Loading...
--- dyld/dyld-852.2/src/dyldInitialization.cpp
+++ dyld/dyld-95.3/src/dyldInitialization.cpp
@@ -1,6 +1,6 @@
/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
*
- * Copyright (c) 2004-2008 Apple Inc. All rights reserved.
+ * Copyright (c) 2004-2005 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
@@ -27,23 +27,45 @@
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
-#include <sys/mman.h>
#include <mach/mach.h>
-
-#include "dyld2.h"
-#include "dyldSyscallInterface.h"
-#include "MachOAnalyzer.h"
-#include "Tracing.h"
-
-// from libc.a
-extern "C" void mach_init();
-extern "C" void __guard_setup(const char* apple[]);
-extern "C" void _subsystem_init(const char* apple[]);
-
-// from dyld_debugger.cpp
-extern void syncProcessInfo();
-
-const dyld::SyscallHelpers* gSyscallHelpers = NULL;
+#include <mach-o/loader.h>
+#include <mach-o/ldsyms.h>
+#include <mach-o/reloc.h>
+#if __ppc__ || __ppc64__
+ #include <mach-o/ppc/reloc.h>
+#endif
+#if __x86_64__
+ #include <mach-o/x86_64/reloc.h>
+#endif
+#include "dyld.h"
+
+#ifndef MH_PIE
+ #define MH_PIE 0x200000
+#endif
+
+
+#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
+ #define RELOC_SIZE 2
+#endif
+
+#if __x86_64__
+ #define POINTER_RELOC X86_64_RELOC_UNSIGNED
+#else
+ #define POINTER_RELOC GENERIC_RELOC_VANILLA
+#endif
+
+// from dyld.cpp
+namespace dyld { extern bool isRosetta(); };
//
@@ -54,16 +76,7 @@
namespace dyldbootstrap {
-// currently dyld has no initializers, but if some come back, set this to non-zero
-#define DYLD_INITIALIZER_SUPPORT 0
-
-
-#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.
@@ -71,59 +84,275 @@
// dyld (should be static) but is a dynamic executable and needs this hack to run its own initializers.
// We pass argc, argv, etc in case libc.a uses those arguments
//
-static void runDyldInitializers(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
-
-
-//
-// On disk, all pointers in dyld's DATA segment are chained together.
-// They need to be fixed up to be real pointers to run.
-//
-static void rebaseDyld(const dyld3::MachOLoaded* dyldMH)
-{
- // walk all fixups chains and rebase dyld
- const dyld3::MachOAnalyzer* ma = (dyld3::MachOAnalyzer*)dyldMH;
- assert(ma->hasChainedFixups());
- uintptr_t slide = (long)ma; // all fixup chain based images have a base address of zero, so slide == load address
- __block Diagnostics diag;
- ma->withChainStarts(diag, 0, ^(const dyld_chained_starts_in_image* starts) {
- ma->fixupAllChainedFixups(diag, starts, slide, dyld3::Array<const void*>(), nullptr);
- });
- diag.assertNoError();
-
- // now that rebasing done, initialize mach/syscall layer
- mach_init();
-
- // <rdar://47805386> mark __DATA_CONST segment in dyld as read-only (once fixups are done)
- ma->forEachSegment(^(const dyld3::MachOFile::SegmentInfo& info, bool& stop) {
- if ( info.readOnlyData ) {
- ::mprotect(((uint8_t*)(dyldMH))+info.vmAddr, (size_t)info.vmSize, VM_PROT_READ);
- }
- });
-}
-
+static void runDyldInitializers(const struct macho_header* mh, intptr_t slide, int argc, const char* argv[], const char* envp[], const char* apple[])
+{
+ 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;
+ }
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+}
+
+//
+// If the kernel does not load dyld at its preferred address, we need to apply
+// fixups to various initialized parts of the __DATA segment
+//
+static void rebaseDyld(const struct macho_header* mh, intptr_t slide)
+{
+ // rebase non-lazy pointers (which all point internal to dyld, since dyld uses no shared libraries)
+ // and get interesting pointers into dyld
+ 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 macho_segment_command* linkEditSeg = NULL;
+#if __x86_64__
+ const struct macho_segment_command* firstWritableSeg = NULL;
+#endif
+ const struct dysymtab_command* dynamicSymbolTable = 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;
+ 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_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);
+ uintptr_t* const symbolPointers = (uintptr_t*)(sect->addr + slide);
+ for (uint32_t j=0; j < pointerCount; ++j) {
+ symbolPointers[j] += slide;
+ }
+ }
+ }
+#if __x86_64__
+ if ( (firstWritableSeg == NULL) && (seg->initprot & VM_PROT_WRITE) )
+ firstWritableSeg = seg;
+#endif
+ }
+ break;
+ case LC_DYSYMTAB:
+ dynamicSymbolTable = (struct dysymtab_command *)cmd;
+ break;
+ }
+ cmd = (const struct load_command*)(((char*)cmd)+cmd->cmdsize);
+ }
+
+ // use reloc's to rebase all random data pointers
+#if __x86_64__
+ const uintptr_t relocBase = firstWritableSeg->vmaddr + slide;
+#else
+ const uintptr_t relocBase = (uintptr_t)mh;
+#endif
+ 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";
+
+ if ( reloc->r_type != POINTER_RELOC )
+ throw "relocation in dyld has wrong type";
+
+ // update pointer by amount dyld slid
+ *((uintptr_t*)(reloc->r_address + relocBase)) += 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();
+}
//
// 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 dyld3::MachOLoaded* appsMachHeader, int argc, const char* argv[],
- const dyld3::MachOLoaded* dyldsMachHeader, uintptr_t* startGlue)
-{
-
- // Emit kdebug tracepoint to indicate dyld bootstrap has started <rdar://46878536>
- dyld3::kdebug_trace_dyld_marker(DBG_DYLD_TIMING_BOOTSTRAP_START, 0, 0, 0, 0);
-
+uintptr_t start(const struct mach_header* appsMachHeader, int argc, const char* argv[], intptr_t slide)
+{
+ // _mh_dylinker_header is magic symbol defined by static linker (ld), see <mach-o/ldsyms.h>
+ 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
- rebaseDyld(dyldsMachHeader);
-
+ 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];
@@ -132,51 +361,18 @@
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(argc, argv, envp, apple);
-#endif
-
- _subsystem_init(apple);
-
+ 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);
+
// now that we are done bootstrapping dyld, call dyld's main
- uintptr_t appsSlide = appsMachHeader->getSlide();
- return dyld::_main((macho_header*)appsMachHeader, appsSlide, argc, argv, envp, apple, startGlue);
-}
-
-
-#if TARGET_OS_SIMULATOR
-
-extern "C" uintptr_t start_sim(int argc, const char* argv[], const char* envp[], const char* apple[],
- const dyld3::MachOLoaded* mainExecutableMH, const dyld3::MachOLoaded* 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 dyld3::MachOLoaded* mainExecutableMH, const dyld3::MachOLoaded* dyldSimMH, uintptr_t dyldSlide,
- const dyld::SyscallHelpers* sc, uintptr_t* startGlue)
-{
- // save table of syscall pointers
- gSyscallHelpers = sc;
-
- // dyld_sim uses chained rebases, so it always need to be fixed up
- rebaseDyld(dyldSimMH);
-
- // 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 = mainExecutableMH->getSlide();
- return dyld::_main((macho_header*)mainExecutableMH, appsSlide, argc, argv, envp, apple, startGlue);
-}
-#endif
+ return dyld::_main(appsMachHeader, appsSlide, argc, argv, envp, apple);
+}
+
+
} // end of namespace