[MPTCP] [PATCH 6/7] mptcp: Check flags in MP_CAPABLE option

[Peter Krystad <peter.krystad at linux.intel.com>]

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squashto: Handle MPTCP TCP options

Signed-off-by: Peter Krystad <peter.krystad(a)linux.intel.com>
---
 net/mptcp/options.c  | 6 +++++-
 net/mptcp/protocol.h | 7 ++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index df4405d268f0..98d582207cb0 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -29,8 +29,12 @@ void mptcp_parse_option(const unsigned char *ptr, int opsize,
 		if (mp_opt->version != 0)
 			break;
 
-		mp_opt->mp_capable = 1;
 		mp_opt->flags = *ptr++;
+		if (!((mp_opt->flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA1) ||
+		    (mp_opt->flags & MPTCP_CAP_EXTENSIBILITY))
+			break;
+
+		mp_opt->mp_capable = 1;
 		mp_opt->sndr_key = get_unaligned_be64(ptr);
 		ptr += 8;
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 6498e68e1030..2c2f2ca4312b 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -23,9 +23,10 @@
 #define MPTCPOPT_VERSION_MASK	0x0F
 
 /* MPTCP handshake flags */
-#define MPTCP_CAP_CHECKSUM_REQD	(1 << 7)
-#define MPTCP_CAP_EXTENSIBILITY	(1 << 6)
-#define MPTCP_CAP_HMAC_SHA1	(1 << 0)
+#define MPTCP_CAP_CHECKSUM_REQD	BIT(7)
+#define MPTCP_CAP_EXTENSIBILITY	BIT(6)
+#define MPTCP_CAP_HMAC_SHA1	BIT(0)
+#define MPTCP_CAP_FLAG_MASK	(0x3F)
 
 /* MPTCP DSS flags */
 #define MPTCP_DSS_DATA_FIN	BIT(4)
-- 
2.17.2