From f7789419137b18e3847d0cc41afd788c3c00663d Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Tue, 30 Apr 2024 18:50:13 +0200 Subject: vxlan: Pull inner IP header in vxlan_rcv(). Ensure the inner IP header is part of skb's linear data before reading its ECN bits. Otherwise we might read garbage. One symptom is the system erroneously logging errors like "vxlan: non-ECT from xxx.xxx.xxx.xxx with TOS=xxxx". Similar bugs have been fixed in geneve, ip_tunnel and ip6_tunnel (see commit 1ca1ba465e55 ("geneve: make sure to pull inner header in geneve_rx()") for example). So let's reuse the same code structure for consistency. Maybe we'll can add a common helper in the future. Fixes: d342894c5d2f ("vxlan: virtual extensible lan") Signed-off-by: Guillaume Nault Reviewed-by: Ido Schimmel Reviewed-by: Eric Dumazet Reviewed-by: Nikolay Aleksandrov Reviewed-by: Sabrina Dubroca Link: https://lore.kernel.org/r/1239c8db54efec341dd6455c77e0380f58923a3c.1714495737.git.gnault@redhat.com Signed-off-by: Jakub Kicinski --- drivers/net/vxlan/vxlan_core.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index c9e4e03ad214..3a9148fb1422 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -1674,6 +1674,7 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb) bool raw_proto = false; void *oiph; __be32 vni = 0; + int nh; /* Need UDP and VXLAN header to be present */ if (!pskb_may_pull(skb, VXLAN_HLEN)) @@ -1762,9 +1763,25 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb) skb->pkt_type = PACKET_HOST; } - oiph = skb_network_header(skb); + /* Save offset of outer header relative to skb->head, + * because we are going to reset the network header to the inner header + * and might change skb->head. + */ + nh = skb_network_header(skb) - skb->head; + skb_reset_network_header(skb); + if (!pskb_inet_may_pull(skb)) { + DEV_STATS_INC(vxlan->dev, rx_length_errors); + DEV_STATS_INC(vxlan->dev, rx_errors); + vxlan_vnifilter_count(vxlan, vni, vninode, + VXLAN_VNI_STATS_RX_ERRORS, 0); + goto drop; + } + + /* Get the outer header. */ + oiph = skb->head + nh; + if (!vxlan_ecn_decapsulate(vs, oiph, skb)) { DEV_STATS_INC(vxlan->dev, rx_frame_errors); DEV_STATS_INC(vxlan->dev, rx_errors); -- cgit v1.2.3