From eda7acddf8080bb2d022a8d4b8b2345eb80c63ec Mon Sep 17 00:00:00 2001
From: Peter Krystad <peter.krystad@linux.intel.com>
Date: Tue, 21 Jan 2020 16:56:16 -0800
Subject: mptcp: Handle MPTCP TCP options

Add hooks to parse and format the MP_CAPABLE option.

This option is handled according to MPTCP version 0 (RFC6824).
MPTCP version 1 MP_CAPABLE (RFC6824bis/RFC8684) will be added later in
coordination with related code changes.

Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/tcp_input.c  |  5 +++++
 net/ipv4/tcp_output.c | 13 +++++++++++++
 2 files changed, 18 insertions(+)

(limited to 'net/ipv4')

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 358365598216..3458ee13e6f0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -79,6 +79,7 @@
 #include <trace/events/tcp.h>
 #include <linux/jump_label_ratelimit.h>
 #include <net/busy_poll.h>
+#include <net/mptcp.h>
 
 int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 
@@ -3924,6 +3925,10 @@ void tcp_parse_options(const struct net *net,
 				 */
 				break;
 #endif
+			case TCPOPT_MPTCP:
+				mptcp_parse_option(ptr, opsize, opt_rx);
+				break;
+
 			case TCPOPT_FASTOPEN:
 				tcp_parse_fastopen_option(
 					opsize - TCPOLEN_FASTOPEN_BASE,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 786978cb2db7..0f0984f39f67 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -38,6 +38,7 @@
 #define pr_fmt(fmt) "TCP: " fmt
 
 #include <net/tcp.h>
+#include <net/mptcp.h>
 
 #include <linux/compiler.h>
 #include <linux/gfp.h>
@@ -414,6 +415,7 @@ static inline bool tcp_urg_mode(const struct tcp_sock *tp)
 #define OPTION_WSCALE		(1 << 3)
 #define OPTION_FAST_OPEN_COOKIE	(1 << 8)
 #define OPTION_SMC		(1 << 9)
+#define OPTION_MPTCP		(1 << 10)
 
 static void smc_options_write(__be32 *ptr, u16 *options)
 {
@@ -439,8 +441,17 @@ struct tcp_out_options {
 	__u8 *hash_location;	/* temporary pointer, overloaded */
 	__u32 tsval, tsecr;	/* need to include OPTION_TS */
 	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
+	struct mptcp_out_options mptcp;
 };
 
+static void mptcp_options_write(__be32 *ptr, struct tcp_out_options *opts)
+{
+#if IS_ENABLED(CONFIG_MPTCP)
+	if (unlikely(OPTION_MPTCP & opts->options))
+		mptcp_write_options(ptr, &opts->mptcp);
+#endif
+}
+
 /* Write previously computed TCP options to the packet.
  *
  * Beware: Something in the Internet is very sensitive to the ordering of
@@ -549,6 +560,8 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 	}
 
 	smc_options_write(ptr, &options);
+
+	mptcp_options_write(ptr, opts);
 }
 
 static void smc_set_option(const struct tcp_sock *tp,
-- 
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