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https://github.com/wapiflapi/wsym
Adds symbols to a ELF file.
https://github.com/wapiflapi/wsym
Last synced: 2 months ago
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Adds symbols to a ELF file.
- Host: GitHub
- URL: https://github.com/wapiflapi/wsym
- Owner: wapiflapi
- License: mit
- Created: 2014-08-14T01:15:26.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2015-07-25T16:30:16.000Z (over 9 years ago)
- Last Synced: 2024-08-03T01:38:31.946Z (6 months ago)
- Language: Python
- Size: 179 KB
- Stars: 61
- Watchers: 7
- Forks: 10
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# wsym
Adds symbols to an ELF file. Sort of the opposite of strip.
This is in a very early stage of development and should
be considered PoC/beta software.
### why
I made this because I wanted gdb to know about the symbols I
defined in IDA when reverse engineering. I really think there
should be an easier way to do this but I couldn't find anything
that gdb understands except ELF, so yeah... overkill. Please
let me know if there is an easier way to tell gdb about
user defined symbols.
However this tool might be useful anyway since it is a more
generic solution.
### how to use
```
usage: wsym.py [-h] [-v] [-f SYMBOLS] [-i SYMBOLS] [-n SYMBOLS] input output
```
There are multiple ways to provide symbols that should be added
to the binary.
```-f, --flat```
> This is a very simple flat file format, one symbol per line:
>
> hex_addr name [hex_size]
```-i, --ida```
> Using this option you can provide a .map file generated by IDA.
>
> File > Produce File > Create MAP File -> segmentation & local
```-n, --nm```
> This is the output of nm, the flags outputted by nm
> to describe each symbol are ignored.
wsym will generate a new ELF file which can be directly run
under gdb, or you can use the add-symbol-file command in
order to load the symbols from the generated file while
debugging the original one.
**Warning:** running wsym repeatedly on a binary generated by itself
will keep increasing the file size and is probably a bad idea.
Always rerun on the original file.
### how this works
We recreate the section header table at the end of the file.
Adding original sections if there are any and re-adjusting
their sh_link and sh_info if needed.
We also add a GHOST section for each segment, this covers
the whole segment in case no other sections are present.
We create a new symtab called .wsymtab containing the provided
symbols. A new strtab for this symtab is added but we also
make a new shstrtab for all section names. This allows us to
touch the original file as little as possible.
### future work
- MORE TESTING: IIRC there is some weird stuff going on with
symtabs and entries need to be in a particular order for it
to work etc, etc... Maybe we should be nice and do this for
the user.
- Add a parser for another IDA output format in order to have sizes
- Allow for symbol types (data would be nice)
- Link a symbol to the smallest section containing said symbol
(instead of taking the first one that matches the address)