| Message ID | 20200204173019.4437-2-alex.aring@gmail.com |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | net: ipv6: seg6: headroom fixes | expand |
From: Alexander Aring <alex.aring@gmail.com> Date: Tue, 4 Feb 2020 12:30:18 -0500 > diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c > index ab7f124ff5d7..5b6e88f16e2d 100644 > --- a/net/ipv6/seg6_iptunnel.c > +++ b/net/ipv6/seg6_iptunnel.c > @@ -449,8 +449,6 @@ static int seg6_build_state(struct nlattr *nla, > if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP) > newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; > > - newts->headroom = seg6_lwt_headroom(tuninfo); > - > *ts = newts; > > return 0; Even if this change is correct, you are eliminating the one and only user of seg6_lwt_headroom() so you would have to kill that in this patch as well.
Hi, On Thu, Feb 06, 2020 at 01:54:18PM +0100, David Miller wrote: > From: Alexander Aring <alex.aring@gmail.com> > Date: Tue, 4 Feb 2020 12:30:18 -0500 > > > diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c > > index ab7f124ff5d7..5b6e88f16e2d 100644 > > --- a/net/ipv6/seg6_iptunnel.c > > +++ b/net/ipv6/seg6_iptunnel.c > > @@ -449,8 +449,6 @@ static int seg6_build_state(struct nlattr *nla, > > if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP) > > newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; > > > > - newts->headroom = seg6_lwt_headroom(tuninfo); > > - > > *ts = newts; > > > > return 0; > > Even if this change is correct, you are eliminating the one and only > user of seg6_lwt_headroom() so you would have to kill that in this > patch as well. Okay, this is in include/uapi but surrounding by __KERNEL__ so I guess it's still okay to remove it? btw: why it is not static in seg6_iptunnel.c then? Anyway I will wait until I hear something back what the use of headroom exactly is and why the original authors of segmentation routing sets it. In my case it will simple not work with a IPv6 min mtu so I will set it to zero for possible net-next patches. - Alex
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index ab7f124ff5d7..5b6e88f16e2d 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -449,8 +449,6 @@ static int seg6_build_state(struct nlattr *nla, if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP) newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT; - newts->headroom = seg6_lwt_headroom(tuninfo); - *ts = newts; return 0;
This patch sets headroom of segmentation route tunnel to zero. The headroom setting was introduced for mpls in commit 14972cbd34ff ("net: lwtunnel: Handle fragmentation") which sits on layer 2.5. As the Linux interface MTU value is Layer 3 and don't consider anything before that it is misleading to set the headroom value to anything than 0. Example setup to trigger this issue: ip netns add foo ip link add veth0 type veth peer name veth1 ip link set veth1 netns foo ip link set mtu 1280 dev veth0 ip link set veth0 up ip -n foo link set veth1 up ip addr add beef::1/64 dev veth0 ip -6 route add beef::3 encap seg6 mode encap segs beef::2 dev veth0 then do a: ping beef::3 You the sendmsg() will return -EINVAL because the packet doesn't fit into the IPv6 minimum MTU anymore. It was consider the headroom value in their destination mtu which substracts whatever headroom is from the interface MTU 1280. Signed-off-by: Alexander Aring <alex.aring@gmail.com> --- net/ipv6/seg6_iptunnel.c | 2 -- 1 file changed, 2 deletions(-)