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_TUNNEL_MAGIC 0x42114DDA 20 #define L2TP_SESSION_MAGIC 0x0C04EB7D 21 22 /* Per tunnel session hash table size */ 23 #define L2TP_HASH_BITS 4 24 #define L2TP_HASH_SIZE BIT(L2TP_HASH_BITS) 25 26 /* System-wide session hash table size */ 27 #define L2TP_HASH_BITS_2 8 28 #define L2TP_HASH_SIZE_2 BIT(L2TP_HASH_BITS_2) 29 30 struct sk_buff; 31 32 struct l2tp_stats { 33 atomic_long_t tx_packets; 34 atomic_long_t tx_bytes; 35 atomic_long_t tx_errors; 36 atomic_long_t rx_packets; 37 atomic_long_t rx_bytes; 38 atomic_long_t rx_seq_discards; 39 atomic_long_t rx_oos_packets; 40 atomic_long_t rx_errors; 41 atomic_long_t rx_cookie_discards; 42 atomic_long_t rx_invalid; 43 }; 44 45 struct l2tp_tunnel; 46 47 /* L2TP session configuration */ 48 struct l2tp_session_cfg { 49 enum l2tp_pwtype pw_type; 50 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ 51 unsigned int send_seq:1; /* send packets with sequence numbers? */ 52 unsigned int lns_mode:1; /* behave as LNS? 53 * LAC enables sequence numbers under LNS control. 54 */ 55 u16 l2specific_type; /* Layer 2 specific type */ 56 u8 cookie[8]; /* optional cookie */ 57 int cookie_len; /* 0, 4 or 8 bytes */ 58 u8 peer_cookie[8]; /* peer's cookie */ 59 int peer_cookie_len; /* 0, 4 or 8 bytes */ 60 int reorder_timeout; /* configured reorder timeout (in jiffies) */ 61 char *ifname; 62 }; 63 64 /* Represents a session (pseudowire) instance. 65 * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics. 66 * Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into 67 * an additional per-net ("global") hashlist. 68 */ 69 #define L2TP_SESSION_NAME_MAX 32 70 struct l2tp_session { 71 int magic; /* should be L2TP_SESSION_MAGIC */ 72 long dead; 73 74 struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */ 75 u32 session_id; 76 u32 peer_session_id; 77 u8 cookie[8]; 78 int cookie_len; 79 u8 peer_cookie[8]; 80 int peer_cookie_len; 81 u16 l2specific_type; 82 u16 hdr_len; 83 u32 nr; /* session NR state (receive) */ 84 u32 ns; /* session NR state (send) */ 85 struct sk_buff_head reorder_q; /* receive reorder queue */ 86 u32 nr_max; /* max NR. Depends on tunnel */ 87 u32 nr_window_size; /* NR window size */ 88 u32 nr_oos; /* NR of last OOS packet */ 89 int nr_oos_count; /* for OOS recovery */ 90 int nr_oos_count_max; 91 struct hlist_node hlist; /* hash list node */ 92 refcount_t ref_count; 93 94 char name[L2TP_SESSION_NAME_MAX]; /* for logging */ 95 char ifname[IFNAMSIZ]; 96 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ 97 unsigned int send_seq:1; /* send packets with sequence numbers? */ 98 unsigned int lns_mode:1; /* behave as LNS? 99 * LAC enables sequence numbers under LNS control. 100 */ 101 int reorder_timeout; /* configured reorder timeout (in jiffies) */ 102 int reorder_skip; /* set if skip to next nr */ 103 enum l2tp_pwtype pwtype; 104 struct l2tp_stats stats; 105 struct hlist_node global_hlist; /* global hash list node */ 106 107 /* Session receive handler for data packets. 108 * Each pseudowire implementation should implement this callback in order to 109 * handle incoming packets. Packets are passed to the pseudowire handler after 110 * reordering, if data sequence numbers are enabled for the session. 111 */ 112 void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len); 113 114 /* Session close handler. 115 * Each pseudowire implementation may implement this callback in order to carry 116 * out pseudowire-specific shutdown actions. 117 * The callback is called by core after unhashing the session and purging its 118 * reorder queue. 119 */ 120 void (*session_close)(struct l2tp_session *session); 121 122 /* Session show handler. 123 * Pseudowire-specific implementation of debugfs session rendering. 124 * The callback is called by l2tp_debugfs.c after rendering core session 125 * information. 126 */ 127 void (*show)(struct seq_file *m, void *priv); 128 129 u8 priv[]; /* private data */ 130 }; 131 132 /* L2TP tunnel configuration */ 133 struct l2tp_tunnel_cfg { 134 enum l2tp_encap_type encap; 135 136 /* Used only for kernel-created sockets */ 137 struct in_addr local_ip; 138 struct in_addr peer_ip; 139 #if IS_ENABLED(CONFIG_IPV6) 140 struct in6_addr *local_ip6; 141 struct in6_addr *peer_ip6; 142 #endif 143 u16 local_udp_port; 144 u16 peer_udp_port; 145 unsigned int use_udp_checksums:1, 146 udp6_zero_tx_checksums:1, 147 udp6_zero_rx_checksums:1; 148 }; 149 150 /* Represents a tunnel instance. 151 * Tracks runtime state including IO statistics. 152 * Holds the tunnel socket (either passed from userspace or directly created by the kernel). 153 * Maintains a hashlist of sessions belonging to the tunnel instance. 154 * Is linked into a per-net list of tunnels. 155 */ 156 #define L2TP_TUNNEL_NAME_MAX 20 157 struct l2tp_tunnel { 158 int magic; /* Should be L2TP_TUNNEL_MAGIC */ 159 160 unsigned long dead; 161 162 struct rcu_head rcu; 163 spinlock_t hlist_lock; /* write-protection for session_hlist */ 164 bool acpt_newsess; /* indicates whether this tunnel accepts 165 * new sessions. Protected by hlist_lock. 166 */ 167 struct hlist_head session_hlist[L2TP_HASH_SIZE]; 168 /* hashed list of sessions, hashed by id */ 169 u32 tunnel_id; 170 u32 peer_tunnel_id; 171 int version; /* 2=>L2TPv2, 3=>L2TPv3 */ 172 173 char name[L2TP_TUNNEL_NAME_MAX]; /* for logging */ 174 enum l2tp_encap_type encap; 175 struct l2tp_stats stats; 176 177 struct list_head list; /* list node on per-namespace list of tunnels */ 178 struct net *l2tp_net; /* the net we belong to */ 179 180 refcount_t ref_count; 181 void (*old_sk_destruct)(struct sock *sk); 182 struct sock *sock; /* parent socket */ 183 int fd; /* parent fd, if tunnel socket was created 184 * by userspace 185 */ 186 187 struct work_struct del_work; 188 }; 189 190 /* Pseudowire ops callbacks for use with the l2tp genetlink interface */ 191 struct l2tp_nl_cmd_ops { 192 /* The pseudowire session create callback is responsible for creating a session 193 * instance for a specific pseudowire type. 194 * It must call l2tp_session_create and l2tp_session_register to register the 195 * session instance, as well as carry out any pseudowire-specific initialisation. 196 * It must return >= 0 on success, or an appropriate negative errno value on failure. 197 */ 198 int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel, 199 u32 session_id, u32 peer_session_id, 200 struct l2tp_session_cfg *cfg); 201 202 /* The pseudowire session delete callback is responsible for initiating the deletion 203 * of a session instance. 204 * It must call l2tp_session_delete, as well as carry out any pseudowire-specific 205 * teardown actions. 206 */ 207 void (*session_delete)(struct l2tp_session *session); 208 }; 209 210 static inline void *l2tp_session_priv(struct l2tp_session *session) 211 { 212 return &session->priv[0]; 213 } 214 215 /* Tunnel and session refcounts */ 216 void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel); 217 void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel); 218 void l2tp_session_inc_refcount(struct l2tp_session *session); 219 void l2tp_session_dec_refcount(struct l2tp_session *session); 220 221 /* Tunnel and session lookup. 222 * These functions take a reference on the instances they return, so 223 * the caller must ensure that the reference is dropped appropriately. 224 */ 225 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id); 226 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth); 227 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 228 u32 session_id); 229 230 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id); 231 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth); 232 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 233 const char *ifname); 234 235 /* Tunnel and session lifetime management. 236 * Creation of a new instance is a two-step process: create, then register. 237 * Destruction is triggered using the *_delete functions, and completes asynchronously. 238 */ 239 int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, 240 u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, 241 struct l2tp_tunnel **tunnelp); 242 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 243 struct l2tp_tunnel_cfg *cfg); 244 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel); 245 246 struct l2tp_session *l2tp_session_create(int priv_size, 247 struct l2tp_tunnel *tunnel, 248 u32 session_id, u32 peer_session_id, 249 struct l2tp_session_cfg *cfg); 250 int l2tp_session_register(struct l2tp_session *session, 251 struct l2tp_tunnel *tunnel); 252 void l2tp_session_delete(struct l2tp_session *session); 253 254 /* Receive path helpers. If data sequencing is enabled for the session these 255 * functions handle queuing and reordering prior to passing packets to the 256 * pseudowire code to be passed to userspace. 257 */ 258 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 259 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 260 int length); 261 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb); 262 263 /* Transmit path helpers for sending packets over the tunnel socket. */ 264 void l2tp_session_set_header_len(struct l2tp_session *session, int version); 265 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb); 266 267 /* Pseudowire management. 268 * Pseudowires should register with l2tp core on module init, and unregister 269 * on module exit. 270 */ 271 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops); 272 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type); 273 274 /* IOCTL helper for IP encap modules. */ 275 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg); 276 277 /* Extract the tunnel structure from a socket's sk_user_data pointer, 278 * validating the tunnel magic feather. 279 */ 280 struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk); 281 282 static inline int l2tp_get_l2specific_len(struct l2tp_session *session) 283 { 284 switch (session->l2specific_type) { 285 case L2TP_L2SPECTYPE_DEFAULT: 286 return 4; 287 case L2TP_L2SPECTYPE_NONE: 288 default: 289 return 0; 290 } 291 } 292 293 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel) 294 { 295 struct dst_entry *dst; 296 u32 mtu; 297 298 dst = sk_dst_get(tunnel->sock); 299 if (!dst) 300 return 0; 301 302 mtu = dst_mtu(dst); 303 dst_release(dst); 304 305 return mtu; 306 } 307 308 #ifdef CONFIG_XFRM 309 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) 310 { 311 struct sock *sk = tunnel->sock; 312 313 return sk && (rcu_access_pointer(sk->sk_policy[0]) || 314 rcu_access_pointer(sk->sk_policy[1])); 315 } 316 #else 317 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) 318 { 319 return false; 320 } 321 #endif 322 323 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb, 324 unsigned char **ptr, unsigned char **optr) 325 { 326 int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session); 327 328 if (opt_len > 0) { 329 int off = *ptr - *optr; 330 331 if (!pskb_may_pull(skb, off + opt_len)) 332 return -1; 333 334 if (skb->data != *optr) { 335 *optr = skb->data; 336 *ptr = skb->data + off; 337 } 338 } 339 340 return 0; 341 } 342 343 #define MODULE_ALIAS_L2TP_PWTYPE(type) \ 344 MODULE_ALIAS("net-l2tp-type-" __stringify(type)) 345 346 #endif /* _L2TP_CORE_H_ */ 347