On Tue, 2017-12-19 at 12:58 -0800, Shaohua Li wrote: > From: Shaohua Li <[email protected]> > > ipv6_pinfo.autoflowlabel is set in sock creation. Later if we change > sysctl.ip6.auto_flowlabels, the ipv6_pinfo.autoflowlabel isn't changed, > so the sock will keep the old behavior in terms of auto flowlabel. Reset > packet is suffering from this problem, because reset packset is sent > from a special control socket, which is created at boot time. Since > sysctl.ipv6.auto_flowlabels is 2 by default, the control socket will > always have its ipv6_pinfo.autoflowlabel set, even after user set > sysctl.ipv6.auto_flowlabels to 1, so reset packset will always have > flowlabel. > > To fix this, we always reevaluate autoflowlabel setting for reset > packet. Normal sock has the same issue too, but since the > sysctl.ipv6.auto_flowlabels is usually set at host startup, this isn't a > big issue for normal sock. > > Cc: Martin KaFai Lau <[email protected]> > Signed-off-by: Shaohua Li <[email protected]> > --- > net/ipv6/tcp_ipv6.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c > index 7178476..5fba548 100644 > --- a/net/ipv6/tcp_ipv6.c > +++ b/net/ipv6/tcp_ipv6.c > @@ -787,9 +787,11 @@ static void tcp_v6_send_response(const struct sock *sk, > struct sk_buff *skb, u32 > struct net *net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev); > struct sock *ctl_sk = net->ipv6.tcp_sk; > unsigned int tot_len = sizeof(struct tcphdr); > + struct ipv6_pinfo *np = inet6_sk(ctl_sk); > struct dst_entry *dst; > __be32 *topt; > > + np->autoflowlabel = ip6_default_np_autolabel(net);
This looks unsafe to set a bitfield on a shared socket (one ctl_sk per netns) Compiler could play strange things here.
