SUNRPC/nfs: Fix return value for nfs4_callback_compound()

RPC server procedures are normally expected to return a __be32 encoded
status value of type 'enum rpc_accept_stat', however at least one function
wants to return an authentication status of type 'enum rpc_auth_stat'
in the case where authentication fails.
This patch adds functionality to allow this.

Fixes: a4e187d8 ("NFS: Don't drop CB requests with invalid principals")
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfs/callback_xdr.c

@@ -983,7 +983,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp)
 
 out_invalidcred:
 	pr_warn_ratelimited("NFS: NFSv4 callback contains invalid cred\n");
-	return rpc_autherr_badcred;
+	return svc_return_autherr(rqstp, rpc_autherr_badcred);
 }
 
 /*

include/linux/sunrpc/svc.h

@@ -271,6 +271,7 @@ struct svc_rqst {
 #define	RQ_VICTIM	(5)			/* about to be shut down */
 #define	RQ_BUSY		(6)			/* request is busy */
 #define	RQ_DATA		(7)			/* request has data */
+#define RQ_AUTHERR	(8)			/* Request status is auth error */
 	unsigned long		rq_flags;	/* flags field */
 	ktime_t			rq_qtime;	/* enqueue time */
 
@@ -504,6 +505,7 @@ unsigned int	   svc_fill_write_vector(struct svc_rqst *rqstp,
 char		  *svc_fill_symlink_pathname(struct svc_rqst *rqstp,
 					     struct kvec *first, void *p,
 					     size_t total);
+__be32		   svc_return_autherr(struct svc_rqst *rqstp, __be32 auth_err);
 
 #define	RPC_MAX_ADDRBUFLEN	(63U)
 

net/sunrpc/svc.c

@@ -1144,6 +1144,22 @@ void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...)
 static __printf(2,3) void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) {}
 #endif
 
+__be32
+svc_return_autherr(struct svc_rqst *rqstp, __be32 auth_err)
+{
+	set_bit(RQ_AUTHERR, &rqstp->rq_flags);
+	return auth_err;
+}
+EXPORT_SYMBOL_GPL(svc_return_autherr);
+
+static __be32
+svc_get_autherr(struct svc_rqst *rqstp, __be32 *statp)
+{
+	if (test_and_clear_bit(RQ_AUTHERR, &rqstp->rq_flags))
+		return *statp;
+	return rpc_auth_ok;
+}
+
 /*
  * Common routine for processing the RPC request.
  */
@@ -1290,11 +1306,9 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 				procp->pc_release(rqstp);
 			goto dropit;
 		}
-		if (*statp == rpc_autherr_badcred) {
-			if (procp->pc_release)
-				procp->pc_release(rqstp);
-			goto err_bad_auth;
-		}
+		auth_stat = svc_get_autherr(rqstp, statp);
+		if (auth_stat != rpc_auth_ok)
+			goto err_release_bad_auth;
 		if (*statp == rpc_success && procp->pc_encode &&
 		    !procp->pc_encode(rqstp, resv->iov_base + resv->iov_len)) {
 			dprintk("svc: failed to encode reply\n");
@@ -1351,6 +1365,9 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
 	svc_putnl(resv, 2);
 	goto sendit;
 
+err_release_bad_auth:
+	if (procp->pc_release)
+		procp->pc_release(rqstp);
 err_bad_auth:
 	dprintk("svc: authentication failed (%d)\n", ntohl(auth_stat));
 	serv->sv_stats->rpcbadauth++;