--- /dev/null
+/*
+ * L2TP core.
+ *
+ * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
+ *
+ * This file contains some code of the original L2TPv2 pppol2tp
+ * driver, which has the following copyright:
+ *
+ * Authors: Martijn van Oosterhout <kleptog@svana.org>
+ * James Chapman (jchapman@katalix.com)
+ * Contributors:
+ * Michal Ostrowski <mostrows@speakeasy.net>
+ * Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
+ * David S. Miller (davem@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <linux/rculist.h>
+#include <linux/uaccess.h>
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/kthread.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/jiffies.h>
+
+#include <linux/netdevice.h>
+#include <linux/net.h>
+#include <linux/inetdevice.h>
+#include <linux/skbuff.h>
+#include <linux/init.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/l2tp.h>
+#include <linux/hash.h>
+#include <linux/sort.h>
+#include <linux/file.h>
+#include <linux/nsproxy.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/dst.h>
+#include <net/ip.h>
+#include <net/udp.h>
+#include <net/udp_tunnel.h>
+#include <net/inet_common.h>
+#include <net/xfrm.h>
+#include <net/protocol.h>
+#include <net/inet6_connection_sock.h>
+#include <net/inet_ecn.h>
+#include <net/ip6_route.h>
+#include <net/ip6_checksum.h>
+
+#include <asm/byteorder.h>
+#include <linux/atomic.h>
+
+#include "l2tp_core.h"
+
+#define L2TP_DRV_VERSION "V2.0"
+
+/* L2TP header constants */
+#define L2TP_HDRFLAG_T 0x8000
+#define L2TP_HDRFLAG_L 0x4000
+#define L2TP_HDRFLAG_S 0x0800
+#define L2TP_HDRFLAG_O 0x0200
+#define L2TP_HDRFLAG_P 0x0100
+
+#define L2TP_HDR_VER_MASK 0x000F
+#define L2TP_HDR_VER_2 0x0002
+#define L2TP_HDR_VER_3 0x0003
+
+/* L2TPv3 default L2-specific sublayer */
+#define L2TP_SLFLAG_S 0x40000000
+#define L2TP_SL_SEQ_MASK 0x00ffffff
+
+#define L2TP_HDR_SIZE_SEQ 10
+#define L2TP_HDR_SIZE_NOSEQ 6
+
+/* Default trace flags */
+#define L2TP_DEFAULT_DEBUG_FLAGS 0
+
+/* Private data stored for received packets in the skb.
+ */
+struct l2tp_skb_cb {
+ u32 ns;
+ u16 has_seq;
+ u16 length;
+ unsigned long expires;
+};
+
+#define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
+
+static atomic_t l2tp_tunnel_count;
+static atomic_t l2tp_session_count;
+static struct workqueue_struct *l2tp_wq;
+
+/* per-net private data for this module */
+static unsigned int l2tp_net_id;
+struct l2tp_net {
+ struct list_head l2tp_tunnel_list;
+ spinlock_t l2tp_tunnel_list_lock;
+ struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
+ spinlock_t l2tp_session_hlist_lock;
+};
+
+static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
+
+static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
+{
+ return sk->sk_user_data;
+}
+
+static inline struct l2tp_net *l2tp_pernet(struct net *net)
+{
+ BUG_ON(!net);
+
+ return net_generic(net, l2tp_net_id);
+}
+
+/* Tunnel reference counts. Incremented per session that is added to
+ * the tunnel.
+ */
+static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
+{
+ atomic_inc(&tunnel->ref_count);
+}
+
+static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
+{
+ if (atomic_dec_and_test(&tunnel->ref_count))
+ l2tp_tunnel_free(tunnel);
+}
+#ifdef L2TP_REFCNT_DEBUG
+#define l2tp_tunnel_inc_refcount(_t) \
+do { \
+ pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", \
+ __func__, __LINE__, (_t)->name, \
+ atomic_read(&_t->ref_count)); \
+ l2tp_tunnel_inc_refcount_1(_t); \
+} while (0)
+#define l2tp_tunnel_dec_refcount(_t) \
+do { \
+ pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", \
+ __func__, __LINE__, (_t)->name, \
+ atomic_read(&_t->ref_count)); \
+ l2tp_tunnel_dec_refcount_1(_t); \
+} while (0)
+#else
+#define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
+#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
+#endif
+
+/* Session hash global list for L2TPv3.
+ * The session_id SHOULD be random according to RFC3931, but several
+ * L2TP implementations use incrementing session_ids. So we do a real
+ * hash on the session_id, rather than a simple bitmask.
+ */
+static inline struct hlist_head *
+l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
+{
+ return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
+
+}
+
+/* Lookup the tunnel socket, possibly involving the fs code if the socket is
+ * owned by userspace. A struct sock returned from this function must be
+ * released using l2tp_tunnel_sock_put once you're done with it.
+ */
+static struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
+{
+ int err = 0;
+ struct socket *sock = NULL;
+ struct sock *sk = NULL;
+
+ if (!tunnel)
+ goto out;
+
+ if (tunnel->fd >= 0) {
+ /* Socket is owned by userspace, who might be in the process
+ * of closing it. Look the socket up using the fd to ensure
+ * consistency.
+ */
+ sock = sockfd_lookup(tunnel->fd, &err);
+ if (sock)
+ sk = sock->sk;
+ } else {
+ /* Socket is owned by kernelspace */
+ sk = tunnel->sock;
+ sock_hold(sk);
+ }
+
+out:
+ return sk;
+}
+
+/* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
+static void l2tp_tunnel_sock_put(struct sock *sk)
+{
+ struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
+ if (tunnel) {
+ if (tunnel->fd >= 0) {
+ /* Socket is owned by userspace */
+ sockfd_put(sk->sk_socket);
+ }
+ sock_put(sk);
+ }
+ sock_put(sk);
+}
+
+/* Lookup a session by id in the global session list
+ */
+static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
+{
+ struct l2tp_net *pn = l2tp_pernet(net);
+ struct hlist_head *session_list =
+ l2tp_session_id_hash_2(pn, session_id);
+ struct l2tp_session *session;
+
+ rcu_read_lock_bh();
+ hlist_for_each_entry_rcu(session, session_list, global_hlist) {
+ if (session->session_id == session_id) {
+ rcu_read_unlock_bh();
+ return session;
+ }
+ }
+ rcu_read_unlock_bh();
+
+ return NULL;
+}
+
+/* Session hash list.
+ * The session_id SHOULD be random according to RFC2661, but several
+ * L2TP implementations (Cisco and Microsoft) use incrementing
+ * session_ids. So we do a real hash on the session_id, rather than a
+ * simple bitmask.
+ */
+static inline struct hlist_head *
+l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
+{
+ return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
+}
+
+/* Lookup a session by id
+ */
+struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
+{
+ struct hlist_head *session_list;
+ struct l2tp_session *session;
+
+ /* In L2TPv3, session_ids are unique over all tunnels and we
+ * sometimes need to look them up before we know the
+ * tunnel.
+ */
+ if (tunnel == NULL)
+ return l2tp_session_find_2(net, session_id);
+
+ session_list = l2tp_session_id_hash(tunnel, session_id);
+ read_lock_bh(&tunnel->hlist_lock);
+ hlist_for_each_entry(session, session_list, hlist) {
+ if (session->session_id == session_id) {
+ read_unlock_bh(&tunnel->hlist_lock);
+ return session;
+ }
+ }
+ read_unlock_bh(&tunnel->hlist_lock);
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_find);
+
+struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
+{
+ int hash;
+ struct l2tp_session *session;
+ int count = 0;
+
+ read_lock_bh(&tunnel->hlist_lock);
+ for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
+ hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
+ if (++count > nth) {
+ read_unlock_bh(&tunnel->hlist_lock);
+ return session;
+ }
+ }
+ }
+
+ read_unlock_bh(&tunnel->hlist_lock);
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
+
+/* Lookup a session by interface name.
+ * This is very inefficient but is only used by management interfaces.
+ */
+struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
+{
+ struct l2tp_net *pn = l2tp_pernet(net);
+ int hash;
+ struct l2tp_session *session;
+
+ rcu_read_lock_bh();
+ for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
+ hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
+ if (!strcmp(session->ifname, ifname)) {
+ rcu_read_unlock_bh();
+ return session;
+ }
+ }
+ }
+
+ rcu_read_unlock_bh();
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
+
+/* Lookup a tunnel by id
+ */
+struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
+{
+ struct l2tp_tunnel *tunnel;
+ struct l2tp_net *pn = l2tp_pernet(net);
+
+ rcu_read_lock_bh();
+ list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
+ if (tunnel->tunnel_id == tunnel_id) {
+ rcu_read_unlock_bh();
+ return tunnel;
+ }
+ }
+ rcu_read_unlock_bh();
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
+
+struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
+{
+ struct l2tp_net *pn = l2tp_pernet(net);
+ struct l2tp_tunnel *tunnel;
+ int count = 0;
+
+ rcu_read_lock_bh();
+ list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
+ if (++count > nth) {
+ rcu_read_unlock_bh();
+ return tunnel;
+ }
+ }
+
+ rcu_read_unlock_bh();
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
+
+/*****************************************************************************
+ * Receive data handling
+ *****************************************************************************/
+
+/* Queue a skb in order. We come here only if the skb has an L2TP sequence
+ * number.
+ */
+static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
+{
+ struct sk_buff *skbp;
+ struct sk_buff *tmp;
+ u32 ns = L2TP_SKB_CB(skb)->ns;
+
+ spin_lock_bh(&session->reorder_q.lock);
+ skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
+ if (L2TP_SKB_CB(skbp)->ns > ns) {
+ __skb_queue_before(&session->reorder_q, skbp, skb);
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
+ session->name, ns, L2TP_SKB_CB(skbp)->ns,
+ skb_queue_len(&session->reorder_q));
+ atomic_long_inc(&session->stats.rx_oos_packets);
+ goto out;
+ }
+ }
+
+ __skb_queue_tail(&session->reorder_q, skb);
+
+out:
+ spin_unlock_bh(&session->reorder_q.lock);
+}
+
+/* Dequeue a single skb.
+ */
+static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+ int length = L2TP_SKB_CB(skb)->length;
+
+ /* We're about to requeue the skb, so return resources
+ * to its current owner (a socket receive buffer).
+ */
+ skb_orphan(skb);
+
+ atomic_long_inc(&tunnel->stats.rx_packets);
+ atomic_long_add(length, &tunnel->stats.rx_bytes);
+ atomic_long_inc(&session->stats.rx_packets);
+ atomic_long_add(length, &session->stats.rx_bytes);
+
+ if (L2TP_SKB_CB(skb)->has_seq) {
+ /* Bump our Nr */
+ session->nr++;
+ session->nr &= session->nr_max;
+
+ l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
+ session->name, session->nr);
+ }
+
+ /* call private receive handler */
+ if (session->recv_skb != NULL)
+ (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
+ else
+ kfree_skb(skb);
+
+ if (session->deref)
+ (*session->deref)(session);
+}
+
+/* Dequeue skbs from the session's reorder_q, subject to packet order.
+ * Skbs that have been in the queue for too long are simply discarded.
+ */
+static void l2tp_recv_dequeue(struct l2tp_session *session)
+{
+ struct sk_buff *skb;
+ struct sk_buff *tmp;
+
+ /* If the pkt at the head of the queue has the nr that we
+ * expect to send up next, dequeue it and any other
+ * in-sequence packets behind it.
+ */
+start:
+ spin_lock_bh(&session->reorder_q.lock);
+ skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
+ if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
+ atomic_long_inc(&session->stats.rx_seq_discards);
+ atomic_long_inc(&session->stats.rx_errors);
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
+ session->name, L2TP_SKB_CB(skb)->ns,
+ L2TP_SKB_CB(skb)->length, session->nr,
+ skb_queue_len(&session->reorder_q));
+ session->reorder_skip = 1;
+ __skb_unlink(skb, &session->reorder_q);
+ kfree_skb(skb);
+ if (session->deref)
+ (*session->deref)(session);
+ continue;
+ }
+
+ if (L2TP_SKB_CB(skb)->has_seq) {
+ if (session->reorder_skip) {
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: advancing nr to next pkt: %u -> %u",
+ session->name, session->nr,
+ L2TP_SKB_CB(skb)->ns);
+ session->reorder_skip = 0;
+ session->nr = L2TP_SKB_CB(skb)->ns;
+ }
+ if (L2TP_SKB_CB(skb)->ns != session->nr) {
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
+ session->name, L2TP_SKB_CB(skb)->ns,
+ L2TP_SKB_CB(skb)->length, session->nr,
+ skb_queue_len(&session->reorder_q));
+ goto out;
+ }
+ }
+ __skb_unlink(skb, &session->reorder_q);
+
+ /* Process the skb. We release the queue lock while we
+ * do so to let other contexts process the queue.
+ */
+ spin_unlock_bh(&session->reorder_q.lock);
+ l2tp_recv_dequeue_skb(session, skb);
+ goto start;
+ }
+
+out:
+ spin_unlock_bh(&session->reorder_q.lock);
+}
+
+static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
+{
+ u32 nws;
+
+ if (nr >= session->nr)
+ nws = nr - session->nr;
+ else
+ nws = (session->nr_max + 1) - (session->nr - nr);
+
+ return nws < session->nr_window_size;
+}
+
+/* If packet has sequence numbers, queue it if acceptable. Returns 0 if
+ * acceptable, else non-zero.
+ */
+static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
+{
+ if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
+ /* Packet sequence number is outside allowed window.
+ * Discard it.
+ */
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: pkt %u len %d discarded, outside window, nr=%u\n",
+ session->name, L2TP_SKB_CB(skb)->ns,
+ L2TP_SKB_CB(skb)->length, session->nr);
+ goto discard;
+ }
+
+ if (session->reorder_timeout != 0) {
+ /* Packet reordering enabled. Add skb to session's
+ * reorder queue, in order of ns.
+ */
+ l2tp_recv_queue_skb(session, skb);
+ goto out;
+ }
+
+ /* Packet reordering disabled. Discard out-of-sequence packets, while
+ * tracking the number if in-sequence packets after the first OOS packet
+ * is seen. After nr_oos_count_max in-sequence packets, reset the
+ * sequence number to re-enable packet reception.
+ */
+ if (L2TP_SKB_CB(skb)->ns == session->nr) {
+ skb_queue_tail(&session->reorder_q, skb);
+ } else {
+ u32 nr_oos = L2TP_SKB_CB(skb)->ns;
+ u32 nr_next = (session->nr_oos + 1) & session->nr_max;
+
+ if (nr_oos == nr_next)
+ session->nr_oos_count++;
+ else
+ session->nr_oos_count = 0;
+
+ session->nr_oos = nr_oos;
+ if (session->nr_oos_count > session->nr_oos_count_max) {
+ session->reorder_skip = 1;
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: %d oos packets received. Resetting sequence numbers\n",
+ session->name, session->nr_oos_count);
+ }
+ if (!session->reorder_skip) {
+ atomic_long_inc(&session->stats.rx_seq_discards);
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
+ session->name, L2TP_SKB_CB(skb)->ns,
+ L2TP_SKB_CB(skb)->length, session->nr,
+ skb_queue_len(&session->reorder_q));
+ goto discard;
+ }
+ skb_queue_tail(&session->reorder_q, skb);
+ }
+
+out:
+ return 0;
+
+discard:
+ return 1;
+}
+
+/* Do receive processing of L2TP data frames. We handle both L2TPv2
+ * and L2TPv3 data frames here.
+ *
+ * L2TPv2 Data Message Header
+ *
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Tunnel ID | Session ID |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Ns (opt) | Nr (opt) |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Offset Size (opt) | Offset pad... (opt)
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * Data frames are marked by T=0. All other fields are the same as
+ * those in L2TP control frames.
+ *
+ * L2TPv3 Data Message Header
+ *
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | L2TP Session Header |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | L2-Specific Sublayer |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Tunnel Payload ...
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * L2TPv3 Session Header Over IP
+ *
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Session ID |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Cookie (optional, maximum 64 bits)...
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * L2TPv3 L2-Specific Sublayer Format
+ *
+ * 0 1 2 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |x|S|x|x|x|x|x|x| Sequence Number |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * Cookie value, sublayer format and offset (pad) are negotiated with
+ * the peer when the session is set up. Unlike L2TPv2, we do not need
+ * to parse the packet header to determine if optional fields are
+ * present.
+ *
+ * Caller must already have parsed the frame and determined that it is
+ * a data (not control) frame before coming here. Fields up to the
+ * session-id have already been parsed and ptr points to the data
+ * after the session-id.
+ */
+void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
+ unsigned char *ptr, unsigned char *optr, u16 hdrflags,
+ int length, int (*payload_hook)(struct sk_buff *skb))
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+ int offset;
+ u32 ns, nr;
+
+ /* The ref count is increased since we now hold a pointer to
+ * the session. Take care to decrement the refcnt when exiting
+ * this function from now on...
+ */
+ l2tp_session_inc_refcount(session);
+ if (session->ref)
+ (*session->ref)(session);
+
+ /* Parse and check optional cookie */
+ if (session->peer_cookie_len > 0) {
+ if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
+ l2tp_info(tunnel, L2TP_MSG_DATA,
+ "%s: cookie mismatch (%u/%u). Discarding.\n",
+ tunnel->name, tunnel->tunnel_id,
+ session->session_id);
+ atomic_long_inc(&session->stats.rx_cookie_discards);
+ goto discard;
+ }
+ ptr += session->peer_cookie_len;
+ }
+
+ /* Handle the optional sequence numbers. Sequence numbers are
+ * in different places for L2TPv2 and L2TPv3.
+ *
+ * If we are the LAC, enable/disable sequence numbers under
+ * the control of the LNS. If no sequence numbers present but
+ * we were expecting them, discard frame.
+ */
+ ns = nr = 0;
+ L2TP_SKB_CB(skb)->has_seq = 0;
+ if (tunnel->version == L2TP_HDR_VER_2) {
+ if (hdrflags & L2TP_HDRFLAG_S) {
+ ns = ntohs(*(__be16 *) ptr);
+ ptr += 2;
+ nr = ntohs(*(__be16 *) ptr);
+ ptr += 2;
+
+ /* Store L2TP info in the skb */
+ L2TP_SKB_CB(skb)->ns = ns;
+ L2TP_SKB_CB(skb)->has_seq = 1;
+
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: recv data ns=%u, nr=%u, session nr=%u\n",
+ session->name, ns, nr, session->nr);
+ }
+ } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
+ u32 l2h = ntohl(*(__be32 *) ptr);
+
+ if (l2h & 0x40000000) {
+ ns = l2h & 0x00ffffff;
+
+ /* Store L2TP info in the skb */
+ L2TP_SKB_CB(skb)->ns = ns;
+ L2TP_SKB_CB(skb)->has_seq = 1;
+
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: recv data ns=%u, session nr=%u\n",
+ session->name, ns, session->nr);
+ }
+ }
+
+ /* Advance past L2-specific header, if present */
+ ptr += session->l2specific_len;
+
+ if (L2TP_SKB_CB(skb)->has_seq) {
+ /* Received a packet with sequence numbers. If we're the LNS,
+ * check if we sre sending sequence numbers and if not,
+ * configure it so.
+ */
+ if ((!session->lns_mode) && (!session->send_seq)) {
+ l2tp_info(session, L2TP_MSG_SEQ,
+ "%s: requested to enable seq numbers by LNS\n",
+ session->name);
+ session->send_seq = -1;
+ l2tp_session_set_header_len(session, tunnel->version);
+ }
+ } else {
+ /* No sequence numbers.
+ * If user has configured mandatory sequence numbers, discard.
+ */
+ if (session->recv_seq) {
+ l2tp_warn(session, L2TP_MSG_SEQ,
+ "%s: recv data has no seq numbers when required. Discarding.\n",
+ session->name);
+ atomic_long_inc(&session->stats.rx_seq_discards);
+ goto discard;
+ }
+
+ /* If we're the LAC and we're sending sequence numbers, the
+ * LNS has requested that we no longer send sequence numbers.
+ * If we're the LNS and we're sending sequence numbers, the
+ * LAC is broken. Discard the frame.
+ */
+ if ((!session->lns_mode) && (session->send_seq)) {
+ l2tp_info(session, L2TP_MSG_SEQ,
+ "%s: requested to disable seq numbers by LNS\n",
+ session->name);
+ session->send_seq = 0;
+ l2tp_session_set_header_len(session, tunnel->version);
+ } else if (session->send_seq) {
+ l2tp_warn(session, L2TP_MSG_SEQ,
+ "%s: recv data has no seq numbers when required. Discarding.\n",
+ session->name);
+ atomic_long_inc(&session->stats.rx_seq_discards);
+ goto discard;
+ }
+ }
+
+ /* Session data offset is handled differently for L2TPv2 and
+ * L2TPv3. For L2TPv2, there is an optional 16-bit value in
+ * the header. For L2TPv3, the offset is negotiated using AVPs
+ * in the session setup control protocol.
+ */
+ if (tunnel->version == L2TP_HDR_VER_2) {
+ /* If offset bit set, skip it. */
+ if (hdrflags & L2TP_HDRFLAG_O) {
+ offset = ntohs(*(__be16 *)ptr);
+ ptr += 2 + offset;
+ }
+ } else
+ ptr += session->offset;
+
+ offset = ptr - optr;
+ if (!pskb_may_pull(skb, offset))
+ goto discard;
+
+ __skb_pull(skb, offset);
+
+ /* If caller wants to process the payload before we queue the
+ * packet, do so now.
+ */
+ if (payload_hook)
+ if ((*payload_hook)(skb))
+ goto discard;
+
+ /* Prepare skb for adding to the session's reorder_q. Hold
+ * packets for max reorder_timeout or 1 second if not
+ * reordering.
+ */
+ L2TP_SKB_CB(skb)->length = length;
+ L2TP_SKB_CB(skb)->expires = jiffies +
+ (session->reorder_timeout ? session->reorder_timeout : HZ);
+
+ /* Add packet to the session's receive queue. Reordering is done here, if
+ * enabled. Saved L2TP protocol info is stored in skb->sb[].
+ */
+ if (L2TP_SKB_CB(skb)->has_seq) {
+ if (l2tp_recv_data_seq(session, skb))
+ goto discard;
+ } else {
+ /* No sequence numbers. Add the skb to the tail of the
+ * reorder queue. This ensures that it will be
+ * delivered after all previous sequenced skbs.
+ */
+ skb_queue_tail(&session->reorder_q, skb);
+ }
+
+ /* Try to dequeue as many skbs from reorder_q as we can. */
+ l2tp_recv_dequeue(session);
+
+ l2tp_session_dec_refcount(session);
+
+ return;
+
+discard:
+ atomic_long_inc(&session->stats.rx_errors);
+ kfree_skb(skb);
+
+ if (session->deref)
+ (*session->deref)(session);
+
+ l2tp_session_dec_refcount(session);
+}
+EXPORT_SYMBOL(l2tp_recv_common);
+
+/* Drop skbs from the session's reorder_q
+ */
+int l2tp_session_queue_purge(struct l2tp_session *session)
+{
+ struct sk_buff *skb = NULL;
+ BUG_ON(!session);
+ BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+ while ((skb = skb_dequeue(&session->reorder_q))) {
+ atomic_long_inc(&session->stats.rx_errors);
+ kfree_skb(skb);
+ if (session->deref)
+ (*session->deref)(session);
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
+
+/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
+ * here. The skb is not on a list when we get here.
+ * Returns 0 if the packet was a data packet and was successfully passed on.
+ * Returns 1 if the packet was not a good data packet and could not be
+ * forwarded. All such packets are passed up to userspace to deal with.
+ */
+static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
+ int (*payload_hook)(struct sk_buff *skb))
+{
+ struct l2tp_session *session = NULL;
+ unsigned char *ptr, *optr;
+ u16 hdrflags;
+ u32 tunnel_id, session_id;
+ u16 version;
+ int length;
+
+ /* UDP has verifed checksum */
+
+ /* UDP always verifies the packet length. */
+ __skb_pull(skb, sizeof(struct udphdr));
+
+ /* Short packet? */
+ if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
+ l2tp_info(tunnel, L2TP_MSG_DATA,
+ "%s: recv short packet (len=%d)\n",
+ tunnel->name, skb->len);
+ goto error;
+ }
+
+ /* Trace packet contents, if enabled */
+ if (tunnel->debug & L2TP_MSG_DATA) {
+ length = min(32u, skb->len);
+ if (!pskb_may_pull(skb, length))
+ goto error;
+
+ pr_debug("%s: recv\n", tunnel->name);
+ print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
+ }
+
+ /* Point to L2TP header */
+ optr = ptr = skb->data;
+
+ /* Get L2TP header flags */
+ hdrflags = ntohs(*(__be16 *) ptr);
+
+ /* Check protocol version */
+ version = hdrflags & L2TP_HDR_VER_MASK;
+ if (version != tunnel->version) {
+ l2tp_info(tunnel, L2TP_MSG_DATA,
+ "%s: recv protocol version mismatch: got %d expected %d\n",
+ tunnel->name, version, tunnel->version);
+ goto error;
+ }
+
+ /* Get length of L2TP packet */
+ length = skb->len;
+
+ /* If type is control packet, it is handled by userspace. */
+ if (hdrflags & L2TP_HDRFLAG_T) {
+ l2tp_dbg(tunnel, L2TP_MSG_DATA,
+ "%s: recv control packet, len=%d\n",
+ tunnel->name, length);
+ goto error;
+ }
+
+ /* Skip flags */
+ ptr += 2;
+
+ if (tunnel->version == L2TP_HDR_VER_2) {
+ /* If length is present, skip it */
+ if (hdrflags & L2TP_HDRFLAG_L)
+ ptr += 2;
+
+ /* Extract tunnel and session ID */
+ tunnel_id = ntohs(*(__be16 *) ptr);
+ ptr += 2;
+ session_id = ntohs(*(__be16 *) ptr);
+ ptr += 2;
+ } else {
+ ptr += 2; /* skip reserved bits */
+ tunnel_id = tunnel->tunnel_id;
+ session_id = ntohl(*(__be32 *) ptr);
+ ptr += 4;
+ }
+
+ /* Find the session context */
+ session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
+ if (!session || !session->recv_skb) {
+ /* Not found? Pass to userspace to deal with */
+ l2tp_info(tunnel, L2TP_MSG_DATA,
+ "%s: no session found (%u/%u). Passing up.\n",
+ tunnel->name, tunnel_id, session_id);
+ goto error;
+ }
+
+ l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
+
+ return 0;
+
+error:
+ /* Put UDP header back */
+ __skb_push(skb, sizeof(struct udphdr));
+
+ return 1;
+}
+
+/* UDP encapsulation receive handler. See net/ipv4/udp.c.
+ * Return codes:
+ * 0 : success.
+ * <0: error
+ * >0: skb should be passed up to userspace as UDP.
+ */
+int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
+{
+ struct l2tp_tunnel *tunnel;
+
+ tunnel = l2tp_sock_to_tunnel(sk);
+ if (tunnel == NULL)
+ goto pass_up;
+
+ l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
+ tunnel->name, skb->len);
+
+ if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
+ goto pass_up_put;
+
+ sock_put(sk);
+ return 0;
+
+pass_up_put:
+ sock_put(sk);
+pass_up:
+ return 1;
+}
+EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
+
+/************************************************************************
+ * Transmit handling
+ ***********************************************************************/
+
+/* Build an L2TP header for the session into the buffer provided.
+ */
+static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+ __be16 *bufp = buf;
+ __be16 *optr = buf;
+ u16 flags = L2TP_HDR_VER_2;
+ u32 tunnel_id = tunnel->peer_tunnel_id;
+ u32 session_id = session->peer_session_id;
+
+ if (session->send_seq)
+ flags |= L2TP_HDRFLAG_S;
+
+ /* Setup L2TP header. */
+ *bufp++ = htons(flags);
+ *bufp++ = htons(tunnel_id);
+ *bufp++ = htons(session_id);
+ if (session->send_seq) {
+ *bufp++ = htons(session->ns);
+ *bufp++ = 0;
+ session->ns++;
+ session->ns &= 0xffff;
+ l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
+ session->name, session->ns);
+ }
+
+ return bufp - optr;
+}
+
+static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+ char *bufp = buf;
+ char *optr = bufp;
+
+ /* Setup L2TP header. The header differs slightly for UDP and
+ * IP encapsulations. For UDP, there is 4 bytes of flags.
+ */
+ if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
+ u16 flags = L2TP_HDR_VER_3;
+ *((__be16 *) bufp) = htons(flags);
+ bufp += 2;
+ *((__be16 *) bufp) = 0;
+ bufp += 2;
+ }
+
+ *((__be32 *) bufp) = htonl(session->peer_session_id);
+ bufp += 4;
+ if (session->cookie_len) {
+ memcpy(bufp, &session->cookie[0], session->cookie_len);
+ bufp += session->cookie_len;
+ }
+ if (session->l2specific_len) {
+ if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
+ u32 l2h = 0;
+ if (session->send_seq) {
+ l2h = 0x40000000 | session->ns;
+ session->ns++;
+ session->ns &= 0xffffff;
+ l2tp_dbg(session, L2TP_MSG_SEQ,
+ "%s: updated ns to %u\n",
+ session->name, session->ns);
+ }
+
+ *((__be32 *) bufp) = htonl(l2h);
+ }
+ bufp += session->l2specific_len;
+ }
+ if (session->offset)
+ bufp += session->offset;
+
+ return bufp - optr;
+}
+
+static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
+ struct flowi *fl, size_t data_len)
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+ unsigned int len = skb->len;
+ int error;
+
+ /* Debug */
+ if (session->send_seq)
+ l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
+ session->name, data_len, session->ns - 1);
+ else
+ l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
+ session->name, data_len);
+
+ if (session->debug & L2TP_MSG_DATA) {
+ int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
+ unsigned char *datap = skb->data + uhlen;
+
+ pr_debug("%s: xmit\n", session->name);
+ print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
+ datap, min_t(size_t, 32, len - uhlen));
+ }
+
+ /* Queue the packet to IP for output */
+ skb->ignore_df = 1;
+#if IS_ENABLED(CONFIG_IPV6)
+ if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)
+ error = inet6_csk_xmit(tunnel->sock, skb, NULL);
+ else
+#endif
+ error = ip_queue_xmit(tunnel->sock, skb, fl);
+
+ /* Update stats */
+ if (error >= 0) {
+ atomic_long_inc(&tunnel->stats.tx_packets);
+ atomic_long_add(len, &tunnel->stats.tx_bytes);
+ atomic_long_inc(&session->stats.tx_packets);
+ atomic_long_add(len, &session->stats.tx_bytes);
+ } else {
+ atomic_long_inc(&tunnel->stats.tx_errors);
+ atomic_long_inc(&session->stats.tx_errors);
+ }
+
+ return 0;
+}
+
+/* If caller requires the skb to have a ppp header, the header must be
+ * inserted in the skb data before calling this function.
+ */
+int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
+{
+ int data_len = skb->len;
+ struct l2tp_tunnel *tunnel = session->tunnel;
+ struct sock *sk = tunnel->sock;
+ struct flowi *fl;
+ struct udphdr *uh;
+ struct inet_sock *inet;
+ int headroom;
+ int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
+ int udp_len;
+ int ret = NET_XMIT_SUCCESS;
+
+ /* Check that there's enough headroom in the skb to insert IP,
+ * UDP and L2TP headers. If not enough, expand it to
+ * make room. Adjust truesize.
+ */
+ headroom = NET_SKB_PAD + sizeof(struct iphdr) +
+ uhlen + hdr_len;
+ if (skb_cow_head(skb, headroom)) {
+ kfree_skb(skb);
+ return NET_XMIT_DROP;
+ }
+
+ /* Setup L2TP header */
+ session->build_header(session, __skb_push(skb, hdr_len));
+
+ /* Reset skb netfilter state */
+ memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+ IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
+ IPSKB_REROUTED);
+ nf_reset(skb);
+
+ bh_lock_sock(sk);
+ if (sock_owned_by_user(sk)) {
+ kfree_skb(skb);
+ ret = NET_XMIT_DROP;
+ goto out_unlock;
+ }
+
+ /* Get routing info from the tunnel socket */
+ skb_dst_drop(skb);
+ skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
+
+ inet = inet_sk(sk);
+ fl = &inet->cork.fl;
+ switch (tunnel->encap) {
+ case L2TP_ENCAPTYPE_UDP:
+ /* Setup UDP header */
+ __skb_push(skb, sizeof(*uh));
+ skb_reset_transport_header(skb);
+ uh = udp_hdr(skb);
+ uh->source = inet->inet_sport;
+ uh->dest = inet->inet_dport;
+ udp_len = uhlen + hdr_len + data_len;
+ uh->len = htons(udp_len);
+
+ /* Calculate UDP checksum if configured to do so */
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
+ udp6_set_csum(udp_get_no_check6_tx(sk),
+ skb, &inet6_sk(sk)->saddr,
+ &sk->sk_v6_daddr, udp_len);
+ else
+#endif
+ udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
+ inet->inet_daddr, udp_len);
+ break;
+
+ case L2TP_ENCAPTYPE_IP:
+ break;
+ }
+
+ l2tp_xmit_core(session, skb, fl, data_len);
+out_unlock:
+ bh_unlock_sock(sk);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
+
+/*****************************************************************************
+ * Tinnel and session create/destroy.
+ *****************************************************************************/
+
+/* Tunnel socket destruct hook.
+ * The tunnel context is deleted only when all session sockets have been
+ * closed.
+ */
+static void l2tp_tunnel_destruct(struct sock *sk)
+{
+ struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
+ struct l2tp_net *pn;
+
+ if (tunnel == NULL)
+ goto end;
+
+ l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
+
+
+ /* Disable udp encapsulation */
+ switch (tunnel->encap) {
+ case L2TP_ENCAPTYPE_UDP:
+ /* No longer an encapsulation socket. See net/ipv4/udp.c */
+ (udp_sk(sk))->encap_type = 0;
+ (udp_sk(sk))->encap_rcv = NULL;
+ (udp_sk(sk))->encap_destroy = NULL;
+ break;
+ case L2TP_ENCAPTYPE_IP:
+ break;
+ }
+
+ /* Remove hooks into tunnel socket */
+ sk->sk_destruct = tunnel->old_sk_destruct;
+ sk->sk_user_data = NULL;
+ tunnel->sock = NULL;
+
+ /* Remove the tunnel struct from the tunnel list */
+ pn = l2tp_pernet(tunnel->l2tp_net);
+ spin_lock_bh(&pn->l2tp_tunnel_list_lock);
+ list_del_rcu(&tunnel->list);
+ spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
+ atomic_dec(&l2tp_tunnel_count);
+
+ l2tp_tunnel_closeall(tunnel);
+ l2tp_tunnel_dec_refcount(tunnel);
+
+ /* Call the original destructor */
+ if (sk->sk_destruct)
+ (*sk->sk_destruct)(sk);
+end:
+ return;
+}
+
+/* When the tunnel is closed, all the attached sessions need to go too.
+ */
+void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
+{
+ int hash;
+ struct hlist_node *walk;
+ struct hlist_node *tmp;
+ struct l2tp_session *session;
+
+ BUG_ON(tunnel == NULL);
+
+ l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
+ tunnel->name);
+
+ write_lock_bh(&tunnel->hlist_lock);
+ for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
+again:
+ hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
+ session = hlist_entry(walk, struct l2tp_session, hlist);
+
+ l2tp_info(session, L2TP_MSG_CONTROL,
+ "%s: closing session\n", session->name);
+
+ hlist_del_init(&session->hlist);
+
+ if (session->ref != NULL)
+ (*session->ref)(session);
+
+ write_unlock_bh(&tunnel->hlist_lock);
+
+ __l2tp_session_unhash(session);
+ l2tp_session_queue_purge(session);
+
+ if (session->session_close != NULL)
+ (*session->session_close)(session);
+
+ if (session->deref != NULL)
+ (*session->deref)(session);
+
+ l2tp_session_dec_refcount(session);
+
+ write_lock_bh(&tunnel->hlist_lock);
+
+ /* Now restart from the beginning of this hash
+ * chain. We always remove a session from the
+ * list so we are guaranteed to make forward
+ * progress.
+ */
+ goto again;
+ }
+ }
+ write_unlock_bh(&tunnel->hlist_lock);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
+
+/* Tunnel socket destroy hook for UDP encapsulation */
+static void l2tp_udp_encap_destroy(struct sock *sk)
+{
+ struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
+ if (tunnel) {
+ l2tp_tunnel_closeall(tunnel);
+ sock_put(sk);
+ }
+}
+
+/* Really kill the tunnel.
+ * Come here only when all sessions have been cleared from the tunnel.
+ */
+static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
+{
+ BUG_ON(atomic_read(&tunnel->ref_count) != 0);
+ BUG_ON(tunnel->sock != NULL);
+ l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
+ kfree_rcu(tunnel, rcu);
+}
+
+/* Workqueue tunnel deletion function */
+static void l2tp_tunnel_del_work(struct work_struct *work)
+{
+ struct l2tp_tunnel *tunnel = NULL;
+ struct socket *sock = NULL;
+ struct sock *sk = NULL;
+
+ tunnel = container_of(work, struct l2tp_tunnel, del_work);
+ sk = l2tp_tunnel_sock_lookup(tunnel);
+ if (!sk)
+ return;
+
+ sock = sk->sk_socket;
+
+ /* If the tunnel socket was created by userspace, then go through the
+ * inet layer to shut the socket down, and let userspace close it.
+ * Otherwise, if we created the socket directly within the kernel, use
+ * the sk API to release it here.
+ * In either case the tunnel resources are freed in the socket
+ * destructor when the tunnel socket goes away.
+ */
+ if (tunnel->fd >= 0) {
+ if (sock)
+ inet_shutdown(sock, 2);
+ } else {
+ if (sock)
+ kernel_sock_shutdown(sock, SHUT_RDWR);
+ sk_release_kernel(sk);
+ }
+
+ l2tp_tunnel_sock_put(sk);
+}
+
+/* Create a socket for the tunnel, if one isn't set up by
+ * userspace. This is used for static tunnels where there is no
+ * managing L2TP daemon.
+ *
+ * Since we don't want these sockets to keep a namespace alive by
+ * themselves, we drop the socket's namespace refcount after creation.
+ * These sockets are freed when the namespace exits using the pernet
+ * exit hook.
+ */
+static int l2tp_tunnel_sock_create(struct net *net,
+ u32 tunnel_id,
+ u32 peer_tunnel_id,
+ struct l2tp_tunnel_cfg *cfg,
+ struct socket **sockp)
+{
+ int err = -EINVAL;
+ struct socket *sock = NULL;
+ struct udp_port_cfg udp_conf;
+
+ switch (cfg->encap) {
+ case L2TP_ENCAPTYPE_UDP:
+ memset(&udp_conf, 0, sizeof(udp_conf));
+
+#if IS_ENABLED(CONFIG_IPV6)
+ if (cfg->local_ip6 && cfg->peer_ip6) {
+ udp_conf.family = AF_INET6;
+ memcpy(&udp_conf.local_ip6, cfg->local_ip6,
+ sizeof(udp_conf.local_ip6));
+ memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
+ sizeof(udp_conf.peer_ip6));
+ udp_conf.use_udp6_tx_checksums =
+ cfg->udp6_zero_tx_checksums;
+ udp_conf.use_udp6_rx_checksums =
+ cfg->udp6_zero_rx_checksums;
+ } else
+#endif
+ {
+ udp_conf.family = AF_INET;
+ udp_conf.local_ip = cfg->local_ip;
+ udp_conf.peer_ip = cfg->peer_ip;
+ udp_conf.use_udp_checksums = cfg->use_udp_checksums;
+ }
+
+ udp_conf.local_udp_port = htons(cfg->local_udp_port);
+ udp_conf.peer_udp_port = htons(cfg->peer_udp_port);
+
+ err = udp_sock_create(net, &udp_conf, &sock);
+ if (err < 0)
+ goto out;
+
+ break;
+
+ case L2TP_ENCAPTYPE_IP:
+#if IS_ENABLED(CONFIG_IPV6)
+ if (cfg->local_ip6 && cfg->peer_ip6) {
+ struct sockaddr_l2tpip6 ip6_addr = {0};
+
+ err = sock_create_kern(AF_INET6, SOCK_DGRAM,
+ IPPROTO_L2TP, &sock);
+ if (err < 0)
+ goto out;
+
+ sk_change_net(sock->sk, net);
+
+ ip6_addr.l2tp_family = AF_INET6;
+ memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
+ sizeof(ip6_addr.l2tp_addr));
+ ip6_addr.l2tp_conn_id = tunnel_id;
+ err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
+ sizeof(ip6_addr));
+ if (err < 0)
+ goto out;
+
+ ip6_addr.l2tp_family = AF_INET6;
+ memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
+ sizeof(ip6_addr.l2tp_addr));
+ ip6_addr.l2tp_conn_id = peer_tunnel_id;
+ err = kernel_connect(sock,
+ (struct sockaddr *) &ip6_addr,
+ sizeof(ip6_addr), 0);
+ if (err < 0)
+ goto out;
+ } else
+#endif
+ {
+ struct sockaddr_l2tpip ip_addr = {0};
+
+ err = sock_create_kern(AF_INET, SOCK_DGRAM,
+ IPPROTO_L2TP, &sock);
+ if (err < 0)
+ goto out;
+
+ sk_change_net(sock->sk, net);
+
+ ip_addr.l2tp_family = AF_INET;
+ ip_addr.l2tp_addr = cfg->local_ip;
+ ip_addr.l2tp_conn_id = tunnel_id;
+ err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
+ sizeof(ip_addr));
+ if (err < 0)
+ goto out;
+
+ ip_addr.l2tp_family = AF_INET;
+ ip_addr.l2tp_addr = cfg->peer_ip;
+ ip_addr.l2tp_conn_id = peer_tunnel_id;
+ err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
+ sizeof(ip_addr), 0);
+ if (err < 0)
+ goto out;
+ }
+ break;
+
+ default:
+ goto out;
+ }
+
+out:
+ *sockp = sock;
+ if ((err < 0) && sock) {
+ kernel_sock_shutdown(sock, SHUT_RDWR);
+ sk_release_kernel(sock->sk);
+ *sockp = NULL;
+ }
+
+ return err;
+}
+
+static struct lock_class_key l2tp_socket_class;
+
+int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
+{
+ struct l2tp_tunnel *tunnel = NULL;
+ int err;
+ struct socket *sock = NULL;
+ struct sock *sk = NULL;
+ struct l2tp_net *pn;
+ enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
+
+ /* Get the tunnel socket from the fd, which was opened by
+ * the userspace L2TP daemon. If not specified, create a
+ * kernel socket.
+ */
+ if (fd < 0) {
+ err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
+ cfg, &sock);
+ if (err < 0)
+ goto err;
+ } else {
+ sock = sockfd_lookup(fd, &err);
+ if (!sock) {
+ pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
+ tunnel_id, fd, err);
+ err = -EBADF;
+ goto err;
+ }
+
+ /* Reject namespace mismatches */
+ if (!net_eq(sock_net(sock->sk), net)) {
+ pr_err("tunl %u: netns mismatch\n", tunnel_id);
+ err = -EINVAL;
+ goto err;
+ }
+ }
+
+ sk = sock->sk;
+
+ if (cfg != NULL)
+ encap = cfg->encap;
+
+ /* Quick sanity checks */
+ switch (encap) {
+ case L2TP_ENCAPTYPE_UDP:
+ err = -EPROTONOSUPPORT;
+ if (sk->sk_protocol != IPPROTO_UDP) {
+ pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
+ tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
+ goto err;
+ }
+ break;
+ case L2TP_ENCAPTYPE_IP:
+ err = -EPROTONOSUPPORT;
+ if (sk->sk_protocol != IPPROTO_L2TP) {
+ pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
+ tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
+ goto err;
+ }
+ break;
+ }
+
+ /* Check if this socket has already been prepped */
+ tunnel = l2tp_tunnel(sk);
+ if (tunnel != NULL) {
+ /* This socket has already been prepped */
+ err = -EBUSY;
+ goto err;
+ }
+
+ tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
+ if (tunnel == NULL) {
+ err = -ENOMEM;
+ goto err;
+ }
+
+ tunnel->version = version;
+ tunnel->tunnel_id = tunnel_id;
+ tunnel->peer_tunnel_id = peer_tunnel_id;
+ tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
+
+ tunnel->magic = L2TP_TUNNEL_MAGIC;
+ sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
+ rwlock_init(&tunnel->hlist_lock);
+
+ /* The net we belong to */
+ tunnel->l2tp_net = net;
+ pn = l2tp_pernet(net);
+
+ if (cfg != NULL)
+ tunnel->debug = cfg->debug;
+
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == PF_INET6) {
+ struct ipv6_pinfo *np = inet6_sk(sk);
+
+ if (ipv6_addr_v4mapped(&np->saddr) &&
+ ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
+ struct inet_sock *inet = inet_sk(sk);
+
+ tunnel->v4mapped = true;
+ inet->inet_saddr = np->saddr.s6_addr32[3];
+ inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];
+ inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];
+ } else {
+ tunnel->v4mapped = false;
+ }
+ }
+#endif
+
+ /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
+ tunnel->encap = encap;
+ if (encap == L2TP_ENCAPTYPE_UDP) {
+ struct udp_tunnel_sock_cfg udp_cfg;
+
+ udp_cfg.sk_user_data = tunnel;
+ udp_cfg.encap_type = UDP_ENCAP_L2TPINUDP;
+ udp_cfg.encap_rcv = l2tp_udp_encap_recv;
+ udp_cfg.encap_destroy = l2tp_udp_encap_destroy;
+
+ setup_udp_tunnel_sock(net, sock, &udp_cfg);
+ } else {
+ sk->sk_user_data = tunnel;
+ }
+
+ /* Hook on the tunnel socket destructor so that we can cleanup
+ * if the tunnel socket goes away.
+ */
+ tunnel->old_sk_destruct = sk->sk_destruct;
+ sk->sk_destruct = &l2tp_tunnel_destruct;
+ tunnel->sock = sk;
+ tunnel->fd = fd;
+ lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
+
+ sk->sk_allocation = GFP_ATOMIC;
+
+ /* Init delete workqueue struct */
+ INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
+
+ /* Add tunnel to our list */
+ INIT_LIST_HEAD(&tunnel->list);
+ atomic_inc(&l2tp_tunnel_count);
+
+ /* Bump the reference count. The tunnel context is deleted
+ * only when this drops to zero. Must be done before list insertion
+ */
+ l2tp_tunnel_inc_refcount(tunnel);
+ spin_lock_bh(&pn->l2tp_tunnel_list_lock);
+ list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
+ spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
+
+ err = 0;
+err:
+ if (tunnelp)
+ *tunnelp = tunnel;
+
+ /* If tunnel's socket was created by the kernel, it doesn't
+ * have a file.
+ */
+ if (sock && sock->file)
+ sockfd_put(sock);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
+
+/* This function is used by the netlink TUNNEL_DELETE command.
+ */
+int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
+{
+ l2tp_tunnel_closeall(tunnel);
+ return (false == queue_work(l2tp_wq, &tunnel->del_work));
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
+
+/* Really kill the session.
+ */
+void l2tp_session_free(struct l2tp_session *session)
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+
+ BUG_ON(atomic_read(&session->ref_count) != 0);
+
+ if (tunnel) {
+ BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+ if (session->session_id != 0)
+ atomic_dec(&l2tp_session_count);
+ sock_put(tunnel->sock);
+ session->tunnel = NULL;
+ l2tp_tunnel_dec_refcount(tunnel);
+ }
+
+ kfree(session);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_free);
+
+/* Remove an l2tp session from l2tp_core's hash lists.
+ * Provides a tidyup interface for pseudowire code which can't just route all
+ * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
+ * callback.
+ */
+void __l2tp_session_unhash(struct l2tp_session *session)
+{
+ struct l2tp_tunnel *tunnel = session->tunnel;
+
+ /* Remove the session from core hashes */
+ if (tunnel) {
+ /* Remove from the per-tunnel hash */
+ write_lock_bh(&tunnel->hlist_lock);
+ hlist_del_init(&session->hlist);
+ write_unlock_bh(&tunnel->hlist_lock);
+
+ /* For L2TPv3 we have a per-net hash: remove from there, too */
+ if (tunnel->version != L2TP_HDR_VER_2) {
+ struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
+ spin_lock_bh(&pn->l2tp_session_hlist_lock);
+ hlist_del_init_rcu(&session->global_hlist);
+ spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ synchronize_rcu();
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
+
+/* This function is used by the netlink SESSION_DELETE command and by
+ pseudowire modules.
+ */
+int l2tp_session_delete(struct l2tp_session *session)
+{
+ if (session->ref)
+ (*session->ref)(session);
+ __l2tp_session_unhash(session);
+ l2tp_session_queue_purge(session);
+ if (session->session_close != NULL)
+ (*session->session_close)(session);
+ if (session->deref)
+ (*session->deref)(session);
+ l2tp_session_dec_refcount(session);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_delete);
+
+/* We come here whenever a session's send_seq, cookie_len or
+ * l2specific_len parameters are set.
+ */
+void l2tp_session_set_header_len(struct l2tp_session *session, int version)
+{
+ if (version == L2TP_HDR_VER_2) {
+ session->hdr_len = 6;
+ if (session->send_seq)
+ session->hdr_len += 4;
+ } else {
+ session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
+ if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
+ session->hdr_len += 4;
+ }
+
+}
+EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
+
+struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
+{
+ struct l2tp_session *session;
+
+ session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
+ if (session != NULL) {
+ session->magic = L2TP_SESSION_MAGIC;
+ session->tunnel = tunnel;
+
+ session->session_id = session_id;
+ session->peer_session_id = peer_session_id;
+ session->nr = 0;
+ if (tunnel->version == L2TP_HDR_VER_2)
+ session->nr_max = 0xffff;
+ else
+ session->nr_max = 0xffffff;
+ session->nr_window_size = session->nr_max / 2;
+ session->nr_oos_count_max = 4;
+
+ /* Use NR of first received packet */
+ session->reorder_skip = 1;
+
+ sprintf(&session->name[0], "sess %u/%u",
+ tunnel->tunnel_id, session->session_id);
+
+ skb_queue_head_init(&session->reorder_q);
+
+ INIT_HLIST_NODE(&session->hlist);
+ INIT_HLIST_NODE(&session->global_hlist);
+
+ /* Inherit debug options from tunnel */
+ session->debug = tunnel->debug;
+
+ if (cfg) {
+ session->pwtype = cfg->pw_type;
+ session->debug = cfg->debug;
+ session->mtu = cfg->mtu;
+ session->mru = cfg->mru;
+ session->send_seq = cfg->send_seq;
+ session->recv_seq = cfg->recv_seq;
+ session->lns_mode = cfg->lns_mode;
+ session->reorder_timeout = cfg->reorder_timeout;
+ session->offset = cfg->offset;
+ session->l2specific_type = cfg->l2specific_type;
+ session->l2specific_len = cfg->l2specific_len;
+ session->cookie_len = cfg->cookie_len;
+ memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
+ session->peer_cookie_len = cfg->peer_cookie_len;
+ memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
+ }
+
+ if (tunnel->version == L2TP_HDR_VER_2)
+ session->build_header = l2tp_build_l2tpv2_header;
+ else
+ session->build_header = l2tp_build_l2tpv3_header;
+
+ l2tp_session_set_header_len(session, tunnel->version);
+
+ /* Bump the reference count. The session context is deleted
+ * only when this drops to zero.
+ */
+ l2tp_session_inc_refcount(session);
+ l2tp_tunnel_inc_refcount(tunnel);
+
+ /* Ensure tunnel socket isn't deleted */
+ sock_hold(tunnel->sock);
+
+ /* Add session to the tunnel's hash list */
+ write_lock_bh(&tunnel->hlist_lock);
+ hlist_add_head(&session->hlist,
+ l2tp_session_id_hash(tunnel, session_id));
+ write_unlock_bh(&tunnel->hlist_lock);
+
+ /* And to the global session list if L2TPv3 */
+ if (tunnel->version != L2TP_HDR_VER_2) {
+ struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
+
+ spin_lock_bh(&pn->l2tp_session_hlist_lock);
+ hlist_add_head_rcu(&session->global_hlist,
+ l2tp_session_id_hash_2(pn, session_id));
+ spin_unlock_bh(&pn->l2tp_session_hlist_lock);
+ }
+
+ /* Ignore management session in session count value */
+ if (session->session_id != 0)
+ atomic_inc(&l2tp_session_count);
+ }
+
+ return session;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_create);
+
+/*****************************************************************************
+ * Init and cleanup
+ *****************************************************************************/
+
+static __net_init int l2tp_init_net(struct net *net)
+{
+ struct l2tp_net *pn = net_generic(net, l2tp_net_id);
+ int hash;
+
+ INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
+ spin_lock_init(&pn->l2tp_tunnel_list_lock);
+
+ for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
+ INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
+
+ spin_lock_init(&pn->l2tp_session_hlist_lock);
+
+ return 0;
+}
+
+static __net_exit void l2tp_exit_net(struct net *net)
+{
+ struct l2tp_net *pn = l2tp_pernet(net);
+ struct l2tp_tunnel *tunnel = NULL;
+
+ rcu_read_lock_bh();
+ list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
+ (void)l2tp_tunnel_delete(tunnel);
+ }
+ rcu_read_unlock_bh();
+}
+
+static struct pernet_operations l2tp_net_ops = {
+ .init = l2tp_init_net,
+ .exit = l2tp_exit_net,
+ .id = &l2tp_net_id,
+ .size = sizeof(struct l2tp_net),
+};
+
+static int __init l2tp_init(void)
+{
+ int rc = 0;
+
+ rc = register_pernet_device(&l2tp_net_ops);
+ if (rc)
+ goto out;
+
+ l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0);
+ if (!l2tp_wq) {
+ pr_err("alloc_workqueue failed\n");
+ unregister_pernet_device(&l2tp_net_ops);
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
+
+out:
+ return rc;
+}
+
+static void __exit l2tp_exit(void)
+{
+ unregister_pernet_device(&l2tp_net_ops);
+ if (l2tp_wq) {
+ destroy_workqueue(l2tp_wq);
+ l2tp_wq = NULL;
+ }
+}
+
+module_init(l2tp_init);
+module_exit(l2tp_exit);
+
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("L2TP core");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(L2TP_DRV_VERSION);
+
Code Review / kvmfornfv.git / blobdiff