[stable] SUNRPC handle EKEYEXPIRED in call_refreshresult

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On Tue, 2013-11-05 at 21:20 +0100, Bastian Blank wrote:
> On Tue, Nov 05, 2013 at 05:36:12PM +0100, Per Olofsson wrote:
> > Seems that maybe they reverted to the old behavior after all:
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=eb96d5c97b0825d542e9c4ba5e0a22b519355166

This is 'SUNRPC handle EKEYEXPIRED in call_refreshresult'.

> Okay.
> 
> Ben: can we fix that via longterm? The patch is a bit long.

Looks OK to me, though it needed some massaging (attaching my version).
Maybe I should also apply commit f1ff0c27fd99 ('SUNRPC: don't map
EKEYEXPIRED to EACCES in call_refreshresult')?

And if so, these should also go to the other relevant stable branches (<
3.8 for the first, < 3.12 for the second).

Ben.

-- 
Ben Hutchings
Teamwork is essential - it allows you to blame someone else.
From: Andy Adamson <andros@xxxxxxxxxx>
Date: Tue, 27 Nov 2012 10:34:19 -0500
Subject: SUNRPC handle EKEYEXPIRED in call_refreshresult

commit eb96d5c97b0825d542e9c4ba5e0a22b519355166 upstream.

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@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
[bwh: Backported to 3.2:
 - Adjust context
 - Drop change to nfs4_handle_reclaim_lease_error()]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 fs/nfs/nfs3proc.c       |  6 +++---
 fs/nfs/nfs4filelayout.c |  1 -
 fs/nfs/nfs4proc.c       | 18 ------------------
 fs/nfs/nfs4state.c      | 23 -----------------------
 fs/nfs/proc.c           | 43 -------------------------------------------
 net/sunrpc/clnt.c       |  1 +
 6 files changed, 4 insertions(+), 88 deletions(-)

--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -23,14 +23,14 @@
 
 #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;
 		schedule_timeout_killable(NFS_JUKEBOX_RETRY_TIME);
 		res = -ERESTARTSYS;
@@ -43,7 +43,7 @@ nfs3_rpc_wrapper(struct rpc_clnt *clnt,
 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);
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -103,7 +103,6 @@ static int filelayout_async_handle_error
 		break;
 	case -NFS4ERR_DELAY:
 	case -NFS4ERR_GRACE:
-	case -EKEYEXPIRED:
 		rpc_delay(task, FILELAYOUT_POLL_RETRY_MAX);
 		break;
 	case -NFS4ERR_RETRY_UNCACHED_REP:
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -315,7 +315,6 @@ static int nfs4_handle_exception(struct
 			}
 		case -NFS4ERR_GRACE:
 		case -NFS4ERR_DELAY:
-		case -EKEYEXPIRED:
 			ret = nfs4_delay(server->client, &exception->timeout);
 			if (ret != 0)
 				break;
@@ -1336,13 +1335,6 @@ int nfs4_open_delegation_recall(struct n
 				nfs_inode_find_state_and_recover(state->inode,
 						stateid);
 				nfs4_schedule_stateid_recovery(server, state);
-			case -EKEYEXPIRED:
-				/*
-				 * User RPCSEC_GSS context has expired.
-				 * We cannot recover this stateid now, so
-				 * skip it and allow recovery thread to
-				 * proceed.
-				 */
 			case -ENOMEM:
 				err = 0;
 				goto out;
@@ -3770,7 +3762,6 @@ nfs4_async_handle_error(struct rpc_task
 		case -NFS4ERR_DELAY:
 			nfs_inc_server_stats(server, NFSIOS_DELAY);
 		case -NFS4ERR_GRACE:
-		case -EKEYEXPIRED:
 			rpc_delay(task, NFS4_POLL_RETRY_MAX);
 			task->tk_status = 0;
 			return -EAGAIN;
@@ -4687,15 +4678,6 @@ int nfs4_lock_delegation_recall(struct n
 				nfs4_schedule_stateid_recovery(server, state);
 				err = 0;
 				goto out;
-			case -EKEYEXPIRED:
-				/*
-				 * User RPCSEC_GSS context has expired.
-				 * We cannot recover this stateid now, so
-				 * skip it and allow recovery thread to
-				 * proceed.
-				 */
-				err = 0;
-				goto out;
 			case -ENOMEM:
 			case -NFS4ERR_DENIED:
 				/* kill_proc(fl->fl_pid, SIGLOST, 1); */
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1211,14 +1211,6 @@ restart:
 				/* Mark the file as being 'closed' */
 				state->state = 0;
 				break;
-			case -EKEYEXPIRED:
-				/*
-				 * User RPCSEC_GSS context has expired.
-				 * We cannot recover this stateid now, so
-				 * skip it and allow recovery thread to
-				 * proceed.
-				 */
-				break;
 			case -NFS4ERR_ADMIN_REVOKED:
 			case -NFS4ERR_STALE_STATEID:
 			case -NFS4ERR_BAD_STATEID:
@@ -1371,14 +1363,6 @@ static void nfs4_state_start_reclaim_nog
 	nfs4_state_mark_reclaim_helper(clp, nfs4_state_mark_reclaim_nograce);
 }
 
-static void nfs4_warn_keyexpired(const char *s)
-{
-	printk_ratelimited(KERN_WARNING "Error: state manager"
-			" encountered RPCSEC_GSS session"
-			" expired against NFSv4 server %s.\n",
-			s);
-}
-
 static int nfs4_recovery_handle_error(struct nfs_client *clp, int error)
 {
 	switch (error) {
@@ -1410,10 +1394,6 @@ static int nfs4_recovery_handle_error(st
 			set_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
 			/* Zero session reset errors */
 			break;
-		case -EKEYEXPIRED:
-			/* Nothing we can do */
-			nfs4_warn_keyexpired(clp->cl_hostname);
-			break;
 		default:
 			return error;
 	}
@@ -1667,7 +1647,6 @@ static void nfs4_set_lease_expired(struc
 		break;
 
 	case -EKEYEXPIRED:
-		nfs4_warn_keyexpired(clp->cl_hostname);
 	case -NFS4ERR_NOT_SAME: /* FixMe: implement recovery
 				 * in nfs4_exchange_id */
 	default:
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -46,39 +46,6 @@
 #define NFSDBG_FACILITY		NFSDBG_PROC
 
 /*
- * wrapper to handle the -EKEYEXPIRED error message. This should generally
- * only happen if using krb5 auth and a user's TGT expires. NFSv2 doesn't
- * support the NFSERR_JUKEBOX error code, but we handle this situation in the
- * same way that we handle that error with NFSv3.
- */
-static int
-nfs_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
-{
-	int res;
-	do {
-		res = rpc_call_sync(clnt, msg, flags);
-		if (res != -EKEYEXPIRED)
-			break;
-		schedule_timeout_killable(NFS_JUKEBOX_RETRY_TIME);
-		res = -ERESTARTSYS;
-	} while (!fatal_signal_pending(current));
-	return res;
-}
-
-#define rpc_call_sync(clnt, msg, flags)	nfs_rpc_wrapper(clnt, msg, flags)
-
-static int
-nfs_async_handle_expired_key(struct rpc_task *task)
-{
-	if (task->tk_status != -EKEYEXPIRED)
-		return 0;
-	task->tk_status = 0;
-	rpc_restart_call(task);
-	rpc_delay(task, NFS_JUKEBOX_RETRY_TIME);
-	return 1;
-}
-
-/*
  * Bare-bones access to getattr: this is for nfs_read_super.
  */
 static int
@@ -359,8 +326,6 @@ nfs_proc_unlink_setup(struct rpc_message
 
 static int nfs_proc_unlink_done(struct rpc_task *task, struct inode *dir)
 {
-	if (nfs_async_handle_expired_key(task))
-		return 0;
 	nfs_mark_for_revalidate(dir);
 	return 1;
 }
@@ -375,8 +340,6 @@ static int
 nfs_proc_rename_done(struct rpc_task *task, struct inode *old_dir,
 		     struct inode *new_dir)
 {
-	if (nfs_async_handle_expired_key(task))
-		return 0;
 	nfs_mark_for_revalidate(old_dir);
 	nfs_mark_for_revalidate(new_dir);
 	return 1;
@@ -630,9 +593,6 @@ nfs_proc_pathconf(struct nfs_server *ser
 
 static int nfs_read_done(struct rpc_task *task, struct nfs_read_data *data)
 {
-	if (nfs_async_handle_expired_key(task))
-		return -EAGAIN;
-
 	nfs_invalidate_atime(data->inode);
 	if (task->tk_status >= 0) {
 		nfs_refresh_inode(data->inode, data->res.fattr);
@@ -652,9 +612,6 @@ static void nfs_proc_read_setup(struct n
 
 static int nfs_write_done(struct rpc_task *task, struct nfs_write_data *data)
 {
-	if (nfs_async_handle_expired_key(task))
-		return -EAGAIN;
-
 	if (task->tk_status >= 0)
 		nfs_post_op_update_inode_force_wcc(data->inode, data->res.fattr);
 	return 0;
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1007,6 +1007,7 @@ call_refreshresult(struct rpc_task *task
 		return;
 	case -ETIMEDOUT:
 		rpc_delay(task, 3*HZ);
+	case -EKEYEXPIRED:
 	case -EAGAIN:
 		status = -EACCES;
 		if (!task->tk_cred_retry)

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