Question

ELF格式：

0x00~0x33是文件头
节标题和段标题必须是连续的

节条目可以存储在任何位置，按偏移量指定

所以我想把一个节条目（.dynsym）移到另一个位置，而且，仅适用于ELF32

实用程序下载链接： http://www10.zippyshare.com/v/25037401/file.html

The Process：
1. ModifyElf.exe
   I write a utility called ModifyElf.exe, it can move a section entry of elf file. Usage:
   ModifyElf.exe <srcfile> <dstfile> <sectionname> <mov2fileend:0|1> <clearold:0|1>
   args:
   <srcfile>         ->  src so file path
   <dstfile>         ->  dst so file path
   <sectionname>     ->  section name, just support ".dynsym " currently
   <mov2fileend:0|1> ->  mov2fileend:0 move section entry to the unused zero zone of so file, don't increase file size
                         mov2fileend:1 move section entry to the end of so file，will increase file size
   <clearold:0|1>    ->  clearold:0 don't clear the original section entry
                         clearold:1 set all bytes of original section entry to 0xFF

   for example：
   ModifyElf.exe e:\test\libfoo_ori.so e:\test\libfoo.so .dynsym mov2fileend:0 clearold:1

2. libfoo.so and linux_hello
   linux_hello call dlopen to load libfoo.so，and call myfn from libfoo.so, myfn just printf a string

   neil0@vm32:~/share/test$ sudo chmod a+x linux_hello 
   neil0@vm32:~/share/test$ export LD_LIBRARY_PATH=~/share/test:$LD_LIBRARY_PATH
   neil0@vm32:~/share/test$ ./linux_hello 
   dlopen ok!
   call myfn...!

3. modify and exec
   run ModifyElf.exe e:\test\libfoo_ori.so e:\test\libfoo.so .dynsym mov2fileend:0 clearold:1
   move section entry to zero zone, get a new so file, replace it in linux，and exec linux_hello, it's OK！You can use file compare tool to see diff between libfoo.so and libfoo_ori.so

   run ModifyElf.exe e:\test\libfoo_ori.so e:\test\libfoo.so .dynsym mov2fileend:1 clearold:1
   move section entry to file end，get a new so file, replace it in linux，and exec linux_hello, it's said "Segmentation fault"

所以你能告诉我为什么我不能把它移到文件结束，如果我想这样做我该怎么办？谢谢！

如何从精灵中移动部分条目？

0 个答案: