// 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; if (dev) dev_hold(dev); 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) { if (ops->gc(ops)) { pr_notice_ratelimited("Route cache is full: consider increasing sysctl net.ipv6.route.max_size.\n"); return NULL; } } 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); if (dst->dev) dev_put(dst->dev); 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; dev_hold(dst->dev); dev_put(dev); } 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);