Add basic infrastructure for handling ovpn interfaces.
Tested-by: Donald Hunter donald.hunter@gmail.com Signed-off-by: Antonio Quartulli antonio@openvpn.net --- Documentation/netlink/specs/rt_link.yaml | 16 ++++++ drivers/net/ovpn/Makefile | 1 + drivers/net/ovpn/io.c | 22 +++++++ drivers/net/ovpn/io.h | 24 ++++++++ drivers/net/ovpn/main.c | 99 ++++++++++++++++++++++++++++++-- drivers/net/ovpn/ovpnpriv.h | 7 +++ drivers/net/ovpn/proto.h | 38 ++++++++++++ include/uapi/linux/if_link.h | 15 +++++ 8 files changed, 217 insertions(+), 5 deletions(-)
diff --git a/Documentation/netlink/specs/rt_link.yaml b/Documentation/netlink/specs/rt_link.yaml index 31238455f8e9d29531884cad4951391fa47ccfaf..a50d9d7d882e7e4f9de29b2a4e7acc602972f6b3 100644 --- a/Documentation/netlink/specs/rt_link.yaml +++ b/Documentation/netlink/specs/rt_link.yaml @@ -938,6 +938,12 @@ definitions: entries: - name: none - name: default + - + name: ovpn-mode + type: enum + entries: + - p2p + - mp
attribute-sets: - @@ -2272,6 +2278,13 @@ attribute-sets: - name: tailroom type: u16 + - + name: linkinfo-ovpn-attrs + attributes: + - + name: mode + type: u8 + enum: ovpn-mode
sub-messages: - @@ -2322,6 +2335,9 @@ sub-messages: - value: netkit attribute-set: linkinfo-netkit-attrs + - + value: ovpn + attribute-set: linkinfo-ovpn-attrs - name: linkinfo-member-data-msg formats: diff --git a/drivers/net/ovpn/Makefile b/drivers/net/ovpn/Makefile index 75ac62bba02937bc49cb2a0dec5ca3cc31a8ee00..0e5f686672fb5052cee5a2c28797b70859514a7f 100644 --- a/drivers/net/ovpn/Makefile +++ b/drivers/net/ovpn/Makefile @@ -8,5 +8,6 @@
obj-$(CONFIG_OVPN) := ovpn.o ovpn-y += main.o +ovpn-y += io.o ovpn-y += netlink.o ovpn-y += netlink-gen.o diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c new file mode 100644 index 0000000000000000000000000000000000000000..4b71c38165d7adbb1a2d1a64d27a13b7f76cfbfe --- /dev/null +++ b/drivers/net/ovpn/io.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0 +/* OpenVPN data channel offload + * + * Copyright (C) 2019-2025 OpenVPN, Inc. + * + * Author: James Yonan james@openvpn.net + * Antonio Quartulli antonio@openvpn.net + */ + +#include <linux/netdevice.h> +#include <linux/skbuff.h> + +#include "io.h" + +/* Send user data to the network + */ +netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev) +{ + skb_tx_error(skb); + kfree_skb(skb); + return NET_XMIT_DROP; +} diff --git a/drivers/net/ovpn/io.h b/drivers/net/ovpn/io.h new file mode 100644 index 0000000000000000000000000000000000000000..afea5f81f5628dcb9afda9a78974bbf6f2101c13 --- /dev/null +++ b/drivers/net/ovpn/io.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* OpenVPN data channel offload + * + * Copyright (C) 2019-2025 OpenVPN, Inc. + * + * Author: James Yonan james@openvpn.net + * Antonio Quartulli antonio@openvpn.net + */ + +#ifndef _NET_OVPN_OVPN_H_ +#define _NET_OVPN_OVPN_H_ + +/* DATA_V2 header size with AEAD encryption */ +#define OVPN_HEAD_ROOM (OVPN_OPCODE_SIZE + OVPN_NONCE_WIRE_SIZE + \ + 16 /* AEAD TAG length */ + \ + max(sizeof(struct udphdr), sizeof(struct tcphdr)) +\ + max(sizeof(struct ipv6hdr), sizeof(struct iphdr))) + +/* max padding required by encryption */ +#define OVPN_MAX_PADDING 16 + +netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev); + +#endif /* _NET_OVPN_OVPN_H_ */ diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c index 28133e7e15e74b8a4a937ed03f70d9f83d7a14c8..b19f1406d87d5a1ed45b00133d642b1ad9f4f6f7 100644 --- a/drivers/net/ovpn/main.c +++ b/drivers/net/ovpn/main.c @@ -10,14 +10,28 @@ #include <linux/genetlink.h> #include <linux/module.h> #include <linux/netdevice.h> +#include <linux/inetdevice.h> +#include <net/ip.h> #include <net/rtnetlink.h> -#include <uapi/linux/ovpn.h> +#include <uapi/linux/if_arp.h>
#include "ovpnpriv.h" #include "main.h" #include "netlink.h" +#include "io.h" +#include "proto.h"
static const struct net_device_ops ovpn_netdev_ops = { + .ndo_start_xmit = ovpn_net_xmit, +}; + +static const struct device_type ovpn_type = { + .name = OVPN_FAMILY_NAME, +}; + +static const struct nla_policy ovpn_policy[IFLA_OVPN_MAX + 1] = { + [IFLA_OVPN_MODE] = NLA_POLICY_RANGE(NLA_U8, OVPN_MODE_P2P, + OVPN_MODE_MP), };
/** @@ -31,44 +45,119 @@ bool ovpn_dev_is_valid(const struct net_device *dev) return dev->netdev_ops == &ovpn_netdev_ops; }
+static void ovpn_setup(struct net_device *dev) +{ + netdev_features_t feat = NETIF_F_SG | NETIF_F_GSO | + NETIF_F_GSO_SOFTWARE | NETIF_F_HIGHDMA; + + dev->needs_free_netdev = true; + + dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS; + + dev->netdev_ops = &ovpn_netdev_ops; + + dev->hard_header_len = 0; + dev->addr_len = 0; + dev->mtu = ETH_DATA_LEN - OVPN_HEAD_ROOM; + dev->min_mtu = IPV4_MIN_MTU; + dev->max_mtu = IP_MAX_MTU - OVPN_HEAD_ROOM; + + dev->type = ARPHRD_NONE; + dev->flags = IFF_POINTOPOINT | IFF_NOARP; + dev->priv_flags |= IFF_NO_QUEUE; + + dev->lltx = true; + dev->features |= feat; + dev->hw_features |= feat; + dev->hw_enc_features |= feat; + + dev->needed_headroom = ALIGN(OVPN_HEAD_ROOM, 4); + dev->needed_tailroom = OVPN_MAX_PADDING; + + SET_NETDEV_DEVTYPE(dev, &ovpn_type); +} + static int ovpn_newlink(struct net_device *dev, struct rtnl_newlink_params *params, struct netlink_ext_ack *extack) { - return -EOPNOTSUPP; + struct ovpn_priv *ovpn = netdev_priv(dev); + struct nlattr **data = params->data; + enum ovpn_mode mode = OVPN_MODE_P2P; + + if (data && data[IFLA_OVPN_MODE]) { + mode = nla_get_u8(data[IFLA_OVPN_MODE]); + netdev_dbg(dev, "setting device mode: %u\n", mode); + } + + ovpn->dev = dev; + ovpn->mode = mode; + + /* turn carrier explicitly off after registration, this way state is + * clearly defined + */ + netif_carrier_off(dev); + + return register_netdevice(dev); +} + +static int ovpn_fill_info(struct sk_buff *skb, const struct net_device *dev) +{ + struct ovpn_priv *ovpn = netdev_priv(dev); + + if (nla_put_u8(skb, IFLA_OVPN_MODE, ovpn->mode)) + return -EMSGSIZE; + + return 0; }
static struct rtnl_link_ops ovpn_link_ops = { .kind = "ovpn", .netns_refund = false, + .priv_size = sizeof(struct ovpn_priv), + .setup = ovpn_setup, + .policy = ovpn_policy, + .maxtype = IFLA_OVPN_MAX, .newlink = ovpn_newlink, .dellink = unregister_netdevice_queue, + .fill_info = ovpn_fill_info, };
static int ovpn_netdev_notifier_call(struct notifier_block *nb, unsigned long state, void *ptr) { struct net_device *dev = netdev_notifier_info_to_dev(ptr); + struct ovpn_priv *ovpn;
if (!ovpn_dev_is_valid(dev)) return NOTIFY_DONE;
+ ovpn = netdev_priv(dev); + switch (state) { case NETDEV_REGISTER: - /* add device to internal list for later destruction upon - * unregistration - */ + ovpn->registered = true; break; case NETDEV_UNREGISTER: + /* twiddle thumbs on netns device moves */ + if (dev->reg_state != NETREG_UNREGISTERING) + break; + /* can be delivered multiple times, so check registered flag, * then destroy the interface */ + if (!ovpn->registered) + return NOTIFY_DONE; + + netif_carrier_off(dev); + ovpn->registered = false; break; case NETDEV_POST_INIT: case NETDEV_GOING_DOWN: case NETDEV_DOWN: case NETDEV_UP: case NETDEV_PRE_UP: + break; default: return NOTIFY_DONE; } diff --git a/drivers/net/ovpn/ovpnpriv.h b/drivers/net/ovpn/ovpnpriv.h index f9322536b06d6baa5524de57cd7d69f5ecbbd194..33c2a41edf9b3204e8aebd2679649cb7158f05f2 100644 --- a/drivers/net/ovpn/ovpnpriv.h +++ b/drivers/net/ovpn/ovpnpriv.h @@ -10,12 +10,19 @@ #ifndef _NET_OVPN_OVPNSTRUCT_H_ #define _NET_OVPN_OVPNSTRUCT_H_
+#include <uapi/linux/if_link.h> +#include <uapi/linux/ovpn.h> + /** * struct ovpn_priv - per ovpn interface state * @dev: the actual netdev representing the tunnel + * @registered: whether dev is still registered with netdev or not + * @mode: device operation mode (i.e. p2p, mp, ..) */ struct ovpn_priv { struct net_device *dev; + bool registered; + enum ovpn_mode mode; };
#endif /* _NET_OVPN_OVPNSTRUCT_H_ */ diff --git a/drivers/net/ovpn/proto.h b/drivers/net/ovpn/proto.h new file mode 100644 index 0000000000000000000000000000000000000000..5f95a78bebd3702868ffeeab3ea4938e957d568c --- /dev/null +++ b/drivers/net/ovpn/proto.h @@ -0,0 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* OpenVPN data channel offload + * + * Copyright (C) 2020-2025 OpenVPN, Inc. + * + * Author: Antonio Quartulli antonio@openvpn.net + * James Yonan james@openvpn.net + */ + +#ifndef _NET_OVPN_PROTO_H_ +#define _NET_OVPN_PROTO_H_ + +/* When the OpenVPN protocol is ran in AEAD mode, use + * the OpenVPN packet ID as the AEAD nonce: + * + * 00000005 521c3b01 4308c041 + * [seq # ] [ nonce_tail ] + * [ 12-byte full IV ] -> OVPN_NONCE_SIZE + * [4-bytes -> OVPN_NONCE_WIRE_SIZE + * on wire] + */ + +/* nonce size (96bits) as required by AEAD ciphers */ +#define OVPN_NONCE_SIZE 12 +/* last 8 bytes of AEAD nonce: provided by userspace and usually derived + * from key material generated during TLS handshake + */ +#define OVPN_NONCE_TAIL_SIZE 8 + +/* OpenVPN nonce size reduced by 8-byte nonce tail -- this is the + * size of the AEAD Associated Data (AD) sent over the wire + * and is normally the head of the IV + */ +#define OVPN_NONCE_WIRE_SIZE (OVPN_NONCE_SIZE - OVPN_NONCE_TAIL_SIZE) + +#define OVPN_OPCODE_SIZE 4 /* DATA_V2 opcode size */ + +#endif /* _NET_OVPN_PROTO_H_ */ diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h index 318386cc5b0d19ed6a37734feffb450353dd9440..3ad2d5d9803479a10a6b2cfab2df98ce0f823926 100644 --- a/include/uapi/linux/if_link.h +++ b/include/uapi/linux/if_link.h @@ -1986,4 +1986,19 @@ enum {
#define IFLA_DSA_MAX (__IFLA_DSA_MAX - 1)
+/* OVPN section */ + +enum ovpn_mode { + OVPN_MODE_P2P, + OVPN_MODE_MP, +}; + +enum { + IFLA_OVPN_UNSPEC, + IFLA_OVPN_MODE, + __IFLA_OVPN_MAX, +}; + +#define IFLA_OVPN_MAX (__IFLA_OVPN_MAX - 1) + #endif /* _UAPI_LINUX_IF_LINK_H */