Message ID | 1480532468-1610-1-git-send-email-soheil.kdev@gmail.com |
---|---|
State | Accepted, archived |
Delegated to: | David Miller |
Headers | show |
On Wed, 2016-11-30 at 14:01 -0500, Soheil Hassas Yeganeh wrote: > From: Soheil Hassas Yeganeh <soheil@google.com> > > Only when ICMP packets are enqueued onto the error queue, > sk_err is also set. Before f5f99309fa74 (sock: do not set sk_err > in sock_dequeue_err_skb), a subsequent error queue read > would set sk_err to the next error on the queue, or 0 if empty. > As no error types other than ICMP set this field, sk_err should > not be modified upon dequeuing them. > > Only for ICMP errors, reset the (racy) sk_err. Some applications, > like traceroute, rely on it and go into a futile busy POLLERR > loop otherwise. > > In principle, sk_err has to be set while an ICMP error is queued. > Testing is_icmp_err_skb(skb_next) approximates this without > requiring a full queue walk. Applications that receive both ICMP > and other errors cannot rely on this legacy behavior, as other > errors do not set sk_err in the first place. > > Fixes: f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb) > Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> > Signed-off-by: Willem de Bruijn <willemb@google.com> > --- Acked-by: Eric Dumazet <edumazet@google.com>
On Wed, Nov 30, 2016 at 8:01 PM, Soheil Hassas Yeganeh <soheil.kdev@gmail.com> wrote: > From: Soheil Hassas Yeganeh <soheil@google.com> > > Only when ICMP packets are enqueued onto the error queue, > sk_err is also set. Before f5f99309fa74 (sock: do not set sk_err > in sock_dequeue_err_skb), a subsequent error queue read > would set sk_err to the next error on the queue, or 0 if empty. > As no error types other than ICMP set this field, sk_err should > not be modified upon dequeuing them. > > Only for ICMP errors, reset the (racy) sk_err. Some applications, > like traceroute, rely on it and go into a futile busy POLLERR > loop otherwise. > > In principle, sk_err has to be set while an ICMP error is queued. > Testing is_icmp_err_skb(skb_next) approximates this without > requiring a full queue walk. Applications that receive both ICMP > and other errors cannot rely on this legacy behavior, as other > errors do not set sk_err in the first place. > > Fixes: f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb) > Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> > Signed-off-by: Willem de Bruijn <willemb@google.com> Acked-by: Maciej Żenczykowski <maze@google.com>
From: Soheil Hassas Yeganeh <soheil.kdev@gmail.com> Date: Wed, 30 Nov 2016 14:01:08 -0500 > From: Soheil Hassas Yeganeh <soheil@google.com> > > Only when ICMP packets are enqueued onto the error queue, > sk_err is also set. Before f5f99309fa74 (sock: do not set sk_err > in sock_dequeue_err_skb), a subsequent error queue read > would set sk_err to the next error on the queue, or 0 if empty. > As no error types other than ICMP set this field, sk_err should > not be modified upon dequeuing them. > > Only for ICMP errors, reset the (racy) sk_err. Some applications, > like traceroute, rely on it and go into a futile busy POLLERR > loop otherwise. > > In principle, sk_err has to be set while an ICMP error is queued. > Testing is_icmp_err_skb(skb_next) approximates this without > requiring a full queue walk. Applications that receive both ICMP > and other errors cannot rely on this legacy behavior, as other > errors do not set sk_err in the first place. > > Fixes: f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb) > Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> > Signed-off-by: Willem de Bruijn <willemb@google.com> Applied, thanks.
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index d1d1a5a..8dad391 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3714,20 +3714,29 @@ int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(sock_queue_err_skb); +static bool is_icmp_err_skb(const struct sk_buff *skb) +{ + return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP || + SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6); +} + struct sk_buff *sock_dequeue_err_skb(struct sock *sk) { struct sk_buff_head *q = &sk->sk_error_queue; - struct sk_buff *skb, *skb_next; + struct sk_buff *skb, *skb_next = NULL; + bool icmp_next = false; unsigned long flags; - int err = 0; spin_lock_irqsave(&q->lock, flags); skb = __skb_dequeue(q); if (skb && (skb_next = skb_peek(q))) - err = SKB_EXT_ERR(skb_next)->ee.ee_errno; + icmp_next = is_icmp_err_skb(skb_next); spin_unlock_irqrestore(&q->lock, flags); - if (err) + if (is_icmp_err_skb(skb) && !icmp_next) + sk->sk_err = 0; + + if (skb_next) sk->sk_error_report(sk); return skb;