svn commit: r366189 - head/sys/fs/nfsserver

[Rick Macklem]

Author: rmacklem
Date: Sat Sep 26 23:05:38 2020
New Revision: 366189
URL: https://svnweb.freebsd.org/changeset/base/366189

Log:
  Bjorn reported a problem where the Linux NFSv4.1 client is
  using an open_to_lock_owner4 when that lock_owner4 has already
  been created by a previous open_to_lock_owner4. This caused the NFS server
  to reply NFSERR_INVAL.
  
  For NFSv4.0, this is an error, although the updated NFSv4.0 RFC7530 notes
  that the correct error reply is NFSERR_BADSEQID (RFC3530 did not specify
  what error to return).
  
  For NFSv4.1, it is not obvious whether or not this is allowed by RFC5661,
  but the NFSv4.1 server can handle this case without error.
  This patch changes the NFSv4.1 (and NFSv4.2) server to handle multiple
  uses of the same lock_owner in open_to_lock_owner so that it now correctly
  interoperates with the Linux NFS client.
  It also changes the error returned for NFSv4.0 to be NFSERR_BADSEQID.
  
  Thanks go to Bjorn for diagnosing this and testing the patch.
  He also provided a program that I could use to reproduce the problem.
  
  Tested by:	bj at cebitec.uni-bielefeld.de (Bjorn Fischer)
  PR:		249567
  Reported by:	bj at cebitec.uni-bielefeld.de (Bjorn Fischer)
  MFC after:	3 days

Modified:
  head/sys/fs/nfsserver/nfs_nfsdstate.c

Modified: head/sys/fs/nfsserver/nfs_nfsdstate.c
==============================================================================
--- head/sys/fs/nfsserver/nfs_nfsdstate.c	Sat Sep 26 21:47:11 2020	(r366188)
+++ head/sys/fs/nfsserver/nfs_nfsdstate.c	Sat Sep 26 23:05:38 2020	(r366189)
@@ -1870,14 +1870,20 @@ tryagain:
 			}
 			if (!error)
 			    nfsrv_getowner(&stp->ls_open, new_stp, &lckstp);
-			if (lckstp)
+			if (lckstp) {
 			    /*
-			     * I believe this should be an error, but it
-			     * isn't obvious what NFSERR_xxx would be
-			     * appropriate, so I'll use NFSERR_INVAL for now.
+			     * For NFSv4.1 and NFSv4.2 allow an
+			     * open_to_lock_owner when the lock_owner already
+			     * exists.  Just clear NFSLCK_OPENTOLOCK so that
+			     * a new lock_owner will not be created.
+			     * RFC7530 states that the error for NFSv4.0
+			     * is NFS4ERR_BAD_SEQID.
 			     */
-			    error = NFSERR_INVAL;
-			else
+			    if ((nd->nd_flag & ND_NFSV41) != 0)
+				new_stp->ls_flags &= ~NFSLCK_OPENTOLOCK;
+			    else
+				error = NFSERR_BADSEQID;
+			} else
 			    lckstp = new_stp;
 		    } else if (new_stp->ls_flags&(NFSLCK_LOCK|NFSLCK_UNLOCK)) {
 			/*