1 /* 2 * NET Generic infrastructure for Network protocols. 3 * 4 * Definitions for request_sock 5 * 6 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br> 7 * 8 * From code originally in include/net/tcp.h 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 */ 15 #ifndef _REQUEST_SOCK_H 16 #define _REQUEST_SOCK_H 17 18 #include <linux/slab.h> 19 #include <linux/spinlock.h> 20 #include <linux/types.h> 21 #include <linux/bug.h> 22 23 #include <net/sock.h> 24 25 struct request_sock; 26 struct sk_buff; 27 struct dst_entry; 28 struct proto; 29 30 struct request_sock_ops { 31 int family; 32 int obj_size; 33 struct kmem_cache *slab; 34 char *slab_name; 35 int (*rtx_syn_ack)(struct sock *sk, 36 struct request_sock *req); 37 void (*send_ack)(struct sock *sk, struct sk_buff *skb, 38 struct request_sock *req); 39 void (*send_reset)(struct sock *sk, 40 struct sk_buff *skb); 41 void (*destructor)(struct request_sock *req); 42 void (*syn_ack_timeout)(const struct request_sock *req); 43 }; 44 45 int inet_rtx_syn_ack(struct sock *parent, struct request_sock *req); 46 47 /* struct request_sock - mini sock to represent a connection request 48 */ 49 struct request_sock { 50 struct sock_common __req_common; 51 #define rsk_refcnt __req_common.skc_refcnt 52 #define rsk_hash __req_common.skc_hash 53 54 struct request_sock *dl_next; 55 struct sock *rsk_listener; 56 u16 mss; 57 u8 num_retrans; /* number of retransmits */ 58 u8 cookie_ts:1; /* syncookie: encode tcpopts in timestamp */ 59 u8 num_timeout:7; /* number of timeouts */ 60 /* The following two fields can be easily recomputed I think -AK */ 61 u32 window_clamp; /* window clamp at creation time */ 62 u32 rcv_wnd; /* rcv_wnd offered first time */ 63 u32 ts_recent; 64 struct timer_list rsk_timer; 65 const struct request_sock_ops *rsk_ops; 66 struct sock *sk; 67 u32 secid; 68 u32 peer_secid; 69 }; 70 71 static inline struct request_sock * 72 reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener) 73 { 74 struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC); 75 76 if (req) { 77 req->rsk_ops = ops; 78 sock_hold(sk_listener); 79 req->rsk_listener = sk_listener; 80 81 /* Following is temporary. It is coupled with debugging 82 * helpers in reqsk_put() & reqsk_free() 83 */ 84 atomic_set(&req->rsk_refcnt, 0); 85 } 86 return req; 87 } 88 89 static inline struct request_sock *inet_reqsk(struct sock *sk) 90 { 91 return (struct request_sock *)sk; 92 } 93 94 static inline struct sock *req_to_sk(struct request_sock *req) 95 { 96 return (struct sock *)req; 97 } 98 99 static inline void reqsk_free(struct request_sock *req) 100 { 101 /* temporary debugging */ 102 WARN_ON_ONCE(atomic_read(&req->rsk_refcnt) != 0); 103 104 req->rsk_ops->destructor(req); 105 if (req->rsk_listener) 106 sock_put(req->rsk_listener); 107 kmem_cache_free(req->rsk_ops->slab, req); 108 } 109 110 static inline void reqsk_put(struct request_sock *req) 111 { 112 if (atomic_dec_and_test(&req->rsk_refcnt)) 113 reqsk_free(req); 114 } 115 116 extern int sysctl_max_syn_backlog; 117 118 /** struct listen_sock - listen state 119 * 120 * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs 121 */ 122 struct listen_sock { 123 int qlen_inc; /* protected by listener lock */ 124 int young_inc;/* protected by listener lock */ 125 126 /* following fields can be updated by timer */ 127 atomic_t qlen_dec; /* qlen = qlen_inc - qlen_dec */ 128 atomic_t young_dec; 129 130 u8 max_qlen_log ____cacheline_aligned_in_smp; 131 u8 synflood_warned; 132 /* 2 bytes hole, try to use */ 133 u32 hash_rnd; 134 u32 nr_table_entries; 135 struct request_sock *syn_table[0]; 136 }; 137 138 /* 139 * For a TCP Fast Open listener - 140 * lock - protects the access to all the reqsk, which is co-owned by 141 * the listener and the child socket. 142 * qlen - pending TFO requests (still in TCP_SYN_RECV). 143 * max_qlen - max TFO reqs allowed before TFO is disabled. 144 * 145 * XXX (TFO) - ideally these fields can be made as part of "listen_sock" 146 * structure above. But there is some implementation difficulty due to 147 * listen_sock being part of request_sock_queue hence will be freed when 148 * a listener is stopped. But TFO related fields may continue to be 149 * accessed even after a listener is closed, until its sk_refcnt drops 150 * to 0 implying no more outstanding TFO reqs. One solution is to keep 151 * listen_opt around until sk_refcnt drops to 0. But there is some other 152 * complexity that needs to be resolved. E.g., a listener can be disabled 153 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later. 154 */ 155 struct fastopen_queue { 156 struct request_sock *rskq_rst_head; /* Keep track of past TFO */ 157 struct request_sock *rskq_rst_tail; /* requests that caused RST. 158 * This is part of the defense 159 * against spoofing attack. 160 */ 161 spinlock_t lock; 162 int qlen; /* # of pending (TCP_SYN_RECV) reqs */ 163 int max_qlen; /* != 0 iff TFO is currently enabled */ 164 }; 165 166 /** struct request_sock_queue - queue of request_socks 167 * 168 * @rskq_accept_head - FIFO head of established children 169 * @rskq_accept_tail - FIFO tail of established children 170 * @rskq_defer_accept - User waits for some data after accept() 171 * @syn_wait_lock - serializer 172 * 173 * %syn_wait_lock is necessary only to avoid proc interface having to grab the main 174 * lock sock while browsing the listening hash (otherwise it's deadlock prone). 175 * 176 */ 177 struct request_sock_queue { 178 struct request_sock *rskq_accept_head; 179 struct request_sock *rskq_accept_tail; 180 u8 rskq_defer_accept; 181 struct listen_sock *listen_opt; 182 struct fastopen_queue *fastopenq; /* This is non-NULL iff TFO has been 183 * enabled on this listener. Check 184 * max_qlen != 0 in fastopen_queue 185 * to determine if TFO is enabled 186 * right at this moment. 187 */ 188 189 /* temporary alignment, our goal is to get rid of this lock */ 190 spinlock_t syn_wait_lock ____cacheline_aligned_in_smp; 191 }; 192 193 int reqsk_queue_alloc(struct request_sock_queue *queue, 194 unsigned int nr_table_entries); 195 196 void __reqsk_queue_destroy(struct request_sock_queue *queue); 197 void reqsk_queue_destroy(struct request_sock_queue *queue); 198 void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req, 199 bool reset); 200 201 static inline struct request_sock * 202 reqsk_queue_yank_acceptq(struct request_sock_queue *queue) 203 { 204 struct request_sock *req = queue->rskq_accept_head; 205 206 queue->rskq_accept_head = NULL; 207 return req; 208 } 209 210 static inline int reqsk_queue_empty(struct request_sock_queue *queue) 211 { 212 return queue->rskq_accept_head == NULL; 213 } 214 215 static inline void reqsk_queue_add(struct request_sock_queue *queue, 216 struct request_sock *req, 217 struct sock *parent, 218 struct sock *child) 219 { 220 req->sk = child; 221 sk_acceptq_added(parent); 222 223 if (queue->rskq_accept_head == NULL) 224 queue->rskq_accept_head = req; 225 else 226 queue->rskq_accept_tail->dl_next = req; 227 228 queue->rskq_accept_tail = req; 229 req->dl_next = NULL; 230 } 231 232 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue) 233 { 234 struct request_sock *req = queue->rskq_accept_head; 235 236 WARN_ON(req == NULL); 237 238 queue->rskq_accept_head = req->dl_next; 239 if (queue->rskq_accept_head == NULL) 240 queue->rskq_accept_tail = NULL; 241 242 return req; 243 } 244 245 static inline void reqsk_queue_removed(struct request_sock_queue *queue, 246 const struct request_sock *req) 247 { 248 struct listen_sock *lopt = queue->listen_opt; 249 250 if (req->num_timeout == 0) 251 atomic_inc(&lopt->young_dec); 252 atomic_inc(&lopt->qlen_dec); 253 } 254 255 static inline void reqsk_queue_added(struct request_sock_queue *queue) 256 { 257 struct listen_sock *lopt = queue->listen_opt; 258 259 lopt->young_inc++; 260 lopt->qlen_inc++; 261 } 262 263 static inline int listen_sock_qlen(const struct listen_sock *lopt) 264 { 265 return lopt->qlen_inc - atomic_read(&lopt->qlen_dec); 266 } 267 268 static inline int listen_sock_young(const struct listen_sock *lopt) 269 { 270 return lopt->young_inc - atomic_read(&lopt->young_dec); 271 } 272 273 static inline int reqsk_queue_len(const struct request_sock_queue *queue) 274 { 275 const struct listen_sock *lopt = queue->listen_opt; 276 277 return lopt ? listen_sock_qlen(lopt) : 0; 278 } 279 280 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) 281 { 282 return listen_sock_young(queue->listen_opt); 283 } 284 285 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue) 286 { 287 return reqsk_queue_len(queue) >> queue->listen_opt->max_qlen_log; 288 } 289 290 void reqsk_queue_hash_req(struct request_sock_queue *queue, 291 u32 hash, struct request_sock *req, 292 unsigned long timeout); 293 294 #endif /* _REQUEST_SOCK_H */ 295