Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 1 | // Copyright 2011 Google Inc. All Rights Reserved. |
| 2 | |
jeffhao | ba5ebb9 | 2011-08-25 17:24:37 -0700 | [diff] [blame] | 3 | #include "class_linker.h" |
| 4 | #include "dex_file.h" |
| 5 | #include "dex_instruction.h" |
| 6 | #include "dex_instruction_visitor.h" |
Brian Carlstrom | 578bbdc | 2011-07-21 14:07:47 -0700 | [diff] [blame] | 7 | #include "dex_verifier.h" |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 8 | |
Elliott Hughes | 1f359b0 | 2011-07-17 14:27:17 -0700 | [diff] [blame] | 9 | #include <iostream> |
| 10 | |
| 11 | #include "logging.h" |
| 12 | #include "stringpiece.h" |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 13 | |
| 14 | namespace art { |
| 15 | |
jeffhao | ba5ebb9 | 2011-08-25 17:24:37 -0700 | [diff] [blame] | 16 | /* |
| 17 | * Returns "true" if the flags indicate that this address holds the start |
| 18 | * of an instruction. |
| 19 | */ |
| 20 | inline bool InsnIsOpcode(const uint32_t insn_flags[], int addr) { |
| 21 | return (insn_flags[addr] & DexVerify::kInsnFlagWidthMask) != 0; |
| 22 | } |
| 23 | |
| 24 | /* |
| 25 | * Extract the unsigned 16-bit instruction width from "flags". |
| 26 | */ |
| 27 | inline int InsnGetWidth(const uint32_t insn_flags[], int addr) { |
| 28 | return insn_flags[addr] & DexVerify::kInsnFlagWidthMask; |
| 29 | } |
| 30 | |
| 31 | /* |
| 32 | * Changed? |
| 33 | */ |
| 34 | inline bool InsnIsChanged(const uint32_t insn_flags[], int addr) { |
| 35 | return (insn_flags[addr] & DexVerify::kInsnFlagChanged) != 0; |
| 36 | } |
| 37 | inline void InsnSetChanged(uint32_t insn_flags[], int addr, bool changed) { |
| 38 | if (changed) |
| 39 | insn_flags[addr] |= DexVerify::kInsnFlagChanged; |
| 40 | else |
| 41 | insn_flags[addr] &= ~DexVerify::kInsnFlagChanged; |
| 42 | } |
| 43 | |
| 44 | /* |
| 45 | * Visited? |
| 46 | */ |
| 47 | inline bool InsnIsVisited(const uint32_t insn_flags[], int addr) { |
| 48 | return (insn_flags[addr] & DexVerify::kInsnFlagVisited) != 0; |
| 49 | } |
| 50 | inline void InsnSetVisited(uint32_t insn_flags[], int addr, bool changed) { |
| 51 | if (changed) |
| 52 | insn_flags[addr] |= DexVerify::kInsnFlagVisited; |
| 53 | else |
| 54 | insn_flags[addr] &= ~DexVerify::kInsnFlagVisited; |
| 55 | } |
| 56 | |
| 57 | /* |
| 58 | * Visited or changed? |
| 59 | */ |
| 60 | inline bool InsnIsVisitedOrChanged(const uint32_t insn_flags[], int addr) { |
| 61 | return (insn_flags[addr] & (DexVerify::kInsnFlagVisited | |
| 62 | DexVerify::kInsnFlagChanged)) != 0; |
| 63 | } |
| 64 | |
| 65 | /* |
| 66 | * In a "try" block? |
| 67 | */ |
| 68 | inline bool InsnIsInTry(const uint32_t insn_flags[], int addr) { |
| 69 | return (insn_flags[addr] & DexVerify::kInsnFlagInTry) != 0; |
| 70 | } |
| 71 | inline void InsnSetInTry(uint32_t insn_flags[], int addr, bool inTry) { |
| 72 | insn_flags[addr] |= DexVerify::kInsnFlagInTry; |
| 73 | } |
| 74 | |
| 75 | /* |
| 76 | * Instruction is a branch target or exception handler? |
| 77 | */ |
| 78 | inline bool InsnIsBranchTarget(const uint32_t insn_flags[], int addr) { |
| 79 | return (insn_flags[addr] & DexVerify::kInsnFlagBranchTarget) != 0; |
| 80 | } |
| 81 | inline void InsnSetBranchTarget(uint32_t insn_flags[], int addr, bool isBranch) |
| 82 | { |
| 83 | insn_flags[addr] |= DexVerify::kInsnFlagBranchTarget; |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * Instruction is a GC point? |
| 88 | */ |
| 89 | inline bool InsnIsGcPoint(const uint32_t insn_flags[], int addr) { |
| 90 | return (insn_flags[addr] & DexVerify::kInsnFlagGcPoint) != 0; |
| 91 | } |
| 92 | inline void InsnSetGcPoint(uint32_t insn_flags[], int addr, bool isGcPoint) { |
| 93 | insn_flags[addr] |= DexVerify::kInsnFlagGcPoint; |
| 94 | } |
| 95 | |
| 96 | |
| 97 | /* |
| 98 | * Extract the relative offset from a branch instruction. |
| 99 | * |
| 100 | * Returns "false" on failure (e.g. this isn't a branch instruction). |
| 101 | */ |
| 102 | bool GetBranchOffset(const DexFile::CodeItem* code_item, |
| 103 | const uint32_t insn_flags[], int cur_offset, int32_t* pOffset, |
| 104 | bool* pConditional, bool* selfOkay) { |
| 105 | const uint16_t* insns = code_item->insns_ + cur_offset; |
| 106 | |
| 107 | switch (*insns & 0xff) { |
| 108 | case Instruction::GOTO: |
| 109 | *pOffset = ((int16_t) *insns) >> 8; |
| 110 | *pConditional = false; |
| 111 | *selfOkay = false; |
| 112 | break; |
| 113 | case Instruction::GOTO_32: |
| 114 | *pOffset = insns[1] | (((uint32_t) insns[2]) << 16); |
| 115 | *pConditional = false; |
| 116 | *selfOkay = true; |
| 117 | break; |
| 118 | case Instruction::GOTO_16: |
| 119 | *pOffset = (int16_t) insns[1]; |
| 120 | *pConditional = false; |
| 121 | *selfOkay = false; |
| 122 | break; |
| 123 | case Instruction::IF_EQ: |
| 124 | case Instruction::IF_NE: |
| 125 | case Instruction::IF_LT: |
| 126 | case Instruction::IF_GE: |
| 127 | case Instruction::IF_GT: |
| 128 | case Instruction::IF_LE: |
| 129 | case Instruction::IF_EQZ: |
| 130 | case Instruction::IF_NEZ: |
| 131 | case Instruction::IF_LTZ: |
| 132 | case Instruction::IF_GEZ: |
| 133 | case Instruction::IF_GTZ: |
| 134 | case Instruction::IF_LEZ: |
| 135 | *pOffset = (int16_t) insns[1]; |
| 136 | *pConditional = true; |
| 137 | *selfOkay = false; |
| 138 | break; |
| 139 | default: |
| 140 | return false; |
| 141 | break; |
| 142 | } |
| 143 | |
| 144 | return true; |
| 145 | } |
| 146 | |
| 147 | |
| 148 | /* |
| 149 | * Verify an array data table. "cur_offset" is the offset of the |
| 150 | * fill-array-data instruction. |
| 151 | */ |
| 152 | static bool CheckArrayData(const DexFile::CodeItem* code_item, |
| 153 | uint32_t cur_offset) { |
| 154 | const uint32_t insn_count = code_item->insns_size_; |
| 155 | const uint16_t* insns = code_item->insns_ + cur_offset; |
| 156 | const uint16_t* array_data; |
| 157 | int32_t array_data_offset; |
| 158 | |
| 159 | assert(cur_offset < insn_count); |
| 160 | |
| 161 | /* make sure the start of the array data table is in range */ |
| 162 | array_data_offset = insns[1] | (((int32_t) insns[2]) << 16); |
| 163 | if ((int32_t) cur_offset + array_data_offset < 0 || |
| 164 | cur_offset + array_data_offset + 2 >= insn_count) |
| 165 | { |
| 166 | LOG(ERROR) << "VFY: invalid array data start: at " << cur_offset |
| 167 | << ", data offset " << array_data_offset << ", count " |
| 168 | << insn_count; |
| 169 | return false; |
| 170 | } |
| 171 | |
| 172 | /* offset to array data table is a relative branch-style offset */ |
| 173 | array_data = insns + array_data_offset; |
| 174 | |
| 175 | /* make sure the table is 32-bit aligned */ |
| 176 | if ((((uint32_t) array_data) & 0x03) != 0) { |
| 177 | LOG(ERROR) << "VFY: unaligned array data table: at " << cur_offset |
| 178 | << ", data offset " << array_data_offset; |
| 179 | return false; |
| 180 | } |
| 181 | |
| 182 | uint32_t value_width = array_data[1]; |
| 183 | uint32_t value_count = *(uint32_t*) (&array_data[2]); |
| 184 | uint32_t table_size = 4 + (value_width * value_count + 1) / 2; |
| 185 | |
| 186 | /* make sure the end of the switch is in range */ |
| 187 | if (cur_offset + array_data_offset + table_size > insn_count) { |
| 188 | LOG(ERROR) << "VFY: invalid array data end: at " << cur_offset |
| 189 | << ", data offset " << array_data_offset << ", end " |
| 190 | << cur_offset + array_data_offset + table_size << ", count " |
| 191 | << insn_count; |
| 192 | return false; |
| 193 | } |
| 194 | |
| 195 | return true; |
| 196 | } |
| 197 | |
| 198 | /* |
| 199 | * Perform static checks on a "new-instance" instruction. Specifically, |
| 200 | * make sure the class reference isn't for an array class. |
| 201 | * |
| 202 | * We don't need the actual class, just a pointer to the class name. |
| 203 | */ |
| 204 | static bool CheckNewInstance(const DexFile* dex_file, uint32_t idx) { |
| 205 | if (idx >= dex_file->GetHeader().type_ids_size_) { |
| 206 | LOG(ERROR) << "VFY: bad type index " << idx << " (max " |
| 207 | << dex_file->GetHeader().type_ids_size_ << ")"; |
| 208 | return false; |
| 209 | } |
| 210 | |
| 211 | const char* descriptor = dex_file->dexStringByTypeIdx(idx); |
| 212 | if (descriptor[0] != 'L') { |
| 213 | LOG(ERROR) << "VFY: can't call new-instance on type '" |
| 214 | << descriptor << "'"; |
| 215 | return false; |
| 216 | } |
| 217 | |
| 218 | return true; |
| 219 | } |
| 220 | |
| 221 | /* |
| 222 | * Perform static checks on a "new-array" instruction. Specifically, make |
| 223 | * sure they aren't creating an array of arrays that causes the number of |
| 224 | * dimensions to exceed 255. |
| 225 | */ |
| 226 | static bool CheckNewArray(const DexFile* dex_file, uint32_t idx) { |
| 227 | if (idx >= dex_file->GetHeader().type_ids_size_) { |
| 228 | LOG(ERROR) << "VFY: bad type index " << idx << " (max " |
| 229 | << dex_file->GetHeader().type_ids_size_ << ")"; |
| 230 | return false; |
| 231 | } |
| 232 | |
| 233 | int bracket_count = 0; |
| 234 | const char* descriptor = dex_file->dexStringByTypeIdx(idx); |
| 235 | const char* cp = descriptor; |
| 236 | while (*cp++ == '[') |
| 237 | bracket_count++; |
| 238 | |
| 239 | if (bracket_count == 0) { |
| 240 | /* The given class must be an array type. */ |
| 241 | LOG(ERROR) << "VFY: can't new-array class '" << descriptor |
| 242 | << "' (not an array)"; |
| 243 | return false; |
| 244 | } else if (bracket_count > 255) { |
| 245 | /* It is illegal to create an array of more than 255 dimensions. */ |
| 246 | LOG(ERROR) << "VFY: can't new-array class '" << descriptor |
| 247 | << "' (exceeds limit)"; |
| 248 | return false; |
| 249 | } |
| 250 | |
| 251 | return true; |
| 252 | } |
| 253 | |
| 254 | /* |
| 255 | * Perform static checks on an instruction that takes a class constant. |
| 256 | * Ensure that the class index is in the valid range. |
| 257 | */ |
| 258 | static bool CheckTypeIndex(const DexFile* dex_file, uint32_t idx) { |
| 259 | if (idx >= dex_file->GetHeader().type_ids_size_) { |
| 260 | LOG(ERROR) << "VFY: bad type index " << idx << " (max " |
| 261 | << dex_file->GetHeader().type_ids_size_ << ")"; |
| 262 | return false; |
| 263 | } |
| 264 | return true; |
| 265 | } |
| 266 | |
| 267 | /* |
| 268 | * Perform static checks on a field get or set instruction. All we do |
| 269 | * here is ensure that the field index is in the valid range. |
| 270 | */ |
| 271 | static bool CheckFieldIndex(const DexFile* dex_file, uint32_t idx) { |
| 272 | if (idx >= dex_file->GetHeader().field_ids_size_) { |
| 273 | LOG(ERROR) << "VFY: bad field index " << idx << " (max " |
| 274 | << dex_file->GetHeader().field_ids_size_ << ")"; |
| 275 | return false; |
| 276 | } |
| 277 | return true; |
| 278 | } |
| 279 | |
| 280 | /* |
| 281 | * Perform static checks on a method invocation instruction. All we do |
| 282 | * here is ensure that the method index is in the valid range. |
| 283 | */ |
| 284 | static bool CheckMethodIndex(const DexFile* dex_file, uint32_t idx) { |
| 285 | if (idx >= dex_file->GetHeader().method_ids_size_) { |
| 286 | LOG(ERROR) << "VFY: bad method index " << idx << " (max " |
| 287 | << dex_file->GetHeader().method_ids_size_ << ")"; |
| 288 | return false; |
| 289 | } |
| 290 | return true; |
| 291 | } |
| 292 | |
| 293 | /* |
| 294 | * Ensure that the string index is in the valid range. |
| 295 | */ |
| 296 | static bool CheckStringIndex(const DexFile* dex_file, uint32_t idx) { |
| 297 | if (idx >= dex_file->GetHeader().string_ids_size_) { |
| 298 | LOG(ERROR) << "VFY: bad string index " << idx << " (max " |
| 299 | << dex_file->GetHeader().string_ids_size_ << ")"; |
| 300 | return false; |
| 301 | } |
| 302 | return true; |
| 303 | } |
| 304 | |
| 305 | /* |
| 306 | * Ensure that the register index is valid for this code item. |
| 307 | */ |
| 308 | static bool CheckRegisterIndex(const DexFile::CodeItem* code_item, uint32_t idx) |
| 309 | { |
| 310 | if (idx >= code_item->registers_size_) { |
| 311 | LOG(ERROR) << "VFY: register index out of range (" << idx << " >= " |
| 312 | << code_item->registers_size_ << ")"; |
| 313 | return false; |
| 314 | } |
| 315 | return true; |
| 316 | } |
| 317 | |
| 318 | /* |
| 319 | * Ensure that the wide register index is valid for this code item. |
| 320 | */ |
| 321 | static bool CheckWideRegisterIndex(const DexFile::CodeItem* code_item, |
| 322 | uint32_t idx) { |
| 323 | if (idx + 1 >= code_item->registers_size_) { |
| 324 | LOG(ERROR) << "VFY: wide register index out of range (" << idx |
| 325 | << "+1 >= " << code_item->registers_size_ << ")"; |
| 326 | return false; |
| 327 | } |
| 328 | return true; |
| 329 | } |
| 330 | |
| 331 | /* |
| 332 | * Check the register indices used in a "vararg" instruction, such as |
| 333 | * invoke-virtual or filled-new-array. |
| 334 | * |
| 335 | * vA holds word count (0-5), args[] have values. |
| 336 | * |
| 337 | * There are some tests we don't do here, e.g. we don't try to verify |
| 338 | * that invoking a method that takes a double is done with consecutive |
| 339 | * registers. This requires parsing the target method signature, which |
| 340 | * we will be doing later on during the code flow analysis. |
| 341 | */ |
| 342 | static bool CheckVarArgRegs(const DexFile::CodeItem* code_item, uint32_t vA, |
| 343 | uint32_t arg[]) { |
| 344 | uint16_t registers_size = code_item->registers_size_; |
| 345 | uint32_t idx; |
| 346 | |
| 347 | if (vA > 5) { |
| 348 | LOG(ERROR) << "VFY: invalid arg count (" << vA << ") in non-range invoke)"; |
| 349 | return false; |
| 350 | } |
| 351 | |
| 352 | for (idx = 0; idx < vA; idx++) { |
| 353 | if (arg[idx] > registers_size) { |
| 354 | LOG(ERROR) << "VFY: invalid reg index (" << arg[idx] |
| 355 | << ") in non-range invoke (> " << registers_size << ")"; |
| 356 | return false; |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | return true; |
| 361 | } |
| 362 | |
| 363 | /* |
| 364 | * Check the register indices used in a "vararg/range" instruction, such as |
| 365 | * invoke-virtual/range or filled-new-array/range. |
| 366 | * |
| 367 | * vA holds word count, vC holds index of first reg. |
| 368 | */ |
| 369 | static bool CheckVarArgRangeRegs(const DexFile::CodeItem* code_item, |
| 370 | uint32_t vA, uint32_t vC) { |
| 371 | uint16_t registers_size = code_item->registers_size_; |
| 372 | |
| 373 | /* |
| 374 | * vA/vC are unsigned 8-bit/16-bit quantities for /range instructions, |
| 375 | * so there's no risk of integer overflow when adding them here. |
| 376 | */ |
| 377 | if (vA + vC > registers_size) { |
| 378 | LOG(ERROR) << "VFY: invalid reg index " << vA << "+" << vC |
| 379 | << " in range invoke (> " << registers_size << ")"; |
| 380 | return false; |
| 381 | } |
| 382 | |
| 383 | return true; |
| 384 | } |
| 385 | |
| 386 | /* |
| 387 | * Verify a switch table. "cur_offset" is the offset of the switch instruction. |
| 388 | * |
| 389 | * Updates "insnFlags", setting the "branch target" flag. |
| 390 | */ |
| 391 | static bool CheckSwitchTargets(const DexFile::CodeItem* code_item, |
| 392 | uint32_t insn_flags[], uint32_t cur_offset) { |
| 393 | const uint32_t insn_count = code_item->insns_size_; |
| 394 | const uint16_t* insns = code_item->insns_ + cur_offset; |
| 395 | const uint16_t* switch_insns; |
| 396 | uint16_t expected_signature; |
| 397 | uint32_t switch_count, table_size; |
| 398 | int32_t switch_offset, keys_offset, targets_offset; |
| 399 | int32_t offset, abs_offset; |
| 400 | uint32_t targ; |
| 401 | |
| 402 | /* make sure the start of the switch is in range */ |
| 403 | switch_offset = insns[1] | ((int32_t) insns[2]) << 16; |
| 404 | if ((int32_t) cur_offset + switch_offset < 0 || |
| 405 | cur_offset + switch_offset + 2 >= insn_count) { |
| 406 | LOG(ERROR) << "VFY: invalid switch start: at " << cur_offset |
| 407 | << ", switch offset " << switch_offset << ", count " |
| 408 | << insn_count; |
| 409 | return false; |
| 410 | } |
| 411 | |
| 412 | /* offset to switch table is a relative branch-style offset */ |
| 413 | switch_insns = insns + switch_offset; |
| 414 | |
| 415 | /* make sure the table is 32-bit aligned */ |
| 416 | if ((((uint32_t) switch_insns) & 0x03) != 0) { |
| 417 | LOG(ERROR) << "VFY: unaligned switch table: at " << cur_offset |
| 418 | << ", switch offset " << switch_offset; |
| 419 | return false; |
| 420 | } |
| 421 | |
| 422 | switch_count = switch_insns[1]; |
| 423 | |
| 424 | if ((*insns & 0xff) == Instruction::PACKED_SWITCH) { |
| 425 | /* 0=sig, 1=count, 2/3=firstKey */ |
| 426 | targets_offset = 4; |
| 427 | keys_offset = -1; |
| 428 | expected_signature = Instruction::kPackedSwitchSignature; |
| 429 | } else { |
| 430 | /* 0=sig, 1=count, 2..count*2 = keys */ |
| 431 | keys_offset = 2; |
| 432 | targets_offset = 2 + 2 * switch_count; |
| 433 | expected_signature = Instruction::kSparseSwitchSignature; |
| 434 | } |
| 435 | table_size = targets_offset + switch_count * 2; |
| 436 | |
| 437 | if (switch_insns[0] != expected_signature) { |
| 438 | LOG(ERROR) << "VFY: wrong signature for switch table (0x" << switch_insns[0] |
| 439 | << ", wanted 0x" << expected_signature << ")"; |
| 440 | return false; |
| 441 | } |
| 442 | |
| 443 | /* make sure the end of the switch is in range */ |
| 444 | if (cur_offset + switch_offset + table_size > (uint32_t) insn_count) { |
| 445 | LOG(ERROR) << "VFY: invalid switch end: at " << cur_offset |
| 446 | << ", switch offset " << switch_offset << ", end " |
| 447 | << cur_offset + switch_offset + table_size << ", count " |
| 448 | << insn_count; |
| 449 | return false; |
| 450 | } |
| 451 | |
| 452 | /* for a sparse switch, verify the keys are in ascending order */ |
| 453 | if (keys_offset > 0 && switch_count > 1) { |
| 454 | int32_t last_key; |
| 455 | |
| 456 | last_key = switch_insns[keys_offset] | |
| 457 | (switch_insns[keys_offset + 1] << 16); |
| 458 | for (targ = 1; targ < switch_count; targ++) { |
| 459 | int32_t key = (int32_t) switch_insns[keys_offset + targ * 2] | |
| 460 | (int32_t) (switch_insns[keys_offset + targ * 2 + 1] << 16); |
| 461 | if (key <= last_key) { |
| 462 | LOG(ERROR) << "VFY: invalid packed switch: last key=" << last_key |
| 463 | << ", this=" << key; |
| 464 | return false; |
| 465 | } |
| 466 | |
| 467 | last_key = key; |
| 468 | } |
| 469 | } |
| 470 | |
| 471 | /* verify each switch target */ |
| 472 | for (targ = 0; targ < switch_count; targ++) { |
| 473 | offset = (int32_t) switch_insns[targets_offset + targ * 2] | |
| 474 | (int32_t) (switch_insns[targets_offset + targ * 2 + 1] << 16); |
| 475 | abs_offset = cur_offset + offset; |
| 476 | |
| 477 | if (abs_offset < 0 || abs_offset >= (int32_t) insn_count || |
| 478 | !InsnIsOpcode(insn_flags, abs_offset)) { |
| 479 | LOG(ERROR) << "VFY: invalid switch target " << offset << " (-> " |
| 480 | << abs_offset << ") at " << cur_offset << "[" << targ << "]"; |
| 481 | return false; |
| 482 | } |
| 483 | InsnSetBranchTarget(insn_flags, abs_offset, true); |
| 484 | } |
| 485 | |
| 486 | return true; |
| 487 | } |
| 488 | |
| 489 | /* |
| 490 | * Verify that the target of a branch instruction is valid. |
| 491 | * |
| 492 | * We don't expect code to jump directly into an exception handler, but |
| 493 | * it's valid to do so as long as the target isn't a "move-exception" |
| 494 | * instruction. We verify that in a later stage. |
| 495 | * |
| 496 | * The VM spec doesn't forbid an instruction from branching to itself, |
| 497 | * but the Dalvik spec declares that only certain instructions can do so. |
| 498 | * |
| 499 | * Updates "insnFlags", setting the "branch target" flag. |
| 500 | */ |
| 501 | static bool CheckBranchTarget(const DexFile::CodeItem* code_item, |
| 502 | uint32_t insn_flags[], int cur_offset) { |
| 503 | const int insn_count = code_item->insns_size_; |
| 504 | int32_t offset, abs_offset; |
| 505 | bool isConditional, selfOkay; |
| 506 | |
| 507 | if (!GetBranchOffset(code_item, insn_flags, cur_offset, &offset, |
| 508 | &isConditional, &selfOkay)) |
| 509 | return false; |
| 510 | |
| 511 | if (!selfOkay && offset == 0) { |
| 512 | LOG(ERROR) << "VFY: branch offset of zero not allowed at" << cur_offset; |
| 513 | return false; |
| 514 | } |
| 515 | |
| 516 | /* |
| 517 | * Check for 32-bit overflow. This isn't strictly necessary if we can |
| 518 | * depend on the VM to have identical "wrap-around" behavior, but |
| 519 | * it's unwise to depend on that. |
| 520 | */ |
| 521 | if (((int64_t) cur_offset + (int64_t) offset) != |
| 522 | (int64_t)(cur_offset + offset)) { |
| 523 | LOG(ERROR) << "VFY: branch target overflow " << cur_offset << " +" |
| 524 | << offset; |
| 525 | return false; |
| 526 | } |
| 527 | abs_offset = cur_offset + offset; |
| 528 | if (abs_offset < 0 || abs_offset >= insn_count || |
| 529 | !InsnIsOpcode(insn_flags, abs_offset)) |
| 530 | { |
| 531 | LOG(ERROR) << "VFY: invalid branch target " << offset << " (-> " |
| 532 | << abs_offset << ") at " << cur_offset; |
| 533 | return false; |
| 534 | } |
| 535 | InsnSetBranchTarget(insn_flags, abs_offset, true); |
| 536 | |
| 537 | return true; |
| 538 | } |
| 539 | |
| 540 | bool CheckInsnWidth(const uint16_t* insns, uint32_t insns_size, |
| 541 | uint32_t insn_flags[]) { |
| 542 | const byte* ptr = reinterpret_cast<const byte*>(insns); |
| 543 | const Instruction* inst = Instruction::At(ptr); |
| 544 | |
| 545 | size_t width = 0; |
| 546 | |
| 547 | while (width < insns_size) { |
| 548 | insn_flags[width] |= inst->Size(); |
| 549 | width += inst->Size(); |
| 550 | inst = inst->Next(); |
| 551 | } |
| 552 | |
| 553 | if (width != insns_size) { |
| 554 | LOG(ERROR) << "VFY: code did not end where expected (" << width << " vs. " |
| 555 | << insns_size << ")"; |
| 556 | return false; |
| 557 | } |
| 558 | |
| 559 | return true; |
| 560 | } |
| 561 | |
| 562 | /* |
| 563 | * Set the "in try" flags for all instructions protected by "try" statements. |
| 564 | * Also sets the "branch target" flags for exception handlers. |
| 565 | * |
| 566 | * Call this after widths have been set in "insn_flags". |
| 567 | * |
| 568 | * Returns "false" if something in the exception table looks fishy, but |
| 569 | * we're expecting the exception table to be somewhat sane. |
| 570 | */ |
| 571 | static bool ScanTryCatchBlocks(const DexFile::CodeItem* code_item, |
| 572 | uint32_t insn_flags[]) { |
| 573 | uint32_t insns_size = code_item->insns_size_; |
| 574 | uint32_t tries_size = code_item->tries_size_; |
| 575 | |
| 576 | if (tries_size == 0) { |
| 577 | return true; |
| 578 | } |
| 579 | |
| 580 | const DexFile::TryItem* tries = DexFile::dexGetTryItems(*code_item, 0); |
| 581 | |
| 582 | for (uint32_t idx = 0; idx < tries_size; idx++) { |
| 583 | const DexFile::TryItem* try_item = &tries[idx]; |
| 584 | uint32_t start = try_item->start_addr_; |
| 585 | uint32_t end = start + try_item->insn_count_; |
| 586 | |
| 587 | if ((start >= end) || (start >= insns_size) || (end > insns_size)) { |
| 588 | LOG(ERROR) << "VFY: bad exception entry: startAddr=" << start |
| 589 | << " endAddr=" << end << " (size=" << insns_size << ")"; |
| 590 | return false; |
| 591 | } |
| 592 | |
| 593 | if (InsnGetWidth(insn_flags, start) == 0) { |
| 594 | LOG(ERROR) << "VFY: 'try' block starts inside an instruction (" |
| 595 | << start << ")"; |
| 596 | return false; |
| 597 | } |
| 598 | |
| 599 | uint32_t addr; |
| 600 | for (addr = start; addr < end; addr += InsnGetWidth(insn_flags, addr)) { |
| 601 | InsnSetInTry(insn_flags, addr, true); |
| 602 | } |
| 603 | } |
| 604 | |
| 605 | /* Iterate over each of the handlers to verify target addresses. */ |
| 606 | const byte* handlers_ptr = DexFile::dexGetCatchHandlerData(*code_item, 0); |
| 607 | uint32_t handlers_size = DecodeUnsignedLeb128(&handlers_ptr); |
| 608 | for (uint32_t idx = 0; idx < handlers_size; idx++) { |
| 609 | DexFile::CatchHandlerIterator iterator(handlers_ptr); |
| 610 | |
| 611 | for (; !iterator.HasNext(); iterator.Next()) { |
| 612 | uint32_t addr = iterator.Get().address_; |
| 613 | if (InsnGetWidth(insn_flags, addr) == 0) { |
| 614 | LOG(ERROR) << "VFY: exception handler starts at bad address (" |
| 615 | << addr << ")"; |
| 616 | return false; |
| 617 | } |
| 618 | |
| 619 | InsnSetBranchTarget(insn_flags, addr, true); |
| 620 | } |
| 621 | |
| 622 | handlers_ptr = iterator.GetData(); |
| 623 | } |
| 624 | |
| 625 | return true; |
| 626 | } |
| 627 | |
| 628 | |
| 629 | |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 630 | bool DexVerify::VerifyClass(Class* klass) { |
| 631 | if (klass->IsVerified()) { |
| 632 | return true; |
| 633 | } |
| 634 | for (size_t i = 0; i < klass->NumDirectMethods(); ++i) { |
| 635 | Method* method = klass->GetDirectMethod(i); |
| 636 | if (!VerifyMethod(method)) { |
jeffhao | ba5ebb9 | 2011-08-25 17:24:37 -0700 | [diff] [blame] | 637 | LOG(ERROR) << "Verifier rejected class " |
| 638 | << klass->GetDescriptor()->ToModifiedUtf8(); |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 639 | return false; |
| 640 | } |
| 641 | } |
| 642 | for (size_t i = 0; i < klass->NumVirtualMethods(); ++i) { |
| 643 | Method* method = klass->GetVirtualMethod(i); |
| 644 | if (!VerifyMethod(method)) { |
jeffhao | ba5ebb9 | 2011-08-25 17:24:37 -0700 | [diff] [blame] | 645 | LOG(ERROR) << "Verifier rejected class " |
| 646 | << klass->GetDescriptor()->ToModifiedUtf8(); |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 647 | return false; |
| 648 | } |
| 649 | } |
| 650 | return true; |
| 651 | } |
| 652 | |
| 653 | bool DexVerify::VerifyMethod(Method* method) { |
jeffhao | ba5ebb9 | 2011-08-25 17:24:37 -0700 | [diff] [blame] | 654 | const DexCache* dex_cache = method->GetDeclaringClass()->GetDexCache(); |
| 655 | ClassLinker* class_linker = Runtime::Current()->GetClassLinker(); |
| 656 | const DexFile& dex_file = class_linker->FindDexFile(dex_cache); |
| 657 | const DexFile::CodeItem *code_item = dex_file.GetCodeItem(method->code_off_); |
| 658 | |
| 659 | /* |
| 660 | * If there aren't any instructions, make sure that's expected, then |
| 661 | * exit successfully. |
| 662 | */ |
| 663 | if (code_item == NULL) { |
| 664 | if (!method->IsNative() && !method->IsAbstract()) { |
| 665 | LOG(ERROR) << "VFY: zero-length code in concrete non-native method"; |
| 666 | return false; |
| 667 | } |
| 668 | return true; |
| 669 | } |
| 670 | |
| 671 | /* |
| 672 | * Sanity-check the register counts. ins + locals = registers, so make |
| 673 | * sure that ins <= registers. |
| 674 | */ |
| 675 | if (code_item->ins_size_ > code_item->registers_size_) { |
| 676 | LOG(ERROR) << "VFY: bad register counts (ins=" << code_item->ins_size_ |
| 677 | << " regs=" << code_item->registers_size_; |
| 678 | return false; |
| 679 | } |
| 680 | |
| 681 | /* |
| 682 | * Allocate and initialize an array to hold instruction data. |
| 683 | */ |
| 684 | uint32_t* insn_flags = new uint32_t[code_item->insns_size_](); |
| 685 | |
| 686 | /* |
| 687 | * Run through the instructions and see if the width checks out. |
| 688 | */ |
| 689 | if (!CheckInsnWidth(code_item->insns_, code_item->insns_size_, insn_flags)) { |
| 690 | delete insn_flags; |
| 691 | return false; |
| 692 | } |
| 693 | |
| 694 | /* |
| 695 | * Flag instructions guarded by a "try" block and check exception handlers. |
| 696 | */ |
| 697 | if (!ScanTryCatchBlocks(code_item, insn_flags)) { |
| 698 | delete insn_flags; |
| 699 | return false; |
| 700 | } |
| 701 | |
| 702 | /* |
| 703 | * Perform static instruction verification. |
| 704 | */ |
| 705 | if (!VerifyInstructions(&dex_file, code_item, insn_flags)) { |
| 706 | delete insn_flags; |
| 707 | return false; |
| 708 | } |
| 709 | |
| 710 | /* |
| 711 | * TODO: Code flow analysis |
| 712 | */ |
| 713 | |
| 714 | delete insn_flags; |
| 715 | return true; |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 716 | } |
| 717 | |
jeffhao | ba5ebb9 | 2011-08-25 17:24:37 -0700 | [diff] [blame] | 718 | bool DexVerify::VerifyInstructions(const DexFile* dex_file, |
| 719 | const DexFile::CodeItem* code_item, uint32_t insn_flags[]) { |
| 720 | const byte* ptr = reinterpret_cast<const byte*>(code_item->insns_); |
| 721 | const Instruction* inst = Instruction::At(ptr); |
| 722 | |
| 723 | /* Flag the start of the method as a branch target. */ |
| 724 | InsnSetBranchTarget(insn_flags, 0, true); |
| 725 | |
| 726 | uint32_t width = 0; |
| 727 | uint32_t insns_size = code_item->insns_size_; |
| 728 | |
| 729 | while (width < insns_size) { |
| 730 | if (!VerifyInstruction(dex_file, inst, width, code_item, insn_flags)) { |
| 731 | LOG(ERROR) << "VFY: rejecting opcode 0x" << std::hex |
| 732 | << (int) inst->Opcode() << " at 0x" << width << std::dec; |
| 733 | return false; |
| 734 | } |
| 735 | |
| 736 | /* Flag instructions that are garbage collection points */ |
| 737 | if (inst->IsBranch() || inst->IsSwitch() || inst->IsThrow() || |
| 738 | inst->IsReturn()) { |
| 739 | InsnSetGcPoint(insn_flags, width, true); |
| 740 | } |
| 741 | |
| 742 | width += inst->Size(); |
| 743 | inst = inst->Next(); |
| 744 | } |
| 745 | return true; |
| 746 | } |
| 747 | |
| 748 | bool DexVerify::VerifyInstruction(const DexFile* dex_file, |
| 749 | const Instruction* inst, uint32_t code_offset, |
| 750 | const DexFile::CodeItem* code_item, uint32_t insn_flags[]) { |
| 751 | Instruction::Code opcode = inst->Opcode(); |
| 752 | bool result = true; |
| 753 | uint32_t vA, vB, vC; |
| 754 | uint64_t vB_wide; |
| 755 | uint32_t arg[5]; |
| 756 | |
| 757 | inst->Decode(vA, vB, vB_wide, vC, arg); |
| 758 | |
| 759 | int argumentA = inst->GetVerifyTypeArgumentA(); |
| 760 | int argumentB = inst->GetVerifyTypeArgumentB(); |
| 761 | int argumentC = inst->GetVerifyTypeArgumentC(); |
| 762 | int extra_flags = inst->GetVerifyExtraFlags(); |
| 763 | |
| 764 | switch (argumentA) { |
| 765 | case Instruction::kVerifyRegA: |
| 766 | result &= CheckRegisterIndex(code_item, vA); |
| 767 | break; |
| 768 | case Instruction::kVerifyRegAWide: |
| 769 | result &= CheckWideRegisterIndex(code_item, vA); |
| 770 | break; |
| 771 | } |
| 772 | |
| 773 | switch (argumentB) { |
| 774 | case Instruction::kVerifyRegB: |
| 775 | result &= CheckRegisterIndex(code_item, vB); |
| 776 | break; |
| 777 | case Instruction::kVerifyRegBField: |
| 778 | result &= CheckFieldIndex(dex_file, vB); |
| 779 | break; |
| 780 | case Instruction::kVerifyRegBMethod: |
| 781 | result &= CheckMethodIndex(dex_file, vB); |
| 782 | break; |
| 783 | case Instruction::kVerifyRegBNewInstance: |
| 784 | result &= CheckNewInstance(dex_file, vB); |
| 785 | break; |
| 786 | case Instruction::kVerifyRegBString: |
| 787 | result &= CheckStringIndex(dex_file, vB); |
| 788 | break; |
| 789 | case Instruction::kVerifyRegBType: |
| 790 | result &= CheckTypeIndex(dex_file, vB); |
| 791 | break; |
| 792 | case Instruction::kVerifyRegBWide: |
| 793 | result &= CheckWideRegisterIndex(code_item, vB); |
| 794 | break; |
| 795 | } |
| 796 | |
| 797 | switch (argumentC) { |
| 798 | case Instruction::kVerifyRegC: |
| 799 | result &= CheckRegisterIndex(code_item, vC); |
| 800 | break; |
| 801 | case Instruction::kVerifyRegCField: |
| 802 | result &= CheckFieldIndex(dex_file, vC); |
| 803 | break; |
| 804 | case Instruction::kVerifyRegCNewArray: |
| 805 | result &= CheckNewArray(dex_file, vC); |
| 806 | break; |
| 807 | case Instruction::kVerifyRegCType: |
| 808 | result &= CheckTypeIndex(dex_file, vC); |
| 809 | break; |
| 810 | case Instruction::kVerifyRegCWide: |
| 811 | result &= CheckWideRegisterIndex(code_item, vC); |
| 812 | break; |
| 813 | } |
| 814 | |
| 815 | switch (extra_flags) { |
| 816 | case Instruction::kVerifyArrayData: |
| 817 | result &= CheckArrayData(code_item, code_offset); |
| 818 | break; |
| 819 | case Instruction::kVerifyBranchTarget: |
| 820 | result &= CheckBranchTarget(code_item, insn_flags, code_offset); |
| 821 | break; |
| 822 | case Instruction::kVerifySwitchTargets: |
| 823 | result &= CheckSwitchTargets(code_item, insn_flags, code_offset); |
| 824 | break; |
| 825 | case Instruction::kVerifyVarArg: |
| 826 | result &= CheckVarArgRegs(code_item, vA, arg); |
| 827 | break; |
| 828 | case Instruction::kVerifyVarArgRange: |
| 829 | result &= CheckVarArgRangeRegs(code_item, vA, vC); |
| 830 | break; |
| 831 | case Instruction::kVerifyError: |
| 832 | LOG(ERROR) << "VFY: unexpected opcode " << (int) opcode; |
| 833 | result = false; |
| 834 | break; |
| 835 | } |
| 836 | |
| 837 | return result; |
| 838 | }; |
| 839 | |
Carl Shapiro | 0e5d75d | 2011-07-06 18:28:37 -0700 | [diff] [blame] | 840 | } // namespace art |