From: Chuck Lever <chuck.lever@oracle.com>

Date: Tue, 2 May 2023 14:59:10 -0400

Subject: SUNRPC: Fix encoding of accepted but unsuccessful RPC replies

Git-commit: 29cd2927fb914cc53b5ba4f67d2b74695c994ba4

Patch-mainline: 6.4-rc3

References: bsc#1210995

Jiri Slaby says:

> I bisected to this ... as it breaks nfs3-only servers in 6.3.

> I.e. /etc/nfs.conf containing:

> [nfsd]

> vers4=no

>

> The client sees:

>  mount("10.0.2.15:/tmp", "/mnt", "nfs", 0, "vers=4.2,addr=10.0.2.15,clientad"...) = -1 EIO (Input/output error)

>  write(2, "mount.nfs: mount system call fai"..., 45

>  mount.nfs: mount system call failed for /mnt

>

> And the kernel says:

>  nfs4_discover_server_trunking unhandled error -5. Exiting with error EIO

Reported-by: Jiri Slaby <jirislaby@kernel.org>

Link: https://bugzilla.suse.com/show_bug.cgi?id=1210995

Fixes: 4bcf0343e8a6 ("SUNRPC: Set rq_accept_statp inside ->accept methods")

Tested-by: Jiri Slaby <jirislaby@kernel.org>

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Signed-off-by: Jiri Slaby <jslaby@suse.cz>

---

 net/sunrpc/svc.c |   17 +++++++++++------

 1 file changed, 11 insertions(+), 6 deletions(-)

--- a/net/sunrpc/svc.c

+++ b/net/sunrpc/svc.c

@@ -1382,7 +1382,7 @@ err_bad_rpc:

 	/* Only RPCv2 supported */

 	xdr_stream_encode_u32(xdr, RPC_VERSION);

 	xdr_stream_encode_u32(xdr, RPC_VERSION);

-	goto sendit;

+	return 1;	/* don't wrap */

 err_bad_auth:

 	dprintk("svc: authentication failed (%d)\n",

@@ -1398,7 +1398,7 @@ err_bad_auth:

 err_bad_prog:

 	dprintk("svc: unknown program %d\n", rqstp->rq_prog);

 	serv->sv_stats->rpcbadfmt++;

-	xdr_stream_encode_u32(xdr, RPC_PROG_UNAVAIL);

+	*rqstp->rq_accept_statp = rpc_prog_unavail;

 	goto sendit;

 err_bad_vers:

@@ -1406,7 +1406,12 @@ err_bad_vers:

 		       rqstp->rq_vers, rqstp->rq_prog, progp->pg_name);

 	serv->sv_stats->rpcbadfmt++;

-	xdr_stream_encode_u32(xdr, RPC_PROG_MISMATCH);

+	*rqstp->rq_accept_statp = rpc_prog_mismatch;

+

+	/*

+	 * svc_authenticate() has already added the verifier and

+	 * advanced the stream just past rq_accept_statp.

+	 */

 	xdr_stream_encode_u32(xdr, process.mismatch.lovers);

 	xdr_stream_encode_u32(xdr, process.mismatch.hivers);

 	goto sendit;

@@ -1415,19 +1420,19 @@ err_bad_proc:

 	svc_printk(rqstp, "unknown procedure (%d)\n", rqstp->rq_proc);

 	serv->sv_stats->rpcbadfmt++;

-	xdr_stream_encode_u32(xdr, RPC_PROC_UNAVAIL);

+	*rqstp->rq_accept_statp = rpc_proc_unavail;

 	goto sendit;

 err_garbage_args:

 	svc_printk(rqstp, "failed to decode RPC header\n");

 	serv->sv_stats->rpcbadfmt++;

-	xdr_stream_encode_u32(xdr, RPC_GARBAGE_ARGS);

+	*rqstp->rq_accept_statp = rpc_garbage_args;

 	goto sendit;

 err_system_err:

 	serv->sv_stats->rpcbadfmt++;

-	xdr_stream_encode_u32(xdr, RPC_SYSTEM_ERR);

+	*rqstp->rq_accept_statp = rpc_system_err;

 	goto sendit;

 }