From ac4315936959d8b54c2904bf0503d24088b82c73 Mon Sep 17 00:00:00 2001
From: Vadim Fedorenko <vfedorenko@novek.ru>
Date: Wed, 20 May 2020 11:41:43 +0300
Subject: [PATCH] net/tls: fix encryption error checking

commit a7bff11f6f9afa87c25711db8050c9b5324db0e2 upstream.

bpf_exec_tx_verdict() can return negative value for copied
variable. In that case this value will be pushed back to caller
and the real error code will be lost. Fix it using signed type and
checking for positive value.

Fixes: d10523d0b3d7 ("net/tls: free the record on encryption error")
Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling")
Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 4d7c3b5f3af2..f9001c62ec80 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -777,7 +777,7 @@ static int tls_push_record(struct sock *sk, int flags,
 
 static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
 			       bool full_record, u8 record_type,
-			       size_t *copied, int flags)
+			       ssize_t *copied, int flags)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_tx *ctx = tls_sw_ctx_tx(tls_ctx);
@@ -911,7 +911,8 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	unsigned char record_type = TLS_RECORD_TYPE_DATA;
 	bool is_kvec = iov_iter_is_kvec(&msg->msg_iter);
 	bool eor = !(msg->msg_flags & MSG_MORE);
-	size_t try_to_copy, copied = 0;
+	size_t try_to_copy;
+	ssize_t copied = 0;
 	struct sk_msg *msg_pl, *msg_en;
 	struct tls_rec *rec;
 	int required_size;
@@ -1113,7 +1114,7 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 
 	release_sock(sk);
 	mutex_unlock(&tls_ctx->tx_lock);
-	return copied ? copied : ret;
+	return copied > 0 ? copied : ret;
 }
 
 static int tls_sw_do_sendpage(struct sock *sk, struct page *page,
@@ -1127,7 +1128,7 @@ static int tls_sw_do_sendpage(struct sock *sk, struct page *page,
 	struct sk_msg *msg_pl;
 	struct tls_rec *rec;
 	int num_async = 0;
-	size_t copied = 0;
+	ssize_t copied = 0;
 	bool full_record;
 	int record_room;
 	int ret = 0;
@@ -1229,7 +1230,7 @@ static int tls_sw_do_sendpage(struct sock *sk, struct page *page,
 	}
 sendpage_end:
 	ret = sk_stream_error(sk, flags, ret);
-	return copied ? copied : ret;
+	return copied > 0 ? copied : ret;
 }
 
 int tls_sw_sendpage_locked(struct sock *sk, struct page *page,
-- 
2.7.4