Patch "SUNRPC: Fail quickly when server does not recognize TLS" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    SUNRPC: Fail quickly when server does not recognize TLS

to the 6.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sunrpc-fail-quickly-when-server-does-not-recognize-t.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e18117f24271eb5a06d938c44d09accb8f1fbb61
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Wed Sep 6 16:05:26 2023 -0400

    SUNRPC: Fail quickly when server does not recognize TLS
    
    [ Upstream commit 5623ecfcbec165f040a23248d39680f0cc5c0854 ]
    
    rpcauth_checkverf() should return a distinct error code when a
    server recognizes the AUTH_TLS probe but does not support TLS so
    that the client's header decoder can respond appropriately and
    quickly. No retries are necessary is in this case, since the server
    has already affirmatively answered "TLS is unsupported".
    
    Suggested-by: Trond Myklebust <trondmy@xxxxxxxxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 2f16f9d179662..814b0169f9723 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -769,9 +769,14 @@ int rpcauth_wrap_req(struct rpc_task *task, struct xdr_stream *xdr)
  * @task: controlling RPC task
  * @xdr: xdr_stream containing RPC Reply header
  *
- * On success, @xdr is updated to point past the verifier and
- * zero is returned. Otherwise, @xdr is in an undefined state
- * and a negative errno is returned.
+ * Return values:
+ *   %0: Verifier is valid. @xdr now points past the verifier.
+ *   %-EIO: Verifier is corrupted or message ended early.
+ *   %-EACCES: Verifier is intact but not valid.
+ *   %-EPROTONOSUPPORT: Server does not support the requested auth type.
+ *
+ * When a negative errno is returned, @xdr is left in an undefined
+ * state.
  */
 int
 rpcauth_checkverf(struct rpc_task *task, struct xdr_stream *xdr)
diff --git a/net/sunrpc/auth_tls.c b/net/sunrpc/auth_tls.c
index de7678f8a23d2..87f570fd3b00e 100644
--- a/net/sunrpc/auth_tls.c
+++ b/net/sunrpc/auth_tls.c
@@ -129,9 +129,9 @@ static int tls_validate(struct rpc_task *task, struct xdr_stream *xdr)
 	if (*p != rpc_auth_null)
 		return -EIO;
 	if (xdr_stream_decode_opaque_inline(xdr, &str, starttls_len) != starttls_len)
-		return -EIO;
+		return -EPROTONOSUPPORT;
 	if (memcmp(str, starttls_token, starttls_len))
-		return -EIO;
+		return -EPROTONOSUPPORT;
 	return 0;
 }
 
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index be6be7d785315..9fb0ccabc1a26 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2721,7 +2721,15 @@ rpc_decode_header(struct rpc_task *task, struct xdr_stream *xdr)
 
 out_verifier:
 	trace_rpc_bad_verifier(task);
-	goto out_garbage;
+	switch (error) {
+	case -EPROTONOSUPPORT:
+		goto out_err;
+	case -EACCES:
+		/* Re-encode with a fresh cred */
+		fallthrough;
+	default:
+		goto out_garbage;
+	}
 
 out_msg_denied:
 	error = -EACCES;