/// <summary>
/// Always uses big endian!!!
/// Converts a blob back into an array of bytes (does not work if there are any file-absolute offsets, as it serializes starting at 0 of a fake stream)
/// </summary>
public byte[] GetBlobBytes()
{
MemoryStream MemoryBuffer = new MemoryStream();
BinaryWriter Writer = new BinaryWriter(MemoryBuffer);
WritingContext SW = new WritingContext(Writer);
SW.bStreamLittleEndian = false;
Write(SW);
SW.CompleteWritingAndClose();
return MemoryBuffer.ToArray();
}
/// <summary>
/// Does the actual work of signing the application
/// Modifies the following files:
/// Info.plist
/// [Executable] (file name derived from CFBundleExecutable in the Info.plist, e.g., UDKGame)
/// _CodeSignature/CodeResources
/// [ResourceRules] (file name derived from CFBundleResourceSpecification, e.g., CustomResourceRules.plist)
/// </summary>
public void PerformSigning()
{
DateTime SigningTime = DateTime.Now;
// Get the name of the executable file
string CFBundleExecutable;
if (!Info.GetString("CFBundleExecutable", out CFBundleExecutable))
{
throw new InvalidDataException("Info.plist must contain the key CFBundleExecutable");
}
// Get the name of the bundle
string CFBundleIdentifier;
if (!Info.GetString("CFBundleIdentifier", out CFBundleIdentifier))
{
throw new InvalidDataException("Info.plist must contain the key CFBundleIdentifier");
}
// Verify there is a resource rules file and make a dummy one if needed.
// If it's missing, CreateCodeResourceDirectory can't proceed (the Info.plist is already written to disk at that point)
if (!Info.HasKey("CFBundleResourceSpecification"))
{
// Couldn't find the key, create a dummy one
string CFBundleResourceSpecification = "CustomResourceRules.plist";
Info.SetString("CFBundleResourceSpecification", CFBundleResourceSpecification);
Program.Warning("Info.plist was missing the key CFBundleResourceSpecification, creating a new resource rules file '{0}'.", CFBundleResourceSpecification);
}
// Save the Info.plist out
byte[] RawInfoPList = Encoding.UTF8.GetBytes(Info.SaveToString());
Info.SetReadOnly(true);
FileSystem.WriteAllBytes("Info.plist", RawInfoPList);
Program.Log(" ... Writing updated Info.plist");
// Create the code resources file and load it
byte[] ResourceDirBytes = CreateCodeResourcesDirectory(CFBundleExecutable);
// Open the executable
Program.Log("Opening source executable...");
byte[] SourceExeData = FileSystem.ReadAllBytes(CFBundleExecutable);
FatBinaryFile FatBinary = new FatBinaryFile();
FatBinary.LoadFromBytes(SourceExeData);
//@TODO: Verify it's an executable (not an object file, etc...)
ulong CurrentStreamOffset = 0;
byte[] FinalExeData = new byte[SourceExeData.Length + 1024 * 1024];
int ArchIndex = 0;
foreach (MachObjectFile Exe in FatBinary.MachObjectFiles)
{
Program.Log("... Processing one mach object (binary is {0})", FatBinary.bIsFatBinary ? "fat" : "thin");
// Pad the memory stream with extra room to handle any possible growth in the code signing data
int OverSize = 1024 * 1024;
int ExeSize = (FatBinary.bIsFatBinary ? (int)FatBinary.Archs[ArchIndex].Size : SourceExeData.Length);
MemoryStream OutputExeStream = new MemoryStream(ExeSize + OverSize);
// Copy the data up to the executable into the final stream
if (FatBinary.bIsFatBinary)
{
if (ArchIndex == 0)
{
OutputExeStream.Seek(0, SeekOrigin.Begin);
OutputExeStream.Write(SourceExeData, (int)CurrentStreamOffset, (int)FatBinary.Archs[ArchIndex].Offset - (int)CurrentStreamOffset);
OutputExeStream.Seek(0, SeekOrigin.Begin);
byte[] HeaderData = OutputExeStream.ToArray();
HeaderData.CopyTo(FinalExeData, (long)CurrentStreamOffset);
CurrentStreamOffset += (ulong)HeaderData.Length;
}
else
{
byte[] ZeroData = new byte[(int)FatBinary.Archs[ArchIndex].Offset - (int)CurrentStreamOffset];
ZeroData.CopyTo(FinalExeData, (long)CurrentStreamOffset);
CurrentStreamOffset += (ulong)ZeroData.Length;
}
}
// Copy the executable into the stream
int ExeOffset = (FatBinary.bIsFatBinary ? (int)FatBinary.Archs[ArchIndex].Offset : 0);
OutputExeStream.Seek(0, SeekOrigin.Begin);
OutputExeStream.Write(SourceExeData, ExeOffset, ExeSize);
OutputExeStream.Seek(0, SeekOrigin.Begin);
long Length = OutputExeStream.Length;
// Find out if there was an existing code sign blob and find the linkedit segment command
MachLoadCommandCodeSignature CodeSigningBlobLC = null;
MachLoadCommandSegment LinkEditSegmentLC = null;
foreach (MachLoadCommand Command in Exe.Commands)
{
if (CodeSigningBlobLC == null)
{
CodeSigningBlobLC = Command as MachLoadCommandCodeSignature;
}
if (LinkEditSegmentLC == null)
{
LinkEditSegmentLC = Command as MachLoadCommandSegment;
if (LinkEditSegmentLC.SegmentName != "__LINKEDIT")
{
LinkEditSegmentLC = null;
}
}
}
if (LinkEditSegmentLC == null)
{
throw new InvalidDataException("Did not find a Mach segment load command for the __LINKEDIT segment");
}
// If the existing code signing blob command is missing, make sure there is enough space to add it
// Insert the code signing blob if it isn't present
//@TODO: Insert the code signing blob if it isn't present
if (CodeSigningBlobLC == null)
{
throw new InvalidDataException("Did not find a Code Signing LC. Injecting one into a fresh executable is not currently supported.");
}
// Verify that the code signing blob is at the end of the linkedit segment (and thus can be expanded if needed)
if ((CodeSigningBlobLC.BlobFileOffset + CodeSigningBlobLC.BlobFileSize) != (LinkEditSegmentLC.FileOffset + LinkEditSegmentLC.FileSize))
{
throw new InvalidDataException("Code Signing LC was present but not at the end of the __LINKEDIT segment, unable to replace it");
}
int SignedFileLength = (int)CodeSigningBlobLC.BlobFileOffset;
// Create the code directory blob
CodeDirectoryBlob FinalCodeDirectoryBlob = CodeDirectoryBlob.Create(CFBundleIdentifier, SignedFileLength);
// Create the entitlements blob
string EntitlementsText = BuildEntitlementString(CFBundleIdentifier);
EntitlementsBlob FinalEntitlementsBlob = EntitlementsBlob.Create(EntitlementsText);
// Create or preserve the requirements blob
RequirementsBlob FinalRequirementsBlob = null;
if ((CodeSigningBlobLC != null) && Config.bMaintainExistingRequirementsWhenCodeSigning)
{
RequirementsBlob OldRequirements = CodeSigningBlobLC.Payload.GetBlobByMagic(AbstractBlob.CSMAGIC_REQUIREMENTS_TABLE) as RequirementsBlob;
FinalRequirementsBlob = OldRequirements;
}
if (FinalRequirementsBlob == null)
{
FinalRequirementsBlob = RequirementsBlob.CreateEmpty();
}
// Create the code signature blob (which actually signs the code directory)
CodeDirectorySignatureBlob CodeSignatureBlob = CodeDirectorySignatureBlob.Create();
// Create the code signature superblob (which contains all of the other signature-related blobs)
CodeSigningTableBlob CodeSignPayload = CodeSigningTableBlob.Create();
CodeSignPayload.Add(0x00000, FinalCodeDirectoryBlob);
CodeSignPayload.Add(0x00002, FinalRequirementsBlob);
CodeSignPayload.Add(0x00005, FinalEntitlementsBlob);
CodeSignPayload.Add(0x10000, CodeSignatureBlob);
// The ordering of the following steps (and doing the signature twice below) must be preserved.
// The reason is there are some chicken-and-egg issues here:
// The code directory stores a hash of the header, but
// The header stores the size of the __LINKEDIT section, which is where the signature blobs go, but
// The CMS signature blob signs the code directory
//
// So, we need to know the size of a signature blob in order to write a header that is itself hashed
// and signed by the signature blob
// Do an initial signature just to get the size
Program.Log("... Initial signature step ({0:0.00} s elapsed so far)", (DateTime.Now - SigningTime).TotalSeconds);
CodeSignatureBlob.SignCodeDirectory(SigningCert, SigningTime, FinalCodeDirectoryBlob);
// Compute the size of everything, and push it into the EXE header
byte[] DummyPayload = CodeSignPayload.GetBlobBytes();
// Adjust the header and load command to have the correct size for the code sign blob
WritingContext OutputExeContext = new WritingContext(new BinaryWriter(OutputExeStream));
long BlobLength = DummyPayload.Length;
long NonCodeSigSize = (long)LinkEditSegmentLC.FileSize - CodeSigningBlobLC.BlobFileSize;
long BlobStartPosition = NonCodeSigSize + (long)LinkEditSegmentLC.FileOffset;
LinkEditSegmentLC.PatchFileLength(OutputExeContext, (uint)(NonCodeSigSize + BlobLength));
CodeSigningBlobLC.PatchPositionAndSize(OutputExeContext, (uint)BlobStartPosition, (uint)BlobLength);
// Now that the executable loader command has been inserted and the appropriate section modified, compute all the hashes
Program.Log("... Computing hashes ({0:0.00} s elapsed so far)", (DateTime.Now - SigningTime).TotalSeconds);
OutputExeContext.Flush();
// Fill out the special hashes
FinalCodeDirectoryBlob.GenerateSpecialSlotHash(CodeDirectoryBlob.cdInfoSlot, RawInfoPList);
FinalCodeDirectoryBlob.GenerateSpecialSlotHash(CodeDirectoryBlob.cdRequirementsSlot, FinalRequirementsBlob.GetBlobBytes());
FinalCodeDirectoryBlob.GenerateSpecialSlotHash(CodeDirectoryBlob.cdResourceDirSlot, ResourceDirBytes);
FinalCodeDirectoryBlob.GenerateSpecialSlotHash(CodeDirectoryBlob.cdApplicationSlot);
FinalCodeDirectoryBlob.GenerateSpecialSlotHash(CodeDirectoryBlob.cdEntitlementSlot, FinalEntitlementsBlob.GetBlobBytes());
// Fill out the regular hashes
FinalCodeDirectoryBlob.ComputeImageHashes(OutputExeStream.ToArray());
// And compute the final signature
Program.Log("... Final signature step ({0:0.00} s elapsed so far)", (DateTime.Now - SigningTime).TotalSeconds);
CodeSignatureBlob.SignCodeDirectory(SigningCert, SigningTime, FinalCodeDirectoryBlob);
// Generate the signing blob and place it in the output (verifying it didn't change in size)
byte[] FinalPayload = CodeSignPayload.GetBlobBytes();
if (DummyPayload.Length != FinalPayload.Length)
{
throw new InvalidDataException("CMS signature blob changed size between practice run and final run, unable to create useful code signing data");
}
OutputExeContext.PushPositionAndJump(BlobStartPosition);
OutputExeContext.Write(FinalPayload);
OutputExeContext.PopPosition();
// Truncate the data so the __LINKEDIT section extends right to the end
Program.Log("... Committing all edits ({0:0.00} s elapsed so far)", (DateTime.Now - SigningTime).TotalSeconds);
OutputExeContext.CompleteWritingAndClose();
Program.Log("... Truncating/copying final binary", DateTime.Now - SigningTime);
ulong DesiredExecutableLength = LinkEditSegmentLC.FileSize + LinkEditSegmentLC.FileOffset;
if ((ulong)Length < DesiredExecutableLength)
{
throw new InvalidDataException("Data written is smaller than expected, unable to finish signing process");
}
byte[] Data = OutputExeStream.ToArray();
Data.CopyTo(FinalExeData, (long)CurrentStreamOffset);
CurrentStreamOffset += DesiredExecutableLength;
// update the header if it is a fat binary
if (FatBinary.bIsFatBinary)
{
FatBinary.Archs[ArchIndex].Size = (uint)DesiredExecutableLength;
}
// increment the architecture index
ArchIndex++;
}
// re-write the header
FatBinary.WriteHeader(ref FinalExeData, 0);
// resize to the finale size
Array.Resize(ref FinalExeData, (int)CurrentStreamOffset); //@todo: Extend the file system interface so we don't have to copy 20 MB just to truncate a few hundred bytes
// Save the patched and signed executable
Program.Log("Saving signed executable... ({0:0.00} s elapsed so far)", (DateTime.Now - SigningTime).TotalSeconds);
FileSystem.WriteAllBytes(CFBundleExecutable, FinalExeData);
Program.Log("Finished code signing, which took {0:0.00} s", (DateTime.Now - SigningTime).TotalSeconds);
}
public void Write(WritingContext Context)
{
// Write the header
Context.Write(Magic);
Context.Write(CpuType);
Context.Write(CpuSubType);
Context.Write(FileType);
Context.Write((UInt32)Commands.Count);
LengthFieldU32or64 SizeOfCommands = Context.WriteDeferredLength(-2 * sizeof(UInt32), Bits.Num._32); // Size of commands, after this field and the flags field
Context.Write(Flags);
if (Magic == MH_MAGIC_64)
{
Context.Write(Reserved64);
}
// Write each command (which may enqueue deferred work)
foreach (MachLoadCommand Command in Commands)
{
Command.Write(Context);
}
Context.CommitDeferredField(SizeOfCommands);
//@TODO: Figure out where this offsetting comes from
long MainStartPosition = MachHeaderPad;
Context.WriteZeros(MainStartPosition - Context.Position);
// Drain deferred work until the file is completely done
Context.CompleteWritingAndClose();
}
