From 490cc7d03c21871eef5949ba77a18b0c7ef70ef5 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Tue, 12 Aug 2014 15:08:12 -0400 Subject: [PATCH] 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: Eric Dumazet Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 8fcfc91964ec..ef4a051de018 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -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); -- GitLab