Hi Herbert,
On Fri, 15 Feb 2008, Herbert Xu wrote:
> On Tue, Feb 12, 2008 at 06:08:28PM -0800, David Miller wrote:
> >
> > > [IPV6]: Fix IPsec datagram fragmentation
> >
> > Applied, and I'll queue this up to -stable as well.
>
> Sorry, David Stevens just told me that it doesn't work as intended.
>
> [IPV6]: Fix reversed local_df test in ip6_fragment
>
> I managed to reverse the local_df test when forward-porting this
> patch so it actually makes things worse by never fragmenting at
> all.
>
> Thanks to David Stevens for testing and reporting this bug.
>
> Signed-off-by: Herbert Xu <[EMAIL PROTECTED]>
>
> --
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 4e9a2fe..35ba693 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -621,7 +621,7 @@ static int ip6_fragment(struct sk_buff *skb, int
> (*output)(struct sk_buff *))
> * or if the skb it not generated by a local socket. (This last
> * check should be redundant, but it's free.)
> */
> - if (skb->local_df) {
> + if (!skb->local_df) {
> skb->dev = skb->dst->dev;
> icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
> IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
I think the setting of skb->local_def is still backwards in your
original patch:
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 9ac6ca2..4e9a2fe 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
...
> @@ -1420,6 +1420,10 @@ int ip6_push_pending_frames(struct sock *sk)
> tmp_skb->sk = NULL;
> }
>
> + /* Allow local fragmentation. */
> + if (np->pmtudisc >= IPV6_PMTUDISC_DO)
> + skb->local_df = 1;
> +
> ipv6_addr_copy(final_dst, &fl->fl6_dst);
> __skb_pull(skb, skb_network_header_len(skb));
> if (opt && opt->opt_flen)
I think the test should be:
if (np->pmtudisc < IPV6_PMTUDISC_DO)
as it is in net/ipv4/ip_output.c:
/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
* to fragment the frame generated here. No matter, what transforms
* how transforms change size of the packet, it will come out.
*/
if (inet->pmtudisc < IP_PMTUDISC_DO)
skb->local_df = 1;
Or perhaps I'm just missing something obvious.
-Bill
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