]> git.saurik.com Git - apple/dyld.git/blobdiff - src/ImageLoaderMachO.cpp
dyld-360.19.tar.gz
[apple/dyld.git] / src / ImageLoaderMachO.cpp
index b068b7a03779efb0bfba4f7c656c5076d002f071..d552ef3bf06015f055843ad5cdb984fe0ce5e925 100644 (file)
 #include <mach-o/loader.h> 
 #include <mach-o/nlist.h> 
 #include <sys/sysctl.h>
+#include <sys/syscall.h>
 #include <libkern/OSAtomic.h>
 #include <libkern/OSCacheControl.h>
 #include <stdint.h>
+#include <System/sys/codesign.h>
 
 #include "ImageLoaderMachO.h"
 #include "ImageLoaderMachOCompressed.h"
+#if SUPPORT_CLASSIC_MACHO
 #include "ImageLoaderMachOClassic.h"
+#endif
 #include "mach-o/dyld_images.h"
 
 // <rdar://problem/8718137> use stack guard random value to add padding between dylibs
@@ -56,16 +60,27 @@ extern "C" long __stack_chk_guard;
        #define LC_LOAD_UPWARD_DYLIB (0x23|LC_REQ_DYLD) /* load of dylib whose initializers run later */
 #endif
 
+#ifndef LC_VERSION_MIN_TVOS
+       #define LC_VERSION_MIN_TVOS 0x2F
+#endif
+
+#ifndef LC_VERSION_MIN_WATCHOS
+       #define LC_VERSION_MIN_WATCHOS 0x30
+#endif
+
+
 // relocation_info.r_length field has value 3 for 64-bit executables and value 2 for 32-bit executables
 #if __LP64__
        #define LC_SEGMENT_COMMAND              LC_SEGMENT_64
        #define LC_ROUTINES_COMMAND             LC_ROUTINES_64
+       #define LC_SEGMENT_COMMAND_WRONG LC_SEGMENT
        struct macho_segment_command    : public segment_command_64  {};
        struct macho_section                    : public section_64  {};        
        struct macho_routines_command   : public routines_command_64  {};       
 #else
        #define LC_SEGMENT_COMMAND              LC_SEGMENT
        #define LC_ROUTINES_COMMAND             LC_ROUTINES
+       #define LC_SEGMENT_COMMAND_WRONG LC_SEGMENT_64
        struct macho_segment_command    : public segment_command {};
        struct macho_section                    : public section  {};   
        struct macho_routines_command   : public routines_command  {};  
@@ -77,9 +92,9 @@ uint32_t ImageLoaderMachO::fgSymbolTrieSearchs = 0;
 
 ImageLoaderMachO::ImageLoaderMachO(const macho_header* mh, const char* path, unsigned int segCount, 
                                                                                                                                uint32_t segOffsets[], unsigned int libCount)
- : ImageLoader(path, libCount), fMachOData((uint8_t*)mh), fLinkEditBase(NULL), fSlide(0), 
+ : ImageLoader(path, libCount), fCoveredCodeLength(0), fMachOData((uint8_t*)mh), fLinkEditBase(NULL), fSlide(0),
        fEHFrameSectionOffset(0), fUnwindInfoSectionOffset(0), fDylibIDOffset(0), 
-       fSegmentsCount(segCount), fIsSplitSeg(false), fInSharedCache(false),  
+fSegmentsCount(segCount), fIsSplitSeg(false), fInSharedCache(false),
 #if TEXT_RELOC_SUPPORT
        fTextSegmentRebases(false),
        fTextSegmentBinds(false),
@@ -88,7 +103,7 @@ ImageLoaderMachO::ImageLoaderMachO(const macho_header* mh, const char* path, uns
        fReadOnlyImportSegment(false),
 #endif
        fHasSubLibraries(false), fHasSubUmbrella(false), fInUmbrella(false), fHasDOFSections(false), fHasDashInit(false),
-       fHasInitializers(false), fHasTerminators(false), fGoodFirstSegment(false), fRegisteredAsRequiresCoalescing(false)
+       fHasInitializers(false), fHasTerminators(false), fRegisteredAsRequiresCoalescing(false)
 {
        fIsSplitSeg = ((mh->flags & MH_SPLIT_SEGS) != 0);        
 
@@ -103,7 +118,7 @@ ImageLoaderMachO::ImageLoaderMachO(const macho_header* mh, const char* path, uns
                        // ignore zero-sized segments
                        if ( segCmd->vmsize != 0 ) {
                                // record offset of load command
-                               segOffsets[segIndex++] = (uint8_t*)segCmd - fMachOData;
+                               segOffsets[segIndex++] = (uint32_t)((uint8_t*)segCmd - fMachOData);
                        }
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
@@ -113,28 +128,95 @@ ImageLoaderMachO::ImageLoaderMachO(const macho_header* mh, const char* path, uns
 
 
 // determine if this mach-o file has classic or compressed LINKEDIT and number of segments it has
-void ImageLoaderMachO::sniffLoadCommands(const macho_header* mh, const char* path, bool* compressed, 
-                                                                                       unsigned int* segCount, unsigned int* libCount,
-                                                                                       const linkedit_data_command** codeSigCmd)
+void ImageLoaderMachO::sniffLoadCommands(const macho_header* mh, const char* path, bool inCache, bool* compressed,
+                                                                                       unsigned int* segCount, unsigned int* libCount, const LinkContext& context,
+                                                                                       const linkedit_data_command** codeSigCmd,
+                                                                                       const encryption_info_command** encryptCmd)
 {
        *compressed = false;
        *segCount = 0;
        *libCount = 0;
        *codeSigCmd = NULL;
+       *encryptCmd = NULL;
+
        const uint32_t cmd_count = mh->ncmds;
-       const struct load_command* const cmds    = (struct load_command*)(((uint8_t*)mh) + sizeof(macho_header));
+       const struct load_command* const startCmds    = (struct load_command*)(((uint8_t*)mh) + sizeof(macho_header));
        const struct load_command* const endCmds = (struct load_command*)(((uint8_t*)mh) + sizeof(macho_header) + mh->sizeofcmds);
-       const struct load_command* cmd = cmds;
+       const struct load_command* cmd = startCmds;
+       bool foundLoadCommandSegment = false;
        for (uint32_t i = 0; i < cmd_count; ++i) {
+               uint32_t cmdLength = cmd->cmdsize;
+               struct macho_segment_command* segCmd;
+               if ( cmdLength < 8 ) {
+                       dyld::throwf("malformed mach-o image: load command #%d length (%u) too small in %s",
+                                                                                          i, cmdLength, path);
+               }
+               const struct load_command* const nextCmd = (const struct load_command*)(((char*)cmd)+cmdLength);
+               if ( (nextCmd > endCmds) || (nextCmd < cmd) ) {
+                       dyld::throwf("malformed mach-o image: load command #%d length (%u) would exceed sizeofcmds (%u) in %s",
+                                                                                          i, cmdLength, mh->sizeofcmds, path);
+               }
                switch (cmd->cmd) {
                        case LC_DYLD_INFO:
                        case LC_DYLD_INFO_ONLY:
                                *compressed = true;
                                break;
                        case LC_SEGMENT_COMMAND:
+                               segCmd = (struct macho_segment_command*)cmd;
+#if __MAC_OS_X_VERSION_MIN_REQUIRED
+                               // rdar://problem/19617624 allow unmapped segments on OSX (but not iOS)
+                               if ( (segCmd->filesize > segCmd->vmsize) && (segCmd->vmsize != 0) )
+#else
+                               if ( segCmd->filesize > segCmd->vmsize )
+#endif
+                                   dyld::throwf("malformed mach-o image: segment load command %s filesize is larger than vmsize", segCmd->segname);
                                // ignore zero-sized segments
-                               if ( ((struct macho_segment_command*)cmd)->vmsize != 0 )
+                               if ( segCmd->vmsize != 0 )
                                        *segCount += 1;
+                               if ( context.codeSigningEnforced ) {
+                                       uintptr_t vmStart   = segCmd->vmaddr;
+                                       uintptr_t vmSize    = segCmd->vmsize;
+                                       uintptr_t vmEnd     = vmStart + vmSize;
+                                       uintptr_t fileStart = segCmd->fileoff;
+                                       uintptr_t fileSize  = segCmd->filesize;
+                                       if ( (intptr_t)(vmEnd) < 0)
+                                               dyld::throwf("malformed mach-o image: segment load command %s vmsize too large", segCmd->segname);
+                                       if ( vmStart > vmEnd )
+                                               dyld::throwf("malformed mach-o image: segment load command %s wraps around address space", segCmd->segname);
+                                       if ( vmSize != fileSize ) {
+                                               if ( (segCmd->initprot == 0) && (fileSize != 0) )
+                                                       dyld::throwf("malformed mach-o image: unaccessable segment %s has filesize != 0", segCmd->segname);
+                                               else if ( vmSize < fileSize )
+                                                       dyld::throwf("malformed mach-o image: segment %s has vmsize < filesize", segCmd->segname);
+                                       }
+                                       if ( inCache ) {
+                                               if ( (fileSize != 0) && (segCmd->initprot == (VM_PROT_READ | VM_PROT_EXECUTE)) ) {
+                                                       if ( foundLoadCommandSegment )
+                                                               throw "load commands in multiple segments";
+                                                       foundLoadCommandSegment = true;
+                                               }
+                                       }
+                                       else if ( (fileStart < mh->sizeofcmds) && (fileSize != 0) ) {
+                                               // <rdar://problem/7942521> all load commands must be in an executable segment
+                                               if ( (fileStart != 0) || (fileSize < (mh->sizeofcmds+sizeof(macho_header))) )
+                                                       dyld::throwf("malformed mach-o image: segment %s does not span all load commands", segCmd->segname); 
+                                               if ( segCmd->initprot != (VM_PROT_READ | VM_PROT_EXECUTE) ) 
+                                                       dyld::throwf("malformed mach-o image: load commands found in segment %s with wrong permissions", segCmd->segname); 
+                                               if ( foundLoadCommandSegment )
+                                                       throw "load commands in multiple segments";
+                                               foundLoadCommandSegment = true;
+                                       }
+
+                                       const struct macho_section* const sectionsStart = (struct macho_section*)((char*)segCmd + sizeof(struct macho_segment_command));
+                                       const struct macho_section* const sectionsEnd = &sectionsStart[segCmd->nsects];
+                                       for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
+                                               if (!inCache && sect->offset != 0 && ((sect->offset + sect->size) > (segCmd->fileoff + segCmd->filesize)))
+                                                       dyld::throwf("malformed mach-o image: section %s,%s of '%s' exceeds segment %s booundary", sect->segname, sect->sectname, path, segCmd->segname);
+                                       }
+                               }
+                               break;
+                       case LC_SEGMENT_COMMAND_WRONG:
+                               dyld::throwf("malformed mach-o image: wrong LC_SEGMENT[_64] for architecture"); 
                                break;
                        case LC_LOAD_DYLIB:
                        case LC_LOAD_WEAK_DYLIB:
@@ -145,18 +227,68 @@ void ImageLoaderMachO::sniffLoadCommands(const macho_header* mh, const char* pat
                        case LC_CODE_SIGNATURE:
                                *codeSigCmd = (struct linkedit_data_command*)cmd; // only support one LC_CODE_SIGNATURE per image
                                break;
+                       case LC_ENCRYPTION_INFO:
+                       case LC_ENCRYPTION_INFO_64:
+                               *encryptCmd = (struct encryption_info_command*)cmd; // only support one LC_ENCRYPTION_INFO[_64] per image
+                               break;
                }
-               uint32_t cmdLength = cmd->cmdsize;
-               cmd = (const struct load_command*)(((char*)cmd)+cmdLength);
-               if ( cmd > endCmds ) {
-                       dyld::throwf("malformed mach-o image: load command #%d length (%u) would exceed sizeofcmds (%u) in %s", 
-                                                       i, cmdLength, mh->sizeofcmds, path);
+               cmd = nextCmd;
+       }
+
+       if ( context.codeSigningEnforced && !foundLoadCommandSegment )
+               throw "load commands not in a segment";
+
+       // <rdar://problem/13145644> verify every segment does not overlap another segment
+       if ( context.codeSigningEnforced ) {
+               uintptr_t lastFileStart = 0;
+               uintptr_t linkeditFileStart = 0;
+               const struct load_command* cmd1 = startCmds;
+               for (uint32_t i = 0; i < cmd_count; ++i) {
+                       if ( cmd1->cmd == LC_SEGMENT_COMMAND ) {
+                               struct macho_segment_command* segCmd1 = (struct macho_segment_command*)cmd1;
+                               uintptr_t vmStart1   = segCmd1->vmaddr;
+                               uintptr_t vmEnd1     = segCmd1->vmaddr + segCmd1->vmsize;
+                               uintptr_t fileStart1 = segCmd1->fileoff;
+                               uintptr_t fileEnd1   = segCmd1->fileoff + segCmd1->filesize;
+
+                               if (fileStart1 > lastFileStart)
+                                       lastFileStart = fileStart1;
+
+                               if ( strcmp(&segCmd1->segname[0], "__LINKEDIT") == 0 ) {
+                                       linkeditFileStart = fileStart1;
+                               }
+
+                               const struct load_command* cmd2 = startCmds;
+                               for (uint32_t j = 0; j < cmd_count; ++j) {
+                                       if ( cmd2 == cmd1 )
+                                               continue;
+                                       if ( cmd2->cmd == LC_SEGMENT_COMMAND ) {
+                                               struct macho_segment_command* segCmd2 = (struct macho_segment_command*)cmd2;
+                                               uintptr_t vmStart2   = segCmd2->vmaddr;
+                                               uintptr_t vmEnd2     = segCmd2->vmaddr + segCmd2->vmsize;
+                                               uintptr_t fileStart2 = segCmd2->fileoff;
+                                               uintptr_t fileEnd2   = segCmd2->fileoff + segCmd2->filesize;
+                                               if ( ((vmStart2 <= vmStart1) && (vmEnd2 > vmStart1) && (vmEnd1 > vmStart1)) 
+                                               || ((vmStart2 >= vmStart1) && (vmStart2 < vmEnd1) && (vmEnd2 > vmStart2)) )
+                                                       dyld::throwf("malformed mach-o image: segment %s vm overlaps segment %s", segCmd1->segname, segCmd2->segname);
+                                               if ( ((fileStart2 <= fileStart1) && (fileEnd2 > fileStart1) && (fileEnd1 > fileStart1))
+                                                 || ((fileStart2 >= fileStart1) && (fileStart2 < fileEnd1) && (fileEnd2 > fileStart2)) )
+                                                       dyld::throwf("malformed mach-o image: segment %s file content overlaps segment %s", segCmd1->segname, segCmd2->segname); 
+                                       }
+                                       cmd2 = (const struct load_command*)(((char*)cmd2)+cmd2->cmdsize);
+                               }
+                       }
+                       cmd1 = (const struct load_command*)(((char*)cmd1)+cmd1->cmdsize);
                }
+
+               if (lastFileStart != linkeditFileStart)
+                       dyld::throwf("malformed mach-o image: __LINKEDIT must be last segment");
        }
+
        // fSegmentsArrayCount is only 8-bits
        if ( *segCount > 255 )
                dyld::throwf("malformed mach-o image: more than 255 segments in %s", path);
-               
+
        // fSegmentsArrayCount is only 8-bits
        if ( *libCount > 4095 )
                dyld::throwf("malformed mach-o image: more than 4095 dependent libraries in %s", path);
@@ -176,12 +308,17 @@ ImageLoader* ImageLoaderMachO::instantiateMainExecutable(const macho_header* mh,
        unsigned int segCount;
        unsigned int libCount;
        const linkedit_data_command* codeSigCmd;
-       sniffLoadCommands(mh, path, &compressed, &segCount, &libCount, &codeSigCmd);
+       const encryption_info_command* encryptCmd;
+       sniffLoadCommands(mh, path, false, &compressed, &segCount, &libCount, context, &codeSigCmd, &encryptCmd);
        // instantiate concrete class based on content of load commands
        if ( compressed ) 
                return ImageLoaderMachOCompressed::instantiateMainExecutable(mh, slide, path, segCount, libCount, context);
        else
+#if SUPPORT_CLASSIC_MACHO
                return ImageLoaderMachOClassic::instantiateMainExecutable(mh, slide, path, segCount, libCount, context);
+#else
+               throw "missing LC_DYLD_INFO load command";
+#endif
 }
 
 
@@ -204,12 +341,17 @@ ImageLoader* ImageLoaderMachO::instantiateFromFile(const char* path, int fd, con
        unsigned int segCount;
        unsigned int libCount;
        const linkedit_data_command* codeSigCmd;
-       sniffLoadCommands((const macho_header*)fileData, path, &compressed, &segCount, &libCount, &codeSigCmd);
+       const encryption_info_command* encryptCmd;
+       sniffLoadCommands((const macho_header*)fileData, path, false, &compressed, &segCount, &libCount, context, &codeSigCmd, &encryptCmd);
        // instantiate concrete class based on content of load commands
        if ( compressed ) 
-               return ImageLoaderMachOCompressed::instantiateFromFile(path, fd, fileData, offsetInFat, lenInFat, info, segCount, libCount, codeSigCmd, context);
+               return ImageLoaderMachOCompressed::instantiateFromFile(path, fd, fileData, dataSize, offsetInFat, lenInFat, info, segCount, libCount, codeSigCmd, encryptCmd, context);
        else
-               return ImageLoaderMachOClassic::instantiateFromFile(path, fd, fileData, offsetInFat, lenInFat, info, segCount, libCount, codeSigCmd, context);
+#if SUPPORT_CLASSIC_MACHO
+               return ImageLoaderMachOClassic::instantiateFromFile(path, fd, fileData, dataSize, offsetInFat, lenInFat, info, segCount, libCount, codeSigCmd, context);
+#else
+               throw "missing LC_DYLD_INFO load command";
+#endif
 }
 
 // create image by using cached mach-o file
@@ -220,12 +362,17 @@ ImageLoader* ImageLoaderMachO::instantiateFromCache(const macho_header* mh, cons
        unsigned int segCount;
        unsigned int libCount;
        const linkedit_data_command* codeSigCmd;
-       sniffLoadCommands(mh, path, &compressed, &segCount, &libCount, &codeSigCmd);
+       const encryption_info_command* encryptCmd;
+       sniffLoadCommands(mh, path, true, &compressed, &segCount, &libCount, context, &codeSigCmd, &encryptCmd);
        // instantiate concrete class based on content of load commands
        if ( compressed ) 
                return ImageLoaderMachOCompressed::instantiateFromCache(mh, path, slide, info, segCount, libCount, context);
        else
+#if SUPPORT_CLASSIC_MACHO
                return ImageLoaderMachOClassic::instantiateFromCache(mh, path, slide, info, segCount, libCount, context);
+#else
+               throw "missing LC_DYLD_INFO load command";
+#endif
 }
 
 // create image by copying an in-memory mach-o file
@@ -235,26 +382,49 @@ ImageLoader* ImageLoaderMachO::instantiateFromMemory(const char* moduleName, con
        unsigned int segCount;
        unsigned int libCount;
        const linkedit_data_command* sigcmd;
-       sniffLoadCommands(mh, moduleName, &compressed, &segCount, &libCount, &sigcmd);
+       const encryption_info_command* encryptCmd;
+       sniffLoadCommands(mh, moduleName, false, &compressed, &segCount, &libCount, context, &sigcmd, &encryptCmd);
        // instantiate concrete class based on content of load commands
        if ( compressed ) 
                return ImageLoaderMachOCompressed::instantiateFromMemory(moduleName, mh, len, segCount, libCount, context);
        else
+#if SUPPORT_CLASSIC_MACHO
                return ImageLoaderMachOClassic::instantiateFromMemory(moduleName, mh, len, segCount, libCount, context);
+#else
+               throw "missing LC_DYLD_INFO load command";
+#endif
 }
 
 
+int ImageLoaderMachO::crashIfInvalidCodeSignature()
+{
+       // Now that segments are mapped in, try reading from first executable segment.
+       // If code signing is enabled the kernel will validate the code signature
+       // when paging in, and kill the process if invalid.
+       for(unsigned int i=0; i < fSegmentsCount; ++i) {
+               if ( (segFileOffset(i) == 0) && (segFileSize(i) != 0) ) {
+                       // return read value to ensure compiler does not optimize away load
+                       int* p = (int*)segActualLoadAddress(i);
+                       return *p;
+               }
+       }
+       return 0;
+}
+
 
-void ImageLoaderMachO::parseLoadCmds()
+void ImageLoaderMachO::parseLoadCmds(const LinkContext& context)
 {
        // now that segments are mapped in, get real fMachOData, fLinkEditBase, and fSlide
        for(unsigned int i=0; i < fSegmentsCount; ++i) {
                // set up pointer to __LINKEDIT segment
-               if ( strcmp(segName(i),"__LINKEDIT") == 0 ) 
+               if ( strcmp(segName(i),"__LINKEDIT") == 0 ) {
+                       if ( context.codeSigningEnforced && (segFileOffset(i) > fCoveredCodeLength))
+                               dyld::throwf("cannot load '%s' (segment outside of code signature)", this->getShortName());
                        fLinkEditBase = (uint8_t*)(segActualLoadAddress(i) - segFileOffset(i));
+               }
 #if TEXT_RELOC_SUPPORT
                // __TEXT segment always starts at beginning of file and contains mach_header and load commands
-               if ( strcmp(segName(i),"__TEXT") == 0 ) {
+               if ( segExecutable(i) ) {
                        if ( segHasRebaseFixUps(i) && (fSlide != 0) )
                                fTextSegmentRebases = true;
                        if ( segHasBindFixUps(i) )
@@ -287,6 +457,8 @@ void ImageLoaderMachO::parseLoadCmds()
        const dyld_info_command* dyldInfo = NULL;
        const macho_nlist* symbolTable = NULL;
        const char* symbolTableStrings = NULL;
+       const struct load_command* firstUnknownCmd = NULL;
+       const struct version_min_command* minOSVersionCmd = NULL;
        const dysymtab_command* dynSymbolTable = NULL;
        const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
        const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
@@ -334,9 +506,9 @@ void ImageLoaderMachO::parseLoadCmds()
                                                else if ( type == S_DTRACE_DOF )
                                                        fHasDOFSections = true;
                                                else if ( isTextSeg && (strcmp(sect->sectname, "__eh_frame") == 0) )
-                                                       fEHFrameSectionOffset = (uint8_t*)sect - fMachOData;
+                                                       fEHFrameSectionOffset = (uint32_t)((uint8_t*)sect - fMachOData);
                                                else if ( isTextSeg && (strcmp(sect->sectname, "__unwind_info") == 0) )
-                                                       fUnwindInfoSectionOffset = (uint8_t*)sect - fMachOData;;
+                                                       fUnwindInfoSectionOffset = (uint32_t)((uint8_t*)sect - fMachOData);
                                        }
                                }
                                break;
@@ -345,21 +517,43 @@ void ImageLoaderMachO::parseLoadCmds()
                                break;
                        case LC_ID_DYLIB:
                                {
-                                       fDylibIDOffset = (uint8_t*)cmd - fMachOData;
+                                       fDylibIDOffset = (uint32_t)((uint8_t*)cmd - fMachOData);
                                }
                                break;
                        case LC_RPATH:
                        case LC_LOAD_WEAK_DYLIB:
                    case LC_REEXPORT_DYLIB:
                        case LC_LOAD_UPWARD_DYLIB:
+                       case LC_MAIN:
                                // do nothing, just prevent LC_REQ_DYLD exception from occuring
                                break;
+                       case LC_VERSION_MIN_MACOSX:
+                       case LC_VERSION_MIN_IPHONEOS:
+                       case LC_VERSION_MIN_TVOS:
+                       case LC_VERSION_MIN_WATCHOS:
+                               minOSVersionCmd = (version_min_command*)cmd;
+                               break;
                        default:
-                               if ( (cmd->cmd & LC_REQ_DYLD) != 0 )
-                                       dyld::throwf("unknown required load command 0x%08X", cmd->cmd);
+                               if ( (cmd->cmd & LC_REQ_DYLD) != 0 ) {
+                                       if ( firstUnknownCmd == NULL )
+                                               firstUnknownCmd = cmd;
+                               }
+                               break;
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
        }
+       if ( firstUnknownCmd != NULL ) {
+               if ( minOSVersionCmd != NULL )  {
+                       dyld::throwf("cannot load '%s' because it was built for OS version %u.%u (load command 0x%08X is unknown)", 
+                                                this->getShortName(),
+                                                minOSVersionCmd->version >> 16, ((minOSVersionCmd->version >> 8) & 0xff), 
+                                                firstUnknownCmd->cmd);
+               }
+               else {
+                       dyld::throwf("cannot load '%s' (load command 0x%08X is unknown)", this->getShortName(), firstUnknownCmd->cmd);
+               }
+       }
+       
        
        if ( dyldInfo != NULL )
                this->setDyldInfo(dyldInfo);
@@ -477,6 +671,7 @@ uintptr_t ImageLoaderMachO::segActualEndAddress(unsigned int segIndex) const
 
 bool ImageLoaderMachO::segHasRebaseFixUps(unsigned int segIndex) const
 {
+#if TEXT_RELOC_SUPPORT
        // scan sections for fix-up bit
        const macho_segment_command* segCmd = segLoadCommand(segIndex);
        const struct macho_section* const sectionsStart = (struct macho_section*)((char*)segCmd + sizeof(struct macho_segment_command));
@@ -485,11 +680,13 @@ bool ImageLoaderMachO::segHasRebaseFixUps(unsigned int segIndex) const
                if ( (sect->flags & S_ATTR_LOC_RELOC) != 0 )
                        return true;
        }
+#endif
        return false;
 }
 
 bool ImageLoaderMachO::segHasBindFixUps(unsigned int segIndex) const
 {
+#if TEXT_RELOC_SUPPORT
        // scan sections for fix-up bit
        const macho_segment_command* segCmd = segLoadCommand(segIndex);
        const struct macho_section* const sectionsStart = (struct macho_section*)((char*)segCmd + sizeof(struct macho_segment_command));
@@ -498,6 +695,7 @@ bool ImageLoaderMachO::segHasBindFixUps(unsigned int segIndex) const
                if ( (sect->flags & S_ATTR_EXT_RELOC) != 0 )
                        return true;
        }
+#endif
        return false;
 }
 
@@ -547,7 +745,7 @@ void ImageLoaderMachO::preFetchDATA(int fd, uint64_t offsetInFat, const LinkCont
                                // prefetch writable segment that have mmap'ed regions
                                radvisory advice;
                                advice.ra_offset = offsetInFat + segFileOffset(i);
-                               advice.ra_count = segFileSize(i);
+                               advice.ra_count = (int)segFileSize(i);
                                // limit prefetch to 1MB (256 pages)
                                if ( advice.ra_count > 1024*1024 )
                                        advice.ra_count = 1024*1024;
@@ -646,19 +844,98 @@ void ImageLoaderMachO::setSlide(intptr_t slide)
        fSlide = slide;
 }
 
-#if CODESIGNING_SUPPORT
-void ImageLoaderMachO::loadCodeSignature(const struct linkedit_data_command* codeSigCmd, int fd,  uint64_t offsetInFatFile)
+void ImageLoaderMachO::loadCodeSignature(const struct linkedit_data_command* codeSigCmd, int fd,  uint64_t offsetInFatFile, const LinkContext& context)
 {
-       fsignatures_t siginfo;
-       siginfo.fs_file_start=offsetInFatFile;                  // start of mach-o slice in fat file 
-       siginfo.fs_blob_start=(void*)(codeSigCmd->dataoff);     // start of CD in mach-o file
-       siginfo.fs_blob_size=codeSigCmd->datasize;                      // size of CD
-       int result = fcntl(fd, F_ADDFILESIGS, &siginfo);
-       if ( result == -1 ) 
-               dyld::log("dyld: F_ADDFILESIGS failed for %s with errno=%d\n", this->getPath(), errno);
-       //dyld::log("dyld: registered code signature for %s\n", this->getPath());
+       // if dylib being loaded has no code signature load command
+       if ( codeSigCmd == NULL ) {
+#if __MAC_OS_X_VERSION_MIN_REQUIRED
+               bool codeSigningEnforced = context.codeSigningEnforced;
+               if ( context.mainExecutableCodeSigned && !codeSigningEnforced ) {
+                       static bool codeSignEnforcementDynamicallyEnabled = false;
+                       if ( !codeSignEnforcementDynamicallyEnabled ) {
+                               uint32_t flags;
+                               if ( csops(0, CS_OPS_STATUS, &flags, sizeof(flags)) != -1 ) {
+                                       if ( flags & CS_ENFORCEMENT ) {
+                                               codeSignEnforcementDynamicallyEnabled = true;
+                                       }
+                               }
+                       }
+                       codeSigningEnforced = codeSignEnforcementDynamicallyEnabled;
+               }
+               // if we require dylibs to be code signed
+               if ( codeSigningEnforced  ) {
+                       // if there is a non-load command based code signature, use it
+                       off_t offset = (off_t)offsetInFatFile;
+                       if ( fcntl(fd, F_FINDSIGS, &offset, sizeof(offset)) != -1 )
+                               return;
+                       // otherwise gracefully return from dlopen()
+                       dyld::throwf("required code signature missing for '%s'\n", this->getPath());
+               }
+#endif
+               //Since we don't have a range for the signature we have to assume full coverage
+               fCoveredCodeLength = UINT64_MAX;
+       }
+       else {
+#if __MAC_OS_X_VERSION_MIN_REQUIRED
+               // <rdar://problem/13622786> ignore code signatures in binaries built with pre-10.9 tools
+               if ( this->sdkVersion() < DYLD_MACOSX_VERSION_10_9 ) {
+                       return;
+               }
+#endif
+               fsignatures_t siginfo;
+               siginfo.fs_file_start=offsetInFatFile;                          // start of mach-o slice in fat file 
+               siginfo.fs_blob_start=(void*)(long)(codeSigCmd->dataoff);       // start of CD in mach-o file
+               siginfo.fs_blob_size=codeSigCmd->datasize;                      // size of CD
+               int result = fcntl(fd, F_ADDFILESIGS_RETURN, &siginfo);
+
+#if TARGET_IPHONE_SIMULATOR
+               // rdar://problem/18759224> check range covered by the code directory after loading
+               // Attempt to fallback only if we are in the simulator
+
+               if ( result == -1 ) {
+                       result = fcntl(fd, F_ADDFILESIGS, &siginfo);
+                       siginfo.fs_file_start = codeSigCmd->dataoff;
+               }
+#endif
+
+               if ( result == -1 ) {
+                       if ( (errno == EPERM) || (errno == EBADEXEC) )
+                               dyld::throwf("code signature invalid for '%s'\n", this->getPath());
+                       if ( context.verboseCodeSignatures ) 
+                               dyld::log("dyld: Failed registering code signature for %s, errno=%d\n", this->getPath(), errno);
+                       siginfo.fs_file_start = UINT64_MAX;
+               } else if ( context.verboseCodeSignatures )  {
+                       dyld::log("dyld: Registered code signature for %s\n", this->getPath());
+               }
+               fCoveredCodeLength = siginfo.fs_file_start;
+       }
 }
+
+void ImageLoaderMachO::validateFirstPages(const struct linkedit_data_command* codeSigCmd, int fd, const uint8_t *fileData, size_t lenFileData, off_t offsetInFat, const LinkContext& context)
+{
+#if __MAC_OS_X_VERSION_MIN_REQUIRED
+       // rdar://problem/21839703> 15A226d: dyld crashes in mageLoaderMachO::validateFirstPages during dlopen() after encountering an mmap failure
+       // We need to ignore older code signatures because they will be bad.
+       if ( this->sdkVersion() < DYLD_MACOSX_VERSION_10_9 ) {
+               return;
+       }
 #endif
+       if (codeSigCmd != NULL) {
+               if ( context.verboseMapping )
+                       dyld::log("dyld: validate pages: %llu\n", (unsigned long long)offsetInFat);
+
+               void *fdata = xmmap(NULL, lenFileData, PROT_READ | PROT_EXEC, MAP_SHARED, fd, offsetInFat);
+               if ( fdata == MAP_FAILED ) {
+                       if ( context.processRequiresLibraryValidation )
+                               dyld::throwf("cannot load image with wrong team ID in process using Library Validation");
+                       else
+                               dyld::throwf("mmap() errno=%d validating first page of '%s'", errno, getInstallPath());
+               }
+               if ( memcmp(fdata, fileData, lenFileData) != 0 )
+                       dyld::throwf("mmap() page compare failed for '%s'", getInstallPath());
+               munmap(fdata, lenFileData);
+       }
+}
 
 
 const char* ImageLoaderMachO::getInstallPath() const
@@ -673,11 +950,6 @@ const char* ImageLoaderMachO::getInstallPath() const
 void ImageLoaderMachO::registerInterposing()
 {
        // mach-o files advertise interposing by having a __DATA __interpose section
-       uintptr_t textStart = this->segActualLoadAddress(0);
-       uintptr_t textEnd = this->segActualEndAddress(0);
-       // <rdar://problem/8268602> verify that the first segment load command is for a read-only segment
-       if ( ! fGoodFirstSegment )
-               return;
        struct InterposeData { uintptr_t replacement; uintptr_t replacee; };
        const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
        const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
@@ -692,14 +964,16 @@ void ImageLoaderMachO::registerInterposing()
                                        for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
                                                if ( ((sect->flags & SECTION_TYPE) == S_INTERPOSING) || ((strcmp(sect->sectname, "__interpose") == 0) && (strcmp(seg->segname, "__DATA") == 0)) ) {
                                                        const InterposeData* interposeArray = (InterposeData*)(sect->addr + fSlide);
-                                                       const unsigned int count = sect->size / sizeof(InterposeData);
-                                                       for (uint32_t i=0; i < count; ++i) {
+                                                       const size_t count = sect->size / sizeof(InterposeData);
+                                                       for (size_t i=0; i < count; ++i) {
                                                                ImageLoader::InterposeTuple tuple;
                                                                tuple.replacement               = interposeArray[i].replacement;
-                                                               tuple.replacementImage  = this;
+                                                               tuple.neverImage                = this;
+                                                               tuple.onlyImage             = NULL;
                                                                tuple.replacee                  = interposeArray[i].replacee;
                                                                // <rdar://problem/7937695> verify that replacement is in this image
-                                                               if ( (tuple.replacement >= textStart) && (tuple.replacement < textEnd) ) {
+                                                               if ( this->containsAddress((void*)tuple.replacement) ) {
+                                                                       // chain to any existing interpositions
                                                                        for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
                                                                                if ( it->replacee == tuple.replacee ) {
                                                                                        tuple.replacee = it->replacement;
@@ -717,6 +991,72 @@ void ImageLoaderMachO::registerInterposing()
        }
 }
 
+uint32_t ImageLoaderMachO::sdkVersion() const
+{
+       const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
+       const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
+       const struct load_command* cmd = cmds;
+       const struct version_min_command* versCmd;
+       for (uint32_t i = 0; i < cmd_count; ++i) {
+               switch ( cmd->cmd ) {
+                       case LC_VERSION_MIN_MACOSX:
+                       case LC_VERSION_MIN_IPHONEOS:
+                       case LC_VERSION_MIN_TVOS:
+                       case LC_VERSION_MIN_WATCHOS:
+                               versCmd = (version_min_command*)cmd;
+                               return versCmd->sdk;
+               }
+               cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+       }
+       return 0;
+}
+
+uint32_t ImageLoaderMachO::minOSVersion(const mach_header* mh)
+{
+       const uint32_t cmd_count = mh->ncmds;
+       const struct load_command* const cmds = (struct load_command*)(((char*)mh) + sizeof(macho_header));
+       const struct load_command* cmd = cmds;
+       const struct version_min_command* versCmd;
+       for (uint32_t i = 0; i < cmd_count; ++i) {
+               switch ( cmd->cmd ) {
+                       case LC_VERSION_MIN_MACOSX:
+                       case LC_VERSION_MIN_IPHONEOS:
+                       case LC_VERSION_MIN_TVOS:
+                       case LC_VERSION_MIN_WATCHOS:
+                               versCmd = (version_min_command*)cmd;
+                               return versCmd->version;
+               }
+               cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+       }
+       return 0;
+}
+
+uint32_t ImageLoaderMachO::minOSVersion() const
+{
+       return ImageLoaderMachO::minOSVersion(machHeader());
+}
+
+
+void* ImageLoaderMachO::getThreadPC() const
+{
+       const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
+       const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
+       const struct load_command* cmd = cmds;
+       for (uint32_t i = 0; i < cmd_count; ++i) {
+               if ( cmd->cmd == LC_MAIN ) {
+                       entry_point_command* mainCmd = (entry_point_command*)cmd;
+                       void* entry = (void*)(mainCmd->entryoff + (char*)fMachOData);
+                       // <rdar://problem/8543820&9228031> verify entry point is in image
+                       if ( this->containsAddress(entry) )
+                               return entry;
+                       else
+                               throw "LC_MAIN entryoff is out of range";
+               }
+               cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+       }
+       return NULL;
+}
+
 
 void* ImageLoaderMachO::getMain() const
 {
@@ -727,30 +1067,31 @@ void* ImageLoaderMachO::getMain() const
                switch (cmd->cmd) {
                        case LC_UNIXTHREAD:
                        {
-                       #if __ppc__
-                               const ppc_thread_state_t* registers = (ppc_thread_state_t*)(((char*)cmd) + 16);
-                               return (void*)(registers->srr0 + fSlide);
-                       #elif __ppc64__
-                               const ppc_thread_state64_t* registers = (ppc_thread_state64_t*)(((char*)cmd) + 16);
-                               return (void*)(registers->srr0 + fSlide);
-                       #elif __i386__
+                       #if __i386__
                                const i386_thread_state_t* registers = (i386_thread_state_t*)(((char*)cmd) + 16);
-                               return (void*)(registers->eip + fSlide);
+                               void* entry = (void*)(registers->eip + fSlide);
                        #elif __x86_64__
                                const x86_thread_state64_t* registers = (x86_thread_state64_t*)(((char*)cmd) + 16);
-                               return (void*)(registers->rip + fSlide);
+                               void* entry = (void*)(registers->rip + fSlide);
                        #elif __arm__
                                const arm_thread_state_t* registers = (arm_thread_state_t*)(((char*)cmd) + 16);
-                               return (void*)(registers->__pc + fSlide);
+                               void* entry = (void*)(registers->__pc + fSlide);
+                       #elif __arm64__
+                               const arm_thread_state64_t* registers = (arm_thread_state64_t*)(((char*)cmd) + 16);
+                               void* entry = (void*)(registers->__pc + fSlide);
                        #else
                                #warning need processor specific code
                        #endif
+                               // <rdar://problem/8543820&9228031> verify entry point is in image
+                               if ( this->containsAddress(entry) ) {
+                                       return entry;
+                               }
                        }
                        break;
                }
                cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
        }
-       return NULL;
+       throw "no valid entry point";
 }
 
 bool ImageLoaderMachO::needsAddedLibSystemDepency(unsigned int libCount, const macho_header* mh)
@@ -860,8 +1201,8 @@ void ImageLoaderMachO::getRPaths(const LinkContext& context, std::vector<const c
                        case LC_RPATH:
                                const char* pathToAdd = NULL;
                                const char* path = (char*)cmd + ((struct rpath_command*)cmd)->path.offset;
-                               if ( strncmp(path, "@loader_path/", 13) == 0 ) {
-                                       if ( context.processIsRestricted  && (context.mainExecutable == this) ) {
+                               if ( (strncmp(path, "@loader_path", 12) == 0) && ((path[12] == '/') || (path[12] == '\0')) ) {
+                                       if ( context.processIsRestricted && !context.processRequiresLibraryValidation && (context.mainExecutable == this) ) {
                                                dyld::warn("LC_RPATH %s in %s being ignored in restricted program because of @loader_path\n", path, this->getPath());
                                                break;
                                        }
@@ -870,15 +1211,14 @@ void ImageLoaderMachO::getRPaths(const LinkContext& context, std::vector<const c
                                                char newRealPath[strlen(resolvedPath) + strlen(path)];
                                                strcpy(newRealPath, resolvedPath);
                                                char* addPoint = strrchr(newRealPath,'/');
-                                               if ( addPoint != NULL )
-                                                       strcpy(&addPoint[1], &path[13]);
-                                               else
-                                                       strcpy(newRealPath, &path[13]);
-                                               pathToAdd = strdup(newRealPath);
+                                               if ( addPoint != NULL ) {
+                                                       strcpy(addPoint, &path[12]);
+                                                       pathToAdd = strdup(newRealPath);
+                                               }
                                        }
                                }
-                               else if ( strncmp(path, "@executable_path/", 17) == 0 ) {
-                                       if ( context.processIsRestricted ) {
+                               else if ( (strncmp(path, "@executable_path", 16) == 0) && ((path[16] == '/') || (path[16] == '\0')) ) {
+                                       if ( context.processIsRestricted && !context.processRequiresLibraryValidation ) {
                                                dyld::warn("LC_RPATH %s in %s being ignored in restricted program because of @executable_path\n", path, this->getPath());
                                                break;
                                        }
@@ -887,14 +1227,13 @@ void ImageLoaderMachO::getRPaths(const LinkContext& context, std::vector<const c
                                                char newRealPath[strlen(resolvedPath) + strlen(path)];
                                                strcpy(newRealPath, resolvedPath);
                                                char* addPoint = strrchr(newRealPath,'/');
-                                               if ( addPoint != NULL )
-                                                       strcpy(&addPoint[1], &path[17]);
-                                               else
-                                                       strcpy(newRealPath, &path[17]);
-                                               pathToAdd = strdup(newRealPath);
+                                               if ( addPoint != NULL ) {
+                                                       strcpy(addPoint, &path[16]);
+                                                       pathToAdd = strdup(newRealPath);
+                                               }
                                        }
                                }
-                               else if ( (path[0] != '/') && context.processIsRestricted ) {
+                               else if ( (path[0] != '/') && context.processIsRestricted && !context.processRequiresLibraryValidation ) {
                                        dyld::warn("LC_RPATH %s in %s being ignored in restricted program because it is a relative path\n", path, this->getPath());
                                        break;
                                }
@@ -904,8 +1243,8 @@ void ImageLoaderMachO::getRPaths(const LinkContext& context, std::vector<const c
                                        bool found = false;
                                        for(const char** rp = context.rootPaths; *rp != NULL; ++rp) {
                                                char newPath[PATH_MAX];
-                                               strcpy(newPath, *rp);
-                                               strcat(newPath, path);
+                                               strlcpy(newPath, *rp, PATH_MAX);
+                                               strlcat(newPath, path, PATH_MAX);
                                                struct stat stat_buf;
                                                if ( stat(newPath, &stat_buf) != -1 ) {
                                                        //dyld::log("combined DYLD_ROOT_PATH and LC_RPATH: %s\n", newPath);
@@ -931,6 +1270,7 @@ void ImageLoaderMachO::getRPaths(const LinkContext& context, std::vector<const c
        }
 }
 
+
 bool ImageLoaderMachO::getUUID(uuid_t uuid) const
 {
        const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
@@ -1010,22 +1350,21 @@ void ImageLoaderMachO::doRebase(const LinkContext& context)
 #if TEXT_RELOC_SUPPORT
 void ImageLoaderMachO::makeTextSegmentWritable(const LinkContext& context, bool writeable)
 {
-       int textSegmentIndex = 0;
        for(unsigned int i=0; i < fSegmentsCount; ++i) {
-               if ( strcmp(segName(i), "__TEXT") == 0 ) {
-                       textSegmentIndex = i;
-                       break;
+               if ( segExecutable(i) ) {
+                       if ( writeable ) {
+                               segMakeWritable(i, context);
+                       }
+                       else {
+                       #if !__i386__ && !__x86_64__
+                               // some processors require range to be invalidated before it is made executable
+                               sys_icache_invalidate((void*)segActualLoadAddress(i), segSize(textSegmentIndex));
+                       #endif
+                               segProtect(i, context);
+                       }
                }
        }
 
-       if ( writeable ) {
-               segMakeWritable(textSegmentIndex, context);
-       }
-       else {
-               // iPhoneOS requires range to be invalidated before it is made executable
-               sys_icache_invalidate((void*)segActualLoadAddress(textSegmentIndex), segSize(textSegmentIndex));
-               segProtect(textSegmentIndex, context);
-       }
 }
 #endif
 
@@ -1064,18 +1403,9 @@ uintptr_t ImageLoaderMachO::getExportedSymbolAddress(const Symbol* sym, const Li
 uintptr_t ImageLoaderMachO::getSymbolAddress(const Symbol* sym, const ImageLoader* requestor, 
                                                                                                const LinkContext& context, bool runResolver) const
 {
-       uintptr_t result = exportedSymbolAddress(context, sym, runResolver);
+       uintptr_t result = exportedSymbolAddress(context, sym, requestor, runResolver);
        // check for interposing overrides
-       for (std::vector<InterposeTuple>::iterator it=fgInterposingTuples.begin(); it != fgInterposingTuples.end(); it++) {
-               // replace all references to 'replacee' with 'replacement'
-               if ( (result == it->replacee) && (requestor != it->replacementImage) ) {
-                       if ( context.verboseInterposing ) {
-                               dyld::log("dyld interposing: replace 0x%lX with 0x%lX in %s\n", 
-                                       it->replacee, it->replacement, this->getPath());
-                       }
-                       result = it->replacement;
-               }
-       }
+       result = interposedAddress(context, result, requestor);
        return result;
 }
 
@@ -1214,11 +1544,13 @@ bool ImageLoaderMachO::findSection(const void* imageInterior, const char** segme
 
 
 void __attribute__((noreturn)) ImageLoaderMachO::throwSymbolNotFound(const LinkContext& context, const char* symbol, 
-                                                                                                                                       const char* referencedFrom, const char* expectedIn)
+                                                                                                                                       const char* referencedFrom, const char* fromVersMismatch,
+                                                                                                                                       const char* expectedIn)
 {
        // record values for possible use by CrashReporter or Finder
        (*context.setErrorStrings)(dyld_error_kind_symbol_missing, referencedFrom, expectedIn, symbol);
-       dyld::throwf("Symbol not found: %s\n  Referenced from: %s\n  Expected in: %s\n", symbol, referencedFrom, expectedIn); 
+       dyld::throwf("Symbol not found: %s\n  Referenced from: %s%s\n  Expected in: %s\n",
+                                       symbol, referencedFrom, fromVersMismatch, expectedIn);
 }
 
 const mach_header* ImageLoaderMachO::machHeader() const
@@ -1286,7 +1618,7 @@ uintptr_t ImageLoaderMachO::bindLocation(const LinkContext& context, uintptr_t l
                        break;
                case BIND_TYPE_TEXT_PCREL32:
                        loc32 = (uint32_t*)locationToFix;
-                       value32 = (uint32_t)newValue - (((uintptr_t)locationToFix) + 4);
+                       value32 = (uint32_t)(newValue - (((uintptr_t)locationToFix) + 4));
                        if ( *loc32 != value32 )
                                *loc32 = value32;
                        break;
@@ -1306,15 +1638,13 @@ uintptr_t ImageLoaderMachO::bindLocation(const LinkContext& context, uintptr_t l
 
 #if SUPPORT_OLD_CRT_INITIALIZATION
 // first 16 bytes of "start" in crt1.o
-#if __ppc__
-       static uint32_t sStandardEntryPointInstructions[4] = { 0x7c3a0b78, 0x3821fffc, 0x54210034, 0x38000000 };
-#elif __i386__
+#if __i386__
        static uint8_t sStandardEntryPointInstructions[16] = { 0x6a, 0x00, 0x89, 0xe5, 0x83, 0xe4, 0xf0, 0x83, 0xec, 0x10, 0x8b, 0x5d, 0x04, 0x89, 0x5c, 0x24 };
 #endif
 #endif
 
 struct DATAdyld {
-       void*                   dyldLazyBinder;         // filled in at launch by dyld to point into dyld to &stub_binding_helper_interface
+       void*                   dyldLazyBinder;         // filled in at launch by dyld to point into dyld to &stub_binding_helper
        void*                   dyldFuncLookup;         // filled in at launch by dyld to point into dyld to &_dyld_func_lookup
        // the following only exist in main executables built for 10.5 or later
        ProgramVars             vars;
@@ -1322,7 +1652,6 @@ struct DATAdyld {
 
 // These are defined in dyldStartup.s
 extern "C" void stub_binding_helper();
-extern "C" bool dyld_func_lookup(const char* name, uintptr_t* address);
 
 
 void ImageLoaderMachO::setupLazyPointerHandler(const LinkContext& context)
@@ -1331,28 +1660,29 @@ void ImageLoaderMachO::setupLazyPointerHandler(const LinkContext& context)
        const uint32_t cmd_count = mh->ncmds;
        const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
        const struct load_command* cmd;
-       // set up __dyld section
-       // optimizations:
-       //   1) do nothing if image is in dyld shared cache and dyld loaded at same address as when cache built
-       //       2) first read __dyld value, if already correct don't write, this prevents dirtying a page
-       if ( !fInSharedCache || !context.dyldLoadedAtSameAddressNeededBySharedCache ) {
+       // There used to be some optimizations to skip this section scan, but we need to handle the 
+       // __dyld section in libdyld.dylib, so everything needs to be scanned for now.
+       // <rdar://problem/10910062> CrashTracer: 1,295 crashes in bash at bash: getenv
+       if ( true ) {
                cmd = cmds;
                for (uint32_t i = 0; i < cmd_count; ++i) {
                        if ( cmd->cmd == LC_SEGMENT_COMMAND ) {
                                const struct macho_segment_command* seg = (struct macho_segment_command*)cmd;
-                               if ( strcmp(seg->segname, "__DATA") == 0 ) {
+                               if ( strncmp(seg->segname, "__DATA", 6) == 0 ) {
                                        const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command));
                                        const struct macho_section* const sectionsEnd = &sectionsStart[seg->nsects];
                                        for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) {
                                                if ( strcmp(sect->sectname, "__dyld" ) == 0 ) {
                                                        struct DATAdyld* dd = (struct DATAdyld*)(sect->addr + fSlide);
+                               #if !__arm64__ && !__ARM_ARCH_7K__
                                                        if ( sect->size > offsetof(DATAdyld, dyldLazyBinder) ) {
                                                                if ( dd->dyldLazyBinder != (void*)&stub_binding_helper )
                                                                        dd->dyldLazyBinder = (void*)&stub_binding_helper;
                                                        }
+                               #endif // !__arm64__
                                                        if ( sect->size > offsetof(DATAdyld, dyldFuncLookup) ) {
-                                                               if ( dd->dyldFuncLookup != (void*)&dyld_func_lookup )
-                                                                       dd->dyldFuncLookup = (void*)&dyld_func_lookup;
+                                                               if ( dd->dyldFuncLookup != (void*)&_dyld_func_lookup )
+                                                                       dd->dyldFuncLookup = (void*)&_dyld_func_lookup;
                                                        }
                                                        if ( mh->filetype == MH_EXECUTE ) {
                                                                // there are two ways to get the program variables
@@ -1377,6 +1707,16 @@ void ImageLoaderMachO::setupLazyPointerHandler(const LinkContext& context)
                                #endif
                                                                }
                                                        }
+                                                       else if ( mh->filetype == MH_DYLIB ) {
+                                                               const char* installPath = this->getInstallPath();
+                                                               if ( (installPath != NULL) && (strncmp(installPath, "/usr/lib/", 9) == 0) ) {
+                                                                       if ( sect->size > offsetof(DATAdyld, vars) ) {
+                                                                               // use ProgramVars from libdyld.dylib but tweak mh field to correct value
+                                                                               dd->vars.mh = context.mainExecutable->machHeader();
+                                                                               context.setNewProgramVars(dd->vars);
+                                                                       }
+                                                               }
+                                                       }
                                                }
                                                else if ( (strcmp(sect->sectname, "__program_vars" ) == 0) && (mh->filetype == MH_EXECUTE) ) {
                                                        // this is a Mac OS X 10.6 or later main executable 
@@ -1451,16 +1791,6 @@ bool ImageLoaderMachO::usablePrebinding(const LinkContext& context) const
 void ImageLoaderMachO::doImageInit(const LinkContext& context)
 {
        if ( fHasDashInit ) {
-#if __IPHONE_OS_VERSION_MIN_REQUIRED   
-               // <rdar://problem/8543820> verify initializers are in first segment for dylibs
-               if ( this->isDylib() && !fGoodFirstSegment ) {
-                       if ( context.verboseInit )
-                               dyld::log("dyld: ignoring -init in %s\n", this->getPath());
-                       return;
-               }
-               uintptr_t textStart = this->segActualLoadAddress(0);
-               uintptr_t textEnd = this->segActualEndAddress(0);
-#endif
                const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
                const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
                const struct load_command* cmd = cmds;
@@ -1468,20 +1798,13 @@ void ImageLoaderMachO::doImageInit(const LinkContext& context)
                        switch (cmd->cmd) {
                                case LC_ROUTINES_COMMAND:
                                        Initializer func = (Initializer)(((struct macho_routines_command*)cmd)->init_address + fSlide);
-#if __IPHONE_OS_VERSION_MIN_REQUIRED   
-                                       // <rdar://problem/8543820> verify initializers are in first segment for dylibs
-                                       if ( this->isDylib() && (((uintptr_t)func >= textEnd) || ((uintptr_t)func < textStart)) ) {
-                                               if ( context.verboseInit )
-                                                       dyld::log("dyld: ignoring out of bounds initializer function %p in %s\n", func, this->getPath());
-                                       }
-                                       else {
-#endif
-                                               if ( context.verboseInit )
-                                                       dyld::log("dyld: calling -init function 0x%p in %s\n", func, this->getPath());
-                                               func(context.argc, context.argv, context.envp, context.apple, &context.programVars);
-#if __IPHONE_OS_VERSION_MIN_REQUIRED   
+                                       // <rdar://problem/8543820&9228031> verify initializers are in image
+                                       if ( ! this->containsAddress((void*)func) ) {
+                                               dyld::throwf("initializer function %p not in mapped image for %s\n", func, this->getPath());
                                        }
-#endif
+                                       if ( context.verboseInit )
+                                               dyld::log("dyld: calling -init function %p in %s\n", func, this->getPath());
+                                       func(context.argc, context.argv, context.envp, context.apple, &context.programVars);
                                        break;
                        }
                        cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
@@ -1492,16 +1815,6 @@ void ImageLoaderMachO::doImageInit(const LinkContext& context)
 void ImageLoaderMachO::doModInitFunctions(const LinkContext& context)
 {
        if ( fHasInitializers ) {
-#if __IPHONE_OS_VERSION_MIN_REQUIRED   
-               // <rdar://problem/8543820> verify initializers are in first segment for dylibs
-               if ( this->isDylib() && !fGoodFirstSegment ) {
-                       if ( context.verboseInit )
-                               dyld::log("dyld: ignoring all initializers in %s\n", this->getPath());
-                       return;
-               }
-               uintptr_t textStart = this->segActualLoadAddress(0);
-               uintptr_t textEnd = this->segActualEndAddress(0);
-#endif
                const uint32_t cmd_count = ((macho_header*)fMachOData)->ncmds;
                const struct load_command* const cmds = (struct load_command*)&fMachOData[sizeof(macho_header)];
                const struct load_command* cmd = cmds;
@@ -1514,23 +1827,16 @@ void ImageLoaderMachO::doModInitFunctions(const LinkContext& context)
                                        const uint8_t type = sect->flags & SECTION_TYPE;
                                        if ( type == S_MOD_INIT_FUNC_POINTERS ) {
                                                Initializer* inits = (Initializer*)(sect->addr + fSlide);
-                                               const uint32_t count = sect->size / sizeof(uintptr_t);
-                                               for (uint32_t i=0; i < count; ++i) {
+                                               const size_t count = sect->size / sizeof(uintptr_t);
+                                               for (size_t i=0; i < count; ++i) {
                                                        Initializer func = inits[i];
-#if __IPHONE_OS_VERSION_MIN_REQUIRED   
-                                                       // <rdar://problem/8543820> verify initializers are in first segment for dylibs
-                                                       if ( this->isDylib() && (((uintptr_t)func >= textEnd) || ((uintptr_t)func < textStart)) ) {
-                                                               if ( context.verboseInit )
-                                                                       dyld::log("dyld: ignoring out of bounds initializer function %p in %s\n", func, this->getPath());
-                                                       }
-                                                       else {
-#endif                                         
-                                                               if ( context.verboseInit )
-                                                                       dyld::log("dyld: calling initializer function %p in %s\n", func, this->getPath());
-                                                               func(context.argc, context.argv, context.envp, context.apple, &context.programVars);
-#if __IPHONE_OS_VERSION_MIN_REQUIRED   
+                                                       // <rdar://problem/8543820&9228031> verify initializers are in image
+                                                       if ( ! this->containsAddress((void*)func) ) {
+                                                               dyld::throwf("initializer function %p not in mapped image for %s\n", func, this->getPath());
                                                        }
-#endif
+                                                       if ( context.verboseInit )
+                                                               dyld::log("dyld: calling initializer function %p in %s\n", func, this->getPath());
+                                                       func(context.argc, context.argv, context.envp, context.apple, &context.programVars);
                                                }
                                        }
                                }
@@ -1617,9 +1923,13 @@ void ImageLoaderMachO::doTermination(const LinkContext& context)
                                        const uint8_t type = sect->flags & SECTION_TYPE;
                                        if ( type == S_MOD_TERM_FUNC_POINTERS ) {
                                                Terminator* terms = (Terminator*)(sect->addr + fSlide);
-                                               const uint32_t count = sect->size / sizeof(uintptr_t);
-                                               for (uint32_t i=count; i > 0; --i) {
+                                               const size_t count = sect->size / sizeof(uintptr_t);
+                                               for (size_t i=count; i > 0; --i) {
                                                        Terminator func = terms[i-1];
+                                                       // <rdar://problem/8543820&9228031> verify terminators are in image
+                                                       if ( ! this->containsAddress((void*)func) ) {
+                                                               dyld::throwf("termination function %p not in mapped image for %s\n", func, this->getPath());
+                                                       }
                                                        if ( context.verboseInit )
                                                                dyld::log("dyld: calling termination function %p in %s\n", func, this->getPath());
                                                        func();
@@ -1655,7 +1965,13 @@ intptr_t ImageLoaderMachO::assignSegmentAddresses(const LinkContext& context)
                uintptr_t highAddr = 0;
                for(unsigned int i=0, e=segmentCount(); i < e; ++i) {
                        const uintptr_t segLow = segPreferredLoadAddress(i);
-                       const uintptr_t segHigh = (segLow + segSize(i) + 4095) & -4096;
+                       const uintptr_t segHigh = dyld_page_round(segLow + segSize(i));
+                       if ( segLow < highAddr ) {
+                               if ( dyld_page_size > 4096 )
+                                       dyld::throwf("can't map segments into 16KB pages");
+                               else
+                                       dyld::throwf("overlapping segments");
+                       }
                        if ( segLow < lowAddr )
                                lowAddr = segLow;
                        if ( segHigh > highAddr )
@@ -1692,16 +2008,16 @@ uintptr_t ImageLoaderMachO::reserveAnAddressRange(size_t length, const ImageLoad
        // in PIE programs, load initial dylibs after main executable so they don't have fixed addresses either
        if ( fgNextPIEDylibAddress != 0 ) {
                 // add small (0-3 pages) random padding between dylibs
-               addr = fgNextPIEDylibAddress + (__stack_chk_guard/fgNextPIEDylibAddress & (sizeof(long)-1))*4096;
+               addr = fgNextPIEDylibAddress + (__stack_chk_guard/fgNextPIEDylibAddress & (sizeof(long)-1))*dyld_page_size;
                //dyld::log("padding 0x%08llX, guard=0x%08llX\n", (long long)(addr - fgNextPIEDylibAddress), (long long)(__stack_chk_guard));
-               kern_return_t r = vm_allocate(mach_task_self(), &addr, size, VM_FLAGS_FIXED);
+               kern_return_t r = vm_alloc(&addr, size, VM_FLAGS_FIXED | VM_MAKE_TAG(VM_MEMORY_DYLIB));
                if ( r == KERN_SUCCESS ) {
                        fgNextPIEDylibAddress = addr + size;
                        return addr;
                }
                fgNextPIEDylibAddress = 0;
        }
-       kern_return_t r = vm_allocate(mach_task_self(), &addr, size, VM_FLAGS_ANYWHERE);
+       kern_return_t r = vm_alloc(&addr, size, VM_FLAGS_ANYWHERE | VM_MAKE_TAG(VM_MEMORY_DYLIB));
        if ( r != KERN_SUCCESS ) 
                throw "out of address space";
        
@@ -1712,7 +2028,7 @@ bool ImageLoaderMachO::reserveAddressRange(uintptr_t start, size_t length)
 {
        vm_address_t addr = start;
        vm_size_t size = length;
-       kern_return_t r = vm_allocate(mach_task_self(), &addr, size, false /*only this range*/);
+       kern_return_t r = vm_alloc(&addr, size, VM_FLAGS_FIXED | VM_MAKE_TAG(VM_MEMORY_DYLIB));
        if ( r != KERN_SUCCESS ) 
                return false;
        return true;
@@ -1724,31 +2040,21 @@ void ImageLoaderMachO::mapSegments(int fd, uint64_t offsetInFat, uint64_t lenInF
 {
        // find address range for image
        intptr_t slide = this->assignSegmentAddresses(context);
-       if ( context.verboseMapping )
-               dyld::log("dyld: Mapping %s\n", this->getPath());
-       // <rdar://problem/8268602> verify that the first segment load command is for a r-x segment
-       // that starts at begining of file and is larger than all load commands
-       uintptr_t firstSegMappedStart = segPreferredLoadAddress(0) + slide;
-       uintptr_t firstSegMappedEnd = firstSegMappedStart + this->segSize(0);
-       if ( (this->segLoadCommand(0)->initprot == (VM_PROT_EXECUTE|VM_PROT_READ)) 
-               && (this->segFileOffset(0) == 0) 
-               && (this->segFileSize(0) != 0) 
-               && (this->segSize(0) > ((macho_header*)fMachOData)->sizeofcmds) ) {
-                       fGoodFirstSegment = true;
+       if ( context.verboseMapping ) {
+               if ( offsetInFat != 0 )
+                       dyld::log("dyld: Mapping %s (slice offset=%llu)\n", this->getPath(), (unsigned long long)offsetInFat);
+               else
+                       dyld::log("dyld: Mapping %s\n", this->getPath());
        }
        // map in all segments
        for(unsigned int i=0, e=segmentCount(); i < e; ++i) {
                vm_offset_t fileOffset = segFileOffset(i) + offsetInFat;
                vm_size_t size = segFileSize(i);
                uintptr_t requestedLoadAddress = segPreferredLoadAddress(i) + slide;
-               // <rdar://problem/8268602> verify other segments map after first
-               if ( (i != 0) && (requestedLoadAddress < firstSegMappedEnd) )
-                       fGoodFirstSegment = false;
                int protection = 0;
                if ( !segUnaccessible(i) ) {
                        // If has text-relocs, don't set x-bit initially.
                        // Instead set it later after text-relocs have been done.
-                       // The iPhone OS does not like it when you make executable code writable.
                        if ( segExecutable(i) && !(segHasRebaseFixUps(i) && (slide != 0)) )
                                protection   |= PROT_EXEC;
                        if ( segReadable(i) )
@@ -1767,7 +2073,7 @@ void ImageLoaderMachO::mapSegments(int fd, uint64_t offsetInFat, uint64_t lenInF
                                dyld::throwf("truncated mach-o error: segment %s extends to %llu which is past end of file %llu", 
                                                                segName(i), (uint64_t)(fileOffset+size), fileLen);
                        }
-                       void* loadAddress = mmap((void*)requestedLoadAddress, size, protection, MAP_FIXED | MAP_PRIVATE, fd, fileOffset);
+                       void* loadAddress = xmmap((void*)requestedLoadAddress, size, protection, MAP_FIXED | MAP_PRIVATE, fd, fileOffset);
                        if ( loadAddress == ((void*)(-1)) ) {
                                dyld::throwf("mmap() error %d at address=0x%08lX, size=0x%08lX segment=%s in Segment::map() mapping %s", 
                                        errno, requestedLoadAddress, (uintptr_t)size, segName(i), getPath());