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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/dom/JSValidatorChild.h"
#include "mozilla/dom/JSOracleChild.h"
#include "mozilla/Encoding.h"
#include "mozilla/dom/ScriptDecoding.h"
#include "mozilla/ipc/Endpoint.h"
#include "js/CompileOptions.h"
#include "js/JSON.h"
#include "js/SourceText.h"
#include "js/experimental/CompileScript.h"
#include "js/experimental/JSStencil.h"
#include "xpcpublic.h"
using namespace mozilla::dom;
using Encoding = mozilla::Encoding;
mozilla::UniquePtr<mozilla::Decoder> TryGetDecoder(
const mozilla::Span<const uint8_t>& aSourceBytes,
const nsACString& aContentCharset, const nsAString& aHintCharset,
const nsAString& aDocumentCharset) {
const Encoding* encoding;
mozilla::UniquePtr<mozilla::Decoder> unicodeDecoder;
std::tie(encoding, std::ignore) = Encoding::ForBOM(aSourceBytes);
if (encoding) {
unicodeDecoder = encoding->NewDecoderWithBOMRemoval();
}
if (!unicodeDecoder) {
encoding = Encoding::ForLabel(aContentCharset);
if (encoding) {
unicodeDecoder = encoding->NewDecoderWithoutBOMHandling();
}
if (!unicodeDecoder) {
encoding = Encoding::ForLabel(aHintCharset);
if (encoding) {
unicodeDecoder = encoding->NewDecoderWithoutBOMHandling();
}
}
if (!unicodeDecoder) {
encoding = Encoding::ForLabel(aDocumentCharset);
if (encoding) {
unicodeDecoder = encoding->NewDecoderWithoutBOMHandling();
}
}
}
if (!unicodeDecoder && !IsUtf8(mozilla::Span(reinterpret_cast<const char*>(
aSourceBytes.Elements()),
aSourceBytes.Length()))) {
// Curiously, there are various callers that don't pass aDocument. The
// fallback in the old code was ISO-8859-1, which behaved like
// windows-1252.
unicodeDecoder = WINDOWS_1252_ENCODING->NewDecoderWithoutBOMHandling();
}
return unicodeDecoder;
}
mozilla::ipc::IPCResult JSValidatorChild::RecvIsOpaqueResponseAllowed(
IsOpaqueResponseAllowedResolver&& aResolver) {
mResolver.emplace(aResolver);
return IPC_OK();
}
mozilla::ipc::IPCResult JSValidatorChild::RecvOnDataAvailable(Shmem&& aData) {
if (!mResolver) {
MOZ_ASSERT(!CanSend());
return IPC_OK();
}
if (!mSourceBytes.Append(Span(aData.get<char>(), aData.Size<char>()),
mozilla::fallible)) {
// To prevent an attacker from flood the validation process,
// we don't validate here.
Resolve(ValidatorResult::Failure);
}
DeallocShmem(aData);
return IPC_OK();
}
mozilla::ipc::IPCResult JSValidatorChild::RecvOnStopRequest(
const nsresult& aReason, const nsACString& aContentCharset,
const nsAString& aHintCharset, const nsAString& aDocumentCharset) {
if (!mResolver) {
return IPC_OK();
}
if (NS_FAILED(aReason)) {
Resolve(ValidatorResult::Failure);
} else if (mSourceBytes.IsEmpty()) {
// The empty document parses as JavaScript.
Resolve(ValidatorResult::JavaScript);
} else {
UniquePtr<Decoder> unicodeDecoder = TryGetDecoder(
mSourceBytes, aContentCharset, aHintCharset, aDocumentCharset);
if (!unicodeDecoder) {
Resolve(ShouldAllowJS(mSourceBytes));
} else {
BufferUniquePtr<Utf8Unit[]> buffer;
auto result = GetUTF8EncodedContent(mSourceBytes, buffer, unicodeDecoder);
if (result.isErr()) {
Resolve(ValidatorResult::Failure);
} else {
Resolve(ShouldAllowJS(result.unwrap()));
}
}
}
return IPC_OK();
}
void JSValidatorChild::ActorDestroy(ActorDestroyReason aReason) {
if (mResolver) {
Resolve(ValidatorResult::Failure);
}
};
void JSValidatorChild::Resolve(ValidatorResult aResult) {
MOZ_ASSERT(mResolver);
Maybe<Shmem> data = Nothing();
if (aResult == ValidatorResult::JavaScript && !mSourceBytes.IsEmpty()) {
Shmem sharedData;
nsresult rv =
JSValidatorUtils::CopyCStringToShmem(this, mSourceBytes, sharedData);
if (NS_SUCCEEDED(rv)) {
data = Some(std::move(sharedData));
}
}
mResolver.ref()(std::tuple<mozilla::Maybe<Shmem>&&, const ValidatorResult&>(
std::move(data), aResult));
mResolver.reset();
}
mozilla::Result<mozilla::Span<const char>, nsresult>
JSValidatorChild::GetUTF8EncodedContent(
const mozilla::Span<const uint8_t>& aData,
BufferUniquePtr<Utf8Unit[]>& aBuffer, UniquePtr<Decoder>& aDecoder) {
MOZ_ASSERT(aDecoder);
// We need the output buffer to be UTF8
CheckedInt<size_t> bufferLength =
ScriptDecoding<Utf8Unit>::MaxBufferLength(aDecoder, aData.Length());
if (!bufferLength.isValid()) {
return mozilla::Err(NS_ERROR_FAILURE);
}
CheckedInt<size_t> bufferByteSize = bufferLength * sizeof(Utf8Unit);
if (!bufferByteSize.isValid()) {
return mozilla::Err(NS_ERROR_FAILURE);
}
aBuffer.reset(static_cast<Utf8Unit*>(js_malloc(bufferByteSize.value())));
if (!aBuffer) {
return mozilla::Err(NS_ERROR_FAILURE);
}
size_t written = ScriptDecoding<Utf8Unit>::DecodeInto(
aDecoder, aData, Span(aBuffer.get(), bufferLength.value()),
/* aEndOfSource = */ true);
MOZ_ASSERT(written <= bufferLength.value());
MOZ_ASSERT(
IsUtf8(Span(reinterpret_cast<const char*>(aBuffer.get()), written)));
return Span(reinterpret_cast<const char*>(aBuffer.get()), written);
}
JSValidatorChild::ValidatorResult JSValidatorChild::ShouldAllowJS(
const mozilla::Span<const char>& aSpan) const {
// It's possible that the data we get is not valid UTF-8, so aSpan
// ends empty here. We should treat it as a failure because this
// is not valid JS.
if (aSpan.IsEmpty()) {
return ValidatorResult::Failure;
}
MOZ_DIAGNOSTIC_ASSERT(IsUtf8(aSpan));
JS::FrontendContext* fc = JSOracleChild::JSFrontendContext();
if (!fc) {
return ValidatorResult::Failure;
}
JS::SourceText<Utf8Unit> srcBuf;
if (!srcBuf.init(fc, aSpan.Elements(), aSpan.Length(),
JS::SourceOwnership::Borrowed)) {
JS::ClearFrontendErrors(fc);
return ValidatorResult::Failure;
}
// Parse to JavaScript
JS::PrefableCompileOptions prefableOptions;
xpc::SetPrefableCompileOptions(prefableOptions);
// For the syntax validation purpose, asm.js doesn't need to be enabled.
prefableOptions.setAsmJSOption(JS::AsmJSOption::DisabledByAsmJSPref);
JS::CompileOptions options(prefableOptions);
RefPtr<JS::Stencil> stencil =
JS::CompileGlobalScriptToStencil(fc, options, srcBuf);
if (!stencil) {
JS::ClearFrontendErrors(fc);
return ValidatorResult::Other;
}
MOZ_ASSERT(!aSpan.IsEmpty());
// Parse to JSON
if (IsAscii(aSpan)) {
// Ascii is a subset of Latin1, and JS_ParseJSON can take Latin1 directly
if (JS::IsValidJSON(
reinterpret_cast<const JS::Latin1Char*>(aSpan.Elements()),
aSpan.Length())) {
return ValidatorResult::JSON;
}
} else {
nsString decoded;
nsresult rv = UTF_8_ENCODING->DecodeWithBOMRemoval(
Span(reinterpret_cast<const uint8_t*>(aSpan.Elements()),
aSpan.Length()),
decoded);
if (NS_FAILED(rv)) {
return ValidatorResult::Failure;
}
if (JS::IsValidJSON(decoded.BeginReading(), decoded.Length())) {
return ValidatorResult::JSON;
}
}
// Since the JSON parsing failed, we confirmed the file is Javascript and not
// JSON.
return ValidatorResult::JavaScript;
}
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