[PATCH net-next v4 04/10] ip_tunnel: add __iptunnel_pull_header_reason()
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COOLING13d
From: Anton Danilov <hidden>
Date: 2026-09-22 22:15:28
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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
Revision v4 of 5 in this series.
Revisions (5)
__iptunnel_pull_header() returns -ENOMEM whenever it fails. It can fail in two pskb_may_pull() calls, one for the tunnel header and one for the inner Ethernet header of ETH_P_TEB, and in the skb_unclone() done for GSO packets. pskb_may_pull() fails when the packet is shorter than the requested length as well as when pulling from the frags cannot allocate, so a truncated packet and an allocation failure look the same to the callers. The ones that report a drop reason can only pick SKB_DROP_REASON_NOMEM, as vxlan_rcv() does, and so would the GRE receive paths converted by the following patches. In ip6_gre, gre_rcv() calls the helper before the tunnel lookup, so a packet from any sender whose ETH_P_TEB inner Ethernet header or WCCPv2 extra word is cut short would be reported as an out of memory condition. Add __iptunnel_pull_header_reason(), which returns the reason pskb_may_pull_reason() already computes, SKB_DROP_REASON_NOMEM when skb_unclone() fails, and SKB_NOT_DROPPED_YET on success. Turn __iptunnel_pull_header() into a static inline wrapper that keeps returning -ENOMEM on any failure, so its existing callers are left unchanged; the export moves to the new function. Assisted-by: Claude-Code:claude-opus-5 Signed-off-by: Anton Danilov <redacted> --- include/net/ip_tunnels.h | 13 +++++++++++-- net/ipv4/ip_tunnel_core.c | 24 ++++++++++++++++-------- 2 files changed, 27 insertions(+), 10 deletions(-)
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 7102aa11fae2..c68031d01c39 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h@@ -614,8 +614,17 @@ static inline u8 ip_tunnel_ecn_encap(u8 tos, const struct iphdr *iph, return INET_ECN_encapsulate(tos, inner); } -int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len, - __be16 inner_proto, bool raw_proto, bool xnet); +enum skb_drop_reason +__iptunnel_pull_header_reason(struct sk_buff *skb, int hdr_len, + __be16 inner_proto, bool raw_proto, bool xnet); + +static inline int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len, + __be16 inner_proto, bool raw_proto, + bool xnet) +{ + return __iptunnel_pull_header_reason(skb, hdr_len, inner_proto, + raw_proto, xnet) ? -ENOMEM : 0; +} static inline int iptunnel_pull_header(struct sk_buff *skb, int hdr_len, __be16 inner_proto, bool xnet)
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index bab42b9e277f..51f1537ce6c1 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c@@ -106,19 +106,24 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb, } EXPORT_SYMBOL_GPL(iptunnel_xmit); -int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len, - __be16 inner_proto, bool raw_proto, bool xnet) +enum skb_drop_reason +__iptunnel_pull_header_reason(struct sk_buff *skb, int hdr_len, + __be16 inner_proto, bool raw_proto, bool xnet) { - if (unlikely(!pskb_may_pull(skb, hdr_len))) - return -ENOMEM; + enum skb_drop_reason reason; + + reason = pskb_may_pull_reason(skb, hdr_len); + if (unlikely(reason)) + return reason; skb_pull_rcsum(skb, hdr_len); if (!raw_proto && inner_proto == htons(ETH_P_TEB)) { struct ethhdr *eh; - if (unlikely(!pskb_may_pull(skb, ETH_HLEN))) - return -ENOMEM; + reason = pskb_may_pull_reason(skb, ETH_HLEN); + if (unlikely(reason)) + return reason; eh = (struct ethhdr *)skb->data; if (likely(eth_proto_is_802_3(eh->h_proto)))
@@ -135,9 +140,12 @@ int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len, skb_set_queue_mapping(skb, 0); skb_scrub_packet(skb, xnet); - return iptunnel_pull_offloads(skb); + if (unlikely(iptunnel_pull_offloads(skb))) + return SKB_DROP_REASON_NOMEM; + + return SKB_NOT_DROPPED_YET; } -EXPORT_SYMBOL_GPL(__iptunnel_pull_header); +EXPORT_SYMBOL_GPL(__iptunnel_pull_header_reason); struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md, gfp_t flags)
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2.47.3