+
+ // First look for compressed info and use it if it exists.
+ const struct macho_segment_command* linkEditSeg = NULL;
+ const dyld_info_command* dyldInfoCmd = NULL;
+ for (uint32_t i = 0; i < cmd_count; ++i) {
+ switch (cmd->cmd) {
+ case LC_SEGMENT_COMMAND:
+ {
+ const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
+ if ( strcmp(seg->segname, "__LINKEDIT") == 0 )
+ linkEditSeg = seg;
+ break;
+ }
+ case LC_DYLD_INFO_ONLY:
+ dyldInfoCmd = (struct dyld_info_command*)cmd;
+ break;
+ }
+ if (dyldInfoCmd && linkEditSeg)
+ break;
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+ if ( linkEditSeg == NULL )
+ throw "dyld missing LINKEDIT";
+
+ // Reset the iterator.
+ cmd = cmds;
+
+ auto getSegmentAtIndex = [cmd_count, cmds](unsigned segIndex) -> const struct macho_segment_command* {
+ const struct load_command* cmd = cmds;
+ for (uint32_t i = 0; i < cmd_count; ++i) {
+ switch (cmd->cmd) {
+ case LC_SEGMENT_COMMAND:
+ if (!segIndex) {
+ const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
+ return seg;
+ }
+ --segIndex;
+ break;
+ }
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+ throw "out of bounds command";
+ return 0;
+ };
+
+ auto segActualLoadAddress = [&](unsigned segIndex) -> uintptr_t {
+ const struct macho_segment_command* seg = getSegmentAtIndex(segIndex);
+ return seg->vmaddr + slide;
+ };
+
+#if __has_feature(ptrauth_calls)
+ auto imageBaseAddress = [cmds, cmd_count]() -> uintptr_t {
+ const struct load_command* cmd = cmds;
+ for (uint32_t i = 0; i < cmd_count; ++i) {
+ switch (cmd->cmd) {
+ case LC_SEGMENT_COMMAND: {
+ const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
+ if ( (seg->fileoff == 0) && (seg->filesize != 0) )
+ return seg->vmaddr;
+ break;
+ }
+ }
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+ return 0;
+ };
+#endif
+
+ if (dyldInfoCmd && (dyldInfoCmd->bind_size != 0) ) {
+ if ( dyldInfoCmd->rebase_size != 0 )
+ throw "unthreaded rebases are not supported";
+
+ const uint8_t* linkEditBase = (uint8_t*)(linkEditSeg->vmaddr + slide - linkEditSeg->fileoff);
+
+ const uint8_t* const start = linkEditBase + dyldInfoCmd->bind_off;
+ const uint8_t* const end = &start[dyldInfoCmd->bind_size];
+ const uint8_t* p = start;
+
+ uintptr_t segmentStartAddress = 0;
+ uint64_t segOffset = 0;
+ int segIndex = 0;
+#if __has_feature(ptrauth_calls)
+ uintptr_t fBaseAddress = imageBaseAddress();
+#endif
+ bool done = false;
+
+ while ( !done && (p < end) ) {
+ uint8_t immediate = *p & BIND_IMMEDIATE_MASK;
+ uint8_t opcode = *p & BIND_OPCODE_MASK;
+ ++p;
+ switch (opcode) {
+ case BIND_OPCODE_DONE:
+ done = true;
+ break;
+ case BIND_OPCODE_SET_DYLIB_ORDINAL_IMM:
+ break;
+ case BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
+ break;
+ case BIND_OPCODE_SET_DYLIB_SPECIAL_IMM:
+ break;
+ case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
+ while (*p != '\0')
+ ++p;
+ ++p;
+ break;
+ case BIND_OPCODE_SET_TYPE_IMM:
+ break;
+ case BIND_OPCODE_SET_ADDEND_SLEB:
+ read_sleb128(p, end);
+ break;
+ case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
+ segIndex = immediate;
+ segmentStartAddress = segActualLoadAddress(segIndex);
+ segOffset = read_uleb128(p, end);
+ break;
+ case BIND_OPCODE_ADD_ADDR_ULEB:
+ segOffset += read_uleb128(p, end);
+ break;
+ case BIND_OPCODE_DO_BIND:
+ break;
+ case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
+ break;
+ case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
+ break;
+ case BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB:
+ read_uleb128(p, end);
+ read_uleb128(p, end);
+ break;
+ case BIND_OPCODE_THREADED:
+ // Note the immediate is a sub opcode
+ switch (immediate) {
+ case BIND_SUBOPCODE_THREADED_SET_BIND_ORDINAL_TABLE_SIZE_ULEB:
+ read_uleb128(p, end);
+ break;
+ case BIND_SUBOPCODE_THREADED_APPLY: {
+ uint64_t delta = 0;
+ do {
+ uintptr_t address = segmentStartAddress + (uintptr_t)segOffset;
+ uint64_t value = *(uint64_t*)address;
+
+#if __has_feature(ptrauth_calls)
+ uint16_t diversity = (uint16_t)(value >> 32);
+ bool hasAddressDiversity = (value & (1ULL << 48)) != 0;
+ ptrauth_key key = (ptrauth_key)((value >> 49) & 0x3);
+ bool isAuthenticated = (value & (1ULL << 63)) != 0;
+#endif
+ bool isRebase = (value & (1ULL << 62)) == 0;
+ if (isRebase) {
+
+#if __has_feature(ptrauth_calls)
+ if (isAuthenticated) {
+ // The new value for a rebase is the low 32-bits of the threaded value plus the slide.
+ uint64_t newValue = (value & 0xFFFFFFFF) + slide;
+ // Add in the offset from the mach_header
+ newValue += fBaseAddress;
+ // We have bits to merge in to the discriminator
+ uintptr_t discriminator = diversity;
+ if (hasAddressDiversity) {
+ // First calculate a new discriminator using the address of where we are trying to store the value
+ discriminator = __builtin_ptrauth_blend_discriminator((void*)address, discriminator);
+ }
+ switch (key) {
+ case ptrauth_key_asia:
+ newValue = (uintptr_t)__builtin_ptrauth_sign_unauthenticated((void*)newValue, ptrauth_key_asia, discriminator);
+ break;
+ case ptrauth_key_asib:
+ newValue = (uintptr_t)__builtin_ptrauth_sign_unauthenticated((void*)newValue, ptrauth_key_asib, discriminator);
+ break;
+ case ptrauth_key_asda:
+ newValue = (uintptr_t)__builtin_ptrauth_sign_unauthenticated((void*)newValue, ptrauth_key_asda, discriminator);
+ break;
+ case ptrauth_key_asdb:
+ newValue = (uintptr_t)__builtin_ptrauth_sign_unauthenticated((void*)newValue, ptrauth_key_asdb, discriminator);
+ break;
+ }
+ *(uint64_t*)address = newValue;
+ } else
+#endif
+ {
+ // Regular pointer which needs to fit in 51-bits of value.
+ // C++ RTTI uses the top bit, so we'll allow the whole top-byte
+ // and the signed-extended bottom 43-bits to be fit in to 51-bits.
+ uint64_t top8Bits = value & 0x0007F80000000000ULL;
+ uint64_t bottom43Bits = value & 0x000007FFFFFFFFFFULL;
+ uint64_t targetValue = ( top8Bits << 13 ) | (((intptr_t)(bottom43Bits << 21) >> 21) & 0x00FFFFFFFFFFFFFF);
+ targetValue = targetValue + slide;
+ *(uint64_t*)address = targetValue;
+ }
+ }
+
+ // The delta is bits [51..61]
+ // And bit 62 is to tell us if we are a rebase (0) or bind (1)
+ value &= ~(1ULL << 62);
+ delta = ( value & 0x3FF8000000000000 ) >> 51;
+ segOffset += delta * sizeof(uintptr_t);
+ } while ( delta != 0 );
+ break;
+ }
+ default:
+ throw "unknown threaded bind subopcode";
+ }
+ break;
+ default:
+ throw "unknown bind opcode";
+ }
+ }
+ return;
+ }
+
projects / apple / dyld.git / blobdiff