【问题标题】:Putting each section into its own segment将每个部分放入自己的部分
【发布时间】:2019-11-03 12:06:29
【问题描述】:

我正在研究与地址空间布局随机化相关的内容,并尝试将默认ld链接描述文件通常分组的各个部分放入自己的段中。

这是默认的ld 链接器脚本;特别是.data.rel.ro.* 部分,我希望每个部分都有自己的部分。这可能吗?如果不是在带有ld 的 Linux 上,是否可以在任何其他系统上使用?

/* Script for -pie -z combreloc -z now -z relro: position independent executable, combine & sort relocs */
/* Copyright (C) 2014-2018 Free Software Foundation, Inc.
   Copying and distribution of this script, with or without modification,
   are permitted in any medium without royalty provided the copyright
   notice and this notice are preserved.  */
OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64",
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OUTPUT_ARCH(i386:x86-64)
ENTRY(_start)
SEARCH_DIR("=/usr/local/lib/x86_64-linux-gnu"); SEARCH_DIR("=/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu64"); SEARCH_DIR("=/usr/local/lib64"); SEARCH_DIR("=/lib64"); SEARCH_DIR("=/usr/lib64"); SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib"); SEARCH_DIR("=/usr/lib"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib64"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib");
SECTIONS
{
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      *(.rela.data .rela.data.* .rela.gnu.linkonce.d.*)
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  .eh_frame       : ONLY_IF_RO { KEEP (*(.eh_frame)) *(.eh_frame.*) }
  .gcc_except_table   : ONLY_IF_RO { *(.gcc_except_table
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  .gnu_extab   : ONLY_IF_RO { *(.gnu_extab*) }
  /* These sections are generated by the Sun/Oracle C++ compiler.  */
  .exception_ranges   : ONLY_IF_RO { *(.exception_ranges
  .exception_ranges*) }
  /* Adjust the address for the data segment.  We want to adjust up to
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  /* Exception handling  */
  .eh_frame       : ONLY_IF_RW { KEEP (*(.eh_frame)) *(.eh_frame.*) }
  .gnu_extab      : ONLY_IF_RW { *(.gnu_extab) }
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  .exception_ranges   : ONLY_IF_RW { *(.exception_ranges .exception_ranges*) }
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  .tdata      : { *(.tdata .tdata.* .gnu.linkonce.td.*) }
  .tbss       : { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }
  .preinit_array     :
  {
    PROVIDE_HIDDEN (__preinit_array_start = .);
    KEEP (*(.preinit_array))
    PROVIDE_HIDDEN (__preinit_array_end = .);
  }
  .init_array     :
  {
    PROVIDE_HIDDEN (__init_array_start = .);
    KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
    KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
    PROVIDE_HIDDEN (__init_array_end = .);
  }
  .fini_array     :
  {
    PROVIDE_HIDDEN (__fini_array_start = .);
    KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
    KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
    PROVIDE_HIDDEN (__fini_array_end = .);
  }
  .ctors          :
  {
    /* gcc uses crtbegin.o to find the start of
       the constructors, so we make sure it is
       first.  Because this is a wildcard, it
       doesn't matter if the user does not
       actually link against crtbegin.o; the
       linker won't look for a file to match a
       wildcard.  The wildcard also means that it
       doesn't matter which directory crtbegin.o
       is in.  */
    KEEP (*crtbegin.o(.ctors))
    KEEP (*crtbegin?.o(.ctors))
    /* We don't want to include the .ctor section from
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       The .ctor section from the crtend file contains the
       end of ctors marker and it must be last */
    KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .ctors))
    KEEP (*(SORT(.ctors.*)))
    KEEP (*(.ctors))
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  .dtors          :
  {
    KEEP (*crtbegin.o(.dtors))
    KEEP (*crtbegin?.o(.dtors))
    KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
    KEEP (*(SORT(.dtors.*)))
    KEEP (*(.dtors))
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  .dynamic        : { *(.dynamic) }
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  . = DATA_SEGMENT_RELRO_END (0, .);
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    *(.data .data.* .gnu.linkonce.d.*)
    SORT(CONSTRUCTORS)
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   *(.bss .bss.* .gnu.linkonce.b.*)
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  .gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }
  /DISCARD/ : { *(.note.GNU-stack) *(.gnu_debuglink) *(.gnu.lto_*) }
}

【问题讨论】:

    标签: linker ld aslr


    【解决方案1】:

    您可以使用链接描述文件中的: 子句为输出节指定目标程序头:

    这不会显示在默认链接描述文件中,因为默认程序头是由不同的机制生成的。

    【讨论】:

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