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>
---
net/netfilter/nf_log_syslog.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c
index 77bcb10fc586..cb894f0d63e9 100644
--- a/net/netfilter/nf_log_syslog.c
+++ b/net/netfilter/nf_log_syslog.c
@@ -67,7 +67,7 @@ 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;
@@ -96,7 +96,7 @@ 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));
@@ -149,7 +149,7 @@ 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);
}
@@ -850,7 +850,7 @@ static void nf_log_ip_packet(struct net *net, u_int8_t pf,
if (in)
dump_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);
}
--
2.30.2
