Пример #1
0
 def __getitem__(self, name):
     hash = 5381
     for c in name:
         hash = hash * 33 + c & bitmask(32)
     
     word = hash // self.maskword_bits % self.header['maskwords']
     self.stream.seek(self.filter + word * self.maskword_size)
     word = struct_parse(self.Maskword, self.stream)
     mask = 1 << hash % self.maskword_bits
     mask |= 1 << (hash >> self.header['shift2']) % self.maskword_bits
     if ~word & mask:
         raise KeyError(name)
     
     self.stream.seek(self.buckets + hash % self.header['nbuckets'] * 4)
     bucket = struct_parse(self.Elf_word(None), self.stream)
     if not bucket:
         raise KeyError(name)
     
     while True:
         offset = self.values + (bucket - self.header['symndx']) * 4
         value = struct_parse(self.Elf_word(None), self.stream,
             stream_pos=offset)
         if value & ~1 == hash & ~1:
             sym = self.symtab[bucket]
             if sym.name == name:
                 return sym
         
         if value & 1:
             raise KeyError(name)
         bucket += 1
def parse_macro_section(elf, dwarf, section):
    header_struct = create_header_struct(elf, dwarf)

    section.stream.seek(section['sh_offset'])
    header = struct_parse(header_struct, section.stream)
    yield header

    entry_struct = create_entry_struct(elf, dwarf, header.flags)

    while section.stream.tell() - section['sh_offset'] < section['sh_size']:
        yield struct_parse(entry_struct, section.stream)
Пример #3
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 def line_program_for_CU(self, cu):
     top_DIE = cu.get_top_DIE()
     if 'DW_AT_stmt_list' in top_DIE.attributes:
         stm = self.linestream
         stm.seek(top_DIE.attributes['DW_AT_stmt_list'].value, 0)
         structs = self.structs
         len = struct_parse(structs.Dwarf_uint32(''), stm)
         pc = struct_parse(structs.Dwarf_target_addr(''), stm)
         return LineTableV1(stm, structs, len, pc)
     else:
         return None
Пример #4
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 def __iter__(self):
     for offset in range(self.buckets, self.values, 4):
         self.stream.seek(offset)
         bucket = struct_parse(self.Elf_word(None), self.stream)
         if not bucket:
             continue
         sym = self.symtab[bucket]
         while True:
             offset = self.values + (bucket - self.header['symndx']) * 4
             value = struct_parse(self.Elf_word(None), self.stream,
                 stream_pos=offset)
             yield self.symtab[bucket]
             if value & 1:
                 break
             bucket += 1
Пример #5
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 def __iter__(self):
     end = self.chain + self.header['nchain'] * 4
     for offset in range(self.buckets, end, 4):
         self.stream.seek(offset)
         sym = struct_parse(self.Elf_word(None), self.stream)
         if sym:
             yield self.symtab[sym]
Пример #6
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def compute_relocation(elffile, reloc, symtab):
    if reloc['r_info_sym'] >= symtab.num_symbols():
        raise ELFRelocationError(
            'Invalid symbol reference in relocation: index %s' %
            (reloc['r_info_sym']))
    sym_value = symtab.get_symbol(reloc['r_info_sym'])['st_value']

    reloc_type = reloc['r_info_type']
    recipe = None

    if elffile.get_machine_arch() == 'x86':
        if reloc.is_RELA():
            raise ELFRelocationError('Unexpected RELA relocation for x86: %s' %
                                     reloc)
        recipe = _RELOCATION_RECIPES_X86.get(reloc_type, None)
    elif elffile.get_machine_arch() == 'x64':
        if not reloc.is_RELA():
            raise ELFRelocationError('Unexpected REL relocation for x64: %s' %
                                     reloc)
        recipe = _RELOCATION_RECIPES_X64.get(reloc_type, None)
    elif elffile.get_machine_arch() == 'MIPS':
        if reloc.is_RELA():
            raise ELFRelocationError(
                'Unexpected RELA relocation for MIPS: %s' % reloc)
        recipe = _RELOCATION_RECIPES_MIPS.get(reloc_type, None)

    if recipe is None:
        raise ELFRelocationError('Unsupported relocation type: %s' %
                                 reloc_type)

    # So now we have everything we need to actually perform the relocation.
    # Let's get to it:

    # 0. Find out which struct we're going to be using to read this value
    #    from the stream and write it back.
    if recipe.bytesize == 4:
        value_struct = elffile.structs.Elf_word('')
    elif recipe.bytesize == 8:
        value_struct = elffile.structs.Elf_word64('')
    else:
        raise ELFRelocationError('Invalid bytesize %s for relocation' %
                                 recipe.bytesize)

    # 1. Read the value from the stream (with correct size and endianness)
    original_value = struct_parse(value_struct,
                                  elffile.stream,
                                  stream_pos=reloc['r_offset'])
    # 2. Apply the relocation to the value, acting according to the recipe
    relocated_value = recipe.calc_func(
        value=original_value,
        sym_value=sym_value,
        offset=reloc['r_offset'],
        addend=reloc['r_addend'] if recipe.has_addend else 0)

    # 3. Return reolcation as a tuple
    # Make sure the relocated value fits back by wrapping it around. This
    # looks like a problem, but it seems to be the way this is done in
    # binutils too.
    relocated_value = relocated_value % (2**(recipe.bytesize * 8))
    return (reloc['r_offset'], relocated_value)
Пример #7
0
    def _parse_call_site_entry(self, encoding):

        base_encoding = encoding & 0x0f
        modifier = encoding & 0xf0

        # header
        s = struct_parse(
            Struct(
                'CallSiteEntry',
                self._formats[base_encoding]('cs_start'),
                self._formats[base_encoding]('cs_len'),
                self._formats[base_encoding]('cs_lp'),
                self.entry_structs.Dwarf_uleb128('cs_action'),
            ), self.stream)

        cs_start = s['cs_start']
        cs_len = s['cs_len']
        cs_lp = s['cs_lp']
        cs_action = s['cs_action']

        if modifier == 0:
            pass
        else:
            raise NotImplementedError(
                "Unsupported modifier for CallSiteEntry: %#x." % modifier)

        return CallSiteEntry(cs_start, cs_len, cs_lp, cs_action)
Пример #8
0
    def parse_expr(self, expr):
        stm = BytesIO(bytelist2string(expr))
        parsed = []

        while True:
            # Get the next opcode from the stream. If nothing is left in the
            # stream, we're done.
            byte = stm.read(1)
            if len(byte) == 0:
                break

            # Decode the opcode and its name.
            op = ord(byte)
            op_name = DW_OP_opcode2name.get(op, 'OP:0x%x' % op)

            if op <= 4 or op == 0x80:
                args = [
                    struct_parse(self.structs.Dwarf_target_addr(''), stm),
                ]
            else:
                args = []

            parsed.append(DWARFExprOp(op=op, op_name=op_name, args=args))

        return parsed
Пример #9
0
    def __init__(self, stm, cu, di):
        self.cu = cu
        self.dwarfinfo = di
        self.stream = stm
        self.offset = stm.tell()
        self.attributes = OrderedDict()
        self.tag = None
        self.has_children = None
        self.abbrev_code = None
        self.size = 0
        # Null DIE terminator. It can be used to obtain offset range occupied
        # by this DIE including its whole subtree.
        self._terminator = None
        self._parent = None

        structs = self.dwarfinfo.structs
        self.size = struct_parse(structs.Dwarf_uint32(''), stm)
        if self.size < 8:
            self.tag = 'DW_TAG_padding'
            self.has_children = False
        else:
            tag_code = struct_parse(structs.Dwarf_uint16(''), stm)
            if tag_code not in TAG_reverse:
                raise ValueError("%d not a known tag" % (tag_code))
            self.tag = TAG_reverse[tag_code]
            while stm.tell() < self.offset + self.size:
                attr_offset = self.stream.tell()
                attr = struct_parse(structs.Dwarf_uint16(''), stm)
                form = FORM_reverse[attr & 0xf]
                attr >>= 4
                if attr in ATTR_reverse:
                    name = ATTR_reverse[attr]
                elif 0x200 <= attr <= 0x3ff:  #DW_AT_MIPS represented as 0x204???
                    name = 'DW_AT_user_0x%x' % attr
                else:
                    raise ValueError("%d not a known attribute" % (attr))

                raw_value = struct_parse(structs.Dwarf_dw_form[form], stm)
                value = raw_value

                self.attributes[name] = AttributeValue(name=name,
                                                       form=form,
                                                       value=value,
                                                       raw_value=raw_value,
                                                       offset=attr_offset)
            self.has_children = self.attributes[
                'DW_AT_sibling'].value >= self.offset + self.size + 8
Пример #10
0
    def _parse_lsda_header(self):

        # lpstart
        lpstart_encoding = self.stream.read(1)[0]
        if lpstart_encoding != DW_EH_encoding_flags['DW_EH_PE_omit']:
            base_encoding = lpstart_encoding & 0x0f
            modifier = lpstart_encoding & 0xf0

            lpstart = struct_parse(
                Struct('dummy', self._formats[base_encoding]('LPStart')),
                self.stream)['LPStart']

            if modifier == 0:
                pass
            elif modifier == DW_EH_encoding_flags['DW_EH_PE_pcrel']:
                lpstart += self.address + (self.stream.tell() -
                                           self.base_offset)
            else:
                raise NotImplementedError("Unsupported modifier %#x." %
                                          modifier)

        else:
            lpstart = None

        # ttype
        ttype_encoding = self.stream.read(1)[0]
        if ttype_encoding != DW_EH_encoding_flags['DW_EH_PE_omit']:
            ttype_offset = struct_parse(
                Struct('dummy', self.entry_structs.Dwarf_uleb128('TType')),
                self.stream)['TType']
        else:
            ttype_offset = None

        # call site table length
        cstable_encoding = self.stream.read(1)[0]
        cstable_length = struct_parse(
            Struct('dummy', self.entry_structs.Dwarf_uleb128('CSTable')),
            self.stream)['CSTable']

        return ExceptionTableHeader(
            lpstart,
            ttype_encoding,
            ttype_offset,
            cstable_encoding,
            cstable_length,
        )
Пример #11
0
 def __init__(self, elf, *pos, **kw):
     BaseHash.__init__(self, elf, *pos, **kw)
     self.Elf_word = elf.structs.Elf_word
     self.header = Struct('Hash table header',
         self.Elf_word('nbucket'), self.Elf_word('nchain'))
     self.header = struct_parse(self.header, self.stream)
     self.buckets = self.stream.tell()
     self.chain = self.buckets + self.header['nbucket'] * 4
Пример #12
0
 def _iter_verneed(self, offset):
     [num] = self.entries["DT_VERNEEDNUM"]
     Elf_Verneed = self.elf.structs.Elf_Verneed
     for _ in range(num):
         entry = struct_parse(Elf_Verneed, self.elf.stream, offset)
         aux_offset = offset + entry["vn_aux"]
         versions = self._file_versions(aux_offset, entry["vn_cnt"])
         yield (self.strtab[entry["vn_file"]], versions)
         offset += entry["vn_next"]
Пример #13
0
 def __getitem__(self, sym):
     """Get Symbol() object for given table index"""
     
     self.stream.seek(self.offset + sym * self.entsize)
     entry = struct_parse(self.Elf_Sym, self.stream)
     
     name = entry['st_name']
     if name:
         name = self.stringtable[name]
     else:
         name = None
     
     return Symbol(entry, name)
Пример #14
0
    def __parse_files_info(self, dwarf_info, structs, offset=0):
        files = {}

        lineprog_header = struct_parse(structs.Dwarf_lineprog_header,
                                       dwarf_info.debug_line_sec.stream,
                                       offset)
        for i, entry in enumerate(lineprog_header.file_entry):
            files[i + 1] = File(
                id=i + 1,
                name=entry.name,
                directory=lineprog_header.include_directory[entry.dir_index -
                                                            1])

        return files
Пример #15
0
 def get_entries(self):
     if self._decoded_entries is None:
         stm = self.stm
         offset = stm.tell()
         end_offset = offset + self.len
         structs = self.structs
         entries = []
         pc = self.pc
         while offset < end_offset:
             line = struct_parse(structs.Dwarf_uint32(''), stm)
             col = struct_parse(structs.Dwarf_uint16(''), stm)
             pc_delta = struct_parse(structs.Dwarf_uint32(''), stm)
             if line == 0:
                 break
             state = LineState(True)
             state.file = 0
             state.line = line
             state.column = col if col != 0xffff else None
             state.address = pc
             entries.append(LineProgramEntry(0, False, [], state))
             pc += pc_delta
         self._decoded_entries = entries
     return self._decoded_entries
Пример #16
0
 def version_definitions(self):
     offset = self.entries["DT_VERDEF"]
     if not offset:
         return
     [offset] = offset
     offset = self.segments.map(offset)
     [num] = self.entries["DT_VERDEFNUM"]
     Elf_Verdef = self.elf.structs.Elf_Verdef
     for _ in range(num):
         entry = struct_parse(Elf_Verdef, self.elf.stream, offset)
         aux_offset = offset + entry["vd_aux"]
         names = self._version_names(aux_offset, entry["vd_cnt"])
         definition = Version(entry, next(names))
         yield (definition, names)
         offset += entry["vd_next"]
Пример #17
0
 def __getitem__(self, name):
     hash = 0
     for c in name:
         hash = (hash << 4) + c
         hash = (hash ^ hash >> 24 & 0xF0) & bitmask(28)
     
     self.stream.seek(self.buckets + hash % self.header['nbucket'] * 4)
     while True:
         index = struct_parse(self.Elf_word(None), self.stream)
         if not index:
             raise KeyError(name)
         
         sym = self.symtab[index]
         if sym.name == name:
             return sym
         
         self.stream.seek(self.chain + index * 4)
Пример #18
0
 def __init__(self, elf, *pos, **kw):
     BaseHash.__init__(self, elf, *pos, **kw)
     self.Elf_word = elf.structs.Elf_word
     self.Maskword = elf.structs.Elf_xword("Maskword")
     self.header = Struct('GNU hash table header',
         self.Elf_word('nbuckets'),
         self.Elf_word('symndx'),
         self.Elf_word('maskwords'),
         self.Elf_word('shift2'),
     )
     self.header = struct_parse(self.header, self.stream)
     self.filter = self.stream.tell()
     self.maskword_size = self.Maskword.sizeof()
     self.maskword_bits = self.maskword_size * 8
     self.buckets = (self.filter +
         self.header['maskwords'] * self.maskword_size)
     self.values = self.buckets + self.header['nbuckets'] * 4
Пример #19
0
def iter_notes(self):
    """ Iterates the list of notes in the segment.
    """
    offset = self['p_offset']
    end = self['p_offset'] + self['p_filesz']
    while offset < end:
        note = struct_parse(self.elffile.structs.Elf_Nhdr,
                            self.stream,
                            stream_pos=offset)
        note['n_offset'] = offset
        offset += self.elffile.structs.Elf_Nhdr.sizeof()
        self.stream.seek(offset)
        # n_namesz is 4-byte aligned.
        disk_namesz = roundup(note['n_namesz'], 2)
        note['n_name'] = bytes2str(
            CString('').parse(self.stream.read(disk_namesz)))
        offset += disk_namesz

        desc_data = bytes2str(self.stream.read(note['n_descsz']))
        note['n_desc'] = desc_data
        offset += roundup(note['n_descsz'], 2)
        note['n_size'] = offset - note['n_offset']
        yield note
Пример #20
0
def iter_notes(self):
    """ Iterates the list of notes in the segment.
    """
    offset = self['p_offset']
    end = self['p_offset'] + self['p_filesz']
    while offset < end:
        note = struct_parse(
            self._elfstructs.Elf_Nhdr,
            self.stream,
            stream_pos=offset)
        note['n_offset'] = offset
        offset += self._elfstructs.Elf_Nhdr.sizeof()
        self.stream.seek(offset)
        # n_namesz is 4-byte aligned.
        disk_namesz = roundup(note['n_namesz'], 2)
        note['n_name'] = bytes2str(
            CString('').parse(self.stream.read(disk_namesz)))
        offset += disk_namesz

        desc_data = bytes2str(self.stream.read(note['n_descsz']))
        note['n_desc'] = desc_data
        offset += roundup(note['n_descsz'], 2)
        note['n_size'] = offset - note['n_offset']
        yield note
Пример #21
0
 def rel_table_entries(self, entries, size, type):
     (entsize, Struct) = {
         "DT_RELA": ("DT_RELAENT", self.elf.structs.Elf_Rela),
         "DT_REL": ("DT_RELENT", self.elf.structs.Elf_Rel),
     }[type]
     
     (table,) = entries
     (size,) = self.entries[size]
     (entsize,) = self.entries[entsize]
     table = self.segments.map(table, size)
     
     if entsize < Struct.sizeof():
         msg = "{} entry size too small: {}"
         raise NotImplementedError(msg.format(Struct.name, entsize))
     if size % entsize:
         msg = "{} table size: {}"
         raise NotImplementedError(msg.format(Struct.name, size))
     
     # TODO: mmap
     # TODO: read rel table in one go
     for offset in range(table, table + size, entsize):
         self.elf.stream.seek(offset)
         entry = struct_parse(Struct, self.elf.stream)
         yield Relocation(entry, self.elf)
Пример #22
0
    def _parse_lsda_header(self):
        # https://www.airs.com/blog/archives/464

        self.elf.seek(self.lsda_offset)

        lpstart_raw = self.elf.read(1)[0]
        lpstart = None
        if lpstart_raw != DW_EH_encoding_flags['DW_EH_PE_omit']:
            # See https://www.airs.com/blog/archives/460, it should be omit in
            # practice
            raise Exception("We do not handle this case for now")
            base_encoding = lpstart_raw & 0x0F
            modifier = lpstart_raw & 0xF0

            lpstart = struct_parse(
                Struct('dummy', self._formats[base_encoding]('LPStart')),
                self.elf)['LPStart']

            if modifier == 0:
                pass
            elif modifier == DW_EH_encoding_flags['DW_EH_PE_pcrel']:
                lpstart += self.address + (self.elf.tell() - self.base_offset)
            else:
                raise Exception("what")

        typetable_encoding = self.elf.read(1)[0]
        typetable_offset = None
        # NOW TODO : the encoding is the right one + 1, which is weird

        self.typetable_offset = 0

        if typetable_encoding != DW_EH_encoding_flags['DW_EH_PE_omit']:
            self.typetable_offset = struct_parse(
                Struct('dummy', self.entry_structs.Dwarf_uleb128('TType')),
                self.elf)['TType']
            self.typetable_offset_present = True
        else:
            self.typetable_offset_present = False

        call_site_table_encoding = self.elf.read(1)[0]
        call_site_table_len = struct_parse(
            Struct('dummy', self.entry_structs.Dwarf_uleb128('CSTable')),
            self.elf)['CSTable']

        if self.typetable_offset_present == False:
            self.typetable_offset = call_site_table_len

        print("lpstart", lpstart_raw)
        print("lpstart_pcrel", lpstart)
        print("typetable_encoding", typetable_encoding)
        print("call_site_table_encoding", call_site_table_encoding)

        print("CALL SITE TABLE LENGTH %d" % call_site_table_len)
        print("TYPETABLE OFFSET %d" % self.typetable_offset)

        self.end_label = ".LLSDATT%x" % self.fstart
        self.table_label = ".LLSDATTD%x" % self.fstart
        self.action_label = ".LLSDACSE%x" % self.fstart
        self.callsite_label = ".LLSDACSB%x" % self.fstart
        self.ttable_prefix_label = ".LLSDATYP%x" % self.fstart

        # Need to construct some representation here.
        self.header = {
            "lpstart": lpstart_raw,
            "encoding": call_site_table_encoding,
            "typetable_encoding": typetable_encoding,
            "call_site_table_len": call_site_table_len,
            "cs_act_tt_total_len": self.
            typetable_offset,  # Don't forget to check typetable_offset_present
        }
Пример #23
0
def ParseELFSymbols(elf):
  """Parses list of symbols in an ELF file.

  Args:
    elf: An elffile.ELFFile instance.

  Returns:
    A 2-tuple of (imported, exported) symbols. |imported| is a set of strings
    of undefined symbols. |exported| is a dict where the keys are defined
    symbols and the values are 3-tuples (st_info_bind, st_size, st_shndx) with
    the details of the corresponding exported symbol. Note that for imported
    symbols this information is always ('STB_GLOBAL', 0, 'SHN_UNDEF') and thus
    not included in the result.
  """
  imp = set()
  exp = dict()

  if elf.header.e_type not in ('ET_DYN', 'ET_EXEC'):
    return imp, exp

  for segment in elf.iter_segments():
    if segment.header.p_type != 'PT_DYNAMIC':
      continue

    # Find strtab and symtab virtual addresses.
    strtab_ptr = None
    symtab_ptr = None
    symbol_size = elf.structs.Elf_Sym.sizeof()
    for tag in segment.iter_tags():
      if tag.entry.d_tag == 'DT_SYMTAB':
        symtab_ptr = tag.entry.d_ptr
      if tag.entry.d_tag == 'DT_STRTAB':
        strtab_ptr = tag.entry.d_ptr
      if tag.entry.d_tag == 'DT_SYMENT':
        assert symbol_size == tag.entry.d_val

    stringtable = segment._get_stringtable()  # pylint: disable=W0212

    symtab_offset = next(elf.address_offsets(symtab_ptr))
    # Assume that symtab ends right before strtab.
    # This is the same assumption that glibc makes in dl-addr.c.
    # The first symbol is always local undefined, unnamed so we ignore it.
    for i in range(1, (strtab_ptr - symtab_ptr) / symbol_size):
      symbol_offset = symtab_offset + (i * symbol_size)
      symbol = utils.struct_parse(elf.structs.Elf_Sym, elf.stream,
                                  symbol_offset)
      if symbol['st_info']['bind'] == 'STB_LOCAL':
        # Ignore local symbols.
        continue
      symbol_name = stringtable.get_string(symbol.st_name)
      if symbol['st_shndx'] == 'SHN_UNDEF':
        if symbol['st_info']['bind'] == 'STB_GLOBAL':
          # Global undefined --> required symbols.
          # We ignore weak undefined symbols.
          imp.add(symbol_name)
      elif symbol['st_other']['visibility'] == 'STV_DEFAULT':
        # Exported symbols must have default visibility.
        st_shndx = SH_TYPE_VALUES.get(symbol['st_shndx'], symbol['st_shndx'])
        exp[symbol_name] = (symbol['st_info']['bind'], symbol['st_size'],
                            st_shndx)
  return imp, exp
Пример #24
0
def ParseELFSymbols(elf):
    """Parses list of symbols in an ELF file.

  Args:
    elf: An elffile.ELFFile instance.

  Returns:
    A 2-tuple of (imported, exported) symbols. |imported| is a set of strings
    of undefined symbols. |exported| is a dict where the keys are defined
    symbols and the values are 3-tuples (st_info_bind, st_size, st_shndx) with
    the details of the corresponding exported symbol. Note that for imported
    symbols this information is always ('STB_GLOBAL', 0, 'SHN_UNDEF') and thus
    not included in the result.
  """
    imp = set()
    exp = dict()

    if elf.header.e_type not in ('ET_DYN', 'ET_EXEC'):
        return imp, exp

    for segment in elf.iter_segments():
        if segment.header.p_type != 'PT_DYNAMIC':
            continue

        # Find strtab and symtab virtual addresses.
        strtab_ptr = None
        symtab_ptr = None
        symbol_size = elf.structs.Elf_Sym.sizeof()
        for tag in segment.iter_tags():
            if tag.entry.d_tag == 'DT_SYMTAB':
                symtab_ptr = tag.entry.d_ptr
            if tag.entry.d_tag == 'DT_STRTAB':
                strtab_ptr = tag.entry.d_ptr
            if tag.entry.d_tag == 'DT_SYMENT':
                assert symbol_size == tag.entry.d_val

        stringtable = segment._get_stringtable()  # pylint: disable=W0212

        symtab_offset = next(elf.address_offsets(symtab_ptr))
        # Assume that symtab ends right before strtab.
        # This is the same assumption that glibc makes in dl-addr.c.
        # The first symbol is always local undefined, unnamed so we ignore it.
        for i in range(1, (strtab_ptr - symtab_ptr) / symbol_size):
            symbol_offset = symtab_offset + (i * symbol_size)
            symbol = utils.struct_parse(elf.structs.Elf_Sym, elf.stream,
                                        symbol_offset)
            if symbol['st_info']['bind'] == 'STB_LOCAL':
                # Ignore local symbols.
                continue
            symbol_name = stringtable.get_string(symbol.st_name)
            if symbol['st_shndx'] == 'SHN_UNDEF':
                if symbol['st_info']['bind'] == 'STB_GLOBAL':
                    # Global undefined --> required symbols.
                    # We ignore weak undefined symbols.
                    imp.add(symbol_name)
            elif symbol['st_other']['visibility'] == 'STV_DEFAULT':
                # Exported symbols must have default visibility.
                st_shndx = SH_TYPE_VALUES.get(symbol['st_shndx'],
                                              symbol['st_shndx'])
                exp[symbol_name] = (symbol['st_info']['bind'],
                                    symbol['st_size'], st_shndx)
    return imp, exp
Пример #25
0
def ParseELFSymbols(elf):
  """Parses list of symbols in an ELF file.

  Args:
    elf: An elffile.ELFFile instance.

  Returns:
    A 2-tuple of (imported, exported) symbols, each of which is a set.
  """
  imp = set()
  exp = set()

  if elf.header.e_type not in ('ET_DYN', 'ET_EXEC'):
    return imp, exp

  for segment in elf.iter_segments():
    if segment.header.p_type != 'PT_DYNAMIC':
      continue

    # Find strtab and symtab virtual addresses.
    symtab_ptr = None
    dthash_ptr = None
    symbol_size = elf.structs.Elf_Sym.sizeof()
    for tag in segment.iter_tags():
      if tag.entry.d_tag == 'DT_SYMTAB':
        symtab_ptr = tag.entry.d_ptr
      if tag.entry.d_tag == 'DT_SYMENT':
        assert symbol_size == tag.entry.d_val
      if tag.entry.d_tag == 'DT_HASH':
        dthash_ptr = tag.entry.d_ptr

    stringtable = segment._get_stringtable()  # pylint: disable=protected-access

    symtab_offset = next(elf.address_offsets(symtab_ptr))

    if dthash_ptr:
      # DT_SYMTAB provides no information on the number of symbols table
      # entries. Instead, we use DT_HASH's nchain value, which according to the
      # spec, "should equal the number of symbol table entries".
      # nchain is the second 32-bit integer at the address pointed by DT_HASH,
      # both for ELF and ELF64 formats.
      fmt = '<I' if elf.little_endian else '>I'
      elf.stream.seek(dthash_ptr + 4)
      nsymbols = struct.unpack(fmt, elf.stream.read(4))[0]
    else:
      # Get the size of DYNSYM section from section header.
      symtab_size = int(GetSymbolTableSize(elf))
      nsymbols = symtab_size // symbol_size

    # The first symbol is always local undefined, unnamed so we ignore it.
    for i in range(1, nsymbols):
      symbol_offset = symtab_offset + (i * symbol_size)
      symbol = utils.struct_parse(elf.structs.Elf_Sym, elf.stream,
                                  symbol_offset)
      if symbol['st_info']['bind'] == 'STB_LOCAL':
        # Ignore local symbols.
        continue
      symbol_name = stringtable.get_string(symbol.st_name)
      if symbol['st_shndx'] == 'SHN_UNDEF':
        if symbol['st_info']['bind'] == 'STB_GLOBAL':
          # Global undefined --> required symbols.
          # We ignore weak undefined symbols.
          imp.add(symbol_name)
      elif symbol['st_other']['visibility'] == 'STV_DEFAULT':
        # Exported symbols must have default visibility.
        exp.add(symbol_name)

  return imp, exp
Пример #26
0
    def _parse_lsda_entries(self):
        start_cs_offset = self.elf.tell()

        action_count = 0

        while self.elf.tell(
        ) - start_cs_offset < self.header["call_site_table_len"]:
            base_encoding = self.header["encoding"] & 0x0f
            modifier = self.header["encoding"] & 0xf0

            # Maybe we need to store the offset in the entry ?

            # header
            s = struct_parse(
                Struct(
                    'CallSiteEntry',
                    self._formats[base_encoding]('cs_start'),
                    self._formats[base_encoding]('cs_len'),
                    self._formats[base_encoding]('cs_lp'),
                    self.entry_structs.Dwarf_uleb128('cs_action'),
                ), self.elf)

            cs_action = s['cs_action']
            if cs_action != 0:
                action_offset_bytes = (cs_action + 1) >> 1
                action_count = max(action_count, action_offset_bytes)

            self.entries.append(s)

        processed_bytes = self.elf.tell() - start_cs_offset
        print("+++++ %d bytes read, %d to go, %d actions" %
              (processed_bytes, self.typetable_offset - processed_bytes,
               action_count))

        idx = action_count
        processed_action_count = 0

        while idx > 0:

            action = struct_parse(
                Struct("ActionEntry",
                       self.entry_structs.Dwarf_uint8('act_filter'),
                       self.entry_structs.Dwarf_uint8('act_next')), self.elf)

            print(">>>> ACTION ", action)
            self.actions.append(action)
            processed_action_count = processed_action_count + 1
            idx -= 1

        ttendloc = self.lsda_offset + self.typetable_offset + 3

        print("TT %x" % (ttendloc))
        for action in self.actions:

            type_bytes_offset = (action.act_filter * -8)
            ttentryloc = ttendloc + type_bytes_offset
            print("****** TT LOC: %x" % (ttentryloc))
            self.elf.seek(ttentryloc, io.SEEK_SET)
            ptrbytes = self.elf.read(8)
            ptr = struct.unpack("<Q", ptrbytes)[0]
            print("****** TT PTR: %x" % ptr)

            symbolized_target = 0
            if ptr != 0:
                symbolized_target = ptr + ttentryloc

            typeentry = {'address': symbolized_target}
            self.ttentries[action.act_filter] = typeentry
            print("****** TT x: %x" % (symbolized_target))
Пример #27
0
 def _file_versions(self, offset, cnt):
     Elf_Vernaux = self.elf.structs.Elf_Vernaux
     for _ in range(cnt):
         entry = struct_parse(Elf_Vernaux, self.elf.stream, offset)
         yield VersionAuxiliary(entry, self.strtab[entry["vna_name"]])
         offset += entry["vna_next"]
Пример #28
0
 def _version_names(self, offset, cnt):
     Elf_Verdaux = self.elf.structs.Elf_Verdaux
     for _ in range(cnt):
         entry = struct_parse(Elf_Verdaux, self.elf.stream, offset)
         yield self.strtab[entry["vda_name"]]
         offset += entry["vda_next"]