diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-02-13 04:47:12 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-02-13 07:11:40 -0800 |
| commit | ba34e6d9d346fe4e05d7e417b9edf5140772d34c (patch) | |
| tree | c0470809aa6a3e92fce6c0b37757ab58e75e9dc5 /net/ipv4 | |
| parent | 9672723973f1e70189b8409eb2da189a980481c5 (diff) | |
tcp: make sure skb is not shared before using skb_get()
IPv6 can keep a copy of SYN message using skb_get() in
tcp_v6_conn_request() so that caller wont free the skb when calling
kfree_skb() later.
Therefore TCP fast open has to clone the skb it is queuing in
child->sk_receive_queue, as all skbs consumed from receive_queue are
freed using __kfree_skb() (ie assuming skb->users == 1)
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Fixes: 5b7ed0892f2af ("tcp: move fastopen functions to tcp_fastopen.c")
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_fastopen.c | 32 |
1 files changed, 24 insertions, 8 deletions
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index 53db2c309572..ea82fd492c1b 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -134,6 +134,7 @@ static bool tcp_fastopen_create_child(struct sock *sk, struct tcp_sock *tp; struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; struct sock *child; + u32 end_seq; req->num_retrans = 0; req->num_timeout = 0; @@ -185,20 +186,35 @@ static bool tcp_fastopen_create_child(struct sock *sk, /* Queue the data carried in the SYN packet. We need to first * bump skb's refcnt because the caller will attempt to free it. + * Note that IPv6 might also have used skb_get() trick + * in tcp_v6_conn_request() to keep this SYN around (treq->pktopts) + * So we need to eventually get a clone of the packet, + * before inserting it in sk_receive_queue. * * XXX (TFO) - we honor a zero-payload TFO request for now, * (any reason not to?) but no need to queue the skb since * there is no data. How about SYN+FIN? */ - if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1) { - skb = skb_get(skb); - skb_dst_drop(skb); - __skb_pull(skb, tcp_hdr(skb)->doff * 4); - skb_set_owner_r(skb, child); - __skb_queue_tail(&child->sk_receive_queue, skb); - tp->syn_data_acked = 1; + end_seq = TCP_SKB_CB(skb)->end_seq; + if (end_seq != TCP_SKB_CB(skb)->seq + 1) { + struct sk_buff *skb2; + + if (unlikely(skb_shared(skb))) + skb2 = skb_clone(skb, GFP_ATOMIC); + else + skb2 = skb_get(skb); + + if (likely(skb2)) { + skb_dst_drop(skb2); + __skb_pull(skb2, tcp_hdrlen(skb)); + skb_set_owner_r(skb2, child); + __skb_queue_tail(&child->sk_receive_queue, skb2); + tp->syn_data_acked = 1; + } else { + end_seq = TCP_SKB_CB(skb)->seq + 1; + } } - tcp_rsk(req)->rcv_nxt = tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; + tcp_rsk(req)->rcv_nxt = tp->rcv_nxt = end_seq; sk->sk_data_ready(sk); bh_unlock_sock(child); sock_put(child); |