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   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
  22 #include <net/sock.h>
  23
  24 struct request_sock;
  25 struct sk_buff;
  26 struct dst_entry;
  27 struct proto;
  28
  29 struct request_sock_ops {
  30         int             family;
  31         int             obj_size;
  32         kmem_cache_t    *slab;
  33         int             (*rtx_syn_ack)(struct sock *sk,
  34                                        struct request_sock *req,
  35                                        struct dst_entry *dst);
  36         void            (*send_ack)(struct sk_buff *skb,
  37                                     struct request_sock *req);
  38         void            (*send_reset)(struct sock *sk,
  39                                       struct sk_buff *skb);
  40         void            (*destructor)(struct request_sock *req);
  41 };
  42
  43 /* struct request_sock - mini sock to represent a connection request
  44  */
  45 struct request_sock {
  46         struct request_sock             *dl_next; /* Must be first member! */
  47         u16                             mss;
  48         u8                              retrans;
  49         u8                              __pad;
  50         /* The following two fields can be easily recomputed I think -AK */
  51         u32                             window_clamp; /* window clamp at creation time */
  52         u32                             rcv_wnd;          /* rcv_wnd offered first time */
  53         u32                             ts_recent;
  54         unsigned long                   expires;
  55         const struct request_sock_ops   *rsk_ops;
  56         struct sock                     *sk;
  57         u32                             secid;
  58         u32                             peer_secid;
  59 };
  60
  61 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
  62 {
  63         struct request_sock *req = kmem_cache_alloc(ops->slab, SLAB_ATOMIC);
  64
  65         if (req != NULL)
  66                 req->rsk_ops = ops;
  67
  68         return req;
  69 }
  70
  71 static inline void __reqsk_free(struct request_sock *req)
  72 {
  73         kmem_cache_free(req->rsk_ops->slab, req);
  74 }
  75
  76 static inline void reqsk_free(struct request_sock *req)
  77 {
  78         req->rsk_ops->destructor(req);
  79         __reqsk_free(req);
  80 }
  81
  82 extern int sysctl_max_syn_backlog;
  83
  84 /** struct listen_sock - listen state
  85  *
  86  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
  87  */
  88 struct listen_sock {
  89         u8                      max_qlen_log;
  90         /* 3 bytes hole, try to use */
  91         int                     qlen;
  92         int                     qlen_young;
  93         int                     clock_hand;
  94         u32                     hash_rnd;
  95         u32                     nr_table_entries;
  96         struct request_sock     *syn_table[0];
  97 };
  98
  99 /** struct request_sock_queue - queue of request_socks
 100  *
 101  * @rskq_accept_head - FIFO head of established children
 102  * @rskq_accept_tail - FIFO tail of established children
 103  * @rskq_defer_accept - User waits for some data after accept()
 104  * @syn_wait_lock - serializer
 105  *
 106  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
 107  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
 108  *
 109  * This lock is acquired in read mode only from listening_get_next() seq_file
 110  * op and it's acquired in write mode _only_ from code that is actively
 111  * changing rskq_accept_head. All readers that are holding the master sock lock
 112  * don't need to grab this lock in read mode too as rskq_accept_head. writes
 113  * are always protected from the main sock lock.
 114  */
 115 struct request_sock_queue {
 116         struct request_sock     *rskq_accept_head;
 117         struct request_sock     *rskq_accept_tail;
 118         rwlock_t                syn_wait_lock;
 119         u8                      rskq_defer_accept;
 120         /* 3 bytes hole, try to pack */
 121         struct listen_sock      *listen_opt;
 122 };
 123
 124 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 125                              unsigned int nr_table_entries);
 126
 127 static inline struct listen_sock *reqsk_queue_yank_listen_sk(struct request_sock_queue *queue)
 128 {
 129         struct listen_sock *lopt;
 130
 131         write_lock_bh(&queue->syn_wait_lock);
 132         lopt = queue->listen_opt;
 133         queue->listen_opt = NULL;
 134         write_unlock_bh(&queue->syn_wait_lock);
 135
 136         return lopt;
 137 }
 138
 139 static inline void __reqsk_queue_destroy(struct request_sock_queue *queue)
 140 {
 141         kfree(reqsk_queue_yank_listen_sk(queue));
 142 }
 143
 144 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 145
 146 static inline struct request_sock *
 147         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
 148 {
 149         struct request_sock *req = queue->rskq_accept_head;
 150
 151         queue->rskq_accept_head = NULL;
 152         return req;
 153 }
 154
 155 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 156 {
 157         return queue->rskq_accept_head == NULL;
 158 }
 159
 160 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
 161                                       struct request_sock *req,
 162                                       struct request_sock **prev_req)
 163 {
 164         write_lock(&queue->syn_wait_lock);
 165         *prev_req = req->dl_next;
 166         write_unlock(&queue->syn_wait_lock);
 167 }
 168
 169 static inline void reqsk_queue_add(struct request_sock_queue *queue,
 170                                    struct request_sock *req,
 171                                    struct sock *parent,
 172                                    struct sock *child)
 173 {
 174         req->sk = child;
 175         sk_acceptq_added(parent);
 176
 177         if (queue->rskq_accept_head == NULL)
 178                 queue->rskq_accept_head = req;
 179         else
 180                 queue->rskq_accept_tail->dl_next = req;
 181
 182         queue->rskq_accept_tail = req;
 183         req->dl_next = NULL;
 184 }
 185
 186 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 187 {
 188         struct request_sock *req = queue->rskq_accept_head;
 189
 190         BUG_TRAP(req != NULL);
 191
 192         queue->rskq_accept_head = req->dl_next;
 193         if (queue->rskq_accept_head == NULL)
 194                 queue->rskq_accept_tail = NULL;
 195
 196         return req;
 197 }
 198
 199 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
 200                                                  struct sock *parent)
 201 {
 202         struct request_sock *req = reqsk_queue_remove(queue);
 203         struct sock *child = req->sk;
 204
 205         BUG_TRAP(child != NULL);
 206
 207         sk_acceptq_removed(parent);
 208         __reqsk_free(req);
 209         return child;
 210 }
 211
 212 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
 213                                       struct request_sock *req)
 214 {
 215         struct listen_sock *lopt = queue->listen_opt;
 216
 217         if (req->retrans == 0)
 218                 --lopt->qlen_young;
 219
 220         return --lopt->qlen;
 221 }
 222
 223 static inline int reqsk_queue_added(struct request_sock_queue *queue)
 224 {
 225         struct listen_sock *lopt = queue->listen_opt;
 226         const int prev_qlen = lopt->qlen;
 227
 228         lopt->qlen_young++;
 229         lopt->qlen++;
 230         return prev_qlen;
 231 }
 232
 233 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
 234 {
 235         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 236 }
 237
 238 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 239 {
 240         return queue->listen_opt->qlen_young;
 241 }
 242
 243 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
 244 {
 245         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 246 }
 247
 248 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 249                                         u32 hash, struct request_sock *req,
 250                                         unsigned long timeout)
 251 {
 252         struct listen_sock *lopt = queue->listen_opt;
 253
 254         req->expires = jiffies + timeout;
 255         req->retrans = 0;
 256         req->sk = NULL;
 257         req->dl_next = lopt->syn_table[hash];
 258
 259         write_lock(&queue->syn_wait_lock);
 260         lopt->syn_table[hash] = req;
 261         write_unlock(&queue->syn_wait_lock);
 262 }
 263
 264 #endif /* _REQUEST_SOCK_H */