p_exe.cpp

UPX 源代码

/* p_exe.cpp --

   This file is part of the UPX executable compressor.

   Copyright (C) 1996-2007 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996-2007 Laszlo Molnar
   All Rights Reserved.

   UPX and the UCL library are free software; you can redistribute them
   and/or modify them under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer   Laszlo Molnar
   [e-mail]      [e-mail]
 */


#include "conf.h"
#include "file.h"
#include "filter.h"
#include "packer.h"
#include "p_exe.h"
#include "linker.h"

static const
#include "stub/i086-dos16.exe.h"

#define RSFCRI          4096    // Reserved Space For Compressed Relocation Info
#define MAXMATCH        0x2000
#define MAXRELOCS       (0x8000-MAXMATCH)

#define DI_LIMIT        0xff00  // see the assembly why


/*************************************************************************
//
**************************************************************************/

PackExe::PackExe(InputFile *f) :
    super(f)
{
    bele = &N_BELE_RTP::le_policy;
    COMPILE_TIME_ASSERT(sizeof(exe_header_t) == 32);
    ih_exesize = ih_imagesize = ih_overlay = 0;
    stack_for_lzma = 0;
    use_clear_dirty_stack = false;

    // disable lzma for "--brute" unless explicitly given "--lzma"
    if (opt->all_methods_use_lzma && !opt->method_lzma_seen)
        opt->all_methods_use_lzma = false;
}


const int *PackExe::getCompressionMethods(int method, int level) const
{
    bool small = ih_imagesize <= 256*1024;
    return Packer::getDefaultCompressionMethods_8(method, level, small);
}


const int *PackExe::getFilters() const
{
    return NULL;
}


int PackExe::fillExeHeader(struct exe_header_t *eh) const
{
#define oh  (*eh)
    // fill new exe header
    int flag = 0;
    if (!opt->dos_exe.no_reloc && !M_IS_LZMA(ph.method))
        flag |= USEJUMP;
    if (ih.relocs == 0)
        flag |= NORELOC;

    memset(&oh,0,sizeof(oh));
    oh.ident = 'M' + 'Z' * 256;
    oh.headsize16 = 2;

    unsigned minsp = 0x200;
    if (M_IS_LZMA(ph.method))
        minsp = stack_for_lzma;
    minsp = ALIGN_UP(minsp, 16u);
    assert(minsp < 0xff00);
    if (oh.sp > minsp)
        minsp = oh.sp;
    if (minsp < 0xff00 - 2)
        minsp = ALIGN_UP(minsp, 2u);
    oh.sp = minsp;

    unsigned destpara = (ph.u_len + ph.overlap_overhead - ph.c_len + 31) / 16;
    oh.ss = ph.c_len/16 + destpara;
    if (ih.ss*16 + ih.sp < 0x100000 && ih.ss > oh.ss && ih.sp > 0x200)
        oh.ss = ih.ss;
    if (oh.ss*16 + 0x50 < ih.ss*16 + ih.sp
        && oh.ss*16 + 0x200 > ih.ss*16 + ih.sp)
        oh.ss += 0x20;

    if (oh.ss != ih.ss)
        flag |= SS;
    if (oh.sp != ih.sp || M_IS_LZMA(ph.method))
        flag |= SP;
    return flag;
#undef oh
}

void PackExe::addLoaderEpilogue(int flag)
{
    addLoader("EXEMAIN5", NULL);
    if (relocsize)
        addLoader(ph.u_len <= DI_LIMIT || (ph.u_len & 0x7fff) >= relocsize ? "EXENOADJ" : "EXEADJUS",
                  "EXERELO1",
                  has_9a ? "EXEREL9A" : "",
                  "EXERELO2",
                  ih_exesize > 0xFE00 ? "EXEREBIG" : "",
                  "EXERELO3",
                  NULL
                 );
    addLoader("EXEMAIN8",
              device_driver ? "DEVICEEND" : "",
              (flag & SS) ? "EXESTACK" : "",
              (flag & SP) ? "EXESTASP" : "",
              (flag & USEJUMP) ? "EXEJUMPF" : "",
              NULL
             );
    if (!(flag & USEJUMP))
        addLoader(ih.cs ? "EXERCSPO" : "",
                  "EXERETIP",
                  NULL
                 );

    linker->defineSymbol("original_cs", ih.cs);
    linker->defineSymbol("original_ip", ih.ip);
    linker->defineSymbol("original_sp", ih.sp);
    linker->defineSymbol("original_ss", ih.ss);
    linker->defineSymbol("reloc_size",
                         (ph.u_len <= DI_LIMIT || (ph.u_len & 0x7fff)
                          >= relocsize ? 0 : MAXRELOCS) - relocsize);
}

void PackExe::buildLoader(const Filter *)
{
    // get flag
    exe_header_t dummy_oh;
    int flag = fillExeHeader(&dummy_oh);

    initLoader(stub_i086_dos16_exe, sizeof(stub_i086_dos16_exe));

    if (M_IS_LZMA(ph.method))
    {
        addLoader("LZMA_DEC00",
                  opt->small ? "LZMA_DEC10" : "LZMA_DEC20",
                  "LZMA_DEC30",
                  use_clear_dirty_stack ? "LZMA_DEC31" : "",
                  "LZMA_DEC32",
                  ph.u_len > 0xffff ? "LZMA_DEC33" : "",
                  NULL
                 );

        addLoaderEpilogue(flag);
        defineDecompressorSymbols();
        const unsigned lsize0 = getLoaderSize();

        // Lzma decompression code starts at ss:0x10, and its size is
        // lsize bytes. It also needs getDecompressorWrkmemSize() bytes
        // during uncompression. It also uses some stack, so 0x100
        // more bytes are allocated
        stack_for_lzma = 0x10 + lsize0 + getDecompressorWrkmemSize() + 0x100;
        stack_for_lzma = ALIGN_UP(stack_for_lzma, 16u);

        unsigned clear_dirty_stack_low = 0x10 + lsize0;
        clear_dirty_stack_low = ALIGN_UP(clear_dirty_stack_low, 2u);
        if (use_clear_dirty_stack)
            linker->defineSymbol("clear_dirty_stack_low", clear_dirty_stack_low);

        relocateLoader();
        const unsigned lsize = getLoaderSize();
        assert(lsize0 == lsize);
        MemBuffer loader(lsize);
        memcpy(loader, getLoader(), lsize);

        MemBuffer compressed_lzma;
        compressed_lzma.allocForCompression(lsize);
        unsigned c_len_lzma = MemBuffer::getSizeForCompression(lsize);
        int r = upx_compress(loader, lsize, compressed_lzma, &c_len_lzma,
                             NULL, M_NRV2B_LE16, 9, NULL, NULL);
        assert(r == UPX_E_OK); assert(c_len_lzma < lsize);

        info("lzma+relocator code compressed: %u -> %u", lsize, c_len_lzma);
        // reinit the loader
        initLoader(stub_i086_dos16_exe, sizeof(stub_i086_dos16_exe));
        // prepare loader
        if (device_driver)
            addLoader("DEVICEENTRY,LZMADEVICE,DEVICEENTRY2", NULL);

        linker->addSection("COMPRESSED_LZMA", compressed_lzma, c_len_lzma, 0);
        addLoader("LZMAENTRY,NRV2B160,NRVDDONE,NRVDECO1,NRVGTD00,NRVDECO2",
                  NULL);

    }
    else if (device_driver)
        addLoader("DEVICEENTRY,DEVICEENTRY2", NULL);

    addLoader("EXEENTRY",
              M_IS_LZMA(ph.method) && device_driver ? "LONGSUB" : "SHORTSUB",
              "JNCDOCOPY",
              relocsize ? "EXERELPU" : "",
              "EXEMAIN4",
              M_IS_LZMA(ph.method) ? "" : "EXEMAIN4B",
              "EXEMAIN4C",
              M_IS_LZMA(ph.method) ? "COMPRESSED_LZMA_START,COMPRESSED_LZMA" : "",
              "+G5DXXXX,UPX1HEAD,EXECUTPO",
              NULL
             );
    if (ph.method == M_NRV2B_8)
        addLoader("NRV2B16S",               // decompressor
                  ph.u_len > DI_LIMIT ? "N2B64K01" : "",
                  "NRV2BEX1",
                  opt->cpu == opt->CPU_8086 ? "N2BX8601" : "N2B28601",
                  "NRV2BEX2",
                  opt->cpu == opt->CPU_8086 ? "N2BX8602" : "N2B28602",
                  "NRV2BEX3",
                  ph.c_len > 0xffff ? "N2B64K02" : "",
                  "NRV2BEX9",
                  NULL
                 );
    else if (ph.method == M_NRV2D_8)
        addLoader("NRV2D16S",
                  ph.u_len > DI_LIMIT ? "N2D64K01" : "",
                  "NRV2DEX1",
                  opt->cpu == opt->CPU_8086 ? "N2DX8601" : "N2D28601",
                  "NRV2DEX2",
                  opt->cpu == opt->CPU_8086 ? "N2DX8602" : "N2D28602",
                  "NRV2DEX3",
                  ph.c_len > 0xffff ? "N2D64K02" : "",
                  "NRV2DEX9",
                  NULL
                 );
    else if (ph.method == M_NRV2E_8)
        addLoader("NRV2E16S",
                  ph.u_len > DI_LIMIT ? "N2E64K01" : "",
                  "NRV2EEX1",
                  opt->cpu == opt->CPU_8086 ? "N2EX8601" : "N2E28601",
                  "NRV2EEX2",
                  opt->cpu == opt->CPU_8086 ? "N2EX8602" : "N2E28602",
                  "NRV2EEX3",
                  ph.c_len > 0xffff ? "N2E64K02" : "",
                  "NRV2EEX9",
                  NULL
                 );
    else if M_IS_LZMA(ph.method)
        return;
    else
        throwInternalError("unknown compression method");

    addLoaderEpilogue(flag);
}


/*************************************************************************
//
**************************************************************************/

int PackExe::readFileHeader()
{
    ih_exesize = ih_imagesize = ih_overlay = 0;
    fi->readx(&ih,sizeof(ih));
    if (ih.ident != 'M' + 'Z'*256 && ih.ident != 'Z' + 'M'*256)
        return 0;
    ih_exesize = ih.m512 + ih.p512*512 - (ih.m512 ? 512 : 0);
    ih_imagesize = ih_exesize - ih.headsize16*16;
    ih_overlay = file_size - ih_exesize;
    if (ih.m512+ih.p512*512u < sizeof (ih))
        throwCantPack("illegal exe header");
    if (file_size < (off_t)ih_exesize || ih_imagesize <= 0 || ih_imagesize > ih_exesize)
        throwCantPack("exe header corrupted");
#if 0
    printf("dos/exe header: %d %d %d\n", ih_exesize, ih_imagesize, ih_overlay);
#endif
    return UPX_F_DOS_EXE;
}


bool PackExe::canPack()
{
    if (fn_has_ext(fi->getName(),"sys"))
        return false;
    if (!readFileHeader())
        return false;
    if (file_size < 1024)
        throwCantPack("file is too small");
    fi->seek(0x3c,SEEK_SET);
    LE32 offs;
    fi->readx(&offs,sizeof (offs));
    if (ih.relocoffs >= 0x40 && offs)
    {
        if (opt->dos_exe.force_stub)
            opt->overlay = opt->COPY_OVERLAY;
        else
            throwCantPack("can't pack new-exe");
    }
    return true;
}


/*************************************************************************
//
**************************************************************************/

static
unsigned optimize_relocs(upx_byte *b, const unsigned size,
                         const upx_byte *relocs, const unsigned nrelocs,
                         upx_byte *crel, bool *has_9a)
{
    if (opt->exact)
        throwCantPackExact();

    upx_byte * const crel_save = crel;
    unsigned i;
    unsigned seg_high = 0;
#if 0
    unsigned seg_low = 0xffffffff;
    unsigned off_low = 0xffffffff;
    unsigned off_high = 0;
    unsigned linear_low = 0xffffffff;
    unsigned linear_high = 0;
#endif

    // pass 1 - find 0x9a bounds
    for (i = 0; i < nrelocs; i++)
    {
        unsigned addr = get_le32(relocs+4*i);
        if (addr >= size - 1)
            throwCantPack("unexpected relocation 1");
        if (addr >= 3 && b[addr-3] == 0x9a)
        {
            unsigned seg = get_le16(b+addr);
            if (seg > seg_high)
                seg_high = seg;
#if 0
            if (seg < seg_low)
                seg_low = seg;
            unsigned off = get_le16(b+addr-2);
            if (off < off_low)
                off_low = off;
            if (off > off_high)
                off_high = off;
            unsigned l = (seg << 4) + off;
            if (l < linear_low)
                linear_low = l;
            if (l > linear_high)
                linear_high = l;
#endif
        }
    }
    //printf("%d %d\n", seg_low, seg_high);
    //printf("%d %d\n", off_low, off_high);
    //printf("%d %d\n", linear_low, linear_high);


    // pass 2 - reloc

    crel += 4; // to be filled in later

    unsigned ones = 0;
    unsigned es = 0, di, t;
    i = 0;
    do
    {
        unsigned addr = get_le32(relocs+4*i);
        set_le16(crel,di = addr & 0x0f);
        set_le16(crel+2,(addr >> 4) - es);
        es = addr >> 4;
        crel += 4;

        for (++i; i < nrelocs; i++)
        {
            addr = get_le32(relocs+4*i);
            //printf ("%x\n",es*16+di);
            if ((addr - es*16 > 0xfffe)
                || (i == nrelocs - 1 && addr - es * 16 > 0xff00)
               )
            {
                // segment change
                t = 1+(0xffff-di)/254;
                memset(crel,1,t);
                crel += t;
                ones += t-1; // -1 is used to help the assembly stuff
                break;
            }
            unsigned offs = addr - es*16;
            if (offs >= 3 && b[es*16 + offs-3] == 0x9a && offs > di + 3)
            {
                for (t = di; t < offs-3; t++)
                    if (b[es*16+t] == 0x9a && get_le16(b+es*16+t+3) <= seg_high)
                        break;
                if (t == offs-3)
                {
                    // code 0: search for 0x9a
                    *crel++ = 0;
                    di = offs;
                    *has_9a = true;
                    continue;
                }
            }
            t = offs - di;
            if (t < 2)
                throwCantPack("unexpected relocation 2");

            while (t >= 256)
            {
                // code 1: add 254, don't reloc
                *crel++ = 1;
                t -= 254;
                ones++;
            }
            *crel++ = (unsigned char) t;
            di = offs;
        }
    } while (i < nrelocs);
    *crel++ = 1;
    ones++;
    set_le16 (crel_save,ones);
    set_le16 (crel_save+2,seg_high);

    //OutputFile::dump("x.rel", crel_save, crel - crel_save);
    return (unsigned) (crel - crel_save);