nfsd4: allow an EXCHANGE_ID to kill a 4.0 client

Following rfc 5661 section 2.4.1, we can permit a 4.1 client to remove
an established 4.0 client's state.

(But we don't allow updates.)

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f372a6edef34..c88f5c103e87 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1553,8 +1553,10 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
         conf = find_confirmed_client_by_str(dname, strhashval);
         if (conf) {
                 if (!clp_used_exchangeid(conf)) {
-                        status = nfserr_clid_inuse; /* XXX: ? */
-                        goto out;
+                        if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
+                                status = nfserr_inval; /* buggy client */
+                                goto out;
+                        }
                 }
                 if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
                         /* 18.35.4 case 9 */
@@ -1574,6 +1576,10 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
                         expire_client(conf);
                         goto out_new;
                 }
+                if (!clp_used_exchangeid(conf)) {
+                        status = nfserr_inval;
+                        goto out;
+                }
                 /*
                  * Set bit when the owner id and verifier map to an already
                  * confirmed client id (18.35.3).