Merge: net: introduce per netns packet chains

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6814

JIRA: https://issues.redhat.com/browse/RHEL-88921
Tested: vs issue reproducer

per netns packet chains prevent unrelated workload from interfering in different netns, causing incremental slow-down on each new tap.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Approved-by: Antoine Tenart <atenart@redhat.com>
Approved-by: Sabrina Dubroca <sdubroca@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

include/linux/netdevice.h

@@ -4191,7 +4191,17 @@ static __always_inline int ____dev_forward_skb(struct net_device *dev,
 	return 0;
 }
 
-bool dev_nit_active(struct net_device *dev);
+bool dev_nit_active_rcu(const struct net_device *dev);
+static inline bool dev_nit_active(const struct net_device *dev)
+{
+	bool ret;
+
+	rcu_read_lock();
+	ret = dev_nit_active_rcu(dev);
+	rcu_read_unlock();
+	return ret;
+}
+
 void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev);
 
 static inline void __dev_put(struct net_device *dev)

include/net/net_namespace.h

@@ -83,6 +83,9 @@ struct net {
 	struct llist_node	defer_free_list;
 	struct llist_node	cleanup_list;	/* namespaces on death row */
 
+	struct list_head ptype_all;
+	struct list_head ptype_specific;
+
 #ifdef CONFIG_KEYS
 	struct key_tag		*key_domain;	/* Key domain of operation tag */
 #endif

net/core/dev.c

@@ -164,7 +164,6 @@
 
 static DEFINE_SPINLOCK(ptype_lock);
 struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
-struct list_head ptype_all __read_mostly;	/* Taps */
 
 static int netif_rx_internal(struct sk_buff *skb);
 static int call_netdevice_notifiers_extack(unsigned long val,
@@ -569,10 +568,18 @@ static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
 
 static inline struct list_head *ptype_head(const struct packet_type *pt)
 {
-	if (pt->type == htons(ETH_P_ALL))
-		return pt->dev ? &pt->dev->ptype_all : &ptype_all;
-	else
-		return pt->dev ? &pt->dev->ptype_specific :
+	if (pt->type == htons(ETH_P_ALL)) {
+		if (!pt->af_packet_net && !pt->dev)
+			return NULL;
+
+		return pt->dev ? &pt->dev->ptype_all :
+				 &pt->af_packet_net->ptype_all;
+	}
+
+	if (pt->dev)
+		return &pt->dev->ptype_specific;
+
+	return pt->af_packet_net ? &pt->af_packet_net->ptype_specific :
 				 &ptype_base[ntohs(pt->type) & PTYPE_HASH_MASK];
 }
 
@@ -593,6 +600,9 @@ void dev_add_pack(struct packet_type *pt)
 {
 	struct list_head *head = ptype_head(pt);
 
+	if (WARN_ON_ONCE(!head))
+		return;
+
 	spin_lock(&ptype_lock);
 	list_add_rcu(&pt->list, head);
 	spin_unlock(&ptype_lock);
@@ -617,6 +627,9 @@ void __dev_remove_pack(struct packet_type *pt)
 	struct list_head *head = ptype_head(pt);
 	struct packet_type *pt1;
 
+	if (!head)
+		return;
+
 	spin_lock(&ptype_lock);
 
 	list_for_each_entry(pt1, head, list) {
@@ -2360,15 +2373,21 @@ static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb)
 }
 
 /**
- * dev_nit_active - return true if any network interface taps are in use
+ * dev_nit_active_rcu - return true if any network interface taps are in use
+ *
+ * The caller must hold the RCU lock
  *
  * @dev: network device to check for the presence of taps
  */
-bool dev_nit_active(struct net_device *dev)
+bool dev_nit_active_rcu(const struct net_device *dev)
 {
-	return !list_empty(&ptype_all) || !list_empty(&dev->ptype_all);
+	/* Callers may hold either RCU or RCU BH lock */
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
+
+	return !list_empty(&dev_net(dev)->ptype_all) ||
+	       !list_empty(&dev->ptype_all);
 }
-EXPORT_SYMBOL_GPL(dev_nit_active);
+EXPORT_SYMBOL_GPL(dev_nit_active_rcu);
 
 /*
  *	Support routine. Sends outgoing frames to any network
@@ -2380,9 +2399,10 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 	struct packet_type *ptype;
 	struct sk_buff *skb2 = NULL;
 	struct packet_type *pt_prev = NULL;
-	struct list_head *ptype_list = &ptype_all;
+	struct list_head *ptype_list;
 
 	rcu_read_lock();
+	ptype_list = &dev_net_rcu(dev)->ptype_all;
 again:
 	list_for_each_entry_rcu(ptype, ptype_list, list) {
 		if (READ_ONCE(ptype->ignore_outgoing))
@@ -2426,7 +2446,7 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 		pt_prev = ptype;
 	}
 
-	if (ptype_list == &ptype_all) {
+	if (ptype_list != &dev->ptype_all) {
 		ptype_list = &dev->ptype_all;
 		goto again;
 	}
@@ -3640,7 +3660,7 @@ static int xmit_one(struct sk_buff *skb, struct net_device *dev,
 	unsigned int len;
 	int rc;
 
-	if (dev_nit_active(dev))
+	if (dev_nit_active_rcu(dev))
 		dev_queue_xmit_nit(skb, dev);
 
 	len = skb->len;
@@ -5504,7 +5524,8 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
 	if (pfmemalloc)
 		goto skip_taps;
 
-	list_for_each_entry_rcu(ptype, &ptype_all, list) {
+	list_for_each_entry_rcu(ptype, &dev_net_rcu(skb->dev)->ptype_all,
+				list) {
 		if (pt_prev)
 			ret = deliver_skb(skb, pt_prev, orig_dev);
 		pt_prev = ptype;
@@ -5616,6 +5637,14 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
 		deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
 				       &ptype_base[ntohs(type) &
 						   PTYPE_HASH_MASK]);
+
+		/* orig_dev and skb->dev could belong to different netns;
+		 * Even in such case we need to traverse only the list
+		 * coming from skb->dev, as the ptype owner (packet socket)
+		 * will use dev_net(skb->dev) to do namespace filtering.
+		 */
+		deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
+				       &dev_net_rcu(skb->dev)->ptype_specific);
 	}
 
 	deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
@@ -12042,7 +12071,6 @@ static int __init net_dev_init(void)
 	if (netdev_kobject_init())
 		goto out;
 
-	INIT_LIST_HEAD(&ptype_all);
 	for (i = 0; i < PTYPE_HASH_SIZE; i++)
 		INIT_LIST_HEAD(&ptype_base[i]);
 

net/core/net-procfs.c

@@ -175,12 +175,18 @@ static void *ptype_get_idx(struct seq_file *seq, loff_t pos)
 		}
 	}
 
-	list_for_each_entry_rcu(pt, &ptype_all, list) {
+	list_for_each_entry_rcu(pt, &seq_file_net(seq)->ptype_all, list) {
 		if (i == pos)
 			return pt;
 		++i;
 	}
 
+	list_for_each_entry_rcu(pt, &seq_file_net(seq)->ptype_specific, list) {
+	if (i == pos)
+			return pt;
+		++i;
+	}
+
 	for (t = 0; t < PTYPE_HASH_SIZE; t++) {
 		list_for_each_entry_rcu(pt, &ptype_base[t], list) {
 			if (i == pos)
@@ -200,6 +206,7 @@ static void *ptype_seq_start(struct seq_file *seq, loff_t *pos)
 
 static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
+	struct net *net = seq_file_net(seq);
 	struct net_device *dev;
 	struct packet_type *pt;
 	struct list_head *nxt;
@@ -223,14 +230,22 @@ static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 			}
 		}
 
-		nxt = ptype_all.next;
-		goto ptype_all;
+		nxt = net->ptype_all.next;
+		goto net_ptype_all;
 	}
 
-	if (pt->type == htons(ETH_P_ALL)) {
-ptype_all:
-		if (nxt != &ptype_all)
+	if (pt->af_packet_net) {
+net_ptype_all:
+		if (nxt != &net->ptype_all && nxt != &net->ptype_specific)
 			goto found;
+
+		if (nxt == &net->ptype_all) {
+			/* continue with ->ptype_specific if it's not empty */
+			nxt = net->ptype_specific.next;
+			if (nxt != &net->ptype_specific)
+				goto found;
+		}
+
 		hash = 0;
 		nxt = ptype_base[0].next;
 	} else

net/core/net_namespace.c

@@ -311,6 +311,9 @@ EXPORT_SYMBOL_GPL(get_net_ns_by_id);
 static __net_init void preinit_net(struct net *net)
 {
 	ref_tracker_dir_init(&net->notrefcnt_tracker, 128, "net notrefcnt");
+
+	INIT_LIST_HEAD(&net->ptype_all);
+	INIT_LIST_HEAD(&net->ptype_specific);
 }
 
 /*