From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Date: Sat, 11 Feb 2012 17:31:46 +0400 From: Solar Designer Message-ID: <20120211133146.GA19489@openwall.com> References: <20120210020658.GA17709@dztty> <20120210143616.GA6100@albatros> <20120211092050.GA18669@openwall.com> <20120211102105.GA18464@albatros> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120211102105.GA18464@albatros> Subject: Re: [kernel-hardening] procfs: infoleaks and DAC permissions To: kernel-hardening@lists.openwall.com List-ID: On Sat, Feb 11, 2012 at 02:21:06PM +0400, Vasiliy Kulikov wrote: > On Sat, Feb 11, 2012 at 13:20 +0400, Solar Designer wrote: > > I did not look into this closely, but my current understanding is that > > apparently glibc reads the process' own proc files only, and restricting > > their perms to 0400 breaks this if the process changes euid/fsuid during > > its runtime. Right? > > Yes, AFAICS, it looks whether a specific memory area is RW. But looking > at "grep -r /proc/self/ glibc-sources/" output I can say /proc/self/maps > is not the only file usage which might be broken by open() restricting. Yes, and not all pathnames are constant - there's also "/proc/self/task/%u/comm". Alexander