[PATCH 0/6] File Sealing & memfd_create()

[Florian Weimer]

On 04/10/2014 10:37 PM, Andy Lutomirski wrote:

> It occurs to me that, before going nuts with these kinds of flags, it
> may pay to just try to fix the /proc/self/fd issue for real -- we
> could just make open("/proc/self/fd/3", O_RDWR) fail if fd 3 is
> read-only.  That may be enough for the file sealing thing.

Increasing privilege on O_PATH descriptors via access through 
/proc/self/fd is part of the userspace API.  The same thing might be 
true for O_RDONLY descriptors, but it's a bit less likely that there are 
any users out there.  In any case, I'm not sure it makes sense to plug 
the O_RDONLY hole while leaving the O_PATH hole open.

-- 
Florian Weimer / Red Hat Product Security Team