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 | 64 ++++++++++++++++++++++++++++++++- drivers/net/ovpn/io.h | 2 ++ drivers/net/ovpn/main.c | 13 ++++++- drivers/net/ovpn/ovpnstruct.h | 3 ++ drivers/net/ovpn/proto.h | 50 +++++++++++++++++++++++++- drivers/net/ovpn/socket.c | 32 +++++++++++++++++ drivers/net/ovpn/udp.c | 83 ++++++++++++++++++++++++++++++++++++++++++- drivers/net/ovpn/udp.h | 2 +- 8 files changed, 244 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c index 2a3dbc723813a14070159318097755cc7ea3f216..9f5c6b06c79681048f750fce89e9683da41ea642 100644 --- a/drivers/net/ovpn/io.c +++ b/drivers/net/ovpn/io.c @@ -9,15 +9,77 @@
#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" #include "socket.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) +{ + unsigned int pkt_len; + int ret; + + /* we can't guarantee the packet wasn't corrupted before entering the + * VPN, therefore we give other layers a chance to check that + */ + skb->ip_summed = CHECKSUM_NONE; + + /* skb hash for transport packet no longer valid after decapsulation */ + skb_clear_hash(skb); + + /* post-decrypt scrub -- prepare to inject encapsulated packet onto the + * interface, based on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_reset_inner_headers(skb); + + /* cause packet to be "received" by the interface */ + pkt_len = skb->len; + ret = gro_cells_receive(&peer->ovpn->gro_cells, skb); + if (likely(ret == NET_RX_SUCCESS)) + /* update RX stats with the size of decrypted packet */ + dev_sw_netstats_rx_add(peer->ovpn->dev, pkt_len); +} + +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); + ovpn_peer_put(peer); + kfree_skb(skb); +} + +/* RX path entry point: decrypt packet 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; diff --git a/drivers/net/ovpn/io.h b/drivers/net/ovpn/io.h index a90537e9af6c0d2f38da229bdc2d8c639f2d11d1..b3830b787e16f3bdcaaff94e5bbe89be3e1006fe 100644 --- a/drivers/net/ovpn/io.h +++ b/drivers/net/ovpn/io.h @@ -21,4 +21,6 @@
netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev);
+void ovpn_recv(struct ovpn_peer *peer, struct sk_buff *skb); + #endif /* _NET_OVPN_OVPN_H_ */ diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c index a2d953dccd2cd9372f486b6f35479fb0180760b8..0dbbcf2faf129651390f47ce6098d5b6e28aa74e 100644 --- a/drivers/net/ovpn/main.c +++ b/drivers/net/ovpn/main.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <linux/netdevice.h> #include <linux/inetdevice.h> +#include <net/gro_cells.h> #include <net/ip.h> #include <net/rtnetlink.h> #include <uapi/linux/if_arp.h> @@ -24,7 +25,16 @@
static int ovpn_net_init(struct net_device *dev) { - return 0; + struct ovpn_priv *ovpn = netdev_priv(dev); + + return gro_cells_init(&ovpn->gro_cells, dev); +} + +static void ovpn_net_uninit(struct net_device *dev) +{ + struct ovpn_priv *ovpn = netdev_priv(dev); + + gro_cells_destroy(&ovpn->gro_cells); }
static int ovpn_net_open(struct net_device *dev) @@ -50,6 +60,7 @@ static int ovpn_net_stop(struct net_device *dev)
static const struct net_device_ops ovpn_netdev_ops = { .ndo_init = ovpn_net_init, + .ndo_uninit = ovpn_net_uninit, .ndo_open = ovpn_net_open, .ndo_stop = ovpn_net_stop, .ndo_start_xmit = ovpn_net_xmit, diff --git a/drivers/net/ovpn/ovpnstruct.h b/drivers/net/ovpn/ovpnstruct.h index a6cfb436f3d0d79a0c438e647f8652021119b0ed..1cca91d869d9e3c722a0933a426255f05daf8097 100644 --- a/drivers/net/ovpn/ovpnstruct.h +++ b/drivers/net/ovpn/ovpnstruct.h @@ -10,6 +10,7 @@ #ifndef _NET_OVPN_OVPNSTRUCT_H_ #define _NET_OVPN_OVPNSTRUCT_H_
+#include <net/gro_cells.h> #include <net/net_trackers.h> #include <uapi/linux/if_link.h> #include <uapi/linux/ovpn.h> @@ -22,6 +23,7 @@ * @mode: device operation mode (i.e. p2p, mp, ..) * @lock: protect this object * @peer: in P2P mode, this is the only remote peer + * @gro_cells: pointer to the Generic Receive Offload cell */ struct ovpn_priv { struct net_device *dev; @@ -30,6 +32,7 @@ struct ovpn_priv { enum ovpn_mode mode; spinlock_t lock; /* protect writing to the ovpn_priv object */ struct ovpn_peer __rcu *peer; + struct gro_cells gro_cells; };
#endif /* _NET_OVPN_OVPNSTRUCT_H_ */ diff --git a/drivers/net/ovpn/proto.h b/drivers/net/ovpn/proto.h index 00bb3725ac7ab7040c97eb012c2639b2d6967de1..34a812869b2e92e8bab0ebb87d46b67c3bbccf9f 100644 --- a/drivers/net/ovpn/proto.h +++ b/drivers/net/ovpn/proto.h @@ -10,6 +10,11 @@ #ifndef _NET_OVPN_PROTO_H_ #define _NET_OVPN_PROTO_H_
+#include "main.h" + +#include <linux/bitfield.h> +#include <linux/skbuff.h> + /* When the OpenVPN protocol is ran in AEAD mode, use * the OpenVPN packet ID as the AEAD nonce: * @@ -34,5 +39,48 @@ #define OVPN_NONCE_WIRE_SIZE (OVPN_NONCE_SIZE - OVPN_NONCE_TAIL_SIZE)
#define OVPN_OPCODE_SIZE 4 /* DATA_V2 opcode size */ +#define OVPN_OPCODE_KEYID_MASK 0x07000000 +#define OVPN_OPCODE_PKTTYPE_MASK 0xF8000000 +#define OVPN_OPCODE_PEERID_MASK 0x00FFFFFF + +/* packet opcodes of interest to us */ +#define OVPN_DATA_V1 6 /* data channel v1 packet */ +#define OVPN_DATA_V2 9 /* data channel v2 packet */ + +#define OVPN_PEER_ID_UNDEF 0x00FFFFFF + +/** + * 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) +{ + u32 opcode = be32_to_cpu(*(__be32 *)(skb->data + offset)); + + return FIELD_GET(OVPN_OPCODE_PKTTYPE_MASK, opcode); +} + +/** + * 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) +{ + u32 opcode = be32_to_cpu(*(__be32 *)(skb->data + offset)); + + return FIELD_GET(OVPN_OPCODE_PEERID_MASK, opcode); +}
-#endif /* _NET_OVPN_PROTO_H_ */ +#endif /* _NET_OVPN_OVPNPROTO_H_ */ diff --git a/drivers/net/ovpn/socket.c b/drivers/net/ovpn/socket.c index b41a95cc154ad50f86e67178a95f16e323880800..ff4b64f743641e04489c88f76293d378e54c8853 100644 --- a/drivers/net/ovpn/socket.c +++ b/drivers/net/ovpn/socket.c @@ -31,6 +31,17 @@ static void ovpn_socket_release_kref(struct kref *kref) struct ovpn_socket *sock = container_of(kref, struct ovpn_socket, refcount);
+ /* UDP sockets are detached in this kref callback because + * we now know for sure that all concurrent users have + * finally gone (refcounter dropped to 0). + * + * Moreover, detachment is performed under lock to prevent + * a concurrent ovpn_socket_new() call with the same socket + * to find the socket still attached but with refcounter 0. + */ + if (sock->sock->sk->sk_protocol == IPPROTO_UDP) + ovpn_udp_socket_detach(sock->sock); + bh_unlock_sock(sock->sock->sk); sockfd_put(sock->sock); kfree_rcu(sock, rcu); @@ -102,6 +113,27 @@ 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_priv *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 diff --git a/drivers/net/ovpn/udp.c b/drivers/net/ovpn/udp.c index 5f2a3790613e7b688001ee65993031436a308b95..5932f8b5dfad1004e9e76e5fabfbb71bd9a94d4d 100644 --- a/drivers/net/ovpn/udp.c +++ b/drivers/net/ovpn/udp.c @@ -23,9 +23,82 @@ #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_priv *ovpn; + struct ovpn_peer *peer; + u32 peer_id; + u8 opcode; + + ovpn = ovpn_from_udp_sock(sk); + if (unlikely(!ovpn)) { + net_err_ratelimited("ovpn: cannot obtain ovpn object from UDP socket\n"); + goto drop_noovpn; + } + + /* 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_OPCODE_SIZE))) { + net_dbg_ratelimited("%s: packet too small from UDP socket\n", + netdev_name(ovpn->dev)); + 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_transp_addr(ovpn, skb); + else + peer = ovpn_peer_get_by_id(ovpn, peer_id); + + if (unlikely(!peer)) + goto drop; + + /* pop off outer UDP header */ + __skb_pull(skb, sizeof(struct udphdr)); + ovpn_recv(peer, skb); + return 0; + +drop: + dev_core_stats_rx_dropped_inc(ovpn->dev); +drop_noovpn: + kfree_skb(skb); + return 0; +} + /** * ovpn_udp4_output - send IPv4 packet over udp socket * @peer: the destination peer @@ -262,8 +335,12 @@ void ovpn_udp_send_skb(struct ovpn_peer *peer, struct sk_buff *skb) */ int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_priv *ovpn) { + struct udp_tunnel_sock_cfg cfg = { + .encap_type = UDP_ENCAP_OVPNINUDP, + .encap_rcv = ovpn_udp_encap_recv, + }; struct ovpn_socket *old_data; - int ret = 0; + int ret;
/* make sure no pre-existing encapsulation handler exists */ rcu_read_lock(); @@ -271,6 +348,7 @@ int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_priv *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; }
@@ -304,4 +382,7 @@ int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_priv *ovpn) */ void ovpn_udp_socket_detach(struct socket *sock) { + struct udp_tunnel_sock_cfg cfg = { }; + + setup_udp_tunnel_sock(sock_net(sock->sk), sock, &cfg); } diff --git a/drivers/net/ovpn/udp.h b/drivers/net/ovpn/udp.h index b4ac15a535c24ec4979db7cb44f682af1b096ccf..90a46821d1e999fea0e1aa0f7de9db65decf71d5 100644 --- a/drivers/net/ovpn/udp.h +++ b/drivers/net/ovpn/udp.h @@ -17,7 +17,7 @@ struct socket;
int ovpn_udp_socket_attach(struct socket *sock, struct ovpn_priv *ovpn); void ovpn_udp_socket_detach(struct socket *sock); - void ovpn_udp_send_skb(struct ovpn_peer *peer, struct sk_buff *skb); +struct ovpn_priv *ovpn_from_udp_sock(struct sock *sk);
#endif /* _NET_OVPN_UDP_H_ */