SUNRPC handle EKEYEXPIRED in call_refreshresult

Currently, when an RPCSEC_GSS context has expired or is non-existent
and the users (Kerberos) credentials have also expired or are non-existent,
the client receives the -EKEYEXPIRED error and tries to refresh the context
forever.  If an application is performing I/O, or other work against the share,
the application hangs, and the user is not prompted to refresh/establish their
credentials. This can result in a denial of service for other users.

Users are expected to manage their Kerberos credential lifetimes to mitigate
this issue.

Move the -EKEYEXPIRED handling into the RPC layer. Try tk_cred_retry number
of times to refresh the gss_context, and then return -EACCES to the application.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 69322096c325..70efb63b1e42 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -24,14 +24,14 @@
 
 #define NFSDBG_FACILITY         NFSDBG_PROC
 
-/* A wrapper to handle the EJUKEBOX and EKEYEXPIRED error messages */
+/* A wrapper to handle the EJUKEBOX error messages */
 static int
 nfs3_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 {
         int res;
         do {
                 res = rpc_call_sync(clnt, msg, flags);
-                if (res != -EJUKEBOX && res != -EKEYEXPIRED)
+                if (res != -EJUKEBOX)
                         break;
                 freezable_schedule_timeout_killable(NFS_JUKEBOX_RETRY_TIME);
                 res = -ERESTARTSYS;
@@ -44,7 +44,7 @@ nfs3_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 static int
 nfs3_async_handle_jukebox(struct rpc_task *task, struct inode *inode)
 {
-        if (task->tk_status != -EJUKEBOX && task->tk_status != -EKEYEXPIRED)
+        if (task->tk_status != -EJUKEBOX)
                 return 0;
         if (task->tk_status == -EJUKEBOX)
                 nfs_inc_stats(inode, NFSIOS_DELAY);