1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* L2TP internal definitions. 3 * 4 * Copyright (c) 2008,2009 Katalix Systems Ltd 5 */ 6 #include <linux/refcount.h> 7 8 #ifndef _L2TP_CORE_H_ 9 #define _L2TP_CORE_H_ 10 11 #include <net/dst.h> 12 #include <net/sock.h> 13 14 #ifdef CONFIG_XFRM 15 #include <net/xfrm.h> 16 #endif 17 18 /* Random numbers used for internal consistency checks of tunnel and session structures */ 19 #define L2TP_SESSION_MAGIC 0x0C04EB7D 20 21 struct sk_buff; 22 23 struct l2tp_stats { 24 atomic_long_t tx_packets; 25 atomic_long_t tx_bytes; 26 atomic_long_t tx_errors; 27 atomic_long_t rx_packets; 28 atomic_long_t rx_bytes; 29 atomic_long_t rx_seq_discards; 30 atomic_long_t rx_oos_packets; 31 atomic_long_t rx_errors; 32 atomic_long_t rx_cookie_discards; 33 atomic_long_t rx_invalid; 34 }; 35 36 struct l2tp_tunnel; 37 38 /* L2TP session configuration */ 39 struct l2tp_session_cfg { 40 enum l2tp_pwtype pw_type; 41 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ 42 unsigned int send_seq:1; /* send packets with sequence numbers? */ 43 unsigned int lns_mode:1; /* behave as LNS? 44 * LAC enables sequence numbers under LNS control. 45 */ 46 u16 l2specific_type; /* Layer 2 specific type */ 47 u8 cookie[8]; /* optional cookie */ 48 int cookie_len; /* 0, 4 or 8 bytes */ 49 u8 peer_cookie[8]; /* peer's cookie */ 50 int peer_cookie_len; /* 0, 4 or 8 bytes */ 51 int reorder_timeout; /* configured reorder timeout (in jiffies) */ 52 char *ifname; 53 }; 54 55 struct l2tp_session_coll_list { 56 spinlock_t lock; /* for access to list */ 57 struct list_head list; 58 refcount_t ref_count; 59 }; 60 61 /* Represents a session (pseudowire) instance. 62 * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics. 63 * Is linked into a per-tunnel session list and a per-net ("global") IDR tree. 64 */ 65 #define L2TP_SESSION_NAME_MAX 32 66 struct l2tp_session { 67 int magic; /* should be L2TP_SESSION_MAGIC */ 68 long dead; 69 struct rcu_head rcu; 70 71 struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */ 72 u32 session_id; 73 u32 peer_session_id; 74 u8 cookie[8]; 75 int cookie_len; 76 u8 peer_cookie[8]; 77 int peer_cookie_len; 78 u16 l2specific_type; 79 u16 hdr_len; 80 u32 nr; /* session NR state (receive) */ 81 u32 ns; /* session NR state (send) */ 82 struct sk_buff_head reorder_q; /* receive reorder queue */ 83 u32 nr_max; /* max NR. Depends on tunnel */ 84 u32 nr_window_size; /* NR window size */ 85 u32 nr_oos; /* NR of last OOS packet */ 86 int nr_oos_count; /* for OOS recovery */ 87 int nr_oos_count_max; 88 struct list_head list; /* per-tunnel list node */ 89 refcount_t ref_count; 90 struct hlist_node hlist; /* per-net session hlist */ 91 unsigned long hlist_key; /* key for session hlist */ 92 struct l2tp_session_coll_list *coll_list; /* session collision list */ 93 struct list_head clist; /* for coll_list */ 94 95 char name[L2TP_SESSION_NAME_MAX]; /* for logging */ 96 char ifname[IFNAMSIZ]; 97 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ 98 unsigned int send_seq:1; /* send packets with sequence numbers? */ 99 unsigned int lns_mode:1; /* behave as LNS? 100 * LAC enables sequence numbers under LNS control. 101 */ 102 int reorder_timeout; /* configured reorder timeout (in jiffies) */ 103 int reorder_skip; /* set if skip to next nr */ 104 enum l2tp_pwtype pwtype; 105 struct l2tp_stats stats; 106 struct work_struct del_work; 107 108 /* Session receive handler for data packets. 109 * Each pseudowire implementation should implement this callback in order to 110 * handle incoming packets. Packets are passed to the pseudowire handler after 111 * reordering, if data sequence numbers are enabled for the session. 112 */ 113 void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len); 114 115 /* Session close handler. 116 * Each pseudowire implementation may implement this callback in order to carry 117 * out pseudowire-specific shutdown actions. 118 * The callback is called by core after unlisting the session and purging its 119 * reorder queue. 120 */ 121 void (*session_close)(struct l2tp_session *session); 122 123 /* Session show handler. 124 * Pseudowire-specific implementation of debugfs session rendering. 125 * The callback is called by l2tp_debugfs.c after rendering core session 126 * information. 127 */ 128 void (*show)(struct seq_file *m, void *priv); 129 130 u8 priv[]; /* private data */ 131 }; 132 133 /* L2TP tunnel configuration */ 134 struct l2tp_tunnel_cfg { 135 enum l2tp_encap_type encap; 136 137 /* Used only for kernel-created sockets */ 138 struct in_addr local_ip; 139 struct in_addr peer_ip; 140 #if IS_ENABLED(CONFIG_IPV6) 141 struct in6_addr *local_ip6; 142 struct in6_addr *peer_ip6; 143 #endif 144 u16 local_udp_port; 145 u16 peer_udp_port; 146 unsigned int use_udp_checksums:1, 147 udp6_zero_tx_checksums:1, 148 udp6_zero_rx_checksums:1; 149 }; 150 151 /* Represents a tunnel instance. 152 * Tracks runtime state including IO statistics. 153 * Holds the tunnel socket (either passed from userspace or directly created by the kernel). 154 * Maintains a list of sessions belonging to the tunnel instance. 155 * Is linked into a per-net list of tunnels. 156 */ 157 #define L2TP_TUNNEL_NAME_MAX 20 158 struct l2tp_tunnel { 159 unsigned long dead; 160 161 struct rcu_head rcu; 162 spinlock_t list_lock; /* write-protection for session_list */ 163 bool acpt_newsess; /* indicates whether this tunnel accepts 164 * new sessions. Protected by list_lock. 165 */ 166 struct list_head session_list; /* list of sessions */ 167 u32 tunnel_id; 168 u32 peer_tunnel_id; 169 int version; /* 2=>L2TPv2, 3=>L2TPv3 */ 170 171 char name[L2TP_TUNNEL_NAME_MAX]; /* for logging */ 172 enum l2tp_encap_type encap; 173 struct l2tp_stats stats; 174 175 struct net *l2tp_net; /* the net we belong to */ 176 177 refcount_t ref_count; 178 struct sock *sock; /* parent socket */ 179 int fd; /* parent fd, if tunnel socket was created 180 * by userspace 181 */ 182 183 struct work_struct del_work; 184 }; 185 186 /* Pseudowire ops callbacks for use with the l2tp genetlink interface */ 187 struct l2tp_nl_cmd_ops { 188 /* The pseudowire session create callback is responsible for creating a session 189 * instance for a specific pseudowire type. 190 * It must call l2tp_session_create and l2tp_session_register to register the 191 * session instance, as well as carry out any pseudowire-specific initialisation. 192 * It must return >= 0 on success, or an appropriate negative errno value on failure. 193 */ 194 int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel, 195 u32 session_id, u32 peer_session_id, 196 struct l2tp_session_cfg *cfg); 197 198 /* The pseudowire session delete callback is responsible for initiating the deletion 199 * of a session instance. 200 * It must call l2tp_session_delete, as well as carry out any pseudowire-specific 201 * teardown actions. 202 */ 203 void (*session_delete)(struct l2tp_session *session); 204 }; 205 206 static inline void *l2tp_session_priv(struct l2tp_session *session) 207 { 208 return &session->priv[0]; 209 } 210 211 /* Tunnel and session refcounts */ 212 void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel); 213 void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel); 214 void l2tp_session_inc_refcount(struct l2tp_session *session); 215 void l2tp_session_dec_refcount(struct l2tp_session *session); 216 217 /* Tunnel and session lookup. 218 * These functions take a reference on the instances they return, so 219 * the caller must ensure that the reference is dropped appropriately. 220 */ 221 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id); 222 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth); 223 224 struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id); 225 struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id); 226 struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver, 227 u32 tunnel_id, u32 session_id); 228 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth); 229 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 230 const char *ifname); 231 232 /* Tunnel and session lifetime management. 233 * Creation of a new instance is a two-step process: create, then register. 234 * Destruction is triggered using the *_delete functions, and completes asynchronously. 235 */ 236 int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, 237 u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, 238 struct l2tp_tunnel **tunnelp); 239 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 240 struct l2tp_tunnel_cfg *cfg); 241 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel); 242 243 struct l2tp_session *l2tp_session_create(int priv_size, 244 struct l2tp_tunnel *tunnel, 245 u32 session_id, u32 peer_session_id, 246 struct l2tp_session_cfg *cfg); 247 int l2tp_session_register(struct l2tp_session *session, 248 struct l2tp_tunnel *tunnel); 249 void l2tp_session_delete(struct l2tp_session *session); 250 251 /* Receive path helpers. If data sequencing is enabled for the session these 252 * functions handle queuing and reordering prior to passing packets to the 253 * pseudowire code to be passed to userspace. 254 */ 255 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 256 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 257 int length); 258 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb); 259 260 /* Transmit path helpers for sending packets over the tunnel socket. */ 261 void l2tp_session_set_header_len(struct l2tp_session *session, int version, 262 enum l2tp_encap_type encap); 263 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb); 264 265 /* Pseudowire management. 266 * Pseudowires should register with l2tp core on module init, and unregister 267 * on module exit. 268 */ 269 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops); 270 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type); 271 272 /* IOCTL helper for IP encap modules. */ 273 int l2tp_ioctl(struct sock *sk, int cmd, int *karg); 274 275 struct l2tp_tunnel *l2tp_sk_to_tunnel(const struct sock *sk); 276 277 static inline int l2tp_get_l2specific_len(struct l2tp_session *session) 278 { 279 switch (session->l2specific_type) { 280 case L2TP_L2SPECTYPE_DEFAULT: 281 return 4; 282 case L2TP_L2SPECTYPE_NONE: 283 default: 284 return 0; 285 } 286 } 287 288 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel) 289 { 290 struct dst_entry *dst; 291 u32 mtu; 292 293 dst = sk_dst_get(tunnel->sock); 294 if (!dst) 295 return 0; 296 297 mtu = dst_mtu(dst); 298 dst_release(dst); 299 300 return mtu; 301 } 302 303 #ifdef CONFIG_XFRM 304 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) 305 { 306 struct sock *sk = tunnel->sock; 307 308 return sk && (rcu_access_pointer(sk->sk_policy[0]) || 309 rcu_access_pointer(sk->sk_policy[1])); 310 } 311 #else 312 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) 313 { 314 return false; 315 } 316 #endif 317 318 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb, 319 unsigned char **ptr, unsigned char **optr) 320 { 321 int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session); 322 323 if (opt_len > 0) { 324 int off = *ptr - *optr; 325 326 if (!pskb_may_pull(skb, off + opt_len)) 327 return -1; 328 329 if (skb->data != *optr) { 330 *optr = skb->data; 331 *ptr = skb->data + off; 332 } 333 } 334 335 return 0; 336 } 337 338 #define MODULE_ALIAS_L2TP_PWTYPE(type) \ 339 MODULE_ALIAS("net-l2tp-type-" __stringify(type)) 340 341 #endif /* _L2TP_CORE_H_ */ 342