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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 | /* * Copyright (c) 2021 Apple Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this * file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_LICENSE_HEADER_END@ */ #include <sys/types.h> #include <assert.h> #include <limits.h> #include <stdlib.h> #include <string.h> #include <mach-o/loader.h> #include <mach-o/nlist.h> #include "Array.h" #include "RebaseOpcodes.h" #include "Misc.h" #include "Image.h" using dyld3::Array; namespace mach_o { // // MARK: --- RebaseOpcodes inspection methods --- // RebaseOpcodes::RebaseOpcodes(const uint8_t* start, size_t size, bool is64) : _opcodesStart(start), _opcodesEnd(start+size), _pointerSize(is64 ? 8 : 4) { } Error RebaseOpcodes::valid(std::span<const MappedSegment> segments, bool allowTextFixups, bool onlyFixupsInWritableSegments) const { __block Error locError; Error opcodeErr = this->forEachRebase(^(const char* opcodeName, int type, bool segIndexSet, uint8_t segmentIndex, uint64_t segmentOffset, bool& stop) { if ( !segIndexSet ) { locError = Error("%s missing preceding REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB", opcodeName); stop = true; } else if ( segmentIndex >= segments.size() ) { locError = Error("%s segment index %d too large", opcodeName, segmentIndex); stop = true; } else if ( segmentOffset > (segments[segmentIndex].runtimeSize-_pointerSize) ) { locError = Error("%s segment offset 0x%08llX beyond segment '%.*s' size (0x%08llX)", opcodeName, segmentOffset, (int)segments[segmentIndex].segName.size(), segments[segmentIndex].segName.data(), segments[segmentIndex].runtimeSize); stop = true; } else { switch ( type ) { case REBASE_TYPE_POINTER: if ( !segments[segmentIndex].writable && onlyFixupsInWritableSegments ) { locError = Error("%s pointer rebase is in non-writable segment '%.*s'", opcodeName, (int)segments[segmentIndex].segName.size(), segments[segmentIndex].segName.data()); stop = true; } else if ( segments[segmentIndex].executable && onlyFixupsInWritableSegments ) { locError = Error("%s pointer rebase is in executable segment '%.*s'", opcodeName, (int)segments[segmentIndex].segName.size(), segments[segmentIndex].segName.data()); stop = true; } break; case REBASE_TYPE_TEXT_ABSOLUTE32: case REBASE_TYPE_TEXT_PCREL32: if ( !allowTextFixups ) { locError = Error("%s text rebase not supported for architecture", opcodeName); stop = true; } else if ( segments[segmentIndex].writable ) { locError = Error("%s text rebase is in writable segment '%.*s'", opcodeName, (int)segments[segmentIndex].segName.size(), segments[segmentIndex].segName.data()); stop = true; } else if ( !segments[segmentIndex].executable ) { locError = Error("%s text rebase is in non-executable segment '%.*s'", opcodeName, (int)segments[segmentIndex].segName.size(), segments[segmentIndex].segName.data()); stop = true; } break; default: locError = Error("%s unknown rebase type", opcodeName); stop = true; } } }); if ( opcodeErr ) return opcodeErr; return std::move(locError); } Error RebaseOpcodes::forEachRebase(void (^handler)(const char* opcodeName, int type, bool segIndexSet, uint8_t segmentIndex, uint64_t segmentOffset, bool& stop)) const { const uint8_t* p = _opcodesStart; int type = 0; int segIndex = 0; uint64_t segOffset = 0; bool segIndexSet = false; bool stop = false; bool malformed = false; uint64_t count; uint64_t skip; while ( !stop && !malformed && (p < _opcodesEnd) ) { uint8_t immediate = *p & REBASE_IMMEDIATE_MASK; uint8_t opcode = *p & REBASE_OPCODE_MASK; ++p; switch (opcode) { case REBASE_OPCODE_DONE: // Allow some padding, in case rebases were somehow aligned to 16-bytes in size if ( (_opcodesEnd - p) > 15 ) return Error("rebase opcodes terminated early at offset %d of %d", (int)(p-_opcodesStart), (int)(_opcodesEnd-_opcodesStart)); break; case REBASE_OPCODE_SET_TYPE_IMM: switch ( immediate ) { case REBASE_TYPE_POINTER: case REBASE_TYPE_TEXT_ABSOLUTE32: case REBASE_TYPE_TEXT_PCREL32: type = immediate; break; default: type = 0; break; } break; case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: segIndex = immediate; segOffset = read_uleb128(p, _opcodesEnd, malformed); segIndexSet = true; break; case REBASE_OPCODE_ADD_ADDR_ULEB: segOffset += read_uleb128(p, _opcodesEnd, malformed); break; case REBASE_OPCODE_ADD_ADDR_IMM_SCALED: segOffset += immediate*_pointerSize; break; case REBASE_OPCODE_DO_REBASE_IMM_TIMES: for (int i=0; i < immediate; ++i) { handler("REBASE_OPCODE_DO_REBASE_IMM_TIMES", type, segIndexSet, segIndex, segOffset, stop); segOffset += _pointerSize; if ( stop ) break; } break; case REBASE_OPCODE_DO_REBASE_ULEB_TIMES: count = read_uleb128(p, _opcodesEnd, malformed); if ( malformed ) break; for (uint32_t i=0; i < count; ++i) { handler("REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB", type, segIndexSet, segIndex, segOffset, stop); segOffset += _pointerSize; if ( stop ) break; } break; case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB: handler("REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB", type, segIndexSet, segIndex, segOffset, stop); segOffset += read_uleb128(p, _opcodesEnd, malformed) + _pointerSize; break; case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB: count = read_uleb128(p, _opcodesEnd, malformed); if ( malformed ) break; skip = read_uleb128(p, _opcodesEnd, malformed); if ( malformed ) break; for (uint32_t i=0; i < count; ++i) { handler("REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB", type, segIndexSet, segIndex, segOffset, stop); segOffset += skip + _pointerSize; if ( stop ) break; } break; default: return Error("unknown rebase opcode 0x%02X", opcode); } } if ( malformed ) return Error("malformed uleb128"); else return Error::none(); } void RebaseOpcodes::forEachRebaseLocation(void (^callback)(uint32_t segIndex, uint64_t segOffset, bool& stop)) const { (void)forEachRebase(^(const char* opcodeName, int type, bool segIndexSet, uint8_t segmentIndex, uint64_t segmentOffset, bool& stop) { callback(segmentIndex, segmentOffset, stop); }); } void RebaseOpcodes::forEachRebaseLocation(std::span<const MappedSegment> segments, uint64_t prefLoadAdder, void (^callback)(const Fixup& fixup, bool& stop)) const { const bool is64 = (_pointerSize == 8); (void)forEachRebase(^(const char* opcodeName, int type, bool segIndexSet, uint8_t segIndex, uint64_t segOffset, bool& stop) { uint8_t* loc = (uint8_t*)(segments[segIndex].content) + segOffset; uint64_t targetVmOffset = (is64 ? *((uint64_t*)loc) : *((uint32_t*)loc)) - prefLoadAdder; Fixup fixup(loc, &segments[segIndex], targetVmOffset); callback(fixup, stop); }); } const uint8_t* RebaseOpcodes::bytes(size_t& size) const { size = (_opcodesEnd - _opcodesStart); return _opcodesStart; } void RebaseOpcodes::printOpcodes(FILE* output, int indentCount) const { uint8_t type = 0; uint64_t count; uint64_t skip; uint32_t segmentIndex; uint64_t segOffset; bool done = false; bool malformed = false; char indent[indentCount+1]; const uint8_t* p = _opcodesStart; for (int i=0; i < indentCount; ++i) indent[i] = ' '; indent[indentCount] = '\0'; while ( !done && !malformed && (p < _opcodesEnd) ) { uint8_t immediate = *p & REBASE_IMMEDIATE_MASK; uint8_t opcode = *p & REBASE_OPCODE_MASK; long opcodeOffset = p - _opcodesStart; ++p; switch (opcode) { case REBASE_OPCODE_DONE: done = true; fprintf(output, "%s0x%04lX REBASE_OPCODE_DONE()\n", indent, opcodeOffset); break; case REBASE_OPCODE_SET_TYPE_IMM: type = immediate; fprintf(output, "%s0x%04lX REBASE_OPCODE_SET_TYPE_IMM(%d)\n", indent, opcodeOffset, type); break; case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: segmentIndex = immediate; segOffset = read_uleb128(p, _opcodesEnd, malformed); fprintf(output, "%s0x%04lX REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB(%d, 0x%08llX)\n", indent, opcodeOffset, segmentIndex, segOffset); break; case REBASE_OPCODE_ADD_ADDR_ULEB: segOffset = read_uleb128(p, _opcodesEnd, malformed); fprintf(output, "%s0x%04lX REBASE_OPCODE_ADD_ADDR_ULEB(0x%0llX)\n", indent, opcodeOffset, segOffset); break; case REBASE_OPCODE_ADD_ADDR_IMM_SCALED: segOffset = immediate * _pointerSize; fprintf(output, "%s0x%04lX REBASE_OPCODE_ADD_ADDR_IMM_SCALED(0x%0llX)\n", indent, opcodeOffset, segOffset); break; case REBASE_OPCODE_DO_REBASE_IMM_TIMES: fprintf(output, "%s0x%04lX REBASE_OPCODE_DO_REBASE_IMM_TIMES(%d)\n", indent, opcodeOffset, immediate); break; case REBASE_OPCODE_DO_REBASE_ULEB_TIMES: count = read_uleb128(p, _opcodesEnd, malformed); fprintf(output, "%s0x%04lX REBASE_OPCODE_DO_REBASE_ULEB_TIMES(%lld)\n", indent, opcodeOffset, count); break; case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB: skip = read_uleb128(p, _opcodesEnd, malformed) + _pointerSize; fprintf(output, "%s0x%04lX REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB(%lld)\n", indent, opcodeOffset, skip); break; case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB: count = read_uleb128(p, _opcodesEnd, malformed); skip = read_uleb128(p, _opcodesEnd, malformed); fprintf(output, "%s0x%04lX REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB(%lld, %lld)\n", indent, opcodeOffset, count, skip); break; default: fprintf(output, "%sunknown rebase opcode 0x%02X\n", indent, *p); } } } #if BUILDING_MACHO_WRITER void RebaseOpcodes::append_uleb128(uint64_t value) { uint8_t byte; do { byte = value & 0x7F; value &= ~0x7F; if ( value != 0 ) byte |= 0x80; _opcodes.push_back(byte); value = value >> 7; } while( byte >= 0x80 ); } void RebaseOpcodes::append_byte(uint8_t value) { _opcodes.push_back(value); } RebaseOpcodes::RebaseOpcodes(std::span<const Location> sortedLocs, bool is64) : _opcodesStart(nullptr), _opcodesEnd(nullptr), _pointerSize(is64 ? 8 : 4) { if ( sortedLocs.empty() ) return; struct RebaseTmp { RebaseTmp(uint8_t op, uint64_t p1, uint64_t p2=0) : opcode(op), operand1(p1), operand2(p2) {} uint8_t opcode; uint64_t operand1; uint64_t operand2; }; // convert to temp encoding that can be more easily optimized std::vector<RebaseTmp> mid; uint32_t curSegIndex = 0; uint64_t curSegOffset = -1; mid.emplace_back(REBASE_OPCODE_SET_TYPE_IMM, REBASE_TYPE_POINTER); for (const Location& loc : sortedLocs) { if ( curSegIndex != loc.segIndex ) { mid.emplace_back(REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB, loc.segIndex, loc.segOffset); curSegIndex = loc.segIndex; curSegOffset = loc.segOffset; } else if ( curSegOffset != loc.segOffset ) { mid.emplace_back(REBASE_OPCODE_ADD_ADDR_ULEB, loc.segOffset - curSegOffset); curSegOffset = loc.segOffset; } mid.emplace_back(REBASE_OPCODE_DO_REBASE_ULEB_TIMES, 1); curSegOffset += _pointerSize; } mid.emplace_back(REBASE_OPCODE_DONE, 0); // optimize phase 1, compress packed runs of pointers RebaseTmp* dst = &mid[0]; for (const RebaseTmp* src = &mid[0]; src->opcode != REBASE_OPCODE_DONE; ++src) { if ( (src->opcode == REBASE_OPCODE_DO_REBASE_ULEB_TIMES) && (src->operand1 == 1) ) { *dst = *src++; while (src->opcode == REBASE_OPCODE_DO_REBASE_ULEB_TIMES ) { dst->operand1 += src->operand1; ++src; } --src; ++dst; } else { *dst++ = *src; } } dst->opcode = REBASE_OPCODE_DONE; // optimize phase 2, combine rebase/add pairs dst = &mid[0]; for (const RebaseTmp* src = &mid[0]; src->opcode != REBASE_OPCODE_DONE; ++src) { if ( (src->opcode == REBASE_OPCODE_DO_REBASE_ULEB_TIMES) && (src->operand1 == 1) && (src[1].opcode == REBASE_OPCODE_ADD_ADDR_ULEB)) { dst->opcode = REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB; dst->operand1 = src[1].operand1; ++src; ++dst; } else { *dst++ = *src; } } dst->opcode = REBASE_OPCODE_DONE; // optimize phase 3, compress packed runs of REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB with // same addr delta into one REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB dst = &mid[0]; for (const RebaseTmp* src = &mid[0]; src->opcode != REBASE_OPCODE_DONE; ++src) { uint64_t delta = src->operand1; if ( (src->opcode == REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB) && (src[1].opcode == REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB) && (src[2].opcode == REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB) && (src[1].operand1 == delta) && (src[2].operand1 == delta) ) { // found at least three in a row, this is worth compressing dst->opcode = REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB; dst->operand1 = 1; dst->operand2 = delta; ++src; while ( (src->opcode == REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB) && (src->operand1 == delta) ) { dst->operand1++; ++src; } --src; ++dst; } else { *dst++ = *src; } } dst->opcode = REBASE_OPCODE_DONE; // optimize phase 4, use immediate encodings for (RebaseTmp* p = &mid[0]; p->opcode != REBASE_OPCODE_DONE; ++p) { if ( (p->opcode == REBASE_OPCODE_ADD_ADDR_ULEB) && (p->operand1 < (15*_pointerSize)) && ((p->operand1 % _pointerSize) == 0) ) { p->opcode = REBASE_OPCODE_ADD_ADDR_IMM_SCALED; p->operand1 = p->operand1/_pointerSize; } else if ( (p->opcode == REBASE_OPCODE_DO_REBASE_ULEB_TIMES) && (p->operand1 < 15) ) { p->opcode = REBASE_OPCODE_DO_REBASE_IMM_TIMES; } } // convert to compressed encoding _opcodes.reserve(256); bool done = false; for (const RebaseTmp& r : mid) { switch ( r.opcode ) { case REBASE_OPCODE_DONE: done = true; break; case REBASE_OPCODE_SET_TYPE_IMM: append_byte(REBASE_OPCODE_SET_TYPE_IMM | r.operand1); break; case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: append_byte(REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB | r.operand1); append_uleb128(r.operand2); break; case REBASE_OPCODE_ADD_ADDR_ULEB: append_byte(REBASE_OPCODE_ADD_ADDR_ULEB); append_uleb128(r.operand1); break; case REBASE_OPCODE_ADD_ADDR_IMM_SCALED: append_byte(REBASE_OPCODE_ADD_ADDR_IMM_SCALED | r.operand1 ); break; case REBASE_OPCODE_DO_REBASE_IMM_TIMES: append_byte(REBASE_OPCODE_DO_REBASE_IMM_TIMES | r.operand1); break; case REBASE_OPCODE_DO_REBASE_ULEB_TIMES: append_byte(REBASE_OPCODE_DO_REBASE_ULEB_TIMES); append_uleb128(r.operand1); break; case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB: append_byte(REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB); append_uleb128(r.operand1); break; case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB: append_byte(REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB); append_uleb128(r.operand1); append_uleb128(r.operand2); break; } if ( done ) break; } // align to pointer size while ( (_opcodes.size() % _pointerSize) != 0 ) append_byte(0); _opcodesStart = &_opcodes[0]; _opcodesEnd = &_opcodes[_opcodes.size()]; } #endif // BUILDING_MACHO_WRITER } // namespace mach_o |