Patch "netfilter: nf_log: incorrect offset to network header" has been added to the 5.18-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    netfilter: nf_log: incorrect offset to network header

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-nf_log-incorrect-offset-to-network-header.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit b4d91e5fad9754320a7b012b5b30b94c85cb6f38
Author: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Date:   Tue Jul 5 10:26:15 2022 +0200

    netfilter: nf_log: incorrect offset to network header
    
    [ Upstream commit 7a847c00eeba9744353ecdfad253143b9115678a ]
    
    NFPROTO_ARP is expecting to find the ARP header at the network offset.
    
    In the particular case of ARP, HTYPE= field shows the initial bytes of
    the ethernet header destination MAC address.
    
     netdev out: IN= OUT=bridge0 MACSRC=c2:76:e5:71:e1:de MACDST=36:b0:4a:e2:72:ea MACPROTO=0806 ARP HTYPE=14000 PTYPE=0x4ae2 OPCODE=49782
    
    NFPROTO_NETDEV egress hook is also expecting to find the IP headers at
    the network offset.
    
    Fixes: 35b9395104d5 ("netfilter: add generic ARP packet logger")
    Reported-by: Tom Yan <tom.ty89@xxxxxxxxx>
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c
index 13234641cdb3..7000e069bc07 100644
--- a/net/netfilter/nf_log_syslog.c
+++ b/net/netfilter/nf_log_syslog.c
@@ -61,7 +61,7 @@ dump_arp_packet(struct nf_log_buf *m,
 	unsigned int logflags;
 	struct arphdr _arph;
 
-	ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
+	ah = skb_header_pointer(skb, nhoff, sizeof(_arph), &_arph);
 	if (!ah) {
 		nf_log_buf_add(m, "TRUNCATED");
 		return;
@@ -90,7 +90,7 @@ dump_arp_packet(struct nf_log_buf *m,
 	    ah->ar_pln != sizeof(__be32))
 		return;
 
-	ap = skb_header_pointer(skb, sizeof(_arph), sizeof(_arpp), &_arpp);
+	ap = skb_header_pointer(skb, nhoff + sizeof(_arph), sizeof(_arpp), &_arpp);
 	if (!ap) {
 		nf_log_buf_add(m, " INCOMPLETE [%zu bytes]",
 			       skb->len - sizeof(_arph));
@@ -144,7 +144,7 @@ static void nf_log_arp_packet(struct net *net, u_int8_t pf,
 
 	nf_log_dump_packet_common(m, pf, hooknum, skb, in, out, loginfo,
 				  prefix);
-	dump_arp_packet(m, loginfo, skb, 0);
+	dump_arp_packet(m, loginfo, skb, skb_network_offset(skb));
 
 	nf_log_buf_close(m);
 }
@@ -829,7 +829,7 @@ static void nf_log_ip_packet(struct net *net, u_int8_t pf,
 	if (in)
 		dump_ipv4_mac_header(m, loginfo, skb);
 
-	dump_ipv4_packet(net, m, loginfo, skb, 0);
+	dump_ipv4_packet(net, m, loginfo, skb, skb_network_offset(skb));
 
 	nf_log_buf_close(m);
 }