Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / securestring.cs / 1 / securestring.cs
namespace System.Security {
using System.Security.Cryptography;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32;
using System.Runtime.CompilerServices;
using System.Security.Permissions;
using System.Runtime.ConstrainedExecution;
using System.Runtime.Versioning;
using Microsoft.Win32.SafeHandles;
public sealed class SecureString: IDisposable {
private SafeBSTRHandle m_buffer;
private int m_length;
private bool m_readOnly;
private bool m_enrypted;
static bool supportedOnCurrentPlatform = EncryptionSupported();
const int BlockSize = (int)Win32Native.CRYPTPROTECTMEMORY_BLOCK_SIZE /2; // a char is two bytes
const int MaxLength = 65536;
const uint ProtectionScope = Win32Native.CRYPTPROTECTMEMORY_SAME_PROCESS;
unsafe static bool EncryptionSupported() {
// check if the enrypt/decrypt function is supported on current OS
bool supported = true;
try {
Win32Native.SystemFunction041(
SafeBSTRHandle.Allocate(null , (int)Win32Native.CRYPTPROTECTMEMORY_BLOCK_SIZE),
Win32Native.CRYPTPROTECTMEMORY_BLOCK_SIZE,
Win32Native.CRYPTPROTECTMEMORY_SAME_PROCESS);
}
catch (EntryPointNotFoundException) {
supported = false;
}
return supported;
}
internal SecureString(SecureString str) {
AllocateBuffer(str.BufferLength);
SafeBSTRHandle.Copy(str.m_buffer, this.m_buffer);
m_length = str.m_length;
m_enrypted = str.m_enrypted;
}
public SecureString() {
CheckSupportedOnCurrentPlatform();
// allocate the minimum block size for calling protectMemory
AllocateBuffer(BlockSize);
m_length = 0;
}
[CLSCompliant(false)]
public unsafe SecureString(char* value, int length) {
if( value == null) {
throw new ArgumentNullException("value");
}
if( length < 0) {
throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
}
if( length > MaxLength) {
throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_Length"));
}
CheckSupportedOnCurrentPlatform();
AllocateBuffer(length);
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
m_buffer.AcquirePointer(ref bufferPtr);
Buffer.memcpyimpl((byte*)value, bufferPtr, length * 2);
}
finally
{
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
m_length = length;
ProtectMemory();
}
public int Length {
[MethodImplAttribute(MethodImplOptions.Synchronized)]
get {
EnsureNotDisposed();
return m_length;
}
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void AppendChar(char c) {
EnsureNotDisposed();
EnsureNotReadOnly();
EnsureCapacity(m_length + 1);
RuntimeHelpers.PrepareConstrainedRegions();
try {
UnProtectMemory();
m_buffer.Write((uint)m_length * sizeof(char), c);
m_length++;
}
finally {
ProtectMemory();
}
}
// clears the current contents. Only available if writable
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void Clear() {
EnsureNotDisposed();
EnsureNotReadOnly();
m_length = 0;
m_buffer.ClearBuffer();
m_enrypted = false;
}
// Do a deep-copy of the SecureString
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public SecureString Copy() {
EnsureNotDisposed();
return new SecureString(this);
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void Dispose() {
if(m_buffer != null && !m_buffer.IsInvalid) {
m_buffer.Close();
m_buffer = null;
}
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void InsertAt( int index, char c ) {
EnsureNotDisposed();
EnsureNotReadOnly();
if( index < 0 || index > m_length) {
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_IndexString"));
}
EnsureCapacity(m_length + 1);
unsafe {
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
UnProtectMemory();
m_buffer.AcquirePointer(ref bufferPtr);
char* pBuffer = (char*)bufferPtr;
for (int i = m_length; i > index; i--) {
pBuffer[i] = pBuffer[i - 1];
}
pBuffer[index] = c;
++m_length;
}
finally {
ProtectMemory();
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
}
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public bool IsReadOnly() {
EnsureNotDisposed();
return m_readOnly;
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void MakeReadOnly() {
EnsureNotDisposed();
m_readOnly = true;
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void RemoveAt( int index ) {
EnsureNotDisposed();
EnsureNotReadOnly();
if( index < 0 || index >= m_length) {
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_IndexString"));
}
unsafe
{
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
UnProtectMemory();
m_buffer.AcquirePointer(ref bufferPtr);
char* pBuffer = (char*)bufferPtr;
for (int i = index; i < m_length - 1; i++)
{
pBuffer[i] = pBuffer[i + 1];
}
pBuffer[--m_length] = (char)0;
}
finally
{
ProtectMemory();
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
}
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
public void SetAt( int index, char c ) {
EnsureNotDisposed();
EnsureNotReadOnly();
if( index < 0 || index >= m_length) {
throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_IndexString"));
}
RuntimeHelpers.PrepareConstrainedRegions();
try {
UnProtectMemory();
m_buffer.Write((uint)index * sizeof(char), c);
}
finally {
ProtectMemory();
}
}
private int BufferLength {
get {
BCLDebug.Assert(m_buffer != null, "Buffer is not initialized!");
return m_buffer.Length;
}
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
private void AllocateBuffer(int size) {
uint alignedSize = GetAlignedSize(size);
m_buffer = SafeBSTRHandle.Allocate(null, alignedSize);
if (m_buffer.IsInvalid) {
throw new OutOfMemoryException();
}
}
private void CheckSupportedOnCurrentPlatform() {
if( !supportedOnCurrentPlatform) {
throw new NotSupportedException(Environment.GetResourceString("Arg_PlatformSecureString"));
}
}
private void EnsureCapacity(int capacity) {
if( capacity <= m_buffer.Length) {
return;
}
if( capacity > MaxLength) {
throw new ArgumentOutOfRangeException("capacity", Environment.GetResourceString("ArgumentOutOfRange_Capacity"));
}
SafeBSTRHandle newBuffer = SafeBSTRHandle.Allocate(null, GetAlignedSize(capacity));
if (newBuffer.IsInvalid) {
throw new OutOfMemoryException();
}
SafeBSTRHandle.Copy(m_buffer, newBuffer);
m_buffer.Close();
m_buffer = newBuffer;
}
private void EnsureNotDisposed() {
if( m_buffer == null) {
throw new ObjectDisposedException(null);
}
}
private void EnsureNotReadOnly() {
if( m_readOnly) {
throw new InvalidOperationException(Environment.GetResourceString("InvalidOperation_ReadOnly"));
}
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
private static uint GetAlignedSize( int size) {
BCLDebug.Assert(size >= 0, "size must be non-negative");
uint alignedSize = ((uint)size / BlockSize) * BlockSize;
if( (size % BlockSize != 0) || size == 0) { // if size is 0, set allocated size to blocksize
alignedSize += BlockSize;
}
return alignedSize;
}
private unsafe int GetAnsiByteCount() {
const uint CP_ACP = 0;
const uint WC_NO_BEST_FIT_CHARS = 0x00000400;
uint flgs = WC_NO_BEST_FIT_CHARS;
uint DefaultCharUsed = (uint)'?';
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
m_buffer.AcquirePointer(ref bufferPtr);
return Win32Native.WideCharToMultiByte(
CP_ACP,
flgs,
(char*) bufferPtr,
m_length,
null,
0,
IntPtr.Zero,
new IntPtr((void*)&DefaultCharUsed));
}
finally {
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
}
private unsafe void GetAnsiBytes( byte * ansiStrPtr, int byteCount) {
const uint CP_ACP = 0;
const uint WC_NO_BEST_FIT_CHARS = 0x00000400;
uint flgs = WC_NO_BEST_FIT_CHARS;
uint DefaultCharUsed = (uint)'?';
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
m_buffer.AcquirePointer(ref bufferPtr);
Win32Native.WideCharToMultiByte(
CP_ACP,
flgs,
(char*) bufferPtr,
m_length,
ansiStrPtr,
byteCount - 1,
IntPtr.Zero,
new IntPtr((void*)&DefaultCharUsed));
*(ansiStrPtr + byteCount - 1) = (byte)0;
}
finally {
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
}
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
private void ProtectMemory() {
BCLDebug.Assert(!m_buffer.IsInvalid && m_buffer.Length != 0, "Invalid buffer!");
BCLDebug.Assert(m_buffer.Length % BlockSize == 0, "buffer length must be multiple of blocksize!");
if( m_length == 0 || m_enrypted) {
return;
}
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
// RtlEncryptMemory return an NTSTATUS
int status = Win32Native.SystemFunction040(m_buffer, (uint)m_buffer.Length * 2, ProtectionScope);
if (status < 0) { // non-negative numbers indicate success
throw new CryptographicException(Win32Native.LsaNtStatusToWinError(status));
}
m_enrypted = true;
}
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
[MethodImplAttribute(MethodImplOptions.Synchronized)]
internal unsafe IntPtr ToBSTR() {
EnsureNotDisposed();
int length = m_length;
IntPtr ptr = IntPtr.Zero;
IntPtr result = IntPtr.Zero;
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
ptr = Win32Native.SysAllocStringLen(null, length);
}
if (ptr == IntPtr.Zero) {
throw new OutOfMemoryException();
}
UnProtectMemory();
m_buffer.AcquirePointer(ref bufferPtr);
Buffer.memcpyimpl(bufferPtr, (byte*) ptr.ToPointer(), length *2);
result = ptr;
}
finally {
ProtectMemory();
if( result == IntPtr.Zero) {
// If we failed for any reason, free the new buffer
if (ptr != IntPtr.Zero) {
Win32Native.ZeroMemory(ptr, (uint)(length * 2));
Win32Native.SysFreeString(ptr);
}
}
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
return result;
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
internal unsafe IntPtr ToUniStr(bool allocateFromHeap) {
EnsureNotDisposed();
int length = m_length;
IntPtr ptr = IntPtr.Zero;
IntPtr result = IntPtr.Zero;
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
if( allocateFromHeap) {
ptr = Marshal.AllocHGlobal((length + 1) * 2);
}
else {
ptr = Marshal.AllocCoTaskMem((length + 1) * 2);
}
}
if (ptr == IntPtr.Zero) {
throw new OutOfMemoryException();
}
UnProtectMemory();
m_buffer.AcquirePointer(ref bufferPtr);
Buffer.memcpyimpl(bufferPtr, (byte*) ptr.ToPointer(), length *2);
char * endptr = (char *) ptr.ToPointer();
*(endptr + length) = '\0';
result = ptr;
}
finally {
ProtectMemory();
if( result == IntPtr.Zero) {
// If we failed for any reason, free the new buffer
if (ptr != IntPtr.Zero) {
Win32Native.ZeroMemory(ptr, (uint)(length * 2));
if( allocateFromHeap) {
Marshal.FreeHGlobal(ptr);
}
else {
Marshal.FreeCoTaskMem(ptr);
}
}
}
if (bufferPtr != null)
m_buffer.ReleasePointer();
}
return result;
}
[MethodImplAttribute(MethodImplOptions.Synchronized)]
internal unsafe IntPtr ToAnsiStr(bool allocateFromHeap) {
EnsureNotDisposed();
IntPtr ptr = IntPtr.Zero;
IntPtr result = IntPtr.Zero;
int byteCount = 0;
RuntimeHelpers.PrepareConstrainedRegions();
try {
// GetAnsiByteCount uses the string data, so the calculation must happen after we are decrypted.
UnProtectMemory();
// allocating an extra char for terminating zero
byteCount = GetAnsiByteCount() + 1;
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
if( allocateFromHeap) {
ptr = Marshal.AllocHGlobal(byteCount);
}
else {
ptr = Marshal.AllocCoTaskMem(byteCount);
}
}
if (ptr == IntPtr.Zero) {
throw new OutOfMemoryException();
}
GetAnsiBytes((byte *)ptr.ToPointer(), byteCount);
result = ptr;
}
finally {
ProtectMemory();
if( result == IntPtr.Zero) {
// If we failed for any reason, free the new buffer
if (ptr != IntPtr.Zero) {
Win32Native.ZeroMemory(ptr, (uint)byteCount);
if( allocateFromHeap) {
Marshal.FreeHGlobal(ptr);
}
else {
Marshal.FreeCoTaskMem(ptr);
}
}
}
}
return result;
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
private void UnProtectMemory() {
BCLDebug.Assert(!m_buffer.IsInvalid && m_buffer.Length != 0, "Invalid buffer!");
BCLDebug.Assert(m_buffer.Length % BlockSize == 0, "buffer length must be multiple of blocksize!");
if( m_length == 0) {
return;
}
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
if (m_enrypted) {
// RtlEncryptMemory return an NTSTATUS
int status = Win32Native.SystemFunction041(m_buffer, (uint)m_buffer.Length * 2, ProtectionScope);
if (status < 0)
{ // non-negative numbers indicate success
throw new CryptographicException(Win32Native.LsaNtStatusToWinError(status));
}
m_enrypted = false;
}
}
}
}
[SuppressUnmanagedCodeSecurityAttribute()]
internal sealed class SafeBSTRHandle : SafePointer {
internal SafeBSTRHandle () : base(true) {}
internal static SafeBSTRHandle Allocate(String src, uint len)
{
SafeBSTRHandle bstr = SysAllocStringLen(src, len);
bstr.Initialize(len * 2);
return bstr;
}
[ResourceExposure(ResourceScope.None)]
[DllImport(Win32Native.OLEAUT32, CharSet = CharSet.Unicode)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
private static extern SafeBSTRHandle SysAllocStringLen(String src, uint len); // BSTR
override protected bool ReleaseHandle() {
Win32Native.ZeroMemory(handle, (uint)Win32Native.SysStringLen(handle) * 2);
Win32Native.SysFreeString(handle);
return true;
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
internal unsafe void ClearBuffer() {
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
AcquirePointer(ref bufferPtr);
Win32Native.ZeroMemory((IntPtr)bufferPtr, (uint)Win32Native.SysStringLen((IntPtr)bufferPtr) * 2);
}
finally
{
if (bufferPtr != null)
ReleasePointer();
}
}
internal unsafe int Length {
get {
byte* bufferPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
AcquirePointer(ref bufferPtr);
return Win32Native.SysStringLen((IntPtr)bufferPtr);
}
finally
{
if (bufferPtr != null)
ReleasePointer();
}
}
}
internal unsafe static void Copy(SafeBSTRHandle source, SafeBSTRHandle target) {
byte* sourcePtr = null, targetPtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
source.AcquirePointer(ref sourcePtr);
target.AcquirePointer(ref targetPtr);
BCLDebug.Assert(Win32Native.SysStringLen((IntPtr)targetPtr) >= Win32Native.SysStringLen((IntPtr)sourcePtr), "Target buffer is not large enough!");
Buffer.memcpyimpl(sourcePtr, targetPtr, Win32Native.SysStringLen((IntPtr)sourcePtr) * 2);
}
finally
{
if (sourcePtr != null)
source.ReleasePointer();
if (targetPtr != null)
target.ReleasePointer();
}
}
}
}
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