linux-kernel - [PATCH v2] audit: include source and destination ports to NETFILTER

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Message-ID: <20250925134156.1948142-1-rrobaina@redhat.com>
Date: Thu, 25 Sep 2025 10:41:56 -0300
From: Ricardo Robaina <rrobaina@...hat.com>
To: audit@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	netfilter-devel@...r.kernel.org,
	coreteam@...filter.org
Cc: paul@...l-moore.com,
	eparis@...hat.com,
	pablo@...filter.org,
	kadlec@...filter.org,
	fw@...len.de,
	ej@...i.de,
	Ricardo Robaina <rrobaina@...hat.com>
Subject: [PATCH v2] audit: include source and destination ports to NETFILTER_PKT

NETFILTER_PKT records show both source and destination
addresses, in addition to the associated networking protocol.
However, it lacks the ports information, which is often
valuable for troubleshooting.

This patch adds both source and destination port numbers,
'sport' and 'dport' respectively, to TCP, UDP, UDP-Lite and
SCTP-related NETFILTER_PKT records.

 type=NETFILTER_PKT ... saddr=127.0.0.1 daddr=127.0.0.1 proto=icmp
 type=NETFILTER_PKT ... saddr=::1 daddr=::1 proto=ipv6-icmp
 type=NETFILTER_PKT ... daddr=127.0.0.1 proto=udp sport=38173 dport=42424
 type=NETFILTER_PKT ... daddr=::1 proto=udp sport=56852 dport=42424
 type=NETFILTER_PKT ... daddr=127.0.0.1 proto=tcp sport=57022 dport=42424
 type=NETFILTER_PKT ... daddr=::1 proto=tcp sport=50810 dport=42424
 type=NETFILTER_PKT ... daddr=127.0.0.1 proto=sctp sport=54944 dport=42424
 type=NETFILTER_PKT ... daddr=::1 proto=sctp sport=57963 dport=42424

Link: https://github.com/linux-audit/audit-kernel/issues/162
Signed-off-by: Ricardo Robaina <rrobaina@...hat.com>
---
 net/netfilter/xt_AUDIT.c | 42 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/xt_AUDIT.c b/net/netfilter/xt_AUDIT.c
index b6a015aee0ce..9fc8a5429fa9 100644
--- a/net/netfilter/xt_AUDIT.c
+++ b/net/netfilter/xt_AUDIT.c
@@ -19,6 +19,7 @@
 #include <linux/netfilter_bridge/ebtables.h>
 #include <net/ipv6.h>
 #include <net/ip.h>
+#include <linux/sctp.h>
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Thomas Graf <tgraf@...hat.com>");
@@ -32,6 +33,7 @@ static bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
 {
 	struct iphdr _iph;
 	const struct iphdr *ih;
+	__be16 dport, sport;
 
 	ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_iph), &_iph);
 	if (!ih)
@@ -40,6 +42,25 @@ static bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
 	audit_log_format(ab, " saddr=%pI4 daddr=%pI4 proto=%hhu",
 			 &ih->saddr, &ih->daddr, ih->protocol);
 
+	switch (ih->protocol) {
+	case IPPROTO_TCP:
+		sport = tcp_hdr(skb)->source;
+		dport = tcp_hdr(skb)->dest;
+		break;
+	case IPPROTO_UDP:
+	case IPPROTO_UDPLITE:
+		sport = udp_hdr(skb)->source;
+		dport = udp_hdr(skb)->dest;
+		break;
+	case IPPROTO_SCTP:
+		sport = sctp_hdr(skb)->source;
+		dport = sctp_hdr(skb)->dest;
+	}
+
+	if (ih->protocol == IPPROTO_TCP || ih->protocol == IPPROTO_UDP ||
+	    ih->protocol == IPPROTO_UDPLITE || ih->protocol == IPPROTO_SCTP)
+		audit_log_format(ab, " sport=%hu dport=%hu", ntohs(sport), ntohs(dport));
+
 	return true;
 }
 
@@ -48,7 +69,7 @@ static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
 	struct ipv6hdr _ip6h;
 	const struct ipv6hdr *ih;
 	u8 nexthdr;
-	__be16 frag_off;
+	__be16 frag_off, dport, sport;
 
 	ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
 	if (!ih)
@@ -60,6 +81,25 @@ static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
 	audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
 			 &ih->saddr, &ih->daddr, nexthdr);
 
+	switch (ih->nexthdr) {
+	case IPPROTO_TCP:
+		sport = tcp_hdr(skb)->source;
+		dport = tcp_hdr(skb)->dest;
+		break;
+	case IPPROTO_UDP:
+	case IPPROTO_UDPLITE:
+		sport = udp_hdr(skb)->source;
+		dport = udp_hdr(skb)->dest;
+		break;
+	case IPPROTO_SCTP:
+		sport = sctp_hdr(skb)->source;
+		dport = sctp_hdr(skb)->dest;
+	}
+
+	if (ih->nexthdr == IPPROTO_TCP || ih->nexthdr == IPPROTO_UDP ||
+	    ih->nexthdr == IPPROTO_UDPLITE || ih->nexthdr == IPPROTO_SCTP)
+		audit_log_format(ab, " sport=%hu dport=%hu", ntohs(sport), ntohs(dport));
+
 	return true;
 }
 
-- 
2.51.0