Re: [PATCH v4 net-next 02/13] netfilter: bridge: Add conntrack double vlan and pppoe
From: Nikolay Aleksandrov <razor@blackwall.org>
Date: 2025-01-07 09:33:33
Also in:
bridge, linux-arm-kernel, linux-mediatek, lkml, netfilter-devel
On 1/7/25 11:05, Eric Woudstra wrote:
quoted hunk ↗ jump to hunk
This adds the capability to conntrack 802.1ad, QinQ, PPPoE and PPPoE-in-Q packets that are passing a bridge. Signed-off-by: Eric Woudstra <redacted> --- net/bridge/netfilter/nf_conntrack_bridge.c | 88 ++++++++++++++++++---- 1 file changed, 75 insertions(+), 13 deletions(-)diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c index 816bb0fde718..31e2bcd71735 100644 --- a/net/bridge/netfilter/nf_conntrack_bridge.c +++ b/net/bridge/netfilter/nf_conntrack_bridge.c@@ -241,56 +241,118 @@ static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { struct nf_hook_state bridge_state = *state; + __be16 outer_proto, inner_proto; enum ip_conntrack_info ctinfo; + int ret, offset = 0; struct nf_conn *ct; - u32 len; - int ret; + u32 len, data_len; ct = nf_ct_get(skb, &ctinfo); if ((ct && !nf_ct_is_template(ct)) || ctinfo == IP_CT_UNTRACKED) return NF_ACCEPT;
In all cases below I think you should make sure the headers are present in the linear part of the skb, either do pskb_may_pull() or use skb_header_pointer(). This is executed in the PRE bridge hook, so nothing has been pulled yet by it.
+ switch (skb->protocol) {
+ case htons(ETH_P_PPP_SES): {
+ struct ppp_hdr {
+ struct pppoe_hdr hdr;
+ __be16 proto;
+ } *ph = (struct ppp_hdr *)(skb->data);
+
+ data_len = ntohs(ph->hdr.length) - 2;
+ offset = PPPOE_SES_HLEN;
+ outer_proto = skb->protocol;
+ switch (ph->proto) {
+ case htons(PPP_IP):
+ inner_proto = htons(ETH_P_IP);
+ break;
+ case htons(PPP_IPV6):
+ inner_proto = htons(ETH_P_IPV6);
+ break;
+ default:
+ return NF_ACCEPT;
+ }
+ break;
+ }
+ case htons(ETH_P_8021Q): {
+ struct vlan_hdr *vhdr = (struct vlan_hdr *)(skb->data);
+
+ data_len = 0xffffffff;
+ offset = VLAN_HLEN;
+ outer_proto = skb->protocol;
+ inner_proto = vhdr->h_vlan_encapsulated_proto;
+ break;
+ }
+ default:
+ data_len = 0xffffffff;
+ break;
+ }
+
+ if (offset) {
+ switch (inner_proto) {
+ case htons(ETH_P_IP):
+ case htons(ETH_P_IPV6):
+ if (!pskb_may_pull(skb, offset))
+ return NF_ACCEPT;
+ skb_pull_rcsum(skb, offset);> + skb_reset_network_header(skb);
+ skb->protocol = inner_proto;
+ break;
+ default:
+ return NF_ACCEPT;
+ }
+ }
+
+ ret = NF_ACCEPT;
switch (skb->protocol) {
case htons(ETH_P_IP):
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
- return NF_ACCEPT;
+ goto do_not_track;
len = skb_ip_totlen(skb);
+ if (data_len < len)
+ len = data_len;
if (pskb_trim_rcsum(skb, len))
- return NF_ACCEPT;
+ goto do_not_track;
if (nf_ct_br_ip_check(skb))
- return NF_ACCEPT;
+ goto do_not_track;
bridge_state.pf = NFPROTO_IPV4;
ret = nf_ct_br_defrag4(skb, &bridge_state);
break;
case htons(ETH_P_IPV6):
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
- return NF_ACCEPT;
+ goto do_not_track;
len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+ if (data_len < len)
+ len = data_len;
if (pskb_trim_rcsum(skb, len))
- return NF_ACCEPT;
+ goto do_not_track;
if (nf_ct_br_ipv6_check(skb))
- return NF_ACCEPT;
+ goto do_not_track;
bridge_state.pf = NFPROTO_IPV6;
ret = nf_ct_br_defrag6(skb, &bridge_state);
break;
default:
nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
- return NF_ACCEPT;
+ goto do_not_track;
}
- if (ret != NF_ACCEPT)
- return ret;
+ if (ret == NF_ACCEPT)
+ ret = nf_conntrack_in(skb, &bridge_state);
- return nf_conntrack_in(skb, &bridge_state);
+do_not_track:
+ if (offset) {
+ skb_push_rcsum(skb, offset);
+ skb_reset_network_header(skb);
+ skb->protocol = outer_proto;
+ }
+ return ret;
}
-
static unsigned int nf_ct_bridge_in(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state)
{