linux-kernel - [PATCH v1] audit: include source and destination ports to NETFILTER

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Message-ID: <20250922200942.1534414-1-rrobaina@redhat.com>
Date: Mon, 22 Sep 2025 17:09:42 -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,
	Ricardo Robaina <rrobaina@...hat.com>
Subject: [PATCH v1] 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, only to tcp/udp-related
NETFILTER_PKT records.

 # ./audit-testsuite/tests/netfilter_pkt/test &> /dev/null
 # ausearch -i -m netfilter_pkt |tail -n12
 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

Link: https://github.com/linux-audit/audit-kernel/issues/162
Signed-off-by: Ricardo Robaina <rrobaina@...hat.com>
---
 net/netfilter/xt_AUDIT.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/xt_AUDIT.c b/net/netfilter/xt_AUDIT.c
index b6a015aee0ce..96a18675d468 100644
--- a/net/netfilter/xt_AUDIT.c
+++ b/net/netfilter/xt_AUDIT.c
@@ -32,6 +32,7 @@ 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 +41,19 @@ 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:
+		sport = udp_hdr(skb)->source;
+		dport = udp_hdr(skb)->dest;
+	}
+
+	if (ih->protocol == IPPROTO_TCP || ih->protocol == IPPROTO_UDP)
+		audit_log_format(ab, " sport=%hu dport=%hu", ntohs(sport), ntohs(dport));
+
 	return true;
 }
 
@@ -48,7 +62,7 @@ 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 +74,19 @@ 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:
+		sport = udp_hdr(skb)->source;
+		dport = udp_hdr(skb)->dest;
+	}
+
+	if (ih->nexthdr == IPPROTO_TCP || ih->nexthdr == IPPROTO_UDP)
+		audit_log_format(ab, " sport=%hu dport=%hu", ntohs(sport), ntohs(dport));
+
 	return true;
 }
 
-- 
2.51.0