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Android shlib: work in progress

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modified:   p_lx_elf.cpp
	modified:   p_lx_elf.h
This commit is contained in:
John Reiser 2017-12-31 22:40:57 -08:00
parent edde6210f1
commit f5fd94e815
2 changed files with 145 additions and 33 deletions
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172
src/p_lx_elf.cpp
View File

@ -268,8 +268,8 @@ PackLinuxElf32::PackLinuxElf32help1(InputFile *f)
alloc_file_image(file_image, file_size); alloc_file_image(file_image, file_size);
f->seek(0, SEEK_SET); f->seek(0, SEEK_SET);
f->readx(file_image, file_size); f->readx(file_image, file_size);
phdri= (Elf32_Phdr *)(e_phoff + file_image); // do not free() !! phdri= (Elf32_Phdr *)(e_phoff + file_image); // do not free() !!
shdri= (Elf32_Shdr const *)(e_shoff + file_image); // do not free() !! shdri= (Elf32_Shdr *)(e_shoff + file_image); // do not free() !!
sec_dynsym = elf_find_section_type(Elf32_Shdr::SHT_DYNSYM); sec_dynsym = elf_find_section_type(Elf32_Shdr::SHT_DYNSYM);
if (sec_dynsym) { if (sec_dynsym) {
unsigned t = get_te32(&sec_dynsym->sh_link); unsigned t = get_te32(&sec_dynsym->sh_link);
@ -559,9 +559,11 @@ off_t PackLinuxElf64::pack3(OutputFile *fo, Filter &ft)
fo->rewrite(&word, sizeof(word)); fo->rewrite(&word, sizeof(word));
flen = fo->seek(0, SEEK_END); flen = fo->seek(0, SEEK_END);
} }
ehdri.e_shnum = 0; if (!opt->o_unix.android_shlib) {
ehdri.e_shoff = 0; ehdri.e_shnum = 0;
ehdri.e_shstrndx = 0; ehdri.e_shoff = 0;
ehdri.e_shstrndx = 0;
}
} }
return flen; return flen;
} }
@ -703,8 +705,8 @@ PackLinuxElf64::PackLinuxElf64help1(InputFile *f)
alloc_file_image(file_image, file_size); alloc_file_image(file_image, file_size);
f->seek(0, SEEK_SET); f->seek(0, SEEK_SET);
f->readx(file_image, file_size); f->readx(file_image, file_size);
phdri= (Elf64_Phdr *)(e_phoff + file_image); // do not free() !! phdri= (Elf64_Phdr *)(e_phoff + file_image); // do not free() !!
shdri= (Elf64_Shdr const *)(e_shoff + file_image); // do not free() !! shdri= (Elf64_Shdr *)(e_shoff + file_image); // do not free() !!
sec_dynsym = elf_find_section_type(Elf64_Shdr::SHT_DYNSYM); sec_dynsym = elf_find_section_type(Elf64_Shdr::SHT_DYNSYM);
if (sec_dynsym) { if (sec_dynsym) {
unsigned t = get_te32(&sec_dynsym->sh_link); unsigned t = get_te32(&sec_dynsym->sh_link);
@ -1718,7 +1720,29 @@ bool PackLinuxElf32::canPack()
// Also allow __uClibc_main and __uClibc_start_main . // Also allow __uClibc_main and __uClibc_start_main .
if (Elf32_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) { if (Elf32_Ehdr::ET_DYN==get_te16(&ehdr->e_type)) {
// The DT_SYMTAB has no designated length. Read the whole file.
alloc_file_image(file_image, file_size);
fi->seek(0, SEEK_SET);
fi->readx(file_image, file_size);
memcpy(&ehdri, ehdr, sizeof(Elf32_Ehdr)); memcpy(&ehdri, ehdr, sizeof(Elf32_Ehdr));
phdri= (Elf32_Phdr *)((size_t)e_phoff + file_image); // do not free() !!
shdri= (Elf32_Shdr *)((size_t)e_shoff + file_image); // do not free() !!
sec_strndx = &shdri[get_te16(&ehdr->e_shstrndx)];
shstrtab = (char const *)(get_te32(&sec_strndx->sh_offset) + file_image);
sec_dynsym = elf_find_section_type(Elf32_Shdr::SHT_DYNSYM);
if (sec_dynsym)
sec_dynstr = get_te32(&sec_dynsym->sh_link) + shdri;
phdr= phdri;
for (int j= e_phnum; --j>=0; ++phdr)
if (Elf32_Phdr::PT_DYNAMIC==get_te32(&phdr->p_type)) {
dynseg= (Elf32_Dyn const *)(check_pt_dynamic(phdr) + file_image);
break;
}
// elf_find_dynamic() returns 0 if 0==dynseg.
dynstr= (char const *)elf_find_dynamic(Elf32_Dyn::DT_STRTAB);
dynsym= (Elf32_Sym const *)elf_find_dynamic(Elf32_Dyn::DT_SYMTAB);
if (Elf32_Dyn::DF_1_PIE & elf_unsigned_dynamic(Elf32_Dyn::DT_FLAGS_1) if (Elf32_Dyn::DF_1_PIE & elf_unsigned_dynamic(Elf32_Dyn::DT_FLAGS_1)
|| calls_crt1((Elf32_Rel const *)elf_find_dynamic(Elf32_Dyn::DT_REL), || calls_crt1((Elf32_Rel const *)elf_find_dynamic(Elf32_Dyn::DT_REL),
@ -1898,15 +1922,21 @@ PackLinuxElf64::canPack()
fi->seek(0, SEEK_SET); fi->seek(0, SEEK_SET);
fi->readx(file_image, file_size); fi->readx(file_image, file_size);
memcpy(&ehdri, ehdr, sizeof(Elf64_Ehdr)); memcpy(&ehdri, ehdr, sizeof(Elf64_Ehdr));
phdri= (Elf64_Phdr *)((size_t)e_phoff + file_image); // do not free() !! phdri= (Elf64_Phdr *)((size_t)e_phoff + file_image); // do not free() !!
shdri= (Elf64_Shdr const *)((size_t)e_shoff + file_image); // do not free() !! shdri= (Elf64_Shdr *)((size_t)e_shoff + file_image); // do not free() !!
//sec_strndx = &shdri[ehdr->e_shstrndx];
//shstrtab = (char const *)(sec_strndx->sh_offset + file_image);
sec_dynsym = elf_find_section_type(Elf64_Shdr::SHT_DYNSYM); sec_dynsym = elf_find_section_type(Elf64_Shdr::SHT_DYNSYM);
if (sec_dynsym) if (sec_dynsym)
sec_dynstr = get_te64(&sec_dynsym->sh_link) + shdri; sec_dynstr = get_te64(&sec_dynsym->sh_link) + shdri;
sec_strndx = &shdri[get_te16(&ehdr->e_shstrndx)];
shstrtab = (char const *)(get_te64(&sec_strndx->sh_offset) + file_image);
if (Elf64_Shdr::SHT_STRTAB != get_te32(&sec_strndx->sh_type)
|| 0!=strcmp((char const *)".shstrtab",
&shstrtab[get_te32(&sec_strndx->sh_name)]) ) {
throwCantPack("bad e_shstrndx");
}
phdr= phdri; phdr= phdri;
for (int j= e_phnum; --j>=0; ++phdr) for (int j= e_phnum; --j>=0; ++phdr)
if (Elf64_Phdr::PT_DYNAMIC==get_te32(&phdr->p_type)) { if (Elf64_Phdr::PT_DYNAMIC==get_te32(&phdr->p_type)) {
@ -1945,9 +1975,23 @@ PackLinuxElf64::canPack()
} }
Elf64_Shdr const *shdr = shdri; Elf64_Shdr const *shdr = shdri;
xct_va = ~0ull; xct_va = ~0ull;
for (int j= e_shnum; --j>=0; ++shdr) { if (e_shnum) {
if (Elf64_Shdr::SHF_EXECINSTR & get_te32(&shdr->sh_flags)) { for (int j= e_shnum; --j>=0; ++shdr) {
xct_va = umin64(xct_va, get_te64(&shdr->sh_addr)); if (Elf64_Shdr::SHF_EXECINSTR & get_te32(&shdr->sh_flags)) {
xct_va = umin64(xct_va, get_te64(&shdr->sh_addr));
}
}
}
else { // no Sections; use heuristics
uint64_t const strsz = elf_unsigned_dynamic(Elf64_Dyn::DT_STRSZ);
uint64_t const strtab = elf_unsigned_dynamic(Elf64_Dyn::DT_STRTAB);
uint64_t const relsz = elf_unsigned_dynamic(Elf64_Dyn::DT_RELSZ);
uint64_t const rel = elf_unsigned_dynamic(Elf64_Dyn::DT_REL);
uint64_t const init = elf_unsigned_dynamic(Elf64_Dyn::DT_INIT);
if ((init == (relsz + rel ) && rel == (strsz + strtab))
|| (init == (strsz + strtab) && strtab == (relsz + rel ))
) {
xct_va = init;
} }
} }
// Rely on 0==elf_unsigned_dynamic(tag) if no such tag. // Rely on 0==elf_unsigned_dynamic(tag) if no such tag.
@ -2463,7 +2507,7 @@ void PackLinuxElf32::pack1(OutputFile *fo, Filter & /*ft*/)
if (opt->o_unix.preserve_build_id) { if (opt->o_unix.preserve_build_id) {
Elf32_Shdr *shdr = NULL; Elf32_Shdr *shdr = NULL;
Elf32_Shdr const *tmp = shdri; Elf32_Shdr *tmp = shdri;
if (! shdri) { if (! shdri) {
shdr = New(Elf32_Shdr, e_shnum); shdr = New(Elf32_Shdr, e_shnum);
@ -2477,7 +2521,7 @@ void PackLinuxElf32::pack1(OutputFile *fo, Filter & /*ft*/)
} }
//set the shstrtab //set the shstrtab
sec_strndx = &shdri[ehdri.e_shstrndx]; sec_strndx = &shdri[get_te16(&ehdri.e_shstrndx)];
char *strtab = New(char, sec_strndx->sh_size); char *strtab = New(char, sec_strndx->sh_size);
fi->seek(0,SEEK_SET); fi->seek(0,SEEK_SET);
@ -2500,11 +2544,11 @@ void PackLinuxElf32::pack1(OutputFile *fo, Filter & /*ft*/)
memset(&shdrout,0,sizeof(shdrout)); memset(&shdrout,0,sizeof(shdrout));
//setup the build-id //setup the build-id
memcpy(&shdrout.shdr[1],buildid, sizeof(shdrout.shdr[1])); memcpy(&shdrout.shdr[1], buildid, sizeof(shdrout.shdr[1]));
shdrout.shdr[1].sh_name = 1; shdrout.shdr[1].sh_name = 1;
//setup the shstrtab //setup the shstrtab
memcpy(&shdrout.shdr[2],sec_strndx, sizeof(shdrout.shdr[2])); memcpy(&shdrout.shdr[2], sec_strndx, sizeof(shdrout.shdr[2]));
shdrout.shdr[2].sh_name = 20; shdrout.shdr[2].sh_name = 20;
shdrout.shdr[2].sh_size = 29; //size of our static shstrtab shdrout.shdr[2].sh_size = 29; //size of our static shstrtab
} }
@ -2620,7 +2664,7 @@ void PackLinuxElf64::pack1(OutputFile *fo, Filter & /*ft*/)
assert(e_phoff == sizeof(Elf64_Ehdr)); // checked by canPack() assert(e_phoff == sizeof(Elf64_Ehdr)); // checked by canPack()
sz_phdrs = e_phnum * get_te16(&ehdri.e_phentsize); sz_phdrs = e_phnum * get_te16(&ehdri.e_phentsize);
Elf64_Phdr const *phdr = phdri; Elf64_Phdr *phdr = phdri;
note_size = 0; note_size = 0;
for (unsigned j=0; j < e_phnum; ++phdr, ++j) { for (unsigned j=0; j < e_phnum; ++phdr, ++j) {
if (phdr->PT_NOTE64 == get_te32(&phdr->p_type)) { if (phdr->PT_NOTE64 == get_te32(&phdr->p_type)) {
@ -2655,11 +2699,79 @@ void PackLinuxElf64::pack1(OutputFile *fo, Filter & /*ft*/)
progid = 0; // getRandomId(); not useful, so do not clutter progid = 0; // getRandomId(); not useful, so do not clutter
if (0!=xct_off) { // shared library if (0!=xct_off) { // shared library
fi->seek(0, SEEK_SET);
fi->readx(ibuf, xct_off);
sz_elf_hdrs = xct_off; sz_elf_hdrs = xct_off;
fo->write(ibuf, xct_off); fo->write(file_image, xct_off); // all before the first SHF_EXECINSTR (typ ".plt")
if (opt->o_unix.android_shlib) {
// In order to pacify the runtime linker on Android "O",
// we splice-in a 4KiB page that contains an "extra" copy
// of the Shdr and shstrtab.
set_te64(&ehdri.e_shoff, sz_elf_hdrs);
fo->seek(0, SEEK_SET); fo->rewrite(&ehdri, sizeof(ehdri));
unsigned const delta = (1u<<12);
// Relocate Phdr
phdr = phdri;
for (int j = e_phnum; --j>=0; ++phdr) {
uint64_t offset = get_te64(&phdr->p_offset);
if (xct_off <= offset) {
set_te64(&phdr->p_offset, delta + offset);
uint64_t addr = get_te64(&phdr->p_paddr);
set_te64(&phdr->p_paddr, delta + addr);
addr = get_te64(&phdr->p_vaddr);
set_te64(&phdr->p_vaddr, delta + addr);
}
if (0==phdr->p_offset && Elf64_Phdr::PT_LOAD==get_te32(&phdr->p_type)) {
uint64_t size = get_te64(&phdr->p_filesz);
set_te64(&phdr->p_filesz, delta + size);
size = get_te64(&phdr->p_memsz);
set_te64(&phdr->p_memsz, delta + size);
}
}
fo->rewrite(phdri, e_phnum * sizeof(Elf64_Phdr));
// Relocate dynsym (DT_SYMTAB)
Elf64_Sym *sym = const_cast<Elf64_Sym *>(dynsym);
uint64_t off_dynsym = get_te64(&sec_dynsym->sh_offset);
uint64_t sz_dynsym = get_te64(&sec_dynsym->sh_size);
for (int j = sz_dynsym / sizeof(Elf64_Sym); --j>=0; ++sym) {
uint64_t symval = get_te64(&sym->st_value);
unsigned symsec = get_te16(&sym->st_shndx);
if (Elf64_Sym::SHN_UNDEF != symsec
&& Elf64_Sym::SHN_ABS != symsec
&& xct_off <= symval) {
set_te64(&sym->st_value, delta + symval);
}
}
fo->seek(off_dynsym, SEEK_CUR); fo->rewrite(dynsym, sz_dynsym);
// FIXME?: Relocate contents of PT_DYNAMIC ?
// Important stuff should be below xct_off
// FIXME: Relocate Elf64_Rela.r_offset
// New copy of Shdr, and relocated
Elf64_Shdr *shdr = shdri;
uint64_t sz_shstrtab = get_te64(&sec_strndx->sh_size);
for (int j = e_shnum; --j>=0; ++shdr) {
uint64_t offset = get_te64(&shdr->sh_offset);
if (xct_off <= offset) {
set_te64(&shdr->sh_offset, delta + offset);
uint64_t addr = get_te64(&shdr->sh_addr);
set_te64(&shdr->sh_addr, delta + addr);
}
}
set_te64(&sec_strndx->sh_offset, (e_shnum * sizeof(Elf64_Shdr)) + sz_elf_hdrs);
fo->seek(0, SEEK_END); fo->write(shdri, e_shnum * sizeof(Elf64_Shdr));
// New copy of Shdr[.e_shstrndx].[ sh_offset, +.sh_size )
fo->write(shstrtab, sz_shstrtab);
MemBuffer spacer(delta - (sz_shstrtab + e_shnum * sizeof(Elf64_Shdr)));
spacer.clear();
fo->write(spacer, spacer.getSize());
sz_elf_hdrs += delta;
xct_va += delta;
xct_off += delta;
}
memset(&linfo, 0, sizeof(linfo)); memset(&linfo, 0, sizeof(linfo));
fo->write(&linfo, sizeof(linfo)); fo->write(&linfo, sizeof(linfo));
} }
@ -2667,11 +2779,11 @@ void PackLinuxElf64::pack1(OutputFile *fo, Filter & /*ft*/)
// only execute if option present // only execute if option present
if (opt->o_unix.preserve_build_id) { if (opt->o_unix.preserve_build_id) {
// set this so we can use elf_find_section_name // set this so we can use elf_find_section_name
e_shnum = ehdri.e_shnum; e_shnum = get_te16(&ehdri.e_shnum);
// there is a class member similar to this, but I did not // there is a class member similar to this, but I did not
// want to assume it would be available // want to assume it would be available
Elf64_Shdr const *tmp = shdri; Elf64_Shdr *tmp = shdri;
Elf64_Shdr *shdr = NULL; Elf64_Shdr *shdr = NULL;
@ -2687,7 +2799,7 @@ void PackLinuxElf64::pack1(OutputFile *fo, Filter & /*ft*/)
} }
//set the shstrtab //set the shstrtab
sec_strndx = &shdri[ehdri.e_shstrndx]; sec_strndx = &shdri[get_te16(&ehdri.e_shstrndx)];
char *strtab = New(char, sec_strndx->sh_size); char *strtab = New(char, sec_strndx->sh_size);
fi->seek(0,SEEK_SET); fi->seek(0,SEEK_SET);
@ -2710,11 +2822,11 @@ void PackLinuxElf64::pack1(OutputFile *fo, Filter & /*ft*/)
memset(&shdrout,0,sizeof(shdrout)); memset(&shdrout,0,sizeof(shdrout));
//setup the build-id //setup the build-id
memcpy(&shdrout.shdr[1],buildid, sizeof(shdrout.shdr[1])); memcpy(&shdrout.shdr[1], buildid, sizeof(shdrout.shdr[1]));
shdrout.shdr[1].sh_name = 1; shdrout.shdr[1].sh_name = 1;
//setup the shstrtab //setup the shstrtab
memcpy(&shdrout.shdr[2],sec_strndx, sizeof(shdrout.shdr[2])); memcpy(&shdrout.shdr[2], sec_strndx, sizeof(shdrout.shdr[2]));
shdrout.shdr[2].sh_name = 20; shdrout.shdr[2].sh_name = 20;
shdrout.shdr[2].sh_size = 29; //size of our static shstrtab shdrout.shdr[2].sh_size = 29; //size of our static shstrtab
} }
@ -3235,7 +3347,7 @@ void PackLinuxElf64::pack4(OutputFile *fo, Filter &ft)
} }
if (0!=xct_off) { // shared library if (0!=xct_off) { // shared library
if (opt->o_unix.android_shlib && shdri) { // dlopen() checks Elf64_Shdr vs Elf64_Phdr if (0 && opt->o_unix.android_shlib && shdri) { // dlopen() checks Elf64_Shdr vs Elf64_Phdr
unsigned load0_hi = ~0u; unsigned load0_hi = ~0u;
Elf64_Phdr const *phdr = phdri; Elf64_Phdr const *phdr = phdri;
for (unsigned j = 0; j < e_phnum; ++j, ++phdr) { for (unsigned j = 0; j < e_phnum; ++j, ++phdr) {
@ -3865,7 +3977,7 @@ PackLinuxElf64::elf_find_dynamic(unsigned int key) const
&& Elf64_Dyn::DT_NULL!=dynp->d_tag; ++dynp) if (get_te64(&dynp->d_tag)==key) { && Elf64_Dyn::DT_NULL!=dynp->d_tag; ++dynp) if (get_te64(&dynp->d_tag)==key) {
upx_uint64_t const t= elf_get_offset_from_address(get_te64(&dynp->d_val)); upx_uint64_t const t= elf_get_offset_from_address(get_te64(&dynp->d_val));
if (t) { if (t) {
return (size_t)t + file_image; return &((unsigned char const *)file_image)[(size_t)t];
} }
break; break;
} }

6
src/p_lx_elf.h
View File

@ -157,7 +157,7 @@ protected:
protected: protected:
Elf32_Ehdr ehdri; // from input file Elf32_Ehdr ehdri; // from input file
Elf32_Phdr *phdri; // for input file Elf32_Phdr *phdri; // for input file
Elf32_Shdr const *shdri; // from input file Elf32_Shdr *shdri; // from input file
Elf32_Phdr const *gnu_stack; // propagate NX Elf32_Phdr const *gnu_stack; // propagate NX
unsigned e_phoff; unsigned e_phoff;
unsigned e_shoff; unsigned e_shoff;
@ -282,7 +282,7 @@ protected:
protected: protected:
Elf64_Ehdr ehdri; // from input file Elf64_Ehdr ehdri; // from input file
Elf64_Phdr *phdri; // for input file Elf64_Phdr *phdri; // for input file
Elf64_Shdr const *shdri; // from input file Elf64_Shdr *shdri; // from input file
Elf64_Phdr const *gnu_stack; // propagate NX Elf64_Phdr const *gnu_stack; // propagate NX
upx_uint64_t e_phoff; upx_uint64_t e_phoff;
upx_uint64_t e_shoff; upx_uint64_t e_shoff;
@ -299,7 +299,7 @@ protected:
Elf64_Sym const *jni_onload_sym; Elf64_Sym const *jni_onload_sym;
char const *shstrtab; // via Elf64_Shdr char const *shstrtab; // via Elf64_Shdr
Elf64_Shdr const *sec_strndx; Elf64_Shdr *sec_strndx;
Elf64_Shdr const *sec_dynsym; Elf64_Shdr const *sec_dynsym;
Elf64_Shdr const *sec_dynstr; Elf64_Shdr const *sec_dynstr;