[PATCH 4.17 34/66] net/ipv6: Fix linklocal to global address with VRF

From: Greg Kroah-Hartman
Date: Fri Jul 27 2018 - 05:49:22 EST


4.17-stable review patch. If anyone has any objections, please let me know.

------------------

From: David Ahern <dsahern@xxxxxxxxx>

[ Upstream commit 24b711edfc34bc45777a3f068812b7d1ed004a5d ]

Example setup:
host: ip -6 addr add dev eth1 2001:db8:104::4
where eth1 is enslaved to a VRF

switch: ip -6 ro add 2001:db8:104::4/128 dev br1
where br1 only has an LLA

ping6 2001:db8:104::4
ssh 2001:db8:104::4

(NOTE: UDP works fine if the PKTINFO has the address set to the global
address and ifindex is set to the index of eth1 with a destination an
LLA).

For ICMP, icmp6_iif needs to be updated to check if skb->dev is an
L3 master. If it is then return the ifindex from rt6i_idev similar
to what is done for loopback.

For TCP, restore the original tcp_v6_iif definition which is needed in
most places and add a new tcp_v6_iif_l3_slave that considers the
l3_slave variability. This latter check is only needed for socket
lookups.

Fixes: 9ff74384600a ("net: vrf: Handle ipv6 multicast and link-local addresses")
Signed-off-by: David Ahern <dsahern@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/tcp.h | 5 +++++
net/ipv6/icmp.c | 5 +++--
net/ipv6/tcp_ipv6.c | 6 ++++--
3 files changed, 12 insertions(+), 4 deletions(-)

--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -829,6 +829,11 @@ struct tcp_skb_cb {
*/
static inline int tcp_v6_iif(const struct sk_buff *skb)
{
+ return TCP_SKB_CB(skb)->header.h6.iif;
+}
+
+static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
+{
bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);

return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -402,9 +402,10 @@ static int icmp6_iif(const struct sk_buf

/* for local traffic to local address, skb dev is the loopback
* device. Check if there is a dst attached to the skb and if so
- * get the real device index.
+ * get the real device index. Same is needed for replies to a link
+ * local address on a device enslaved to an L3 master device
*/
- if (unlikely(iif == LOOPBACK_IFINDEX)) {
+ if (unlikely(iif == LOOPBACK_IFINDEX || netif_is_l3_master(skb->dev))) {
const struct rt6_info *rt6 = skb_rt6_info(skb);

if (rt6)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -934,7 +934,8 @@ static void tcp_v6_send_reset(const stru
&tcp_hashinfo, NULL, 0,
&ipv6h->saddr,
th->source, &ipv6h->daddr,
- ntohs(th->source), tcp_v6_iif(skb),
+ ntohs(th->source),
+ tcp_v6_iif_l3_slave(skb),
tcp_v6_sdif(skb));
if (!sk1)
goto out;
@@ -1605,7 +1606,8 @@ do_time_wait:
skb, __tcp_hdrlen(th),
&ipv6_hdr(skb)->saddr, th->source,
&ipv6_hdr(skb)->daddr,
- ntohs(th->dest), tcp_v6_iif(skb),
+ ntohs(th->dest),
+ tcp_v6_iif_l3_slave(skb),
sdif);
if (sk2) {
struct inet_timewait_sock *tw = inet_twsk(sk);