[vdr] -u in 1.3.38 -> no core dumps?

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Sun Jan 8 15:29:06 CET 2006


Ville Skyttä wrote:
> FYI: I had played with Ludwig Nussel's "su" patch in the past, and
> noticed that the setuid() stuff prevents VDR from dumping core in case
> of crashes.  I haven't really tested it yet, but from skimming the code
> it looks like the -u implementation included in 1.3.38 might have the
> same feature too.  Of course, no core dumps on crashes makes debugging
> problems a lot harder :(
> 
> Doing something like prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) after setuid()
> and setgid() should fix it, but there may be security implications to
> consider (whose implications in case of VDR are probably pretty small,
> but there's a reason why setuid/setgid things don't dump core by
> default...).  In kernels >= 2.6.13, "2" instead of "1" in the above
> would be available too, which would be quite a bit better.
> 
> Of course, the simplest "fix" for 1.3.38 would be to not even start it
> as root; no setuid/setgid -> no (new) problems getting core dumps.
> 
> More info: PR_SET_DUMPABLE in "man prctl", and
> http://lwn.net/Articles/104341/ (I'm not sure if that has been applied;
> mabe it has in >= 2.6.13).
> 
> Apologies beforehand if the above doesn't apply to VDR 1.3.38; as said,
> I haven't actually tested it but thought I'd report it while I remember.

I'm not going to dig into this myself, so if anybody would like
to propose a patch, please send it.

Klaus



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