netdev - [PATCH net-next] mptcp: attempt coalescing when moving skbs to mptcp rx queue

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 25 May 2020 23:41:13 +0200
From:   Florian Westphal <fw@...len.de>
To:     <netdev@...r.kernel.org>
Cc:     mathew.j.martineau@...ux.intel.com, pabeni@...hat.com,
        matthieu.baerts@...sares.net, Florian Westphal <fw@...len.de>
Subject: [PATCH net-next] mptcp: attempt coalescing when moving skbs to mptcp rx queue

We can try to coalesce skbs we take from the subflows rx queue with the
tail of the mptcp rx queue.

If successful, the skb head can be discarded early.

We can also free the skb extensions, we do not access them after this.

Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/mptcp/protocol.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d868b3d921fd..e07a5896fea4 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -144,12 +144,29 @@ static void __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
 			     unsigned int offset, size_t copy_len)
 {
 	struct sock *sk = (struct sock *)msk;
+	struct sk_buff *tail;
 
 	__skb_unlink(skb, &ssk->sk_receive_queue);
-	skb_set_owner_r(skb, sk);
-	__skb_queue_tail(&sk->sk_receive_queue, skb);
 
+	skb_ext_reset(skb);
+	skb_orphan(skb);
 	msk->ack_seq += copy_len;
+
+	tail = skb_peek_tail(&sk->sk_receive_queue);
+	if (offset == 0 && tail) {
+		bool fragstolen;
+		int delta;
+
+		if (skb_try_coalesce(tail, skb, &fragstolen, &delta)) {
+			kfree_skb_partial(skb, fragstolen);
+			atomic_add(delta, &sk->sk_rmem_alloc);
+			sk_mem_charge(sk, delta);
+			return;
+		}
+	}
+
+	skb_set_owner_r(skb, sk);
+	__skb_queue_tail(&sk->sk_receive_queue, skb);
 	MPTCP_SKB_CB(skb)->offset = offset;
 }
 
-- 
2.26.2