Add basic infrastructure for handling ovpn interfaces.
Signed-off-by: Antonio Quartulli antonio@openvpn.net --- drivers/net/ovpn/main.c | 155 +++++++++++++++++++++++++++++++++++++++++- drivers/net/ovpn/main.h | 10 +++ drivers/net/ovpn/ovpnstruct.h | 8 +++ drivers/net/ovpn/packet.h | 40 +++++++++++ 4 files changed, 210 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c index 0274ddddbcd25080d7f85347f79aad0259771508..12f6258f94c8baef855e2ce90cf70380d5af5ca9 100644 --- a/drivers/net/ovpn/main.c +++ b/drivers/net/ovpn/main.c @@ -10,19 +10,58 @@ #include <linux/genetlink.h> #include <linux/module.h> #include <linux/netdevice.h> +#include <linux/inetdevice.h> #include <linux/version.h> +#include <net/ip.h> #include <net/rtnetlink.h> +#include <uapi/linux/if_arp.h> #include <uapi/linux/ovpn.h>
#include "ovpnstruct.h" #include "main.h" #include "netlink.h" #include "io.h" +#include "packet.h"
/* Driver info */ #define DRV_DESCRIPTION "OpenVPN data channel offload (ovpn)" #define DRV_COPYRIGHT "(C) 2020-2024 OpenVPN, Inc."
+/** + * ovpn_struct_init - Initialize the netdevice private area + * @dev: the device to initialize + * @mode: device operation mode (i.e. p2p, mp, ..) + */ +static void ovpn_struct_init(struct net_device *dev, enum ovpn_mode mode) +{ + struct ovpn_struct *ovpn = netdev_priv(dev); + + ovpn->dev = dev; + ovpn->mode = mode; +} + +static void ovpn_struct_free(struct net_device *net) +{ +} + +static int ovpn_net_open(struct net_device *dev) +{ + netif_tx_start_all_queues(dev); + return 0; +} + +static int ovpn_net_stop(struct net_device *dev) +{ + netif_tx_stop_all_queues(dev); + return 0; +} + +static const struct net_device_ops ovpn_netdev_ops = { + .ndo_open = ovpn_net_open, + .ndo_stop = ovpn_net_stop, + .ndo_start_xmit = ovpn_net_xmit, +}; + /** * ovpn_dev_is_valid - check if the netdevice is of type 'ovpn' * @dev: the interface to check @@ -40,30 +79,140 @@ static struct rtnl_link_ops ovpn_link_ops = { .dellink = unregister_netdevice_queue, };
+static void ovpn_setup(struct net_device *dev) +{ + /* compute the overhead considering AEAD encryption */ + const int overhead = sizeof(u32) + NONCE_WIRE_SIZE + 16 + + sizeof(struct udphdr) + + max(sizeof(struct ipv6hdr), sizeof(struct iphdr)); + + netdev_features_t feat = NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_RXCSUM | + 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->rtnl_link_ops = &ovpn_link_ops; + + dev->priv_destructor = ovpn_struct_free; + + dev->hard_header_len = 0; + dev->addr_len = 0; + dev->mtu = ETH_DATA_LEN - overhead; + dev->min_mtu = IPV4_MIN_MTU; + dev->max_mtu = IP_MAX_MTU - overhead; + + dev->type = ARPHRD_NONE; + dev->flags = IFF_POINTOPOINT | IFF_NOARP; + + dev->lltx = true; + dev->features |= feat; + dev->hw_features |= feat; + dev->hw_enc_features |= feat; + + dev->needed_headroom = OVPN_HEAD_ROOM; + dev->needed_tailroom = OVPN_MAX_PADDING; +} + +/** + * ovpn_iface_create - create and initialize a new 'ovpn' netdevice + * @name: the name of the new device + * @mode: the OpenVPN mode to set this device to + * @net: the netns this device should be created in + * + * A new netdevice is created and registered. + * Its private area is initialized with an empty ovpn_struct object. + * + * Return: a pointer to the new device on success or a negative error code + * otherwise + */ +struct net_device *ovpn_iface_create(const char *name, enum ovpn_mode mode, + struct net *net) +{ + struct net_device *dev; + int ret; + + dev = alloc_netdev(sizeof(struct ovpn_struct), name, NET_NAME_USER, + ovpn_setup); + if (!dev) + return ERR_PTR(-ENOMEM); + + dev_net_set(dev, net); + ovpn_struct_init(dev, mode); + + rtnl_lock(); + ret = register_netdevice(dev); + if (ret < 0) { + netdev_err(dev, "cannot register interface: %d\n", ret); + rtnl_unlock(); + goto err; + } + /* turn carrier explicitly off after registration, this way state is + * clearly defined + */ + netif_carrier_off(dev); + rtnl_unlock(); + + return dev; + +err: + free_netdev(dev); + return ERR_PTR(ret); +} + +/** + * ovpn_iface_destruct - tear down netdevice + * @ovpn: the ovpn instance objected related to the interface to tear down + * + * This function takes care of tearing down an ovpn device and can be invoked + * internally or upon UNREGISTER netdev event + */ +void ovpn_iface_destruct(struct ovpn_struct *ovpn) +{ + ASSERT_RTNL(); + + netif_carrier_off(ovpn->dev); + + ovpn->registered = false; +} + 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_struct *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; + + ovpn_iface_destruct(ovpn); 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/main.h b/drivers/net/ovpn/main.h index a3215316c49bfcdf2496590bac878f145b8b27fd..4dfcba9deb590bbf119f51a40dff1517fe227b22 100644 --- a/drivers/net/ovpn/main.h +++ b/drivers/net/ovpn/main.h @@ -10,6 +10,16 @@ #ifndef _NET_OVPN_MAIN_H_ #define _NET_OVPN_MAIN_H_
+struct net_device *ovpn_iface_create(const char *name, enum ovpn_mode mode, + struct net *net); +void ovpn_iface_destruct(struct ovpn_struct *ovpn); bool ovpn_dev_is_valid(const struct net_device *dev);
+#define SKB_HEADER_LEN \ + (max(sizeof(struct iphdr), sizeof(struct ipv6hdr)) + \ + sizeof(struct udphdr) + NET_SKB_PAD) + +#define OVPN_HEAD_ROOM ALIGN(16 + SKB_HEADER_LEN, 4) +#define OVPN_MAX_PADDING 16 + #endif /* _NET_OVPN_MAIN_H_ */ diff --git a/drivers/net/ovpn/ovpnstruct.h b/drivers/net/ovpn/ovpnstruct.h index ff248cad1401d00c5bf0aadf9341e40d0a4aee4b..ee05b8a2c61d7c5887e80c7f79e15a1336d99644 100644 --- a/drivers/net/ovpn/ovpnstruct.h +++ b/drivers/net/ovpn/ovpnstruct.h @@ -10,12 +10,20 @@ #ifndef _NET_OVPN_OVPNSTRUCT_H_ #define _NET_OVPN_OVPNSTRUCT_H_
+#include <uapi/linux/ovpn.h> + /** * struct ovpn_struct - 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, ..) + * @dev_list: entry for the module wide device list */ struct ovpn_struct { struct net_device *dev; + bool registered; + enum ovpn_mode mode; + struct list_head dev_list; };
#endif /* _NET_OVPN_OVPNSTRUCT_H_ */ diff --git a/drivers/net/ovpn/packet.h b/drivers/net/ovpn/packet.h new file mode 100644 index 0000000000000000000000000000000000000000..7ed146f5932a25f448af6da58738a7eae81007fe --- /dev/null +++ b/drivers/net/ovpn/packet.h @@ -0,0 +1,40 @@ +/* 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_PACKET_H_ +#define _NET_OVPN_PACKET_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 ] -> NONCE_SIZE + * [4-bytes -> NONCE_WIRE_SIZE + * on wire] + */ + +/* OpenVPN nonce size */ +#define NONCE_SIZE 12 + +/* 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 NONCE_WIRE_SIZE (NONCE_SIZE - sizeof(struct ovpn_nonce_tail)) + +/* Last 8 bytes of AEAD nonce + * Provided by userspace and usually derived from + * key material generated during TLS handshake + */ +struct ovpn_nonce_tail { + u8 u8[OVPN_NONCE_TAIL_SIZE]; +}; + +#endif /* _NET_OVPN_PACKET_H_ */