1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * NET Generic infrastructure for Network protocols. 4 * 5 * Definitions for request_sock 6 * 7 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br> 8 * 9 * From code originally in include/net/tcp.h 10 */ 11 #ifndef _REQUEST_SOCK_H 12 #define _REQUEST_SOCK_H 13 14 #include <linux/slab.h> 15 #include <linux/spinlock.h> 16 #include <linux/types.h> 17 #include <linux/bug.h> 18 #include <linux/refcount.h> 19 20 #include <net/sock.h> 21 22 struct request_sock; 23 struct sk_buff; 24 struct dst_entry; 25 struct proto; 26 27 struct request_sock_ops { 28 int family; 29 unsigned int obj_size; 30 struct kmem_cache *slab; 31 char *slab_name; 32 int (*rtx_syn_ack)(const struct sock *sk, 33 struct request_sock *req); 34 void (*send_ack)(const struct sock *sk, struct sk_buff *skb, 35 struct request_sock *req); 36 void (*send_reset)(const struct sock *sk, 37 struct sk_buff *skb); 38 void (*destructor)(struct request_sock *req); 39 void (*syn_ack_timeout)(const struct request_sock *req); 40 }; 41 42 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req); 43 44 /* struct request_sock - mini sock to represent a connection request 45 */ 46 struct request_sock { 47 struct sock_common __req_common; 48 #define rsk_refcnt __req_common.skc_refcnt 49 #define rsk_hash __req_common.skc_hash 50 #define rsk_listener __req_common.skc_listener 51 #define rsk_window_clamp __req_common.skc_window_clamp 52 #define rsk_rcv_wnd __req_common.skc_rcv_wnd 53 54 struct request_sock *dl_next; 55 u16 mss; 56 u8 num_retrans; /* number of retransmits */ 57 u8 cookie_ts:1; /* syncookie: encode tcpopts in timestamp */ 58 u8 num_timeout:7; /* number of timeouts */ 59 u32 ts_recent; 60 struct timer_list rsk_timer; 61 const struct request_sock_ops *rsk_ops; 62 struct sock *sk; 63 u32 *saved_syn; 64 u32 secid; 65 u32 peer_secid; 66 }; 67 68 static inline struct request_sock *inet_reqsk(const struct sock *sk) 69 { 70 return (struct request_sock *)sk; 71 } 72 73 static inline struct sock *req_to_sk(struct request_sock *req) 74 { 75 return (struct sock *)req; 76 } 77 78 static inline struct request_sock * 79 reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener, 80 bool attach_listener) 81 { 82 struct request_sock *req; 83 84 req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN); 85 if (!req) 86 return NULL; 87 req->rsk_listener = NULL; 88 if (attach_listener) { 89 if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) { 90 kmem_cache_free(ops->slab, req); 91 return NULL; 92 } 93 req->rsk_listener = sk_listener; 94 } 95 req->rsk_ops = ops; 96 req_to_sk(req)->sk_prot = sk_listener->sk_prot; 97 sk_node_init(&req_to_sk(req)->sk_node); 98 sk_tx_queue_clear(req_to_sk(req)); 99 req->saved_syn = NULL; 100 refcount_set(&req->rsk_refcnt, 0); 101 102 return req; 103 } 104 105 static inline void __reqsk_free(struct request_sock *req) 106 { 107 req->rsk_ops->destructor(req); 108 if (req->rsk_listener) 109 sock_put(req->rsk_listener); 110 kfree(req->saved_syn); 111 kmem_cache_free(req->rsk_ops->slab, req); 112 } 113 114 static inline void reqsk_free(struct request_sock *req) 115 { 116 WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0); 117 __reqsk_free(req); 118 } 119 120 static inline void reqsk_put(struct request_sock *req) 121 { 122 if (refcount_dec_and_test(&req->rsk_refcnt)) 123 reqsk_free(req); 124 } 125 126 /* 127 * For a TCP Fast Open listener - 128 * lock - protects the access to all the reqsk, which is co-owned by 129 * the listener and the child socket. 130 * qlen - pending TFO requests (still in TCP_SYN_RECV). 131 * max_qlen - max TFO reqs allowed before TFO is disabled. 132 * 133 * XXX (TFO) - ideally these fields can be made as part of "listen_sock" 134 * structure above. But there is some implementation difficulty due to 135 * listen_sock being part of request_sock_queue hence will be freed when 136 * a listener is stopped. But TFO related fields may continue to be 137 * accessed even after a listener is closed, until its sk_refcnt drops 138 * to 0 implying no more outstanding TFO reqs. One solution is to keep 139 * listen_opt around until sk_refcnt drops to 0. But there is some other 140 * complexity that needs to be resolved. E.g., a listener can be disabled 141 * temporarily through shutdown()->tcp_disconnect(), and re-enabled later. 142 */ 143 struct fastopen_queue { 144 struct request_sock *rskq_rst_head; /* Keep track of past TFO */ 145 struct request_sock *rskq_rst_tail; /* requests that caused RST. 146 * This is part of the defense 147 * against spoofing attack. 148 */ 149 spinlock_t lock; 150 int qlen; /* # of pending (TCP_SYN_RECV) reqs */ 151 int max_qlen; /* != 0 iff TFO is currently enabled */ 152 153 struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */ 154 }; 155 156 /** struct request_sock_queue - queue of request_socks 157 * 158 * @rskq_accept_head - FIFO head of established children 159 * @rskq_accept_tail - FIFO tail of established children 160 * @rskq_defer_accept - User waits for some data after accept() 161 * 162 */ 163 struct request_sock_queue { 164 spinlock_t rskq_lock; 165 u8 rskq_defer_accept; 166 167 u32 synflood_warned; 168 atomic_t qlen; 169 atomic_t young; 170 171 struct request_sock *rskq_accept_head; 172 struct request_sock *rskq_accept_tail; 173 struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine 174 * if TFO is enabled. 175 */ 176 }; 177 178 void reqsk_queue_alloc(struct request_sock_queue *queue); 179 180 void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req, 181 bool reset); 182 183 static inline bool reqsk_queue_empty(const struct request_sock_queue *queue) 184 { 185 return queue->rskq_accept_head == NULL; 186 } 187 188 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue, 189 struct sock *parent) 190 { 191 struct request_sock *req; 192 193 spin_lock_bh(&queue->rskq_lock); 194 req = queue->rskq_accept_head; 195 if (req) { 196 sk_acceptq_removed(parent); 197 queue->rskq_accept_head = req->dl_next; 198 if (queue->rskq_accept_head == NULL) 199 queue->rskq_accept_tail = NULL; 200 } 201 spin_unlock_bh(&queue->rskq_lock); 202 return req; 203 } 204 205 static inline void reqsk_queue_removed(struct request_sock_queue *queue, 206 const struct request_sock *req) 207 { 208 if (req->num_timeout == 0) 209 atomic_dec(&queue->young); 210 atomic_dec(&queue->qlen); 211 } 212 213 static inline void reqsk_queue_added(struct request_sock_queue *queue) 214 { 215 atomic_inc(&queue->young); 216 atomic_inc(&queue->qlen); 217 } 218 219 static inline int reqsk_queue_len(const struct request_sock_queue *queue) 220 { 221 return atomic_read(&queue->qlen); 222 } 223 224 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) 225 { 226 return atomic_read(&queue->young); 227 } 228 229 #endif /* _REQUEST_SOCK_H */ 230