diff options
Diffstat (limited to 'net/l2tp/l2tp_core.c')
| -rw-r--r-- | net/l2tp/l2tp_core.c | 1723 |
1 files changed, 1723 insertions, 0 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c new file mode 100644 index 000000000..8d21ff25f --- /dev/null +++ b/net/l2tp/l2tp_core.c @@ -0,0 +1,1723 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* 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) + */ + +#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" +#include "trace.h" + +#define CREATE_TRACE_POINTS +#include "trace.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_MAX 14 + +/* 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 struct workqueue_struct *l2tp_wq; + +/* per-net private data for this module */ +static unsigned int l2tp_net_id; +struct l2tp_net { + /* Lock for write access to l2tp_tunnel_idr */ + spinlock_t l2tp_tunnel_idr_lock; + struct idr l2tp_tunnel_idr; + struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; + /* Lock for write access to l2tp_session_hlist */ + spinlock_t l2tp_session_hlist_lock; +}; + +#if IS_ENABLED(CONFIG_IPV6) +static bool l2tp_sk_is_v6(struct sock *sk) +{ + return sk->sk_family == PF_INET6 && + !ipv6_addr_v4mapped(&sk->sk_v6_daddr); +} +#endif + +static inline struct l2tp_net *l2tp_pernet(const struct net *net) +{ + return net_generic(net, l2tp_net_id); +} + +/* 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)]; +} + +/* 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)]; +} + +static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) +{ + trace_free_tunnel(tunnel); + sock_put(tunnel->sock); + /* the tunnel is freed in the socket destructor */ +} + +static void l2tp_session_free(struct l2tp_session *session) +{ + trace_free_session(session); + if (session->tunnel) + l2tp_tunnel_dec_refcount(session->tunnel); + kfree(session); +} + +struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk) +{ + struct l2tp_tunnel *tunnel = sk->sk_user_data; + + if (tunnel) + if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) + return NULL; + + return tunnel; +} +EXPORT_SYMBOL_GPL(l2tp_sk_to_tunnel); + +void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel) +{ + refcount_inc(&tunnel->ref_count); +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount); + +void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel) +{ + if (refcount_dec_and_test(&tunnel->ref_count)) + l2tp_tunnel_free(tunnel); +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount); + +void l2tp_session_inc_refcount(struct l2tp_session *session) +{ + refcount_inc(&session->ref_count); +} +EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount); + +void l2tp_session_dec_refcount(struct l2tp_session *session) +{ + if (refcount_dec_and_test(&session->ref_count)) + l2tp_session_free(session); +} +EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount); + +/* Lookup a tunnel. A new reference is held on the returned tunnel. */ +struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) +{ + const struct l2tp_net *pn = l2tp_pernet(net); + struct l2tp_tunnel *tunnel; + + rcu_read_lock_bh(); + tunnel = idr_find(&pn->l2tp_tunnel_idr, tunnel_id); + if (tunnel && refcount_inc_not_zero(&tunnel->ref_count)) { + rcu_read_unlock_bh(); + return tunnel; + } + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_get); + +struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) +{ + struct l2tp_net *pn = l2tp_pernet(net); + unsigned long tunnel_id, tmp; + struct l2tp_tunnel *tunnel; + int count = 0; + + rcu_read_lock_bh(); + idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { + if (tunnel && ++count > nth && + refcount_inc_not_zero(&tunnel->ref_count)) { + rcu_read_unlock_bh(); + return tunnel; + } + } + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); + +struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, + u32 session_id) +{ + struct hlist_head *session_list; + struct l2tp_session *session; + + session_list = l2tp_session_id_hash(tunnel, session_id); + + rcu_read_lock_bh(); + hlist_for_each_entry_rcu(session, session_list, hlist) + if (session->session_id == session_id) { + l2tp_session_inc_refcount(session); + rcu_read_unlock_bh(); + + return session; + } + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); + +struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) +{ + struct hlist_head *session_list; + struct l2tp_session *session; + + session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id); + + rcu_read_lock_bh(); + hlist_for_each_entry_rcu(session, session_list, global_hlist) + if (session->session_id == session_id) { + l2tp_session_inc_refcount(session); + rcu_read_unlock_bh(); + + return session; + } + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_session_get); + +struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) +{ + int hash; + struct l2tp_session *session; + int count = 0; + + rcu_read_lock_bh(); + for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { + hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { + if (++count > nth) { + l2tp_session_inc_refcount(session); + rcu_read_unlock_bh(); + return session; + } + } + } + + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_session_get_nth); + +/* Lookup a session by interface name. + * This is very inefficient but is only used by management interfaces. + */ +struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, + const 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)) { + l2tp_session_inc_refcount(session); + rcu_read_unlock_bh(); + + return session; + } + } + } + + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); + +int l2tp_session_register(struct l2tp_session *session, + struct l2tp_tunnel *tunnel) +{ + struct l2tp_session *session_walk; + struct hlist_head *g_head; + struct hlist_head *head; + struct l2tp_net *pn; + int err; + + head = l2tp_session_id_hash(tunnel, session->session_id); + + spin_lock_bh(&tunnel->hlist_lock); + if (!tunnel->acpt_newsess) { + err = -ENODEV; + goto err_tlock; + } + + hlist_for_each_entry(session_walk, head, hlist) + if (session_walk->session_id == session->session_id) { + err = -EEXIST; + goto err_tlock; + } + + if (tunnel->version == L2TP_HDR_VER_3) { + pn = l2tp_pernet(tunnel->l2tp_net); + g_head = l2tp_session_id_hash_2(pn, session->session_id); + + spin_lock_bh(&pn->l2tp_session_hlist_lock); + + /* IP encap expects session IDs to be globally unique, while + * UDP encap doesn't. + */ + hlist_for_each_entry(session_walk, g_head, global_hlist) + if (session_walk->session_id == session->session_id && + (session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP || + tunnel->encap == L2TP_ENCAPTYPE_IP)) { + err = -EEXIST; + goto err_tlock_pnlock; + } + + l2tp_tunnel_inc_refcount(tunnel); + hlist_add_head_rcu(&session->global_hlist, g_head); + + spin_unlock_bh(&pn->l2tp_session_hlist_lock); + } else { + l2tp_tunnel_inc_refcount(tunnel); + } + + hlist_add_head_rcu(&session->hlist, head); + spin_unlock_bh(&tunnel->hlist_lock); + + trace_register_session(session); + + return 0; + +err_tlock_pnlock: + spin_unlock_bh(&pn->l2tp_session_hlist_lock); +err_tlock: + spin_unlock_bh(&tunnel->hlist_lock); + + return err; +} +EXPORT_SYMBOL_GPL(l2tp_session_register); + +/***************************************************************************** + * 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); + 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; + trace_session_seqnum_update(session); + } + + /* call private receive handler */ + if (session->recv_skb) + (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); + else + kfree_skb(skb); +} + +/* 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) { + struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb); + + /* If the packet has been pending on the queue for too long, discard it */ + if (time_after(jiffies, cb->expires)) { + atomic_long_inc(&session->stats.rx_seq_discards); + atomic_long_inc(&session->stats.rx_errors); + trace_session_pkt_expired(session, cb->ns); + session->reorder_skip = 1; + __skb_unlink(skb, &session->reorder_q); + kfree_skb(skb); + continue; + } + + if (cb->has_seq) { + if (session->reorder_skip) { + session->reorder_skip = 0; + session->nr = cb->ns; + trace_session_seqnum_reset(session); + } + if (cb->ns != session->nr) + 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) +{ + struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb); + + if (!l2tp_seq_check_rx_window(session, cb->ns)) { + /* Packet sequence number is outside allowed window. + * Discard it. + */ + trace_session_pkt_outside_rx_window(session, cb->ns); + 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 (cb->ns == session->nr) { + skb_queue_tail(&session->reorder_q, skb); + } else { + u32 nr_oos = cb->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; + } + if (!session->reorder_skip) { + atomic_long_inc(&session->stats.rx_seq_discards); + trace_session_pkt_oos(session, cb->ns); + 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 and sublayer format 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) +{ + struct l2tp_tunnel *tunnel = session->tunnel; + int offset; + + /* Parse and check optional cookie */ + if (session->peer_cookie_len > 0) { + if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { + pr_debug_ratelimited("%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. + */ + L2TP_SKB_CB(skb)->has_seq = 0; + if (tunnel->version == L2TP_HDR_VER_2) { + if (hdrflags & L2TP_HDRFLAG_S) { + /* Store L2TP info in the skb */ + L2TP_SKB_CB(skb)->ns = ntohs(*(__be16 *)ptr); + L2TP_SKB_CB(skb)->has_seq = 1; + ptr += 2; + /* Skip past nr in the header */ + ptr += 2; + + } + } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { + u32 l2h = ntohl(*(__be32 *)ptr); + + if (l2h & 0x40000000) { + /* Store L2TP info in the skb */ + L2TP_SKB_CB(skb)->ns = l2h & 0x00ffffff; + L2TP_SKB_CB(skb)->has_seq = 1; + } + ptr += 4; + } + + if (L2TP_SKB_CB(skb)->has_seq) { + /* Received a packet with sequence numbers. If we're the LAC, + * check if we sre sending sequence numbers and if not, + * configure it so. + */ + if (!session->lns_mode && !session->send_seq) { + trace_session_seqnum_lns_enable(session); + 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) { + pr_debug_ratelimited("%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) { + trace_session_seqnum_lns_disable(session); + session->send_seq = 0; + l2tp_session_set_header_len(session, tunnel->version); + } else if (session->send_seq) { + pr_debug_ratelimited("%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 defined only for L2TPv2 and is + * indicated by an optional 16-bit value in the header. + */ + 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; + } + } + + offset = ptr - optr; + if (!pskb_may_pull(skb, offset)) + goto discard; + + __skb_pull(skb, offset); + + /* 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); + + return; + +discard: + atomic_long_inc(&session->stats.rx_errors); + kfree_skb(skb); +} +EXPORT_SYMBOL_GPL(l2tp_recv_common); + +/* Drop skbs from the session's reorder_q + */ +static void l2tp_session_queue_purge(struct l2tp_session *session) +{ + struct sk_buff *skb = NULL; + + while ((skb = skb_dequeue(&session->reorder_q))) { + atomic_long_inc(&session->stats.rx_errors); + kfree_skb(skb); + } +} + +/* 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) +{ + struct l2tp_session *session = NULL; + unsigned char *ptr, *optr; + u16 hdrflags; + u32 tunnel_id, session_id; + u16 version; + int length; + + /* UDP has verified checksum */ + + /* UDP always verifies the packet length. */ + __skb_pull(skb, sizeof(struct udphdr)); + + /* Short packet? */ + if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) { + pr_debug_ratelimited("%s: recv short packet (len=%d)\n", + tunnel->name, skb->len); + goto invalid; + } + + /* Point to L2TP header */ + optr = skb->data; + ptr = skb->data; + + /* Get L2TP header flags */ + hdrflags = ntohs(*(__be16 *)ptr); + + /* Check protocol version */ + version = hdrflags & L2TP_HDR_VER_MASK; + if (version != tunnel->version) { + pr_debug_ratelimited("%s: recv protocol version mismatch: got %d expected %d\n", + tunnel->name, version, tunnel->version); + goto invalid; + } + + /* Get length of L2TP packet */ + length = skb->len; + + /* If type is control packet, it is handled by userspace. */ + if (hdrflags & L2TP_HDRFLAG_T) + goto pass; + + /* 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_tunnel_get_session(tunnel, session_id); + if (!session || !session->recv_skb) { + if (session) + l2tp_session_dec_refcount(session); + + /* Not found? Pass to userspace to deal with */ + pr_debug_ratelimited("%s: no session found (%u/%u). Passing up.\n", + tunnel->name, tunnel_id, session_id); + goto pass; + } + + if (tunnel->version == L2TP_HDR_VER_3 && + l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) { + l2tp_session_dec_refcount(session); + goto invalid; + } + + l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); + l2tp_session_dec_refcount(session); + + return 0; + +invalid: + atomic_long_inc(&tunnel->stats.rx_invalid); + +pass: + /* 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; + + /* Note that this is called from the encap_rcv hook inside an + * RCU-protected region, but without the socket being locked. + * Hence we use rcu_dereference_sk_user_data to access the + * tunnel data structure rather the usual l2tp_sk_to_tunnel + * accessor function. + */ + tunnel = rcu_dereference_sk_user_data(sk); + if (!tunnel) + goto pass_up; + if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) + goto pass_up; + + if (l2tp_udp_recv_core(tunnel, skb)) + goto pass_up; + + return 0; + +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; + trace_session_seqnum_update(session); + } + + 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_type == L2TP_L2SPECTYPE_DEFAULT) { + u32 l2h = 0; + + if (session->send_seq) { + l2h = 0x40000000 | session->ns; + session->ns++; + session->ns &= 0xffffff; + trace_session_seqnum_update(session); + } + + *((__be32 *)bufp) = htonl(l2h); + bufp += 4; + } + + return bufp - optr; +} + +/* Queue the packet to IP for output: tunnel socket lock must be held */ +static int l2tp_xmit_queue(struct l2tp_tunnel *tunnel, struct sk_buff *skb, struct flowi *fl) +{ + int err; + + skb->ignore_df = 1; + skb_dst_drop(skb); +#if IS_ENABLED(CONFIG_IPV6) + if (l2tp_sk_is_v6(tunnel->sock)) + err = inet6_csk_xmit(tunnel->sock, skb, NULL); + else +#endif + err = ip_queue_xmit(tunnel->sock, skb, fl); + + return err >= 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; +} + +static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, unsigned int *len) +{ + struct l2tp_tunnel *tunnel = session->tunnel; + unsigned int data_len = skb->len; + struct sock *sk = tunnel->sock; + int headroom, uhlen, udp_len; + int ret = NET_XMIT_SUCCESS; + struct inet_sock *inet; + struct udphdr *uh; + + /* 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. + */ + uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(*uh) : 0; + headroom = NET_SKB_PAD + sizeof(struct iphdr) + uhlen + session->hdr_len; + if (skb_cow_head(skb, headroom)) { + kfree_skb(skb); + return NET_XMIT_DROP; + } + + /* Setup L2TP header */ + if (tunnel->version == L2TP_HDR_VER_2) + l2tp_build_l2tpv2_header(session, __skb_push(skb, session->hdr_len)); + else + l2tp_build_l2tpv3_header(session, __skb_push(skb, session->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_ct(skb); + + bh_lock_sock_nested(sk); + if (sock_owned_by_user(sk)) { + kfree_skb(skb); + ret = NET_XMIT_DROP; + goto out_unlock; + } + + /* The user-space may change the connection status for the user-space + * provided socket at run time: we must check it under the socket lock + */ + if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { + kfree_skb(skb); + ret = NET_XMIT_DROP; + goto out_unlock; + } + + /* Report transmitted length before we add encap header, which keeps + * statistics consistent for both UDP and IP encap tx/rx paths. + */ + *len = skb->len; + + inet = inet_sk(sk); + 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 + session->hdr_len + data_len; + uh->len = htons(udp_len); + + /* Calculate UDP checksum if configured to do so */ +#if IS_ENABLED(CONFIG_IPV6) + if (l2tp_sk_is_v6(sk)) + 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; + } + + ret = l2tp_xmit_queue(tunnel, skb, &inet->cork.fl); + +out_unlock: + bh_unlock_sock(sk); + + return ret; +} + +/* 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) +{ + unsigned int len = 0; + int ret; + + ret = l2tp_xmit_core(session, skb, &len); + if (ret == NET_XMIT_SUCCESS) { + atomic_long_inc(&session->tunnel->stats.tx_packets); + atomic_long_add(len, &session->tunnel->stats.tx_bytes); + atomic_long_inc(&session->stats.tx_packets); + atomic_long_add(len, &session->stats.tx_bytes); + } else { + atomic_long_inc(&session->tunnel->stats.tx_errors); + atomic_long_inc(&session->stats.tx_errors); + } + 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_sk_to_tunnel(sk); + + if (!tunnel) + goto end; + + /* Disable udp encapsulation */ + switch (tunnel->encap) { + case L2TP_ENCAPTYPE_UDP: + /* No longer an encapsulation socket. See net/ipv4/udp.c */ + WRITE_ONCE(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 */ + write_lock_bh(&sk->sk_callback_lock); + sk->sk_destruct = tunnel->old_sk_destruct; + sk->sk_user_data = NULL; + write_unlock_bh(&sk->sk_callback_lock); + + /* Call the original destructor */ + if (sk->sk_destruct) + (*sk->sk_destruct)(sk); + + kfree_rcu(tunnel, rcu); +end: + return; +} + +/* Remove an l2tp session from l2tp_core's hash lists. */ +static 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 */ + spin_lock_bh(&tunnel->hlist_lock); + hlist_del_init_rcu(&session->hlist); + spin_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(); + } +} + +/* When the tunnel is closed, all the attached sessions need to go too. + */ +static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) +{ + struct l2tp_session *session; + int hash; + + spin_lock_bh(&tunnel->hlist_lock); + tunnel->acpt_newsess = false; + for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { +again: + hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { + hlist_del_init_rcu(&session->hlist); + + spin_unlock_bh(&tunnel->hlist_lock); + l2tp_session_delete(session); + spin_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; + } + } + spin_unlock_bh(&tunnel->hlist_lock); +} + +/* Tunnel socket destroy hook for UDP encapsulation */ +static void l2tp_udp_encap_destroy(struct sock *sk) +{ + struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); + + if (tunnel) + l2tp_tunnel_delete(tunnel); +} + +static void l2tp_tunnel_remove(struct net *net, struct l2tp_tunnel *tunnel) +{ + struct l2tp_net *pn = l2tp_pernet(net); + + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + idr_remove(&pn->l2tp_tunnel_idr, tunnel->tunnel_id); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); +} + +/* Workqueue tunnel deletion function */ +static void l2tp_tunnel_del_work(struct work_struct *work) +{ + struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, + del_work); + struct sock *sk = tunnel->sock; + struct socket *sock = sk->sk_socket; + + l2tp_tunnel_closeall(tunnel); + + /* If the tunnel socket was created within the kernel, use + * the sk API to release it here. + */ + if (tunnel->fd < 0) { + if (sock) { + kernel_sock_shutdown(sock, SHUT_RDWR); + sock_release(sock); + } + } + + l2tp_tunnel_remove(tunnel->l2tp_net, tunnel); + /* drop initial ref */ + l2tp_tunnel_dec_refcount(tunnel); + + /* drop workqueue ref */ + l2tp_tunnel_dec_refcount(tunnel); +} + +/* 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(net, AF_INET6, SOCK_DGRAM, + IPPROTO_L2TP, &sock); + if (err < 0) + goto out; + + 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(net, AF_INET, SOCK_DGRAM, + IPPROTO_L2TP, &sock); + if (err < 0) + goto out; + + 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); + sock_release(sock); + *sockp = NULL; + } + + return err; +} + +int l2tp_tunnel_create(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; + enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; + + if (cfg) + encap = cfg->encap; + + tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL); + if (!tunnel) { + err = -ENOMEM; + goto err; + } + + tunnel->version = version; + tunnel->tunnel_id = tunnel_id; + tunnel->peer_tunnel_id = peer_tunnel_id; + + tunnel->magic = L2TP_TUNNEL_MAGIC; + sprintf(&tunnel->name[0], "tunl %u", tunnel_id); + spin_lock_init(&tunnel->hlist_lock); + tunnel->acpt_newsess = true; + + tunnel->encap = encap; + + refcount_set(&tunnel->ref_count, 1); + tunnel->fd = fd; + + /* Init delete workqueue struct */ + INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); + + INIT_LIST_HEAD(&tunnel->list); + + err = 0; +err: + if (tunnelp) + *tunnelp = tunnel; + + return err; +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_create); + +static int l2tp_validate_socket(const struct sock *sk, const struct net *net, + enum l2tp_encap_type encap) +{ + if (!net_eq(sock_net(sk), net)) + return -EINVAL; + + if (sk->sk_type != SOCK_DGRAM) + return -EPROTONOSUPPORT; + + if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6) + return -EPROTONOSUPPORT; + + if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || + (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) + return -EPROTONOSUPPORT; + + if (sk->sk_user_data) + return -EBUSY; + + return 0; +} + +int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, + struct l2tp_tunnel_cfg *cfg) +{ + struct l2tp_net *pn = l2tp_pernet(net); + u32 tunnel_id = tunnel->tunnel_id; + struct socket *sock; + struct sock *sk; + int ret; + + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + ret = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, + GFP_ATOMIC); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); + if (ret) + return ret == -ENOSPC ? -EEXIST : ret; + + if (tunnel->fd < 0) { + ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, + tunnel->peer_tunnel_id, cfg, + &sock); + if (ret < 0) + goto err; + } else { + sock = sockfd_lookup(tunnel->fd, &ret); + if (!sock) + goto err; + } + + sk = sock->sk; + lock_sock(sk); + write_lock_bh(&sk->sk_callback_lock); + ret = l2tp_validate_socket(sk, net, tunnel->encap); + if (ret < 0) + goto err_inval_sock; + rcu_assign_sk_user_data(sk, tunnel); + write_unlock_bh(&sk->sk_callback_lock); + + if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { + struct udp_tunnel_sock_cfg udp_cfg = { + .sk_user_data = tunnel, + .encap_type = UDP_ENCAP_L2TPINUDP, + .encap_rcv = l2tp_udp_encap_recv, + .encap_destroy = l2tp_udp_encap_destroy, + }; + + setup_udp_tunnel_sock(net, sock, &udp_cfg); + } + + tunnel->old_sk_destruct = sk->sk_destruct; + sk->sk_destruct = &l2tp_tunnel_destruct; + sk->sk_allocation = GFP_ATOMIC; + release_sock(sk); + + sock_hold(sk); + tunnel->sock = sk; + tunnel->l2tp_net = net; + + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); + + trace_register_tunnel(tunnel); + + if (tunnel->fd >= 0) + sockfd_put(sock); + + return 0; + +err_inval_sock: + write_unlock_bh(&sk->sk_callback_lock); + release_sock(sk); + + if (tunnel->fd < 0) + sock_release(sock); + else + sockfd_put(sock); +err: + l2tp_tunnel_remove(net, tunnel); + return ret; +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_register); + +/* This function is used by the netlink TUNNEL_DELETE command. + */ +void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) +{ + if (!test_and_set_bit(0, &tunnel->dead)) { + trace_delete_tunnel(tunnel); + l2tp_tunnel_inc_refcount(tunnel); + queue_work(l2tp_wq, &tunnel->del_work); + } +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); + +void l2tp_session_delete(struct l2tp_session *session) +{ + if (test_and_set_bit(0, &session->dead)) + return; + + trace_delete_session(session); + l2tp_session_unhash(session); + l2tp_session_queue_purge(session); + if (session->session_close) + (*session->session_close)(session); + + l2tp_session_dec_refcount(session); +} +EXPORT_SYMBOL_GPL(l2tp_session_delete); + +/* We come here whenever a session's send_seq, cookie_len or + * l2specific_type 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->hdr_len += l2tp_get_l2specific_len(session); + 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(*session) + priv_size, GFP_KERNEL); + if (session) { + 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); + + if (cfg) { + session->pwtype = cfg->pw_type; + 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->l2specific_type = cfg->l2specific_type; + 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); + } + + l2tp_session_set_header_len(session, tunnel->version); + + refcount_set(&session->ref_count, 1); + + return session; + } + + return ERR_PTR(-ENOMEM); +} +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; + + idr_init(&pn->l2tp_tunnel_idr); + spin_lock_init(&pn->l2tp_tunnel_idr_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; + unsigned long tunnel_id, tmp; + int hash; + + rcu_read_lock_bh(); + idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { + if (tunnel) + l2tp_tunnel_delete(tunnel); + } + rcu_read_unlock_bh(); + + if (l2tp_wq) + flush_workqueue(l2tp_wq); + rcu_barrier(); + + for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) + WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); + idr_destroy(&pn->l2tp_tunnel_idr); +} + +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); |