[RFC PATCH] NFSD: Replace use of NFSD_MAY_LOCK in nfsd4_lock()

[cel@kernel.org]

From: Chuck Lever <chuck.lever@oracle.com>

NFSv4 LOCK operations should not avoid the set of authorization
checks that apply to all other NFSv4 operations. Also, the
"no_auth_nlm" export option should apply only to NLM LOCK requests.
It's not necessary or sensible to apply it to NFSv4 LOCK operations.

The replacement MAY bit mask,
"NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE", comes from the access
bits that are set in nfsd_permission() when the caller has set
NFSD_MAY_LOCK.

Reported-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4state.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9c2b1d251ab3..3f2c11414390 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7967,11 +7967,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (check_lock_length(lock->lk_offset, lock->lk_length))
 		 return nfserr_inval;
 
-	if ((status = fh_verify(rqstp, &cstate->current_fh,
-				S_IFREG, NFSD_MAY_LOCK))) {
-		dprintk("NFSD: nfsd4_lock: permission denied!\n");
+	status = fh_verify(rqstp, &cstate->current_fh, S_IFREG,
+			   NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE);
+	if (status != nfs_ok)
 		return status;
-	}
 	sb = cstate->current_fh.fh_dentry->d_sb;
 
 	if (lock->lk_is_new) {
-- 
2.46.2