Files
libexeinfo/libexeinfo/ELF/ELF.cs
2018-03-13 18:10:09 +00:00

340 lines
14 KiB
C#

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
namespace libexeinfo
{
public partial class ELF : IExecutable
{
List<Architecture> architectures;
Elf64_Ehdr Header;
string interpreter;
string[] sectionNames;
Elf64_Shdr[] sections;
Dictionary<string, ElfNote> notes;
/// <summary>
/// Initializes a new instance of the <see cref="T:libexeinfo.ELF" /> class.
/// </summary>
/// <param name="path">Executable path.</param>
public ELF(string path)
{
BaseStream = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
string pathDir = Path.GetDirectoryName(path);
string filename = Path.GetFileNameWithoutExtension(path);
string testPath = Path.Combine(pathDir, filename);
string resourceFilePath = null;
Initialize();
}
/// <summary>
/// Initializes a new instance of the <see cref="T:libexeinfo.ELF" /> class.
/// </summary>
/// <param name="stream">Stream containing the executable.</param>
public ELF(Stream stream)
{
BaseStream = stream;
Initialize();
}
/// <summary>
/// Initializes a new instance of the <see cref="T:libexeinfo.ELF" /> class.
/// </summary>
/// <param name="data">Byte array containing the executable.</param>
public ELF(byte[] data)
{
BaseStream = new MemoryStream(data);
Initialize();
}
public bool Recognized { get; private set; }
public string Type { get; private set; }
public IEnumerable<Architecture> Architectures => architectures;
public OperatingSystem RequiredOperatingSystem { get; private set; }
public IEnumerable<string> Strings { get; private set; }
public IEnumerable<Segment> Segments { get; }
/// <summary>
/// The <see cref="FileStream" /> that contains the executable represented by this instance
/// </summary>
public Stream BaseStream { get; }
public bool IsBigEndian { get; private set; }
void Initialize()
{
Recognized = false;
if(BaseStream == null) return;
byte[] buffer = new byte[Marshal.SizeOf(typeof(Elf64_Ehdr))];
BaseStream.Position = 0;
BaseStream.Read(buffer, 0, buffer.Length);
Header = BigEndianMarshal.ByteArrayToStructureLittleEndian<Elf64_Ehdr>(buffer);
Recognized = Header.ei_mag.SequenceEqual(ELFMAG);
if(!Recognized) return;
Type = "Executable and Linkable Format (ELF)";
IsBigEndian = Header.ei_data == eiData.ELFDATA2MSB;
architectures = new List<Architecture>();
switch(Header.ei_class)
{
case eiClass.ELFCLASS32:
Header = UpBits(buffer, Header.ei_data == eiData.ELFDATA2MSB);
break;
case eiClass.ELFCLASS64:
if(Header.ei_data == eiData.ELFDATA2MSB)
{
Header = BigEndianMarshal.ByteArrayToStructureBigEndian<Elf64_Ehdr>(buffer);
Header.e_type = (eType)Swapping.Swap((ushort)Header.e_type);
Header.e_machine = (eMachine)Swapping.Swap((ushort)Header.e_machine);
Header.e_version = (eVersion)Swapping.Swap((uint)Header.e_version);
}
else Header = BigEndianMarshal.ByteArrayToStructureLittleEndian<Elf64_Ehdr>(buffer);
break;
default: return;
}
if(Header.ei_data != eiData.ELFDATA2LSB && Header.ei_data != eiData.ELFDATA2MSB ||
Header.ei_version != eiVersion.EV_CURRENT) return;
List<string> strings = new List<string>();
BaseStream.Position = (long)Header.e_shoff;
buffer = new byte[Header.e_shentsize];
sections = new Elf64_Shdr[Header.e_shnum];
for(int i = 0; i < sections.Length; i++)
{
BaseStream.Read(buffer, 0, buffer.Length);
switch(Header.ei_class)
{
case eiClass.ELFCLASS32:
sections[i] = UpBitsSection(buffer, Header.ei_data == eiData.ELFDATA2MSB);
break;
case eiClass.ELFCLASS64:
if(Header.ei_data == eiData.ELFDATA2MSB)
{
sections[i] = BigEndianMarshal.ByteArrayToStructureBigEndian<Elf64_Shdr>(buffer);
sections[i].sh_flags = (shFlags64)Swapping.Swap((ulong)sections[i].sh_flags);
sections[i].sh_type = (shType)Swapping.Swap((uint)sections[i].sh_type);
}
else sections[i] = BigEndianMarshal.ByteArrayToStructureLittleEndian<Elf64_Shdr>(buffer);
break;
default: return;
}
}
BaseStream.Position = (long)sections[Header.e_shstrndx].sh_offset;
buffer = new byte[sections[Header.e_shstrndx].sh_size];
BaseStream.Read(buffer, 0, buffer.Length);
sectionNames = new string[sections.Length];
Segment[] segments = new Segment[sections.Length];
int len = 0;
int pos;
for(int i = 0; i < sections.Length; i++)
{
pos = (int)sections[i].sh_name;
len = 0;
for(int p = pos; p < buffer.Length; p++)
{
if(buffer[p] == 0x00) break;
len++;
}
sectionNames[i] = Encoding.ASCII.GetString(buffer, pos, len);
strings.Add(sectionNames[i]);
segments[i] = new Segment
{
Flags = $"{sections[i].sh_flags}",
Name = sectionNames[i],
Offset = (long)sections[i].sh_offset,
Size = (long)sections[i].sh_size
};
}
int strStart = 0;
len = 0;
for(int p = 0; p < buffer.Length; p++)
{
if(buffer[p] == 0x00)
{
if(len == 0) continue;
strings.Add(Encoding.ASCII.GetString(buffer, strStart, len));
strStart = p + 1;
len = 0;
continue;
}
len++;
}
notes = new Dictionary<string, ElfNote>();
// Sections that contain an array of null-terminated strings by definition
for(int i = 0; i < sections.Length; i++)
{
BaseStream.Position = (long)sections[i].sh_offset;
buffer = new byte[sections[i].sh_size];
BaseStream.Read(buffer, 0, buffer.Length);
if(sectionNames[i] == ".interp" || sectionNames[i] == ".dynstr" || sectionNames[i] == ".comment")
{
strStart = 0;
len = 0;
for(int p = 0; p < buffer.Length; p++)
{
if(buffer[p] == 0x00)
{
if(len == 0) continue;
strings.Add(Encoding.ASCII.GetString(buffer, strStart, len));
if(sectionNames[i] == ".interp")
interpreter = Encoding.ASCII.GetString(buffer, strStart, len);
strStart = p + 1;
len = 0;
continue;
}
len++;
}
}
else if(sectionNames[i].StartsWith(".note"))
{
uint namesz = BitConverter.ToUInt32(buffer, 0);
uint descsz = BitConverter.ToUInt32(buffer, 4);
uint notetype = BitConverter.ToUInt32(buffer, 8);
pos = 12;
if(IsBigEndian)
{
namesz= Swapping.Swap(namesz);
descsz = Swapping.Swap(descsz);
notetype = Swapping.Swap(notetype);
}
ElfNote note = new ElfNote
{
name = Encoding.ASCII.GetString(buffer, pos, (int)(namesz - 1)),
type = notetype,
contents = new byte[descsz]
};
pos += (int)namesz;
switch(Header.ei_class) {
case eiClass.ELFCLASS32: pos += pos % 4;
break;
case eiClass.ELFCLASS64: pos += pos % 8;
break;
}
Array.Copy(buffer, pos, note.contents, 0, descsz);
notes.Add(sectionNames[i], note);
}
}
if(strings.Count > 0)
{
strings.Remove(null);
strings.Remove("");
strings.Sort();
Strings = strings.Distinct();
}
}
static Elf64_Ehdr UpBits(byte[] buffer, bool bigEndian)
{
Elf32_Ehdr ehdr32 = bigEndian
? BigEndianMarshal.ByteArrayToStructureBigEndian<Elf32_Ehdr>(buffer)
: BigEndianMarshal.ByteArrayToStructureLittleEndian<Elf32_Ehdr>(buffer);
return new Elf64_Ehdr
{
ei_mag = ehdr32.ei_mag,
ei_class = ehdr32.ei_class,
ei_data = ehdr32.ei_data,
ei_version = ehdr32.ei_version,
ei_osabi = ehdr32.ei_osabi,
ei_abiversion = ehdr32.ei_abiversion,
ei_pad = ehdr32.ei_pad,
e_type = bigEndian ? (eType)Swapping.Swap((ushort)ehdr32.e_type) : ehdr32.e_type,
e_machine = bigEndian ? (eMachine)Swapping.Swap((ushort)ehdr32.e_machine) : ehdr32.e_machine,
e_version = bigEndian ? (eVersion)Swapping.Swap((uint)ehdr32.e_version) : ehdr32.e_version,
e_entry = ehdr32.e_entry,
e_phoff = ehdr32.e_phoff,
e_shoff = ehdr32.e_shoff,
e_flags = ehdr32.e_flags,
e_ehsize = ehdr32.e_ehsize,
e_phentsize = ehdr32.e_phentsize,
e_phnum = ehdr32.e_phnum,
e_shentsize = ehdr32.e_shentsize,
e_shnum = ehdr32.e_shnum,
e_shstrndx = ehdr32.e_shstrndx
};
}
static Elf64_Shdr UpBitsSection(byte[] buffer, bool bigEndian)
{
Elf32_Shdr shdr32 = bigEndian
? BigEndianMarshal.ByteArrayToStructureBigEndian<Elf32_Shdr>(buffer)
: BigEndianMarshal.ByteArrayToStructureLittleEndian<Elf32_Shdr>(buffer);
return new Elf64_Shdr
{
sh_name = shdr32.sh_name,
sh_type = bigEndian ? (shType)Swapping.Swap((uint)shdr32.sh_type) : shdr32.sh_type,
sh_flags = (shFlags64)(bigEndian ? Swapping.Swap((uint)shdr32.sh_flags) : (uint)shdr32.sh_flags),
sh_addr = shdr32.sh_addr,
sh_offset = shdr32.sh_offset,
sh_size = shdr32.sh_size,
sh_link = shdr32.sh_link,
sh_info = shdr32.sh_info,
sh_addralign = shdr32.sh_addralign,
sh_entsize = shdr32.sh_entsize
};
}
/// <summary>
/// Identifies if the specified executable is an Executable and Linkable Format
/// </summary>
/// <returns><c>true</c> if the specified executable is an Executable and Linkable Format, <c>false</c> otherwise.</returns>
/// <param name="path">Executable path.</param>
public static bool Identify(string path)
{
FileStream exeFs = File.Open(path, FileMode.Open, FileAccess.Read);
return Identify(exeFs);
}
/// <summary>
/// Identifies if the specified executable is an Executable and Linkable Format
/// </summary>
/// <returns><c>true</c> if the specified executable is an Executable and Linkable Format, <c>false</c> otherwise.</returns>
/// <param name="stream">Stream containing the executable.</param>
public static bool Identify(FileStream stream)
{
byte[] buffer = new byte[Marshal.SizeOf(typeof(Elf32_Ehdr))];
stream.Position = 0;
stream.Read(buffer, 0, buffer.Length);
IntPtr hdrPtr = Marshal.AllocHGlobal(buffer.Length);
Marshal.Copy(buffer, 0, hdrPtr, buffer.Length);
Elf32_Ehdr elfHdr = (Elf32_Ehdr)Marshal.PtrToStructure(hdrPtr, typeof(Elf32_Ehdr));
Marshal.FreeHGlobal(hdrPtr);
return elfHdr.ei_mag.SequenceEqual(ELFMAG);
}
}
}