Frustrated with capabilities..
From: Markku Savela
Date: Wed Aug 27 2008 - 05:31:34 EST
I just want to run an exectable with limited capabilities and assumed
the following approach would work fine:
1) fork process
2) in child
2.1 set current capabilities (eip) using cap_set_proc
2.2 execve the executable.
But it frigging does not work! Just before the execve, the result of
cap_to_text is
= cap_net_bind_service+eip
but, in the execve executable, the result is suddenly
= cap_net_bind_service+i
Why does the execve clear the effective and permitted capabities,
against my clear instructions? (I also have the prctl KEEP_CAPS set,
though in this case it should be irrelevant).
- The kernel is from ubuntu distro, 2.6.24.
- the executable *does* *not* have any setuid/setgid bits
- the upcoming file capabities will not be any help, because I will
need to start the same executable with different capabilities
depending on context.
If this is not a bug in kernel, it is a misdesign, which makes the
obvious use of cap_set_proc rather useless...
--
Markku Savela
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/