// SPDX-License-Identifier: GPL-2.0-only
/*
* net/core/dst.c Protocol independent destination cache.
*
* Authors: Alexey Kuznetsov, <[email protected]>
*
*/
#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->__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->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);
}
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;
dst->obsolete = DST_OBSOLETE_DEAD;
if (dst->ops->ifdown)
dst->ops->ifdown(dst, dev);
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 && rcuref_put(&dst->__rcuref))
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_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, 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
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(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)
{
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);
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