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put overlay into PT_LOAD, in order to protect from /usr/bin/strip,

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and prepare to discontinue use of /proc/exe by stub
	p_unix.cpp p_unix.h stub/Makefile
	stub/l_lx_exec86.lds

committer: jreiser <jreiser> 958837765 +0000
This commit is contained in:
John Reiser
2000-05-20 15:49:25 +00:00
parent e6e9229942
commit 7854a924c7
4 changed files with 64 additions and 16 deletions
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src/p_unix.cpp
+31 -2
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@@ -191,6 +191,8 @@ void PackUnix::pack(OutputFile *fo)
set_native32(obuf, lsize);
fo->write(obuf, 4);
updateLoader(fo);
// finally check compression ratio
if (!Packer::checkCompressionRatio(fo->getBytesWritten(), ph.u_len))
throwNotCompressible();
@@ -425,13 +427,14 @@ void PackLinuxI386::patchLoader()
patchVersion(loader,lsize);
// The beginning of our loader consists of a elf_hdr (52 bytes) and
// two sections elf_phdr (2 * 32 byte), so we have 12 free bytes
// one section elf_phdr (32 byte) now,
// another section elf_phdr (32 byte) later, so we have 12 free bytes
// from offset 116 to the program start at offset 128.
assert(get_le32(loader + 28) == 52); // e_phoff
assert(get_le32(loader + 32) == 0); // e_shoff
assert(get_le16(loader + 40) == 52); // e_ehsize
assert(get_le16(loader + 42) == 32); // e_phentsize
assert(get_le16(loader + 44) == 2); // e_phnum
assert(get_le16(loader + 44) == 1); // e_phnum
assert(get_le16(loader + 48) == 0); // e_shnum
assert(lsize > 128 && lsize < 4096);
@@ -454,6 +457,32 @@ void PackLinuxI386::patchLoaderChecksum()
}
void PackLinuxI386::updateLoader(OutputFile *fo)
{
#define PAGE_MASK (~0<<12)
Elf_LE32_Ehdr *ehdr = (Elf_LE32_Ehdr *)(unsigned char *)loader;
ehdr->e_phnum = 2;
// The first Phdr maps the stub (instructions, data, bss) rwx.
// Round up hi address to page boundary.
Elf_LE32_Phdr *phdro = (Elf_LE32_Phdr *)(sizeof(Elf_LE32_Ehdr)+loader);
unsigned const vaddr2 = PAGE_MASK & (~PAGE_MASK + phdro->p_memsz + phdro->p_vaddr);
// The second Phdr maps the overlay r--,
// to defend against /usr/bin/strip removing the overlay.
++phdro;
phdro->p_type = PT_LOAD;
phdro->p_offset = lsize;
phdro->p_paddr = phdro->p_vaddr = vaddr2 + (lsize &~ PAGE_MASK);
phdro->p_memsz = phdro->p_filesz = fo->getBytesWritten() - lsize;
phdro->p_flags = PF_R;
phdro->p_align = -PAGE_MASK;
patchLoaderChecksum();
fo->seek(0, SEEK_SET);
fo->rewrite(loader, 0x80);
#undef PAGE_MASK
}
/*
vi:ts=4:et
*/