On Fri, Aug 21, 2009 at 05:08:12PM -0400, Trond Myklebust wrote: > On Fri, 2009-08-21 at 16:59 -0400, J. Bruce Fields wrote: > > On Fri, Aug 21, 2009 at 04:39:53PM -0400, Peter Staubach wrote: > > > Tom Haynes wrote: > > > > J. Bruce Fields wrote: > > > >> > > > >>> Right now, we use AUTH_SYS if the mount command didn't specify a > > > >>> flavor, but the flavor we're going to use is always checked against > > > >>> the server's returned list. You seem to be suggesting we should > > > >>> ignore the server's list entirely if sec= was specified...? > > > >>> > > > >> > > > >> Yes. I can't see what practical problems that would cause. > > > >> > > > > > > Here, I am going to disagree. The client should compare the > > > flavor specified with the list of authentication flavors > > > returned by the server and if the specific flavor isn't on > > > the list, then the mount attempt should be failed. > > > > Why? What can go wrong if you just try the flavor? > > > > Ugh: to answer my own question: ok, if the server allows auth_sys for > > the NFS operations required on mount (as suggested by the security > > considerations rfc), then that would mean mount would always succeed, > > and nobody would see the error until the first operation on the > > filesystem. It would be better to return the error on mount. > > > > So, I think I have to give in and agree with you. People will just have > > to upgrade their mountd's.... > > People have lived with the current situation for years without any > trouble. It was only the addition of the security negotiation that > exposed the mountd bug. > > My position is that if mountd returns a clearly invalid (i.e. empty) > list, then that's not a reason to interrupt the mount. We should just > fall back to what we did prior to including security negotiation. Yeah, so instead of taking my original pseudocode (which just allowed sec= to always override even a non-empty list from the server), more reasonable might be just to treat the empty-list case specially. For example, maybe: - If the returned list is nonempty: - Do whatever the latest code does: probably return an error if there's a clash with the sec= mount option, otherwise attempt the first on the list. - Otherwise, if the returned list is empty: - Use any sec= option if provide, or auth_sys if not. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
