Re: [PATCH] cifs: handle termination of cifs oplockd kernel thread

From: J. Bruce Fields
Date: Sat Apr 30 2005 - 09:54:21 EST

On Sat, Apr 30, 2005 at 08:28:27AM -0500, Steve French wrote:
> Miklos Szeredi wrote:
> >>>- network/userspace filesystems should be fine aswell
> >>>
> >>>
> >>They should, but again I wonder if NFS with all it's complexity is
> >>being careful enough with what it accepts from the server.
> >>
> >>
> That is the fun of trying to get our network filesystems up to the
> 20th century. There is at lot more work that has to be done here, but
> it is gradually improving. At least for cifs but probably for NFSv4
> (and possibly AFS) it is possible for the client to validate that the
> server is who it says it is, and both NFSv4 (actually the newer NFS
> RPC) and CIFS of course allow packet signing which helps, not sure if
> AFS allows packet signing.

None of this helps in the situation Miklos is considering, where the
attacker is a user on the client doing the mount. So presumably the
user gets to choose a server under his/her control, and all the
authentication does is prove to the user that s/he got the right server,
which doesn't protect the kernel at all.

The only defense is auditing the client code's handling of data it
receives from the server.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at