1 files changed, 112 insertions, 0 deletions
diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c
new file mode 100644
index 000000000..ad0790464
--- /dev/null
+++ b/net/ipv6/xfrm6_output.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
+ * Copyright (C) 2002 USAGI/WIDE Project
+ * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <linux/if_ether.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/icmpv6.h>
+#include <linux/netfilter_ipv6.h>
+#include <net/dst.h>
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/xfrm.h>
+
+void xfrm6_local_rxpmtu(struct sk_buff *skb, u32 mtu)
+{
+	struct flowi6 fl6;
+	struct sock *sk = skb->sk;
+
+	fl6.flowi6_oif = sk->sk_bound_dev_if;
+	fl6.daddr = ipv6_hdr(skb)->daddr;
+
+	ipv6_local_rxpmtu(sk, &fl6, mtu);
+}
+
+void xfrm6_local_error(struct sk_buff *skb, u32 mtu)
+{
+	struct flowi6 fl6;
+	const struct ipv6hdr *hdr;
+	struct sock *sk = skb->sk;
+
+	hdr = skb->encapsulation ? inner_ipv6_hdr(skb) : ipv6_hdr(skb);
+	fl6.fl6_dport = inet_sk(sk)->inet_dport;
+	fl6.daddr = hdr->daddr;
+
+	ipv6_local_error(sk, EMSGSIZE, &fl6, mtu);
+}
+
+static int __xfrm6_output_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	return xfrm_output(sk, skb);
+}
+
+static int xfrm6_noneed_fragment(struct sk_buff *skb)
+{
+	struct frag_hdr *fh;
+	u8 prevhdr = ipv6_hdr(skb)->nexthdr;
+
+	if (prevhdr != NEXTHDR_FRAGMENT)
+		return 0;
+	fh = (struct frag_hdr *)(skb->data + sizeof(struct ipv6hdr));
+	if (fh->nexthdr == NEXTHDR_ESP || fh->nexthdr == NEXTHDR_AUTH)
+		return 1;
+	return 0;
+}
+
+static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	struct xfrm_state *x = dst->xfrm;
+	unsigned int mtu;
+	bool toobig;
+
+#ifdef CONFIG_NETFILTER
+	if (!x) {
+		IP6CB(skb)->flags |= IP6SKB_REROUTED;
+		return dst_output(net, sk, skb);
+	}
+#endif
+
+	if (x->props.mode != XFRM_MODE_TUNNEL)
+		goto skip_frag;
+
+	if (skb->protocol == htons(ETH_P_IPV6))
+		mtu = ip6_skb_dst_mtu(skb);
+	else
+		mtu = dst_mtu(skb_dst(skb));
+
+	toobig = skb->len > mtu && !skb_is_gso(skb);
+
+	if (toobig && xfrm6_local_dontfrag(skb->sk)) {
+		xfrm6_local_rxpmtu(skb, mtu);
+		kfree_skb(skb);
+		return -EMSGSIZE;
+	} else if (toobig && xfrm6_noneed_fragment(skb)) {
+		skb->ignore_df = 1;
+		goto skip_frag;
+	} else if (!skb->ignore_df && toobig && skb->sk) {
+		xfrm_local_error(skb, mtu);
+		kfree_skb(skb);
+		return -EMSGSIZE;
+	}
+
+	if (toobig || dst_allfrag(skb_dst(skb)))
+		return ip6_fragment(net, sk, skb,
+				    __xfrm6_output_finish);
+
+skip_frag:
+	return xfrm_output(sk, skb);
+}
+
+int xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
+			    net, sk, skb,  skb->dev, skb_dst(skb)->dev,
+			    __xfrm6_output,
+			    !(IP6CB(skb)->flags & IP6SKB_REROUTED));
+}