tls: Fix TLS ulp context leak, when TLS_TX setsockopt is not used.

commit ff45d820 upstream.

Previously the TLS ulp context would leak if we attached a TLS ulp
to a socket but did not use the TLS_TX setsockopt,
or did use it but it failed.
This patch solves the issue by overriding prot[TLS_BASE_TX].close
and fixing tls_sk_proto_close to work properly
when its called with ctx->tx_conf == TLS_BASE_TX.
This patch also removes ctx->free_resources as we can use ctx->tx_conf
to obtain the relevant information.

Fixes: 3c4d7559 ('tls: kernel TLS support')
Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 4.14: Keep using tls_ctx_free() as introduced by
 the earlier backport of "tls: zero the crypto information from
 tls_context before freeing"]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

include/net/tls.h

@@ -106,7 +106,6 @@ struct tls_context {
 
 	u16 pending_open_record_frags;
 	int (*push_pending_record)(struct sock *sk, int flags);
-	void (*free_resources)(struct sock *sk);
 
 	void (*sk_write_space)(struct sock *sk);
 	void (*sk_proto_close)(struct sock *sk, long timeout);
@@ -131,6 +130,7 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 int tls_sw_sendpage(struct sock *sk, struct page *page,
 		    int offset, size_t size, int flags);
 void tls_sw_close(struct sock *sk, long timeout);
+void tls_sw_free_tx_resources(struct sock *sk);
 
 void tls_sk_destruct(struct sock *sk, struct tls_context *ctx);
 void tls_icsk_clean_acked(struct sock *sk);

net/tls/tls_main.c

@@ -249,6 +249,12 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
 	void (*sk_proto_close)(struct sock *sk, long timeout);
 
 	lock_sock(sk);
+	sk_proto_close = ctx->sk_proto_close;
+
+	if (ctx->tx_conf == TLS_BASE_TX) {
+		tls_ctx_free(ctx);
+		goto skip_tx_cleanup;
+	}
 
 	if (!tls_complete_pending_work(sk, ctx, 0, &timeo))
 		tls_handle_open_record(sk, 0);
@@ -265,13 +271,16 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
 			sg++;
 		}
 	}
-	ctx->free_resources(sk);
+
 	kfree(ctx->rec_seq);
 	kfree(ctx->iv);
 
-	sk_proto_close = ctx->sk_proto_close;
+	if (ctx->tx_conf == TLS_SW_TX) {
+		tls_sw_free_tx_resources(sk);
 		tls_ctx_free(ctx);
+	}
 
+skip_tx_cleanup:
 	release_sock(sk);
 	sk_proto_close(sk, timeout);
 }
@@ -428,8 +437,6 @@ static int do_tls_setsockopt_tx(struct sock *sk, char __user *optval,
 	ctx->sk_write_space = sk->sk_write_space;
 	sk->sk_write_space = tls_write_space;
 
-	ctx->sk_proto_close = sk->sk_prot->close;
-
 	/* currently SW is default, we will have ethtool in future */
 	rc = tls_set_sw_offload(sk, ctx);
 	tx_conf = TLS_SW_TX;
@@ -499,6 +506,7 @@ static int tls_init(struct sock *sk)
 	icsk->icsk_ulp_data = ctx;
 	ctx->setsockopt = sk->sk_prot->setsockopt;
 	ctx->getsockopt = sk->sk_prot->getsockopt;
+	ctx->sk_proto_close = sk->sk_prot->close;
 
 	ctx->tx_conf = TLS_BASE_TX;
 	update_sk_prot(sk, ctx);
@@ -517,9 +525,9 @@ static void build_protos(struct proto *prot, struct proto *base)
 	prot[TLS_BASE_TX] = *base;
 	prot[TLS_BASE_TX].setsockopt	= tls_setsockopt;
 	prot[TLS_BASE_TX].getsockopt	= tls_getsockopt;
+	prot[TLS_BASE_TX].close		= tls_sk_proto_close;
 
 	prot[TLS_SW_TX] = prot[TLS_BASE_TX];
-	prot[TLS_SW_TX].close		= tls_sk_proto_close;
 	prot[TLS_SW_TX].sendmsg		= tls_sw_sendmsg;
 	prot[TLS_SW_TX].sendpage	= tls_sw_sendpage;
 }

net/tls/tls_sw.c

@@ -646,7 +646,7 @@ int tls_sw_sendpage(struct sock *sk, struct page *page,
 	return ret;
 }
 
-static void tls_sw_free_resources(struct sock *sk)
+void tls_sw_free_tx_resources(struct sock *sk)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context *ctx = tls_sw_ctx(tls_ctx);
@@ -685,7 +685,6 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx)
 	}
 
 	ctx->priv_ctx = (struct tls_offload_context *)sw_ctx;
-	ctx->free_resources = tls_sw_free_resources;
 
 	crypto_info = &ctx->crypto_send.info;
 	switch (crypto_info->cipher_type) {