path: root/net/ipv6/ip6_vti.c
diff options
authorAlexey Kodanev <alexey.kodanev@oracle.com>2017-12-19 16:59:21 +0300
committerDavid S. Miller <davem@davemloft.net>2017-12-20 11:52:32 -0500
commit53c81e95df1793933f87748d36070a721f6cb287 (patch)
treefa4eeff021ca22584a0f8aeba99312b7af584f5a /net/ipv6/ip6_vti.c
parentMerge branch 'nfp-flower-add-Geneve-tunnel-support' (diff)
ip6_vti: adjust vti mtu according to mtu of lower device
LTP/udp6_ipsec_vti tests fail when sending large UDP datagrams over ip6_vti that require fragmentation and the underlying device has an MTU smaller than 1500 plus some extra space for headers. This happens because ip6_vti, by default, 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(). In case the lower device has larger MTU size, e.g. 9000, ip6_vti works but not using the possible maximum size, output packets have 1500 limit. The above cases require manual MTU setup after ip6_vti creation. However ip_vti already updates MTU based on lower device with ip_tunnel_bind_dev(). Here is the example when the lower device MTU is set to 9000: # ip a sh ltp_ns_veth2 ltp_ns_veth2@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 ... inet 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 Reported-by: Petr Vorel <pvorel@suse.cz> Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/ip6_vti.c')
1 files changed, 20 insertions, 0 deletions
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index dbb74f3c57a7..18caa9539e6d 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 +639,25 @@ static void vti6_link_config(struct ip6_tnl *t)
dev->flags |= IFF_POINTOPOINT;
dev->flags &= ~IFF_POINTOPOINT;
+ if (p->flags & IP6_TNL_F_CAP_XMIT) {
+ int strict = (ipv6_addr_type(&p->raddr) &
+ 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,