[Ltrace-devel] PIE support
Petr Machata
pmachata at redhat.com
Mon Nov 27 20:31:47 CET 2006
Ian Wienand wrote:
> On Fri, Nov 24, 2006 at 05:02:45PM +0100, Petr Machata wrote:
>> I've written a PIE (position independent executables) support for
>> ltrace.
>
> Thanks! Is this from Redhat shipping this and stack randomisation by
> default for security?
No idea if there are plans to PIE everything. But certain network
related and security sensitive apps are, and it sucks when ltrace can't
handle them.
> I'm having a play, and I wonder if I'm seeing what you're seeing.
> On x86, for example, I don't see it picking up the puts call for a
Hmm, interesting. Moreso that __libc_start_main gets picked. I'll try
to reproduce that.
> ianw at jj:/tmp$ gcc -pie -o pie pie.c
^^^ could you try to compile with `gcc -fpie -pie -o pie pie.c`? Might
be that...
> printf? And on ia64 it doesn't seem to pick anything up at all, and
> breaks the testsuite (I haven't quite figured out why yet -- can
Aha, that's not very surprising. I dind't touch ia64 yet. It's on my
todo though.
> anyone give some pointers for running individual parts of the test
> suite and seeing what it is doing?)
E.g. `runtest ltrace.main/something.exp` will run a test for you, if
that is what you ask :) But apart from attach stuff, which is really
irritating to set up, almost everything is pretty simple to test
directly on prepared binaries.
>
> -i
>
> ---- ia64 ----
>
> ianw at lime:~/programs/ltrace/ltrace/trunk$ ./ltrace /tmp/pie
> pie
> +++ exited (status 4) +++
This probably means breakpoints end up in some insane place. That's how
ltrace acted on all pie binaries before. I'll look inside.
PM
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