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hc
2024-10-12 a5969cabbb4660eab42b6ef0412cbbd1200cf14d 
 kernel/net/core/dst.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * net/core/dst.c	Protocol independent destination cache.
34  *
....@@ -26,23 +27,6 @@
2627 #include <net/dst.h>
2728 #include <net/dst_metadata.h>
2829 
29
-/*
30
- * Theory of operations:
31
- * 1) We use a list, protected by a spinlock, to add
32
- *    new entries from both BH and non-BH context.
33
- * 2) In order to keep spinlock held for a small delay,
34
- *    we use a second list where are stored long lived
35
- *    entries, that are handled by the garbage collect thread
36
- *    fired by a workqueue.
37
- * 3) This list is guarded by a mutex,
38
- *    so that the gc_task and dst_dev_event() can be synchronized.
39
- */
40
-
41
-/*
42
- * We want to keep lock & list close together
43
- * to dirty as few cache lines as possible in __dst_free().
44
- * As this is not a very strong hint, we dont force an alignment on SMP.
45
- */
4630 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
4731 {
4832 	kfree_skb(skb);
....@@ -97,9 +81,13 @@
9781 {
9882 	struct dst_entry *dst;
9983 
100
-	if (ops->gc && dst_entries_get_fast(ops) > ops->gc_thresh) {
101
-		if (ops->gc(ops))
84
+	if (ops->gc &&
85
+	    !(flags & DST_NOCOUNT) &&
86
+	    dst_entries_get_fast(ops) > ops->gc_thresh) {
87
+		if (ops->gc(ops)) {
88
+			pr_notice_ratelimited("Route cache is full: consider increasing sysctl net.ipv6.route.max_size.\n");
10289 			return NULL;
90
+		}
10391 	}
10492 
10593 	dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
....@@ -156,7 +144,7 @@
156144 
157145 /* Operations to mark dst as DEAD and clean up the net device referenced
158146  * by dst:
159
- * 1. put the dst under loopback interface and discard all tx/rx packets
147
+ * 1. put the dst under blackhole interface and discard all tx/rx packets
160148  *    on this route.
161149  * 2. release the net_device
162150  * This function should be called when removing routes from the fib tree
....@@ -172,7 +160,7 @@
172160 		dst->ops->ifdown(dst, dev, true);
173161 	dst->input = dst_discard;
174162 	dst->output = dst_discard_out;
175
-	dst->dev = dev_net(dst->dev)->loopback_dev;
163
+	dst->dev = blackhole_netdev;
176164 	dev_hold(dst->dev);
177165 	dev_put(dev);
178166 }
....@@ -184,7 +172,7 @@
184172 		int newrefcnt;
185173 
186174 		newrefcnt = atomic_dec_return(&dst->__refcnt);
187
-		if (unlikely(newrefcnt < 0))
175
+		if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
188176 			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
189177 					     __func__, dst, newrefcnt);
190178 		if (!newrefcnt)
....@@ -199,7 +187,7 @@
199187 		int newrefcnt;
200188 
201189 		newrefcnt = atomic_dec_return(&dst->__refcnt);
202
-		if (unlikely(newrefcnt < 0))
190
+		if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
203191 			net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
204192 					     __func__, dst, newrefcnt);
205193 		if (!newrefcnt)
....@@ -249,37 +237,62 @@
249237 }
250238 EXPORT_SYMBOL(__dst_destroy_metrics_generic);
251239 
252
-static struct dst_ops md_dst_ops = {
253
-	.family =		AF_UNSPEC,
240
+struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie)
241
+{
242
+	return NULL;
243
+}
244
+
245
+u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old)
246
+{
247
+	return NULL;
248
+}
249
+
250
+struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst,
251
+					     struct sk_buff *skb,
252
+					     const void *daddr)
253
+{
254
+	return NULL;
255
+}
256
+
257
+void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
258
+			       struct sk_buff *skb, u32 mtu,
259
+			       bool confirm_neigh)
260
+{
261
+}
262
+EXPORT_SYMBOL_GPL(dst_blackhole_update_pmtu);
263
+
264
+void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
265
+			    struct sk_buff *skb)
266
+{
267
+}
268
+EXPORT_SYMBOL_GPL(dst_blackhole_redirect);
269
+
270
+unsigned int dst_blackhole_mtu(const struct dst_entry *dst)
271
+{
272
+	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
273
+
274
+	return mtu ? : dst->dev->mtu;
275
+}
276
+EXPORT_SYMBOL_GPL(dst_blackhole_mtu);
277
+
278
+static struct dst_ops dst_blackhole_ops = {
279
+	.family		= AF_UNSPEC,
280
+	.neigh_lookup	= dst_blackhole_neigh_lookup,
281
+	.check		= dst_blackhole_check,
282
+	.cow_metrics	= dst_blackhole_cow_metrics,
283
+	.update_pmtu	= dst_blackhole_update_pmtu,
284
+	.redirect	= dst_blackhole_redirect,
285
+	.mtu		= dst_blackhole_mtu,
254286 };
255
-
256
-static int dst_md_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
257
-{
258
-	WARN_ONCE(1, "Attempting to call output on metadata dst\n");
259
-	kfree_skb(skb);
260
-	return 0;
261
-}
262
-
263
-static int dst_md_discard(struct sk_buff *skb)
264
-{
265
-	WARN_ONCE(1, "Attempting to call input on metadata dst\n");
266
-	kfree_skb(skb);
267
-	return 0;
268
-}
269287 
270288 static void __metadata_dst_init(struct metadata_dst *md_dst,
271289 				enum metadata_type type, u8 optslen)
272
-
273290 {
274291 	struct dst_entry *dst;
275292 
276293 	dst = &md_dst->dst;
277
-	dst_init(dst, &md_dst_ops, NULL, 1, DST_OBSOLETE_NONE,
294
+	dst_init(dst, &dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE,
278295 		 DST_METADATA | DST_NOCOUNT);
279
-
280
-	dst->input = dst_md_discard;
281
-	dst->output = dst_md_discard_out;
282
-
283296 	memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst));
284297 	md_dst->type = type;
285298 }