Commit 5eecfde6 authored Aug 21, 2009 by Chuck Lever Committed by Trond Myklebust Aug 23, 2009

NFS: Handle a zero-length auth flavor list



Some releases of Linux rpc.mountd (nfs-utils 1.1.4 and later) return an
empty auth flavor list if no sec= was specified for the export.  This is
notably broken server behavior.

The new auth flavor list checking added in a recent commit rejects this
case.  The OpenSolaris client does too.

The broken mountd implementation is already widely deployed.  To avoid
a behavioral regression, the kernel's mount client skips flavor checking
(ie reverts to the pre-2.6.32 behavior) if mountd returns an empty
flavor list.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

parent 405d8f8b

fs/nfs/super.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -1337,6 +1337,16 @@ static int nfs_walk_authlist(struct nfs_parsed_mount_data *args,
		{
		unsigned int i, j, server_authlist_len = *(request->auth_flav_len);

		/*
		* Certain releases of Linux's mountd return an empty
		* flavor list. To prevent behavioral regression with
		* these servers (ie. rejecting mounts that used to
		* succeed), revert to pre-2.6.32 behavior (no checking)
		* if the returned flavor list is empty.
		*/
		if (server_authlist_len == 0)
		return 0;

		/*
		* We avoid sophisticated negotiating here, as there are
		* plenty of cases where we can get it wrong, providing

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