Date: Mon,  6 May 2024 03:16:27 +0200
From: Antonio Quartulli <antonio@...nvpn.net>
To: netdev@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>,
	Sergey Ryazanov <ryazanov.s.a@...il.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Andrew Lunn <andrew@...n.ch>,
	Esben Haabendal <esben@...nix.com>,
	Antonio Quartulli <antonio@...nvpn.net>
Subject: [PATCH net-next v3 14/24] ovpn: implement multi-peer support

With this change an ovpn instance will be able to stay connected to
multiple remote endpoints.

This functionality is strictly required when running ovpn on an
OpenVPN server.

Signed-off-by: Antonio Quartulli <antonio@...nvpn.net>
---
 drivers/net/ovpn/io.c         |   1 +
 drivers/net/ovpn/main.c       |   8 +-
 drivers/net/ovpn/ovpnstruct.h |  10 +++
 drivers/net/ovpn/peer.c       | 149 ++++++++++++++++++++++++++++++++++
 drivers/net/ovpn/peer.h       |  14 ++++
 5 files changed, 181 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c
index 49efcfff963c..8ccf2700a370 100644
--- a/drivers/net/ovpn/io.c
+++ b/drivers/net/ovpn/io.c
@@ -36,6 +36,7 @@ int ovpn_struct_init(struct net_device *dev)
 		return err;
 
 	spin_lock_init(&ovpn->lock);
+	spin_lock_init(&ovpn->peers.lock);
 
 	ovpn->crypto_wq = alloc_workqueue("ovpn-crypto-wq-%s",
 					  WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 0,
diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c
index a04d6e55a473..d6ba91c6571f 100644
--- a/drivers/net/ovpn/main.c
+++ b/drivers/net/ovpn/main.c
@@ -176,8 +176,14 @@ void ovpn_iface_destruct(struct ovpn_struct *ovpn)
 
 	ovpn->registered = false;
 
-	if (ovpn->mode == OVPN_MODE_P2P)
+	switch (ovpn->mode) {
+	case OVPN_MODE_P2P:
 		ovpn_peer_release_p2p(ovpn);
+		break;
+	default:
+		ovpn_peers_free(ovpn);
+		break;
+	}
 
 	unregister_netdevice(ovpn->dev);
 	synchronize_net();
diff --git a/drivers/net/ovpn/ovpnstruct.h b/drivers/net/ovpn/ovpnstruct.h
index 7414c2459fb9..58166fdeac63 100644
--- a/drivers/net/ovpn/ovpnstruct.h
+++ b/drivers/net/ovpn/ovpnstruct.h
@@ -21,6 +21,10 @@
  * @crypto_wq: used to schedule crypto work that may sleep during TX/RX
  * @event_wq: used to schedule generic events that may sleep and that need to be
  *            performed outside of softirq context
+ * @peers.by_id: table of peers index by ID
+ * @peers.by_transp_addr: table of peers indexed by transport address
+ * @peers.by_vpn_addr: table of peers indexed by VPN IP address
+ * @peers.lock: protects writes to peers tables
  * @peer: in P2P mode, this is the only remote peer
  * @dev_list: entry for the module wide device list
  */
@@ -31,6 +35,12 @@ struct ovpn_struct {
 	spinlock_t lock; /* protect writing to the ovpn_struct object */
 	struct workqueue_struct *crypto_wq;
 	struct workqueue_struct *events_wq;
+	struct {
+		DECLARE_HASHTABLE(by_id, 12);
+		DECLARE_HASHTABLE(by_transp_addr, 12);
+		DECLARE_HASHTABLE(by_vpn_addr, 12);
+		spinlock_t lock; /* protects writes to peers tables */
+	} peers;
 	struct ovpn_peer __rcu *peer;
 	struct list_head dev_list;
 };
diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
index 99a2ae42a332..38a89595dade 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -9,6 +9,7 @@
 
 #include <linux/skbuff.h>
 #include <linux/list.h>
+#include <linux/hashtable.h>
 #include <linux/workqueue.h>
 
 #include "ovpnstruct.h"
@@ -361,6 +362,91 @@ struct ovpn_peer *ovpn_peer_get_by_src(struct ovpn_struct *ovpn,
 	return peer;
 }
 
+/**
+ * ovpn_peer_add_mp - add per to related tables in a MP instance
+ * @ovpn: the instance to add the peer to
+ * @peer: the peer to add
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+static int ovpn_peer_add_mp(struct ovpn_struct *ovpn, struct ovpn_peer *peer)
+{
+	struct sockaddr_storage sa = { 0 };
+	struct sockaddr_in6 *sa6;
+	struct sockaddr_in *sa4;
+	struct ovpn_bind *bind;
+	struct ovpn_peer *tmp;
+	size_t salen;
+	int ret = 0;
+	u32 index;
+
+	spin_lock_bh(&ovpn->peers.lock);
+	/* do not add duplicates */
+	tmp = ovpn_peer_get_by_id(ovpn, peer->id);
+	if (tmp) {
+		ovpn_peer_put(tmp);
+		ret = -EEXIST;
+		goto unlock;
+	}
+
+	hlist_del_init_rcu(&peer->hash_entry_transp_addr);
+	bind = rcu_dereference_protected(peer->bind, true);
+	/* peers connected via TCP have bind == NULL */
+	if (bind) {
+		switch (bind->sa.in4.sin_family) {
+		case AF_INET:
+			sa4 = (struct sockaddr_in *)&sa;
+
+			sa4->sin_family = AF_INET;
+			sa4->sin_addr.s_addr = bind->sa.in4.sin_addr.s_addr;
+			sa4->sin_port = bind->sa.in4.sin_port;
+			salen = sizeof(*sa4);
+			break;
+		case AF_INET6:
+			sa6 = (struct sockaddr_in6 *)&sa;
+
+			sa6->sin6_family = AF_INET6;
+			sa6->sin6_addr = bind->sa.in6.sin6_addr;
+			sa6->sin6_port = bind->sa.in6.sin6_port;
+			salen = sizeof(*sa6);
+			break;
+		default:
+			ret = -EPROTONOSUPPORT;
+			goto unlock;
+		}
+
+		index = ovpn_peer_index(ovpn->peers.by_transp_addr, &sa, salen);
+		hlist_add_head_rcu(&peer->hash_entry_transp_addr,
+				   &ovpn->peers.by_transp_addr[index]);
+	}
+
+	index = ovpn_peer_index(ovpn->peers.by_id, &peer->id, sizeof(peer->id));
+	hlist_add_head_rcu(&peer->hash_entry_id, &ovpn->peers.by_id[index]);
+
+	if (peer->vpn_addrs.ipv4.s_addr != htonl(INADDR_ANY)) {
+		index = ovpn_peer_index(ovpn->peers.by_vpn_addr,
+					&peer->vpn_addrs.ipv4,
+					sizeof(peer->vpn_addrs.ipv4));
+		hlist_add_head_rcu(&peer->hash_entry_addr4,
+				   &ovpn->peers.by_vpn_addr[index]);
+	}
+
+	hlist_del_init_rcu(&peer->hash_entry_addr6);
+	if (memcmp(&peer->vpn_addrs.ipv6, &in6addr_any,
+		   sizeof(peer->vpn_addrs.ipv6))) {
+		index = ovpn_peer_index(ovpn->peers.by_vpn_addr,
+					&peer->vpn_addrs.ipv6,
+					sizeof(peer->vpn_addrs.ipv6));
+		hlist_add_head_rcu(&peer->hash_entry_addr6,
+				   &ovpn->peers.by_vpn_addr[index]);
+	}
+
+unlock:
+	spin_unlock_bh(&ovpn->peers.lock);
+
+	return ret;
+}
+
 /**
  * ovpn_peer_add_p2p - add per to related tables in a P2P instance
  * @ovpn: the instance to add the peer to
@@ -391,6 +477,8 @@ static int ovpn_peer_add_p2p(struct ovpn_struct *ovpn, struct ovpn_peer *peer)
 int ovpn_peer_add(struct ovpn_struct *ovpn, struct ovpn_peer *peer)
 {
 	switch (ovpn->mode) {
+	case OVPN_MODE_MP:
+		return ovpn_peer_add_mp(ovpn, peer);
 	case OVPN_MODE_P2P:
 		return ovpn_peer_add_p2p(ovpn, peer);
 	default:
@@ -398,6 +486,53 @@ int ovpn_peer_add(struct ovpn_struct *ovpn, struct ovpn_peer *peer)
 	}
 }
 
+/**
+ * ovpn_peer_unhash - remove peer reference from all hashtables
+ * @peer: the peer to remove
+ * @reason: the delete reason to attach to the peer
+ */
+static void ovpn_peer_unhash(struct ovpn_peer *peer,
+			     enum ovpn_del_peer_reason reason)
+{
+	hlist_del_init_rcu(&peer->hash_entry_id);
+	hlist_del_init_rcu(&peer->hash_entry_addr4);
+	hlist_del_init_rcu(&peer->hash_entry_addr6);
+	hlist_del_init_rcu(&peer->hash_entry_transp_addr);
+
+	ovpn_peer_put(peer);
+	peer->delete_reason = reason;
+}
+
+/**
+ * ovpn_peer_del_mp - delete peer from related tables in a MP instance
+ * @peer: the peer to delete
+ * @reason: reason why the peer was deleted (sent to userspace)
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+static int ovpn_peer_del_mp(struct ovpn_peer *peer,
+			    enum ovpn_del_peer_reason reason)
+{
+	struct ovpn_peer *tmp;
+	int ret = 0;
+
+	spin_lock_bh(&peer->ovpn->peers.lock);
+	tmp = ovpn_peer_get_by_id(peer->ovpn, peer->id);
+	if (tmp != peer) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+	ovpn_peer_unhash(peer, reason);
+
+unlock:
+	spin_unlock_bh(&peer->ovpn->peers.lock);
+
+	if (tmp)
+		ovpn_peer_put(tmp);
+
+	return ret;
+}
+
 /**
  * ovpn_peer_del_p2p - delete peer from related tables in a P2P instance
  * @peer: the peer to delete
@@ -444,9 +579,23 @@ void ovpn_peer_release_p2p(struct ovpn_struct *ovpn)
 int ovpn_peer_del(struct ovpn_peer *peer, enum ovpn_del_peer_reason reason)
 {
 	switch (peer->ovpn->mode) {
+	case OVPN_MODE_MP:
+		return ovpn_peer_del_mp(peer, reason);
 	case OVPN_MODE_P2P:
 		return ovpn_peer_del_p2p(peer, reason);
 	default:
 		return -EOPNOTSUPP;
 	}
 }
+
+void ovpn_peers_free(struct ovpn_struct *ovpn)
+{
+	struct hlist_node *tmp;
+	struct ovpn_peer *peer;
+	int bkt;
+
+	spin_lock_bh(&ovpn->peers.lock);
+	hash_for_each_safe(ovpn->peers.by_id, bkt, tmp, peer, hash_entry_id)
+		ovpn_peer_unhash(peer, OVPN_DEL_PEER_REASON_TEARDOWN);
+	spin_unlock_bh(&ovpn->peers.lock);
+}
diff --git a/drivers/net/ovpn/peer.h b/drivers/net/ovpn/peer.h
index ac4907705d98..10f4153f7c8f 100644
--- a/drivers/net/ovpn/peer.h
+++ b/drivers/net/ovpn/peer.h
@@ -26,6 +26,10 @@
  * @id: unique identifier
  * @vpn_addrs.ipv4: IPv4 assigned to peer on the tunnel
  * @vpn_addrs.ipv6: IPv6 assigned to peer on the tunnel
+ * @hash_entry_id: entry in the peer ID hashtable
+ * @hash_entry_addr4: entry in the peer IPv4 hashtable
+ * @hash_entry_addr6: entry in the peer IPv6 hashtable
+ * @hash_entry_transp_addr: entry in the peer transport address hashtable
  * @encrypt_work: work used to process outgoing packets
  * @decrypt_work: work used to process incoming packets
  * @tx_ring: queue of outgoing poackets to this peer
@@ -62,6 +66,10 @@ struct ovpn_peer {
 		struct in_addr ipv4;
 		struct in6_addr ipv6;
 	} vpn_addrs;
+	struct hlist_node hash_entry_id;
+	struct hlist_node hash_entry_addr4;
+	struct hlist_node hash_entry_addr6;
+	struct hlist_node hash_entry_transp_addr;
 	struct work_struct encrypt_work;
 	struct work_struct decrypt_work;
 	struct ptr_ring tx_ring;
@@ -208,4 +216,10 @@ struct ovpn_peer *ovpn_peer_get_by_dst(struct ovpn_struct *ovpn,
 struct ovpn_peer *ovpn_peer_get_by_src(struct ovpn_struct *ovpn,
 				       struct sk_buff *skb);
 
+/**
+ * ovpn_peers_free - free all peers in the instance
+ * @ovpn: the instance whose peers should be released
+ */
+void ovpn_peers_free(struct ovpn_struct *ovpn);
+
 #endif /* _NET_OVPN_OVPNPEER_H_ */
-- 
2.43.2

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