[MPTCP] [RFC PATCH v5 04/17] mptcp: Handle MPTCP TCP options

[MPTCP] [RFC PATCH v5 04/17] mptcp: Handle MPTCP TCP options

[Mat Martineau]

[-- Attachment #1: Type: text/plain, Size: 11696 bytes --]

From: Peter Krystad <peter.krystad(a)intel.com>

Signed-off-by: Peter Krystad <peter.krystad(a)intel.com>
---
 include/linux/tcp.h   |  11 +++
 include/net/mptcp.h   |  35 ++++++++++
 include/net/tcp.h     |   2 +
 net/ipv4/tcp_input.c  |   5 ++
 net/ipv4/tcp_output.c |  69 +++++++++++++++----
 net/mptcp/Makefile    |   2 +-
 net/mptcp/options.c   | 151 ++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 262 insertions(+), 13 deletions(-)
 create mode 100644 net/mptcp/options.c

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index a9b0280687d5..5778de6b6277 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -104,6 +104,16 @@ struct tcp_options_received {
 	u8	num_sacks;	/* Number of SACK blocks		*/
 	u16	user_mss;	/* mss requested by user in ioctl	*/
 	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */
+	struct {
+		u8      mp_capable : 1,
+			mp_join : 1,
+			dss : 1,
+			version : 4;
+		u8      flags;
+		u64     sndr_key;
+		u64     rcvr_key;
+	} mptcp;
+
 };
 
 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
@@ -113,6 +123,7 @@ static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 #if IS_ENABLED(CONFIG_SMC)
 	rx_opt->smc_ok = 0;
 #endif
+	rx_opt->mptcp.mp_capable = rx_opt->mptcp.mp_join = rx_opt->mptcp.dss = 0;
 }
 
 /* This is the max number of SACKS that we'll generate and process. It's safe
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 7f7b18b000fe..f88213e31fbe 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -18,6 +18,23 @@
 
 #include <linux/tcp.h>
 
+/* MPTCP option subtypes */
+
+#define MPTCPOPT_MP_CAPABLE	0
+#define MPTCPOPT_MP_JOIN	1
+#define MPTCPOPT_DSS		2
+#define MPTCPOPT_ADD_ADDR	3
+#define MPTCPOPT_REMOVE_ADDR	4
+#define MPTCPOPT_MP_PRIO	5
+#define MPTCPOPT_MP_FAIL	6
+#define MPTCPOPT_MP_FASTCLOSE	7
+
+/* MPTCP handshake flags */
+
+#define MPTCP_CAP_CHECKSUM_REQD	(1 << 7)
+#define MPTCP_CAP_EXTENSIBILITY	(1 << 6)
+#define MPTCP_CAP_HMAC_SHA1	(1 << 0)
+
 /* MPTCP connection sock */
 struct mptcp_sock {
 	/* inet_connection_sock must be the first member */
@@ -30,4 +47,22 @@ static inline struct mptcp_sock *mptcp_sk(const struct sock *sk)
 	return (struct mptcp_sock *)sk;
 }
 
+#ifdef CONFIG_MPTCP
+
+void mptcp_parse_option(const unsigned char *ptr, int opsize,
+			struct tcp_options_received *opt_rx);
+
+void mptcp_get_options(const struct sk_buff *skb,
+		       struct tcp_options_received *options);
+
+#else
+
+static inline void mptcp_parse_option(const unsigned char *ptr, int opsize,
+				      struct tcp_options_received *opt_rx)
+{
+}
+
+
+
+#endif /* CONFIG_MPTCP */
 #endif /* __NET_MPTCP_H */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 39362f71319b..cf23ae77b77f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -215,6 +215,8 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCPOLEN_MD5SIG_ALIGNED		20
 #define TCPOLEN_MSS_ALIGNED		4
 #define TCPOLEN_EXP_SMC_BASE_ALIGNED	8
+#define TCPOLEN_MPTCP_MPC_SYN		12
+#define TCPOLEN_MPTCP_MPC_SYNACK	20
 
 /* Flags in tp->nonagle */
 #define TCP_NAGLE_OFF		1	/* Nagle's algo is disabled */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 76858b14ebe9..3a615109d0f4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -79,6 +79,7 @@
 #include <trace/events/tcp.h>
 #include <linux/static_key.h>
 #include <net/busy_poll.h>
+#include <net/mptcp.h>
 
 int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 
@@ -3858,6 +3859,10 @@ 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 730bc44dbad9..1fbccb931b93 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -37,6 +37,7 @@
 #define pr_fmt(fmt) "TCP: " fmt
 
 #include <net/tcp.h>
+#include <net/mptcp.h>
 
 #include <linux/compiler.h>
 #include <linux/gfp.h>
@@ -411,6 +412,60 @@ 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)
+
+/* MPTCP option subtypes */
+#define OPTION_MPTCP_MPC_SYN	(1 << 0)
+#define OPTION_MPTCP_MPC_SYNACK	(1 << 1)
+#define OPTION_MPTCP_MPC_ACK	(1 << 2)
+
+struct tcp_out_options {
+	u16 options;		/* bit field of OPTION_* */
+	u16 mss;		/* 0 to disable */
+	u8 ws;			/* window scale, 0 to disable */
+	u8 num_sack_blocks;	/* number of SACK blocks to include */
+	u8 hash_size;		/* bytes in hash_location */
+	__u8 *hash_location;	/* temporary pointer, overloaded */
+	__u32 tsval, tsecr;	/* need to include OPTION_TS */
+	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
+	u16 suboptions;         /* MPTCP sub-options */
+	u64 sndr_key;
+	u64 rcvr_key;
+};
+
+static void mptcp_options_write(__be32 *ptr, struct tcp_out_options *opts)
+{
+#if IS_ENABLED(CONFIG_MPTCP)
+	if (!(OPTION_MPTCP & opts->options))
+		return;
+
+	if ((OPTION_MPTCP_MPC_SYN |
+	     OPTION_MPTCP_MPC_SYNACK |
+	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
+		u8 len;
+		__be64 key;
+
+		if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
+			len = TCPOLEN_MPTCP_MPC_SYN;
+		else
+			len = TCPOLEN_MPTCP_MPC_SYNACK;
+
+		*ptr++ = htonl((0x1e << 24) | // TCP option: Multipath TCP
+			       (len << 16)  | // length
+			       (0 <<  8)    | // subtype=MP_CAPABLE | version=0
+			       (0x1));        // flags=HMAC-SHA1
+		key = cpu_to_be64(opts->sndr_key);
+		memcpy((u8 *) ptr, (u8 *) &key, 8);
+		ptr += 2;
+		if ((OPTION_MPTCP_MPC_SYNACK |
+		     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
+			key = cpu_to_be64(opts->rcvr_key);
+			memcpy((u8 *) ptr, (u8 *) &key, 8);
+			ptr += 2;
+		}
+	}
+#endif
+}
 
 static void smc_options_write(__be32 *ptr, u16 *options)
 {
@@ -427,17 +482,6 @@ static void smc_options_write(__be32 *ptr, u16 *options)
 #endif
 }
 
-struct tcp_out_options {
-	u16 options;		/* bit field of OPTION_* */
-	u16 mss;		/* 0 to disable */
-	u8 ws;			/* window scale, 0 to disable */
-	u8 num_sack_blocks;	/* number of SACK blocks to include */
-	u8 hash_size;		/* bytes in hash_location */
-	__u8 *hash_location;	/* temporary pointer, overloaded */
-	__u32 tsval, tsecr;	/* need to include OPTION_TS */
-	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
-};
-
 /* Write previously computed TCP options to the packet.
  *
  * Beware: Something in the Internet is very sensitive to the ordering of
@@ -546,6 +590,8 @@ 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,
@@ -710,7 +756,6 @@ static unsigned int tcp_synack_options(const struct sock *sk,
 			remaining -= need;
 		}
 	}
-
 	smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining);
 
 	return MAX_TCP_OPTION_SPACE - remaining;
diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
index 5624e7d51d48..2bd18e3b9fda 100644
--- a/net/mptcp/Makefile
+++ b/net/mptcp/Makefile
@@ -1,3 +1,3 @@
 obj-$(CONFIG_MPTCP) += mptcp.o
 
-mptcp-y := protocol.o
+mptcp-y := protocol.o options.o
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
new file mode 100644
index 000000000000..6e0a1ec56658
--- /dev/null
+++ b/net/mptcp/options.c
@@ -0,0 +1,151 @@
+/*
+ * Multipath TCP
+ *
+ * Copyright (c) 2017, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/kernel.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+
+void mptcp_parse_option(const unsigned char *ptr, int opsize,
+			struct tcp_options_received *opt_rx)
+{
+	u8 subtype;
+
+	opsize -= 2;
+	subtype = *ptr++;
+
+	/* MPTCPOPT_MP_CAPABLE
+	 * 0: 4MSB=subtype, 4LSB=version
+	 * 1: Handshake flags
+	 * 2-9: Sender key
+	 * 10-17: Receiver key (optional)
+	 */
+	switch (subtype & 0xF0) {
+	case 0x00:
+		pr_debug("MP_CAPABLE");
+		pr_debug("flags=%02x", *ptr);
+		opt_rx->mptcp.mp_capable = 1;
+		opt_rx->mptcp.version = subtype & 0x0F;
+		opt_rx->mptcp.flags = *ptr++;
+		opt_rx->mptcp.sndr_key = get_unaligned_be64(ptr);
+		pr_debug("sndr_key=%llu", opt_rx->mptcp.sndr_key);
+		ptr += 8;
+		if (opsize > TCPOLEN_MPTCP_MPC_SYN) {
+			opt_rx->mptcp.rcvr_key = get_unaligned_be64(ptr);
+			pr_debug("rcvr_key=%llu", opt_rx->mptcp.rcvr_key);
+			ptr += 8;
+		}
+		break;
+
+	/* MPTCPOPT_MP_JOIN
+	 *
+	 * Initial SYN
+	 * 0: 4MSB=subtype, 000, 1LSB=Backup
+	 * 1: Address ID
+	 * 2-5: Receiver token
+	 * 6-9: Sender random number
+	 *
+	 * SYN/ACK response
+	 * 0: 4MSB=subtype, 000, 1LSB=Backup
+	 * 1: Address ID
+	 * 2-9: Sender truncated HMAC
+	 * 10-13: Sender random number
+	 *
+	 * Third ACK
+	 * 0: 4MSB=subtype, 0000
+	 * 1: 0 (Reserved)
+	 * 2-21: Sender HMAC
+	 */
+
+	/* MPTCPOPT_DSS
+	 * 0: 4MSB=subtype, 0000
+	 * 1: 3MSB=0, F=Data FIN, m=DSN length, M=has DSN/SSN/DLL/checksum,
+	 *    a=DACK length, A=has DACK
+	 * 0, 4, or 8 bytes of DACK (depending on A/a)
+	 * 0, 4, or 8 bytes of DSN (depending on M/m)
+	 * 0 or 4 bytes of SSN (depending on M)
+	 * 0 or 2 bytes of DLL (depending on M)
+	 * 0 or 2 bytes of checksum (depending on M)
+	 */
+	case 0x20:
+		pr_debug("DSS");
+		opt_rx->mptcp.dss = 1;
+		break;
+
+	/* MPTCPOPT_ADD_ADDR
+	 * 0: 4MSB=subtype, 4LSB=IP version (4 or 6)
+	 * 1: Address ID
+	 * 4 or 16 bytes of address (depending on ip version)
+	 * 0 or 2 bytes of port (depending on length)
+	 */
+
+	/* MPTCPOPT_REMOVE_ADDR
+	 * 0: 4MSB=subtype, 0000
+	 * 1: Address ID
+	 * Additional bytes: More address IDs (depending on length)
+	 */
+
+	/* MPTCPOPT_MP_PRIO
+	 * 0: 4MSB=subtype, 000, 1LSB=Backup
+	 * 1: Address ID (optional, current addr implied if not present)
+	 */
+
+	/* MPTCPOPT_MP_FAIL
+	 * 0: 4MSB=subtype, 0000
+	 * 1: 0 (Reserved)
+	 * 2-9: DSN
+	 */
+
+	/* MPTCPOPT_MP_FASTCLOSE
+	 * 0: 4MSB=subtype, 0000
+	 * 1: 0 (Reserved)
+	 * 2-9: Receiver key
+	 */
+	default:
+		break;
+	}
+}
+
+void mptcp_get_options(const struct sk_buff *skb,
+		       struct tcp_options_received *opt_rx)
+{
+	const unsigned char *ptr;
+	const struct tcphdr *th = tcp_hdr(skb);
+	int length = (th->doff * 4) - sizeof(struct tcphdr);
+
+	ptr = (const unsigned char *)(th + 1);
+
+	while (length > 0) {
+		int opcode = *ptr++;
+		int opsize;
+
+		switch (opcode) {
+		case TCPOPT_EOL:
+			return;
+		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
+			length--;
+			continue;
+		default:
+			opsize = *ptr++;
+			if (opsize < 2) /* "silly options" */
+				return;
+			if (opsize > length)
+				return;	/* don't parse partial options */
+			if (opcode == TCPOPT_MPTCP)
+				mptcp_parse_option(ptr, opsize, opt_rx);
+			ptr += opsize - 2;
+			length -= opsize;
+		}
+	}
+}
-- 
2.20.0