@@ -9,14 +9,78 @@
#include <linux/netdevice.h>
#include <linux/skbuff.h>
+#include <net/gro_cells.h>
#include <net/gso.h>
-#include "io.h"
#include "ovpnstruct.h"
#include "peer.h"
+#include "io.h"
+#include "netlink.h"
+#include "proto.h"
#include "udp.h"
#include "skb.h"
+/* Called after decrypt to write the IP packet to the device.
+ * This method is expected to manage/free the skb.
+ */
+static void ovpn_netdev_write(struct ovpn_peer *peer, struct sk_buff *skb)
+{
+ /* packet integrity was verified on the VPN layer - no need to perform
+ * any additional check along the stack
+ */
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ skb->csum_level = ~0;
+
+ /* skb hash for transport packet no longer valid after decapsulation */
+ skb_clear_hash(skb);
+
+ /* post-decrypt scrub -- prepare to inject encapsulated packet onto the
+ * interface, based on __skb_tunnel_rx() in dst.h
+ */
+ skb->dev = peer->ovpn->dev;
+ skb_set_queue_mapping(skb, 0);
+ skb_scrub_packet(skb, true);
+
+ skb_reset_network_header(skb);
+ skb_reset_transport_header(skb);
+ skb_probe_transport_header(skb);
+ skb_reset_inner_headers(skb);
+
+ memset(skb->cb, 0, sizeof(skb->cb));
+
+ /* cause packet to be "received" by the interface */
+ if (likely(gro_cells_receive(&peer->ovpn->gro_cells,
+ skb) == NET_RX_SUCCESS))
+ /* update RX stats with the size of decrypted packet */
+ dev_sw_netstats_rx_add(peer->ovpn->dev, skb->len);
+ else
+ dev_core_stats_rx_dropped_inc(peer->ovpn->dev);
+}
+
+static void ovpn_decrypt_post(struct sk_buff *skb, int ret)
+{
+ struct ovpn_peer *peer = ovpn_skb_cb(skb)->peer;
+
+ if (unlikely(ret < 0))
+ goto drop;
+
+ ovpn_netdev_write(peer, skb);
+ /* skb is passed to upper layer - don't free it */
+ skb = NULL;
+drop:
+ if (unlikely(skb))
+ dev_core_stats_rx_dropped_inc(peer->ovpn->dev);
+ kfree_skb(skb);
+ ovpn_peer_put(peer);
+}
+
+/* pick next packet from RX queue, decrypt and forward it to the device */
+void ovpn_recv(struct ovpn_peer *peer, struct sk_buff *skb)
+{
+ ovpn_skb_cb(skb)->peer = peer;
+ ovpn_decrypt_post(skb, 0);
+}
+
static void ovpn_encrypt_post(struct sk_buff *skb, int ret)
{
struct ovpn_peer *peer = ovpn_skb_cb(skb)->peer;
@@ -12,6 +12,6 @@
netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev);
-void ovpn_encrypt_work(struct work_struct *work);
+void ovpn_recv(struct ovpn_peer *peer, struct sk_buff *skb);
#endif /* _NET_OVPN_OVPN_H_ */
@@ -13,6 +13,7 @@
#include <linux/inetdevice.h>
//#include <linux/rcupdate.h>
#include <linux/version.h>
+#include <net/gro_cells.h>
#include <net/ip.h>
#include <net/rtnetlink.h>
#include <uapi/linux/if_arp.h>
@@ -49,11 +50,17 @@ static int ovpn_struct_init(struct net_device *dev, enum ovpn_mode mode)
static void ovpn_struct_free(struct net_device *net)
{
+ struct ovpn_struct *ovpn = netdev_priv(net);
+
+ gro_cells_destroy(&ovpn->gro_cells);
+ rcu_barrier();
}
static int ovpn_net_init(struct net_device *dev)
{
- return 0;
+ struct ovpn_struct *ovpn = netdev_priv(dev);
+
+ return gro_cells_init(&ovpn->gro_cells, dev);
}
static int ovpn_net_open(struct net_device *dev)
@@ -10,6 +10,7 @@
#ifndef _NET_OVPN_OVPNSTRUCT_H_
#define _NET_OVPN_OVPNSTRUCT_H_
+#include <net/gro_cells.h>
#include <uapi/linux/ovpn.h>
/**
@@ -20,6 +21,7 @@
* @lock: protect this object
* @peer: in P2P mode, this is the only remote peer
* @dev_list: entry for the module wide device list
+ * @gro_cells: pointer to the Generic Receive Offload cell
*/
struct ovpn_struct {
struct net_device *dev;
@@ -28,6 +30,7 @@ struct ovpn_struct {
spinlock_t lock; /* protect writing to the ovpn_struct object */
struct ovpn_peer __rcu *peer;
struct list_head dev_list;
+ struct gro_cells gro_cells;
};
#endif /* _NET_OVPN_OVPNSTRUCT_H_ */
new file mode 100644
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 OpenVPN, Inc.
+ *
+ * Author: Antonio Quartulli <antonio@openvpn.net>
+ * James Yonan <james@openvpn.net>
+ */
+
+#ifndef _NET_OVPN_OVPNPROTO_H_
+#define _NET_OVPN_OVPNPROTO_H_
+
+#include "main.h"
+
+#include <linux/skbuff.h>
+
+/* Methods for operating on the initial command
+ * byte of the OpenVPN protocol.
+ */
+
+/* packet opcode (high 5 bits) and key-id (low 3 bits) are combined in
+ * one byte
+ */
+#define OVPN_KEY_ID_MASK 0x07
+#define OVPN_OPCODE_SHIFT 3
+#define OVPN_OPCODE_MASK 0x1F
+/* upper bounds on opcode and key ID */
+#define OVPN_KEY_ID_MAX (OVPN_KEY_ID_MASK + 1)
+#define OVPN_OPCODE_MAX (OVPN_OPCODE_MASK + 1)
+/* packet opcodes of interest to us */
+#define OVPN_DATA_V1 6 /* data channel V1 packet */
+#define OVPN_DATA_V2 9 /* data channel V2 packet */
+/* size of initial packet opcode */
+#define OVPN_OP_SIZE_V1 1
+#define OVPN_OP_SIZE_V2 4
+#define OVPN_PEER_ID_MASK 0x00FFFFFF
+#define OVPN_PEER_ID_UNDEF 0x00FFFFFF
+/* first byte of keepalive message */
+#define OVPN_KEEPALIVE_FIRST_BYTE 0x2a
+/* first byte of exit message */
+#define OVPN_EXPLICIT_EXIT_NOTIFY_FIRST_BYTE 0x28
+
+/**
+ * ovpn_opcode_from_skb - extract OP code from skb at specified offset
+ * @skb: the packet to extract the OP code from
+ * @offset: the offset in the data buffer where the OP code is located
+ *
+ * Note: this function assumes that the skb head was pulled enough
+ * to access the first byte.
+ *
+ * Return: the OP code
+ */
+static inline u8 ovpn_opcode_from_skb(const struct sk_buff *skb, u16 offset)
+{
+ u8 byte = *(skb->data + offset);
+
+ return byte >> OVPN_OPCODE_SHIFT;
+}
+
+/**
+ * ovpn_peer_id_from_skb - extract peer ID from skb at specified offset
+ * @skb: the packet to extract the OP code from
+ * @offset: the offset in the data buffer where the OP code is located
+ *
+ * Note: this function assumes that the skb head was pulled enough
+ * to access the first 4 bytes.
+ *
+ * Return: the peer ID.
+ */
+static inline u32 ovpn_peer_id_from_skb(const struct sk_buff *skb, u16 offset)
+{
+ return ntohl(*(__be32 *)(skb->data + offset)) & OVPN_PEER_ID_MASK;
+}
+
+#endif /* _NET_OVPN_OVPNPROTO_H_ */
@@ -18,10 +18,7 @@
#include <linux/types.h>
struct ovpn_cb {
- struct aead_request *req;
struct ovpn_peer *peer;
- struct ovpn_crypto_key_slot *ks;
- unsigned int payload_offset;
};
static inline struct ovpn_cb *ovpn_skb_cb(struct sk_buff *skb)
@@ -22,6 +22,9 @@ static void ovpn_socket_detach(struct socket *sock)
if (!sock)
return;
+ if (sock->sk->sk_protocol == IPPROTO_UDP)
+ ovpn_udp_socket_detach(sock);
+
sockfd_put(sock);
}
@@ -71,6 +74,27 @@ static int ovpn_socket_attach(struct socket *sock, struct ovpn_peer *peer)
return ret;
}
+/* Retrieve the corresponding ovpn object from a UDP socket
+ * rcu_read_lock must be held on entry
+ */
+struct ovpn_struct *ovpn_from_udp_sock(struct sock *sk)
+{
+ struct ovpn_socket *ovpn_sock;
+
+ if (unlikely(READ_ONCE(udp_sk(sk)->encap_type) != UDP_ENCAP_OVPNINUDP))
+ return NULL;
+
+ ovpn_sock = rcu_dereference_sk_user_data(sk);
+ if (unlikely(!ovpn_sock))
+ return NULL;
+
+ /* make sure that sk matches our stored transport socket */
+ if (unlikely(!ovpn_sock->sock || sk != ovpn_sock->sock->sk))
+ return NULL;
+
+ return ovpn_sock->ovpn;
+}
+
/**
* ovpn_socket_new - create a new socket and initialize it
* @sock: the kernel socket to embed
@@ -21,9 +21,94 @@
#include "bind.h"
#include "io.h"
#include "peer.h"
+#include "proto.h"
#include "socket.h"
#include "udp.h"
+/**
+ * ovpn_udp_encap_recv - Start processing a received UDP packet.
+ * @sk: socket over which the packet was received
+ * @skb: the received packet
+ *
+ * If the first byte of the payload is DATA_V2, the packet is further processed,
+ * otherwise it is forwarded to the UDP stack for delivery to user space.
+ *
+ * Return:
+ * 0 if skb was consumed or dropped
+ * >0 if skb should be passed up to userspace as UDP (packet not consumed)
+ * <0 if skb should be resubmitted as proto -N (packet not consumed)
+ */
+static int ovpn_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
+{
+ struct ovpn_peer *peer = NULL;
+ struct ovpn_struct *ovpn;
+ u32 peer_id;
+ u8 opcode;
+
+ ovpn = ovpn_from_udp_sock(sk);
+ if (unlikely(!ovpn)) {
+ net_err_ratelimited("%s: cannot obtain ovpn object from UDP socket\n",
+ __func__);
+ goto drop;
+ }
+
+ /* Make sure the first 4 bytes of the skb data buffer after the UDP
+ * header are accessible.
+ * They are required to fetch the OP code, the key ID and the peer ID.
+ */
+ if (unlikely(!pskb_may_pull(skb, sizeof(struct udphdr) +
+ OVPN_OP_SIZE_V2))) {
+ net_dbg_ratelimited("%s: packet too small\n", __func__);
+ goto drop;
+ }
+
+ opcode = ovpn_opcode_from_skb(skb, sizeof(struct udphdr));
+ if (unlikely(opcode != OVPN_DATA_V2)) {
+ /* DATA_V1 is not supported */
+ if (opcode == OVPN_DATA_V1)
+ goto drop;
+
+ /* unknown or control packet: let it bubble up to userspace */
+ return 1;
+ }
+
+ peer_id = ovpn_peer_id_from_skb(skb, sizeof(struct udphdr));
+ /* some OpenVPN server implementations send data packets with the
+ * peer-id set to undef. In this case we skip the peer lookup by peer-id
+ * and we try with the transport address
+ */
+ if (peer_id != OVPN_PEER_ID_UNDEF) {
+ peer = ovpn_peer_get_by_id(ovpn, peer_id);
+ if (!peer) {
+ net_err_ratelimited("%s: received data from unknown peer (id: %d)\n",
+ __func__, peer_id);
+ goto drop;
+ }
+ }
+
+ if (!peer) {
+ /* data packet with undef peer-id */
+ peer = ovpn_peer_get_by_transp_addr(ovpn, skb);
+ if (unlikely(!peer)) {
+ net_dbg_ratelimited("%s: received data with undef peer-id from unknown source\n",
+ __func__);
+ goto drop;
+ }
+ }
+
+ /* pop off outer UDP header */
+ __skb_pull(skb, sizeof(struct udphdr));
+ ovpn_recv(peer, skb);
+ return 0;
+
+drop:
+ if (peer)
+ ovpn_peer_put(peer);
+ dev_core_stats_rx_dropped_inc(ovpn->dev);
+ kfree_skb(skb);
+ return 0;
+}
+
/**
* ovpn_udp4_output - send IPv4 packet over udp socket
* @ovpn: the openvpn instance
@@ -257,8 +342,13 @@ void ovpn_udp_send_skb(struct ovpn_struct *ovpn, struct ovpn_peer *peer,
*/
int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_struct *ovpn)
{
+ struct udp_tunnel_sock_cfg cfg = {
+ .sk_user_data = ovpn,
+ .encap_type = UDP_ENCAP_OVPNINUDP,
+ .encap_rcv = ovpn_udp_encap_recv,
+ };
struct ovpn_socket *old_data;
- int ret = 0;
+ int ret;
/* sanity check */
if (sock->sk->sk_protocol != IPPROTO_UDP) {
@@ -272,6 +362,7 @@ int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_struct *ovpn)
if (!old_data) {
/* socket is currently unused - we can take it */
rcu_read_unlock();
+ setup_udp_tunnel_sock(sock_net(sock->sk), sock, &cfg);
return 0;
}
@@ -300,3 +391,14 @@ int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_struct *ovpn)
return ret;
}
+
+/**
+ * ovpn_udp_socket_detach - clean udp-tunnel status for this socket
+ * @sock: the socket to clean
+ */
+void ovpn_udp_socket_detach(struct socket *sock)
+{
+ struct udp_tunnel_sock_cfg cfg = { };
+
+ setup_udp_tunnel_sock(sock_net(sock->sk), sock, &cfg);
+}
@@ -18,8 +18,9 @@ struct sk_buff;
struct socket;
int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_struct *ovpn);
-
+void ovpn_udp_socket_detach(struct socket *sock);
void ovpn_udp_send_skb(struct ovpn_struct *ovpn, struct ovpn_peer *peer,
struct sk_buff *skb);
+struct ovpn_struct *ovpn_from_udp_sock(struct sock *sk);
#endif /* _NET_OVPN_UDP_H_ */
Packets received over the socket are forwarded to the user device. Implementation is UDP only. TCP will be added by a later patch. Note: no decryption/decapsulation exists yet, packets are forwarded as they arrive without much processing. Signed-off-by: Antonio Quartulli <antonio@openvpn.net> --- drivers/net/ovpn/io.c | 66 ++++++++++++++++++++- drivers/net/ovpn/io.h | 2 +- drivers/net/ovpn/main.c | 9 ++- drivers/net/ovpn/ovpnstruct.h | 3 + drivers/net/ovpn/proto.h | 75 ++++++++++++++++++++++++ drivers/net/ovpn/skb.h | 3 - drivers/net/ovpn/socket.c | 24 ++++++++ drivers/net/ovpn/udp.c | 104 +++++++++++++++++++++++++++++++++- drivers/net/ovpn/udp.h | 3 +- 9 files changed, 281 insertions(+), 8 deletions(-) create mode 100644 drivers/net/ovpn/proto.h