[PATCH net-next v4 02/10] ip6_tunnel: add drop reasons to the generic RX path
From: Anton Danilov <hidden>
Date: 2026-09-22 22:15:22
Also in:
lkml
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
__ip6_tnl_rcv() mirrors its IPv4 counterpart: all of its failures share a single plain kfree_skb(). Reuse the drop reasons that ip_tunnel_rcv() now reports and the ones the length helpers already return. Note that skb_vlan_inet_prepare() returns an enum skb_drop_reason that has so far been discarded, and that the ETH_HLEN check gets one by calling pskb_may_pull_reason() instead of pskb_may_pull(). __ip6_tnl_rcv() is reached two ways: ip6_gre (ip6gre, ip6gretap, ip6erspan) goes through the exported ip6_tnl_rcv(), while the ip6_tunnel encapsulations (ip4ip6, ip6ip6, mplsip6) reach it from ipxip6_rcv(). Only ip6_gre sets the checksum and sequence number bits: tpi_v4, tpi_v6 and tpi_mpls carry nothing but .proto, and unlike ipip and sit, ip6_tunnel stores IFLA_IPTUN_FLAGS in parms.flags, not in parms.i_flags. So the option mismatch and the old sequence reasons are reachable through ip6_gre alone. Assisted-by: Claude-Code:claude-opus-5 Signed-off-by: Anton Danilov <redacted> --- net/ipv6/ip6_tunnel.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index d5ff50a2ac01..458ce328311b 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c@@ -813,6 +813,7 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, struct sk_buff *skb), bool log_ecn_err) { + enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; const struct ipv6hdr *ipv6h; int nh, err;
@@ -820,15 +821,22 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, test_bit(IP_TUNNEL_CSUM_BIT, tpi->flags)) { DEV_STATS_INC(tunnel->dev, rx_crc_errors); DEV_STATS_INC(tunnel->dev, rx_errors); + reason = SKB_DROP_REASON_TNL_OPT_MISMATCH; goto drop; } if (test_bit(IP_TUNNEL_SEQ_BIT, tunnel->parms.i_flags)) { - if (!test_bit(IP_TUNNEL_SEQ_BIT, tpi->flags) || - (tunnel->i_seqno && - (s32)(ntohl(tpi->seq) - tunnel->i_seqno) < 0)) { + if (!test_bit(IP_TUNNEL_SEQ_BIT, tpi->flags)) { DEV_STATS_INC(tunnel->dev, rx_fifo_errors); DEV_STATS_INC(tunnel->dev, rx_errors); + reason = SKB_DROP_REASON_TNL_OPT_MISMATCH; + goto drop; + } + if (tunnel->i_seqno && + (s32)(ntohl(tpi->seq) - tunnel->i_seqno) < 0) { + DEV_STATS_INC(tunnel->dev, rx_fifo_errors); + DEV_STATS_INC(tunnel->dev, rx_errors); + reason = SKB_DROP_REASON_TNL_OLD_SEQ; goto drop; } tunnel->i_seqno = ntohl(tpi->seq) + 1;
@@ -838,7 +846,8 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, /* Warning: All skb pointers will be invalidated! */ if (tunnel->dev->type == ARPHRD_ETHER) { - if (!pskb_may_pull(skb, ETH_HLEN)) { + reason = pskb_may_pull_reason(skb, ETH_HLEN); + if (reason) { DEV_STATS_INC(tunnel->dev, rx_length_errors); DEV_STATS_INC(tunnel->dev, rx_errors); goto drop;
@@ -859,7 +868,8 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, skb_reset_network_header(skb); - if (skb_vlan_inet_prepare(skb, true)) { + reason = skb_vlan_inet_prepare(skb, true); + if (reason) { DEV_STATS_INC(tunnel->dev, rx_length_errors); DEV_STATS_INC(tunnel->dev, rx_errors); goto drop;
@@ -881,6 +891,7 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, if (err > 1) { DEV_STATS_INC(tunnel->dev, rx_frame_errors); DEV_STATS_INC(tunnel->dev, rx_errors); + reason = SKB_DROP_REASON_IP_TUNNEL_ECN; goto drop; } }
@@ -898,7 +909,7 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb, drop: if (tun_dst) dst_release((struct dst_entry *)tun_dst); - kfree_skb(skb); + kfree_skb_reason(skb, reason); return 0; }
--
2.47.3