Commit 490cc7d0 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

net-timestamp: fix missing tcp fragmentation cases 



Bytestream timestamps are correlated with a single byte in the skbuff,
recorded in skb_shinfo(skb)->tskey. When fragmenting skbuffs, ensure
that the tskey is set for the fragment in which the tskey falls
(seqno <= tskey < end_seqno).

The original implementation did not address fragmentation in
tcp_fragment or tso_fragment. Add code to inspect the sequence numbers
and move both tskey and the relevant tx_flags if necessary.

Reported-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 712a7221

net/ipv4/tcp_output.c

+17 −0
Original line number Diff line number Diff line
@@ -1069,6 +1069,21 @@ static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int de 
	tcp_verify_left_out(tp);

}



static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2)

{

	struct skb_shared_info *shinfo = skb_shinfo(skb);



	if (unlikely(shinfo->tx_flags & SKBTX_ANY_TSTAMP) &&

	    !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) {

		struct skb_shared_info *shinfo2 = skb_shinfo(skb2);

		u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP;



		shinfo->tx_flags &= ~tsflags;

		shinfo2->tx_flags |= tsflags;

		swap(shinfo->tskey, shinfo2->tskey);

	}

}



/* Function to create two new TCP segments.  Shrinks the given segment

 * to the specified size and appends a new segment with the rest of the

 * packet to the list.  This won't be called frequently, I hope.
@@ -1136,6 +1151,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, 
	 */

	TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when;

	buff->tstamp = skb->tstamp;

	tcp_fragment_tstamp(skb, buff);



	old_factor = tcp_skb_pcount(skb);
@@ -1652,6 +1668,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 


	buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL;

	skb_split(skb, buff, len);

	tcp_fragment_tstamp(skb, buff);



	/* Fix up tso_factor for both original and new SKB.  */

	tcp_set_skb_tso_segs(sk, skb, mss_now);

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