1 files changed, 427 insertions, 0 deletions
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
new file mode 100644
index 000000000..711cd3b43
--- /dev/null
+++ b/net/core/lwtunnel.c
@@ -0,0 +1,427 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * lwtunnel	Infrastructure for light weight tunnels like mpls
+ *
+ * Authors:	Roopa Prabhu, <roopa@cumulusnetworks.com>
+ */
+
+#include <linux/capability.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/lwtunnel.h>
+#include <linux/in.h>
+#include <linux/init.h>
+#include <linux/err.h>
+
+#include <net/lwtunnel.h>
+#include <net/rtnetlink.h>
+#include <net/ip6_fib.h>
+#include <net/rtnh.h>
+
+DEFINE_STATIC_KEY_FALSE(nf_hooks_lwtunnel_enabled);
+EXPORT_SYMBOL_GPL(nf_hooks_lwtunnel_enabled);
+
+#ifdef CONFIG_MODULES
+
+static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
+{
+	/* Only lwt encaps implemented without using an interface for
+	 * the encap need to return a string here.
+	 */
+	switch (encap_type) {
+	case LWTUNNEL_ENCAP_MPLS:
+		return "MPLS";
+	case LWTUNNEL_ENCAP_ILA:
+		return "ILA";
+	case LWTUNNEL_ENCAP_SEG6:
+		return "SEG6";
+	case LWTUNNEL_ENCAP_BPF:
+		return "BPF";
+	case LWTUNNEL_ENCAP_SEG6_LOCAL:
+		return "SEG6LOCAL";
+	case LWTUNNEL_ENCAP_RPL:
+		return "RPL";
+	case LWTUNNEL_ENCAP_IOAM6:
+		return "IOAM6";
+	case LWTUNNEL_ENCAP_XFRM:
+		/* module autoload not supported for encap type */
+		return NULL;
+	case LWTUNNEL_ENCAP_IP6:
+	case LWTUNNEL_ENCAP_IP:
+	case LWTUNNEL_ENCAP_NONE:
+	case __LWTUNNEL_ENCAP_MAX:
+		/* should not have got here */
+		WARN_ON(1);
+		break;
+	}
+	return NULL;
+}
+
+#endif /* CONFIG_MODULES */
+
+struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
+{
+	struct lwtunnel_state *lws;
+
+	lws = kzalloc(sizeof(*lws) + encap_len, GFP_ATOMIC);
+
+	return lws;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_state_alloc);
+
+static const struct lwtunnel_encap_ops __rcu *
+		lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
+
+int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *ops,
+			   unsigned int num)
+{
+	if (num > LWTUNNEL_ENCAP_MAX)
+		return -ERANGE;
+
+	return !cmpxchg((const struct lwtunnel_encap_ops **)
+			&lwtun_encaps[num],
+			NULL, ops) ? 0 : -1;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_encap_add_ops);
+
+int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
+			   unsigned int encap_type)
+{
+	int ret;
+
+	if (encap_type == LWTUNNEL_ENCAP_NONE ||
+	    encap_type > LWTUNNEL_ENCAP_MAX)
+		return -ERANGE;
+
+	ret = (cmpxchg((const struct lwtunnel_encap_ops **)
+		       &lwtun_encaps[encap_type],
+		       ops, NULL) == ops) ? 0 : -1;
+
+	synchronize_net();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_encap_del_ops);
+
+int lwtunnel_build_state(struct net *net, u16 encap_type,
+			 struct nlattr *encap, unsigned int family,
+			 const void *cfg, struct lwtunnel_state **lws,
+			 struct netlink_ext_ack *extack)
+{
+	const struct lwtunnel_encap_ops *ops;
+	bool found = false;
+	int ret = -EINVAL;
+
+	if (encap_type == LWTUNNEL_ENCAP_NONE ||
+	    encap_type > LWTUNNEL_ENCAP_MAX) {
+		NL_SET_ERR_MSG_ATTR(extack, encap,
+				    "Unknown LWT encapsulation type");
+		return ret;
+	}
+
+	ret = -EOPNOTSUPP;
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[encap_type]);
+	if (likely(ops && ops->build_state && try_module_get(ops->owner)))
+		found = true;
+	rcu_read_unlock();
+
+	if (found) {
+		ret = ops->build_state(net, encap, family, cfg, lws, extack);
+		if (ret)
+			module_put(ops->owner);
+	} else {
+		/* don't rely on -EOPNOTSUPP to detect match as build_state
+		 * handlers could return it
+		 */
+		NL_SET_ERR_MSG_ATTR(extack, encap,
+				    "LWT encapsulation type not supported");
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_build_state);
+
+int lwtunnel_valid_encap_type(u16 encap_type, struct netlink_ext_ack *extack)
+{
+	const struct lwtunnel_encap_ops *ops;
+	int ret = -EINVAL;
+
+	if (encap_type == LWTUNNEL_ENCAP_NONE ||
+	    encap_type > LWTUNNEL_ENCAP_MAX) {
+		NL_SET_ERR_MSG(extack, "Unknown lwt encapsulation type");
+		return ret;
+	}
+
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[encap_type]);
+	rcu_read_unlock();
+#ifdef CONFIG_MODULES
+	if (!ops) {
+		const char *encap_type_str = lwtunnel_encap_str(encap_type);
+
+		if (encap_type_str) {
+			__rtnl_unlock();
+			request_module("rtnl-lwt-%s", encap_type_str);
+			rtnl_lock();
+
+			rcu_read_lock();
+			ops = rcu_dereference(lwtun_encaps[encap_type]);
+			rcu_read_unlock();
+		}
+	}
+#endif
+	ret = ops ? 0 : -EOPNOTSUPP;
+	if (ret < 0)
+		NL_SET_ERR_MSG(extack, "lwt encapsulation type not supported");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type);
+
+int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining,
+				   struct netlink_ext_ack *extack)
+{
+	struct rtnexthop *rtnh = (struct rtnexthop *)attr;
+	struct nlattr *nla_entype;
+	struct nlattr *attrs;
+	u16 encap_type;
+	int attrlen;
+
+	while (rtnh_ok(rtnh, remaining)) {
+		attrlen = rtnh_attrlen(rtnh);
+		if (attrlen > 0) {
+			attrs = rtnh_attrs(rtnh);
+			nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
+
+			if (nla_entype) {
+				if (nla_len(nla_entype) < sizeof(u16)) {
+					NL_SET_ERR_MSG(extack, "Invalid RTA_ENCAP_TYPE");
+					return -EINVAL;
+				}
+				encap_type = nla_get_u16(nla_entype);
+
+				if (lwtunnel_valid_encap_type(encap_type,
+							      extack) != 0)
+					return -EOPNOTSUPP;
+			}
+		}
+		rtnh = rtnh_next(rtnh, &remaining);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type_attr);
+
+void lwtstate_free(struct lwtunnel_state *lws)
+{
+	const struct lwtunnel_encap_ops *ops = lwtun_encaps[lws->type];
+
+	if (ops->destroy_state) {
+		ops->destroy_state(lws);
+		kfree_rcu(lws, rcu);
+	} else {
+		kfree(lws);
+	}
+	module_put(ops->owner);
+}
+EXPORT_SYMBOL_GPL(lwtstate_free);
+
+int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
+			int encap_attr, int encap_type_attr)
+{
+	const struct lwtunnel_encap_ops *ops;
+	struct nlattr *nest;
+	int ret;
+
+	if (!lwtstate)
+		return 0;
+
+	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
+	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	nest = nla_nest_start_noflag(skb, encap_attr);
+	if (!nest)
+		return -EMSGSIZE;
+
+	ret = -EOPNOTSUPP;
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
+	if (likely(ops && ops->fill_encap))
+		ret = ops->fill_encap(skb, lwtstate);
+	rcu_read_unlock();
+
+	if (ret)
+		goto nla_put_failure;
+	nla_nest_end(skb, nest);
+	ret = nla_put_u16(skb, encap_type_attr, lwtstate->type);
+	if (ret)
+		goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+
+	return (ret == -EOPNOTSUPP ? 0 : ret);
+}
+EXPORT_SYMBOL_GPL(lwtunnel_fill_encap);
+
+int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
+{
+	const struct lwtunnel_encap_ops *ops;
+	int ret = 0;
+
+	if (!lwtstate)
+		return 0;
+
+	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
+	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
+	if (likely(ops && ops->get_encap_size))
+		ret = nla_total_size(ops->get_encap_size(lwtstate));
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_get_encap_size);
+
+int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
+{
+	const struct lwtunnel_encap_ops *ops;
+	int ret = 0;
+
+	if (!a && !b)
+		return 0;
+
+	if (!a || !b)
+		return 1;
+
+	if (a->type != b->type)
+		return 1;
+
+	if (a->type == LWTUNNEL_ENCAP_NONE ||
+	    a->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[a->type]);
+	if (likely(ops && ops->cmp_encap))
+		ret = ops->cmp_encap(a, b);
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_cmp_encap);
+
+int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	const struct lwtunnel_encap_ops *ops;
+	struct lwtunnel_state *lwtstate;
+	int ret = -EINVAL;
+
+	if (!dst)
+		goto drop;
+	lwtstate = dst->lwtstate;
+
+	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
+	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	ret = -EOPNOTSUPP;
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
+	if (likely(ops && ops->output))
+		ret = ops->output(net, sk, skb);
+	rcu_read_unlock();
+
+	if (ret == -EOPNOTSUPP)
+		goto drop;
+
+	return ret;
+
+drop:
+	kfree_skb(skb);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_output);
+
+int lwtunnel_xmit(struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	const struct lwtunnel_encap_ops *ops;
+	struct lwtunnel_state *lwtstate;
+	int ret = -EINVAL;
+
+	if (!dst)
+		goto drop;
+
+	lwtstate = dst->lwtstate;
+
+	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
+	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	ret = -EOPNOTSUPP;
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
+	if (likely(ops && ops->xmit))
+		ret = ops->xmit(skb);
+	rcu_read_unlock();
+
+	if (ret == -EOPNOTSUPP)
+		goto drop;
+
+	return ret;
+
+drop:
+	kfree_skb(skb);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_xmit);
+
+int lwtunnel_input(struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	const struct lwtunnel_encap_ops *ops;
+	struct lwtunnel_state *lwtstate;
+	int ret = -EINVAL;
+
+	if (!dst)
+		goto drop;
+	lwtstate = dst->lwtstate;
+
+	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
+	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	ret = -EOPNOTSUPP;
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
+	if (likely(ops && ops->input))
+		ret = ops->input(skb);
+	rcu_read_unlock();
+
+	if (ret == -EOPNOTSUPP)
+		goto drop;
+
+	return ret;
+
+drop:
+	kfree_skb(skb);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lwtunnel_input);