linux-kernel - Re: [RFC][PATCH 8/8] check files for checkpointability

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090302095917.6cfeda55@thinkcentre.lan>
Date:	Mon, 2 Mar 2009 09:59:17 -0600
From:	Nathan Lynch <ntl@...ox.com>
To:	"Serge E. Hallyn" <serue@...ibm.com>
Cc:	Dave Hansen <dave@...ux.vnet.ibm.com>,
	containers <containers@...ts.linux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	hch@...radead.org, Ingo Molnar <mingo@...e.hu>,
	Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [RFC][PATCH 8/8] check files for checkpointability

On Mon, 2 Mar 2009 07:37:54 -0600
"Serge E. Hallyn" <serue@...ibm.com> wrote:

> Quoting Dave Hansen (dave@...ux.vnet.ibm.com):
> > 
> > Introduce a files_struct counter to indicate whether a particular
> > file_struct has ever contained a file which can not be
> > checkpointed.  This flag is a one-way trip; once it is set, it may
> > not be unset.
> > 
> > We assume at allocation that a new files_struct is clean and may
> > be checkpointed.  However, as soon as it has had its files filled
> > from its parent's, we check it for real in __scan_files_for_cr().
> > At that point, we mark it if it contained any uncheckpointable
> > files.
> > 
> > We also check each 'struct file' when it is installed in a fd
> > slot.  This way, if anyone open()s or managed to dup() an
> > unsuppored file, we can catch it.
> > 
> > Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com>
> 
> So on a practical note, Ingo's scheme appears to be paying off.  In
> order for any program's files_struct to be checkpointable right now,
> it must be statically compiled, else ld.so (I assume) looks up
> /proc/$$/status.  So since proc is not checkpointable, the result
> is irreversibly non-checkpointable.
> 
> So...  does it make sense to mark proc as checkpointable?  Do we
> reasonably assume that the same procfile will be available at
> restart?

With respect to /proc/$x/* where $x is the pid the restarted task wants,
is that not a chicken-and-egg problem?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/