Usermode/Libraries/ld-acess.so_src/elf.c

   1 /*
   2  * Acess2 Dynamic Linker
   3  * - By John Hodge (thePowersGang)
   4  *
   5  * elf.c
   6  * - ELF32/ELF64 relocation
   7  */
   8 #ifndef DEBUG   // This code is #include'd from the kernel, so DEBUG may already be defined
   9 # define DEBUG  0
  10 #endif
  11
  12 #ifndef PAGE_SIZE
  13 # define PAGE_SIZE      4096
  14 #endif
  15
  16 #include "common.h"
  17 #include <stdint.h>
  18 #include <assert.h>
  19 #include "elf32.h"
  20 #include "elf64.h"
  21
  22 #if DEBUG
  23 # define        DEBUGS(v...)    SysDebug("ld-acess - " v)
  24 #else
  25 # define        DEBUGS(...)
  26 #endif
  27
  28 #ifndef DISABLE_ELF64
  29 # define SUPPORT_ELF64
  30 #endif
  31
  32 // === CONSTANTS ===
  33 #if DEBUG
  34 //static const char     *csaDT_NAMES[] = {"DT_NULL", "DT_NEEDED", "DT_PLTRELSZ", "DT_PLTGOT", "DT_HASH", "DT_STRTAB", "DT_SYMTAB", "DT_RELA", "DT_RELASZ", "DT_RELAENT", "DT_STRSZ", "DT_SYMENT", "DT_INIT", "DT_FINI", "DT_SONAME", "DT_RPATH", "DT_SYMBOLIC", "DT_REL", "DT_RELSZ", "DT_RELENT", "DT_PLTREL", "DT_DEBUG", "DT_TEXTREL", "DT_JMPREL"};
  35 static const char       *csaR_NAMES[] = {"R_386_NONE", "R_386_32", "R_386_PC32", "R_386_GOT32", "R_386_PLT32", "R_386_COPY", "R_386_GLOB_DAT", "R_386_JMP_SLOT", "R_386_RELATIVE", "R_386_GOTOFF", "R_386_GOTPC", "R_386_LAST"};
  36 #endif
  37
  38 // === PROTOTYPES ===
  39 void    *ElfRelocate(void *Base, char **envp, const char *Filename);
  40  int    ElfGetSymbol(void *Base, const char *Name, void **Ret, size_t *Size);
  41 void    *Elf32Relocate(void *Base, char **envp, const char *Filename);
  42  int    Elf32GetSymbol(void *Base, const char *Name, void **Ret, size_t *Size);
  43  int    elf_doRelocate_386(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff);
  44  int    elf_doRelocate_arm(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff);
  45  int    elf_doRelocate_unk(uint32_t , uint32_t *, Elf32_Addr , int , int , const char *, intptr_t);
  46 #ifdef SUPPORT_ELF64
  47 int     _Elf64DoReloc_X86_64(void *Base, const char *strtab, Elf64_Sym *symtab, Elf64_Xword r_info, void *ptr, Elf64_Sxword addend);
  48 void    *Elf64Relocate(void *Base, char **envp, const char *Filename);
  49  int    Elf64GetSymbol(void *Base, const char *Name, void **Ret, size_t *Size);
  50 #endif
  51 uint32_t        ElfHashString(const char *name);
  52
  53 // === CODE ===
  54 /**
  55  * \fn int ElfRelocate(void *Base, char **envp, const char *Filename)
  56  * \brief Relocates a loaded ELF Executable
  57  */
  58 void *ElfRelocate(void *Base, char **envp, const char *Filename)
  59 {
  60         Elf32_Ehdr      *hdr = Base;
  61
  62         switch(hdr->e_ident[4])
  63         {
  64         case ELFCLASS32:
  65                 return Elf32Relocate(Base, envp, Filename);
  66 #ifdef SUPPORT_ELF64
  67         case ELFCLASS64:
  68                 return Elf64Relocate(Base, envp, Filename);
  69 #endif
  70         default:
  71                 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);
  72                 return NULL;
  73         }
  74 }
  75
  76 /**
  77  * \fn int ElfGetSymbol(Uint Base, const char *name, void **ret)
  78  */
  79 int ElfGetSymbol(void *Base, const char *Name, void **ret, size_t *Size)
  80 {
  81         Elf32_Ehdr      *hdr = Base;
  82
  83         switch(hdr->e_ident[4])
  84         {
  85         case ELFCLASS32:
  86                 return Elf32GetSymbol(Base, Name, ret, Size);
  87 #ifdef SUPPORT_ELF64
  88         case ELFCLASS64:
  89                 return Elf64GetSymbol(Base, Name, ret, Size);
  90 #endif
  91         default:
  92                 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);
  93                 return 0;
  94         }
  95 }
  96
  97 int elf_doRelocate_386(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type,
  98                 int bRela, const char *Sym, intptr_t iBaseDiff)
  99 {
 100         void    *symval;
 101         switch( type )
 102         {
 103         // Standard 32 Bit Relocation (S+A)
 104         case R_386_32:
 105                 if( !GetSymbol(Sym, &symval, NULL) )
 106                         return 1;
 107                 DEBUGS(" elf_doRelocate: R_386_32 *0x%x += %p('%s')",
 108                                 ptr, symval, Sym);
 109                 *ptr = (intptr_t)symval + addend;
 110                 break;
 111
 112         // 32 Bit Relocation wrt. Offset (S+A-P)
 113         case R_386_PC32:
 114                 DEBUGS(" elf_doRelocate: '%s'", Sym);
 115                 if( !GetSymbol(Sym, &symval, NULL) )    return 1;
 116                 DEBUGS(" elf_doRelocate: R_386_PC32 *0x%x = 0x%x + 0x%p - 0x%x",
 117                         ptr, *ptr, symval, (intptr_t)ptr );
 118                 *ptr = (intptr_t)symval + addend - (intptr_t)ptr;
 119                 //*ptr = val + addend - ((Uint)ptr - iBaseDiff);
 120                 break;
 121
 122         // Absolute Value of a symbol (S)
 123         case R_386_GLOB_DAT:
 124         case R_386_JMP_SLOT:
 125                 DEBUGS(" elf_doRelocate: '%s'", Sym);
 126                 if( !GetSymbol(Sym, &symval, NULL) )    return 1;
 127                 DEBUGS(" elf_doRelocate: %s *0x%x = %p", csaR_NAMES[type], ptr, symval);
 128                 *ptr = (intptr_t)symval;
 129                 break;
 130
 131         // Base Address (B+A)
 132         case R_386_RELATIVE:
 133                 DEBUGS(" elf_doRelocate: R_386_RELATIVE *0x%x = 0x%x + 0x%x", ptr, iBaseDiff, addend);
 134                 *ptr = iBaseDiff + addend;
 135                 break;
 136
 137         case R_386_COPY: {
 138                 size_t  size;
 139                 if( !GetSymbol(Sym, &symval, &size) )   return 1;
 140                 DEBUGS(" elf_doRelocate_386: R_386_COPY (%p, %p, %i)", ptr, symval, size);
 141                 memcpy(ptr, symval, size);
 142                 break; }
 143
 144         default:
 145                 SysDebug("elf_doRelocate_386: Unknown relocation %i", type);
 146                 return 2;
 147         }
 148         return 0;
 149 }
 150
 151 int elf_doRelocate_arm(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff)
 152 {
 153         uint32_t        val;
 154         switch(type)
 155         {
 156         // (S + A) | T
 157         case R_ARM_ABS32:
 158                 DEBUGS(" elf_doRelocate_arm: R_ARM_ABS32 %p (%s + %x)", ptr, Sym, addend);
 159                 if( !GetSymbol(Sym, (void**)&val, NULL) )       return 1;
 160                 *ptr = val + addend;
 161                 break;
 162         case R_ARM_GLOB_DAT:
 163                 DEBUGS(" elf_doRelocate_arm: R_ARM_GLOB_DAT %p (%s + %x)", ptr, Sym, addend);
 164                 if( !GetSymbol(Sym, (void**)&val, NULL) )       return 1;
 165                 *ptr = val + addend;
 166                 break;
 167         case R_ARM_JUMP_SLOT:
 168                 if(!bRela)      addend = 0;
 169                 DEBUGS(" elf_doRelocate_arm: R_ARM_JUMP_SLOT %p (%s + %x)", ptr, Sym, addend);
 170                 if( !GetSymbol(Sym, (void**)&val, NULL) )       return 1;
 171                 *ptr = val + addend;
 172                 break;
 173         // Copy
 174         case R_ARM_COPY: {
 175                 size_t  size;
 176                 void    *src;
 177                 if( !GetSymbol(Sym, &src, &size) )      return 1;
 178                 DEBUGS(" elf_doRelocate_arm: R_ARM_COPY (%p, %p, %i)", ptr, src, size);
 179                 memcpy(ptr, src, size);
 180                 break; }
 181         // Delta between link and runtime locations + A
 182         case R_ARM_RELATIVE:
 183                 DEBUGS(" elf_doRelocate_arm: R_ARM_RELATIVE %p (0x%x + 0x%x)", ptr, iBaseDiff, addend);
 184                 if(Sym[0] != '\0') {
 185                         // TODO: Get delta for a symbol
 186                         SysDebug("elf_doRelocate_arm: TODO - Implment R_ARM_RELATIVE for symbols");
 187                         return 2;
 188                 }
 189                 else {
 190                         *ptr = iBaseDiff + addend;
 191                 }
 192                 break;
 193         default:
 194                 SysDebug("elf_doRelocate_arm: Unknown Relocation, %i", type);
 195                 return 2;
 196         }
 197         return 0;
 198 }
 199
 200 int elf_doRelocate_unk(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, int bRela, const char *Sym, intptr_t iBaseDiff)
 201 {
 202         return 1;
 203 }
 204
 205 void *Elf32Relocate(void *Base, char **envp, const char *Filename)
 206 {
 207         Elf32_Ehdr      *hdr = Base;
 208         Elf32_Phdr      *phtab;
 209         char    *libPath;
 210         intptr_t        iRealBase = -1;
 211         intptr_t        iBaseDiff;
 212          int    iSegmentCount;
 213         Elf32_Rel       *rel = NULL;
 214         Elf32_Rela      *rela = NULL;
 215         void    *plt = NULL;
 216          int    relSz=0, relEntSz=8;
 217          int    relaSz=0, relaEntSz=8;
 218          int    pltSz=0, pltType=0;
 219         Elf32_Dyn       *dynamicTab = NULL;     // Dynamic Table Pointer
 220         char    *dynstrtab = NULL;      // .dynamic String Table
 221         Elf32_Sym       *dynsymtab;
 222         int     (*do_relocate)(uint32_t t_info, uint32_t *ptr, Elf32_Addr addend, int Type, int bRela, const char *Sym, intptr_t iBaseDiff);
 223
 224         DEBUGS("ElfRelocate: (Base=0x%x)", Base);
 225
 226         // Check magic header
 227
 228
 229         // Parse Program Header to get Dynamic Table
 230         phtab = (void*)( (uintptr_t)Base + hdr->phoff );
 231         iSegmentCount = hdr->phentcount;
 232         for(int i = 0; i < iSegmentCount; i ++)
 233         {
 234                 switch(phtab[i].Type)
 235                 {
 236                 case PT_LOAD:
 237                         // Determine linked base address
 238                         if( iRealBase > phtab[i].VAddr)
 239                                 iRealBase = phtab[i].VAddr;
 240                         break;
 241                 case PT_DYNAMIC:
 242                         // Find Dynamic Section
 243                         if(!dynamicTab) {
 244                                 dynamicTab = (void *) (intptr_t) phtab[i].VAddr;
 245                         }
 246                         else {
 247                                 DEBUGS(" WARNING - elf_relocate: Multiple PT_DYNAMIC segments");
 248                         }
 249                         break;
 250                 }
 251         }
 252
 253         // Page Align real base
 254         iRealBase &= ~0xFFF;
 255         DEBUGS(" elf_relocate: True Base = 0x%x, Compiled Base = 0x%x", Base, iRealBase);
 256
 257         // Adjust "Real" Base
 258         iBaseDiff = (intptr_t)Base - iRealBase;
 259
 260 //      hdr->entrypoint += iBaseDiff;   // Adjust Entrypoint
 261
 262         // Check if a PT_DYNAMIC segement was found
 263         if(!dynamicTab) {
 264                 SysDebug(" elf_relocate: No PT_DYNAMIC segment in image %p, returning", Base);
 265                 return (void *)(intptr_t)(hdr->entrypoint + iBaseDiff);
 266         }
 267
 268         // Allow writing to read-only segments, just in case they need to be relocated
 269         // - Will be reversed at the end of the function
 270         for( int i = 0; i < iSegmentCount; i ++ )
 271         {
 272                 if(phtab[i].Type == PT_LOAD && !(phtab[i].Flags & PF_W) ) {
 273                         uintptr_t       addr = phtab[i].VAddr + iBaseDiff;
 274                         uintptr_t       end = addr + phtab[i].MemSize;
 275                         for( ; addr < end; addr += PAGE_SIZE )
 276                                 _SysSetMemFlags(addr, 0, 1);    // Unset RO
 277                 }
 278         }
 279
 280         // Adjust Dynamic Table
 281         dynamicTab = (void *)( (intptr_t)dynamicTab + iBaseDiff );
 282
 283         // === Get Symbol table and String Table ===
 284         dynsymtab = NULL;
 285         for( int j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
 286         {
 287                 switch(dynamicTab[j].d_tag)
 288                 {
 289                 // --- Symbol Table ---
 290                 case DT_SYMTAB:
 291                         DEBUGS(" elf_relocate: DYNAMIC Symbol Table 0x%x (0x%x)",
 292                                 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
 293                         dynsymtab = (void*)((intptr_t)dynamicTab[j].d_val + iBaseDiff);
 294                         //if(iBaseDiff != 0)    dynamicTab[j].d_val += iBaseDiff;
 295                         break;
 296                 // --- String Table ---
 297                 case DT_STRTAB:
 298                         DEBUGS(" elf_relocate: DYNAMIC String Table 0x%x (0x%x)",
 299                                 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
 300                         dynstrtab = (void*)((intptr_t)dynamicTab[j].d_val + iBaseDiff);
 301                         //if(iBaseDiff != 0)    dynamicTab[j].d_val += iBaseDiff;
 302                         break;
 303                 // --- Hash Table --
 304                 case DT_HASH:
 305                         //if(iBaseDiff != 0)    dynamicTab[j].d_val += iBaseDiff;
 306 //                      iSymCount = ((Elf32_Word*)(intptr_t)dynamicTab[j].d_val)[1];
 307                         break;
 308                 }
 309         }
 310
 311         if(dynsymtab == NULL) {
 312                 SysDebug("ld-acess.so - WARNING: No Dynamic Symbol table in %p, returning", hdr);
 313                 return (void *)(intptr_t) (hdr->entrypoint + iBaseDiff);
 314         }
 315
 316         // === Add to loaded list (can be imported now) ===
 317         AddLoaded( Filename, Base );
 318
 319         // === Parse Relocation Data ===
 320         DEBUGS(" elf_relocate: dynamicTab = 0x%x", dynamicTab);
 321         for( int j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
 322         {
 323                 switch(dynamicTab[j].d_tag)
 324                 {
 325                 // --- Shared Library Name ---
 326                 case DT_SONAME:
 327                         DEBUGS(" elf_relocate: .so Name '%s'", dynstrtab+dynamicTab[j].d_val);
 328                         break;
 329                 // --- Needed Library ---
 330                 case DT_NEEDED:
 331                         libPath = dynstrtab + dynamicTab[j].d_val;
 332                         DEBUGS(" dynstrtab = %p, d_val = 0x%x", dynstrtab, dynamicTab[j].d_val);
 333                         DEBUGS(" Required Library '%s'", libPath);
 334                         if(LoadLibrary(libPath, NULL, envp) == 0) {
 335                                 #if DEBUG
 336                                 DEBUGS(" elf_relocate: Unable to load '%s'", libPath);
 337                                 #else
 338                                 SysDebug("Unable to load required library '%s'", libPath);
 339                                 #endif
 340                                 return 0;
 341                         }
 342                         DEBUGS(" Lib loaded");
 343                         break;
 344                 // --- PLT/GOT ---
 345 //              case DT_PLTGOT: pltgot = (void*)(iBaseDiff + dynamicTab[j].d_val);      break;
 346                 case DT_JMPREL: plt = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
 347                 case DT_PLTREL: pltType = dynamicTab[j].d_val;  break;
 348                 case DT_PLTRELSZ:       pltSz = dynamicTab[j].d_val;    break;
 349
 350                 // --- Relocation ---
 351                 case DT_REL:    rel = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
 352                 case DT_RELSZ:  relSz = dynamicTab[j].d_val;    break;
 353                 case DT_RELENT: relEntSz = dynamicTab[j].d_val; break;
 354                 case DT_RELA:   rela = (void*)(iBaseDiff + dynamicTab[j].d_val);        break;
 355                 case DT_RELASZ: relaSz = dynamicTab[j].d_val;   break;
 356                 case DT_RELAENT:        relaEntSz = dynamicTab[j].d_val;        break;
 357
 358                 // --- Symbol Table ---
 359                 case DT_SYMTAB:
 360                 // --- Hash Table ---
 361                 case DT_HASH:
 362                 // --- String Table ---
 363                 case DT_STRTAB:
 364                         break;
 365
 366                 // --- Unknown ---
 367                 default:
 368                         if(dynamicTab[j].d_tag > DT_JMPREL)     continue;
 369                         //DEBUGS(" elf_relocate: %i-%i = %s,0x%x",
 370                         //      i,j, csaDT_NAMES[dynamicTab[j].d_tag],dynamicTab[j].d_val);
 371                         break;
 372                 }
 373         }
 374
 375         DEBUGS(" elf_relocate: Beginning Relocation");
 376
 377          int    fail = 0;
 378
 379         switch(hdr->machine)
 380         {
 381         case EM_386:
 382                 do_relocate = elf_doRelocate_386;
 383                 break;
 384         case EM_ARM:
 385                 do_relocate = elf_doRelocate_arm;
 386                 break;
 387         default:
 388                 SysDebug("Elf32Relocate: Unknown machine type %i", hdr->machine);
 389                 do_relocate = elf_doRelocate_unk;
 390                 fail = 1;
 391                 break;
 392         }
 393
 394         DEBUGS("do_relocate = %p (%p or %p)", do_relocate, &elf_doRelocate_386, &elf_doRelocate_arm);
 395
 396         #define _doRelocate(r_info, ptr, bRela, addend) \
 397                 do_relocate(r_info, ptr, addend, ELF32_R_TYPE(r_info), bRela, \
 398                         dynstrtab + dynsymtab[ELF32_R_SYM(r_info)].nameOfs, iBaseDiff);
 399
 400         // Parse Relocation Entries
 401         if(rel && relSz)
 402         {
 403                 Elf32_Word      *ptr;
 404                 DEBUGS(" elf_relocate: rel=0x%x, relSz=0x%x, relEntSz=0x%x", rel, relSz, relEntSz);
 405                 int max = relSz / relEntSz;
 406                 for( int i = 0; i < max; i++ )
 407                 {
 408                         //DEBUGS("  Rel %i: 0x%x+0x%x", i, iBaseDiff, rel[i].r_offset);
 409                         ptr = (void*)(iBaseDiff + rel[i].r_offset);
 410                         fail |= _doRelocate(rel[i].r_info, ptr, 0, *ptr);
 411                 }
 412         }
 413         // Parse Relocation Entries
 414         if(rela && relaSz)
 415         {
 416                 Elf32_Word      *ptr;
 417                 DEBUGS(" elf_relocate: rela=0x%x, relaSz=0x%x, relaEntSz=0x%x", rela, relaSz, relaEntSz);
 418                 int count = relaSz / relaEntSz;
 419                 for( int i = 0; i < count; i++ )
 420                 {
 421                         ptr = (void*)(iBaseDiff + rela[i].r_offset);
 422                         fail |= _doRelocate(rel[i].r_info, ptr, 1, rela[i].r_addend);
 423                 }
 424         }
 425
 426         // === Process PLT (Procedure Linkage Table) ===
 427         if(plt && pltSz)
 428         {
 429                 Elf32_Word      *ptr;
 430                 DEBUGS(" elf_relocate: Relocate PLT, plt=0x%x", plt);
 431                 if(pltType == DT_REL)
 432                 {
 433                         Elf32_Rel       *pltRel = plt;
 434                         int count = pltSz / sizeof(Elf32_Rel);
 435                         DEBUGS(" elf_relocate: PLT Reloc Type = Rel, %i entries", count);
 436                         for(int i = 0; i < count; i ++)
 437                         {
 438                                 ptr = (void*)(iBaseDiff + pltRel[i].r_offset);
 439                                 fail |= _doRelocate(pltRel[i].r_info, ptr, 0, *ptr);
 440                         }
 441                 }
 442                 else
 443                 {
 444                         Elf32_Rela      *pltRela = plt;
 445                         int count = pltSz / sizeof(Elf32_Rela);
 446                         DEBUGS(" elf_relocate: PLT Reloc Type = Rela, %i entries", count);
 447                         for(int i=0;i<count;i++)
 448                         {
 449                                 ptr = (void*)(iRealBase + pltRela[i].r_offset);
 450                                 fail |= _doRelocate(pltRela[i].r_info, ptr, 1, pltRela[i].r_addend);
 451                         }
 452                 }
 453         }
 454
 455         // Re-set readonly
 456         for( int i = 0; i < iSegmentCount; i ++ )
 457         {
 458                 // If load and not writable
 459                 if(phtab[i].Type == PT_LOAD && !(phtab[i].Flags & PF_W) ) {
 460                         uintptr_t       addr = phtab[i].VAddr + iBaseDiff;
 461                         uintptr_t       end = addr + phtab[i].MemSize;
 462                         for( ; addr < end; addr += PAGE_SIZE )
 463                                 _SysSetMemFlags(addr, 1, 1);    // Unset RO
 464                 }
 465         }
 466
 467         if( fail ) {
 468                 DEBUGS("ElfRelocate: Failure");
 469                 return NULL;
 470         }
 471
 472         #undef _doRelocate
 473
 474         DEBUGS("ElfRelocate: RETURN 0x%x to %p", hdr->entrypoint + iBaseDiff, __builtin_return_address(0));
 475         return (void*)(intptr_t)( hdr->entrypoint + iBaseDiff );
 476 }
 477
 478 int Elf32GetSymbol(void *Base, const char *Name, void **ret, size_t *Size)
 479 {
 480         Elf32_Ehdr      *hdr = Base;
 481         Elf32_Sym       *symtab = NULL;
 482          int    nbuckets = 0;
 483         Elf32_Word      *pBuckets = NULL;
 484         Elf32_Word      *pChains;
 485         uint32_t        iNameHash;
 486         const char      *dynstrtab = NULL;
 487         uintptr_t       iBaseDiff = -1;
 488         Elf32_Phdr      *phtab;
 489         Elf32_Dyn       *dynTab = NULL;
 490
 491         // Locate the tables
 492         phtab = (void*)( (uintptr_t)Base + hdr->phoff );
 493         for( int i = 0; i < hdr->phentcount; i ++ )
 494         {
 495                 if(phtab[i].Type == PT_LOAD && iBaseDiff > phtab[i].VAddr)
 496                         iBaseDiff = phtab[i].VAddr;
 497                 if( phtab[i].Type == PT_DYNAMIC ) {
 498                         dynTab = (void*)(intptr_t)phtab[i].VAddr;
 499                 }
 500         }
 501         if( !dynTab ) {
 502                 SysDebug("ERROR - Unable to find DYNAMIC segment in %p", Base);
 503                 return 0;
 504         }
 505         iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
 506         dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
 507         for( int i = 0; dynTab[i].d_tag != DT_NULL; i++)
 508         {
 509                 switch(dynTab[i].d_tag)
 510                 {
 511                 // --- Symbol Table ---
 512                 case DT_SYMTAB:
 513                         symtab = (void*)((intptr_t)dynTab[i].d_val + iBaseDiff);        // Rebased in Relocate
 514                         break;
 515                 case DT_STRTAB:
 516                         dynstrtab = (void*)((intptr_t)dynTab[i].d_val + iBaseDiff);
 517                         break;
 518                 // --- Hash Table --
 519                 case DT_HASH:
 520                         pBuckets = (void*)((intptr_t)dynTab[i].d_val + iBaseDiff);
 521                         break;
 522                 }
 523         }
 524
 525         if( !symtab ) {
 526                 SysDebug("ERRO - No DT_SYMTAB in %p", Base);
 527                 return 0;
 528         }
 529         if( !pBuckets ) {
 530                 SysDebug("ERRO - No DT_HASH in %p", Base);
 531                 return 0;
 532         }
 533         if( !dynstrtab ) {
 534                 SysDebug("ERRO - No DT_STRTAB in %p", Base);
 535                 return 0;
 536         }
 537
 538         // ... ok... maybe they haven't been relocated
 539         if( (uintptr_t)symtab < (uintptr_t)Base )
 540         {
 541                 symtab    = (void*)( (uintptr_t)symtab    + iBaseDiff );
 542                 pBuckets  = (void*)( (uintptr_t)pBuckets  + iBaseDiff );
 543                 dynstrtab = (void*)( (uintptr_t)dynstrtab + iBaseDiff );
 544                 SysDebug("Executable not yet relocated");
 545         }
 546
 547         nbuckets = pBuckets[0];
 548 //      iSymCount = pBuckets[1];
 549         pBuckets = &pBuckets[2];
 550         pChains = &pBuckets[ nbuckets ];
 551         assert(pChains);
 552
 553         // Get hash
 554         iNameHash = ElfHashString(Name);
 555         iNameHash %= nbuckets;
 556
 557         // Walk Chain
 558         int idx = pBuckets[ iNameHash ];
 559         do {
 560                 Elf32_Sym *sym = &symtab[idx];
 561                 assert(sym);
 562                 if(sym->shndx != SHN_UNDEF && strcmp(dynstrtab + sym->nameOfs, Name) == 0) {
 563                         *ret = (void*)( (uintptr_t)sym->value + iBaseDiff );
 564                         if(Size)        *Size = sym->size;
 565                         return 1;
 566                 }
 567         } while( (idx = pChains[idx]) != STN_UNDEF && idx != pBuckets[iNameHash] );
 568
 569         return 0;
 570 }
 571
 572 #ifdef SUPPORT_ELF64
 573 typedef int (*t_elf64_doreloc)(void *Base, const char *strtab, Elf64_Sym *symtab, Elf64_Xword r_info, void *ptr, Elf64_Sxword addend);
 574
 575 int _Elf64DoReloc_X86_64(void *Base, const char *strtab, Elf64_Sym *symtab, Elf64_Xword r_info, void *ptr, Elf64_Sxword addend)
 576 {
 577          int    sym = ELF64_R_SYM(r_info);
 578          int    type = ELF64_R_TYPE(r_info);
 579         const char      *symname = strtab + symtab[sym].st_name;
 580         void    *symval;
 581         //DEBUGS("_Elf64DoReloc: %s", symname);
 582         switch( type )
 583         {
 584         case R_X86_64_NONE:
 585                 break;
 586         case R_X86_64_64:
 587                 if( !GetSymbol(symname, &symval, NULL)  )       return 1;
 588                 *(uint64_t*)ptr = (uintptr_t)symval + addend;
 589                 break;
 590         case R_X86_64_COPY: {
 591                 size_t  size;
 592                 if( !GetSymbol(symname, &symval, &size)  )      return 1;
 593                 memcpy(ptr, symval, size);
 594                 } break;
 595         case R_X86_64_GLOB_DAT:
 596                 if( !GetSymbol(symname, &symval, NULL)  )       return 1;
 597                 *(uint64_t*)ptr = (uintptr_t)symval;
 598                 break;
 599         case R_X86_64_JUMP_SLOT:
 600                 if( !GetSymbol(symname, &symval, NULL)  )       return 1;
 601                 *(uint64_t*)ptr = (uintptr_t)symval;
 602                 break;
 603         case R_X86_64_RELATIVE:
 604                 *(uint64_t*)ptr = (uintptr_t)Base + addend;
 605                 break;
 606         default:
 607                 SysDebug("ld-acess - _Elf64DoReloc: Unknown relocation type %i", type);
 608                 return 2;
 609         }
 610         //DEBUGS("_Elf64DoReloc: - Good");
 611         return 0;
 612 }
 613
 614 void *Elf64Relocate(void *Base, char **envp, const char *Filename)
 615 {
 616          int    i;
 617         Elf64_Ehdr      *hdr = Base;
 618         Elf64_Phdr      *phtab;
 619         Elf64_Dyn       *dyntab = NULL;
 620         Elf64_Addr      compiledBase = -1, baseDiff;
 621         Elf64_Sym       *symtab = NULL;
 622         char    *strtab = NULL;
 623         Elf64_Word      *hashtab = NULL;
 624         Elf64_Rel       *rel = NULL;
 625          int    rel_count = 0;
 626         Elf64_Rela      *rela = NULL;
 627          int    rela_count = 0;
 628         void    *pltrel = NULL;
 629          int    plt_size = 0, plt_type = 0;
 630
 631         DEBUGS("Elf64Relocate: hdr = {");
 632         DEBUGS("Elf64Relocate:  e_ident = '%.16s'", hdr->e_ident);
 633         DEBUGS("Elf64Relocate:  e_type = 0x%x", hdr->e_type);
 634         DEBUGS("Elf64Relocate:  e_machine = 0x%x", hdr->e_machine);
 635         DEBUGS("Elf64Relocate:  e_version = 0x%x", hdr->e_version);
 636         DEBUGS("Elf64Relocate:  e_entry = %p", hdr->e_entry);
 637         DEBUGS("Elf64Relocate:  e_phoff = 0x%llx", hdr->e_phoff);
 638         DEBUGS("Elf64Relocate:  e_shoff = 0x%llx", hdr->e_shoff);
 639         DEBUGS("Elf64Relocate:  e_flags = 0x%x", hdr->e_flags);
 640         DEBUGS("Elf64Relocate:  e_ehsize = 0x%x", hdr->e_ehsize);
 641         DEBUGS("Elf64Relocate:  e_phentsize = 0x%x", hdr->e_phentsize);
 642         DEBUGS("Elf64Relocate:  e_phnum = %i", hdr->e_phnum);
 643
 644         // Scan for the dynamic table (and find the compiled base)
 645         phtab = (void*)((uintptr_t)Base + (uintptr_t)hdr->e_phoff);
 646         for( i = 0; i < hdr->e_phnum; i ++ )
 647         {
 648                 if(phtab[i].p_type == PT_DYNAMIC)
 649                         dyntab = (void *)(intptr_t)phtab[i].p_vaddr;
 650                 if(phtab[i].p_type == PT_LOAD && compiledBase > phtab[i].p_vaddr)
 651                         compiledBase = phtab[i].p_vaddr;
 652         }
 653
 654         baseDiff = (uintptr_t)Base - compiledBase;
 655
 656         DEBUGS("baseDiff = %p", baseDiff);
 657
 658         if(dyntab == NULL) {
 659                 SysDebug(" Elf64Relocate: No PT_DYNAMIC segment in image %p, returning", Base);
 660                 return (void *)(uintptr_t)(hdr->e_entry + baseDiff);
 661         }
 662
 663         dyntab = (void *)(uintptr_t)((uintptr_t)dyntab + baseDiff);
 664
 665         // Parse the dynamic table (first pass)
 666         // - Search for String, Symbol and Hash tables
 667         for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
 668         {
 669                 switch(dyntab[i].d_tag)
 670                 {
 671                 case DT_SYMTAB:
 672                         dyntab[i].d_un.d_ptr += baseDiff;
 673                         symtab = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;
 674                         break;
 675                 case DT_STRTAB:
 676                         dyntab[i].d_un.d_ptr += baseDiff;
 677                         strtab = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;
 678                         break;
 679                 case DT_HASH:
 680                         dyntab[i].d_un.d_ptr += baseDiff;
 681                         hashtab = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;
 682                         break;
 683                 }
 684         }
 685
 686         if( !symtab || !strtab || !hashtab ) {
 687                 SysDebug("ld-acess - Elf64Relocate: Missing Symbol, string or hash table");
 688                 return NULL;
 689         }
 690
 691         // Ready for symbol use
 692         AddLoaded( Filename, Base );
 693
 694         // Second pass on dynamic table
 695         for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
 696         {
 697                 DEBUGS("dyntab[%i].d_tag = %i", i, dyntab[i].d_tag);
 698                 switch(dyntab[i].d_tag)
 699                 {
 700                 case DT_SONAME: break;
 701
 702                 case DT_NEEDED: {
 703                         char *libPath = strtab + dyntab[i].d_un.d_val;
 704                         DEBUGS("Elf64Relocate: libPath = '%s'", libPath);
 705                         if(LoadLibrary(libPath, NULL, envp) == 0) {
 706                                 SysDebug("ld-acess - Elf64Relocate: Unable to load '%s'", libPath);
 707                                 return NULL;
 708                         }
 709                         } break;
 710
 711                 // Relocation entries
 712                 case DT_REL:
 713                         dyntab[i].d_un.d_ptr += baseDiff;
 714                         rel = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;
 715                         break;
 716                 case DT_RELSZ:
 717                         rel_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rel);
 718                         break;
 719                 case DT_RELENT:
 720                         if( dyntab[i].d_un.d_val != sizeof(Elf64_Rel) ) {
 721                                 SysDebug("ld-acess - Elf64Relocate: DT_RELENT(%i) != sizeof(Elf64_Rel)(%i)",
 722                                         dyntab[i].d_un.d_val, sizeof(Elf64_Rel));
 723                                 return NULL;
 724                         }
 725                         break;
 726                 case DT_RELA:
 727                         dyntab[i].d_un.d_ptr += baseDiff;
 728                         rela = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;
 729                         break;
 730                 case DT_RELASZ:
 731                         rela_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rela);
 732                         break;
 733                 case DT_RELAENT:
 734                         if( dyntab[i].d_un.d_val != sizeof(Elf64_Rela) ) {
 735                                 SysDebug("ld-acess - Elf64Relocate: DT_RELAENT(%i) != sizeof(Elf64_Rela)(%i)",
 736                                         dyntab[i].d_un.d_val, sizeof(Elf64_Rela));
 737                                 return NULL;
 738                         }
 739                         break;
 740                 case DT_JMPREL:
 741                         dyntab[i].d_un.d_ptr += baseDiff;
 742                         pltrel = (void *)(uintptr_t)dyntab[i].d_un.d_ptr;
 743                         break;
 744                 case DT_PLTREL:
 745                         plt_type = dyntab[i].d_un.d_val;
 746                         break;
 747                 case DT_PLTRELSZ:
 748                         plt_size = dyntab[i].d_un.d_val;
 749                         break;
 750                 }
 751         }
 752
 753         // Relocation function
 754         t_elf64_doreloc fpElf64DoReloc = &_Elf64DoReloc_X86_64;
 755         #define _Elf64DoReloc(info, ptr, addend)        fpElf64DoReloc(Base, strtab, symtab, info, ptr, addend)
 756
 757         int fail = 0;
 758         if( rel )
 759         {
 760                 DEBUGS("rel_count = %i", rel_count);
 761                 for( i = 0; i < rel_count; i ++ )
 762                 {
 763                         uint64_t *ptr = (void *)(uintptr_t)( rel[i].r_offset + baseDiff );
 764                         fail |= _Elf64DoReloc( rel[i].r_info, ptr, *ptr);
 765                 }
 766         }
 767
 768         if( rela )
 769         {
 770                 DEBUGS("rela_count = %i", rela_count);
 771                 for( i = 0; i < rela_count; i ++ )
 772                 {
 773                         uint64_t *ptr = (void *)(uintptr_t)( rela[i].r_offset + baseDiff );
 774                         fail |= _Elf64DoReloc( rela[i].r_info, ptr, rela[i].r_addend );
 775                 }
 776         }
 777
 778         if( pltrel && plt_type )
 779         {
 780                 if( plt_type == DT_REL ) {
 781                         Elf64_Rel       *plt = pltrel;
 782                          int    count = plt_size / sizeof(Elf64_Rel);
 783                         DEBUGS("plt rel count = %i", count);
 784                         for( i = 0; i < count; i ++ )
 785                         {
 786                                 uint64_t *ptr = (void *)(uintptr_t)( plt[i].r_offset + baseDiff );
 787                                 fail |= _Elf64DoReloc( plt[i].r_info, ptr, *ptr);
 788                         }
 789                 }
 790                 else {
 791                         Elf64_Rela      *plt = pltrel;
 792                          int    count = plt_size / sizeof(Elf64_Rela);
 793                         DEBUGS("plt rela count = %i", count);
 794                         for( i = 0; i < count; i ++ )
 795                         {
 796                                 uint64_t *ptr = (void *)(uintptr_t)( plt[i].r_offset + baseDiff );
 797                                 fail |= _Elf64DoReloc( plt[i].r_info, ptr, plt[i].r_addend);
 798                         }
 799                 }
 800         }
 801
 802         if( fail ) {
 803                 DEBUGS("Elf64Relocate: Failure");
 804                 return NULL;
 805         }
 806
 807         {
 808         void *ret = (void *)(uintptr_t)(hdr->e_entry + baseDiff);
 809         DEBUGS("Elf64Relocate: Relocations done, return %p", ret);
 810         return ret;
 811         }
 812 }
 813
 814 int Elf64GetSymbol(void *Base, const char *Name, void **Ret, size_t *Size)
 815 {
 816         Elf64_Ehdr      *hdr = Base;
 817         Elf64_Sym       *symtab;
 818          int    nbuckets = 0;
 819 //       int    iSymCount = 0;
 820          int    i;
 821         Elf64_Word      *pBuckets;
 822         Elf64_Word      *pChains;
 823         uint32_t        iNameHash;
 824         const char      *dynstrtab;
 825         uintptr_t       iBaseDiff = -1;
 826
 827         dynstrtab = NULL;
 828         pBuckets = NULL;
 829         symtab = NULL;
 830
 831         // Catch the current executable
 832         if( !pBuckets )
 833         {
 834                 Elf64_Phdr      *phtab;
 835                 Elf64_Dyn       *dynTab = NULL;
 836                  int    j;
 837
 838                 // Locate the tables
 839                 phtab = (void*)( (intptr_t)Base + (uintptr_t)hdr->e_phoff );
 840                 for( i = 0; i < hdr->e_phnum; i ++ )
 841                 {
 842                         if(phtab[i].p_type == PT_LOAD && iBaseDiff > phtab[i].p_vaddr)
 843                                 iBaseDiff = phtab[i].p_vaddr;
 844                         if( phtab[i].p_type == PT_DYNAMIC ) {
 845                                 dynTab = (void*)(intptr_t)phtab[i].p_vaddr;
 846                         }
 847                 }
 848                 if( !dynTab ) {
 849                         SysDebug("ERROR - Unable to find DYNAMIC segment in %p", Base);
 850                         return 0;
 851                 }
 852                 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
 853                 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
 854
 855                 for( j = 0; dynTab[j].d_tag != DT_NULL; j++)
 856                 {
 857                         switch(dynTab[j].d_tag)
 858                         {
 859                         // --- Symbol Table ---
 860                         case DT_SYMTAB:
 861                                 symtab = (void*)(intptr_t) dynTab[j].d_un.d_val;        // Rebased in Relocate
 862                                 break;
 863                         case DT_STRTAB:
 864                                 dynstrtab = (void*)(intptr_t) dynTab[j].d_un.d_val;
 865                                 break;
 866                         // --- Hash Table --
 867                         case DT_HASH:
 868                                 pBuckets = (void*)(intptr_t) dynTab[j].d_un.d_val;
 869                                 break;
 870                         }
 871                 }
 872         }
 873
 874         nbuckets = pBuckets[0];
 875 //      iSymCount = pBuckets[1];
 876         pBuckets = &pBuckets[2];
 877         pChains = &pBuckets[ nbuckets ];
 878
 879         // Get hash
 880         iNameHash = ElfHashString(Name);
 881         iNameHash %= nbuckets;
 882
 883         // Walk Chain
 884         i = pBuckets[ iNameHash ];
 885         if(symtab[i].st_shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].st_name, Name) == 0) {
 886                 *Ret = (void*)( (intptr_t)symtab[i].st_value + iBaseDiff );
 887                 if(Size)        *Size = symtab[i].st_size;
 888                 DEBUGS("%s = %p", Name, *Ret);
 889                 return 1;
 890         }
 891
 892         while(pChains[i] != STN_UNDEF)
 893         {
 894                 i = pChains[i];
 895                 if(symtab[i].st_shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].st_name, Name) == 0) {
 896                         *Ret = (void*)((intptr_t)symtab[i].st_value + iBaseDiff);
 897                         if(Size)        *Size = symtab[i].st_size;
 898                         DEBUGS("%s = %p", Name, *Ret);
 899                         return 1;
 900                 }
 901         }
 902
 903         return 0;
 904 }
 905 #endif
 906
 907
 908 uint32_t ElfHashString(const char *name)
 909 {
 910         uint32_t        h = 0, g;
 911         while(*name)
 912         {
 913                 h = (h << 4) + *(uint8_t*)name++;
 914                 if( (g = h & 0xf0000000) )
 915                         h ^= g >> 24;
 916                 h &= ~g;
 917         }
 918         return h;
 919 }
 920