The duplicate information returned in fa_type and fa_mode

is an ambiguity in the NFS version 2 protocol.

VREG should be taken literally as a regular file.  If a
server intents to return some type information differently
in the upper bits of the mode field (e.g. for sockets, or
FIFOs), NFSv2 mandates fa_type to be VNON.  Anyway, we
leave the examination of the mode bits even in the VREG
case to avoid breakage for bogus servers, but we make sure
that there are actually type bits set in the upper part of
fa_mode (and failing that, trust the va_type field).

NFSv3 cleared the issue, and requires fa_mode to not
contain any type information (while also introduing sockets
and FIFOs for fa_type).

The fix has been tested against a variety of NFS servers.
It fixes problems with the ``Tropic'' NFS server for Windows,
while apparently not breaking anything.

Pointed-out by: scott@zorch.sf-bay.org (Scott Hazen Mueller)

1 files changed, 21 insertions, 2 deletions

diff --git a/sys/nfsserver/nfs_srvsubs.c b/sys/nfsserver/nfs_srvsubs.c
index 9aeb0d6..1653c8b 100644
--- a/sys/nfsserver/nfs_srvsubs.c
+++ b/sys/nfsserver/nfs_srvsubs.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)nfs_subs.c	8.3 (Berkeley) 1/4/94
- * $Id: nfs_subs.c,v 1.14 1995/05/29 04:01:09 davidg Exp $
+ * $Id: nfs_subs.c,v 1.15 1995/05/30 08:12:43 rgrimes Exp $
  */
 
 /*
@@ -712,7 +712,26 @@ nfs_loadattrcache(vpp, mdp, dposp, vaper)
 	fp = (struct nfsv2_fattr *)cp2;
 	vtyp = nfstov_type(fp->fa_type);
 	vmode = fxdr_unsigned(u_short, fp->fa_mode);
-	if (vtyp == VNON || vtyp == VREG)
+	/*
+	 * XXX
+	 *
+	 * The duplicate information returned in fa_type and fa_mode
+	 * is an ambiguity in the NFS version 2 protocol.
+	 *
+	 * VREG should be taken literally as a regular file.  If a
+	 * server intents to return some type information differently
+	 * in the upper bits of the mode field (e.g. for sockets, or
+	 * FIFOs), NFSv2 mandates fa_type to be VNON.  Anyway, we
+	 * leave the examination of the mode bits even in the VREG
+	 * case to avoid breakage for bogus servers, but we make sure
+	 * that there are actually type bits set in the upper part of
+	 * fa_mode (and failing that, trust the va_type field).
+	 *
+	 * NFSv3 cleared the issue, and requires fa_mode to not
+	 * contain any type information (while also introduing sockets
+	 * and FIFOs for fa_type).
+	 */
+	if (vtyp == VNON || (vtyp == VREG && (vmode & S_IFMT) != 0))
 		vtyp = IFTOVT(vmode);
 	if (isnq) {
 		rdev = fxdr_unsigned(long, fp->fa_nqrdev);