// This file is part of Substrate.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
use crate::{error::WasmError, wasm_runtime::HeapAllocStrategy};
use polkavm::ArcBytes;
use wasm_instrument::parity_wasm::elements::{
deserialize_buffer, serialize, ExportEntry, External, Internal, MemorySection, MemoryType,
Module, Section,
};
/// A program blob containing a Substrate runtime.
#[derive(Clone)]
pub struct RuntimeBlob(BlobKind);
#[derive(Clone)]
enum BlobKind {
WebAssembly(Module),
PolkaVM((polkavm::ProgramBlob, ArcBytes)),
}
impl RuntimeBlob {
/// Create `RuntimeBlob` from the given WASM or PolkaVM compressed program blob.
///
/// See [`sp_maybe_compressed_blob`] for details about decompression.
pub fn uncompress_if_needed(wasm_code: &[u8]) -> Result<Self, WasmError> {
use sp_maybe_compressed_blob::CODE_BLOB_BOMB_LIMIT;
let wasm_code = sp_maybe_compressed_blob::decompress(wasm_code, CODE_BLOB_BOMB_LIMIT)
.map_err(|e| WasmError::Other(format!("Decompression error: {:?}", e)))?;
Self::new(&wasm_code)
}
/// Create `RuntimeBlob` from the given WASM or PolkaVM program blob.
///
/// Returns `Err` if the blob cannot be deserialized.
///
/// Will only accept a PolkaVM program if the `SUBSTRATE_ENABLE_POLKAVM` environment
/// variable is set to `1`.
pub fn new(raw_blob: &[u8]) -> Result<Self, WasmError> {
if raw_blob.starts_with(b"PVM\0") {
if crate::is_polkavm_enabled() {
let raw = ArcBytes::from(raw_blob);
let blob = polkavm::ProgramBlob::parse(raw.clone())?;
return Ok(Self(BlobKind::PolkaVM((blob, raw))));
} else {
return Err(WasmError::Other("expected a WASM runtime blob, found a PolkaVM runtime blob; set the 'SUBSTRATE_ENABLE_POLKAVM' environment variable to enable the experimental PolkaVM-based executor".to_string()));
}
}
let raw_module: Module = deserialize_buffer(raw_blob)
.map_err(|e| WasmError::Other(format!("cannot deserialize module: {:?}", e)))?;
Ok(Self(BlobKind::WebAssembly(raw_module)))
}
/// Run a pass that instrument this module so as to introduce a deterministic stack height
/// limit.
///
/// It will introduce a global mutable counter. The instrumentation will increase the counter
/// according to the "cost" of the callee. If the cost exceeds the `stack_depth_limit` constant,
/// the instrumentation will trap. The counter will be decreased as soon as the the callee
/// returns.
///
/// The stack cost of a function is computed based on how much locals there are and the maximum
/// depth of the wasm operand stack.
///
/// Only valid for WASM programs; will return an error if the blob is a PolkaVM program.
pub fn inject_stack_depth_metering(self, stack_depth_limit: u32) -> Result<Self, WasmError> {
let injected_module =
wasm_instrument::inject_stack_limiter(self.into_webassembly_blob()?, stack_depth_limit)
.map_err(|e| {
WasmError::Other(format!("cannot inject the stack limiter: {:?}", e))
})?;
Ok(Self(BlobKind::WebAssembly(injected_module)))
}
/// Converts a WASM memory import into a memory section and exports it.
///
/// Does nothing if there's no memory import.
///
/// May return an error in case the WASM module is invalid.
///
/// Only valid for WASM programs; will return an error if the blob is a PolkaVM program.
pub fn convert_memory_import_into_export(&mut self) -> Result<(), WasmError> {
let raw_module = self.as_webassembly_blob_mut()?;
let import_section = match raw_module.import_section_mut() {
Some(import_section) => import_section,
None => return Ok(()),
};
let import_entries = import_section.entries_mut();
for index in 0..import_entries.len() {
let entry = &import_entries[index];
let memory_ty = match entry.external() {
External::Memory(memory_ty) => *memory_ty,
_ => continue,
};
let memory_name = entry.field().to_owned();
import_entries.remove(index);
raw_module
.insert_section(Section::Memory(MemorySection::with_entries(vec![memory_ty])))
.map_err(|error| {
WasmError::Other(format!(
"can't convert a memory import into an export: failed to insert a new memory section: {}",
error
))
})?;
if raw_module.export_section_mut().is_none() {
// A module without an export section is somewhat unrealistic, but let's do this
// just in case to cover all of our bases.
raw_module
.insert_section(Section::Export(Default::default()))
.expect("an export section can be always inserted if it doesn't exist; qed");
}
raw_module
.export_section_mut()
.expect("export section already existed or we just added it above, so it always exists; qed")
.entries_mut()
.push(ExportEntry::new(memory_name, Internal::Memory(0)));
break
}
Ok(())
}
/// Modifies the blob's memory section according to the given `heap_alloc_strategy`.
///
/// Will return an error in case there is no memory section present,
/// or if the memory section is empty.
///
/// Only valid for WASM programs; will return an error if the blob is a PolkaVM program.
pub fn setup_memory_according_to_heap_alloc_strategy(
&mut self,
heap_alloc_strategy: HeapAllocStrategy,
) -> Result<(), WasmError> {
let raw_module = self.as_webassembly_blob_mut()?;
let memory_section = raw_module
.memory_section_mut()
.ok_or_else(|| WasmError::Other("no memory section found".into()))?;
if memory_section.entries().is_empty() {
return Err(WasmError::Other("memory section is empty".into()))
}
for memory_ty in memory_section.entries_mut() {
let initial = memory_ty.limits().initial();
let (min, max) = match heap_alloc_strategy {
HeapAllocStrategy::Dynamic { maximum_pages } => {
// Ensure `initial <= maximum_pages`
(maximum_pages.map(|m| m.min(initial)).unwrap_or(initial), maximum_pages)
},
HeapAllocStrategy::Static { extra_pages } => {
let pages = initial.saturating_add(extra_pages);
(pages, Some(pages))
},
};
*memory_ty = MemoryType::new(min, max);
}
Ok(())
}
/// Scans the wasm blob for the first section with the name that matches the given. Returns the
/// contents of the custom section if found or `None` otherwise.
///
/// Only valid for WASM programs; will return an error if the blob is a PolkaVM program.
pub fn custom_section_contents(&self, section_name: &str) -> Option<&[u8]> {
self.as_webassembly_blob()
.ok()?
.custom_sections()
.find(|cs| cs.name() == section_name)
.map(|cs| cs.payload())
}
/// Consumes this runtime blob and serializes it.
pub fn serialize(self) -> Vec<u8> {
match self.0 {
BlobKind::WebAssembly(raw_module) =>
serialize(raw_module).expect("serializing into a vec should succeed; qed"),
BlobKind::PolkaVM(ref blob) => blob.1.to_vec(),
}
}
fn as_webassembly_blob(&self) -> Result<&Module, WasmError> {
match self.0 {
BlobKind::WebAssembly(ref raw_module) => Ok(raw_module),
BlobKind::PolkaVM(..) => Err(WasmError::Other(
"expected a WebAssembly program; found a PolkaVM program blob".into(),
)),
}
}
fn as_webassembly_blob_mut(&mut self) -> Result<&mut Module, WasmError> {
match self.0 {
BlobKind::WebAssembly(ref mut raw_module) => Ok(raw_module),
BlobKind::PolkaVM(..) => Err(WasmError::Other(
"expected a WebAssembly program; found a PolkaVM program blob".into(),
)),
}
}
fn into_webassembly_blob(self) -> Result<Module, WasmError> {
match self.0 {
BlobKind::WebAssembly(raw_module) => Ok(raw_module),
BlobKind::PolkaVM(..) => Err(WasmError::Other(
"expected a WebAssembly program; found a PolkaVM program blob".into(),
)),
}
}
/// Gets a reference to the inner PolkaVM program blob, if this is a PolkaVM program.
pub fn as_polkavm_blob(&self) -> Option<&polkavm::ProgramBlob> {
match self.0 {
BlobKind::WebAssembly(..) => None,
BlobKind::PolkaVM((ref blob, _)) => Some(blob),
}
}
}