v4.19.13 snapshot.
diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
new file mode 100644
index 0000000..d97f4f2
--- /dev/null
+++ b/net/ipv4/ipcomp.c
@@ -0,0 +1,204 @@
+/*
+ * IP Payload Compression Protocol (IPComp) - RFC3173.
+ *
+ * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Todo:
+ * - Tunable compression parameters.
+ * - Compression stats.
+ * - Adaptive compression.
+ */
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/rtnetlink.h>
+#include <net/ip.h>
+#include <net/xfrm.h>
+#include <net/icmp.h>
+#include <net/ipcomp.h>
+#include <net/protocol.h>
+#include <net/sock.h>
+
+static int ipcomp4_err(struct sk_buff *skb, u32 info)
+{
+ struct net *net = dev_net(skb->dev);
+ __be32 spi;
+ const struct iphdr *iph = (const struct iphdr *)skb->data;
+ struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
+ struct xfrm_state *x;
+
+ switch (icmp_hdr(skb)->type) {
+ case ICMP_DEST_UNREACH:
+ if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
+ return 0;
+ case ICMP_REDIRECT:
+ break;
+ default:
+ return 0;
+ }
+
+ spi = htonl(ntohs(ipch->cpi));
+ x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
+ spi, IPPROTO_COMP, AF_INET);
+ if (!x)
+ return 0;
+
+ if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
+ ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_COMP, 0);
+ else
+ ipv4_redirect(skb, net, 0, 0, IPPROTO_COMP, 0);
+ xfrm_state_put(x);
+
+ return 0;
+}
+
+/* We always hold one tunnel user reference to indicate a tunnel */
+static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
+{
+ struct net *net = xs_net(x);
+ struct xfrm_state *t;
+
+ t = xfrm_state_alloc(net);
+ if (!t)
+ goto out;
+
+ t->id.proto = IPPROTO_IPIP;
+ t->id.spi = x->props.saddr.a4;
+ t->id.daddr.a4 = x->id.daddr.a4;
+ memcpy(&t->sel, &x->sel, sizeof(t->sel));
+ t->props.family = AF_INET;
+ t->props.mode = x->props.mode;
+ t->props.saddr.a4 = x->props.saddr.a4;
+ t->props.flags = x->props.flags;
+ t->props.extra_flags = x->props.extra_flags;
+ memcpy(&t->mark, &x->mark, sizeof(t->mark));
+
+ if (xfrm_init_state(t))
+ goto error;
+
+ atomic_set(&t->tunnel_users, 1);
+out:
+ return t;
+
+error:
+ t->km.state = XFRM_STATE_DEAD;
+ xfrm_state_put(t);
+ t = NULL;
+ goto out;
+}
+
+/*
+ * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
+ * always incremented on success.
+ */
+static int ipcomp_tunnel_attach(struct xfrm_state *x)
+{
+ struct net *net = xs_net(x);
+ int err = 0;
+ struct xfrm_state *t;
+ u32 mark = x->mark.v & x->mark.m;
+
+ t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4,
+ x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
+ if (!t) {
+ t = ipcomp_tunnel_create(x);
+ if (!t) {
+ err = -EINVAL;
+ goto out;
+ }
+ xfrm_state_insert(t);
+ xfrm_state_hold(t);
+ }
+ x->tunnel = t;
+ atomic_inc(&t->tunnel_users);
+out:
+ return err;
+}
+
+static int ipcomp4_init_state(struct xfrm_state *x)
+{
+ int err = -EINVAL;
+
+ x->props.header_len = 0;
+ switch (x->props.mode) {
+ case XFRM_MODE_TRANSPORT:
+ break;
+ case XFRM_MODE_TUNNEL:
+ x->props.header_len += sizeof(struct iphdr);
+ break;
+ default:
+ goto out;
+ }
+
+ err = ipcomp_init_state(x);
+ if (err)
+ goto out;
+
+ if (x->props.mode == XFRM_MODE_TUNNEL) {
+ err = ipcomp_tunnel_attach(x);
+ if (err)
+ goto out;
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static int ipcomp4_rcv_cb(struct sk_buff *skb, int err)
+{
+ return 0;
+}
+
+static const struct xfrm_type ipcomp_type = {
+ .description = "IPCOMP4",
+ .owner = THIS_MODULE,
+ .proto = IPPROTO_COMP,
+ .init_state = ipcomp4_init_state,
+ .destructor = ipcomp_destroy,
+ .input = ipcomp_input,
+ .output = ipcomp_output
+};
+
+static struct xfrm4_protocol ipcomp4_protocol = {
+ .handler = xfrm4_rcv,
+ .input_handler = xfrm_input,
+ .cb_handler = ipcomp4_rcv_cb,
+ .err_handler = ipcomp4_err,
+ .priority = 0,
+};
+
+static int __init ipcomp4_init(void)
+{
+ if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
+ pr_info("%s: can't add xfrm type\n", __func__);
+ return -EAGAIN;
+ }
+ if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
+ pr_info("%s: can't add protocol\n", __func__);
+ xfrm_unregister_type(&ipcomp_type, AF_INET);
+ return -EAGAIN;
+ }
+ return 0;
+}
+
+static void __exit ipcomp4_fini(void)
+{
+ if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0)
+ pr_info("%s: can't remove protocol\n", __func__);
+ if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
+ pr_info("%s: can't remove xfrm type\n", __func__);
+}
+
+module_init(ipcomp4_init);
+module_exit(ipcomp4_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
+MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
+
+MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);