From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: fw@strlen.de, ericwouds@gmail.com
Subject: [PATCH nf-next,v2] netfilter: nft_meta: add double-tagged vlan and pppoe support
Date: Mon, 16 Mar 2026 12:51:31 +0100 [thread overview]
Message-ID: <20260316115131.3834908-1-pablo@netfilter.org> (raw)
Currently:
add rule netdev x y ip saddr 1.1.1.1
does not work with neither double-tagged vlan nor pppoe packets. This is
because the network and transport header offset are not pointing to the
IP and transport protocol headers in the stack.
This patch expands NFT_META_PROTOCOL and NFT_META_L4PROTO to parse
double-tagged vlan and pppoe packets so matching network and transport
header fields becomes possible with the existing userspace generated
bytecode.
NFT_META_PROTOCOL is used by bridge and netdev family as an implicit
dependency in the bytecode to match on network header fields.
Similarly, there is also NFT_META_L4PROTO, which is also used as an
implicit dependency when matching on the transport protocol header
fields.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v2: fixes incorrect offsets (now nftables/tests/shell passes).
Tested via scapy with PPP packet:
from scapy.all import *
# Craft PPPoE session packet with IP payload
pkt = Ether()/PPPoE(sessionid=0x0100)/PPP(proto=0x0021)/IP(src="2.2.2.2", dst="1.1.1.1")/ICMP()
# Send on br0 interface
sendp(pkt, iface="br0", verbose=0)
print("PPPoE packet injected on br0")
And this simple ruleset:
table netdev x {
chain y {
type filter hook ingress device eth0 priority 0;
ip daddr 1.1.1.1 counter
}
}
include/net/netfilter/nf_tables.h | 4 ++
include/net/netfilter/nf_tables_ipv4.h | 17 +++++---
include/net/netfilter/nf_tables_ipv6.h | 16 ++++---
net/netfilter/nf_tables_core.c | 2 +-
net/netfilter/nft_meta.c | 60 +++++++++++++++++++++++++-
net/netfilter/nft_payload.c | 2 +-
6 files changed, 88 insertions(+), 13 deletions(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index ea6f29ad7888..566df9e7dcb7 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -31,7 +31,9 @@ struct nft_pktinfo {
const struct nf_hook_state *state;
u8 flags;
u8 tprot;
+ __be16 ethertype;
u16 fragoff;
+ u16 nhoff;
u16 thoff;
u16 inneroff;
};
@@ -83,6 +85,8 @@ static inline void nft_set_pktinfo_unspec(struct nft_pktinfo *pkt)
{
pkt->flags = 0;
pkt->tprot = 0;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = 0;
pkt->thoff = 0;
pkt->fragoff = 0;
}
diff --git a/include/net/netfilter/nf_tables_ipv4.h b/include/net/netfilter/nf_tables_ipv4.h
index fcf967286e37..e715405a73cb 100644
--- a/include/net/netfilter/nf_tables_ipv4.h
+++ b/include/net/netfilter/nf_tables_ipv4.h
@@ -12,16 +12,19 @@ static inline void nft_set_pktinfo_ipv4(struct nft_pktinfo *pkt)
ip = ip_hdr(pkt->skb);
pkt->flags = NFT_PKTINFO_L4PROTO;
pkt->tprot = ip->protocol;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = 0;
pkt->thoff = ip_hdrlen(pkt->skb);
pkt->fragoff = ntohs(ip->frag_off) & IP_OFFSET;
}
-static inline int __nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt)
+static inline int __nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt,
+ int nhoff)
{
struct iphdr *iph, _iph;
u32 len, thoff, skb_len;
- iph = skb_header_pointer(pkt->skb, skb_network_offset(pkt->skb),
+ iph = skb_header_pointer(pkt->skb, skb_network_offset(pkt->skb) + nhoff,
sizeof(*iph), &_iph);
if (!iph)
return -1;
@@ -31,7 +34,7 @@ static inline int __nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt)
len = iph_totlen(pkt->skb, iph);
thoff = iph->ihl * 4;
- skb_len = pkt->skb->len - skb_network_offset(pkt->skb);
+ skb_len = pkt->skb->len - skb_network_offset(pkt->skb) - nhoff;
if (skb_len < len)
return -1;
@@ -42,7 +45,9 @@ static inline int __nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt)
pkt->flags = NFT_PKTINFO_L4PROTO;
pkt->tprot = iph->protocol;
- pkt->thoff = skb_network_offset(pkt->skb) + thoff;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = nhoff;
+ pkt->thoff = skb_network_offset(pkt->skb) + nhoff + thoff;
pkt->fragoff = ntohs(iph->frag_off) & IP_OFFSET;
return 0;
@@ -50,7 +55,7 @@ static inline int __nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt)
static inline void nft_set_pktinfo_ipv4_validate(struct nft_pktinfo *pkt)
{
- if (__nft_set_pktinfo_ipv4_validate(pkt) < 0)
+ if (__nft_set_pktinfo_ipv4_validate(pkt, 0) < 0)
nft_set_pktinfo_unspec(pkt);
}
@@ -78,6 +83,8 @@ static inline int nft_set_pktinfo_ipv4_ingress(struct nft_pktinfo *pkt)
}
pkt->flags = NFT_PKTINFO_L4PROTO;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = 0;
pkt->tprot = iph->protocol;
pkt->thoff = thoff;
pkt->fragoff = ntohs(iph->frag_off) & IP_OFFSET;
diff --git a/include/net/netfilter/nf_tables_ipv6.h b/include/net/netfilter/nf_tables_ipv6.h
index c53ac00bb974..d7b8c559b795 100644
--- a/include/net/netfilter/nf_tables_ipv6.h
+++ b/include/net/netfilter/nf_tables_ipv6.h
@@ -20,21 +20,23 @@ static inline void nft_set_pktinfo_ipv6(struct nft_pktinfo *pkt)
pkt->flags = NFT_PKTINFO_L4PROTO;
pkt->tprot = protohdr;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = 0;
pkt->thoff = thoff;
pkt->fragoff = frag_off;
}
-static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
+static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt, int nhoff)
{
#if IS_ENABLED(CONFIG_IPV6)
unsigned int flags = IP6_FH_F_AUTH;
struct ipv6hdr *ip6h, _ip6h;
- unsigned int thoff = 0;
+ unsigned int thoff = nhoff;
unsigned short frag_off;
u32 pkt_len, skb_len;
int protohdr;
- ip6h = skb_header_pointer(pkt->skb, skb_network_offset(pkt->skb),
+ ip6h = skb_header_pointer(pkt->skb, skb_network_offset(pkt->skb) + nhoff,
sizeof(*ip6h), &_ip6h);
if (!ip6h)
return -1;
@@ -43,7 +45,7 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
return -1;
pkt_len = ipv6_payload_len(pkt->skb, ip6h);
- skb_len = pkt->skb->len - skb_network_offset(pkt->skb);
+ skb_len = pkt->skb->len - skb_network_offset(pkt->skb) - nhoff;
if (pkt_len + sizeof(*ip6h) > skb_len)
return -1;
@@ -53,6 +55,8 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
pkt->flags = NFT_PKTINFO_L4PROTO;
pkt->tprot = protohdr;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = nhoff;
pkt->thoff = thoff;
pkt->fragoff = frag_off;
@@ -64,7 +68,7 @@ static inline int __nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
static inline void nft_set_pktinfo_ipv6_validate(struct nft_pktinfo *pkt)
{
- if (__nft_set_pktinfo_ipv6_validate(pkt) < 0)
+ if (__nft_set_pktinfo_ipv6_validate(pkt, 0) < 0)
nft_set_pktinfo_unspec(pkt);
}
@@ -99,6 +103,8 @@ static inline int nft_set_pktinfo_ipv6_ingress(struct nft_pktinfo *pkt)
pkt->flags = NFT_PKTINFO_L4PROTO;
pkt->tprot = protohdr;
+ pkt->ethertype = pkt->skb->protocol;
+ pkt->nhoff = 0;
pkt->thoff = thoff;
pkt->fragoff = frag_off;
diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 6557a4018c09..5ddd5b6e135f 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -151,7 +151,7 @@ static bool nft_payload_fast_eval(const struct nft_expr *expr,
unsigned char *ptr;
if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
- ptr = skb_network_header(skb);
+ ptr = skb_network_header(skb) + pkt->nhoff;
else {
if (!(pkt->flags & NFT_PKTINFO_L4PROTO))
return false;
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index 05cd1e6e6a2f..60b84e21d225 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -23,6 +23,8 @@
#include <net/tcp_states.h> /* for TCP_TIME_WAIT */
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
+#include <net/netfilter/nf_tables_ipv4.h>
+#include <net/netfilter/nf_tables_ipv6.h>
#include <net/netfilter/nft_meta.h>
#include <net/netfilter/nf_tables_offload.h>
@@ -306,6 +308,61 @@ nft_meta_get_eval_sdifname(u32 *dest, const struct nft_pktinfo *pkt)
nft_meta_store_ifname(dest, dev);
}
+static void nft_meta_pktinfo_may_update(struct nft_pktinfo *pkt)
+{
+ struct sk_buff *skb = pkt->skb;
+ struct vlan_ethhdr *veth;
+ __be16 ethertype;
+ int nhoff;
+
+ /* Is this an IP packet? Then, skip. */
+ if (pkt->flags)
+ return;
+
+ /* ... else maybe an IP packer over PPPoE or Q-in-Q? */
+ switch (skb->protocol) {
+ case htons(ETH_P_8021Q):
+ if (!pskb_may_pull(skb, skb_mac_offset(skb) + sizeof(*veth)))
+ return;
+
+ veth = (struct vlan_ethhdr *)skb_mac_header(skb);
+ nhoff = VLAN_HLEN;
+ ethertype = veth->h_vlan_encapsulated_proto;
+ break;
+ case htons(ETH_P_PPP_SES):
+ if (!nf_flow_pppoe_proto(skb, ðertype))
+ return;
+
+ nhoff = PPPOE_SES_HLEN;
+ break;
+ default:
+ return;
+ }
+
+ nhoff += skb_network_offset(skb);
+ switch (ethertype) {
+ case htons(ETH_P_IP):
+ if (__nft_set_pktinfo_ipv4_validate(pkt, nhoff))
+ nft_set_pktinfo_unspec(pkt);
+ break;
+ case htons(ETH_P_IPV6):
+ if (__nft_set_pktinfo_ipv6_validate(pkt, nhoff))
+ nft_set_pktinfo_unspec(pkt);
+ break;
+ default:
+ break;
+ }
+
+ pkt->ethertype = ethertype;
+}
+
+static void nft_meta_protocol_store(u32 *dest, struct nft_pktinfo *pkt)
+{
+ nft_meta_pktinfo_may_update(pkt);
+
+ nft_reg_store16(dest, (__force u16)pkt->ethertype);
+}
+
void nft_meta_get_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@@ -319,12 +376,13 @@ void nft_meta_get_eval(const struct nft_expr *expr,
*dest = skb->len;
break;
case NFT_META_PROTOCOL:
- nft_reg_store16(dest, (__force u16)skb->protocol);
+ nft_meta_protocol_store(dest, (struct nft_pktinfo *)pkt);
break;
case NFT_META_NFPROTO:
nft_reg_store8(dest, nft_pf(pkt));
break;
case NFT_META_L4PROTO:
+ nft_meta_pktinfo_may_update((struct nft_pktinfo *)pkt);
if (!(pkt->flags & NFT_PKTINFO_L4PROTO))
goto err;
nft_reg_store8(dest, pkt->tprot);
diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
index b0214418f75a..c334dd0ff86c 100644
--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -183,7 +183,7 @@ void nft_payload_eval(const struct nft_expr *expr,
offset = skb_mac_header(skb) - skb->data;
break;
case NFT_PAYLOAD_NETWORK_HEADER:
- offset = skb_network_offset(skb);
+ offset = skb_network_offset(skb) + pkt->nhoff;
break;
case NFT_PAYLOAD_TRANSPORT_HEADER:
if (!(pkt->flags & NFT_PKTINFO_L4PROTO) || pkt->fragoff)
--
2.47.3
next reply other threads:[~2026-03-16 11:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 11:51 Pablo Neira Ayuso [this message]
-- strict thread matches above, loose matches on Subject: below --
2026-03-22 22:51 [PATCH nf-next,v2] netfilter: nft_meta: add double-tagged vlan and pppoe support Pablo Neira Ayuso
2026-03-23 17:55 ` Pablo Neira Ayuso
2026-03-23 20:44 ` Pablo Neira Ayuso
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