1 files changed, 39 insertions, 0 deletions

diff --git a/net/ipv6/netfilter/ip6t_NPT.c b/net/ipv6/netfilter/ip6t_NPT.c
index 9ee077bf4f49..787c74aa85e3 100644
--- a/net/ipv6/netfilter/ip6t_NPT.c
+++ b/net/ipv6/netfilter/ip6t_NPT.c
@@ -77,16 +77,43 @@ static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
 	return true;
 }
 
+static struct ipv6hdr *icmpv6_bounced_ipv6hdr(struct sk_buff *skb,
+					      struct ipv6hdr *_bounced_hdr)
+{
+	if (ipv6_hdr(skb)->nexthdr != IPPROTO_ICMPV6)
+		return NULL;
+
+	if (!icmpv6_is_err(icmp6_hdr(skb)->icmp6_type))
+		return NULL;
+
+	return skb_header_pointer(skb,
+				  skb_transport_offset(skb) + sizeof(struct icmp6hdr),
+				  sizeof(struct ipv6hdr),
+				  _bounced_hdr);
+}
+
 static unsigned int
 ip6t_snpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	const struct ip6t_npt_tginfo *npt = par->targinfo;
+	struct ipv6hdr _bounced_hdr;
+	struct ipv6hdr *bounced_hdr;
+	struct in6_addr bounced_pfx;
 
 	if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->saddr)) {
 		icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
 			    offsetof(struct ipv6hdr, saddr));
 		return NF_DROP;
 	}
+
+	/* rewrite dst addr of bounced packet which was sent to dst range */
+	bounced_hdr = icmpv6_bounced_ipv6hdr(skb, &_bounced_hdr);
+	if (bounced_hdr) {
+		ipv6_addr_prefix(&bounced_pfx, &bounced_hdr->daddr, npt->src_pfx_len);
+		if (ipv6_addr_cmp(&bounced_pfx, &npt->src_pfx.in6) == 0)
+			ip6t_npt_map_pfx(npt, &bounced_hdr->daddr);
+	}
+
 	return XT_CONTINUE;
 }
 
@@ -94,12 +121,24 @@ static unsigned int
 ip6t_dnpt_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	const struct ip6t_npt_tginfo *npt = par->targinfo;
+	struct ipv6hdr _bounced_hdr;
+	struct ipv6hdr *bounced_hdr;
+	struct in6_addr bounced_pfx;
 
 	if (!ip6t_npt_map_pfx(npt, &ipv6_hdr(skb)->daddr)) {
 		icmpv6_send(skb, ICMPV6_PARAMPROB, ICMPV6_HDR_FIELD,
 			    offsetof(struct ipv6hdr, daddr));
 		return NF_DROP;
 	}
+
+	/* rewrite src addr of bounced packet which was sent from dst range */
+	bounced_hdr = icmpv6_bounced_ipv6hdr(skb, &_bounced_hdr);
+	if (bounced_hdr) {
+		ipv6_addr_prefix(&bounced_pfx, &bounced_hdr->saddr, npt->src_pfx_len);
+		if (ipv6_addr_cmp(&bounced_pfx, &npt->src_pfx.in6) == 0)
+			ip6t_npt_map_pfx(npt, &bounced_hdr->saddr);
+	}
+
 	return XT_CONTINUE;
 }