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authorAlexey Kodanev <alexey.kodanev@oracle.com>2017-12-19 16:59:21 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-03-24 10:58:48 +0100
commit2fe832c678189d6b19b5ff282e7e70df79c1406b (patch)
treec05ec75433fedb1d4bb9743fb07949e4ff0f402f
parentfb4ff6c7329fb7a64ae5a6410e6611161a2c751e (diff)
ip6_vti: adjust vti mtu according to mtu of lower device
[ Upstream commit 53c81e95df1793933f87748d36070a721f6cb287 ] 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 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 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> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv6/ip6_vti.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index d7105422bc63..e4b0fb2f06a3 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -614,6 +614,7 @@ 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));
@@ -626,6 +627,25 @@ 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);
}
/**