[PATCH nf-next v5 5/6] af_packet: Introduce egress hook
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2021-09-28 09:55:55
Also in:
netfilter-devel
Subsystem:
networking [general], packet sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Willem de Bruijn, Linus Torvalds
Add egress hook for AF_PACKET sockets that have the PACKET_QDISC_BYPASS socket option set to on, which allows packets to escape without being filtered in the egress path. This patch only updates the AF_PACKET path, it does not update dev_direct_xmit() so the XDP infrastructure has a chance to bypass Netfilter. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> [lukas: acquire rcu_read_lock, fix typos, rebase] Signed-off-by: Lukas Wunner <lukas@wunner.de> --- net/packet/af_packet.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2a2bc64f75cf..46943a18a10d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c@@ -91,6 +91,7 @@ #endif #include <linux/bpf.h> #include <net/compat.h> +#include <linux/netfilter_netdev.h> #include "internal.h"
@@ -241,8 +242,42 @@ struct packet_skb_cb { static void __fanout_unlink(struct sock *sk, struct packet_sock *po); static void __fanout_link(struct sock *sk, struct packet_sock *po); +#ifdef CONFIG_NETFILTER_EGRESS +static noinline struct sk_buff *nf_hook_direct_egress(struct sk_buff *skb) +{ + struct sk_buff *next, *head = NULL, *tail; + int rc; + + rcu_read_lock(); + for (; skb != NULL; skb = next) { + next = skb->next; + skb_mark_not_on_list(skb); + + if (!nf_hook_egress(skb, &rc, skb->dev)) + continue; + + if (!head) + head = skb; + else + tail->next = skb; + + tail = skb; + } + rcu_read_unlock(); + + return head; +} +#endif + static int packet_direct_xmit(struct sk_buff *skb) { +#ifdef CONFIG_NETFILTER_EGRESS + if (nf_hook_egress_active()) { + skb = nf_hook_direct_egress(skb); + if (!skb) + return NET_XMIT_DROP; + } +#endif return dev_direct_xmit(skb, packet_pick_tx_queue(skb)); }
--
2.30.2