1 files changed, 351 insertions, 0 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
new file mode 100644
index 000000000..d178c5641
--- /dev/null
+++ b/net/core/dst.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * net/core/dst.c	Protocol independent destination cache.
+ *
+ * Authors:		Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/workqueue.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <net/net_namespace.h>
+#include <linux/sched.h>
+#include <linux/prefetch.h>
+#include <net/lwtunnel.h>
+#include <net/xfrm.h>
+
+#include <net/dst.h>
+#include <net/dst_metadata.h>
+
+int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	return 0;
+}
+EXPORT_SYMBOL(dst_discard_out);
+
+const struct dst_metrics dst_default_metrics = {
+	/* This initializer is needed to force linker to place this variable
+	 * into const section. Otherwise it might end into bss section.
+	 * We really want to avoid false sharing on this variable, and catch
+	 * any writes on it.
+	 */
+	.refcnt = REFCOUNT_INIT(1),
+};
+EXPORT_SYMBOL(dst_default_metrics);
+
+void dst_init(struct dst_entry *dst, struct dst_ops *ops,
+	      struct net_device *dev, int initial_ref, int initial_obsolete,
+	      unsigned short flags)
+{
+	dst->dev = dev;
+	netdev_hold(dev, &dst->dev_tracker, GFP_ATOMIC);
+	dst->ops = ops;
+	dst_init_metrics(dst, dst_default_metrics.metrics, true);
+	dst->expires = 0UL;
+#ifdef CONFIG_XFRM
+	dst->xfrm = NULL;
+#endif
+	dst->input = dst_discard;
+	dst->output = dst_discard_out;
+	dst->error = 0;
+	dst->obsolete = initial_obsolete;
+	dst->header_len = 0;
+	dst->trailer_len = 0;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	dst->tclassid = 0;
+#endif
+	dst->lwtstate = NULL;
+	atomic_set(&dst->__refcnt, initial_ref);
+	dst->__use = 0;
+	dst->lastuse = jiffies;
+	dst->flags = flags;
+	if (!(flags & DST_NOCOUNT))
+		dst_entries_add(ops, 1);
+}
+EXPORT_SYMBOL(dst_init);
+
+void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
+		int initial_ref, int initial_obsolete, unsigned short flags)
+{
+	struct dst_entry *dst;
+
+	if (ops->gc &&
+	    !(flags & DST_NOCOUNT) &&
+	    dst_entries_get_fast(ops) > ops->gc_thresh)
+		ops->gc(ops);
+
+	dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
+	if (!dst)
+		return NULL;
+
+	dst_init(dst, ops, dev, initial_ref, initial_obsolete, flags);
+
+	return dst;
+}
+EXPORT_SYMBOL(dst_alloc);
+
+struct dst_entry *dst_destroy(struct dst_entry * dst)
+{
+	struct dst_entry *child = NULL;
+
+	smp_rmb();
+
+#ifdef CONFIG_XFRM
+	if (dst->xfrm) {
+		struct xfrm_dst *xdst = (struct xfrm_dst *) dst;
+
+		child = xdst->child;
+	}
+#endif
+	if (!(dst->flags & DST_NOCOUNT))
+		dst_entries_add(dst->ops, -1);
+
+	if (dst->ops->destroy)
+		dst->ops->destroy(dst);
+	netdev_put(dst->dev, &dst->dev_tracker);
+
+	lwtstate_put(dst->lwtstate);
+
+	if (dst->flags & DST_METADATA)
+		metadata_dst_free((struct metadata_dst *)dst);
+	else
+		kmem_cache_free(dst->ops->kmem_cachep, dst);
+
+	dst = child;
+	if (dst)
+		dst_release_immediate(dst);
+	return NULL;
+}
+EXPORT_SYMBOL(dst_destroy);
+
+static void dst_destroy_rcu(struct rcu_head *head)
+{
+	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
+
+	dst = dst_destroy(dst);
+}
+
+/* Operations to mark dst as DEAD and clean up the net device referenced
+ * by dst:
+ * 1. put the dst under blackhole interface and discard all tx/rx packets
+ *    on this route.
+ * 2. release the net_device
+ * This function should be called when removing routes from the fib tree
+ * in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to
+ * make the next dst_ops->check() fail.
+ */
+void dst_dev_put(struct dst_entry *dst)
+{
+	struct net_device *dev = dst->dev;
+
+	dst->obsolete = DST_OBSOLETE_DEAD;
+	if (dst->ops->ifdown)
+		dst->ops->ifdown(dst, dev, true);
+	dst->input = dst_discard;
+	dst->output = dst_discard_out;
+	dst->dev = blackhole_netdev;
+	netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker,
+			   GFP_ATOMIC);
+}
+EXPORT_SYMBOL(dst_dev_put);
+
+void dst_release(struct dst_entry *dst)
+{
+	if (dst) {
+		int newrefcnt;
+
+		newrefcnt = atomic_dec_return(&dst->__refcnt);
+		if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
+			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
+					     __func__, dst, newrefcnt);
+		if (!newrefcnt)
+			call_rcu(&dst->rcu_head, dst_destroy_rcu);
+	}
+}
+EXPORT_SYMBOL(dst_release);
+
+void dst_release_immediate(struct dst_entry *dst)
+{
+	if (dst) {
+		int newrefcnt;
+
+		newrefcnt = atomic_dec_return(&dst->__refcnt);
+		if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
+			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
+					     __func__, dst, newrefcnt);
+		if (!newrefcnt)
+			dst_destroy(dst);
+	}
+}
+EXPORT_SYMBOL(dst_release_immediate);
+
+u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
+{
+	struct dst_metrics *p = kmalloc(sizeof(*p), GFP_ATOMIC);
+
+	if (p) {
+		struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old);
+		unsigned long prev, new;
+
+		refcount_set(&p->refcnt, 1);
+		memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));
+
+		new = (unsigned long) p;
+		prev = cmpxchg(&dst->_metrics, old, new);
+
+		if (prev != old) {
+			kfree(p);
+			p = (struct dst_metrics *)__DST_METRICS_PTR(prev);
+			if (prev & DST_METRICS_READ_ONLY)
+				p = NULL;
+		} else if (prev & DST_METRICS_REFCOUNTED) {
+			if (refcount_dec_and_test(&old_p->refcnt))
+				kfree(old_p);
+		}
+	}
+	BUILD_BUG_ON(offsetof(struct dst_metrics, metrics) != 0);
+	return (u32 *)p;
+}
+EXPORT_SYMBOL(dst_cow_metrics_generic);
+
+/* Caller asserts that dst_metrics_read_only(dst) is false.  */
+void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old)
+{
+	unsigned long prev, new;
+
+	new = ((unsigned long) &dst_default_metrics) | DST_METRICS_READ_ONLY;
+	prev = cmpxchg(&dst->_metrics, old, new);
+	if (prev == old)
+		kfree(__DST_METRICS_PTR(old));
+}
+EXPORT_SYMBOL(__dst_destroy_metrics_generic);
+
+struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie)
+{
+	return NULL;
+}
+
+u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old)
+{
+	return NULL;
+}
+
+struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst,
+					     struct sk_buff *skb,
+					     const void *daddr)
+{
+	return NULL;
+}
+
+void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
+			       struct sk_buff *skb, u32 mtu,
+			       bool confirm_neigh)
+{
+}
+EXPORT_SYMBOL_GPL(dst_blackhole_update_pmtu);
+
+void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
+			    struct sk_buff *skb)
+{
+}
+EXPORT_SYMBOL_GPL(dst_blackhole_redirect);
+
+unsigned int dst_blackhole_mtu(const struct dst_entry *dst)
+{
+	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
+
+	return mtu ? : dst->dev->mtu;
+}
+EXPORT_SYMBOL_GPL(dst_blackhole_mtu);
+
+static struct dst_ops dst_blackhole_ops = {
+	.family		= AF_UNSPEC,
+	.neigh_lookup	= dst_blackhole_neigh_lookup,
+	.check		= dst_blackhole_check,
+	.cow_metrics	= dst_blackhole_cow_metrics,
+	.update_pmtu	= dst_blackhole_update_pmtu,
+	.redirect	= dst_blackhole_redirect,
+	.mtu		= dst_blackhole_mtu,
+};
+
+static void __metadata_dst_init(struct metadata_dst *md_dst,
+				enum metadata_type type, u8 optslen)
+{
+	struct dst_entry *dst;
+
+	dst = &md_dst->dst;
+	dst_init(dst, &dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE,
+		 DST_METADATA | DST_NOCOUNT);
+	memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst));
+	md_dst->type = type;
+}
+
+struct metadata_dst *metadata_dst_alloc(u8 optslen, enum metadata_type type,
+					gfp_t flags)
+{
+	struct metadata_dst *md_dst;
+
+	md_dst = kmalloc(sizeof(*md_dst) + optslen, flags);
+	if (!md_dst)
+		return NULL;
+
+	__metadata_dst_init(md_dst, type, optslen);
+
+	return md_dst;
+}
+EXPORT_SYMBOL_GPL(metadata_dst_alloc);
+
+void metadata_dst_free(struct metadata_dst *md_dst)
+{
+#ifdef CONFIG_DST_CACHE
+	if (md_dst->type == METADATA_IP_TUNNEL)
+		dst_cache_destroy(&md_dst->u.tun_info.dst_cache);
+#endif
+	kfree(md_dst);
+}
+EXPORT_SYMBOL_GPL(metadata_dst_free);
+
+struct metadata_dst __percpu *
+metadata_dst_alloc_percpu(u8 optslen, enum metadata_type type, gfp_t flags)
+{
+	int cpu;
+	struct metadata_dst __percpu *md_dst;
+
+	md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen,
+				    __alignof__(struct metadata_dst), flags);
+	if (!md_dst)
+		return NULL;
+
+	for_each_possible_cpu(cpu)
+		__metadata_dst_init(per_cpu_ptr(md_dst, cpu), type, optslen);
+
+	return md_dst;
+}
+EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);
+
+void metadata_dst_free_percpu(struct metadata_dst __percpu *md_dst)
+{
+#ifdef CONFIG_DST_CACHE
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu);
+
+		if (one_md_dst->type == METADATA_IP_TUNNEL)
+			dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache);
+	}
+#endif
+	free_percpu(md_dst);
+}
+EXPORT_SYMBOL_GPL(metadata_dst_free_percpu);