From: Nicolas Dichtel nicolas.dichtel@6wind.com
[ Upstream commit 95224166a9032ff5d08fca633d37113078ce7d01 ]
With an ebpf program that redirects packets through a vti[6] interface, the packets are dropped because no dst is attached.
This could also be reproduced with an AF_PACKET socket, with the following python script (vti1 is an ip_vti interface):
import socket send_s = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, 0) # scapy # p = IP(src='10.100.0.2', dst='10.200.0.1')/ICMP(type='echo-request') # raw(p) req = b'E\x00\x00\x1c\x00\x01\x00\x00@\x01e\xb2\nd\x00\x02\n\xc8\x00\x01\x08\x00\xf7\xff\x00\x00\x00\x00' send_s.sendto(req, ('vti1', 0x800, 0, 0))
Signed-off-by: Nicolas Dichtel nicolas.dichtel@6wind.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/ip_vti.c | 13 +++++++++++-- net/ipv6/ip6_vti.c | 13 +++++++++++-- 2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c index fb9f6d60c27cd..79eef5db336a4 100644 --- a/net/ipv4/ip_vti.c +++ b/net/ipv4/ip_vti.c @@ -187,8 +187,17 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev, int mtu;
if (!dst) { - dev->stats.tx_carrier_errors++; - goto tx_error_icmp; + struct rtable *rt; + + fl->u.ip4.flowi4_oif = dev->ifindex; + fl->u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC; + rt = __ip_route_output_key(dev_net(dev), &fl->u.ip4); + if (IS_ERR(rt)) { + dev->stats.tx_carrier_errors++; + goto tx_error_icmp; + } + dst = &rt->dst; + skb_dst_set(skb, dst); }
dst_hold(dst); diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index 6f08b760c2a7c..524006aa0d78a 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -449,8 +449,17 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl) int err = -1; int mtu;
- if (!dst) - goto tx_err_link_failure; + if (!dst) { + fl->u.ip6.flowi6_oif = dev->ifindex; + fl->u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC; + dst = ip6_route_output(dev_net(dev), NULL, &fl->u.ip6); + if (dst->error) { + dst_release(dst); + dst = NULL; + goto tx_err_link_failure; + } + skb_dst_set(skb, dst); + }
dst_hold(dst); dst = xfrm_lookup(t->net, dst, fl, NULL, 0);