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Mach-O dyld: __LINKEDIT must have highest .vmaddr and .fileoff

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jreiser@BitWagon.com 2016-09-10 15:46:36 -07:00 committed by Markus F.X.J. Oberhumer
parent 89df7451ef
commit 5bb6f246ed
1 changed files with 30 additions and 23 deletions
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53
src/p_mach.cpp
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@ -825,21 +825,21 @@ void PackMachAMD64::pack4(OutputFile *fo, Filter &ft) // append PackHeader
memcpy(&segLINK, segptr, sizeof(segLINK));
delta = offLINK - segLINK.fileoff; // relocation constant
// Mach_command __LINKEDIT
// The contents remain the same, but at a different offset in the file
// The contents for __LINKEDIT remain the same,
// but move to a different offset in the file
fo->seek(offLINK, SEEK_SET);
fo->write(&stub_amd64_darwin_macho_upxmain_exe[segLINK.fileoff], segLINK.filesize);
// Update the __LINKEDIT header
segLINK.vmaddr += delta;
segLINK.fileoff = offLINK;
fo->seek((char const *)ptr1 - (char const *)ptr0, SEEK_SET);
fo->rewrite(&segLINK, sizeof(segLINK));
// Mach_segment_command for new segXHDR
segXHDR.cmdsize = sizeof(segXHDR);
segXHDR.nsects = 0;
fo->seek((char const *)ptr1 - (char const *)ptr0, SEEK_SET);
fo->rewrite(&segXHDR, sizeof(segXHDR));
// Update the __LINKEDIT header
segLINK.vmaddr += delta;
segLINK.fileoff = offLINK;
fo->rewrite(&segLINK, sizeof(segLINK));
}
} break;
case Mach_segment_command::LC_DYLD_INFO_ONLY: {
@ -1640,25 +1640,32 @@ void PackMachBase<T>::pack1(OutputFile *const fo, Filter &/*ft*/) // generate e
unsigned cmdsize = mhdro.sizeofcmds - sizeof(segXHDR);
Mach_header const *const ptr0 = (Mach_header const *)stub_amd64_darwin_macho_upxmain_exe;
Mach_command const *ptr1 = (Mach_command const *)(1+ ptr0);
uint64_t next_va = 0;
uint64_t next_fpos = 0;
for (unsigned j = 0; j < mhdro.ncmds -1; ++j,
(cmdsize -= ptr1->cmdsize),
ptr1 = (Mach_command const *)(ptr1->cmdsize + (char const *)ptr1)) {
Mach_segment_command const *const segptr = (Mach_segment_command const *)ptr1;
if (lc_seg == ptr1->cmd && !strcmp("__LINKEDIT", segptr->segname)) {
// Mach_command before __LINKEDIT
fo->write((1+ ptr0), (char const *)ptr1 - (char const *)(1+ ptr0));
// Mach_command __LINKEDIT
fo->write(segptr, segptr->cmdsize);
// LC_SEGMENT_64 for payload; steal space from -Wl,-headerpadsize
segXHDR.cmdsize = sizeof(segXHDR);
segXHDR.nsects = 0;
fo->write(&segXHDR, sizeof(segXHDR));
// Mach_command after __LINKEDIT
fo->write(ptr1->cmdsize + (char const *)ptr1, cmdsize - ptr1->cmdsize);
// Contents before __LINKEDIT; put non-headers at same offset in file
unsigned pos = sizeof(mhdro) + mhdro.sizeofcmds; // includes sizeof(segXHDR)
fo->write(&stub_amd64_darwin_macho_upxmain_exe[pos], segptr->fileoff - pos);
break;
if (lc_seg == ptr1->cmd) {
if (!strcmp("__LINKEDIT", segptr->segname)) {
// Mach_command before __LINKEDIT
fo->write((1+ ptr0), (char const *)ptr1 - (char const *)(1+ ptr0));
// LC_SEGMENT_64 for UPX_DATA; steal space from -Wl,-headerpadsize
segXHDR.cmdsize = sizeof(segXHDR);
segXHDR.vmaddr = next_va;
segXHDR.fileoff = PAGE_MASK & (~PAGE_MASK + next_fpos);
segXHDR.maxprot = segXHDR.initprot = Mach_segment_command::VM_PROT_READ;
segXHDR.nsects = 0;
fo->write(&segXHDR, sizeof(segXHDR));
// Mach_command __LINKEDIT and after
fo->write((char const *)ptr1, cmdsize);
// Contents before __LINKEDIT; put non-headers at same offset in file
unsigned pos = sizeof(mhdro) + mhdro.sizeofcmds; // includes sizeof(segXHDR)
fo->write(&stub_amd64_darwin_macho_upxmain_exe[pos], segptr->fileoff - pos);
break;
}
next_va = segptr->vmsize + segptr->vmaddr;
next_fpos = segptr->filesize + segptr->fileoff;
}
}
}