_memory_t> {
let memory = Memory::new(&store.store, mt.ty().ty.clone());
Box::new(wasm_memory_t {
) -> Option<Box<wasm_memory_t>> {
let memory = Memory::new(&store.store, mt.ty().ty.clone()).ok()?;
Some(Box::new(wasm_memory_t {
ext: wasm_extern_t {
which: memory.into(),
},
})
}))
}
#[no_mangle]

7
crates/fuzzing/src/lib.rs
View File

@@ -39,13 +39,6 @@ pub fn fuzz_default_config(strategy: wasmtime::Strategy) -> anyhow::Result<wasmt
.wasm_bulk_memory(true)
.wasm_reference_types(true)
.wasm_module_linking(true)
// The limits here are chosen based on the default "maximum type size"
// configured in wasm-smith, which is 1000. This means that instances
// are allowed to, for example, export up to 1000 memories. We bump that
// a little bit here to give us some slop.
.max_instances(1100)
.max_tables(1100)
.max_memories(1100)
.strategy(strategy)?;
Ok(config)
}

27
crates/fuzzing/src/oracles.rs
View File

@@ -44,6 +44,21 @@ fn log_wasm(wasm: &[u8]) {
}
}
fn create_store(engine: &Engine) -> Store {
Store::new_with_limits(
&engine,
StoreLimitsBuilder::new()
// The limits here are chosen based on the default "maximum type size"
// configured in wasm-smith, which is 1000. This means that instances
// are allowed to, for example, export up to 1000 memories. We bump that
// a little bit here to give us some slop.
.instances(1100)
.tables(1100)
.memories(1100)
.build(),
)
}
/// Methods of timing out execution of a WebAssembly module
#[derive(Debug)]
pub enum Timeout {
@@ -95,7 +110,7 @@ pub fn instantiate_with_config(
_ => false,
});
let engine = Engine::new(&config).unwrap();
let store = Store::new(&engine);
let store = create_store(&engine);
let mut timeout_state = SignalOnDrop::default();
match timeout {
@@ -203,7 +218,7 @@ pub fn differential_execution(
config.wasm_module_linking(false);
let engine = Engine::new(&config).unwrap();
let store = Store::new(&engine);
let store = create_store(&engine);
let module = Module::new(&engine, &wasm).unwrap();
@@ -348,7 +363,7 @@ pub fn make_api_calls(api: crate::generators::api::ApiCalls) {
ApiCall::StoreNew => {
log::trace!("creating store");
assert!(store.is_none());
store = Some(Store::new(engine.as_ref().unwrap()));
store = Some(create_store(engine.as_ref().unwrap()));
}
ApiCall::ModuleNew { id, wasm } => {
@@ -439,7 +454,7 @@ pub fn spectest(fuzz_config: crate::generators::Config, test: crate::generators:
config.wasm_reference_types(false);
config.wasm_bulk_memory(false);
config.wasm_module_linking(false);
let store = Store::new(&Engine::new(&config).unwrap());
let store = create_store(&Engine::new(&config).unwrap());
if fuzz_config.consume_fuel {
store.add_fuel(u64::max_value()).unwrap();
}
@@ -463,7 +478,7 @@ pub fn table_ops(
let mut config = fuzz_config.to_wasmtime();
config.wasm_reference_types(true);
let engine = Engine::new(&config).unwrap();
let store = Store::new(&engine);
let store = create_store(&engine);
if fuzz_config.consume_fuel {
store.add_fuel(u64::max_value()).unwrap();
}
@@ -578,7 +593,7 @@ pub fn differential_wasmi_execution(wasm: &[u8], config: &crate::generators::Con
let mut wasmtime_config = config.to_wasmtime();
wasmtime_config.cranelift_nan_canonicalization(true);
let wasmtime_engine = Engine::new(&wasmtime_config).unwrap();
let wasmtime_store = Store::new(&wasmtime_engine);
let wasmtime_store = create_store(&wasmtime_engine);
if config.consume_fuel {
wasmtime_store.add_fuel(u64::max_value()).unwrap();
}

2
crates/fuzzing/src/oracles/dummy.rs
View File

@@ -87,7 +87,7 @@ pub fn dummy_table(store: &Store, ty: TableType) -> Table {
/// Construct a dummy memory for the given memory type.
pub fn dummy_memory(store: &Store, ty: MemoryType) -> Memory {
Memory::new(store, ty)
Memory::new(store, ty).unwrap()
}
/// Construct a dummy instance for the given instance type.

78
crates/runtime/src/instance.rs
View File

@@ -37,6 +37,52 @@ mod allocator;
pub use allocator::*;
/// Used by hosts to limit resource consumption of instances.
///
/// An instance can be created with a resource limiter so that hosts can take into account
/// non-WebAssembly resource usage to determine if a linear memory or table should grow.
pub trait ResourceLimiter {
/// Notifies the resource limiter that an instance's linear memory has been requested to grow.
///
/// * `current` is the current size of the linear memory in WebAssembly page units.
/// * `desired` is the desired size of the linear memory in WebAssembly page units.
/// * `maximum` is either the linear memory's maximum or a maximum from an instance allocator,
/// also in WebAssembly page units. A value of `None` indicates that the linear memory is
/// unbounded.
///
/// This function should return `true` to indicate that the growing operation is permitted or
/// `false` if not permitted. Returning `true` when a maximum has been exceeded will have no
/// effect as the linear memory will not grow.
fn memory_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool;
/// Notifies the resource limiter that an instance's table has been requested to grow.
///
/// * `current` is the current number of elements in the table.
/// * `desired` is the desired number of elements in the table.
/// * `maximum` is either the table's maximum or a maximum from an instance allocator.
/// A value of `None` indicates that the table is unbounded.
///
/// This function should return `true` to indicate that the growing operation is permitted or
/// `false` if not permitted. Returning `true` when a maximum has been exceeded will have no
/// effect as the table will not grow.
fn table_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool;
/// The maximum number of instances that can be created for a `Store`.
///
/// Module instantiation will fail if this limit is exceeded.
fn instances(&self) -> usize;
/// The maximum number of tables that can be created for a `Store`.
///
/// Module instantiation will fail if this limit is exceeded.
fn tables(&self) -> usize;
/// The maximum number of tables that can be created for a `Store`.
///
/// Module instantiation will fail if this limit is exceeded.
fn memories(&self) -> usize;
}
/// Runtime representation of an instance value, which erases all `Instance`
/// information since instances are just a collection of values.
pub type RuntimeInstance = Rc<IndexMap<String, Export>>;
@@ -378,11 +424,12 @@ impl Instance {
/// Returns `None` if memory can't be grown by the specified amount
/// of pages.
pub(crate) fn memory_grow(&self, memory_index: DefinedMemoryIndex, delta: u32) -> Option<u32> {
let result = self
let memory = self
.memories
.get(memory_index)
.unwrap_or_else(|| panic!("no memory for index {}", memory_index.index()))
.grow(delta);
.unwrap_or_else(|| panic!("no memory for index {}", memory_index.index()));
let result = unsafe { memory.grow(delta) };
// Keep current the VMContext pointers used by compiled wasm code.
self.set_memory(memory_index, self.memories[memory_index].vmmemory());
@@ -460,19 +507,18 @@ impl Instance {
delta: u32,
init_value: TableElement,
) -> Option<u32> {
unsafe {
let orig_size = self
.tables
.get(table_index)
.unwrap_or_else(|| panic!("no table for index {}", table_index.index()))
.grow(delta, init_value)?;
let table = self
.tables
.get(table_index)
.unwrap_or_else(|| panic!("no table for index {}", table_index.index()));
// Keep the `VMContext` pointers used by compiled Wasm code up to
// date.
self.set_table(table_index, self.tables[table_index].vmtable());
let result = unsafe { table.grow(delta, init_value) };
Some(orig_size)
}
// Keep the `VMContext` pointers used by compiled Wasm code up to
// date.
self.set_table(table_index, self.tables[table_index].vmtable());
result
}
pub(crate) fn defined_table_fill(
@@ -818,10 +864,6 @@ pub struct InstanceHandle {
}
impl InstanceHandle {
pub(crate) unsafe fn new(instance: *mut Instance) -> Self {
Self { instance }
}
/// Create a new `InstanceHandle` pointing at the instance
/// pointed to by the given `VMContext` pointer.
///

30
crates/runtime/src/instance/allocator.rs
View File

@@ -1,6 +1,6 @@
use crate::externref::{ModuleInfoLookup, VMExternRefActivationsTable, EMPTY_MODULE_LOOKUP};
use crate::imports::Imports;
use crate::instance::{Instance, InstanceHandle, RuntimeMemoryCreator};
use crate::instance::{Instance, InstanceHandle, ResourceLimiter, RuntimeMemoryCreator};
use crate::memory::{DefaultMemoryCreator, Memory};
use crate::table::{Table, TableElement};
use crate::traphandlers::Trap;
@@ -15,6 +15,7 @@ use std::any::Any;
use std::cell::RefCell;
use std::convert::TryFrom;
use std::ptr::{self, NonNull};
use std::rc::Rc;
use std::slice;
use std::sync::Arc;
use thiserror::Error;
@@ -59,6 +60,9 @@ pub struct InstanceAllocationRequest<'a> {
/// The pointer to the module info lookup to use for the instance.
pub module_info_lookup: Option<*const dyn ModuleInfoLookup>,
/// The resource limiter to use for the instance.
pub limiter: Option<&'a Rc<dyn ResourceLimiter>>,
}
/// An link error while instantiating a module.
@@ -590,19 +594,23 @@ impl OnDemandInstanceAllocator {
}
}
fn create_tables(module: &Module) -> PrimaryMap<DefinedTableIndex, Table> {
fn create_tables(
module: &Module,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<PrimaryMap<DefinedTableIndex, Table>, InstantiationError> {
let num_imports = module.num_imported_tables;
let mut tables: PrimaryMap<DefinedTableIndex, _> =
PrimaryMap::with_capacity(module.table_plans.len() - num_imports);
for table in &module.table_plans.values().as_slice()[num_imports..] {
tables.push(Table::new_dynamic(table));
tables.push(Table::new_dynamic(table, limiter).map_err(InstantiationError::Resource)?);
}
tables
Ok(tables)
}
fn create_memories(
&self,
module: &Module,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<PrimaryMap<DefinedMemoryIndex, Memory>, InstantiationError> {
let creator = self
.mem_creator
@@ -612,8 +620,10 @@ impl OnDemandInstanceAllocator {
let mut memories: PrimaryMap<DefinedMemoryIndex, _> =
PrimaryMap::with_capacity(module.memory_plans.len() - num_imports);
for plan in &module.memory_plans.values().as_slice()[num_imports..] {
memories
.push(Memory::new_dynamic(plan, creator).map_err(InstantiationError::Resource)?);
memories.push(
Memory::new_dynamic(plan, creator, limiter)
.map_err(InstantiationError::Resource)?,
);
}
Ok(memories)
}
@@ -633,8 +643,8 @@ unsafe impl InstanceAllocator for OnDemandInstanceAllocator {
&self,
mut req: InstanceAllocationRequest,
) -> Result<InstanceHandle, InstantiationError> {
let memories = self.create_memories(&req.module)?;
let tables = Self::create_tables(&req.module);
let memories = self.create_memories(&req.module, req.limiter)?;
let tables = Self::create_tables(&req.module, req.limiter)?;
let host_state = std::mem::replace(&mut req.host_state, Box::new(()));
@@ -657,7 +667,9 @@ unsafe impl InstanceAllocator for OnDemandInstanceAllocator {
alloc::handle_alloc_error(layout);
}
ptr::write(instance_ptr, instance);
InstanceHandle::new(instance_ptr)
InstanceHandle {
instance: instance_ptr,
}
};
initialize_vmcontext(handle.instance(), req);

81
crates/runtime/src/instance/allocator/pooling.rs
View File

@@ -9,7 +9,7 @@
use super::{
initialize_instance, initialize_vmcontext, InstanceAllocationRequest, InstanceAllocator,
InstanceHandle, InstantiationError,
InstanceHandle, InstantiationError, ResourceLimiter,
};
use crate::{instance::Instance, Memory, Mmap, Table, VMContext};
use anyhow::{anyhow, bail, Context, Result};
@@ -18,6 +18,7 @@ use std::cell::RefCell;
use std::cmp::min;
use std::convert::TryFrom;
use std::mem;
use std::rc::Rc;
use std::sync::{Arc, Mutex};
use wasmtime_environ::{
entity::{EntitySet, PrimaryMap},
@@ -376,10 +377,45 @@ impl InstancePool {
}
}
unsafe fn setup_instance(
&self,
index: usize,
mut req: InstanceAllocationRequest,
) -> Result<InstanceHandle, InstantiationError> {
let instance = self.instance(index);
instance.module = req.module.clone();
instance.offsets = VMOffsets::new(
std::mem::size_of::<*const u8>() as u8,
instance.module.as_ref(),
);
instance.host_state = std::mem::replace(&mut req.host_state, Box::new(()));
Self::set_instance_memories(
instance,
self.memories.get(index),
self.memories.max_wasm_pages,
req.limiter,
)?;
Self::set_instance_tables(
instance,
self.tables.get(index),
self.tables.max_elements,
req.limiter,
)?;
initialize_vmcontext(instance, req);
Ok(InstanceHandle {
instance: instance as _,
})
}
fn allocate(
&self,
strategy: PoolingAllocationStrategy,
mut req: InstanceAllocationRequest,
req: InstanceAllocationRequest,
) -> Result<InstanceHandle, InstantiationError> {
let index = {
let mut free_list = self.free_list.lock().unwrap();
@@ -390,28 +426,15 @@ impl InstancePool {
free_list.swap_remove(free_index)
};
let host_state = std::mem::replace(&mut req.host_state, Box::new(()));
unsafe {
let instance = self.instance(index);
instance.module = req.module.clone();
instance.offsets = VMOffsets::new(
std::mem::size_of::<*const u8>() as u8,
instance.module.as_ref(),
);
instance.host_state = host_state;
Self::set_instance_memories(
instance,
self.memories.get(index),
self.memories.max_wasm_pages,
)?;
Self::set_instance_tables(instance, self.tables.get(index), self.tables.max_elements)?;
initialize_vmcontext(instance, req);
Ok(InstanceHandle::new(instance as _))
self.setup_instance(index, req).or_else(|e| {
// Deallocate the allocated instance on error
let instance = self.instance(index);
self.deallocate(&InstanceHandle {
instance: instance as _,
});
Err(e)
})
}
}
@@ -473,6 +496,7 @@ impl InstancePool {
instance: &mut Instance,
mut memories: impl Iterator<Item = *mut u8>,
max_pages: u32,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<(), InstantiationError> {
let module = instance.module.as_ref();
@@ -487,6 +511,7 @@ impl InstancePool {
memories.next().unwrap(),
max_pages,
commit_memory_pages,
limiter,
)
.map_err(InstantiationError::Resource)?,
);
@@ -503,6 +528,7 @@ impl InstancePool {
instance: &mut Instance,
mut tables: impl Iterator<Item = *mut u8>,
max_elements: u32,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<(), InstantiationError> {
let module = instance.module.as_ref();
@@ -514,9 +540,10 @@ impl InstancePool {
commit_table_pages(base, max_elements as usize * mem::size_of::<*mut u8>())
.map_err(InstantiationError::Resource)?;
instance
.tables
.push(Table::new_static(plan, base as _, max_elements));
instance.tables.push(
Table::new_static(plan, base as _, max_elements, limiter)
.map_err(InstantiationError::Resource)?,
);
}
let mut dropped_elements = instance.dropped_elements.borrow_mut();
@@ -1371,6 +1398,7 @@ mod test {
interrupts: std::ptr::null(),
externref_activations_table: std::ptr::null_mut(),
module_info_lookup: None,
limiter: None,
},
)
.expect("allocation should succeed"),
@@ -1395,6 +1423,7 @@ mod test {
interrupts: std::ptr::null(),
externref_activations_table: std::ptr::null_mut(),
module_info_lookup: None,
limiter: None,
},
) {
Err(InstantiationError::Limit(3)) => {}

1
crates/runtime/src/instance/allocator/pooling/uffd.rs
View File

@@ -524,6 +524,7 @@ mod test {
interrupts: ptr::null(),
externref_activations_table: ptr::null_mut(),
module_info_lookup: None,
limiter: None,
},
)
.expect("instance should allocate"),

2
crates/runtime/src/lib.rs
View File

@@ -40,7 +40,7 @@ pub use crate::imports::Imports;
pub use crate::instance::{
InstanceAllocationRequest, InstanceAllocator, InstanceHandle, InstanceLimits,
InstantiationError, LinkError, ModuleLimits, OnDemandInstanceAllocator,
PoolingAllocationStrategy, PoolingInstanceAllocator, RuntimeInstance,
PoolingAllocationStrategy, PoolingInstanceAllocator, ResourceLimiter, RuntimeInstance,
};
pub use crate::jit_int::GdbJitImageRegistration;
pub use crate::memory::{Memory, RuntimeLinearMemory, RuntimeMemoryCreator};

153
crates/runtime/src/memory.rs
View File

@@ -4,12 +4,14 @@
use crate::mmap::Mmap;
use crate::vmcontext::VMMemoryDefinition;
use anyhow::Result;
use crate::ResourceLimiter;
use anyhow::{bail, Result};
use more_asserts::{assert_ge, assert_le};
use std::cell::{Cell, RefCell};
use std::cmp::min;
use std::convert::TryFrom;
use std::ptr;
use std::rc::Rc;
use wasmtime_environ::{MemoryPlan, MemoryStyle, WASM_MAX_PAGES, WASM_PAGE_SIZE};
/// A memory allocator
@@ -33,6 +35,10 @@ pub trait RuntimeLinearMemory {
/// Returns the number of allocated wasm pages.
fn size(&self) -> u32;
/// Returns the maximum number of pages the memory can grow to.
/// Returns `None` if the memory is unbounded.
fn maximum(&self) -> Option<u32>;
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
@@ -105,6 +111,12 @@ impl RuntimeLinearMemory for MmapMemory {
self.mmap.borrow().size
}
/// Returns the maximum number of pages the memory can grow to.
/// Returns `None` if the memory is unbounded.
fn maximum(&self) -> Option<u32> {
self.maximum
}
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
@@ -189,12 +201,23 @@ enum MemoryStorage {
}
/// Represents an instantiation of a WebAssembly memory.
pub struct Memory(MemoryStorage);
pub struct Memory {
storage: MemoryStorage,
limiter: Option<Rc<dyn ResourceLimiter>>,
}
impl Memory {
/// Create a new dynamic (movable) memory instance for the specified plan.
pub fn new_dynamic(plan: &MemoryPlan, creator: &dyn RuntimeMemoryCreator) -> Result<Self> {
Ok(Self(MemoryStorage::Dynamic(creator.new_memory(plan)?)))
pub fn new_dynamic(
plan: &MemoryPlan,
creator: &dyn RuntimeMemoryCreator,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<Self> {
Self::new(
plan,
MemoryStorage::Dynamic(creator.new_memory(plan)?),
limiter,
)
}
/// Create a new static (immovable) memory instance for the specified plan.
@@ -203,32 +226,78 @@ impl Memory {
base: *mut u8,
maximum: u32,
make_accessible: fn(*mut u8, usize) -> Result<()>,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<Self> {
if plan.memory.minimum > 0 {
make_accessible(base, plan.memory.minimum as usize * WASM_PAGE_SIZE as usize)?;
}
Ok(Self(MemoryStorage::Static {
let storage = MemoryStorage::Static {
base,
size: Cell::new(plan.memory.minimum),
maximum: min(plan.memory.maximum.unwrap_or(maximum), maximum),
make_accessible,
#[cfg(all(feature = "uffd", target_os = "linux"))]
guard_page_faults: RefCell::new(Vec::new()),
}))
};
Self::new(plan, storage, limiter)
}
fn new(
plan: &MemoryPlan,
storage: MemoryStorage,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<Self> {
if let Some(limiter) = limiter {
if !limiter.memory_growing(0, plan.memory.minimum, plan.memory.maximum) {
bail!(
"memory minimum size of {} pages exceeds memory limits",
plan.memory.minimum
);
}
}
if let MemoryStorage::Static {
base,
make_accessible,
..
} = &storage
{
if plan.memory.minimum > 0 {
make_accessible(
*base,
plan.memory.minimum as usize * WASM_PAGE_SIZE as usize,
)?;
}
}
Ok(Self {
storage,
limiter: limiter.cloned(),
})
}
/// Returns the number of allocated wasm pages.
pub fn size(&self) -> u32 {
match &self.0 {
match &self.storage {
MemoryStorage::Static { size, .. } => size.get(),
MemoryStorage::Dynamic(mem) => mem.size(),
}
}
/// Returns the maximum number of pages the memory can grow to at runtime.
///
/// Returns `None` if the memory is unbounded.
///
/// The runtime maximum may not be equal to the maximum from the linear memory's
/// Wasm type when it is being constrained by an instance allocator.
pub fn maximum(&self) -> Option<u32> {
match &self.storage {
MemoryStorage::Static { maximum, .. } => Some(*maximum),
MemoryStorage::Dynamic(mem) => mem.maximum(),
}
}
/// Returns whether or not the underlying storage of the memory is "static".
pub(crate) fn is_static(&self) -> bool {
if let MemoryStorage::Static { .. } = &self.0 {
if let MemoryStorage::Static { .. } = &self.storage {
true
} else {
false
@@ -239,8 +308,30 @@ impl Memory {
///
/// Returns `None` if memory can't be grown by the specified amount
/// of wasm pages.
pub fn grow(&self, delta: u32) -> Option<u32> {
match &self.0 {
///
/// # Safety
///
/// Resizing the memory can reallocate the memory buffer for dynamic memories.
/// An instance's `VMContext` may have pointers to the memory's base and will
/// need to be fixed up after growing the memory.
///
/// Generally, prefer using `InstanceHandle::memory_grow`, which encapsulates
/// this unsafety.
pub unsafe fn grow(&self, delta: u32) -> Option<u32> {
let old_size = self.size();
if delta == 0 {
return Some(old_size);
}
let new_size = old_size.checked_add(delta)?;
if let Some(limiter) = &self.limiter {
if !limiter.memory_growing(old_size, new_size, self.maximum()) {
return None;
}
}
match &self.storage {
MemoryStorage::Static {
base,
size,
@@ -252,13 +343,6 @@ impl Memory {
#[cfg(all(feature = "uffd", target_os = "linux"))]
self.reset_guard_pages().ok()?;
let old_size = size.get();
if delta == 0 {
return Some(old_size);
}
let new_size = old_size.checked_add(delta)?;
if new_size > *maximum || new_size >= WASM_MAX_PAGES {
return None;
}
@@ -266,7 +350,7 @@ impl Memory {
let start = usize::try_from(old_size).unwrap() * WASM_PAGE_SIZE as usize;
let len = usize::try_from(delta).unwrap() * WASM_PAGE_SIZE as usize;
make_accessible(unsafe { base.add(start) }, len).ok()?;
make_accessible(base.add(start), len).ok()?;
size.set(new_size);
@@ -278,7 +362,7 @@ impl Memory {
/// Return a `VMMemoryDefinition` for exposing the memory to compiled wasm code.
pub fn vmmemory(&self) -> VMMemoryDefinition {
match &self.0 {
match &self.storage {
MemoryStorage::Static { base, size, .. } => VMMemoryDefinition {
base: *base,
current_length: size.get() as usize * WASM_PAGE_SIZE as usize,
@@ -299,7 +383,7 @@ impl Memory {
size: usize,
reset: fn(*mut u8, usize) -> Result<()>,
) {
match &self.0 {
match &self.storage {
MemoryStorage::Static {
guard_page_faults, ..
} => {
@@ -320,7 +404,7 @@ impl Memory {
/// This function will panic if called on a dynamic memory.
#[cfg(all(feature = "uffd", target_os = "linux"))]
pub(crate) fn reset_guard_pages(&self) -> Result<()> {
match &self.0 {
match &self.storage {
MemoryStorage::Static {
guard_page_faults, ..
} => {
@@ -345,13 +429,16 @@ impl Default for Memory {
unreachable!()
}
Self(MemoryStorage::Static {
base: ptr::null_mut(),
size: Cell::new(0),
maximum: 0,
make_accessible,
#[cfg(all(feature = "uffd", target_os = "linux"))]
guard_page_faults: RefCell::new(Vec::new()),
})
Self {
storage: MemoryStorage::Static {
base: ptr::null_mut(),
size: Cell::new(0),
maximum: 0,
make_accessible,
#[cfg(all(feature = "uffd", target_os = "linux"))]
guard_page_faults: RefCell::new(Vec::new()),
},
limiter: None,
}
}
}

103
crates/runtime/src/table.rs
View File

@@ -3,19 +3,21 @@
//! `Table` is to WebAssembly tables what `LinearMemory` is to WebAssembly linear memories.
use crate::vmcontext::{VMCallerCheckedAnyfunc, VMTableDefinition};
use crate::{Trap, VMExternRef};
use crate::{ResourceLimiter, Trap, VMExternRef};
use anyhow::{bail, Result};
use std::cell::{Cell, RefCell};
use std::cmp::min;
use std::convert::TryInto;
use std::ops::Range;
use std::ptr;
use std::rc::Rc;
use wasmtime_environ::wasm::TableElementType;
use wasmtime_environ::{ir, TablePlan};
/// An element going into or coming out of a table.
///
/// Table elements are stored as pointers and are default-initialized with `ptr::null_mut`.
#[derive(Clone, Debug)]
#[derive(Clone)]
pub enum TableElement {
/// A `funcref`.
FuncRef(*mut VMCallerCheckedAnyfunc),
@@ -92,7 +94,6 @@ impl From<VMExternRef> for TableElement {
}
}
#[derive(Debug)]
enum TableStorage {
Static {
data: *mut *mut u8,
@@ -108,38 +109,74 @@ enum TableStorage {
}
/// Represents an instance's table.
#[derive(Debug)]
pub struct Table(TableStorage);
pub struct Table {
storage: TableStorage,
limiter: Option<Rc<dyn ResourceLimiter>>,
}
impl Table {
/// Create a new dynamic (movable) table instance for the specified table plan.
pub fn new_dynamic(plan: &TablePlan) -> Self {
pub fn new_dynamic(
plan: &TablePlan,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<Self> {
let elements = RefCell::new(vec![ptr::null_mut(); plan.table.minimum as usize]);
let ty = plan.table.ty.clone();
let maximum = plan.table.maximum;
Self(TableStorage::Dynamic {
let storage = TableStorage::Dynamic {
elements,
ty,
maximum,
})
};
Self::new(plan, storage, limiter)
}
/// Create a new static (immovable) table instance for the specified table plan.
pub fn new_static(plan: &TablePlan, data: *mut *mut u8, maximum: u32) -> Self {
pub fn new_static(
plan: &TablePlan,
data: *mut *mut u8,
maximum: u32,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<Self> {
let size = Cell::new(plan.table.minimum);
let ty = plan.table.ty.clone();
let maximum = min(plan.table.maximum.unwrap_or(maximum), maximum);
Self(TableStorage::Static {
let storage = TableStorage::Static {
data,
size,
ty,
maximum,
};
Self::new(plan, storage, limiter)
}
fn new(
plan: &TablePlan,
storage: TableStorage,
limiter: Option<&Rc<dyn ResourceLimiter>>,
) -> Result<Self> {
if let Some(limiter) = limiter {
if !limiter.table_growing(0, plan.table.minimum, plan.table.maximum) {
bail!(
"table minimum size of {} elements exceeds table limits",
plan.table.minimum
);
}
}
Ok(Self {
storage,
limiter: limiter.cloned(),
})
}
/// Returns the type of the elements in this table.
pub fn element_type(&self) -> TableElementType {
match &self.0 {
match &self.storage {
TableStorage::Static { ty, .. } => *ty,
TableStorage::Dynamic { ty, .. } => *ty,
}
@@ -147,7 +184,7 @@ impl Table {
/// Returns whether or not the underlying storage of the table is "static".
pub(crate) fn is_static(&self) -> bool {
if let TableStorage::Static { .. } = &self.0 {
if let TableStorage::Static { .. } = &self.storage {
true
} else {
false
@@ -156,15 +193,20 @@ impl Table {
/// Returns the number of allocated elements.
pub fn size(&self) -> u32 {
match &self.0 {
match &self.storage {
TableStorage::Static { size, .. } => size.get(),
TableStorage::Dynamic { elements, .. } => elements.borrow().len().try_into().unwrap(),
}
}
/// Returns the maximum number of elements.
/// Returns the maximum number of elements at runtime.
///
/// Returns `None` if the table is unbounded.
///
/// The runtime maximum may not be equal to the maximum from the table's Wasm type
/// when it is being constrained by an instance allocator.
pub fn maximum(&self) -> Option<u32> {
match &self.0 {
match &self.storage {
TableStorage::Static { maximum, .. } => Some(*maximum),
TableStorage::Dynamic { maximum, .. } => maximum.clone(),
}
@@ -218,8 +260,14 @@ impl Table {
/// this unsafety.
pub unsafe fn grow(&self, delta: u32, init_value: TableElement) -> Option<u32> {
let old_size = self.size();
let new_size = old_size.checked_add(delta)?;
if let Some(limiter) = &self.limiter {
if !limiter.table_growing(old_size, new_size, self.maximum()) {
return None;
}
}
if let Some(max) = self.maximum() {
if new_size > max {
return None;
@@ -229,7 +277,7 @@ impl Table {
debug_assert!(self.type_matches(&init_value));
// First resize the storage and then fill with the init value
match &self.0 {
match &self.storage {
TableStorage::Static { size, .. } => {
size.set(new_size);
}
@@ -319,7 +367,7 @@ impl Table {
/// Return a `VMTableDefinition` for exposing the table to compiled wasm code.
pub fn vmtable(&self) -> VMTableDefinition {
match &self.0 {
match &self.storage {
TableStorage::Static { data, size, .. } => VMTableDefinition {
base: *data as _,
current_elements: size.get(),
@@ -346,7 +394,7 @@ impl Table {
where
F: FnOnce(&[*mut u8]) -> R,
{
match &self.0 {
match &self.storage {
TableStorage::Static { data, size, .. } => unsafe {
f(std::slice::from_raw_parts(*data, size.get() as usize))
},
@@ -361,7 +409,7 @@ impl Table {
where
F: FnOnce(&mut [*mut u8]) -> R,
{
match &self.0 {
match &self.storage {
TableStorage::Static { data, size, .. } => unsafe {
f(std::slice::from_raw_parts_mut(*data, size.get() as usize))
},
@@ -463,11 +511,14 @@ impl Drop for Table {
// The default table representation is an empty funcref table that cannot grow.
impl Default for Table {
fn default() -> Self {
Self(TableStorage::Static {
data: std::ptr::null_mut(),
size: Cell::new(0),
ty: TableElementType::Func,
maximum: 0,
})
Self {
storage: TableStorage::Static {
data: std::ptr::null_mut(),
size: Cell::new(0),
ty: TableElementType::Func,
maximum: 0,
},
limiter: None,
}
}
}

39
crates/wasmtime/src/config.rs
View File

@@ -383,9 +383,6 @@ pub struct Config {
pub(crate) max_wasm_stack: usize,
pub(crate) features: WasmFeatures,
pub(crate) wasm_backtrace_details_env_used: bool,
pub(crate) max_instances: usize,
pub(crate) max_tables: usize,
pub(crate) max_memories: usize,
#[cfg(feature = "async")]
pub(crate) async_stack_size: usize,
host_funcs: HostFuncMap,
@@ -422,9 +419,6 @@ impl Config {
max_wasm_stack: 1 << 20,
wasm_backtrace_details_env_used: false,
features: WasmFeatures::default(),
max_instances: 10_000,
max_tables: 10_000,
max_memories: 10_000,
#[cfg(feature = "async")]
async_stack_size: 2 << 20,
host_funcs: HostFuncMap::new(),
@@ -1196,39 +1190,6 @@ impl Config {
self
}
/// Configures the maximum number of instances which can be created within
/// this `Store`.
///
/// Instantiation will fail with an error if this limit is exceeded.
///
/// This value defaults to 10,000.
pub fn max_instances(&mut self, instances: usize) -> &mut Self {
self.max_instances = instances;
self
}
/// Configures the maximum number of tables which can be created within
/// this `Store`.
///
/// Instantiation will fail with an error if this limit is exceeded.
///
/// This value defaults to 10,000.
pub fn max_tables(&mut self, tables: usize) -> &mut Self {
self.max_tables = tables;
self
}
/// Configures the maximum number of memories which can be created within
/// this `Store`.
///
/// Instantiation will fail with an error if this limit is exceeded.
///
/// This value defaults to 10,000.
pub fn max_memories(&mut self, memories: usize) -> &mut Self {
self.max_memories = memories;
self
}
/// Defines a host function for the [`Config`] for the given callback.
///
/// Use [`Store::get_host_func`](crate::Store::get_host_func) to get a [`Func`](crate::Func) representing the function.

1
crates/wasmtime/src/instance.rs
View File

@@ -525,6 +525,7 @@ impl<'a> Instantiator<'a> {
as *const VMExternRefActivationsTable
as *mut _,
module_info_lookup: Some(self.store.module_info_lookup()),
limiter: self.store.limiter().as_ref(),
})?;
// After we've created the `InstanceHandle` we still need to run

2
crates/wasmtime/src/lib.rs
View File

@@ -283,6 +283,7 @@ mod config;
mod engine;
mod externals;
mod instance;
mod limits;
mod linker;
mod memory;
mod module;
@@ -299,6 +300,7 @@ pub use crate::engine::*;
pub use crate::externals::*;
pub use crate::func::*;
pub use crate::instance::Instance;
pub use crate::limits::*;
pub use crate::linker::*;
pub use crate::memory::*;
pub use crate::module::{FrameInfo, FrameSymbol, Module};

208
crates/wasmtime/src/limits.rs Normal file
View File

@@ -0,0 +1,208 @@
pub(crate) const DEFAULT_INSTANCE_LIMIT: usize = 10000;
pub(crate) const DEFAULT_TABLE_LIMIT: usize = 10000;
pub(crate) const DEFAULT_MEMORY_LIMIT: usize = 10000;
/// Used by hosts to limit resource consumption of instances at runtime.
///
/// [`Store::new_with_limits`](crate::Store::new_with_limits) can be used
/// with a resource limiter to take into account non-WebAssembly resource
/// usage to determine if a linear memory or table should be grown.
pub trait ResourceLimiter {
/// Notifies the resource limiter that an instance's linear memory has been requested to grow.
///
/// * `current` is the current size of the linear memory in WebAssembly page units.
/// * `desired` is the desired size of the linear memory in WebAssembly page units.
/// * `maximum` is either the linear memory's maximum or a maximum from an instance allocator,
/// also in WebAssembly page units. A value of `None` indicates that the linear memory is
/// unbounded.
///
/// This function should return `true` to indicate that the growing operation is permitted or
/// `false` if not permitted.
///
/// Note that this function will be called even when the desired count exceeds the given maximum.
///
/// Returning `true` when a maximum has been exceeded will have no effect as the linear memory
/// will not be grown.
fn memory_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool;
/// Notifies the resource limiter that an instance's table has been requested to grow.
///
/// * `current` is the current number of elements in the table.
/// * `desired` is the desired number of elements in the table.
/// * `maximum` is either the table's maximum or a maximum from an instance allocator,
/// A value of `None` indicates that the table is unbounded.
///
/// This function should return `true` to indicate that the growing operation is permitted or
/// `false` if not permitted.
///
/// Note that this function will be called even when the desired count exceeds the given maximum.
///
/// Returning `true` when a maximum has been exceeded will have no effect as the table will
/// not be grown.
fn table_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool;
/// The maximum number of instances that can be created for a [`Store`](crate::Store).
///
/// Module instantiation will fail if this limit is exceeded.
///
/// This value defaults to 10,000.
fn instances(&self) -> usize {
DEFAULT_INSTANCE_LIMIT
}
/// The maximum number of tables that can be created for a [`Store`](crate::Store).
///
/// Module instantiation will fail if this limit is exceeded.
///
/// This value defaults to 10,000.
fn tables(&self) -> usize {
DEFAULT_TABLE_LIMIT
}
/// The maximum number of linear memories that can be created for a [`Store`](crate::Store).
///
/// Instantiation will fail with an error if this limit is exceeded.
///
/// This value defaults to 10,000.
fn memories(&self) -> usize {
DEFAULT_MEMORY_LIMIT
}
}
pub(crate) struct ResourceLimiterProxy<T>(pub T);
impl<T: ResourceLimiter> wasmtime_runtime::ResourceLimiter for ResourceLimiterProxy<T> {
fn memory_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool {
self.0.memory_growing(current, desired, maximum)
}
fn table_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool {
self.0.table_growing(current, desired, maximum)
}
fn instances(&self) -> usize {
self.0.instances()
}
fn tables(&self) -> usize {
self.0.tables()
}
fn memories(&self) -> usize {
self.0.memories()
}
}
/// Used to build [`StoreLimits`].
pub struct StoreLimitsBuilder(StoreLimits);
impl StoreLimitsBuilder {
/// Creates a new [`StoreLimitsBuilder`].
pub fn new() -> Self {
Self(StoreLimits::default())
}
/// The maximum number of WebAssembly pages a linear memory can grow to.
///
/// Growing a linear memory beyond this limit will fail.
///
/// By default, linear memory pages will not be limited.
pub fn memory_pages(mut self, limit: u32) -> Self {
self.0.memory_pages = Some(limit);
self
}
/// The maximum number of elements in a table.
///
/// Growing a table beyond this limit will fail.
///
/// By default, table elements will not be limited.
pub fn table_elements(mut self, limit: u32) -> Self {
self.0.table_elements = Some(limit);
self
}
/// The maximum number of instances that can be created for a [`Store`](crate::Store).
///
/// Module instantiation will fail if this limit is exceeded.
///
/// This value defaults to 10,000.
pub fn instances(mut self, limit: usize) -> Self {
self.0.instances = limit;
self
}
/// The maximum number of tables that can be created for a [`Store`](crate::Store).
///
/// Module instantiation will fail if this limit is exceeded.
///
/// This value defaults to 10,000.
pub fn tables(mut self, tables: usize) -> Self {
self.0.tables = tables;
self
}
/// The maximum number of linear memories that can be created for a [`Store`](crate::Store).
///
/// Instantiation will fail with an error if this limit is exceeded.
///
/// This value defaults to 10,000.
pub fn memories(mut self, memories: usize) -> Self {
self.0.memories = memories;
self
}
/// Consumes this builder and returns the [`StoreLimits`].
pub fn build(self) -> StoreLimits {
self.0
}
}
/// Provides limits for a [`Store`](crate::Store).
pub struct StoreLimits {
memory_pages: Option<u32>,
table_elements: Option<u32>,
instances: usize,
tables: usize,
memories: usize,
}
impl Default for StoreLimits {
fn default() -> Self {
Self {
memory_pages: None,
table_elements: None,
instances: DEFAULT_INSTANCE_LIMIT,
tables: DEFAULT_TABLE_LIMIT,
memories: DEFAULT_MEMORY_LIMIT,
}
}
}
impl ResourceLimiter for StoreLimits {
fn memory_growing(&self, _current: u32, desired: u32, _maximum: Option<u32>) -> bool {
match self.memory_pages {
Some(limit) if desired > limit => false,
_ => true,
}
}
fn table_growing(&self, _current: u32, desired: u32, _maximum: Option<u32>) -> bool {
match self.table_elements {
Some(limit) if desired > limit => false,
_ => true,
}
}
fn instances(&self) -> usize {
self.instances
}
fn tables(&self) -> usize {
self.tables
}
fn memories(&self) -> usize {
self.memories
}
}

19
crates/wasmtime/src/memory.rs
View File

@@ -262,7 +262,7 @@ impl Memory {
/// let store = Store::new(&engine);
///
/// let memory_ty = MemoryType::new(Limits::new(1, None));
/// let memory = Memory::new(&store, memory_ty);
/// let memory = Memory::new(&store, memory_ty)?;
///
/// let module = Module::new(&engine, "(module (memory (import \"\" \"\") 1))")?;
/// let instance = Instance::new(&store, &module, &[memory.into()])?;
@@ -270,13 +270,12 @@ impl Memory {
/// # Ok(())
/// # }
/// ```
pub fn new(store: &Store, ty: MemoryType) -> Memory {
let (instance, wasmtime_export) =
generate_memory_export(store, &ty).expect("generated memory");
Memory {
pub fn new(store: &Store, ty: MemoryType) -> Result<Memory> {
let (instance, wasmtime_export) = generate_memory_export(store, &ty)?;
Ok(Memory {
instance,
wasmtime_export,
}
})
}
/// Returns the underlying type of this memory.
@@ -454,7 +453,7 @@ impl Memory {
.memory_index(unsafe { &*self.wasmtime_export.definition });
self.instance
.memory_grow(index, delta)
.ok_or_else(|| anyhow!("failed to grow memory"))
.ok_or_else(|| anyhow!("failed to grow memory by `{}`", delta))
}
pub(crate) unsafe fn from_wasmtime_memory(
@@ -500,6 +499,10 @@ pub unsafe trait LinearMemory {
/// Returns the number of allocated wasm pages.
fn size(&self) -> u32;
/// Returns the maximum number of pages the memory can grow to.
/// Returns `None` if the memory is unbounded.
fn maximum(&self) -> Option<u32>;
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
@@ -568,7 +571,7 @@ mod tests {
.dynamic_memory_guard_size(0);
let store = Store::new(&Engine::new(&cfg).unwrap());
let ty = MemoryType::new(Limits::new(1, None));
let mem = Memory::new(&store, ty);
let mem = Memory::new(&store, ty).unwrap();
assert_eq!(mem.wasmtime_export.memory.offset_guard_size, 0);
match mem.wasmtime_export.memory.style {
wasmtime_environ::MemoryStyle::Dynamic => {}

81
crates/wasmtime/src/store.rs
View File

@@ -1,6 +1,7 @@
use crate::{
module::ModuleRegistry, signatures::SignatureCollection, trampoline::StoreInstanceHandle,
Engine, Func, Module, Trap,
Engine, Func, Module, ResourceLimiter, ResourceLimiterProxy, Trap, DEFAULT_INSTANCE_LIMIT,
DEFAULT_MEMORY_LIMIT, DEFAULT_TABLE_LIMIT,
};
use anyhow::{bail, Result};
use std::any::{Any, TypeId};
@@ -89,6 +90,7 @@ pub(crate) struct StoreInner {
current_poll_cx: Cell<*mut Context<'static>>,
out_of_gas_behavior: Cell<OutOfGas>,
context_values: RefCell<HashMap<TypeId, Box<dyn Any>>>,
limiter: Option<Rc<dyn wasmtime_runtime::ResourceLimiter>>,
}
#[derive(Copy, Clone)]
@@ -120,8 +122,43 @@ impl Hash for HostInfoKey {
}
impl Store {
/// Creates a new store to be associated with the given [`Engine`].
pub fn new(engine: &Engine) -> Store {
/// Creates a new [`Store`] to be associated with the given [`Engine`].
///
/// The created [`Store`] will place no additional limits on the size of linear
/// memories or tables at runtime. Linear memories and tables will be allowed to
/// grow to any upper limit specified in their definitions.
///
/// The store will limit the number of instances, linear memories, and tables created to 10,000.
///
/// Use [`Store::new_with_limits`] with a [`StoreLimitsBuilder`](crate::StoreLimitsBuilder) to
/// specify different limits for the store.
pub fn new(engine: &Engine) -> Self {
Self::new_(engine, None)
}
/// Creates a new [`Store`] to be associated with the given [`Engine`] and using the supplied
/// resource limiter.
///
/// A [`ResourceLimiter`] can be implemented by hosts to control the size of WebAssembly
/// linear memories and tables when a request is made to grow them.
///
/// [`StoreLimitsBuilder`](crate::StoreLimitsBuilder) can be used to create a
/// [`StoreLimits`](crate::StoreLimits) that implements [`ResourceLimiter`] using
/// static limit values.
///
/// # Example
///
/// ```rust
/// # use wasmtime::{Engine, Store, StoreLimitsBuilder};
/// // Place a limit on linear memories so they cannot grow beyond 1 MiB
/// let engine = Engine::default();
/// let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().memory_pages(16).build());
/// ```
pub fn new_with_limits(engine: &Engine, limiter: impl ResourceLimiter + 'static) -> Self {
Self::new_(engine, Some(Rc::new(ResourceLimiterProxy(limiter))))
}
fn new_(engine: &Engine, limiter: Option<Rc<dyn wasmtime_runtime::ResourceLimiter>>) -> Self {
// Ensure that wasmtime_runtime's signal handlers are configured. Note
// that at the `Store` level it means we should perform this
// once-per-thread. Platforms like Unix, however, only require this
@@ -130,7 +167,7 @@ impl Store {
wasmtime_runtime::init_traps(crate::module::GlobalModuleRegistry::is_wasm_pc)
.expect("failed to initialize trap handling");
Store {
Self {
inner: Rc::new(StoreInner {
engine: engine.clone(),
interrupts: Arc::new(Default::default()),
@@ -149,6 +186,7 @@ impl Store {
current_poll_cx: Cell::new(ptr::null_mut()),
out_of_gas_behavior: Cell::new(OutOfGas::Trap),
context_values: RefCell::new(HashMap::new()),
limiter,
}),
}
}
@@ -202,6 +240,10 @@ impl Store {
}
}
pub(crate) fn limiter(&self) -> &Option<Rc<dyn wasmtime_runtime::ResourceLimiter>> {
&self.inner.limiter
}
pub(crate) fn signatures(&self) -> &RefCell<SignatureCollection> {
&self.inner.signatures
}
@@ -231,8 +273,6 @@ impl Store {
}
pub(crate) fn bump_resource_counts(&self, module: &Module) -> Result<()> {
let config = self.engine().config();
fn bump(slot: &Cell<usize>, max: usize, amt: usize, desc: &str) -> Result<()> {
let new = slot.get().saturating_add(amt);
if new > max {
@@ -249,20 +289,11 @@ impl Store {
let module = module.env_module();
let memories = module.memory_plans.len() - module.num_imported_memories;
let tables = module.table_plans.len() - module.num_imported_tables;
let (max_instances, max_memories, max_tables) = self.limits();
bump(
&self.inner.instance_count,
config.max_instances,
1,
"instance",
)?;
bump(
&self.inner.memory_count,
config.max_memories,
memories,
"memory",
)?;
bump(&self.inner.table_count, config.max_tables, tables, "table")?;
bump(&self.inner.instance_count, max_instances, 1, "instance")?;
bump(&self.inner.memory_count, max_memories, memories, "memory")?;
bump(&self.inner.table_count, max_tables, tables, "table")?;
Ok(())
}
@@ -838,6 +869,18 @@ impl Store {
Err(trap) => unsafe { wasmtime_runtime::raise_user_trap(trap.into()) },
}
}
fn limits(&self) -> (usize, usize, usize) {
self.inner
.limiter
.as_ref()
.map(|l| (l.instances(), l.memories(), l.tables()))
.unwrap_or((
DEFAULT_INSTANCE_LIMIT,
DEFAULT_MEMORY_LIMIT,
DEFAULT_TABLE_LIMIT,
))
}
}
unsafe impl TrapInfo for Store {

1
crates/wasmtime/src/trampoline.rs
View File

@@ -78,6 +78,7 @@ fn create_handle(
as *const VMExternRefActivationsTable
as *mut _,
module_info_lookup: Some(store.module_info_lookup()),
limiter: store.limiter().as_ref(),
},
)?;

2
crates/wasmtime/src/trampoline/func.rs
View File

@@ -288,6 +288,7 @@ pub fn create_function(
interrupts: std::ptr::null(),
externref_activations_table: std::ptr::null_mut(),
module_info_lookup: None,
limiter: None,
})?,
trampoline,
))
@@ -320,6 +321,7 @@ pub unsafe fn create_raw_function(
interrupts: std::ptr::null(),
externref_activations_table: std::ptr::null_mut(),
module_info_lookup: None,
limiter: None,
})?,
)
}

4
crates/wasmtime/src/trampoline/memory.rs
View File

@@ -37,6 +37,10 @@ impl RuntimeLinearMemory for LinearMemoryProxy {
self.mem.size()
}
fn maximum(&self) -> Option<u32> {
self.mem.maximum()
}
fn grow(&self, delta: u32) -> Option<u32> {
self.mem.grow(delta)
}

2
crates/wast/src/spectest.rs
View File

@@ -39,7 +39,7 @@ pub fn link_spectest(linker: &mut Linker) -> Result<()> {
linker.define("spectest", "table", table)?;
let ty = MemoryType::new(Limits::new(1, Some(2)));
let memory = Memory::new(linker.store(), ty);
let memory = Memory::new(linker.store(), ty)?;
linker.define("spectest", "memory", memory)?;
Ok(())

2
examples/memory.rs
View File

@@ -75,7 +75,7 @@ fn main() -> Result<()> {
println!("Creating stand-alone memory...");
let memorytype = MemoryType::new(Limits::new(5, Some(5)));
let memory2 = Memory::new(&wasmtime_store, memorytype);
let memory2 = Memory::new(&wasmtime_store, memorytype)?;
assert_eq!(memory2.size(), 5);
assert!(memory2.grow(1).is_err());
assert!(memory2.grow(0).is_ok());

4
tests/all/externals.rs
View File

@@ -67,7 +67,7 @@ fn cross_store() -> anyhow::Result<()> {
let ty = GlobalType::new(ValType::I32, Mutability::Const);
let global = Global::new(&store2, ty, Val::I32(0))?;
let ty = MemoryType::new(Limits::new(1, None));
let memory = Memory::new(&store2, ty);
let memory = Memory::new(&store2, ty)?;
let ty = TableType::new(ValType::FuncRef, Limits::new(1, None));
let table = Table::new(&store2, ty, Val::FuncRef(None))?;
@@ -356,7 +356,7 @@ fn read_write_memory_via_api() {
let cfg = Config::new();
let store = Store::new(&Engine::new(&cfg).unwrap());
let ty = MemoryType::new(Limits::new(1, None));
let mem = Memory::new(&store, ty);
let mem = Memory::new(&store, ty).unwrap();
mem.grow(1).unwrap();
let value = b"hello wasm";

381
tests/all/limits.rs Normal file
View File

@@ -0,0 +1,381 @@
use anyhow::Result;
use std::cell::RefCell;
use std::rc::Rc;
use wasmtime::*;
#[test]
fn test_limits() -> Result<()> {
let engine = Engine::default();
let module = Module::new(
&engine,
r#"(module (memory (export "m") 0) (table (export "t") 0 anyfunc))"#,
)?;
let store = Store::new_with_limits(
&engine,
StoreLimitsBuilder::new()
.memory_pages(10)
.table_elements(5)
.build(),
);
let instance = Instance::new(&store, &module, &[])?;
// Test instance exports and host objects hitting the limit
for memory in std::array::IntoIter::new([
instance.get_memory("m").unwrap(),
Memory::new(&store, MemoryType::new(Limits::new(0, None)))?,
]) {
memory.grow(3)?;
memory.grow(5)?;
memory.grow(2)?;
assert_eq!(
memory.grow(1).map_err(|e| e.to_string()).unwrap_err(),
"failed to grow memory by `1`"
);
}
// Test instance exports and host objects hitting the limit
for table in std::array::IntoIter::new([
instance.get_table("t").unwrap(),
Table::new(
&store,
TableType::new(ValType::FuncRef, Limits::new(0, None)),
Val::FuncRef(None),
)?,
]) {
table.grow(2, Val::FuncRef(None))?;
table.grow(1, Val::FuncRef(None))?;
table.grow(2, Val::FuncRef(None))?;
assert_eq!(
table
.grow(1, Val::FuncRef(None))
.map_err(|e| e.to_string())
.unwrap_err(),
"failed to grow table by `1`"
);
}
Ok(())
}
#[test]
fn test_limits_memory_only() -> Result<()> {
let engine = Engine::default();
let module = Module::new(
&engine,
r#"(module (memory (export "m") 0) (table (export "t") 0 anyfunc))"#,
)?;
let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().memory_pages(10).build());
let instance = Instance::new(&store, &module, &[])?;
// Test instance exports and host objects hitting the limit
for memory in std::array::IntoIter::new([
instance.get_memory("m").unwrap(),
Memory::new(&store, MemoryType::new(Limits::new(0, None)))?,
]) {
memory.grow(3)?;
memory.grow(5)?;
memory.grow(2)?;
assert_eq!(
memory.grow(1).map_err(|e| e.to_string()).unwrap_err(),
"failed to grow memory by `1`"
);
}
// Test instance exports and host objects *not* hitting the limit
for table in std::array::IntoIter::new([
instance.get_table("t").unwrap(),
Table::new(
&store,
TableType::new(ValType::FuncRef, Limits::new(0, None)),
Val::FuncRef(None),
)?,
]) {
table.grow(2, Val::FuncRef(None))?;
table.grow(1, Val::FuncRef(None))?;
table.grow(2, Val::FuncRef(None))?;
table.grow(1, Val::FuncRef(None))?;
}
Ok(())
}
#[test]
fn test_initial_memory_limits_exceeded() -> Result<()> {
let engine = Engine::default();
let module = Module::new(&engine, r#"(module (memory (export "m") 11))"#)?;
let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().memory_pages(10).build());
match Instance::new(&store, &module, &[]) {
Ok(_) => unreachable!(),
Err(e) => assert_eq!(
e.to_string(),
"Insufficient resources: memory minimum size of 11 pages exceeds memory limits"
),
}
match Memory::new(&store, MemoryType::new(Limits::new(25, None))) {
Ok(_) => unreachable!(),
Err(e) => assert_eq!(
e.to_string(),
"Insufficient resources: memory minimum size of 25 pages exceeds memory limits"
),
}
Ok(())
}
#[test]
fn test_limits_table_only() -> Result<()> {
let engine = Engine::default();
let module = Module::new(
&engine,
r#"(module (memory (export "m") 0) (table (export "t") 0 anyfunc))"#,
)?;
let store =
Store::new_with_limits(&engine, StoreLimitsBuilder::new().table_elements(5).build());
let instance = Instance::new(&store, &module, &[])?;
// Test instance exports and host objects *not* hitting the limit
for memory in std::array::IntoIter::new([
instance.get_memory("m").unwrap(),
Memory::new(&store, MemoryType::new(Limits::new(0, None)))?,
]) {
memory.grow(3)?;
memory.grow(5)?;
memory.grow(2)?;
memory.grow(1)?;
}
// Test instance exports and host objects hitting the limit
for table in std::array::IntoIter::new([
instance.get_table("t").unwrap(),
Table::new(
&store,
TableType::new(ValType::FuncRef, Limits::new(0, None)),
Val::FuncRef(None),
)?,
]) {
table.grow(2, Val::FuncRef(None))?;
table.grow(1, Val::FuncRef(None))?;
table.grow(2, Val::FuncRef(None))?;
assert_eq!(
table
.grow(1, Val::FuncRef(None))
.map_err(|e| e.to_string())
.unwrap_err(),
"failed to grow table by `1`"
);
}
Ok(())
}
#[test]
fn test_initial_table_limits_exceeded() -> Result<()> {
let engine = Engine::default();
let module = Module::new(&engine, r#"(module (table (export "t") 23 anyfunc))"#)?;
let store =
Store::new_with_limits(&engine, StoreLimitsBuilder::new().table_elements(4).build());
match Instance::new(&store, &module, &[]) {
Ok(_) => unreachable!(),
Err(e) => assert_eq!(
e.to_string(),
"Insufficient resources: table minimum size of 23 elements exceeds table limits"
),
}
match Table::new(
&store,
TableType::new(ValType::FuncRef, Limits::new(99, None)),
Val::FuncRef(None),
) {
Ok(_) => unreachable!(),
Err(e) => assert_eq!(
e.to_string(),
"Insufficient resources: table minimum size of 99 elements exceeds table limits"
),
}
Ok(())
}
#[test]
fn test_pooling_allocator_initial_limits_exceeded() -> Result<()> {
let mut config = Config::new();
config.wasm_multi_memory(true);
config.allocation_strategy(InstanceAllocationStrategy::Pooling {
strategy: PoolingAllocationStrategy::NextAvailable,
module_limits: ModuleLimits {
memories: 2,
..Default::default()
},
instance_limits: InstanceLimits {
count: 1,
..Default::default()
},
});
let engine = Engine::new(&config)?;
let module = Module::new(
&engine,
r#"(module (memory (export "m1") 2) (memory (export "m2") 5))"#,
)?;
let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().memory_pages(3).build());
match Instance::new(&store, &module, &[]) {
Ok(_) => unreachable!(),
Err(e) => assert_eq!(
e.to_string(),
"Insufficient resources: memory minimum size of 5 pages exceeds memory limits"
),
}
// An instance should still be able to be created after the failure above
let module = Module::new(&engine, r#"(module (memory (export "m") 2))"#)?;
Instance::new(&store, &module, &[])?;
Ok(())
}
struct MemoryContext {
host_memory_used: usize,
wasm_memory_used: usize,
memory_limit: usize,
limit_exceeded: bool,
limiter_dropped: bool,
}
struct HostMemoryLimiter(Rc<RefCell<MemoryContext>>);
impl ResourceLimiter for HostMemoryLimiter {
fn memory_growing(&self, current: u32, desired: u32, maximum: Option<u32>) -> bool {
let mut ctx = self.0.borrow_mut();
// Check if the desired exceeds a maximum (either from Wasm or from the host)
if desired > maximum.unwrap_or(u32::MAX) {
ctx.limit_exceeded = true;
return false;
}
assert_eq!(current as usize * 0x10000, ctx.wasm_memory_used);
let desired = desired as usize * 0x10000;
if desired + ctx.host_memory_used > ctx.memory_limit {
ctx.limit_exceeded = true;
return false;
}
ctx.wasm_memory_used = desired;
true
}
fn table_growing(&self, _current: u32, _desired: u32, _maximum: Option<u32>) -> bool {
true
}
}
impl Drop for HostMemoryLimiter {
fn drop(&mut self) {
self.0.borrow_mut().limiter_dropped = true;
}
}
#[test]
fn test_custom_limiter() -> Result<()> {
let mut config = Config::default();
// This approximates a function that would "allocate" resources that the host tracks.
// Here this is a simple function that increments the current host memory "used".
config.wrap_host_func("", "alloc", |caller: Caller, size: u32| -> u32 {
if let Some(ctx) = caller.store().get::<Rc<RefCell<MemoryContext>>>() {
let mut ctx = ctx.borrow_mut();
let size = size as usize;
if size + ctx.host_memory_used + ctx.wasm_memory_used <= ctx.memory_limit {
ctx.host_memory_used += size;
return 1;
}
ctx.limit_exceeded = true;
}
0
});
let engine = Engine::new(&config)?;
let module = Module::new(
&engine,
r#"(module (import "" "alloc" (func $alloc (param i32) (result i32))) (memory (export "m") 0) (func (export "f") (param i32) (result i32) local.get 0 call $alloc))"#,
)?;
let context = Rc::new(RefCell::new(MemoryContext {
host_memory_used: 0,
wasm_memory_used: 0,
memory_limit: 1 << 20, // 16 wasm pages is the limit for both wasm + host memory
limit_exceeded: false,
limiter_dropped: false,
}));
let store = Store::new_with_limits(&engine, HostMemoryLimiter(context.clone()));
assert!(store.set(context.clone()).is_ok());
let linker = Linker::new(&store);
let instance = linker.instantiate(&module)?;
let memory = instance.get_memory("m").unwrap();
// Grow the memory by 640 KiB
memory.grow(3)?;
memory.grow(5)?;
memory.grow(2)?;
assert!(!context.borrow().limit_exceeded);
// Grow the host "memory" by 384 KiB
let f = instance.get_typed_func::<u32, u32>("f")?;
assert_eq!(f.call(1 * 0x10000).unwrap(), 1);
assert_eq!(f.call(3 * 0x10000).unwrap(), 1);
assert_eq!(f.call(2 * 0x10000).unwrap(), 1);
// Memory is at the maximum, but the limit hasn't been exceeded
assert!(!context.borrow().limit_exceeded);
// Try to grow the memory again
assert_eq!(
memory.grow(1).map_err(|e| e.to_string()).unwrap_err(),
"failed to grow memory by `1`"
);
assert!(context.borrow().limit_exceeded);
// Try to grow the host "memory" again
assert_eq!(f.call(1).unwrap(), 0);
assert!(context.borrow().limit_exceeded);
drop(f);
drop(memory);
drop(instance);
drop(linker);
drop(store);
assert!(context.borrow().limiter_dropped);
Ok(())
}

4
tests/all/linker.rs
View File

@@ -51,11 +51,11 @@ fn link_twice_bad() -> Result<()> {
// memories
let ty = MemoryType::new(Limits::new(1, None));
let memory = Memory::new(&store, ty);
let memory = Memory::new(&store, ty)?;
linker.define("m", "", memory.clone())?;
assert!(linker.define("m", "", memory.clone()).is_err());
let ty = MemoryType::new(Limits::new(2, None));
let memory = Memory::new(&store, ty);
let memory = Memory::new(&store, ty)?;
assert!(linker.define("m", "", memory.clone()).is_err());
// tables

1
tests/all/main.rs
View File

@@ -13,6 +13,7 @@ mod import_calling_export;
mod import_indexes;
mod instance;
mod invoke_func_via_table;
mod limits;
mod linker;
mod memory_creator;
mod module;

11
tests/all/memory_creator.rs
View File

@@ -17,6 +17,7 @@ mod not_for_windows {
struct CustomMemory {
mem: *mut c_void,
size: usize,
guard_size: usize,
used_wasm_pages: RefCell<u32>,
glob_page_counter: Arc<Mutex<u64>>,
}
@@ -43,6 +44,7 @@ mod not_for_windows {
Self {
mem,
size,
guard_size,
used_wasm_pages: RefCell::new(num_wasm_pages),
glob_page_counter: glob_counter,
}
@@ -63,6 +65,10 @@ mod not_for_windows {
*self.used_wasm_pages.borrow()
}
fn maximum(&self) -> Option<u32> {
Some((self.size as u32 - self.guard_size as u32) / WASM_PAGE_SIZE)
}
fn grow(&self, delta: u32) -> Option<u32> {
let delta_size = (delta as usize).checked_mul(WASM_PAGE_SIZE as usize)?;
@@ -70,11 +76,8 @@ mod not_for_windows {
let prev_size = (prev_pages as usize).checked_mul(WASM_PAGE_SIZE as usize)?;
let new_pages = prev_pages.checked_add(delta)?;
let new_size = (new_pages as usize).checked_mul(WASM_PAGE_SIZE as usize)?;
let guard_size = unsafe { sysconf(_SC_PAGESIZE) as usize };
if new_size > self.size - guard_size {
if new_pages > self.maximum().unwrap() {
return None;
}
unsafe {

9
tests/all/module_linking.rs
View File

@@ -190,7 +190,6 @@ fn imports_exports() -> Result<()> {
fn limit_instances() -> Result<()> {
let mut config = Config::new();
config.wasm_module_linking(true);
config.max_instances(10);
let engine = Engine::new(&config)?;
let module = Module::new(
&engine,
@@ -216,7 +215,7 @@ fn limit_instances() -> Result<()> {
)
"#,
)?;
let store = Store::new(&engine);
let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().instances(10).build());
let err = Instance::new(&store, &module, &[]).err().unwrap();
assert!(
err.to_string().contains("resource limit exceeded"),
@@ -231,7 +230,6 @@ fn limit_memories() -> Result<()> {
let mut config = Config::new();
config.wasm_module_linking(true);
config.wasm_multi_memory(true);
config.max_memories(10);
let engine = Engine::new(&config)?;
let module = Module::new(
&engine,
@@ -252,7 +250,7 @@ fn limit_memories() -> Result<()> {
)
"#,
)?;
let store = Store::new(&engine);
let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().memories(10).build());
let err = Instance::new(&store, &module, &[]).err().unwrap();
assert!(
err.to_string().contains("resource limit exceeded"),
@@ -266,7 +264,6 @@ fn limit_memories() -> Result<()> {
fn limit_tables() -> Result<()> {
let mut config = Config::new();
config.wasm_module_linking(true);
config.max_tables(10);
let engine = Engine::new(&config)?;
let module = Module::new(
&engine,
@@ -287,7 +284,7 @@ fn limit_tables() -> Result<()> {
)
"#,
)?;
let store = Store::new(&engine);
let store = Store::new_with_limits(&engine, StoreLimitsBuilder::new().tables(10).build());
let err = Instance::new(&store, &module, &[]).err().unwrap();
assert!(
err.to_string().contains("resource limit exceeded"),