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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 https://mozilla.org/MPL/2.0/. */
#define MOZ_USE_LAUNCHER_ERROR
#include "nsWindowsDllInterceptor.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Attributes.h"
#include "mozilla/BinarySearch.h"
#include "mozilla/ImportDir.h"
#include "mozilla/NativeNt.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/Types.h"
#include "mozilla/WindowsDllBlocklist.h"
#include "mozilla/WinHeaderOnlyUtils.h"
#include "DllBlocklistInit.h"
#include "freestanding/DllBlocklist.h"
#include "freestanding/SharedSection.h"
namespace mozilla {
#if defined(MOZ_ASAN) || defined(_M_ARM64)
// This DLL blocking code is incompatible with ASAN because
// it is able to execute before ASAN itself has even initialized.
// Also, AArch64 has not been tested with this.
LauncherVoidResultWithLineInfo InitializeDllBlocklistOOP(
const wchar_t* aFullImagePath, HANDLE aChildProcess,
const IMAGE_THUNK_DATA*) {
return mozilla::Ok();
}
LauncherVoidResultWithLineInfo InitializeDllBlocklistOOPFromLauncher(
const wchar_t* aFullImagePath, HANDLE aChildProcess) {
return mozilla::Ok();
}
#else
static LauncherVoidResultWithLineInfo InitializeDllBlocklistOOPInternal(
const wchar_t* aFullImagePath, nt::CrossExecTransferManager& aTransferMgr,
const IMAGE_THUNK_DATA* aCachedNtdllThunk) {
CrossProcessDllInterceptor intcpt(aTransferMgr.RemoteProcess());
intcpt.Init(L"ntdll.dll");
bool ok = freestanding::stub_NtMapViewOfSection.SetDetour(
aTransferMgr, intcpt, "NtMapViewOfSection",
&freestanding::patched_NtMapViewOfSection);
if (!ok) {
return LAUNCHER_ERROR_FROM_DETOUR_ERROR(intcpt.GetLastDetourError());
}
ok = freestanding::stub_LdrLoadDll.SetDetour(
aTransferMgr, intcpt, "LdrLoadDll", &freestanding::patched_LdrLoadDll);
if (!ok) {
return LAUNCHER_ERROR_FROM_DETOUR_ERROR(intcpt.GetLastDetourError());
}
// Because aChildProcess has just been created in a suspended state, its
// dynamic linker has not yet been initialized, thus its executable has
// not yet been linked with ntdll.dll. If the blocklist hook intercepts a
// library load prior to the link, the hook will be unable to invoke any
// ntdll.dll functions.
//
// We know that the executable for our *current* process's binary is already
// linked into ntdll, so we obtain the IAT from our own executable and graft
// it onto the child process's IAT, thus enabling the child process's hook to
// safely make its ntdll calls.
const nt::PEHeaders& ourExeImage = aTransferMgr.LocalPEHeaders();
// As part of our mitigation of binary tampering, copy our import directory
// from the original in our executable file.
LauncherVoidResult importDirRestored =
RestoreImportDirectory(aFullImagePath, aTransferMgr);
if (importDirRestored.isErr()) {
return importDirRestored;
}
mozilla::nt::PEHeaders ntdllImage(::GetModuleHandleW(L"ntdll.dll"));
if (!ntdllImage) {
return LAUNCHER_ERROR_FROM_WIN32(ERROR_BAD_EXE_FORMAT);
}
// If we have a cached IAT i.e. |aCachedNtdllThunk| is non-null, we can
// safely copy it to |aChildProcess| even if the local IAT has been modified.
// If |aCachedNtdllThunk| is null, we've failed to cache the IAT or we're in
// the launcher process where there is no chance to cache the IAT. In those
// cases, we retrieve the IAT with the boundary check to avoid a modified IAT
// from being copied into |aChildProcess|.
Maybe<Span<IMAGE_THUNK_DATA> > ntdllThunks;
if (aCachedNtdllThunk) {
ntdllThunks = ourExeImage.GetIATThunksForModule("ntdll.dll");
} else {
Maybe<Range<const uint8_t> > ntdllBoundaries = ntdllImage.GetBounds();
if (!ntdllBoundaries) {
return LAUNCHER_ERROR_FROM_WIN32(ERROR_BAD_EXE_FORMAT);
}
// We can use GetIATThunksForModule() to check whether IAT is modified
// or not because no functions exported from ntdll.dll is forwarded.
ntdllThunks =
ourExeImage.GetIATThunksForModule("ntdll.dll", ntdllBoundaries.ptr());
}
if (!ntdllThunks) {
return LAUNCHER_ERROR_FROM_WIN32(ERROR_INVALID_DATA);
}
{ // Scope for prot
PIMAGE_THUNK_DATA firstIatThunkDst = ntdllThunks.value().data();
const IMAGE_THUNK_DATA* firstIatThunkSrc =
aCachedNtdllThunk ? aCachedNtdllThunk : firstIatThunkDst;
SIZE_T iatLength = ntdllThunks.value().LengthBytes();
AutoVirtualProtect prot =
aTransferMgr.Protect(firstIatThunkDst, iatLength, PAGE_READWRITE);
if (!prot) {
return LAUNCHER_ERROR_FROM_MOZ_WINDOWS_ERROR(prot.GetError());
}
LauncherVoidResult writeResult =
aTransferMgr.Transfer(firstIatThunkDst, firstIatThunkSrc, iatLength);
if (writeResult.isErr()) {
return writeResult.propagateErr();
}
}
// Tell the mozglue blocklist that we have bootstrapped
uint32_t newFlags = eDllBlocklistInitFlagWasBootstrapped;
if (gBlocklistInitFlags & eDllBlocklistInitFlagWasBootstrapped) {
// If we ourselves were bootstrapped, then we are starting a child process
// and need to set the appropriate flag.
newFlags |= eDllBlocklistInitFlagIsChildProcess;
}
LauncherVoidResult writeResult =
aTransferMgr.Transfer(&gBlocklistInitFlags, &newFlags, sizeof(newFlags));
if (writeResult.isErr()) {
return writeResult.propagateErr();
}
return Ok();
}
LauncherVoidResultWithLineInfo InitializeDllBlocklistOOP(
const wchar_t* aFullImagePath, HANDLE aChildProcess,
const IMAGE_THUNK_DATA* aCachedNtdllThunk) {
nt::CrossExecTransferManager transferMgr(aChildProcess);
if (!transferMgr) {
return LAUNCHER_ERROR_FROM_WIN32(ERROR_BAD_EXE_FORMAT);
}
// We come here when the browser process launches a sandbox process.
// If the launcher process already failed to bootstrap the browser process,
// we should not attempt to bootstrap a child process because it's likely
// to fail again. Instead, we only restore the import directory entry.
if (!(gBlocklistInitFlags & eDllBlocklistInitFlagWasBootstrapped)) {
return RestoreImportDirectory(aFullImagePath, transferMgr);
}
// Transfer a readonly handle to the child processes because all information
// are already written to the section by the launcher and main process.
LauncherVoidResult transferResult =
freestanding::gSharedSection.TransferHandle(transferMgr, GENERIC_READ);
if (transferResult.isErr()) {
return transferResult.propagateErr();
}
return InitializeDllBlocklistOOPInternal(aFullImagePath, transferMgr,
aCachedNtdllThunk);
}
LauncherVoidResultWithLineInfo InitializeDllBlocklistOOPFromLauncher(
const wchar_t* aFullImagePath, HANDLE aChildProcess) {
nt::CrossExecTransferManager transferMgr(aChildProcess);
if (!transferMgr) {
return LAUNCHER_ERROR_FROM_WIN32(ERROR_BAD_EXE_FORMAT);
}
// The launcher process initializes a section object, whose handle is
// transferred to the browser process, and that transferred handle in
// the browser process is transferred to the sandbox processes.
LauncherVoidResultWithLineInfo result =
freestanding::gSharedSection.Init(transferMgr.LocalPEHeaders());
if (result.isErr()) {
return result.propagateErr();
}
// Transfer a writable handle to the main process because it needs to append
// dependent module paths to the section.
LauncherVoidResult transferResult =
freestanding::gSharedSection.TransferHandle(transferMgr,
GENERIC_READ | GENERIC_WRITE);
if (transferResult.isErr()) {
return transferResult.propagateErr();
}
auto clearInstance = MakeScopeExit([]() {
// After transfer, the launcher process does not need the object anymore.
freestanding::gSharedSection.Reset(nullptr);
});
return InitializeDllBlocklistOOPInternal(aFullImagePath, transferMgr,
nullptr);
}
#endif // defined(MOZ_ASAN) || defined(_M_ARM64)
} // namespace mozilla
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