v4.19.13 snapshot.
diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
new file mode 100644
index 0000000..856d2df
--- /dev/null
+++ b/net/ipv4/xfrm4_mode_beet.c
@@ -0,0 +1,155 @@
+/*
+ * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4.
+ *
+ * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
+ * Miika Komu <miika@iki.fi>
+ * Herbert Xu <herbert@gondor.apana.org.au>
+ * Abhinav Pathak <abhinav.pathak@hiit.fi>
+ * Jeff Ahrenholz <ahrenholz@gmail.com>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/stringify.h>
+#include <net/dst.h>
+#include <net/ip.h>
+#include <net/xfrm.h>
+
+static void xfrm4_beet_make_header(struct sk_buff *skb)
+{
+ struct iphdr *iph = ip_hdr(skb);
+
+ iph->ihl = 5;
+ iph->version = 4;
+
+ iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
+ iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
+
+ iph->id = XFRM_MODE_SKB_CB(skb)->id;
+ iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off;
+ iph->ttl = XFRM_MODE_SKB_CB(skb)->ttl;
+}
+
+/* Add encapsulation header.
+ *
+ * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
+ */
+static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+ struct ip_beet_phdr *ph;
+ struct iphdr *top_iph;
+ int hdrlen, optlen;
+
+ hdrlen = 0;
+ optlen = XFRM_MODE_SKB_CB(skb)->optlen;
+ if (unlikely(optlen))
+ hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
+
+ skb_set_network_header(skb, -x->props.header_len -
+ hdrlen + (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
+ if (x->sel.family != AF_INET6)
+ skb->network_header += IPV4_BEET_PHMAXLEN;
+ skb->mac_header = skb->network_header +
+ offsetof(struct iphdr, protocol);
+ skb->transport_header = skb->network_header + sizeof(*top_iph);
+
+ xfrm4_beet_make_header(skb);
+
+ ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
+
+ top_iph = ip_hdr(skb);
+
+ if (unlikely(optlen)) {
+ BUG_ON(optlen < 0);
+
+ ph->padlen = 4 - (optlen & 4);
+ ph->hdrlen = optlen / 8;
+ ph->nexthdr = top_iph->protocol;
+ if (ph->padlen)
+ memset(ph + 1, IPOPT_NOP, ph->padlen);
+
+ top_iph->protocol = IPPROTO_BEETPH;
+ top_iph->ihl = sizeof(struct iphdr) / 4;
+ }
+
+ top_iph->saddr = x->props.saddr.a4;
+ top_iph->daddr = x->id.daddr.a4;
+
+ return 0;
+}
+
+static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+ struct iphdr *iph;
+ int optlen = 0;
+ int err = -EINVAL;
+
+ if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
+ struct ip_beet_phdr *ph;
+ int phlen;
+
+ if (!pskb_may_pull(skb, sizeof(*ph)))
+ goto out;
+
+ ph = (struct ip_beet_phdr *)skb->data;
+
+ phlen = sizeof(*ph) + ph->padlen;
+ optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
+ if (optlen < 0 || optlen & 3 || optlen > 250)
+ goto out;
+
+ XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;
+
+ if (!pskb_may_pull(skb, phlen))
+ goto out;
+ __skb_pull(skb, phlen);
+ }
+
+ skb_push(skb, sizeof(*iph));
+ skb_reset_network_header(skb);
+ skb_mac_header_rebuild(skb);
+
+ xfrm4_beet_make_header(skb);
+
+ iph = ip_hdr(skb);
+
+ iph->ihl += optlen / 4;
+ iph->tot_len = htons(skb->len);
+ iph->daddr = x->sel.daddr.a4;
+ iph->saddr = x->sel.saddr.a4;
+ iph->check = 0;
+ iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
+ err = 0;
+out:
+ return err;
+}
+
+static struct xfrm_mode xfrm4_beet_mode = {
+ .input2 = xfrm4_beet_input,
+ .input = xfrm_prepare_input,
+ .output2 = xfrm4_beet_output,
+ .output = xfrm4_prepare_output,
+ .owner = THIS_MODULE,
+ .encap = XFRM_MODE_BEET,
+ .flags = XFRM_MODE_FLAG_TUNNEL,
+};
+
+static int __init xfrm4_beet_init(void)
+{
+ return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
+}
+
+static void __exit xfrm4_beet_exit(void)
+{
+ int err;
+
+ err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
+ BUG_ON(err);
+}
+
+module_init(xfrm4_beet_init);
+module_exit(xfrm4_beet_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);