p_vmlinx.cpp

UPX 源代码

        }
        fo->write(&hdr_info, sizeof(hdr_info)); fo_off += sizeof(hdr_info);
        ppc32_extra += sizeof(hdr_info);
        if (ph.u_len!=f_len) {
            set_be32(&hdr_info.sz_unc, f_ptr - (upx_bytep) ibuf);
            set_be32(&hdr_info.sz_cpr, f_len);
            fo->write(&hdr_info, 2*sizeof(unsigned)); fo_off += 2*sizeof(unsigned);
            ppc32_extra += 2*sizeof(unsigned);
        }

#if 0  /*{ Documentation: changes to arch/powerpc/boot/main.c */
struct b_info {
	unsigned sz_unc;
	unsigned sz_cpr;
	unsigned char b_method;
	unsigned char b_ftid;
	unsigned char b_cto8;
	unsigned char b_unused;
};
typedef int (*upx_f_unc)(  /* uncompress */
	unsigned char const *src, unsigned  src_len,
	unsigned char       *dst, unsigned *dst_len,
	int method
);
typedef int (*upx_f_unf)(  /* unfilter */
	unsigned char *buf,
	unsigned len,
	unsigned cto8,
	unsigned ftid
);

unsigned char const *upx_expand(  // return updated src [aligned, too]
	unsigned char const *src,
	unsigned char       *dst,
	unsigned *const dst_len,
	upx_f_unc const f_unc
)
{
	if (0==*dst_len) {
		*dst_len = ((struct b_info const *)src)->sz_unc;
	}
	upx_f_unf const f_unf = (upx_f_unf)(sizeof(int) + (char *)f_unc);
	unsigned total_len = 0;
	unsigned need = *dst_len;
	while (0 < need) {
		struct b_info const *const b_hdr = (struct b_info const *)src;
		src = (unsigned char const *)(1+ b_hdr);
		unsigned blk_len = b_hdr->sz_unc;
		int const rv = (*f_unc)(src, b_hdr->sz_cpr, dst, &blk_len, b_hdr->b_method);
		if (0!=rv) {
			printf("decompress error %d\n\r", rv);
			exit();
		}
		if (b_hdr->b_ftid) {
			(*f_unf)(dst, b_hdr->sz_unc, b_hdr->b_cto8, b_hdr->b_ftid);
		}
		src += b_hdr->sz_cpr;
		src += (3& -(int)src);  // 4-byte align
		dst += b_hdr->sz_unc;
		total_len += b_hdr->sz_unc;
		need -= b_hdr->sz_unc;
	}
	*dst_len = total_len;
	return src;
}

void prep_kernel(unsigned long a1, unsigned long a2)
{
	upx_f_unc f_unc = (upx_f_unc)0;

	vmlinuz.addr = (unsigned long)_vmlinux_start;
	vmlinuz.size = (unsigned long)(_vmlinux_end - _vmlinux_start);

	if (0x55505821 == *(unsigned *)vmlinuz.addr) {
		/* was compressed by upx */
		/* Uncompress elfheader */
		unsigned const *const fwa = (unsigned *)vmlinuz.addr;
		f_unc = (upx_f_unc)((char *)&fwa[2] + fwa[1]);
		unsigned dst_len = 0;
		unsigned char const *src = (unsigned char const *)&fwa[2];
		src = upx_expand(src, (unsigned char *)elfheader, &dst_len, f_unc);
		unsigned const src_len = src - (unsigned char const *)&fwa[0];
		vmlinuz.addr += src_len;
		vmlinuz.size -= src_len;
	} else {
		memcpy(elfheader, (const void *)vmlinuz.addr,
		       sizeof(elfheader));
	}
=====
	/* Eventually gunzip the kernel */
	if (f_unc) {
		/* was compressed by upx */
		printf("upx_expand (0x%lx <- 0x%lx:0x%0lx)...",
		       vmlinux.addr, vmlinuz.addr, vmlinuz.addr+vmlinuz.size);
		unsigned dst_len = vmlinux.size - elfoffset;
		upx_expand((unsigned char const *)vmlinuz.addr,
		           (unsigned char       *)vmlinux.addr, &dst_len, f_unc);
		printf("done 0x%lx bytes\n\r", len);
	} else {
		memmove((void *)vmlinux.addr,(void *)vmlinuz.addr,
			vmlinuz.size);
		/* Skip over the ELF header */
#ifdef DEBUG
		printf("... skipping 0x%lx bytes of ELF header\n\r",
				elfoffset);
#endif
		vmlinux.addr += elfoffset;
	}
=====
}
#endif  /*}*/

    }
    else {
        compressWithFilters(&ft, 512, &cconf, getStrategy(ft));
    }
    unsigned const txt_c_len = ph.c_len;

    const unsigned lsize = getLoaderSize();

    defineDecompressorSymbols();
    defineFilterSymbols(&ft);
    relocateLoader();

    MemBuffer loader(lsize);
    memcpy(loader, getLoader(), lsize);
    patchPackHeader(loader, lsize);

#define shstrtab local_shstrtab // avoid -Wshadow warning
    char const shstrtab[]= "\0.text\0.note\0.shstrtab\0.symtab\0.strtab";
    char const *p = shstrtab;
    while (0!=*p++) ;
    shdro[1].sh_name = ptr_diff(p, shstrtab);
    shdro[1].sh_type = Shdr::SHT_PROGBITS;
    shdro[1].sh_flags = Shdr::SHF_ALLOC | Shdr::SHF_EXECINSTR;
    shdro[1].sh_offset = fo_off - ppc32_extra;
    shdro[1].sh_size = ppc32_extra + txt_c_len + lsize;  // plus more ...
    shdro[1].sh_addralign = 1;  // default

    fo_off += write_vmlinux_head(fo, &shdro[1]);
    fo->write(obuf, txt_c_len); fo_off += txt_c_len;
    unsigned const a = (shdro[1].sh_addralign -1) & (0u-(ppc32_extra + txt_c_len));
    if (0!=a) { // align
        fo_off += a;
        shdro[1].sh_size += a;
        fo->seek(a, SEEK_CUR);
    }
    fo->write(loader, lsize); fo_off += lsize;

#if 0
    printf("%-13s: compressed   : %8u bytes\n", getName(), txt_c_len);
    printf("%-13s: decompressor : %8u bytes\n", getName(), lsize);
#endif
    verifyOverlappingDecompression();

    // .note with 1st page --------------------------------
    ph.u_len = phdri[0].p_offset;
    fi->seek(0, SEEK_SET);
    fi->readx(ibuf, ph.u_len);
    compress(ibuf, ph.u_len, obuf, &cconf);

    while (0!=*p++) ;
    shdro[2].sh_name = ptr_diff(p, shstrtab);
    shdro[2].sh_type = Shdr::SHT_NOTE;
    shdro[2].sh_offset = fo_off;
    shdro[2].sh_size = sizeof(ph.u_len) + ph.c_len;
    shdro[2].sh_addralign = 1;
    tmp_u32 = ph.u_len; fo->write(&tmp_u32, 4);
    fo->write(obuf, ph.c_len); fo_off += shdro[2].sh_size;

    // .note with rest     --------------------------------
    ph.u_len = file_size - (sz_ptload + phdri[0].p_offset);
    fi->seek(sz_ptload + phdri[0].p_offset, SEEK_SET);
    fi->readx(ibuf, ph.u_len);

    // Temporarily decrease ph.level by about (1+ log2(sz_rest / sz_ptload))
    // to avoid spending unreasonable effort compressing large symbol tables
    // that are discarded 99.9% of the time anyway.
    int const old_level = ph.level;
    for (unsigned v = ((ph.u_len>>3) + ph.u_len) / sz_ptload; 0 < v; v>>=1) {
        if (0== --ph.level) {
            ph.level = 1;
        }
    }
    compress(ibuf, ph.u_len, obuf, &cconf);
    ph.level = old_level;

    // while (0!=*p++) ;  // name is the same
    shdro[3].sh_name = ptr_diff(p, shstrtab);
    shdro[3].sh_type = Shdr::SHT_NOTE;
    shdro[3].sh_offset = fo_off;
    shdro[3].sh_size = sizeof(ph.u_len) + ph.c_len;
    shdro[3].sh_addralign = 1;
    tmp_u32 = ph.u_len; fo->write(&tmp_u32, 4);
    fo->write(obuf, ph.c_len); fo_off += shdro[3].sh_size;

    while (0!=*p++) ;
    shdro[4].sh_name = ptr_diff(p, shstrtab);
    shdro[4].sh_type = Shdr::SHT_STRTAB;
    shdro[4].sh_offset = fo_off;
    shdro[4].sh_size = sizeof(shstrtab);  // already includes terminating '\0'
    shdro[4].sh_addralign = 1;
    fo->write(shstrtab, shdro[4].sh_size); fo_off += shdro[4].sh_size;

    fo_off = ~3 & (3+ fo_off); fo->seek(fo_off, SEEK_SET);
    while (0!=*p++) ;
    shdro[5].sh_name = ptr_diff(p, shstrtab);
    shdro[5].sh_type = Shdr::SHT_SYMTAB;
    shdro[5].sh_offset = fo_off;
    shdro[5].sh_size = ((Ehdr::EM_PPC==my_e_machine) + 5)*sizeof(Sym);
    //shdro[5].sh_flags = Shdr::SHF_INFO_LINK;
    shdro[5].sh_link = 6;  // to .strtab for symbols
    shdro[5].sh_info = 1+3;  // number of non-global symbols [binutils/bfd/elf.c]
    shdro[5].sh_addralign = 4;
    shdro[5].sh_entsize = sizeof(Sym);

    Sym sec_sym;

    // Symbol 0; no references, but bfd demands it.
    memset(&sec_sym, 0, sizeof(sec_sym));
    fo->write(&sec_sym, sizeof(sec_sym)); fo_off += sizeof(sec_sym);

    // Each section before .shstrtab needs a symbol.
    sec_sym.st_info = sec_sym.make_st_info(Sym::STB_LOCAL, Sym::STT_SECTION);
    sec_sym.st_other = Sym::STV_DEFAULT;
    sec_sym.st_shndx = 1;  // .text
    fo->write(&sec_sym, sizeof(sec_sym)); fo_off += sizeof(sec_sym);
    sec_sym.st_shndx = 2;  // .note
    fo->write(&sec_sym, sizeof(sec_sym)); fo_off += sizeof(sec_sym);
    sec_sym.st_shndx = 3;  // .note
    fo->write(&sec_sym, sizeof(sec_sym)); fo_off += sizeof(sec_sym);

    // the symbol we care about
    Sym unc_ker;
    unc_ker.st_name = 1;  // 1 byte into strtab
    unc_ker.st_value = 0;
    unc_ker.st_size = ppc32_extra + txt_c_len;
    unc_ker.st_info = unc_ker.make_st_info(Sym::STB_GLOBAL, Sym::STT_FUNC);
    unc_ker.st_other = Sym::STV_DEFAULT;
    unc_ker.st_shndx = 1;  // .text
    fo->write(&unc_ker, sizeof(unc_ker)); fo_off += sizeof(unc_ker);

    unsigned const lablen = strlen(my_boot_label);
    if (Ehdr::EM_PPC==my_e_machine) {
        unc_ker.st_name += 1+ lablen;
        unc_ker.st_value = unc_ker.st_size;
        unc_ker.st_size = 0;
        fo->write(&unc_ker, sizeof(unc_ker)); fo_off += sizeof(unc_ker);
    }
    while (0!=*p++) ;
    shdro[6].sh_name = ptr_diff(p, shstrtab);
    shdro[6].sh_type = Shdr::SHT_STRTAB;
    shdro[6].sh_offset = fo_off;
    shdro[6].sh_size = 2+ lablen + (Ehdr::EM_PPC==my_e_machine)*(1+ 12);  // '\0' before and after
    shdro[6].sh_addralign = 1;
    fo->seek(1, SEEK_CUR);  // the '\0' before
    fo->write(my_boot_label, 1+ lablen);  // include the '\0' terminator
    if (Ehdr::EM_PPC==my_e_machine) {
        fo->write("_vmlinux_end", 1+ 12); fo_off += 1+ 12;
    }
    fo_off += 2+ lablen;

    fo->seek(0, SEEK_SET);
    fo->write(&ehdro, sizeof(ehdro));
    fo->write(&shdro, sizeof(shdro));
    if (Ehdr::EM_PPC==my_e_machine) {
        fo->seek(sizeof(unsigned), SEEK_CUR);
        set_be32(&ppc32_extra, ppc32_extra - 2*sizeof(unsigned) + txt_c_len);
        fo->write(&ppc32_extra, sizeof(ppc32_extra));
    }

    if (!checkFinalCompressionRatio(fo))
        throwNotCompressible();
#undef shstrtab
}

template <class T>
int PackVmlinuxBase<T>::canUnpack()
{
    fi->seek(0, SEEK_SET);
    fi->readx(&ehdri, sizeof(ehdri));

    // now check the ELF header
    if (memcmp(&ehdri, "\x7f\x45\x4c\x46", 4)
    ||  ehdri.e_ident[Ehdr::EI_CLASS] != my_elfclass
    ||  ehdri.e_ident[Ehdr::EI_DATA] != my_elfdata
    ||  ehdri.e_ident[Ehdr::EI_VERSION] != Ehdr::EV_CURRENT
    ||  !memcmp(&ehdri.e_ident[8], "FreeBSD", 7)  // branded
    ||  ehdri.e_machine != my_e_machine
    ||  ehdri.e_version != 1  // version
    ||  ehdri.e_ehsize != sizeof(ehdri)  // different <elf.h> ?
    )
        return false;

    if (ehdri.e_type != Ehdr::ET_REL
    //i386 fails  ||  ehdri.e_shoff != sizeof(ehdri)  // Shdr not contiguous with Ehdr
    ||  ehdri.e_shentsize!=sizeof(Shdr)
    ||  ehdri.e_shnum < 4
    ||  (unsigned)file_size < (ehdri.e_shnum * sizeof(Shdr) + ehdri.e_shoff)
    )
        return false;

    // find the .shstrtab section
    Shdr const *const shstrsec = getElfSections();
    if (0==shstrsec) {
        return false;
    }

    // check for .text .note .note  and sane (.sh_size + .sh_offset)
    p_note0 = p_note1 = p_text = 0;
    int j;
    Shdr *p;
    for (p= shdri, j= ehdri.e_shnum; --j>=0; ++p) {
        if ((unsigned)file_size < (p->sh_size + p->sh_offset)
        ||  shstrsec->sh_size < (5+ p->sh_name) ) {
            continue;
        }
        if (0==strcmp(".text", shstrtab + p->sh_name)) {
            p_text = p;
        }
        if (0==strcmp(".note", shstrtab + p->sh_name)) {
            if (0==p_note0) {
                p_note0 = p;
            } else
            if (0==p_note1) {
                p_note1 = p;
            }
        }
    }
    if (0==p_text || 0==p_note0 || 0==p_note1) {
        return false;
    }

    char buf[1024];
    fi->seek(p_text->sh_offset + p_text->sh_size - sizeof(buf), SEEK_SET);
    fi->readx(buf, sizeof(buf));
    if (!getPackHeader(buf, sizeof(buf)))
        return -1; // format is known, but definitely is not packed

    return true;
}

template <class T>
void PackVmlinuxBase<T>::unpack(OutputFile *fo)
{
    U32 word;
    PackHeader const ph_tmp(ph);

    fi->seek(p_note0->sh_offset, SEEK_SET);
    fi->readx(&word, sizeof(word));
    ph.u_len = word;
    ph.c_len = p_note0->sh_size - sizeof(word);
    ibuf.alloc(ph.c_len);
    fi->readx(ibuf, ph.c_len);
    obuf.allocForUncompression(ph.u_len);
    decompress(ibuf, obuf, false);
    fo->write(obuf, ph.u_len);
    obuf.dealloc();
    ibuf.dealloc();

    ph = ph_tmp;
    if (!has_valid_vmlinux_head()) {
        throwCantUnpack(".text corrupted");
    }
    ibuf.alloc(ph.c_len);
    fi->readx(ibuf, ph.c_len);