[PATCH net-next v4 1/7] ipv6: Check of max HBH or DestOp sysctl is zero and drop if it is

[Tom Herbert <tom@herbertland.com>]

In IPv6 Destination options processing function check if
net->ipv6.sysctl.max_dst_opts_cnt is zero up front. If it is zero then
drop the packet since Destination Options processing is disabled.

Similarly, in IPv6 hop-by-hop options processing function check if
net->ipv6.sysctl.max_hbh_opts_cnt is zero up front. If it is zero then
drop the packet since Hop-by-Hop Options processing is disabled.

Signed-off-by: Tom Herbert <tom@herbertland.com>
---
 net/ipv6/exthdrs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 54088fa0c09d..45bbad76f5de 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -303,7 +303,8 @@ static int ipv6_destopt_rcv(struct sk_buff *skb)
 	struct net *net = dev_net(skb->dev);
 	int extlen;
 
-	if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
+	if (!net->ipv6.sysctl.max_dst_opts_cnt ||
+	    !pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
 	    !pskb_may_pull(skb, (skb_transport_offset(skb) +
 				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
 		__IP6_INC_STATS(dev_net(dst_dev(dst)), idev,
@@ -1041,7 +1042,8 @@ int ipv6_parse_hopopts(struct sk_buff *skb)
 	 * sizeof(struct ipv6hdr) by definition of
 	 * hop-by-hop options.
 	 */
-	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
+	if (!net->ipv6.sysctl.max_hbh_opts_cnt ||
+	    !pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
 	    !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
 				 ((skb_transport_header(skb)[1] + 1) << 3)))) {
 fail_and_free:
-- 
2.43.0