mptcp: Add path manager interface

Add enough of a path manager interface to allow sending of ADD_ADDR
when an incoming MPTCP connection is created. Capable of sending only
a single IPv4 ADD_ADDR option. The 'pm_data' element of the connection
sock will need to be expanded to handle multiple interfaces and IPv6.
Partial processing of the incoming ADD_ADDR is included so the path
manager notification of that event happens at the proper time, which
involves validating the incoming address information.

This is a skeleton interface definition for events generated by
MPTCP.

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: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 64 insertions, 16 deletions

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 6c6c18a09a40..a3661318a7af 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -492,36 +492,35 @@ static bool mptcp_established_options_addr(struct sock *sk,
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
-	struct sockaddr_storage saddr;
-	u8 id;
+	struct mptcp_addr_info saddr;
+	int len;
 
-	id = 0;
-	memset(&saddr, 0, sizeof(saddr));
+	if (!mptcp_pm_should_signal(msk) ||
+	    !(mptcp_pm_addr_signal(msk, remaining, &saddr)))
+		return false;
+
+	len = mptcp_add_addr_len(saddr.family);
+	if (remaining < len)
+		return false;
 
-	if (saddr.ss_family == AF_INET) {
-		if (remaining < TCPOLEN_MPTCP_ADD_ADDR)
-			return false;
+	*size = len;
+	opts->addr_id = saddr.id;
+	if (saddr.family == AF_INET) {
 		opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
-		opts->addr_id = id;
-		opts->addr = ((struct sockaddr_in *)&saddr)->sin_addr;
+		opts->addr = saddr.addr;
 		opts->ahmac = add_addr_generate_hmac(msk->local_key,
 						     msk->remote_key,
 						     opts->addr_id,
 						     &opts->addr);
-		*size = TCPOLEN_MPTCP_ADD_ADDR;
 	}
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
-	else if (saddr.ss_family == AF_INET6) {
-		if (remaining < TCPOLEN_MPTCP_ADD_ADDR6)
-			return false;
+	else if (saddr.family == AF_INET6) {
 		opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
-		opts->addr_id = id;
+		opts->addr6 = saddr.addr6;
 		opts->ahmac = add_addr6_generate_hmac(msk->local_key,
 						      msk->remote_key,
 						      opts->addr_id,
 						      &opts->addr6);
-		opts->addr6 = ((struct sockaddr_in6 *)&saddr)->sin6_addr;
-		*size = TCPOLEN_MPTCP_ADD_ADDR6;
 	}
 #endif
 	pr_debug("addr_id=%d, ahmac=%llu", opts->addr_id, opts->ahmac);
@@ -607,10 +606,37 @@ static bool check_fully_established(struct mptcp_subflow_context *subflow,
 	return true;
 }
 
+static bool add_addr_hmac_valid(struct mptcp_sock *msk,
+				struct mptcp_options_received *mp_opt)
+{
+	u64 hmac = 0;
+
+	if (mp_opt->echo)
+		return true;
+
+	if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
+		hmac = add_addr_generate_hmac(msk->remote_key,
+					      msk->local_key,
+					      mp_opt->addr_id, &mp_opt->addr);
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	else
+		hmac = add_addr6_generate_hmac(msk->remote_key,
+					       msk->local_key,
+					       mp_opt->addr_id, &mp_opt->addr6);
+#endif
+
+	pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
+		 msk, (unsigned long long)hmac,
+		 (unsigned long long)mp_opt->ahmac);
+
+	return hmac == mp_opt->ahmac;
+}
+
 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 			    struct tcp_options_received *opt_rx)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 	struct mptcp_options_received *mp_opt;
 	struct mptcp_ext *mpext;
 
@@ -618,6 +644,26 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 	if (!check_fully_established(subflow, skb, mp_opt))
 		return;
 
+	if (mp_opt->add_addr && add_addr_hmac_valid(msk, mp_opt)) {
+		struct mptcp_addr_info addr;
+
+		addr.port = htons(mp_opt->port);
+		addr.id = mp_opt->addr_id;
+		if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
+			addr.family = AF_INET;
+			addr.addr = mp_opt->addr;
+		}
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+		else if (mp_opt->family == MPTCP_ADDR_IPVERSION_6) {
+			addr.family = AF_INET6;
+			addr.addr6 = mp_opt->addr6;
+		}
+#endif
+		if (!mp_opt->echo)
+			mptcp_pm_add_addr_received(msk, &addr);
+		mp_opt->add_addr = 0;
+	}
+
 	if (!mp_opt->dss)
 		return;
 
@@ -654,6 +700,8 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
 	}
 
 	mpext->data_fin = mp_opt->data_fin;
+
+	mptcp_pm_fully_established(msk);
 }
 
 void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)