// 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_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;	rcuref_init(&dst->__rcuref, 1);	INIT_LIST_HEAD(&dst->rt_uncached);	dst->rt_uncached_list = NULL;	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_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_obsolete, flags); 	return dst;}EXPORT_SYMBOL(dst_alloc); static void 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->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);} static void dst_destroy_rcu(struct rcu_head *head){	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 	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; 	WRITE_ONCE(dst->obsolete, DST_OBSOLETE_DEAD);	if (dst->ops->ifdown)		dst->ops->ifdown(dst, dev);	WRITE_ONCE(dst->input, dst_discard);	WRITE_ONCE(dst->output, dst_discard_out);	rcu_assign_pointer(dst->dev_rcu, blackhole_netdev);	netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker,			   GFP_ATOMIC);}EXPORT_SYMBOL(dst_dev_put); static void dst_count_dec(struct dst_entry *dst){	if (!(dst->flags & DST_NOCOUNT))		dst_entries_add(dst->ops, -1);} void dst_release(struct dst_entry *dst){	if (dst && rcuref_put(&dst->__rcuref)) {#ifdef CONFIG_DST_CACHE		if (dst->flags & DST_METADATA) {			struct metadata_dst *md_dst = (struct metadata_dst *)dst; 			if (md_dst->type == METADATA_IP_TUNNEL)				dst_cache_reset_now(&md_dst->u.tun_info.dst_cache);		}#endif		dst_count_dec(dst);		call_rcu_hurry(&dst->rcu_head, dst_destroy_rcu);	}}EXPORT_SYMBOL(dst_release); void dst_release_immediate(struct dst_entry *dst){	if (dst && rcuref_put(&dst->__rcuref)) {		dst_count_dec(dst);		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_obj(*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(dst)->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, 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_flex(*md_dst, u.tun_info.options, 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	if (md_dst->type == METADATA_XFRM)		dst_release(md_dst->u.xfrm_info.dst_orig);	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(struct_size(md_dst, u.tun_info.options,						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){	int cpu; 	for_each_possible_cpu(cpu) {		struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu); #ifdef CONFIG_DST_CACHE		if (one_md_dst->type == METADATA_IP_TUNNEL)			dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache);#endif		if (one_md_dst->type == METADATA_XFRM)			dst_release(one_md_dst->u.xfrm_info.dst_orig);	}	free_percpu(md_dst);}EXPORT_SYMBOL_GPL(metadata_dst_free_percpu);