X-Git-Url: https://git.saurik.com/apple/dyld.git/blobdiff_plain/bac542e65c0030c0d819c7ff1dcfc25892a61844..5f39f99244da210e6860ddd9fdd67baa46f62504:/src/dyldInitialization.cpp diff --git a/src/dyldInitialization.cpp b/src/dyldInitialization.cpp index 61b23b3..50d758d 100644 --- a/src/dyldInitialization.cpp +++ b/src/dyldInitialization.cpp @@ -1,6 +1,6 @@ /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*- * - * Copyright (c) 2004-2005 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2004-2008 Apple Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * @@ -27,31 +27,34 @@ #include #include #include +#include #include #include #include #include -#if __ppc__ || __ppc64__ - #include -#endif #if __x86_64__ #include #endif #include "dyld.h" +#include "dyldSyscallInterface.h" + +// from dyld_gdb.cpp +extern void addImagesToAllImages(uint32_t infoCount, const dyld_image_info info[]); +extern void syncProcessInfo(); #ifndef MH_PIE #define MH_PIE 0x200000 #endif +// currently dyld has no initializers, but if some come back, set this to non-zero +#define DYLD_INITIALIZER_SUPPORT 0 #if __LP64__ - #define macho_header mach_header_64 #define LC_SEGMENT_COMMAND LC_SEGMENT_64 #define macho_segment_command segment_command_64 #define macho_section section_64 #define RELOC_SIZE 3 #else - #define macho_header mach_header #define LC_SEGMENT_COMMAND LC_SEGMENT #define macho_segment_command segment_command #define macho_section section @@ -64,8 +67,10 @@ #define POINTER_RELOC GENERIC_RELOC_VANILLA #endif -// from dyld.cpp -namespace dyld { extern bool isRosetta(); }; + +#if TARGET_IPHONE_SIMULATOR +const dyld::SyscallHelpers* gSyscallHelpers = NULL; +#endif // @@ -76,8 +81,14 @@ namespace dyld { extern bool isRosetta(); }; namespace dyldbootstrap { + +#if DYLD_INITIALIZER_SUPPORT + typedef void (*Initializer)(int argc, const char* argv[], const char* envp[], const char* apple[]); +extern const Initializer inits_start __asm("section$start$__DATA$__mod_init_func"); +extern const Initializer inits_end __asm("section$end$__DATA$__mod_init_func"); + // // For a regular executable, the crt code calls dyld to run the executables initializers. // For a static executable, crt directly runs the initializers. @@ -85,35 +96,35 @@ typedef void (*Initializer)(int argc, const char* argv[], const char* envp[], co // We pass argc, argv, etc in case libc.a uses those arguments // static void runDyldInitializers(const struct macho_header* mh, intptr_t slide, int argc, const char* argv[], const char* envp[], const char* apple[]) +{ + for (const Initializer* p = &inits_start; p < &inits_end; ++p) { + (*p)(argc, argv, envp, apple); + } +} +#endif // DYLD_INITIALIZER_SUPPORT + + +// +// The kernel may have slid a Position Independent Executable +// +static uintptr_t slideOfMainExecutable(const struct macho_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; 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; - const struct macho_section* const sectionsStart = (struct macho_section*)((char*)seg + sizeof(struct macho_segment_command)); - const struct macho_section* const sectionsEnd = §ionsStart[seg->nsects]; - for (const struct macho_section* sect=sectionsStart; sect < sectionsEnd; ++sect) { - const uint8_t type = sect->flags & SECTION_TYPE; - if ( type == S_MOD_INIT_FUNC_POINTERS ){ - Initializer* inits = (Initializer*)(sect->addr + slide); - const uint32_t count = sect->size / sizeof(uintptr_t); - for (uint32_t i=0; i < count; ++i) { - Initializer func = inits[i]; - func(argc, argv, envp, apple); - } - } - } - } - break; + if ( cmd->cmd == LC_SEGMENT_COMMAND ) { + const struct macho_segment_command* segCmd = (struct macho_segment_command*)cmd; + if ( strcmp(segCmd->segname, "__TEXT") == 0 ) { + return (uintptr_t)mh - segCmd->vmaddr; + } } cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize); } + return 0; } + // // If the kernel does not load dyld at its preferred address, we need to apply // fixups to various initialized parts of the __DATA segment @@ -143,7 +154,7 @@ static void rebaseDyld(const struct macho_header* mh, intptr_t slide) const uint8_t type = sect->flags & SECTION_TYPE; if ( type == S_NON_LAZY_SYMBOL_POINTERS ) { // rebase non-lazy pointers (which all point internal to dyld, since dyld uses no shared libraries) - const uint32_t pointerCount = sect->size / sizeof(uintptr_t); + const uint32_t pointerCount = (uint32_t)(sect->size / sizeof(uintptr_t)); uintptr_t* const symbolPointers = (uintptr_t*)(sect->addr + slide); for (uint32_t j=0; j < pointerCount; ++j) { symbolPointers[j] += slide; @@ -172,10 +183,6 @@ static void rebaseDyld(const struct macho_header* mh, intptr_t slide) const relocation_info* const relocsStart = (struct relocation_info*)(linkEditSeg->vmaddr + slide + dynamicSymbolTable->locreloff - linkEditSeg->fileoff); const relocation_info* const relocsEnd = &relocsStart[dynamicSymbolTable->nlocrel]; for (const relocation_info* reloc=relocsStart; reloc < relocsEnd; ++reloc) { - #if __ppc__ || __ppc64__ || __i36__ - if ( (reloc->r_address & R_SCATTERED) != 0 ) - throw "scattered relocation in dyld"; - #endif if ( reloc->r_length != RELOC_SIZE ) throw "relocation in dyld has wrong size"; @@ -188,171 +195,27 @@ static void rebaseDyld(const struct macho_header* mh, intptr_t slide) } -// -// For some reason the kernel loads dyld with __TEXT and __LINKEDIT writable -// rdar://problem/3702311 -// -static void segmentProtectDyld(const struct macho_header* mh, intptr_t slide) -{ - 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; - 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; - vm_address_t addr = seg->vmaddr + slide; - vm_size_t size = seg->vmsize; - const bool setCurrentPermissions = false; - vm_protect(mach_task_self(), addr, size, setCurrentPermissions, seg->initprot); - //dyld::log("dyld: segment %s, 0x%08X -> 0x%08X, set to %d\n", seg->segname, addr, addr+size-1, seg->initprot); - } - break; - } - cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize); - } - -} - - -// -// re-map the main executable to a new random address -// -static const struct mach_header* randomizeExecutableLoadAddress(const struct mach_header* orgMH, uintptr_t* appsSlide) -{ -#if __ppc__ - // don't slide PIE programs running under rosetta - if ( dyld::isRosetta() ) - return orgMH; -#endif - // count segments - uint32_t segCount = 0; - const uint32_t cmd_count = orgMH->ncmds; - const struct load_command* const cmds = (struct load_command*)(((char*)orgMH)+sizeof(macho_header)); - const struct load_command* cmd = cmds; - for (uint32_t i = 0; i < cmd_count; ++i) { - if ( cmd->cmd == LC_SEGMENT_COMMAND ) { - const struct macho_segment_command* segCmd = (struct macho_segment_command*)cmd; - // page-zero and custom stacks don't move - if ( (strcmp(segCmd->segname, "__PAGEZERO") != 0) && (strcmp(segCmd->segname, "__UNIXSTACK") != 0) ) - ++segCount; - } - cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize); - } - - // make copy of segment info - macho_segment_command segs[segCount]; - uint32_t index = 0; - uintptr_t highestAddressUsed = 0; - uintptr_t lowestAddressUsed = UINTPTR_MAX; - cmd = cmds; - for (uint32_t i = 0; i < cmd_count; ++i) { - if ( cmd->cmd == LC_SEGMENT_COMMAND ) { - const struct macho_segment_command* segCmd = (struct macho_segment_command*)cmd; - if ( (strcmp(segCmd->segname, "__PAGEZERO") != 0) && (strcmp(segCmd->segname, "__UNIXSTACK") != 0) ) { - segs[index++] = *segCmd; - if ( (segCmd->vmaddr + segCmd->vmsize) > highestAddressUsed ) - highestAddressUsed = ((segCmd->vmaddr + segCmd->vmsize) + 4095) & -4096; - if ( segCmd->vmaddr < lowestAddressUsed ) - lowestAddressUsed = segCmd->vmaddr; - // do nothing if kernel has already randomized load address - if ( (strcmp(segCmd->segname, "__TEXT") == 0) && (segCmd->vmaddr != (uintptr_t)orgMH) ) - return orgMH; - } - } - cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize); - } - - // choose a random new base address -#if __LP64__ - uintptr_t highestAddressPossible = highestAddressUsed + 0x100000000ULL; -#else - uintptr_t highestAddressPossible = 0x80000000; -#endif - uintptr_t sizeNeeded = highestAddressUsed-lowestAddressUsed; - if ( (highestAddressPossible-sizeNeeded) < highestAddressUsed ) { - // new and old segments will overlap - // need better algorithm for remapping - // punt and don't re-map - return orgMH; - } - uintptr_t possibleRange = (highestAddressPossible-sizeNeeded) - highestAddressUsed; - uintptr_t newBaseAddress = highestAddressUsed + ((arc4random() % possibleRange) & -4096); - - vm_address_t addr = newBaseAddress; - // reserve new address range - if ( vm_allocate(mach_task_self(), &addr, sizeNeeded, VM_FLAGS_FIXED) == KERN_SUCCESS ) { - // copy each segment to new address - for (uint32_t i = 0; i < segCount; ++i) { - uintptr_t newSegAddress = segs[i].vmaddr - lowestAddressUsed + newBaseAddress; - if ( (vm_copy(mach_task_self(), segs[i].vmaddr, segs[i].vmsize, newSegAddress) != KERN_SUCCESS) - || (vm_protect(mach_task_self(), newSegAddress, segs[i].vmsize, true, segs[i].maxprot) != KERN_SUCCESS) - || (vm_protect(mach_task_self(), newSegAddress, segs[i].vmsize, false, segs[i].initprot) != KERN_SUCCESS) ) { - // can't copy so dealloc new region and run with original base address - vm_deallocate(mach_task_self(), newBaseAddress, sizeNeeded); - dyld::warn("could not relocate position independent exectable\n"); - return orgMH; - } - } - // unmap original segments - vm_deallocate(mach_task_self(), lowestAddressUsed, highestAddressUsed-lowestAddressUsed); - - // run with newly mapped executable - *appsSlide = newBaseAddress - lowestAddressUsed; - return (const struct mach_header*)newBaseAddress; - } - - // can't get new range, so don't slide to random address - return orgMH; -} - - -extern "C" void dyld_exceptions_init(const struct macho_header*, uintptr_t slide); // in dyldExceptions.cpp extern "C" void mach_init(); - -// -// _pthread_keys is partitioned in a lower part that dyld will use; libSystem -// will use the upper part. We set __pthread_tsd_first to 1 as the start of -// the lower part. Libc will take #1 and c++ exceptions will take #2. There -// is one free key=3 left. -// -extern "C" { - extern int __pthread_tsd_first; - extern void _pthread_keys_init(); -} +extern "C" void __guard_setup(const char* apple[]); // // This is code to bootstrap dyld. This work in normally done for a program by dyld and crt. // In dyld we have to do this manually. // -uintptr_t start(const struct mach_header* appsMachHeader, int argc, const char* argv[], intptr_t slide) +uintptr_t start(const struct macho_header* appsMachHeader, int argc, const char* argv[], + intptr_t slide, const struct macho_header* dyldsMachHeader, + uintptr_t* startGlue) { - // _mh_dylinker_header is magic symbol defined by static linker (ld), see - const struct macho_header* dyldsMachHeader = (const struct macho_header*)(((char*)&_mh_dylinker_header)+slide); - // if kernel had to slide dyld, we need to fix up load sensitive locations // we have to do this before using any global variables if ( slide != 0 ) { rebaseDyld(dyldsMachHeader, slide); } - - uintptr_t appsSlide = 0; - - // set pthread keys to dyld range - __pthread_tsd_first = 1; - _pthread_keys_init(); - - // enable C++ exceptions to work inside dyld - dyld_exceptions_init(dyldsMachHeader, slide); - + // allow dyld to use mach messaging mach_init(); - // set protection on segments (has to be done after mach_init) - segmentProtectDyld(dyldsMachHeader, slide); - // kernel sets up env pointer to be just past end of agv array const char** envp = &argv[argc+1]; @@ -361,18 +224,55 @@ uintptr_t start(const struct mach_header* appsMachHeader, int argc, const char* while(*apple != NULL) { ++apple; } ++apple; + // set up random value for stack canary + __guard_setup(apple); + +#if DYLD_INITIALIZER_SUPPORT // run all C++ initializers inside dyld runDyldInitializers(dyldsMachHeader, slide, argc, argv, envp, apple); - - // if main executable was linked -pie, then randomize its load address - if ( appsMachHeader->flags & MH_PIE ) - appsMachHeader = randomizeExecutableLoadAddress(appsMachHeader, &appsSlide); - +#endif + // now that we are done bootstrapping dyld, call dyld's main - return dyld::_main(appsMachHeader, appsSlide, argc, argv, envp, apple); + uintptr_t appsSlide = slideOfMainExecutable(appsMachHeader); + return dyld::_main(appsMachHeader, appsSlide, argc, argv, envp, apple, startGlue); } +#if TARGET_IPHONE_SIMULATOR + +extern "C" uintptr_t start_sim(int argc, const char* argv[], const char* envp[], const char* apple[], + const macho_header* mainExecutableMH, const macho_header* dyldMH, uintptr_t dyldSlide, + const dyld::SyscallHelpers*, uintptr_t* startGlue); + + +uintptr_t start_sim(int argc, const char* argv[], const char* envp[], const char* apple[], + const macho_header* mainExecutableMH, const macho_header* dyldMH, uintptr_t dyldSlide, + const dyld::SyscallHelpers* sc, uintptr_t* startGlue) +{ + // if simulator dyld loaded slid, it needs to rebase itself + // we have to do this before using any global variables + if ( dyldSlide != 0 ) { + rebaseDyld(dyldMH, dyldSlide); + } + + // save table of syscall pointers + gSyscallHelpers = sc; + + // allow dyld to use mach messaging + mach_init(); + + // set up random value for stack canary + __guard_setup(apple); + + // setup gProcessInfo to point to host dyld's struct + dyld::gProcessInfo = (struct dyld_all_image_infos*)(sc->getProcessInfo()); + syncProcessInfo(); + + // now that we are done bootstrapping dyld, call dyld's main + uintptr_t appsSlide = slideOfMainExecutable(mainExecutableMH); + return dyld::_main(mainExecutableMH, appsSlide, argc, argv, envp, apple, startGlue); +} +#endif } // end of namespace