RPC: Make rpc_auth credential cache optional.

  Some RPC authentication flavours are not related to the uid (AUTH_NULL
  springs to mind). This patch moves control over the caching mechanism
  into the auth-specific code.

  Also ensure that expired creds are removed from the cache.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/auth.h

@@ -91,6 +91,7 @@ struct rpc_authops {
 	struct rpc_auth *	(*create)(struct rpc_clnt *, rpc_authflavor_t);
 	void			(*destroy)(struct rpc_auth *);
 
+	struct rpc_cred *	(*lookup_cred)(struct rpc_auth *, struct auth_cred *, int);
 	struct rpc_cred *	(*crcreate)(struct rpc_auth*, struct auth_cred *, int);
 };
 

net/sunrpc/auth.c

@@ -137,16 +137,17 @@ rpcauth_free_credcache(struct rpc_auth *auth)
 	rpcauth_destroy_credlist(&free);
 }
 
-static inline int
+static void
 rpcauth_prune_expired(struct rpc_cred *cred, struct list_head *free)
 {
 	if (atomic_read(&cred->cr_count) != 1)
-	       return 0;
-	if (time_before(jiffies, cred->cr_expire + cred->cr_auth->au_expire))
-		return 0;
-	cred->cr_auth = NULL;
-	list_move(&cred->cr_hash, free);
-	return 1;
+	       return;
+	if (time_after(jiffies, cred->cr_expire + cred->cr_auth->au_expire))
+		cred->cr_flags &= ~RPCAUTH_CRED_UPTODATE;
+	if (!(cred->cr_flags & RPCAUTH_CRED_UPTODATE)) {
+		cred->cr_auth = NULL;
+		list_move(&cred->cr_hash, free);
+	}
 }
 
 /*
@@ -191,13 +192,12 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
 	list_for_each_safe(pos, next, &auth->au_credcache[nr]) {
 		struct rpc_cred *entry;
 	       	entry = list_entry(pos, struct rpc_cred, cr_hash);
-		if (rpcauth_prune_expired(entry, &free))
-			continue;
 		if (entry->cr_ops->crmatch(acred, entry, taskflags)) {
 			list_del(&entry->cr_hash);
 			cred = entry;
 			break;
 		}
+		rpcauth_prune_expired(entry, &free);
 	}
 	if (new) {
 		if (cred)
@@ -240,7 +240,7 @@ rpcauth_lookupcred(struct rpc_auth *auth, int taskflags)
 
 	dprintk("RPC:     looking up %s cred\n",
 		auth->au_ops->au_name);
-	ret = rpcauth_lookup_credcache(auth, &acred, taskflags);
+	ret = auth->au_ops->lookup_cred(auth, &acred, taskflags);
 	put_group_info(current->group_info);
 	return ret;
 }
@@ -259,7 +259,7 @@ rpcauth_bindcred(struct rpc_task *task)
 
 	dprintk("RPC: %4d looking up %s cred\n",
 		task->tk_pid, task->tk_auth->au_ops->au_name);
-	task->tk_msg.rpc_cred = rpcauth_lookup_credcache(auth, &acred, task->tk_flags);
+	task->tk_msg.rpc_cred = auth->au_ops->lookup_cred(auth, &acred, task->tk_flags);
 	if (task->tk_msg.rpc_cred == 0)
 		task->tk_status = -ENOMEM;
 	ret = task->tk_msg.rpc_cred;

net/sunrpc/auth_gss/auth_gss.c

@@ -654,6 +654,15 @@ gss_destroy_cred(struct rpc_cred *rc)
 	kfree(cred);
 }
 
+/*
+ * Lookup RPCSEC_GSS cred for the current process
+ */
+static struct rpc_cred *
+gss_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int taskflags)
+{
+	return rpcauth_lookup_credcache(auth, acred, taskflags);
+}
+
 static struct rpc_cred *
 gss_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int taskflags)
 {
@@ -1004,6 +1013,7 @@ static struct rpc_authops authgss_ops = {
 #endif
 	.create		= gss_create,
 	.destroy	= gss_destroy,
+	.lookup_cred	= gss_lookup_cred,
 	.crcreate	= gss_create_cred
 };
 

net/sunrpc/auth_null.c

@@ -46,6 +46,15 @@ nul_destroy(struct rpc_auth *auth)
 	kfree(auth);
 }
 
+/*
+ * Lookup NULL creds for current process
+ */
+static struct rpc_cred *
+nul_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
+{
+	return rpcauth_lookup_credcache(auth, acred, flags);
+}
+
 /*
  * Create NULL creds for current process
  */
@@ -135,6 +144,7 @@ struct rpc_authops	authnull_ops = {
 #endif
 	.create		= nul_create,
 	.destroy	= nul_destroy,
+	.lookup_cred	= nul_lookup_cred,
 	.crcreate	= nul_create_cred,
 };
 

net/sunrpc/auth_unix.c

@@ -65,6 +65,15 @@ unx_destroy(struct rpc_auth *auth)
 	kfree(auth);
 }
 
+/*
+ * Lookup AUTH_UNIX creds for current process
+ */
+static struct rpc_cred *
+unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
+{
+	return rpcauth_lookup_credcache(auth, acred, flags);
+}
+
 static struct rpc_cred *
 unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
 {
@@ -225,6 +234,7 @@ struct rpc_authops	authunix_ops = {
 #endif
 	.create		= unx_create,
 	.destroy	= unx_destroy,
+	.lookup_cred	= unx_lookup_cred,
 	.crcreate	= unx_create_cred,
 };