On 12/12/2017 5:53 AM, Alexey Kodanev wrote:
LTP/udp6_ipsec_vti tests fail when sending large UDP datagrams that require fragmentation and the underlying device has MTU <= 1500. This happens because ip6_vti sets mtu to ETH_DATA_LEN and not updating it depending on a destination address or link parameter.Further attempts to send UDP packets may succeed because pmtu gets updated on ICMPV6_PKT_TOOBIG in vti6_err(). Here is the example when the output device MTU is set to 9000: # ip a sh ltp_ns_veth2 ltp_ns_veth2@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 ... inet 10.0.0.2/24 scope global ltp_ns_veth2 inet6 fd00::2/64 scope global # ip li add vti6 type vti6 local fd00::2 remote fd00::1 # ip li show vti6 vti6@NONE: <POINTOPOINT,NOARP> mtu 1500 ... link/tunnel6 fd00::2 peer fd00::1 After the patch: # ip li add vti6 type vti6 local fd00::2 remote fd00::1 # ip li show vti6 vti6@NONE: <POINTOPOINT,NOARP> mtu 8832 ... link/tunnel6 fd00::2 peer fd00::1 Regarding ip_vti, it already tunes MTU with ip_tunnel_bind_dev(). Reported-by: Petr Vorel <pvo...@suse.cz> Signed-off-by: Alexey Kodanev <alexey.koda...@oracle.com> --- v2: * cleanup commit message issues (thanks to Shannon)
Acked-by: Shannon Nelson <shannon.nel...@oracle.com>
* handle the case when we don't have route but have device parameter * cast new MTU to int and then check the maximum (tdev->mtu can be less than dev->hard_header_len) When changing the tunnel parameters, MTU can be updated as well... should we also check that parms 'link', 'laddr' or 'raddr' were actually changed in vti6_tnl_change() and/or IFLA_MTU wasn't set? net/ipv6/ip6_vti.c | 22 ++++++++++++++++++++++ 1 files changed, 22 insertions(+), 0 deletions(-) diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index dbb74f3..d4624c2 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -626,6 +626,7 @@ static void vti6_link_config(struct ip6_tnl *t) { struct net_device *dev = t->dev; struct __ip6_tnl_parm *p = &t->parms; + struct net_device *tdev = NULL;memcpy(dev->dev_addr, &p->laddr, sizeof(struct in6_addr));memcpy(dev->broadcast, &p->raddr, sizeof(struct in6_addr)); @@ -638,6 +639,27 @@ static void vti6_link_config(struct ip6_tnl *t) dev->flags |= IFF_POINTOPOINT; else dev->flags &= ~IFF_POINTOPOINT; + + if (p->flags & IP6_TNL_F_CAP_XMIT) { + int strict = (ipv6_addr_type(&p->raddr) & + (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL)); + + struct rt6_info *rt = rt6_lookup(t->net, + &p->raddr, &p->laddr, + p->link, strict); + + if (rt) + tdev = rt->dst.dev; + ip6_rt_put(rt); + } + + if (!tdev && p->link) + tdev = __dev_get_by_index(t->net, p->link); + + if (tdev) { + dev->mtu = max_t(int, tdev->mtu - dev->hard_header_len, + IPV6_MIN_MTU); + } }/**
