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 }; 43 44 struct l2tp_tunnel; 45 46 /* L2TP session configuration */ 47 struct l2tp_session_cfg { 48 enum l2tp_pwtype pw_type; 49 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ 50 unsigned int send_seq:1; /* send packets with sequence numbers? */ 51 unsigned int lns_mode:1; /* behave as LNS? 52 * LAC enables sequence numbers under LNS control. 53 */ 54 int debug; /* bitmask of debug message categories */ 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 struct l2tp_session { 70 int magic; /* should be L2TP_SESSION_MAGIC */ 71 long dead; 72 73 struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */ 74 u32 session_id; 75 u32 peer_session_id; 76 u8 cookie[8]; 77 int cookie_len; 78 u8 peer_cookie[8]; 79 int peer_cookie_len; 80 u16 l2specific_type; 81 u16 hdr_len; 82 u32 nr; /* session NR state (receive) */ 83 u32 ns; /* session NR state (send) */ 84 struct sk_buff_head reorder_q; /* receive reorder queue */ 85 u32 nr_max; /* max NR. Depends on tunnel */ 86 u32 nr_window_size; /* NR window size */ 87 u32 nr_oos; /* NR of last OOS packet */ 88 int nr_oos_count; /* for OOS recovery */ 89 int nr_oos_count_max; 90 struct hlist_node hlist; /* hash list node */ 91 refcount_t ref_count; 92 93 char name[32]; /* for logging */ 94 char ifname[IFNAMSIZ]; 95 unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */ 96 unsigned int send_seq:1; /* send packets with sequence numbers? */ 97 unsigned int lns_mode:1; /* behave as LNS? 98 * LAC enables sequence numbers under LNS control. 99 */ 100 int debug; /* bitmask of debug message categories */ 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 int debug; /* bitmask of debug message categories */ 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 hashlist of sessions belonging to the tunnel instance. 155 * Is linked into a per-net list of tunnels. 156 */ 157 struct l2tp_tunnel { 158 int magic; /* Should be L2TP_TUNNEL_MAGIC */ 159 160 unsigned long dead; 161 162 struct rcu_head rcu; 163 rwlock_t hlist_lock; /* protect 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[20]; /* for logging */ 174 int debug; /* bitmask of debug message categories */ 175 enum l2tp_encap_type encap; 176 struct l2tp_stats stats; 177 178 struct list_head list; /* list node on per-namespace list of tunnels */ 179 struct net *l2tp_net; /* the net we belong to */ 180 181 refcount_t ref_count; 182 void (*old_sk_destruct)(struct sock *sk); 183 struct sock *sock; /* parent socket */ 184 int fd; /* parent fd, if tunnel socket was created 185 * by userspace 186 */ 187 188 struct work_struct del_work; 189 }; 190 191 /* Pseudowire ops callbacks for use with the l2tp genetlink interface */ 192 struct l2tp_nl_cmd_ops { 193 /* The pseudowire session create callback is responsible for creating a session 194 * instance for a specific pseudowire type. 195 * It must call l2tp_session_create and l2tp_session_register to register the 196 * session instance, as well as carry out any pseudowire-specific initialisation. 197 * It must return >= 0 on success, or an appropriate negative errno value on failure. 198 */ 199 int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel, 200 u32 session_id, u32 peer_session_id, 201 struct l2tp_session_cfg *cfg); 202 203 /* The pseudowire session delete callback is responsible for initiating the deletion 204 * of a session instance. 205 * It must call l2tp_session_delete, as well as carry out any pseudowire-specific 206 * teardown actions. 207 */ 208 void (*session_delete)(struct l2tp_session *session); 209 }; 210 211 static inline void *l2tp_session_priv(struct l2tp_session *session) 212 { 213 return &session->priv[0]; 214 } 215 216 /* Tunnel and session refcounts */ 217 void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel); 218 void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel); 219 void l2tp_session_inc_refcount(struct l2tp_session *session); 220 void l2tp_session_dec_refcount(struct l2tp_session *session); 221 222 /* Tunnel and session lookup. 223 * These functions take a reference on the instances they return, so 224 * the caller must ensure that the reference is dropped appropriately. 225 */ 226 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id); 227 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth); 228 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 229 u32 session_id); 230 231 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id); 232 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth); 233 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 234 const char *ifname); 235 236 /* Tunnel and session lifetime management. 237 * Creation of a new instance is a two-step process: create, then register. 238 * Destruction is triggered using the *_delete functions, and completes asynchronously. 239 */ 240 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, 241 u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, 242 struct l2tp_tunnel **tunnelp); 243 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 244 struct l2tp_tunnel_cfg *cfg); 245 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel); 246 247 struct l2tp_session *l2tp_session_create(int priv_size, 248 struct l2tp_tunnel *tunnel, 249 u32 session_id, u32 peer_session_id, 250 struct l2tp_session_cfg *cfg); 251 int l2tp_session_register(struct l2tp_session *session, 252 struct l2tp_tunnel *tunnel); 253 void l2tp_session_delete(struct l2tp_session *session); 254 255 /* Receive path helpers. If data sequencing is enabled for the session these 256 * functions handle queuing and reordering prior to passing packets to the 257 * pseudowire code to be passed to userspace. 258 */ 259 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 260 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 261 int length); 262 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb); 263 264 /* Transmit path helpers for sending packets over the tunnel socket. */ 265 void l2tp_session_set_header_len(struct l2tp_session *session, int version); 266 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, 267 int hdr_len); 268 269 /* Pseudowire management. 270 * Pseudowires should register with l2tp core on module init, and unregister 271 * on module exit. 272 */ 273 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops); 274 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type); 275 276 /* IOCTL helper for IP encap modules. */ 277 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg); 278 279 static inline int l2tp_get_l2specific_len(struct l2tp_session *session) 280 { 281 switch (session->l2specific_type) { 282 case L2TP_L2SPECTYPE_DEFAULT: 283 return 4; 284 case L2TP_L2SPECTYPE_NONE: 285 default: 286 return 0; 287 } 288 } 289 290 static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel) 291 { 292 struct dst_entry *dst; 293 u32 mtu; 294 295 dst = sk_dst_get(tunnel->sock); 296 if (!dst) 297 return 0; 298 299 mtu = dst_mtu(dst); 300 dst_release(dst); 301 302 return mtu; 303 } 304 305 #ifdef CONFIG_XFRM 306 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) 307 { 308 struct sock *sk = tunnel->sock; 309 310 return sk && (rcu_access_pointer(sk->sk_policy[0]) || 311 rcu_access_pointer(sk->sk_policy[1])); 312 } 313 #else 314 static inline bool l2tp_tunnel_uses_xfrm(const struct l2tp_tunnel *tunnel) 315 { 316 return false; 317 } 318 #endif 319 320 static inline int l2tp_v3_ensure_opt_in_linear(struct l2tp_session *session, struct sk_buff *skb, 321 unsigned char **ptr, unsigned char **optr) 322 { 323 int opt_len = session->peer_cookie_len + l2tp_get_l2specific_len(session); 324 325 if (opt_len > 0) { 326 int off = *ptr - *optr; 327 328 if (!pskb_may_pull(skb, off + opt_len)) 329 return -1; 330 331 if (skb->data != *optr) { 332 *optr = skb->data; 333 *ptr = skb->data + off; 334 } 335 } 336 337 return 0; 338 } 339 340 #define l2tp_printk(ptr, type, func, fmt, ...) \ 341 do { \ 342 if (((ptr)->debug) & (type)) \ 343 func(fmt, ##__VA_ARGS__); \ 344 } while (0) 345 346 #define l2tp_warn(ptr, type, fmt, ...) \ 347 l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__) 348 #define l2tp_info(ptr, type, fmt, ...) \ 349 l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__) 350 #define l2tp_dbg(ptr, type, fmt, ...) \ 351 l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__) 352 353 #define MODULE_ALIAS_L2TP_PWTYPE(type) \ 354 MODULE_ALIAS("net-l2tp-type-" __stringify(type)) 355 356 #endif /* _L2TP_CORE_H_ */ 357