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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sandbox/win/src/service_resolver.h"
#include "base/memory/scoped_ptr.h"
#include "sandbox/win/src/sandbox_nt_util.h"
#include "sandbox/win/src/win_utils.h"
namespace {
#pragma pack(push, 1)
const ULONG kMmovR10EcxMovEax = 0xB8D18B4C;
const USHORT kSyscall = 0x050F;
const BYTE kRetNp = 0xC3;
const ULONG64 kMov1 = 0x54894808244C8948;
const ULONG64 kMov2 = 0x4C182444894C1024;
const ULONG kMov3 = 0x20244C89;
// Service code for 64 bit systems.
struct ServiceEntry {
// This struct contains roughly the following code:
// 00 mov r10,rcx
// 03 mov eax,52h
// 08 syscall
// 0a ret
// 0b xchg ax,ax
// 0e xchg ax,ax
ULONG mov_r10_rcx_mov_eax; // = 4C 8B D1 B8
ULONG service_id;
USHORT syscall; // = 0F 05
BYTE ret; // = C3
BYTE pad; // = 66
USHORT xchg_ax_ax1; // = 66 90
USHORT xchg_ax_ax2; // = 66 90
};
// Service code for 64 bit Windows 8.
struct ServiceEntryW8 {
// This struct contains the following code:
// 00 48894c2408 mov [rsp+8], rcx
// 05 4889542410 mov [rsp+10], rdx
// 0a 4c89442418 mov [rsp+18], r8
// 0f 4c894c2420 mov [rsp+20], r9
// 14 4c8bd1 mov r10,rcx
// 17 b825000000 mov eax,25h
// 1c 0f05 syscall
// 1e c3 ret
// 1f 90 nop
ULONG64 mov_1; // = 48 89 4C 24 08 48 89 54
ULONG64 mov_2; // = 24 10 4C 89 44 24 18 4C
ULONG mov_3; // = 89 4C 24 20
ULONG mov_r10_rcx_mov_eax; // = 4C 8B D1 B8
ULONG service_id;
USHORT syscall; // = 0F 05
BYTE ret; // = C3
BYTE nop; // = 90
};
// We don't have an internal thunk for x64.
struct ServiceFullThunk {
union {
ServiceEntry original;
ServiceEntryW8 original_w8;
};
};
#pragma pack(pop)
bool IsService(const void* source) {
const ServiceEntry* service =
reinterpret_cast<const ServiceEntry*>(source);
return (kMmovR10EcxMovEax == service->mov_r10_rcx_mov_eax &&
kSyscall == service->syscall && kRetNp == service->ret);
}
}; // namespace
namespace sandbox {
NTSTATUS ServiceResolverThunk::Setup(const void* target_module,
const void* interceptor_module,
const char* target_name,
const char* interceptor_name,
const void* interceptor_entry_point,
void* thunk_storage,
size_t storage_bytes,
size_t* storage_used) {
NTSTATUS ret = Init(target_module, interceptor_module, target_name,
interceptor_name, interceptor_entry_point,
thunk_storage, storage_bytes);
if (!NT_SUCCESS(ret))
return ret;
size_t thunk_bytes = GetThunkSize();
scoped_ptr<char[]> thunk_buffer(new char[thunk_bytes]);
ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(
thunk_buffer.get());
if (!IsFunctionAService(&thunk->original))
return STATUS_UNSUCCESSFUL;
ret = PerformPatch(thunk, thunk_storage);
if (NULL != storage_used)
*storage_used = thunk_bytes;
return ret;
}
size_t ServiceResolverThunk::GetThunkSize() const {
return sizeof(ServiceFullThunk);
}
NTSTATUS ServiceResolverThunk::CopyThunk(const void* target_module,
const char* target_name,
BYTE* thunk_storage,
size_t storage_bytes,
size_t* storage_used) {
NTSTATUS ret = ResolveTarget(target_module, target_name, &target_);
if (!NT_SUCCESS(ret))
return ret;
size_t thunk_bytes = GetThunkSize();
if (storage_bytes < thunk_bytes)
return STATUS_UNSUCCESSFUL;
ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(thunk_storage);
if (!IsFunctionAService(&thunk->original))
return STATUS_UNSUCCESSFUL;
if (NULL != storage_used)
*storage_used = thunk_bytes;
return ret;
}
bool ServiceResolverThunk::IsFunctionAService(void* local_thunk) const {
ServiceFullThunk function_code;
SIZE_T read;
if (!::ReadProcessMemory(process_, target_, &function_code,
sizeof(function_code), &read))
return false;
if (sizeof(function_code) != read)
return false;
if (!IsService(&function_code)) {
// See if it's the Win8 signature.
ServiceEntryW8* w8_service = &function_code.original_w8;
if (!IsService(&w8_service->mov_r10_rcx_mov_eax) ||
w8_service->mov_1 != kMov1 || w8_service->mov_1 != kMov1 ||
w8_service->mov_1 != kMov1) {
return false;
}
}
// Save the verified code.
memcpy(local_thunk, &function_code, sizeof(function_code));
return true;
}
NTSTATUS ServiceResolverThunk::PerformPatch(void* local_thunk,
void* remote_thunk) {
// Patch the original code.
ServiceEntry local_service;
DCHECK_NT(GetInternalThunkSize() >= sizeof(local_service));
if (!SetInternalThunk(&local_service, sizeof(local_service), NULL,
interceptor_))
return STATUS_UNSUCCESSFUL;
// Copy the local thunk buffer to the child.
SIZE_T actual;
if (!::WriteProcessMemory(process_, remote_thunk, local_thunk,
sizeof(ServiceFullThunk), &actual))
return STATUS_UNSUCCESSFUL;
if (sizeof(ServiceFullThunk) != actual)
return STATUS_UNSUCCESSFUL;
// And now change the function to intercept, on the child.
if (NULL != ntdll_base_) {
// Running a unit test.
if (!::WriteProcessMemory(process_, target_, &local_service,
sizeof(local_service), &actual))
return STATUS_UNSUCCESSFUL;
} else {
if (!WriteProtectedChildMemory(process_, target_, &local_service,
sizeof(local_service)))
return STATUS_UNSUCCESSFUL;
}
return STATUS_SUCCESS;
}
bool Wow64ResolverThunk::IsFunctionAService(void* local_thunk) const {
NOTREACHED_NT();
return false;
}
} // namespace sandbox
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