public override void Render(ImageSegment segment, Program program, Formatter formatter) { // Get the entry that has the segment# for the string table. var dynStrtab = loader.GetDynEntries(shdr.FileOffset).Where(d => d.d_tag == DT_STRTAB).FirstOrDefault(); if (dynStrtab == null) { return; } this.strtabSection = loader.GetSectionInfoByAddr(dynStrtab.d_ptr); foreach (var entry in loader.GetDynEntries(shdr.FileOffset)) { DtFormat fmt; string entryName; if (!machineSpecific.TryGetValue(entry.d_tag, out Entry dser) && !entries.TryGetValue(entry.d_tag, out dser)) { entryName = string.Format("{0:X8} ", entry.d_tag); fmt = DtFormat.Hexadecimal; } else { entryName = dser.Name; fmt = dser.Format; } RenderEntry(entryName, fmt, entry, formatter); formatter.WriteLine(); } }
public void RelocateOld(Program program) { uint nextFakeLibAddr = ~1u; // See R_386_PC32 below; -1 sometimes used for main for (int i = 1; i < loader.Sections.Count; ++i) { var ps = loader.Sections[i]; if (ps.Type == SectionHeaderType.SHT_REL) { // A section such as .rel.dyn or .rel.plt (without an addend field). // Each entry has 2 words: r_offset and r_info. The r_offset is just the offset from the beginning // of the section (section given by the section header's sh_info) to the word to be modified. // r_info has the type in the bottom byte, and a symbol table index in the top 3 bytes. // A symbol table offset of 0 (STN_UNDEF) means use value 0. The symbol table involved comes from // the section header's sh_link field. var pReloc = loader.CreateReader(ps.FileOffset); ulong size = ps.Size; // NOTE: the r_offset is different for .o files (ET_REL in the e_type header field) than for exe's // and shared objects! uint destNatOrigin = 0; uint destHostOrigin = 0; if (loader.Header.e_type == ElfImageLoader.ET_REL) { var destSection = loader.Sections[i].RelocatedSection; destNatOrigin = destSection.Address.ToUInt32(); destHostOrigin = (uint)destSection.FileOffset; } var symSection = loader.Sections[i].LinkedSection; // associated symbol table var strSection = symSection.LinkedSection; // Section index for the string section assoc with this var pStrSection = strSection.FileOffset; var symOrigin = symSection.FileOffset; var relocR = loader.CreateReader(0); var relocW = loader.CreateWriter(0); for (uint u = 0; u < size; u += 2 * sizeof(uint)) { uint r_offset = pReloc.ReadUInt32(); uint info = pReloc.ReadUInt32(); byte relType = (byte)info; uint symTabIndex = info >> 8; uint pRelWord; // Pointer to the word to be relocated if (loader.Header.e_type == ElfImageLoader.ET_REL) { pRelWord = destHostOrigin + r_offset; } else { if (r_offset == 0) { continue; } var destSec = loader.GetSectionInfoByAddr(r_offset); pRelWord = ~0u; // destSec.uHostAddr - destSec.uNativeAddr + r_offset; destNatOrigin = 0; } uint A, S = 0, P; int nsec; var sym = Elf32_Sym.Load(loader.CreateReader(symOrigin + symTabIndex * Elf32_Sym.Size)); switch (relType) { case 0: // R_386_NONE: just ignore (common) break; case 1: // R_386_32: S + A // Read the symTabIndex'th symbol. S = sym.st_value; if (loader.Header.e_type == ElfImageLoader.ET_REL) { nsec = sym.st_shndx; if (nsec >= 0 && nsec < loader.Sections.Count) { S += loader.Sections[nsec].Address.ToUInt32(); } } A = relocR.ReadUInt32(pRelWord); relocW.WriteUInt32(pRelWord, S + A); break; case 2: // R_386_PC32: S + A - P if (ElfLoader32.ELF32_ST_TYPE(sym.st_info) == ElfLoader.STT_SECTION) { nsec = sym.st_shndx; if (nsec >= 0 && nsec < loader.Sections.Count) { S = loader.Sections[nsec].Address.ToUInt32(); } } else { S = sym.st_value; if (S == 0) { // This means that the symbol doesn't exist in this module, and is not accessed // through the PLT, i.e. it will be statically linked, e.g. strcmp. We have the // name of the symbol right here in the symbol table entry, but the only way // to communicate with the loader is through the target address of the call. // So we use some very improbable addresses (e.g. -1, -2, etc) and give them entries // in the symbol table uint nameOffset = sym.st_name; string pName = loader.ReadAsciiString(pStrSection + nameOffset); // this is too slow, I'm just going to assume it is 0 //S = GetAddressByName(pName); //if (S == (e_type == E_REL ? 0x8000000 : 0)) { S = nextFakeLibAddr--; // Allocate a new fake address loader.AddSymbol(S, pName); //} } else if (loader.Header.e_type == ElfImageLoader.ET_REL) { nsec = sym.st_shndx; if (nsec >= 0 && nsec < loader.Sections.Count) { S += loader.Sections[nsec].Address.ToUInt32(); } } } A = relocR.ReadUInt32(pRelWord); P = destNatOrigin + r_offset; relocW.WriteUInt32(pRelWord, S + A - P); break; case 6: // R_386_GLOB_DAT // This relocation type is used to set a global offset table entry to the address of the // specified symbol. The special relocation type allows one to determine the // correspondence between symbols and global offset table entries. S = sym.st_value; relocW.WriteUInt32(pRelWord, S); break; case 7: case 8: // R_386_RELATIVE break; // No need to do anything with these, if a shared object default: throw new NotSupportedException("Relocation type " + (int)relType + " not handled yet"); } } } } }
public override void Render(ImageSegment segment, Program program, Formatter formatter) { // Get the entry that has the segment# for the string table. var dynStrtab = loader.GetDynEntries(shdr.FileOffset).Where(d => d.d_tag == DT_STRTAB).FirstOrDefault(); if (dynStrtab == null) { return; } var strtabSection = loader.GetSectionInfoByAddr(dynStrtab.d_ptr); foreach (var entry in loader.GetDynEntries(shdr.FileOffset)) { switch (entry.d_tag) { default: formatter.Write("{0,-12} {1:X8}", entry.d_tag, entry.d_val); break; case DT_DEBUG: formatter.Write("{0,-12} {1:X8}", "DT_DEBUG", entry.d_val); break; case DT_FINI: formatter.Write("{0,-12} ", "DT_FINI"); formatter.WriteHyperlink(string.Format("{0:X8}", entry.d_ptr), Address.Ptr32(entry.d_ptr)); break; case DT_HASH: formatter.Write("{0,-12} ", "DT_HASH"); formatter.WriteHyperlink(string.Format("{0:X8}", entry.d_ptr), Address.Ptr32(entry.d_ptr)); break; case DT_INIT: formatter.Write("{0,-12} ", "DT_INIT"); formatter.WriteHyperlink(string.Format("{0:X8}", entry.d_ptr), Address.Ptr32(entry.d_ptr)); break; case DT_JMPREL: formatter.Write("{0,-12} ", "DT_JMPREL"); formatter.WriteHyperlink(string.Format("{0:X8}", entry.d_ptr), Address.Ptr32(entry.d_ptr)); break; case DT_NEEDED: formatter.Write("{0,-12} {1}", "DT_NEEDED", loader.ReadAsciiString(strtabSection.FileOffset + entry.d_ptr)); break; case DT_STRSZ: formatter.Write("{0,-12} {1:X}", "DT_STRSZ", entry.d_val); break; case DT_STRTAB: formatter.Write("{0,-12} ", "DT_STRTAB"); formatter.WriteHyperlink(string.Format("{0:X8}", entry.d_ptr), Address.Ptr32(entry.d_ptr)); break; case DT_SYMENT: formatter.Write("{0,-12} {1}", "DT_SYMENTTRTAB", entry.d_val); break; case DT_SYMTAB: formatter.Write("{0,-12} ", "DT_SYMTAB"); formatter.WriteHyperlink(string.Format("{0:X8}", entry.d_ptr), Address.Ptr32(entry.d_ptr)); break; } formatter.WriteLine(); } }