{"id":2231324,"url":"http://patchwork.ozlabs.org/api/patches/2231324/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260430154217.260522-2-pablo@netfilter.org/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260430154217.260522-2-pablo@netfilter.org>","list_archive_url":null,"date":"2026-04-30T15:42:16","name":"[nf,v6,2/3] netfilter: flowtable: fix inline vlan encapsulation in xmit path","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"7337221df1853a7e8a6e8660884750cbc1df0dbf","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260430154217.260522-2-pablo@netfilter.org/mbox/","series":[{"id":502332,"url":"http://patchwork.ozlabs.org/api/series/502332/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=502332","date":"2026-04-30T15:42:16","name":"[nf,v6,1/3] netfilter: flowtable: ensure sufficient headroom in xmit path","version":6,"mbox":"http://patchwork.ozlabs.org/series/502332/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2231324/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2231324/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n <netfilter-devel+bounces-12340-incoming=patchwork.ozlabs.org@vger.kernel.org>","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=netfilter.org header.i=@netfilter.org\n header.a=rsa-sha256 header.s=2025 header.b=PVtESuCb;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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Reverse the encap loop to push first the inner then the outer vlan\n  header.\n\n- Postpone pushing the layer 2 header once destination device is known.\n  This allows to calculate the needed hearoom via LL_RESERVED_SPACE to\n  accommodate the layer 2 headers.\n\n- Add and use nf_flow_vlan_push() as suggested by Eric Woudstra, this\n  is a simplified version of skb_vlan_push() for egress path only.\n\nFixes: c653d5a78f34 (\"netfilter: flowtable: inline vlan encapsulation in xmit path\")\nSigned-off-by: Pablo Neira Ayuso <pablo@netfilter.org>\n---\nv6: no changes.\n\n net/netfilter/nf_flow_table_ip.c | 109 ++++++++++++++++++++-----------\n 1 file changed, 72 insertions(+), 37 deletions(-)","diff":"diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c\nindex 8d5fb7e940a1..54263878451b 100644\n--- a/net/netfilter/nf_flow_table_ip.c\n+++ b/net/netfilter/nf_flow_table_ip.c\n@@ -462,32 +462,6 @@ static void nf_flow_encap_pop(struct nf_flowtable_ctx *ctx,\n \t\tnf_flow_ip_tunnel_pop(ctx, skb);\n }\n \n-struct nf_flow_xmit {\n-\tconst void\t\t*dest;\n-\tconst void\t\t*source;\n-\tstruct net_device\t*outdev;\n-};\n-\n-static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,\n-\t\t\t\t       struct nf_flow_xmit *xmit)\n-{\n-\tstruct net_device *dev = xmit->outdev;\n-\tunsigned int hh_len = LL_RESERVED_SPACE(dev);\n-\n-\tif (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {\n-\t\tskb = skb_expand_head(skb, hh_len);\n-\t\tif (!skb)\n-\t\t\treturn NF_STOLEN;\n-\t}\n-\n-\tskb->dev = dev;\n-\tdev_hard_header(skb, dev, ntohs(skb->protocol),\n-\t\t\txmit->dest, xmit->source, skb->len);\n-\tdev_queue_xmit(skb);\n-\n-\treturn NF_STOLEN;\n-}\n-\n static struct flow_offload_tuple_rhash *\n nf_flow_offload_lookup(struct nf_flowtable_ctx *ctx,\n \t\t       struct nf_flowtable *flow_table, struct sk_buff *skb)\n@@ -553,6 +527,31 @@ static int nf_flow_offload_forward(struct nf_flowtable_ctx *ctx,\n \treturn 1;\n }\n \n+/* Similar to skb_vlan_push. */\n+static int nf_flow_vlan_push(struct sk_buff *skb, __be16 proto, u16 id,\n+\t\t\t     u32 needed_headroom)\n+{\n+\tif (skb_vlan_tag_present(skb)) {\n+\t\tstruct vlan_hdr *vhdr;\n+\n+\t\tif (skb_cow_head(skb, needed_headroom + VLAN_HLEN))\n+\t\t\treturn -1;\n+\n+\t\t__skb_push(skb, VLAN_HLEN);\n+\t\tif (skb_mac_header_was_set(skb))\n+\t\t\tskb->mac_header -= VLAN_HLEN;\n+\n+\t\tvhdr = (struct vlan_hdr *)skb->data;\n+\t\tskb->network_header -= VLAN_HLEN;\n+\t\tvhdr->h_vlan_TCI = htons(skb_vlan_tag_get(skb));\n+\t\tvhdr->h_vlan_encapsulated_proto = skb->protocol;\n+\t\tskb->protocol = skb->vlan_proto;\n+\t}\n+\t__vlan_hwaccel_put_tag(skb, proto, id);\n+\n+\treturn 0;\n+}\n+\n static int nf_flow_pppoe_push(struct sk_buff *skb, u16 id)\n {\n \tint data_len = skb->len + sizeof(__be16);\n@@ -739,17 +738,19 @@ static int nf_flow_tunnel_v6_push(struct net *net, struct sk_buff *skb,\n }\n \n static int nf_flow_encap_push(struct sk_buff *skb,\n-\t\t\t      struct flow_offload_tuple *tuple)\n+\t\t\t      struct flow_offload_tuple *tuple,\n+\t\t\t      struct net_device *outdev)\n {\n+\tu32 needed_headroom = LL_RESERVED_SPACE(outdev);\n \tint i;\n \n-\tfor (i = 0; i < tuple->encap_num; i++) {\n+\tfor (i = tuple->encap_num - 1; i >= 0; i--) {\n \t\tswitch (tuple->encap[i].proto) {\n \t\tcase htons(ETH_P_8021Q):\n \t\tcase htons(ETH_P_8021AD):\n-\t\t\tskb_reset_mac_header(skb);\n-\t\t\tif (skb_vlan_push(skb, tuple->encap[i].proto,\n-\t\t\t\t\t  tuple->encap[i].id) < 0)\n+\t\t\tif (nf_flow_vlan_push(skb, tuple->encap[i].proto,\n+\t\t\t\t\t      tuple->encap[i].id,\n+\t\t\t\t\t      needed_headroom) < 0)\n \t\t\t\treturn -1;\n \t\t\tbreak;\n \t\tcase htons(ETH_P_PPP_SES):\n@@ -762,6 +763,44 @@ static int nf_flow_encap_push(struct sk_buff *skb,\n \treturn 0;\n }\n \n+struct nf_flow_xmit {\n+\tconst void\t\t*dest;\n+\tconst void\t\t*source;\n+\tstruct net_device\t*outdev;\n+\tstruct flow_offload_tuple *tuple;\n+};\n+\n+static void __nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,\n+\t\t\t\t struct nf_flow_xmit *xmit)\n+{\n+\tstruct net_device *dev = xmit->outdev;\n+\tunsigned int hh_len = LL_RESERVED_SPACE(dev);\n+\n+\tif (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {\n+\t\tskb = skb_expand_head(skb, hh_len);\n+\t\tif (!skb)\n+\t\t\treturn;\n+\t}\n+\n+\tskb->dev = dev;\n+\tdev_hard_header(skb, dev, ntohs(skb->protocol),\n+\t\t\txmit->dest, xmit->source, skb->len);\n+\tdev_queue_xmit(skb);\n+}\n+\n+static unsigned int nf_flow_queue_xmit(struct net *net, struct sk_buff *skb,\n+\t\t\t\t       struct nf_flow_xmit *xmit)\n+{\n+\tif (xmit->tuple->encap_num) {\n+\t\tif (nf_flow_encap_push(skb, xmit->tuple, xmit->outdev) < 0)\n+\t\t\treturn NF_DROP;\n+\t}\n+\n+\t__nf_flow_queue_xmit(net, skb, xmit);\n+\n+\treturn NF_STOLEN;\n+}\n+\n unsigned int\n nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,\n \t\t\tconst struct nf_hook_state *state)\n@@ -806,9 +845,6 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,\n \tif (nf_flow_tunnel_v4_push(state->net, skb, other_tuple, &ip_daddr) < 0)\n \t\treturn NF_DROP;\n \n-\tif (nf_flow_encap_push(skb, other_tuple) < 0)\n-\t\treturn NF_DROP;\n-\n \tswitch (tuplehash->tuple.xmit_type) {\n \tcase FLOW_OFFLOAD_XMIT_NEIGH:\n \t\trt = dst_rtable(tuplehash->tuple.dst_cache);\n@@ -838,6 +874,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,\n \t\tWARN_ON_ONCE(1);\n \t\treturn NF_DROP;\n \t}\n+\txmit.tuple = other_tuple;\n \n \treturn nf_flow_queue_xmit(state->net, skb, &xmit);\n }\n@@ -1128,9 +1165,6 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,\n \t\t\t\t   &ip6_daddr, encap_limit) < 0)\n \t\treturn NF_DROP;\n \n-\tif (nf_flow_encap_push(skb, other_tuple) < 0)\n-\t\treturn NF_DROP;\n-\n \tswitch (tuplehash->tuple.xmit_type) {\n \tcase FLOW_OFFLOAD_XMIT_NEIGH:\n \t\trt = dst_rt6_info(tuplehash->tuple.dst_cache);\n@@ -1160,6 +1194,7 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,\n \t\tWARN_ON_ONCE(1);\n \t\treturn NF_DROP;\n \t}\n+\txmit.tuple = other_tuple;\n \n \treturn nf_flow_queue_xmit(state->net, skb, &xmit);\n }\n","prefixes":["nf","v6","2/3"]}