From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Date: Tue, 21 Feb 2012 17:25:58 +0100 From: Djalal Harouni Message-ID: <20120221162558.GA12919@dztty> References: <20120210020658.GA17709@dztty> <20120210143616.GA6100@albatros> <20120221145653.GA22597@openwall.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120221145653.GA22597@openwall.com> Subject: Re: [kernel-hardening] procfs: infoleaks and DAC permissions To: kernel-hardening@lists.openwall.com Cc: Brad Spengler , Solar Designer List-ID: On Tue, Feb 21, 2012 at 06:56:53PM +0400, Solar Designer wrote: > On Fri, Feb 10, 2012 at 06:36:17PM +0400, Vasiliy Kulikov wrote: > > [1] http://grsecurity.net/~spender/dev_patches/distros_should_sponsor_me_for_doing_their_jobs.patch > > In order to provide its security, this relies on atomic64_t actually > being 64-bit and on atomic64_inc_return() returning a 64-bit value - but > one or both of these requirements appear to be violated for some archs. > > In fact, per a quick grep it appears that atomic64_inc_return() exists > for a subset of the archs only. There is the GENERIC_ATOMIC64 config option that can be used to support atomic64_t. [...] > Should there be a different revision of the patch for mainline? Perhaps > it'd have to use a spinlock at least on archs lacking 64-bit atomics. I want to add that atomic64_t is already used in other places: xfs log functions, perf counters, netfilter conntrack modules... That generic solution is already using raw spinlocks, but with a static hashed array, which is perhaps not perfect for a machine with a lot of CPUs ? BTW I'm still trying to work on these issues, and the global exec_id from spender's patch is the best solution, since it can be used as a global counter to track objects related to process/mm... as noted by Vasiliy in his other email. Out of context: from the git commit history we can see that there have been lately a lot of changes to /proc//* logic which is related to this sort of vulns. I'm trying to summarize them before sending more patches, just to avoid new problems. Thanks. -- tixxdz http://opendz.org