[Dwarf-Discuss] security implications of DWARF info
David Anderson
davea42@earthlink.net
Wed Nov 24 22:56:55 GMT 2010
On 11/24/2010 07:34 AM, James Oakley wrote:
> You and I disagree about security through obscurity, but this list is
> not the place for that discussion.
>
> > However, I'm not familiar with libraries for
> > writing/generating/modifying DWARF files. I checked the FAQ today;
> > the entries are empty.
>
> libdwarf (http://reality.sgiweb.org/davea/dwarf.html) is a library for
> reading and modifying DWARF information. There's outdated
> documentation for the consumer part of the library at
> ftp://ftp.software.ibm.com/software/os390/czos/dwarf/libdwarf2.1.pdf.
> There's a pdf with some documentation about the producer part of the
> library somewhere as well, but I can't find the link at the moment.
> There may be better/more current documentation.
>
The latest libdwarf/dwarfdump source distribution always has the latest
doc, in .mm and .pdf forms.
Libdwarf is not a library like typical DOM xml access libraries. DOM
access typically allows
reading xml into a tree in memory and modifying the tree in-situ and
writing it back out.
Libdwarf was conceived (in ~1991) as a tool for compiler-writers and
debuggers (as separate tasks). So the consumer
and producer code are totally separate headers and functions (but
packaged in
one archive or shared-library). It is not easy to unify the
consumer/producer tasks
as libdwarf is written. There is the beginnings of a read/write tool
(dwarfgen) in recent libdwarf releases,
but it is just a beginning, a hint.
The only other read/write tool using libdwarf that I recall seeing is
dwarfextract. It's
intended to gather the type data from numerous kernel .o files and
condense it into a single .o
with no type duplications (Written by Cliff Wickman when we were both
at SGI, open sourced
by SGI in 2005).
A version of dwarfextract is in the testsuite release (on same dwarf.h
web page, but separate
from libdwarf/dwarfdump).
David Anderson
--
Thank God men cannot as yet fly and lay waste the sky as well as the earth! -- Henry David Thoreau
More information about the Dwarf-discuss
mailing list