Add basic infrastructure for handling ovpn interfaces.
Signed-off-by: Antonio Quartulli antonio@openvpn.net --- drivers/net/ovpn/main.c | 115 ++++++++++++++++++++++++++++++++++++++++-- drivers/net/ovpn/main.h | 7 +++ drivers/net/ovpn/ovpnstruct.h | 8 +++ drivers/net/ovpn/packet.h | 40 +++++++++++++++ include/uapi/linux/if_link.h | 15 ++++++ 5 files changed, 180 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c index d5bdb0055f4dd3a6e32dc6e792bed1e7fd59e101..eead7677b8239eb3c48bb26ca95492d88512b8d4 100644 --- a/drivers/net/ovpn/main.c +++ b/drivers/net/ovpn/main.c @@ -10,18 +10,52 @@ #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 "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."
+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, +}; + +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), +}; + /** * ovpn_dev_is_valid - check if the netdevice is of type 'ovpn' * @dev: the interface to check @@ -33,16 +67,76 @@ bool ovpn_dev_is_valid(const struct net_device *dev) return dev->netdev_ops->ndo_start_xmit == ovpn_net_xmit; }
+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->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->priv_flags |= IFF_NO_QUEUE; + + 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; + + SET_NETDEV_DEVTYPE(dev, &ovpn_type); +} + static int ovpn_newlink(struct net *src_net, struct net_device *dev, struct nlattr *tb[], struct nlattr *data[], struct netlink_ext_ack *extack) { - return -EOPNOTSUPP; + struct ovpn_struct *ovpn = netdev_priv(dev); + 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 struct rtnl_link_ops ovpn_link_ops = { .kind = OVPN_FAMILY_NAME, .netns_refund = false, + .priv_size = sizeof(struct ovpn_struct), + .setup = ovpn_setup, + .policy = ovpn_policy, + .maxtype = IFLA_OVPN_MAX, .newlink = ovpn_newlink, .dellink = unregister_netdevice_queue, }; @@ -51,26 +145,37 @@ 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; + + 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/main.h b/drivers/net/ovpn/main.h index a3215316c49bfcdf2496590bac878f145b8b27fd..0740a05070a817e0daea7b63a1f4fcebd274eb37 100644 --- a/drivers/net/ovpn/main.h +++ b/drivers/net/ovpn/main.h @@ -12,4 +12,11 @@
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 e3e4df6418b081436378fc51d98db5bd7b5d1fbe..211df871538d34fdff90d182f21a0b0fb11b28ad 100644 --- a/drivers/net/ovpn/ovpnstruct.h +++ b/drivers/net/ovpn/ovpnstruct.h @@ -11,15 +11,23 @@ #define _NET_OVPN_OVPNSTRUCT_H_
#include <net/net_trackers.h> +#include <uapi/linux/if_link.h> +#include <uapi/linux/ovpn.h>
/** * struct ovpn_struct - per ovpn interface state * @dev: the actual netdev representing the tunnel * @dev_tracker: reference tracker for associated dev + * @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; netdevice_tracker dev_tracker; + 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_ */ diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h index 8516c1ccd57a7c7634a538fe3ac16c858f647420..84d294aab20b79b8e9cb9b736a074105c99338f3 100644 --- a/include/uapi/linux/if_link.h +++ b/include/uapi/linux/if_link.h @@ -1975,4 +1975,19 @@ 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 */