Merge tag 'net-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Paolo Abeni:
 "Core:

   - Implement the Device Memory TCP transmit path, allowing zero-copy
     data transmission on top of TCP from e.g. GPU memory to the wire.

   - Move all the IPv6 routing tables management outside the RTNL scope,
     under its own lock and RCU. The route control path is now 3x times
     faster.

   - Convert queue related netlink ops to instance lock, reducing again
     the scope of the RTNL lock. This improves the control plane
     scalability.

   - Refactor the software crc32c implementation, removing unneeded
     abstraction layers and improving significantly the related
     micro-benchmarks.

   - Optimize the GRO engine for UDP-tunneled traffic, for a 10%
     performance improvement in related stream tests.

   - Cover more per-CPU storage with local nested BH locking; this is a
     prep work to remove the current per-CPU lock in local_bh_disable()
     on PREMPT_RT.

   - Introduce and use nlmsg_payload helper, combining buffer bounds
     verification with accessing payload carried by netlink messages.

  Netfilter:

   - Rewrite the procfs conntrack table implementation, improving
     considerably the dump performance. A lot of user-space tools still
     use this interface.

   - Implement support for wildcard netdevice in netdev basechain and
     flowtables.

   - Integrate conntrack information into nft trace infrastructure.

   - Export set count and backend name to userspace, for better
     introspection.

  BPF:

   - BPF qdisc support: BPF-qdisc can be implemented with BPF struct_ops
     programs and can be controlled in similar way to traditional qdiscs
     using the "tc qdisc" command.

   - Refactor the UDP socket iterator, addressing long standing issues
     WRT duplicate hits or missed sockets.

  Protocols:

   - Improve TCP receive buffer auto-tuning and increase the default
     upper bound for the receive buffer; overall this improves the
     single flow maximum thoughput on 200Gbs link by over 60%.

   - Add AFS GSSAPI security class to AF_RXRPC; it provides transport
     security for connections to the AFS fileserver and VL server.

   - Improve TCP multipath routing, so that the sources address always
     matches the nexthop device.

   - Introduce SO_PASSRIGHTS for AF_UNIX, to allow disabling SCM_RIGHTS,
     and thus preventing DoS caused by passing around problematic FDs.

   - Retire DCCP socket. DCCP only receives updates for bugs, and major
     distros disable it by default. Its removal allows for better
     organisation of TCP fields to reduce the number of cache lines hit
     in the fast path.

   - Extend TCP drop-reason support to cover PAWS checks.

  Driver API:

   - Reorganize PTP ioctl flag support to require an explicit opt-in for
     the drivers, avoiding the problem of drivers not rejecting new
     unsupported flags.

   - Converted several device drivers to timestamping APIs.

   - Introduce per-PHY ethtool dump helpers, improving the support for
     dump operations targeting PHYs.

  Tests and tooling:

   - Add support for classic netlink in user space C codegen, so that
     ynl-c can now read, create and modify links, routes addresses and
     qdisc layer configuration.

   - Add ynl sub-types for binary attributes, allowing ynl-c to output
     known struct instead of raw binary data, clarifying the classic
     netlink output.

   - Extend MPTCP selftests to improve the code-coverage.

   - Add tests for XDP tail adjustment in AF_XDP.

  New hardware / drivers:

   - OpenVPN virtual driver: offload OpenVPN data channels processing to
     the kernel-space, increasing the data transfer throughput WRT the
     user-space implementation.

   - Renesas glue driver for the gigabit ethernet RZ/V2H(P) SoC.

   - Broadcom asp-v3.0 ethernet driver.

   - AMD Renoir ethernet device.

   - ReakTek MT9888 2.5G ethernet PHY driver.

   - Aeonsemi 10G C45 PHYs driver.

  Drivers:

   - Ethernet high-speed NICs:
       - nVidia/Mellanox (mlx5):
           - refactor the steering table handling to significantly
             reduce the amount of memory used
           - add support for complex matches in H/W flow steering
           - improve flow streeing error handling
           - convert to netdev instance locking
       - Intel (100G, ice, igb, ixgbe, idpf):
           - ice: add switchdev support for LLDP traffic over VF
           - ixgbe: add firmware manipulation and regions devlink support
           - igb: introduce support for frame transmission premption
           - igb: adds persistent NAPI configuration
           - idpf: introduce RDMA support
           - idpf: add initial PTP support
       - Meta (fbnic):
           - extend hardware stats coverage
           - add devlink dev flash support
       - Broadcom (bnxt):
           - add support for RX-side device memory TCP
       - Wangxun (txgbe):
           - implement support for udp tunnel offload
           - complete PTP and SRIOV support for AML 25G/10G devices

   - Ethernet NICs embedded and virtual:
       - Google (gve):
           - add device memory TCP TX support
       - Amazon (ena):
           - support persistent per-NAPI config
       - Airoha:
           - add H/W support for L2 traffic offload
           - add per flow stats for flow offloading
       - RealTek (rtl8211): add support for WoL magic packet
       - Synopsys (stmmac):
           - dwmac-socfpga 1000BaseX support
           - add Loongson-2K3000 support
           - introduce support for hardware-accelerated VLAN stripping
       - Broadcom (bcmgenet):
           - expose more H/W stats
       - Freescale (enetc, dpaa2-eth):
           - enetc: add MAC filter, VLAN filter RSS and loopback support
           - dpaa2-eth: convert to H/W timestamping APIs
       - vxlan: convert FDB table to rhashtable, for better scalabilty
       - veth: apply qdisc backpressure on full ring to reduce TX drops

   - Ethernet switches:
       - Microchip (kzZ88x3): add ETS scheduler support

   - Ethernet PHYs:
       - RealTek (rtl8211):
           - add support for WoL magic packet
           - add support for PHY LEDs

   - CAN:
       - Adds RZ/G3E CANFD support to the rcar_canfd driver.
       - Preparatory work for CAN-XL support.
       - Add self-tests framework with support for CAN physical interfaces.

   - WiFi:
       - mac80211:
           - scan improvements with multi-link operation (MLO)
       - Qualcomm (ath12k):
           - enable AHB support for IPQ5332
           - add monitor interface support to QCN9274
           - add multi-link operation support to WCN7850
           - add 802.11d scan offload support to WCN7850
           - monitor mode for WCN7850, better 6 GHz regulatory
       - Qualcomm (ath11k):
           - restore hibernation support
       - MediaTek (mt76):
           - WiFi-7 improvements
           - implement support for mt7990
       - Intel (iwlwifi):
           - enhanced multi-link single-radio (EMLSR) support on 5 GHz links
           - rework device configuration
       - RealTek (rtw88):
           - improve throughput for RTL8814AU
       - RealTek (rtw89):
           - add multi-link operation support
           - STA/P2P concurrency improvements
           - support different SAR configs by antenna

   - Bluetooth:
       - introduce HCI Driver protocol
       - btintel_pcie: do not generate coredump for diagnostic events
       - btusb: add HCI Drv commands for configuring altsetting
       - btusb: add RTL8851BE device 0x0bda:0xb850
       - btusb: add new VID/PID 13d3/3584 for MT7922
       - btusb: add new VID/PID 13d3/3630 and 13d3/3613 for MT7925
       - btnxpuart: implement host-wakeup feature"

* tag 'net-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1611 commits)
  selftests/bpf: Fix bpf selftest build warning
  selftests: netfilter: Fix skip of wildcard interface test
  net: phy: mscc: Stop clearing the the UDPv4 checksum for L2 frames
  net: openvswitch: Fix the dead loop of MPLS parse
  calipso: Don't call calipso functions for AF_INET sk.
  selftests/tc-testing: Add a test for HFSC eltree double add with reentrant enqueue behaviour on netem
  net_sched: hfsc: Address reentrant enqueue adding class to eltree twice
  octeontx2-pf: QOS: Refactor TC_HTB_LEAF_DEL_LAST callback
  octeontx2-pf: QOS: Perform cache sync on send queue teardown
  net: mana: Add support for Multi Vports on Bare metal
  net: devmem: ncdevmem: remove unused variable
  net: devmem: ksft: upgrade rx test to send 1K data
  net: devmem: ksft: add 5 tuple FS support
  net: devmem: ksft: add exit_wait to make rx test pass
  net: devmem: ksft: add ipv4 support
  net: devmem: preserve sockc_err
  page_pool: fix ugly page_pool formatting
  net: devmem: move list_add to net_devmem_bind_dmabuf.
  selftests: netfilter: nft_queue.sh: include file transfer duration in log message
  net: phy: mscc: Fix memory leak when using one step timestamping
  ...

1 files changed, 1364 insertions, 0 deletions

diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
new file mode 100644
index 000000000000..a1fd27b9c038
--- /dev/null
+++ b/drivers/net/ovpn/peer.c
@@ -0,0 +1,1364 @@
+// SPDX-License-Identifier: GPL-2.0
+/*  OpenVPN data channel offload
+ *
+ *  Copyright (C) 2020-2025 OpenVPN, Inc.
+ *
+ *  Author:	James Yonan <[email protected]>
+ *		Antonio Quartulli <[email protected]>
+ */
+
+#include <linux/skbuff.h>
+#include <linux/list.h>
+#include <linux/hashtable.h>
+#include <net/ip6_route.h>
+
+#include "ovpnpriv.h"
+#include "bind.h"
+#include "pktid.h"
+#include "crypto.h"
+#include "io.h"
+#include "main.h"
+#include "netlink.h"
+#include "peer.h"
+#include "socket.h"
+
+static void unlock_ovpn(struct ovpn_priv *ovpn,
+			 struct llist_head *release_list)
+	__releases(&ovpn->lock)
+{
+	struct ovpn_peer *peer;
+
+	spin_unlock_bh(&ovpn->lock);
+
+	llist_for_each_entry(peer, release_list->first, release_entry) {
+		ovpn_socket_release(peer);
+		ovpn_peer_put(peer);
+	}
+}
+
+/**
+ * ovpn_peer_keepalive_set - configure keepalive values for peer
+ * @peer: the peer to configure
+ * @interval: outgoing keepalive interval
+ * @timeout: incoming keepalive timeout
+ */
+void ovpn_peer_keepalive_set(struct ovpn_peer *peer, u32 interval, u32 timeout)
+{
+	time64_t now = ktime_get_real_seconds();
+
+	netdev_dbg(peer->ovpn->dev,
+		   "scheduling keepalive for peer %u: interval=%u timeout=%u\n",
+		   peer->id, interval, timeout);
+
+	peer->keepalive_interval = interval;
+	WRITE_ONCE(peer->last_sent, now);
+	peer->keepalive_xmit_exp = now + interval;
+
+	peer->keepalive_timeout = timeout;
+	WRITE_ONCE(peer->last_recv, now);
+	peer->keepalive_recv_exp = now + timeout;
+
+	/* now that interval and timeout have been changed, kick
+	 * off the worker so that the next delay can be recomputed
+	 */
+	mod_delayed_work(system_wq, &peer->ovpn->keepalive_work, 0);
+}
+
+/**
+ * ovpn_peer_keepalive_send - periodic worker sending keepalive packets
+ * @work: pointer to the work member of the related peer object
+ *
+ * NOTE: the reference to peer is not dropped because it gets inherited
+ * by ovpn_xmit_special()
+ */
+static void ovpn_peer_keepalive_send(struct work_struct *work)
+{
+	struct ovpn_peer *peer = container_of(work, struct ovpn_peer,
+					      keepalive_work);
+
+	local_bh_disable();
+	ovpn_xmit_special(peer, ovpn_keepalive_message,
+			  sizeof(ovpn_keepalive_message));
+	local_bh_enable();
+}
+
+/**
+ * ovpn_peer_new - allocate and initialize a new peer object
+ * @ovpn: the openvpn instance inside which the peer should be created
+ * @id: the ID assigned to this peer
+ *
+ * Return: a pointer to the new peer on success or an error code otherwise
+ */
+struct ovpn_peer *ovpn_peer_new(struct ovpn_priv *ovpn, u32 id)
+{
+	struct ovpn_peer *peer;
+	int ret;
+
+	/* alloc and init peer object */
+	peer = kzalloc(sizeof(*peer), GFP_KERNEL);
+	if (!peer)
+		return ERR_PTR(-ENOMEM);
+
+	peer->id = id;
+	peer->ovpn = ovpn;
+
+	peer->vpn_addrs.ipv4.s_addr = htonl(INADDR_ANY);
+	peer->vpn_addrs.ipv6 = in6addr_any;
+
+	RCU_INIT_POINTER(peer->bind, NULL);
+	ovpn_crypto_state_init(&peer->crypto);
+	spin_lock_init(&peer->lock);
+	kref_init(&peer->refcount);
+	ovpn_peer_stats_init(&peer->vpn_stats);
+	ovpn_peer_stats_init(&peer->link_stats);
+	INIT_WORK(&peer->keepalive_work, ovpn_peer_keepalive_send);
+
+	ret = dst_cache_init(&peer->dst_cache, GFP_KERNEL);
+	if (ret < 0) {
+		netdev_err(ovpn->dev,
+			   "cannot initialize dst cache for peer %u\n",
+			   peer->id);
+		kfree(peer);
+		return ERR_PTR(ret);
+	}
+
+	netdev_hold(ovpn->dev, &peer->dev_tracker, GFP_KERNEL);
+
+	return peer;
+}
+
+/**
+ * ovpn_peer_reset_sockaddr - recreate binding for peer
+ * @peer: peer to recreate the binding for
+ * @ss: sockaddr to use as remote endpoint for the binding
+ * @local_ip: local IP for the binding
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+int ovpn_peer_reset_sockaddr(struct ovpn_peer *peer,
+			     const struct sockaddr_storage *ss,
+			     const void *local_ip)
+{
+	struct ovpn_bind *bind;
+	size_t ip_len;
+
+	lockdep_assert_held(&peer->lock);
+
+	/* create new ovpn_bind object */
+	bind = ovpn_bind_from_sockaddr(ss);
+	if (IS_ERR(bind))
+		return PTR_ERR(bind);
+
+	if (local_ip) {
+		if (ss->ss_family == AF_INET) {
+			ip_len = sizeof(struct in_addr);
+		} else if (ss->ss_family == AF_INET6) {
+			ip_len = sizeof(struct in6_addr);
+		} else {
+			net_dbg_ratelimited("%s: invalid family %u for remote endpoint for peer %u\n",
+					    netdev_name(peer->ovpn->dev),
+					    ss->ss_family, peer->id);
+			kfree(bind);
+			return -EINVAL;
+		}
+
+		memcpy(&bind->local, local_ip, ip_len);
+	}
+
+	/* set binding */
+	ovpn_bind_reset(peer, bind);
+
+	return 0;
+}
+
+/* variable name __tbl2 needs to be different from __tbl1
+ * in the macro below to avoid confusing clang
+ */
+#define ovpn_get_hash_slot(_tbl, _key, _key_len) ({	\
+	typeof(_tbl) *__tbl2 = &(_tbl);			\
+	jhash(_key, _key_len, 0) % HASH_SIZE(*__tbl2);	\
+})
+
+#define ovpn_get_hash_head(_tbl, _key, _key_len) ({		\
+	typeof(_tbl) *__tbl1 = &(_tbl);				\
+	&(*__tbl1)[ovpn_get_hash_slot(*__tbl1, _key, _key_len)];\
+})
+
+/**
+ * ovpn_peer_endpoints_update - update remote or local endpoint for peer
+ * @peer: peer to update the remote endpoint for
+ * @skb: incoming packet to retrieve the source/destination address from
+ */
+void ovpn_peer_endpoints_update(struct ovpn_peer *peer, struct sk_buff *skb)
+{
+	struct hlist_nulls_head *nhead;
+	struct sockaddr_storage ss;
+	struct sockaddr_in6 *sa6;
+	bool reset_cache = false;
+	struct sockaddr_in *sa;
+	struct ovpn_bind *bind;
+	const void *local_ip;
+	size_t salen = 0;
+
+	spin_lock_bh(&peer->lock);
+	bind = rcu_dereference_protected(peer->bind,
+					 lockdep_is_held(&peer->lock));
+	if (unlikely(!bind))
+		goto unlock;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		/* float check */
+		if (unlikely(!ovpn_bind_skb_src_match(bind, skb))) {
+			/* unconditionally save local endpoint in case
+			 * of float, as it may have changed as well
+			 */
+			local_ip = &ip_hdr(skb)->daddr;
+			sa = (struct sockaddr_in *)&ss;
+			sa->sin_family = AF_INET;
+			sa->sin_addr.s_addr = ip_hdr(skb)->saddr;
+			sa->sin_port = udp_hdr(skb)->source;
+			salen = sizeof(*sa);
+			reset_cache = true;
+			break;
+		}
+
+		/* if no float happened, let's double check if the local endpoint
+		 * has changed
+		 */
+		if (unlikely(bind->local.ipv4.s_addr != ip_hdr(skb)->daddr)) {
+			net_dbg_ratelimited("%s: learning local IPv4 for peer %d (%pI4 -> %pI4)\n",
+					    netdev_name(peer->ovpn->dev),
+					    peer->id, &bind->local.ipv4.s_addr,
+					    &ip_hdr(skb)->daddr);
+			bind->local.ipv4.s_addr = ip_hdr(skb)->daddr;
+			reset_cache = true;
+		}
+		break;
+	case htons(ETH_P_IPV6):
+		/* float check */
+		if (unlikely(!ovpn_bind_skb_src_match(bind, skb))) {
+			/* unconditionally save local endpoint in case
+			 * of float, as it may have changed as well
+			 */
+			local_ip = &ipv6_hdr(skb)->daddr;
+			sa6 = (struct sockaddr_in6 *)&ss;
+			sa6->sin6_family = AF_INET6;
+			sa6->sin6_addr = ipv6_hdr(skb)->saddr;
+			sa6->sin6_port = udp_hdr(skb)->source;
+			sa6->sin6_scope_id = ipv6_iface_scope_id(&ipv6_hdr(skb)->saddr,
+								 skb->skb_iif);
+			salen = sizeof(*sa6);
+			reset_cache = true;
+			break;
+		}
+
+		/* if no float happened, let's double check if the local endpoint
+		 * has changed
+		 */
+		if (unlikely(!ipv6_addr_equal(&bind->local.ipv6,
+					      &ipv6_hdr(skb)->daddr))) {
+			net_dbg_ratelimited("%s: learning local IPv6 for peer %d (%pI6c -> %pI6c)\n",
+					    netdev_name(peer->ovpn->dev),
+					    peer->id, &bind->local.ipv6,
+					    &ipv6_hdr(skb)->daddr);
+			bind->local.ipv6 = ipv6_hdr(skb)->daddr;
+			reset_cache = true;
+		}
+		break;
+	default:
+		goto unlock;
+	}
+
+	if (unlikely(reset_cache))
+		dst_cache_reset(&peer->dst_cache);
+
+	/* if the peer did not float, we can bail out now */
+	if (likely(!salen))
+		goto unlock;
+
+	if (unlikely(ovpn_peer_reset_sockaddr(peer,
+					      (struct sockaddr_storage *)&ss,
+					      local_ip) < 0))
+		goto unlock;
+
+	net_dbg_ratelimited("%s: peer %d floated to %pIScp",
+			    netdev_name(peer->ovpn->dev), peer->id, &ss);
+
+	spin_unlock_bh(&peer->lock);
+
+	/* rehashing is required only in MP mode as P2P has one peer
+	 * only and thus there is no hashtable
+	 */
+	if (peer->ovpn->mode == OVPN_MODE_MP) {
+		spin_lock_bh(&peer->ovpn->lock);
+		spin_lock_bh(&peer->lock);
+		bind = rcu_dereference_protected(peer->bind,
+						 lockdep_is_held(&peer->lock));
+		if (unlikely(!bind)) {
+			spin_unlock_bh(&peer->lock);
+			spin_unlock_bh(&peer->ovpn->lock);
+			return;
+		}
+
+		/* This function may be invoked concurrently, therefore another
+		 * float may have happened in parallel: perform rehashing
+		 * using the peer->bind->remote directly as key
+		 */
+
+		switch (bind->remote.in4.sin_family) {
+		case AF_INET:
+			salen = sizeof(*sa);
+			break;
+		case AF_INET6:
+			salen = sizeof(*sa6);
+			break;
+		}
+
+		/* remove old hashing */
+		hlist_nulls_del_init_rcu(&peer->hash_entry_transp_addr);
+		/* re-add with new transport address */
+		nhead = ovpn_get_hash_head(peer->ovpn->peers->by_transp_addr,
+					   &bind->remote, salen);
+		hlist_nulls_add_head_rcu(&peer->hash_entry_transp_addr, nhead);
+		spin_unlock_bh(&peer->lock);
+		spin_unlock_bh(&peer->ovpn->lock);
+	}
+	return;
+unlock:
+	spin_unlock_bh(&peer->lock);
+}
+
+/**
+ * ovpn_peer_release_rcu - RCU callback performing last peer release steps
+ * @head: RCU member of the ovpn_peer
+ */
+static void ovpn_peer_release_rcu(struct rcu_head *head)
+{
+	struct ovpn_peer *peer = container_of(head, struct ovpn_peer, rcu);
+
+	/* this call will immediately free the dst_cache, therefore we
+	 * perform it in the RCU callback, when all contexts are done
+	 */
+	dst_cache_destroy(&peer->dst_cache);
+	kfree(peer);
+}
+
+/**
+ * ovpn_peer_release - release peer private members
+ * @peer: the peer to release
+ */
+void ovpn_peer_release(struct ovpn_peer *peer)
+{
+	ovpn_crypto_state_release(&peer->crypto);
+	spin_lock_bh(&peer->lock);
+	ovpn_bind_reset(peer, NULL);
+	spin_unlock_bh(&peer->lock);
+	call_rcu(&peer->rcu, ovpn_peer_release_rcu);
+	netdev_put(peer->ovpn->dev, &peer->dev_tracker);
+}
+
+/**
+ * ovpn_peer_release_kref - callback for kref_put
+ * @kref: the kref object belonging to the peer
+ */
+void ovpn_peer_release_kref(struct kref *kref)
+{
+	struct ovpn_peer *peer = container_of(kref, struct ovpn_peer, refcount);
+
+	ovpn_peer_release(peer);
+}
+
+/**
+ * ovpn_peer_skb_to_sockaddr - fill sockaddr with skb source address
+ * @skb: the packet to extract data from
+ * @ss: the sockaddr to fill
+ *
+ * Return: sockaddr length on success or -1 otherwise
+ */
+static int ovpn_peer_skb_to_sockaddr(struct sk_buff *skb,
+				     struct sockaddr_storage *ss)
+{
+	struct sockaddr_in6 *sa6;
+	struct sockaddr_in *sa4;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		sa4 = (struct sockaddr_in *)ss;
+		sa4->sin_family = AF_INET;
+		sa4->sin_addr.s_addr = ip_hdr(skb)->saddr;
+		sa4->sin_port = udp_hdr(skb)->source;
+		return sizeof(*sa4);
+	case htons(ETH_P_IPV6):
+		sa6 = (struct sockaddr_in6 *)ss;
+		sa6->sin6_family = AF_INET6;
+		sa6->sin6_addr = ipv6_hdr(skb)->saddr;
+		sa6->sin6_port = udp_hdr(skb)->source;
+		return sizeof(*sa6);
+	}
+
+	return -1;
+}
+
+/**
+ * ovpn_nexthop_from_skb4 - retrieve IPv4 nexthop for outgoing skb
+ * @skb: the outgoing packet
+ *
+ * Return: the IPv4 of the nexthop
+ */
+static __be32 ovpn_nexthop_from_skb4(struct sk_buff *skb)
+{
+	const struct rtable *rt = skb_rtable(skb);
+
+	if (rt && rt->rt_uses_gateway)
+		return rt->rt_gw4;
+
+	return ip_hdr(skb)->daddr;
+}
+
+/**
+ * ovpn_nexthop_from_skb6 - retrieve IPv6 nexthop for outgoing skb
+ * @skb: the outgoing packet
+ *
+ * Return: the IPv6 of the nexthop
+ */
+static struct in6_addr ovpn_nexthop_from_skb6(struct sk_buff *skb)
+{
+	const struct rt6_info *rt = skb_rt6_info(skb);
+
+	if (!rt || !(rt->rt6i_flags & RTF_GATEWAY))
+		return ipv6_hdr(skb)->daddr;
+
+	return rt->rt6i_gateway;
+}
+
+/**
+ * ovpn_peer_get_by_vpn_addr4 - retrieve peer by its VPN IPv4 address
+ * @ovpn: the openvpn instance to search
+ * @addr: VPN IPv4 to use as search key
+ *
+ * Refcounter is not increased for the returned peer.
+ *
+ * Return: the peer if found or NULL otherwise
+ */
+static struct ovpn_peer *ovpn_peer_get_by_vpn_addr4(struct ovpn_priv *ovpn,
+						    __be32 addr)
+{
+	struct hlist_nulls_head *nhead;
+	struct hlist_nulls_node *ntmp;
+	struct ovpn_peer *tmp;
+	unsigned int slot;
+
+begin:
+	slot = ovpn_get_hash_slot(ovpn->peers->by_vpn_addr4, &addr,
+				  sizeof(addr));
+	nhead = &ovpn->peers->by_vpn_addr4[slot];
+
+	hlist_nulls_for_each_entry_rcu(tmp, ntmp, nhead, hash_entry_addr4)
+		if (addr == tmp->vpn_addrs.ipv4.s_addr)
+			return tmp;
+
+	/* item may have moved during lookup - check nulls and restart
+	 * if that's the case
+	 */
+	if (get_nulls_value(ntmp) != slot)
+		goto begin;
+
+	return NULL;
+}
+
+/**
+ * ovpn_peer_get_by_vpn_addr6 - retrieve peer by its VPN IPv6 address
+ * @ovpn: the openvpn instance to search
+ * @addr: VPN IPv6 to use as search key
+ *
+ * Refcounter is not increased for the returned peer.
+ *
+ * Return: the peer if found or NULL otherwise
+ */
+static struct ovpn_peer *ovpn_peer_get_by_vpn_addr6(struct ovpn_priv *ovpn,
+						    struct in6_addr *addr)
+{
+	struct hlist_nulls_head *nhead;
+	struct hlist_nulls_node *ntmp;
+	struct ovpn_peer *tmp;
+	unsigned int slot;
+
+begin:
+	slot = ovpn_get_hash_slot(ovpn->peers->by_vpn_addr6, addr,
+				  sizeof(*addr));
+	nhead = &ovpn->peers->by_vpn_addr6[slot];
+
+	hlist_nulls_for_each_entry_rcu(tmp, ntmp, nhead, hash_entry_addr6)
+		if (ipv6_addr_equal(addr, &tmp->vpn_addrs.ipv6))
+			return tmp;
+
+	/* item may have moved during lookup - check nulls and restart
+	 * if that's the case
+	 */
+	if (get_nulls_value(ntmp) != slot)
+		goto begin;
+
+	return NULL;
+}
+
+/**
+ * ovpn_peer_transp_match - check if sockaddr and peer binding match
+ * @peer: the peer to get the binding from
+ * @ss: the sockaddr to match
+ *
+ * Return: true if sockaddr and binding match or false otherwise
+ */
+static bool ovpn_peer_transp_match(const struct ovpn_peer *peer,
+				   const struct sockaddr_storage *ss)
+{
+	struct ovpn_bind *bind = rcu_dereference(peer->bind);
+	struct sockaddr_in6 *sa6;
+	struct sockaddr_in *sa4;
+
+	if (unlikely(!bind))
+		return false;
+
+	if (ss->ss_family != bind->remote.in4.sin_family)
+		return false;
+
+	switch (ss->ss_family) {
+	case AF_INET:
+		sa4 = (struct sockaddr_in *)ss;
+		if (sa4->sin_addr.s_addr != bind->remote.in4.sin_addr.s_addr)
+			return false;
+		if (sa4->sin_port != bind->remote.in4.sin_port)
+			return false;
+		break;
+	case AF_INET6:
+		sa6 = (struct sockaddr_in6 *)ss;
+		if (!ipv6_addr_equal(&sa6->sin6_addr,
+				     &bind->remote.in6.sin6_addr))
+			return false;
+		if (sa6->sin6_port != bind->remote.in6.sin6_port)
+			return false;
+		break;
+	default:
+		return false;
+	}
+
+	return true;
+}
+
+/**
+ * ovpn_peer_get_by_transp_addr_p2p - get peer by transport address in a P2P
+ *                                    instance
+ * @ovpn: the openvpn instance to search
+ * @ss: the transport socket address
+ *
+ * Return: the peer if found or NULL otherwise
+ */
+static struct ovpn_peer *
+ovpn_peer_get_by_transp_addr_p2p(struct ovpn_priv *ovpn,
+				 struct sockaddr_storage *ss)
+{
+	struct ovpn_peer *tmp, *peer = NULL;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(ovpn->peer);
+	if (likely(tmp && ovpn_peer_transp_match(tmp, ss) &&
+		   ovpn_peer_hold(tmp)))
+		peer = tmp;
+	rcu_read_unlock();
+
+	return peer;
+}
+
+/**
+ * ovpn_peer_get_by_transp_addr - retrieve peer by transport address
+ * @ovpn: the openvpn instance to search
+ * @skb: the skb to retrieve the source transport address from
+ *
+ * Return: a pointer to the peer if found or NULL otherwise
+ */
+struct ovpn_peer *ovpn_peer_get_by_transp_addr(struct ovpn_priv *ovpn,
+					       struct sk_buff *skb)
+{
+	struct ovpn_peer *tmp, *peer = NULL;
+	struct sockaddr_storage ss = { 0 };
+	struct hlist_nulls_head *nhead;
+	struct hlist_nulls_node *ntmp;
+	unsigned int slot;
+	ssize_t sa_len;
+
+	sa_len = ovpn_peer_skb_to_sockaddr(skb, &ss);
+	if (unlikely(sa_len < 0))
+		return NULL;
+
+	if (ovpn->mode == OVPN_MODE_P2P)
+		return ovpn_peer_get_by_transp_addr_p2p(ovpn, &ss);
+
+	rcu_read_lock();
+begin:
+	slot = ovpn_get_hash_slot(ovpn->peers->by_transp_addr, &ss, sa_len);
+	nhead = &ovpn->peers->by_transp_addr[slot];
+
+	hlist_nulls_for_each_entry_rcu(tmp, ntmp, nhead,
+				       hash_entry_transp_addr) {
+		if (!ovpn_peer_transp_match(tmp, &ss))
+			continue;
+
+		if (!ovpn_peer_hold(tmp))
+			continue;
+
+		peer = tmp;
+		break;
+	}
+
+	/* item may have moved during lookup - check nulls and restart
+	 * if that's the case
+	 */
+	if (!peer && get_nulls_value(ntmp) != slot)
+		goto begin;
+	rcu_read_unlock();
+
+	return peer;
+}
+
+/**
+ * ovpn_peer_get_by_id_p2p - get peer by ID in a P2P instance
+ * @ovpn: the openvpn instance to search
+ * @peer_id: the ID of the peer to find
+ *
+ * Return: the peer if found or NULL otherwise
+ */
+static struct ovpn_peer *ovpn_peer_get_by_id_p2p(struct ovpn_priv *ovpn,
+						 u32 peer_id)
+{
+	struct ovpn_peer *tmp, *peer = NULL;
+
+	rcu_read_lock();
+	tmp = rcu_dereference(ovpn->peer);
+	if (likely(tmp && tmp->id == peer_id && ovpn_peer_hold(tmp)))
+		peer = tmp;
+	rcu_read_unlock();
+
+	return peer;
+}
+
+/**
+ * ovpn_peer_get_by_id - retrieve peer by ID
+ * @ovpn: the openvpn instance to search
+ * @peer_id: the unique peer identifier to match
+ *
+ * Return: a pointer to the peer if found or NULL otherwise
+ */
+struct ovpn_peer *ovpn_peer_get_by_id(struct ovpn_priv *ovpn, u32 peer_id)
+{
+	struct ovpn_peer *tmp, *peer = NULL;
+	struct hlist_head *head;
+
+	if (ovpn->mode == OVPN_MODE_P2P)
+		return ovpn_peer_get_by_id_p2p(ovpn, peer_id);
+
+	head = ovpn_get_hash_head(ovpn->peers->by_id, &peer_id,
+				  sizeof(peer_id));
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(tmp, head, hash_entry_id) {
+		if (tmp->id != peer_id)
+			continue;
+
+		if (!ovpn_peer_hold(tmp))
+			continue;
+
+		peer = tmp;
+		break;
+	}
+	rcu_read_unlock();
+
+	return peer;
+}
+
+static void ovpn_peer_remove(struct ovpn_peer *peer,
+			     enum ovpn_del_peer_reason reason,
+			     struct llist_head *release_list)
+{
+	lockdep_assert_held(&peer->ovpn->lock);
+
+	switch (peer->ovpn->mode) {
+	case OVPN_MODE_MP:
+		/* prevent double remove */
+		if (hlist_unhashed(&peer->hash_entry_id))
+			return;
+
+		hlist_del_init_rcu(&peer->hash_entry_id);
+		hlist_nulls_del_init_rcu(&peer->hash_entry_addr4);
+		hlist_nulls_del_init_rcu(&peer->hash_entry_addr6);
+		hlist_nulls_del_init_rcu(&peer->hash_entry_transp_addr);
+		break;
+	case OVPN_MODE_P2P:
+		/* prevent double remove */
+		if (peer != rcu_access_pointer(peer->ovpn->peer))
+			return;
+
+		RCU_INIT_POINTER(peer->ovpn->peer, NULL);
+		/* in P2P mode the carrier is switched off when the peer is
+		 * deleted so that third party protocols can react accordingly
+		 */
+		netif_carrier_off(peer->ovpn->dev);
+		break;
+	}
+
+	peer->delete_reason = reason;
+	ovpn_nl_peer_del_notify(peer);
+
+	/* append to provided list for later socket release and ref drop */
+	llist_add(&peer->release_entry, release_list);
+}
+
+/**
+ * ovpn_peer_get_by_dst - Lookup peer to send skb to
+ * @ovpn: the private data representing the current VPN session
+ * @skb: the skb to extract the destination address from
+ *
+ * This function takes a tunnel packet and looks up the peer to send it to
+ * after encapsulation. The skb is expected to be the in-tunnel packet, without
+ * any OpenVPN related header.
+ *
+ * Assume that the IP header is accessible in the skb data.
+ *
+ * Return: the peer if found or NULL otherwise.
+ */
+struct ovpn_peer *ovpn_peer_get_by_dst(struct ovpn_priv *ovpn,
+				       struct sk_buff *skb)
+{
+	struct ovpn_peer *peer = NULL;
+	struct in6_addr addr6;
+	__be32 addr4;
+
+	/* in P2P mode, no matter the destination, packets are always sent to
+	 * the single peer listening on the other side
+	 */
+	if (ovpn->mode == OVPN_MODE_P2P) {
+		rcu_read_lock();
+		peer = rcu_dereference(ovpn->peer);
+		if (unlikely(peer && !ovpn_peer_hold(peer)))
+			peer = NULL;
+		rcu_read_unlock();
+		return peer;
+	}
+
+	rcu_read_lock();
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		addr4 = ovpn_nexthop_from_skb4(skb);
+		peer = ovpn_peer_get_by_vpn_addr4(ovpn, addr4);
+		break;
+	case htons(ETH_P_IPV6):
+		addr6 = ovpn_nexthop_from_skb6(skb);
+		peer = ovpn_peer_get_by_vpn_addr6(ovpn, &addr6);
+		break;
+	}
+
+	if (unlikely(peer && !ovpn_peer_hold(peer)))
+		peer = NULL;
+	rcu_read_unlock();
+
+	return peer;
+}
+
+/**
+ * ovpn_nexthop_from_rt4 - look up the IPv4 nexthop for the given destination
+ * @ovpn: the private data representing the current VPN session
+ * @dest: the destination to be looked up
+ *
+ * Looks up in the IPv4 system routing table the IP of the nexthop to be used
+ * to reach the destination passed as argument. If no nexthop can be found, the
+ * destination itself is returned as it probably has to be used as nexthop.
+ *
+ * Return: the IP of the next hop if found or dest itself otherwise
+ */
+static __be32 ovpn_nexthop_from_rt4(struct ovpn_priv *ovpn, __be32 dest)
+{
+	struct rtable *rt;
+	struct flowi4 fl = {
+		.daddr = dest
+	};
+
+	rt = ip_route_output_flow(dev_net(ovpn->dev), &fl, NULL);
+	if (IS_ERR(rt)) {
+		net_dbg_ratelimited("%s: no route to host %pI4\n",
+				    netdev_name(ovpn->dev), &dest);
+		/* if we end up here this packet is probably going to be
+		 * thrown away later
+		 */
+		return dest;
+	}
+
+	if (!rt->rt_uses_gateway)
+		goto out;
+
+	dest = rt->rt_gw4;
+out:
+	ip_rt_put(rt);
+	return dest;
+}
+
+/**
+ * ovpn_nexthop_from_rt6 - look up the IPv6 nexthop for the given destination
+ * @ovpn: the private data representing the current VPN session
+ * @dest: the destination to be looked up
+ *
+ * Looks up in the IPv6 system routing table the IP of the nexthop to be used
+ * to reach the destination passed as argument. If no nexthop can be found, the
+ * destination itself is returned as it probably has to be used as nexthop.
+ *
+ * Return: the IP of the next hop if found or dest itself otherwise
+ */
+static struct in6_addr ovpn_nexthop_from_rt6(struct ovpn_priv *ovpn,
+					     struct in6_addr dest)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	struct dst_entry *entry;
+	struct rt6_info *rt;
+	struct flowi6 fl = {
+		.daddr = dest,
+	};
+
+	entry = ipv6_stub->ipv6_dst_lookup_flow(dev_net(ovpn->dev), NULL, &fl,
+						NULL);
+	if (IS_ERR(entry)) {
+		net_dbg_ratelimited("%s: no route to host %pI6c\n",
+				    netdev_name(ovpn->dev), &dest);
+		/* if we end up here this packet is probably going to be
+		 * thrown away later
+		 */
+		return dest;
+	}
+
+	rt = dst_rt6_info(entry);
+
+	if (!(rt->rt6i_flags & RTF_GATEWAY))
+		goto out;
+
+	dest = rt->rt6i_gateway;
+out:
+	dst_release((struct dst_entry *)rt);
+#endif
+	return dest;
+}
+
+/**
+ * ovpn_peer_check_by_src - check that skb source is routed via peer
+ * @ovpn: the openvpn instance to search
+ * @skb: the packet to extract source address from
+ * @peer: the peer to check against the source address
+ *
+ * Return: true if the peer is matching or false otherwise
+ */
+bool ovpn_peer_check_by_src(struct ovpn_priv *ovpn, struct sk_buff *skb,
+			    struct ovpn_peer *peer)
+{
+	bool match = false;
+	struct in6_addr addr6;
+	__be32 addr4;
+
+	if (ovpn->mode == OVPN_MODE_P2P) {
+		/* in P2P mode, no matter the destination, packets are always
+		 * sent to the single peer listening on the other side
+		 */
+		return peer == rcu_access_pointer(ovpn->peer);
+	}
+
+	/* This function performs a reverse path check, therefore we now
+	 * lookup the nexthop we would use if we wanted to route a packet
+	 * to the source IP. If the nexthop matches the sender we know the
+	 * latter is valid and we allow the packet to come in
+	 */
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		addr4 = ovpn_nexthop_from_rt4(ovpn, ip_hdr(skb)->saddr);
+		rcu_read_lock();
+		match = (peer == ovpn_peer_get_by_vpn_addr4(ovpn, addr4));
+		rcu_read_unlock();
+		break;
+	case htons(ETH_P_IPV6):
+		addr6 = ovpn_nexthop_from_rt6(ovpn, ipv6_hdr(skb)->saddr);
+		rcu_read_lock();
+		match = (peer == ovpn_peer_get_by_vpn_addr6(ovpn, &addr6));
+		rcu_read_unlock();
+		break;
+	}
+
+	return match;
+}
+
+void ovpn_peer_hash_vpn_ip(struct ovpn_peer *peer)
+{
+	struct hlist_nulls_head *nhead;
+
+	lockdep_assert_held(&peer->ovpn->lock);
+
+	/* rehashing makes sense only in multipeer mode */
+	if (peer->ovpn->mode != OVPN_MODE_MP)
+		return;
+
+	if (peer->vpn_addrs.ipv4.s_addr != htonl(INADDR_ANY)) {
+		/* remove potential old hashing */
+		hlist_nulls_del_init_rcu(&peer->hash_entry_addr4);
+
+		nhead = ovpn_get_hash_head(peer->ovpn->peers->by_vpn_addr4,
+					   &peer->vpn_addrs.ipv4,
+					   sizeof(peer->vpn_addrs.ipv4));
+		hlist_nulls_add_head_rcu(&peer->hash_entry_addr4, nhead);
+	}
+
+	if (!ipv6_addr_any(&peer->vpn_addrs.ipv6)) {
+		/* remove potential old hashing */
+		hlist_nulls_del_init_rcu(&peer->hash_entry_addr6);
+
+		nhead = ovpn_get_hash_head(peer->ovpn->peers->by_vpn_addr6,
+					   &peer->vpn_addrs.ipv6,
+					   sizeof(peer->vpn_addrs.ipv6));
+		hlist_nulls_add_head_rcu(&peer->hash_entry_addr6, nhead);
+	}
+}
+
+/**
+ * ovpn_peer_add_mp - add peer 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_priv *ovpn, struct ovpn_peer *peer)
+{
+	struct sockaddr_storage sa = { 0 };
+	struct hlist_nulls_head *nhead;
+	struct sockaddr_in6 *sa6;
+	struct sockaddr_in *sa4;
+	struct ovpn_bind *bind;
+	struct ovpn_peer *tmp;
+	size_t salen;
+	int ret = 0;
+
+	spin_lock_bh(&ovpn->lock);
+	/* do not add duplicates */
+	tmp = ovpn_peer_get_by_id(ovpn, peer->id);
+	if (tmp) {
+		ovpn_peer_put(tmp);
+		ret = -EEXIST;
+		goto out;
+	}
+
+	bind = rcu_dereference_protected(peer->bind, true);
+	/* peers connected via TCP have bind == NULL */
+	if (bind) {
+		switch (bind->remote.in4.sin_family) {
+		case AF_INET:
+			sa4 = (struct sockaddr_in *)&sa;
+
+			sa4->sin_family = AF_INET;
+			sa4->sin_addr.s_addr = bind->remote.in4.sin_addr.s_addr;
+			sa4->sin_port = bind->remote.in4.sin_port;
+			salen = sizeof(*sa4);
+			break;
+		case AF_INET6:
+			sa6 = (struct sockaddr_in6 *)&sa;
+
+			sa6->sin6_family = AF_INET6;
+			sa6->sin6_addr = bind->remote.in6.sin6_addr;
+			sa6->sin6_port = bind->remote.in6.sin6_port;
+			salen = sizeof(*sa6);
+			break;
+		default:
+			ret = -EPROTONOSUPPORT;
+			goto out;
+		}
+
+		nhead = ovpn_get_hash_head(ovpn->peers->by_transp_addr, &sa,
+					   salen);
+		hlist_nulls_add_head_rcu(&peer->hash_entry_transp_addr, nhead);
+	}
+
+	hlist_add_head_rcu(&peer->hash_entry_id,
+			   ovpn_get_hash_head(ovpn->peers->by_id, &peer->id,
+					      sizeof(peer->id)));
+
+	ovpn_peer_hash_vpn_ip(peer);
+out:
+	spin_unlock_bh(&ovpn->lock);
+	return ret;
+}
+
+/**
+ * ovpn_peer_add_p2p - add peer to related tables in a P2P 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_p2p(struct ovpn_priv *ovpn, struct ovpn_peer *peer)
+{
+	LLIST_HEAD(release_list);
+	struct ovpn_peer *tmp;
+
+	spin_lock_bh(&ovpn->lock);
+	/* in p2p mode it is possible to have a single peer only, therefore the
+	 * old one is released and substituted by the new one
+	 */
+	tmp = rcu_dereference_protected(ovpn->peer,
+					lockdep_is_held(&ovpn->lock));
+	if (tmp)
+		ovpn_peer_remove(tmp, OVPN_DEL_PEER_REASON_TEARDOWN,
+				 &release_list);
+
+	rcu_assign_pointer(ovpn->peer, peer);
+	/* in P2P mode the carrier is switched on when the peer is added */
+	netif_carrier_on(ovpn->dev);
+	unlock_ovpn(ovpn, &release_list);
+
+	return 0;
+}
+
+/**
+ * ovpn_peer_add - add peer to the related tables
+ * @ovpn: the openvpn instance the peer belongs to
+ * @peer: the peer object to add
+ *
+ * Assume refcounter was increased by caller
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+int ovpn_peer_add(struct ovpn_priv *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);
+	}
+
+	return -EOPNOTSUPP;
+}
+
+/**
+ * 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)
+ * @release_list: list where delete peer should be appended
+ *
+ * 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 llist_head *release_list)
+{
+	struct ovpn_peer *tmp;
+	int ret = -ENOENT;
+
+	lockdep_assert_held(&peer->ovpn->lock);
+
+	tmp = ovpn_peer_get_by_id(peer->ovpn, peer->id);
+	if (tmp == peer) {
+		ovpn_peer_remove(peer, reason, release_list);
+		ret = 0;
+	}
+
+	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
+ * @reason: reason why the peer was deleted (sent to userspace)
+ * @release_list: list where delete peer should be appended
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+static int ovpn_peer_del_p2p(struct ovpn_peer *peer,
+			     enum ovpn_del_peer_reason reason,
+			     struct llist_head *release_list)
+{
+	struct ovpn_peer *tmp;
+
+	lockdep_assert_held(&peer->ovpn->lock);
+
+	tmp = rcu_dereference_protected(peer->ovpn->peer,
+					lockdep_is_held(&peer->ovpn->lock));
+	if (tmp != peer)
+		return -ENOENT;
+
+	ovpn_peer_remove(peer, reason, release_list);
+
+	return 0;
+}
+
+/**
+ * ovpn_peer_del - delete peer from related tables
+ * @peer: the peer object to delete
+ * @reason: reason for deleting peer (will be sent to userspace)
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+int ovpn_peer_del(struct ovpn_peer *peer, enum ovpn_del_peer_reason reason)
+{
+	LLIST_HEAD(release_list);
+	int ret = -EOPNOTSUPP;
+
+	spin_lock_bh(&peer->ovpn->lock);
+	switch (peer->ovpn->mode) {
+	case OVPN_MODE_MP:
+		ret = ovpn_peer_del_mp(peer, reason, &release_list);
+		break;
+	case OVPN_MODE_P2P:
+		ret = ovpn_peer_del_p2p(peer, reason, &release_list);
+		break;
+	default:
+		break;
+	}
+	unlock_ovpn(peer->ovpn, &release_list);
+
+	return ret;
+}
+
+/**
+ * ovpn_peer_release_p2p - release peer upon P2P device teardown
+ * @ovpn: the instance being torn down
+ * @sk: if not NULL, release peer only if it's using this specific socket
+ * @reason: the reason for releasing the peer
+ */
+static void ovpn_peer_release_p2p(struct ovpn_priv *ovpn, struct sock *sk,
+				  enum ovpn_del_peer_reason reason)
+{
+	struct ovpn_socket *ovpn_sock;
+	LLIST_HEAD(release_list);
+	struct ovpn_peer *peer;
+
+	spin_lock_bh(&ovpn->lock);
+	peer = rcu_dereference_protected(ovpn->peer,
+					 lockdep_is_held(&ovpn->lock));
+	if (!peer) {
+		spin_unlock_bh(&ovpn->lock);
+		return;
+	}
+
+	if (sk) {
+		ovpn_sock = rcu_access_pointer(peer->sock);
+		if (!ovpn_sock || ovpn_sock->sock->sk != sk) {
+			spin_unlock_bh(&ovpn->lock);
+			ovpn_peer_put(peer);
+			return;
+		}
+	}
+
+	ovpn_peer_remove(peer, reason, &release_list);
+	unlock_ovpn(ovpn, &release_list);
+}
+
+static void ovpn_peers_release_mp(struct ovpn_priv *ovpn, struct sock *sk,
+				  enum ovpn_del_peer_reason reason)
+{
+	struct ovpn_socket *ovpn_sock;
+	LLIST_HEAD(release_list);
+	struct ovpn_peer *peer;
+	struct hlist_node *tmp;
+	int bkt;
+
+	spin_lock_bh(&ovpn->lock);
+	hash_for_each_safe(ovpn->peers->by_id, bkt, tmp, peer, hash_entry_id) {
+		bool remove = true;
+
+		/* if a socket was passed as argument, skip all peers except
+		 * those using it
+		 */
+		if (sk) {
+			rcu_read_lock();
+			ovpn_sock = rcu_dereference(peer->sock);
+			remove = ovpn_sock && ovpn_sock->sock->sk == sk;
+			rcu_read_unlock();
+		}
+
+		if (remove)
+			ovpn_peer_remove(peer, reason, &release_list);
+	}
+	unlock_ovpn(ovpn, &release_list);
+}
+
+/**
+ * ovpn_peers_free - free all peers in the instance
+ * @ovpn: the instance whose peers should be released
+ * @sk: if not NULL, only peers using this socket are removed and the socket
+ *      is released immediately
+ * @reason: the reason for releasing all peers
+ */
+void ovpn_peers_free(struct ovpn_priv *ovpn, struct sock *sk,
+		     enum ovpn_del_peer_reason reason)
+{
+	switch (ovpn->mode) {
+	case OVPN_MODE_P2P:
+		ovpn_peer_release_p2p(ovpn, sk, reason);
+		break;
+	case OVPN_MODE_MP:
+		ovpn_peers_release_mp(ovpn, sk, reason);
+		break;
+	}
+}
+
+static time64_t ovpn_peer_keepalive_work_single(struct ovpn_peer *peer,
+						time64_t now,
+						struct llist_head *release_list)
+{
+	time64_t last_recv, last_sent, next_run1, next_run2;
+	unsigned long timeout, interval;
+	bool expired;
+
+	spin_lock_bh(&peer->lock);
+	/* we expect both timers to be configured at the same time,
+	 * therefore bail out if either is not set
+	 */
+	if (!peer->keepalive_timeout || !peer->keepalive_interval) {
+		spin_unlock_bh(&peer->lock);
+		return 0;
+	}
+
+	/* check for peer timeout */
+	expired = false;
+	timeout = peer->keepalive_timeout;
+	last_recv = READ_ONCE(peer->last_recv);
+	if (now < last_recv + timeout) {
+		peer->keepalive_recv_exp = last_recv + timeout;
+		next_run1 = peer->keepalive_recv_exp;
+	} else if (peer->keepalive_recv_exp > now) {
+		next_run1 = peer->keepalive_recv_exp;
+	} else {
+		expired = true;
+	}
+
+	if (expired) {
+		/* peer is dead -> kill it and move on */
+		spin_unlock_bh(&peer->lock);
+		netdev_dbg(peer->ovpn->dev, "peer %u expired\n",
+			   peer->id);
+		ovpn_peer_remove(peer, OVPN_DEL_PEER_REASON_EXPIRED,
+				 release_list);
+		return 0;
+	}
+
+	/* check for peer keepalive */
+	expired = false;
+	interval = peer->keepalive_interval;
+	last_sent = READ_ONCE(peer->last_sent);
+	if (now < last_sent + interval) {
+		peer->keepalive_xmit_exp = last_sent + interval;
+		next_run2 = peer->keepalive_xmit_exp;
+	} else if (peer->keepalive_xmit_exp > now) {
+		next_run2 = peer->keepalive_xmit_exp;
+	} else {
+		expired = true;
+		next_run2 = now + interval;
+	}
+	spin_unlock_bh(&peer->lock);
+
+	if (expired) {
+		/* a keepalive packet is required */
+		netdev_dbg(peer->ovpn->dev,
+			   "sending keepalive to peer %u\n",
+			   peer->id);
+		if (schedule_work(&peer->keepalive_work))
+			ovpn_peer_hold(peer);
+	}
+
+	if (next_run1 < next_run2)
+		return next_run1;
+
+	return next_run2;
+}
+
+static time64_t ovpn_peer_keepalive_work_mp(struct ovpn_priv *ovpn,
+					    time64_t now,
+					    struct llist_head *release_list)
+{
+	time64_t tmp_next_run, next_run = 0;
+	struct hlist_node *tmp;
+	struct ovpn_peer *peer;
+	int bkt;
+
+	lockdep_assert_held(&ovpn->lock);
+
+	hash_for_each_safe(ovpn->peers->by_id, bkt, tmp, peer, hash_entry_id) {
+		tmp_next_run = ovpn_peer_keepalive_work_single(peer, now,
+							       release_list);
+		if (!tmp_next_run)
+			continue;
+
+		/* the next worker run will be scheduled based on the shortest
+		 * required interval across all peers
+		 */
+		if (!next_run || tmp_next_run < next_run)
+			next_run = tmp_next_run;
+	}
+
+	return next_run;
+}
+
+static time64_t ovpn_peer_keepalive_work_p2p(struct ovpn_priv *ovpn,
+					     time64_t now,
+					     struct llist_head *release_list)
+{
+	struct ovpn_peer *peer;
+	time64_t next_run = 0;
+
+	lockdep_assert_held(&ovpn->lock);
+
+	peer = rcu_dereference_protected(ovpn->peer,
+					 lockdep_is_held(&ovpn->lock));
+	if (peer)
+		next_run = ovpn_peer_keepalive_work_single(peer, now,
+							   release_list);
+
+	return next_run;
+}
+
+/**
+ * ovpn_peer_keepalive_work - run keepalive logic on each known peer
+ * @work: pointer to the work member of the related ovpn object
+ *
+ * Each peer has two timers (if configured):
+ * 1. peer timeout: when no data is received for a certain interval,
+ *    the peer is considered dead and it gets killed.
+ * 2. peer keepalive: when no data is sent to a certain peer for a
+ *    certain interval, a special 'keepalive' packet is explicitly sent.
+ *
+ * This function iterates across the whole peer collection while
+ * checking the timers described above.
+ */
+void ovpn_peer_keepalive_work(struct work_struct *work)
+{
+	struct ovpn_priv *ovpn = container_of(work, struct ovpn_priv,
+					      keepalive_work.work);
+	time64_t next_run = 0, now = ktime_get_real_seconds();
+	LLIST_HEAD(release_list);
+
+	spin_lock_bh(&ovpn->lock);
+	switch (ovpn->mode) {
+	case OVPN_MODE_MP:
+		next_run = ovpn_peer_keepalive_work_mp(ovpn, now,
+						       &release_list);
+		break;
+	case OVPN_MODE_P2P:
+		next_run = ovpn_peer_keepalive_work_p2p(ovpn, now,
+							&release_list);
+		break;
+	}
+
+	/* prevent rearming if the interface is being destroyed */
+	if (next_run > 0) {
+		netdev_dbg(ovpn->dev,
+			   "scheduling keepalive work: now=%llu next_run=%llu delta=%llu\n",
+			   next_run, now, next_run - now);
+		schedule_delayed_work(&ovpn->keepalive_work,
+				      (next_run - now) * HZ);
+	}
+	unlock_ovpn(ovpn, &release_list);
+}