Re: [1/1][PATCH] nproc v2: netlink access to /proc information

Chris Wright
2004-09-14T19:13:14Z

* Roger Luethi (rl@hellgate.ch) wrote:
> On Tue, 14 Sep 2004 11:37:36 -0700, Chris Wright wrote:
> > Canonical example is access(2) followed by open(2), not really relevant
> > in this case. However, exec setuid root app...when do you check, and
> > when to you fill in data to send back to user? For /proc, this type of
> > check happens often (see things like may_ptrace_attach and
> > task_dumpable in fs/proc/base.c).
>
> For nproc, the procedure looks like this: A tool send(2)s a request,
> credentials are attached to skb. Based on said credentials, the kernel
> is free to provide (netlink_unicast to originating socket) or withhold
> information. In this regard, nproc works like other netlink interfaces.

Understood. Question is, if the request is for data that's associated
with a task that is in the middle of an execve(setuid_root_app), does
the credential-check/skb-fill for response happen atomically w.r.t. said
execve? IOW, is it possible to pass credential check, then fill data
that's become sensitive since the check happened?

thanks,
-chris
--
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