diff mbox series

[net-next,09/10] mptcp: track window announced to peer

Message ID 20201119194603.103158-10-mathew.j.martineau@linux.intel.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series mptcp: More miscellaneous MPTCP fixes | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1509 this patch: 1509
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 124 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 1516 this patch: 1516
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Mat Martineau Nov. 19, 2020, 7:46 p.m. UTC 
From: Florian Westphal <fw@strlen.de>

OoO handling attempts to detect when packet is out-of-window by testing
current ack sequence and remaining space vs. sequence number.

This doesn't work reliably. Store the highest allowed sequence number
that we've announced and use it to detect oow packets.

Do this when mptcp options get written to the packet (wire format).
For this to work we need to move the write_options call until after
stack selected a new tcp window.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 include/net/mptcp.h   |  3 ++-
 net/ipv4/tcp_output.c | 11 +++++++----
 net/mptcp/options.c   | 22 +++++++++++++++++++++-
 net/mptcp/protocol.c  | 12 +++++++-----
 net/mptcp/protocol.h  |  1 +
 5 files changed, 38 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 6e706d838e4e..b6cf07143a8a 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -88,7 +88,8 @@  bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 			       struct mptcp_out_options *opts);
 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb);
 
-void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts);
+void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
+			 struct mptcp_out_options *opts);
 
 /* move the skb extension owership, with the assumption that 'to' is
  * newly allocated
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 99905bc01d40..41880d3521ed 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -445,11 +445,12 @@  struct tcp_out_options {
 	struct mptcp_out_options mptcp;
 };
 
-static void mptcp_options_write(__be32 *ptr, struct tcp_out_options *opts)
+static void mptcp_options_write(__be32 *ptr, const struct tcp_sock *tp,
+				struct tcp_out_options *opts)
 {
 #if IS_ENABLED(CONFIG_MPTCP)
 	if (unlikely(OPTION_MPTCP & opts->options))
-		mptcp_write_options(ptr, &opts->mptcp);
+		mptcp_write_options(ptr, tp, &opts->mptcp);
 #endif
 }
 
@@ -701,7 +702,7 @@  static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 
 	smc_options_write(ptr, &options);
 
-	mptcp_options_write(ptr, opts);
+	mptcp_options_write(ptr, tp, opts);
 }
 
 static void smc_set_option(const struct tcp_sock *tp,
@@ -1346,7 +1347,6 @@  static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 		}
 	}
 
-	tcp_options_write((__be32 *)(th + 1), tp, &opts);
 	skb_shinfo(skb)->gso_type = sk->sk_gso_type;
 	if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) {
 		th->window      = htons(tcp_select_window(sk));
@@ -1357,6 +1357,9 @@  static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 		 */
 		th->window	= htons(min(tp->rcv_wnd, 65535U));
 	}
+
+	tcp_options_write((__be32 *)(th + 1), tp, &opts);
+
 #ifdef CONFIG_TCP_MD5SIG
 	/* Calculate the MD5 hash, as we have all we need now */
 	if (md5) {
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index d7afffcc87c1..248e3930c0cb 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1010,7 +1010,24 @@  void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 	}
 }
 
-void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
+static void mptcp_set_rwin(const struct tcp_sock *tp)
+{
+	const struct sock *ssk = (const struct sock *)tp;
+	const struct mptcp_subflow_context *subflow;
+	struct mptcp_sock *msk;
+	u64 ack_seq;
+
+	subflow = mptcp_subflow_ctx(ssk);
+	msk = mptcp_sk(subflow->conn);
+
+	ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
+
+	if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
+		WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
+}
+
+void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
+			 struct mptcp_out_options *opts)
 {
 	if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
 	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
@@ -1167,4 +1184,7 @@  void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
 					   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
 		}
 	}
+
+	if (tp)
+		mptcp_set_rwin(tp);
 }
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index c2629190b1ce..4ae2c4a30e44 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -168,19 +168,19 @@  static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)
 	struct rb_node **p, *parent;
 	u64 seq, end_seq, max_seq;
 	struct sk_buff *skb1;
-	int space;
 
 	seq = MPTCP_SKB_CB(skb)->map_seq;
 	end_seq = MPTCP_SKB_CB(skb)->end_seq;
-	space = tcp_space(sk);
-	max_seq = space > 0 ? space + msk->ack_seq : msk->ack_seq;
+	max_seq = READ_ONCE(msk->rcv_wnd_sent);
 
 	pr_debug("msk=%p seq=%llx limit=%llx empty=%d", msk, seq, max_seq,
 		 RB_EMPTY_ROOT(&msk->out_of_order_queue));
-	if (after64(seq, max_seq)) {
+	if (after64(end_seq, max_seq)) {
 		/* out of window */
 		mptcp_drop(sk, skb);
-		pr_debug("oow by %ld", (unsigned long)seq - (unsigned long)max_seq);
+		pr_debug("oow by %lld, rcv_wnd_sent %llu\n",
+			 (unsigned long long)end_seq - (unsigned long)max_seq,
+			 (unsigned long long)msk->rcv_wnd_sent);
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW);
 		return;
 	}
@@ -2294,6 +2294,7 @@  struct sock *mptcp_sk_clone(const struct sock *sk,
 		mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);
 		ack_seq++;
 		WRITE_ONCE(msk->ack_seq, ack_seq);
+		WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
 	}
 
 	sock_reset_flag(nsk, SOCK_RCU_FREE);
@@ -2586,6 +2587,7 @@  void mptcp_finish_connect(struct sock *ssk)
 	WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
 	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
 	WRITE_ONCE(msk->ack_seq, ack_seq);
+	WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
 	WRITE_ONCE(msk->can_ack, 1);
 	atomic64_set(&msk->snd_una, msk->write_seq);
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 4d6dd4adaaaf..67f86818203f 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -216,6 +216,7 @@  struct mptcp_sock {
 	u64		write_seq;
 	u64		snd_nxt;
 	u64		ack_seq;
+	u64		rcv_wnd_sent;
 	u64		rcv_data_fin_seq;
 	struct sock	*last_snd;
 	int		snd_burst;