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Improve --strip-relocs

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- Remove .reloc section
- Enable for 64-bit images
- Abort if explicitly set on unsupported image
- Use with --force to remove ASLR / apply when imagebase < default
This commit is contained in:
bitraid 2021-04-25 20:15:07 +03:00 committed by Markus F.X.J. Oberhumer
parent 181c752488
commit 144010295e
3 changed files with 42 additions and 21 deletions
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2
src/p_w64pep.cpp
View File

@ -268,8 +268,6 @@ void PackW64Pep::defineSymbols(unsigned ncsection, unsigned upxsection,
void PackW64Pep::pack(OutputFile *fo)
{
// FIXME: Relocation stripping disabled for now - Stefan Widmann
opt->win32_pe.strip_relocs = false;
super::pack0(fo, 0x0c, 0x0000000140000000ULL);
}

58
src/pefile.cpp
View File

@ -363,7 +363,7 @@ void PeFile::Reloc::finish(upx_byte *&p,unsigned &siz)
void PeFile::processRelocs(Reloc *rel) // pass2
{
rel->finish(oxrelocs,soxrelocs);
if (opt->win32_pe.strip_relocs && !isdll /*FIXME ASLR*/)
if (opt->win32_pe.strip_relocs)
soxrelocs = 0;
}
@ -377,10 +377,13 @@ void PeFile32::processRelocs() // pass1
const unsigned *counts = rel.getcounts();
const unsigned rnum = counts[1] + counts[2] + counts[3];
if ((opt->win32_pe.strip_relocs && !isdll) || rnum == 0)
if (opt->win32_pe.strip_relocs || rnum == 0)
{
if (IDSIZE(PEDIR_RELOC))
{
ibuf.fill(IDADDR(PEDIR_RELOC), IDSIZE(PEDIR_RELOC), FILLVAL);
ih.objects = tryremove(IDADDR(PEDIR_RELOC), ih.objects);
}
mb_orelocs.alloc(1);
orelocs = (upx_byte *)mb_orelocs.getVoidPtr();
sorelocs = 0;
@ -478,10 +481,13 @@ void PeFile64::processRelocs() // pass1
for (ic = 1; ic < 16; ic++)
rnum += counts[ic];
if ((opt->win32_pe.strip_relocs && !isdll) || rnum == 0)
if (opt->win32_pe.strip_relocs || rnum == 0)
{
if (IDSIZE(PEDIR_RELOC))
{
ibuf.fill(IDADDR(PEDIR_RELOC), IDSIZE(PEDIR_RELOC), FILLVAL);
ih.objects = tryremove(IDADDR(PEDIR_RELOC), ih.objects);
}
mb_orelocs.alloc(1);
orelocs = (upx_byte *)mb_orelocs.getVoidPtr();
sorelocs = 0;
@ -2161,21 +2167,40 @@ void PeFile::checkHeaderValues(unsigned subsystem, unsigned mask,
unsigned PeFile::handleStripRelocs(upx_uint64_t ih_imagebase,
upx_uint64_t default_imagebase,
unsigned dllflags)
LE16 &dllflags)
{
if (dllflags & IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE)
opt->win32_pe.strip_relocs = false;
else if (isdll) //do never strip relocations from DLLs
opt->win32_pe.strip_relocs = false;
else if (opt->win32_pe.strip_relocs < 0)
opt->win32_pe.strip_relocs = (ih_imagebase >= default_imagebase);
if (opt->win32_pe.strip_relocs < 0)
{
if (isdll || dllflags & IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE)
opt->win32_pe.strip_relocs = false;
else
opt->win32_pe.strip_relocs = ih_imagebase >= default_imagebase;
}
if (opt->win32_pe.strip_relocs)
{
if (ih_imagebase < default_imagebase)
throwCantPack("--strip-relocs is not allowed with this imagebase");
else
return RELOCS_STRIPPED;
if (isdll)
throwCantPack("--strip-relocs is not allowed with DLL images");
if (dllflags & IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE)
{
if (opt->force) // Disable ASLR
{
// The bit is set, so clear it with XOR
dllflags ^= IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE;
// HIGH_ENTROPY_VA has no effect without DYNAMIC_BASE, so clear
// it also if set
dllflags &= ~(unsigned)IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA;
}
else
throwCantPack("--strip-relocs is not allowed with ASLR (use "
"with --force to remove)");
}
if (!opt->force && ih_imagebase < default_imagebase)
throwCantPack("--strip-relocs may not support this imagebase (try "
"with --force)");
return RELOCS_STRIPPED;
}
else
info("Base relocations stripping is disabled for this image");
return 0;
}
@ -2319,9 +2344,6 @@ void PeFile::pack0(OutputFile *fo, ht &ih, ht &oh,
throwCantPack(buf);
}
// FIXME: disabled: the uncompressor would not allocate enough memory
//objs = tryremove(IDADDR(PEDIR_RELOC),objs);
// FIXME: if the last object has a bss then this won't work
// newvsize = (isection[objs-1].vaddr + isection[objs-1].size + oam1) &~ oam1;
// temporary solution:
@ -2589,7 +2611,7 @@ void PeFile::pack0(OutputFile *fo, ht &ih, ht &oh,
if (rvamin < osection[0].rawdataptr)
throwCantPack("object alignment too small");
if (opt->win32_pe.strip_relocs && !isdll)
if (opt->win32_pe.strip_relocs)
oh.flags |= RELOCS_STRIPPED;
//for (ic = 0; ic < oh.filealign; ic += 4)

3
src/pefile.h
View File

@ -59,7 +59,7 @@ protected:
unsigned ih_entry, unsigned ih_filealign);
unsigned handleStripRelocs(upx_uint64_t ih_imagebase,
upx_uint64_t default_imagebase,
unsigned dllflags);
LE16 &dllflags);
virtual bool handleForceOption() = 0;
virtual void callCompressWithFilters(Filter &, int filter_strategy,
@ -270,6 +270,7 @@ protected:
//NEW: DLL characteristics definition for ASLR, ... - Stefan Widmann
enum {
IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA = 0x0020,
IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE = 0x0040,
IMAGE_DLLCHARACTERISTICS_FORCE_INTEGRITY = 0x0080,
IMAGE_DLLCHARACTERISTICS_NX_COMPAT = 0x0100,