[PATCH 5.4 220/348] vrf: do not push non-ND strict packets with a source LLA through packet taps again

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 02:28:51 EST

From: Antoine Tenart <atenart@xxxxxxxxxx>

[ Upstream commit 603113c514e95c3350598bc3cccbd03af7ea4ab2 ]

Non-ND strict packets with a source LLA go through the packet taps
again, while non-ND strict packets with other source addresses do not,
and we can see a clone of those packets on the vrf interface (we should
not). This is due to a series of changes:

Commit 6f12fa775530[1] made non-ND strict packets not being pushed again
in the packet taps. This changed with commit 205704c618af[2] for those
packets having a source LLA, as they need a lookup with the orig_iif.

The issue now is those packets do not skip the 'vrf_ip6_rcv' function to
the end (as the ones without a source LLA) and go through the check to
call packet taps again. This check was changed by commit 6f12fa775530[1]
and do not exclude non-strict packets anymore. Packets matching
'need_strict && !is_ndisc && is_ll_src' are now being sent through the
packet taps again. This can be seen by dumping packets on the vrf

Fix this by having the same code path for all non-ND strict packets and
selectively lookup with the orig_iif for those with a source LLA. This
has the effect to revert to the pre-205704c618af[2] condition, which
should also be easier to maintain.

[1] 6f12fa775530 ("vrf: mark skb for multicast or link-local as enslaved to VRF")
[2] 205704c618af ("vrf: packets with lladdr src needs dst at input with orig_iif when needs strict")

Fixes: 205704c618af ("vrf: packets with lladdr src needs dst at input with orig_iif when needs strict")
Cc: Stephen Suryaputra <ssuryaextr@xxxxxxxxx>
Reported-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Antoine Tenart <atenart@xxxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/net/vrf.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 1267786d2931..f08ed52d51f3 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -1035,22 +1035,22 @@ static struct sk_buff *vrf_ip6_rcv(struct net_device *vrf_dev,
int orig_iif = skb->skb_iif;
bool need_strict = rt6_need_strict(&ipv6_hdr(skb)->daddr);
bool is_ndisc = ipv6_ndisc_frame(skb);
- bool is_ll_src;

/* loopback, multicast & non-ND link-local traffic; do not push through
* packet taps again. Reset pkt_type for upper layers to process skb.
- * for packets with lladdr src, however, skip so that the dst can be
- * determine at input using original ifindex in the case that daddr
- * needs strict
+ * For strict packets with a source LLA, determine the dst using the
+ * original ifindex.
- is_ll_src = ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL;
- if (skb->pkt_type == PACKET_LOOPBACK ||
- (need_strict && !is_ndisc && !is_ll_src)) {
+ if (skb->pkt_type == PACKET_LOOPBACK || (need_strict && !is_ndisc)) {
skb->dev = vrf_dev;
skb->skb_iif = vrf_dev->ifindex;
IP6CB(skb)->flags |= IP6SKB_L3SLAVE;
if (skb->pkt_type == PACKET_LOOPBACK)
skb->pkt_type = PACKET_HOST;
+ else if (ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)
+ vrf_ip6_input_dst(skb, vrf_dev, orig_iif);
goto out;