/* * 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 * James Chapman (jchapman@katalix.com) * Contributors: * Michal Ostrowski * Arnaldo Carvalho de Melo * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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_session_set_header_len(struct l2tp_session *session, int version); 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 inline int l2tp_verify_udp_checksum(struct sock *sk, struct sk_buff *skb) { struct udphdr *uh = udp_hdr(skb); u16 ulen = ntohs(uh->len); __wsum psum; if (sk->sk_no_check || skb_csum_unnecessary(skb)) return 0; #if IS_ENABLED(CONFIG_IPV6) if (sk->sk_family == PF_INET6 && !l2tp_tunnel(sk)->v4mapped) { if (!uh->check) { LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n"); return 1; } if ((skb->ip_summed == CHECKSUM_COMPLETE) && !csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr, ulen, IPPROTO_UDP, skb->csum)) { skb->ip_summed = CHECKSUM_UNNECESSARY; return 0; } skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr, skb->len, IPPROTO_UDP, 0)); } else #endif { struct inet_sock *inet; if (!uh->check) return 0; inet = inet_sk(sk); psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen, IPPROTO_UDP, 0); if ((skb->ip_summed == CHECKSUM_COMPLETE) && !csum_fold(csum_add(psum, skb->csum))) return 0; skb->csum = psum; } return __skb_checksum_complete(skb); } 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; if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb)) goto discard_bad_csum; /* 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; discard_bad_csum: LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name); UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0); atomic_long_inc(&tunnel->stats.rx_errors); kfree_skb(skb); 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->local_df = 1; #if IS_ENABLED(CONFIG_IPV6) if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped) error = inet6_csk_xmit(skb, NULL); else #endif error = ip_queue_xmit(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 IS_ENABLED(CONFIG_IPV6) static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb, int udp_len) { struct ipv6_pinfo *np = inet6_sk(sk); struct udphdr *uh = udp_hdr(skb); if (!skb_dst(skb) || !skb_dst(skb)->dev || !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) { __wsum csum = skb_checksum(skb, 0, udp_len, 0); skb->ip_summed = CHECKSUM_UNNECESSARY; uh->check = csum_ipv6_magic(&np->saddr, &sk->sk_v6_daddr, udp_len, IPPROTO_UDP, csum); if (uh->check == 0) uh->check = CSUM_MANGLED_0; } else { skb->ip_summed = CHECKSUM_PARTIAL; skb->csum_start = skb_transport_header(skb) - skb->head; skb->csum_offset = offsetof(struct udphdr, check); uh->check = ~csum_ipv6_magic(&np->saddr, &sk->sk_v6_daddr, udp_len, IPPROTO_UDP, 0); } } #endif /* 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; __wsum csum; 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); uh->check = 0; /* Calculate UDP checksum if configured to do so */ #if IS_ENABLED(CONFIG_IPV6) if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) l2tp_xmit_ipv6_csum(sk, skb, udp_len); else #endif if (sk->sk_no_check == UDP_CSUM_NOXMIT) skb->ip_summed = CHECKSUM_NONE; else if ((skb_dst(skb) && skb_dst(skb)->dev) && (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) { skb->ip_summed = CHECKSUM_COMPLETE; csum = skb_checksum(skb, 0, udp_len, 0); uh->check = csum_tcpudp_magic(inet->inet_saddr, inet->inet_daddr, udp_len, IPPROTO_UDP, csum); if (uh->check == 0) uh->check = CSUM_MANGLED_0; } else { skb->ip_summed = CHECKSUM_PARTIAL; skb->csum_start = skb_transport_header(skb) - skb->head; skb->csum_offset = offsetof(struct udphdr, check); uh->check = ~csum_tcpudp_magic(inet->inet_saddr, inet->inet_daddr, udp_len, IPPROTO_UDP, 0); } 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 sockaddr_in udp_addr = {0}; struct sockaddr_l2tpip ip_addr = {0}; #if IS_ENABLED(CONFIG_IPV6) struct sockaddr_in6 udp6_addr = {0}; struct sockaddr_l2tpip6 ip6_addr = {0}; #endif switch (cfg->encap) { case L2TP_ENCAPTYPE_UDP: #if IS_ENABLED(CONFIG_IPV6) if (cfg->local_ip6 && cfg->peer_ip6) { err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock); if (err < 0) goto out; sk_change_net(sock->sk, net); udp6_addr.sin6_family = AF_INET6; memcpy(&udp6_addr.sin6_addr, cfg->local_ip6, sizeof(udp6_addr.sin6_addr)); udp6_addr.sin6_port = htons(cfg->local_udp_port); err = kernel_bind(sock, (struct sockaddr *) &udp6_addr, sizeof(udp6_addr)); if (err < 0) goto out; udp6_addr.sin6_family = AF_INET6; memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6, sizeof(udp6_addr.sin6_addr)); udp6_addr.sin6_port = htons(cfg->peer_udp_port); err = kernel_connect(sock, (struct sockaddr *) &udp6_addr, sizeof(udp6_addr), 0); if (err < 0) goto out; } else #endif { err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock); if (err < 0) goto out; sk_change_net(sock->sk, net); udp_addr.sin_family = AF_INET; udp_addr.sin_addr = cfg->local_ip; udp_addr.sin_port = htons(cfg->local_udp_port); err = kernel_bind(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr)); if (err < 0) goto out; udp_addr.sin_family = AF_INET; udp_addr.sin_addr = cfg->peer_ip; udp_addr.sin_port = htons(cfg->peer_udp_port); err = kernel_connect(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr), 0); if (err < 0) goto out; } if (!cfg->use_udp_checksums) sock->sk->sk_no_check = UDP_CSUM_NOXMIT; break; case L2TP_ENCAPTYPE_IP: #if IS_ENABLED(CONFIG_IPV6) if (cfg->local_ip6 && cfg->peer_ip6) { 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 { 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) { /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP; udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv; udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy; #if IS_ENABLED(CONFIG_IPV6) if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) udpv6_encap_enable(); else #endif udp_encap_enable(); } 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. */ static 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; } } 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_NON_REENTRANT | WQ_UNBOUND, 0); if (!l2tp_wq) { pr_err("alloc_workqueue failed\n"); 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 "); MODULE_DESCRIPTION("L2TP core"); MODULE_LICENSE("GPL"); MODULE_VERSION(L2TP_DRV_VERSION);