Date: Mon, 14 Oct 2013 20:18:24 +1100 From: Ryan Mallon <rmallon@...il.com> To: "Eric W. Biederman" <ebiederm@...ssion.com> CC: George Spelvin <linux@...izon.com>, joe@...ches.com, akpm@...ux-foundation.org, dan.j.rosenberg@...il.com, eldad@...refinery.com, jgunthorpe@...idianresearch.com, jkosina@...e.cz, keescook@...omium.org, kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk, rusty@...tcorp.com.au, Greg Kroah-Hartman <gregkh@...uxfoundation.org> Subject: Re: [PATCH v3a] vsprintf: Check real user/group id for %pK On 12/10/13 09:37, Eric W. Biederman wrote: > Ryan Mallon <rmallon@...il.com> writes: > >> The only remaining problem is kernel/module.c:module_sect_show() which >> is used to write the sysfs files in /sys/module/<modname>/sections/. >> Those files are actually are really good target for leaking %pK values >> via setuid binaries. The problem is that the module_sect_show() function >> isn't passed information about who opened the sysfs file. I don't think >> this information is available in general for sysfs files either. Also, >> I can't actually see how module_sect_show() gets called? >> >> I'm a bit stuck on how to solve this. Any ideas? > > I haven't yet had a chance to review the patches but there are patches > to make sysfs files seq files in Greg's driver core tree. Hmm, I had a look at the driver-core tree, and although sysfs files internally use the seq_file interface, the sysfs show/store handlers do not get passed the struct seq_file, so doesn't appear possible to do the checks there. We could add a sysfs_ops->seq_show, but that feels clunky to have two different interfaces for handling sysfs files. Converting the whole tree to pass struct seq_file to the sysfs handlers would be painful :-/. I assume the reason the /sys/module/<modname>/sections/* cannot be made 0400 is that some user-space tools are expecting those files to be readable by unprivileged users? ~Ryan
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.