netfilter: fix regression in looped (broad|multi)cast's MAC handling

In commit a668aefe02c3 ("netfilter: nfnetlink_queue: fix OOB when mac
header was cleared"), the test for non-empty MAC header introduced in
commit 5616022f9da369 ("netfilter: fix looped (broad|multi)cast's MAC
handling") has been replaced with a test for a set MAC header.

This breaks the case when the MAC header has been reset (using
skb_reset_mac_header), as is the case with looped-back multicast
packets.  As a result, the packets ending up in NFQUEUE get a bogus
hwaddr interpreted from the first bytes of the IP header.

This patch adds a test for a non-empty MAC header in addition to the
test for a set MAC header.  The same two tests are also implemented in
nfnetlink_log.c, where the initial code of commit 5616022f9da369
("netfilter: fix looped (broad|multi)cast's MAC handling") has not been
touched, but where supposedly the same situation may happen.

Fixes: a668aefe02c3 ("netfilter: nfnetlink_queue: fix OOB when mac header was cleared")
Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index 691ef4cffdd907cf09d3a7e680ebe83ea5562ee0..7f83f9697fc14d4b661ef9d837ad9cf77b34d13b 100644 (file)
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -556,7 +556,8 @@ __build_packet_message(struct nfnl_log_net *log,
                goto nla_put_failure;
 
        if (indev && skb->dev &&
-           skb->mac_header != skb->network_header) {
+           skb_mac_header_was_set(skb) &&
+           skb_mac_header_len(skb) != 0) {
                struct nfulnl_msg_packet_hw phw;
                int len;
 

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 5837e8efc9c201ca64c0aa03e60d82c4858f1559..f0b9e21a24524beccdd7797f680dbd339f95758a 100644 (file)
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -560,7 +560,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
                goto nla_put_failure;
 
        if (indev && entskb->dev &&
-           skb_mac_header_was_set(entskb)) {
+           skb_mac_header_was_set(entskb) &&
+           skb_mac_header_len(entskb) != 0) {
                struct nfqnl_msg_packet_hw phw;
                int len;