1 /* 2 * net/dccp/minisocks.c 3 * 4 * An implementation of the DCCP protocol 5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 */ 12 13 #include <linux/dccp.h> 14 #include <linux/gfp.h> 15 #include <linux/kernel.h> 16 #include <linux/skbuff.h> 17 #include <linux/timer.h> 18 19 #include <net/sock.h> 20 #include <net/xfrm.h> 21 #include <net/inet_timewait_sock.h> 22 23 #include "ackvec.h" 24 #include "ccid.h" 25 #include "dccp.h" 26 #include "feat.h" 27 28 struct inet_timewait_death_row dccp_death_row = { 29 .sysctl_max_tw_buckets = NR_FILE * 2, 30 .hashinfo = &dccp_hashinfo, 31 }; 32 33 EXPORT_SYMBOL_GPL(dccp_death_row); 34 35 void dccp_time_wait(struct sock *sk, int state, int timeo) 36 { 37 struct inet_timewait_sock *tw; 38 39 tw = inet_twsk_alloc(sk, &dccp_death_row, state); 40 41 if (tw != NULL) { 42 const struct inet_connection_sock *icsk = inet_csk(sk); 43 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1); 44 #if IS_ENABLED(CONFIG_IPV6) 45 if (tw->tw_family == PF_INET6) { 46 tw->tw_v6_daddr = sk->sk_v6_daddr; 47 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 48 tw->tw_ipv6only = sk->sk_ipv6only; 49 } 50 #endif 51 52 /* Get the TIME_WAIT timeout firing. */ 53 if (timeo < rto) 54 timeo = rto; 55 56 tw->tw_timeout = DCCP_TIMEWAIT_LEN; 57 if (state == DCCP_TIME_WAIT) 58 timeo = DCCP_TIMEWAIT_LEN; 59 60 /* tw_timer is pinned, so we need to make sure BH are disabled 61 * in following section, otherwise timer handler could run before 62 * we complete the initialization. 63 */ 64 local_bh_disable(); 65 inet_twsk_schedule(tw, timeo); 66 /* Linkage updates. 67 * Note that access to tw after this point is illegal. 68 */ 69 inet_twsk_hashdance(tw, sk, &dccp_hashinfo); 70 local_bh_enable(); 71 } else { 72 /* Sorry, if we're out of memory, just CLOSE this 73 * socket up. We've got bigger problems than 74 * non-graceful socket closings. 75 */ 76 DCCP_WARN("time wait bucket table overflow\n"); 77 } 78 79 dccp_done(sk); 80 } 81 82 struct sock *dccp_create_openreq_child(const struct sock *sk, 83 const struct request_sock *req, 84 const struct sk_buff *skb) 85 { 86 /* 87 * Step 3: Process LISTEN state 88 * 89 * (* Generate a new socket and switch to that socket *) 90 * Set S := new socket for this port pair 91 */ 92 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); 93 94 if (newsk != NULL) { 95 struct dccp_request_sock *dreq = dccp_rsk(req); 96 struct inet_connection_sock *newicsk = inet_csk(newsk); 97 struct dccp_sock *newdp = dccp_sk(newsk); 98 99 newdp->dccps_role = DCCP_ROLE_SERVER; 100 newdp->dccps_hc_rx_ackvec = NULL; 101 newdp->dccps_service_list = NULL; 102 newdp->dccps_service = dreq->dreq_service; 103 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; 104 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; 105 newicsk->icsk_rto = DCCP_TIMEOUT_INIT; 106 107 INIT_LIST_HEAD(&newdp->dccps_featneg); 108 /* 109 * Step 3: Process LISTEN state 110 * 111 * Choose S.ISS (initial seqno) or set from Init Cookies 112 * Initialize S.GAR := S.ISS 113 * Set S.ISR, S.GSR from packet (or Init Cookies) 114 * 115 * Setting AWL/AWH and SWL/SWH happens as part of the feature 116 * activation below, as these windows all depend on the local 117 * and remote Sequence Window feature values (7.5.2). 118 */ 119 newdp->dccps_iss = dreq->dreq_iss; 120 newdp->dccps_gss = dreq->dreq_gss; 121 newdp->dccps_gar = newdp->dccps_iss; 122 newdp->dccps_isr = dreq->dreq_isr; 123 newdp->dccps_gsr = dreq->dreq_gsr; 124 125 /* 126 * Activate features: initialise CCIDs, sequence windows etc. 127 */ 128 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) { 129 sk_free_unlock_clone(newsk); 130 return NULL; 131 } 132 dccp_init_xmit_timers(newsk); 133 134 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS); 135 } 136 return newsk; 137 } 138 139 EXPORT_SYMBOL_GPL(dccp_create_openreq_child); 140 141 /* 142 * Process an incoming packet for RESPOND sockets represented 143 * as an request_sock. 144 */ 145 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb, 146 struct request_sock *req) 147 { 148 struct sock *child = NULL; 149 struct dccp_request_sock *dreq = dccp_rsk(req); 150 bool own_req; 151 152 /* TCP/DCCP listeners became lockless. 153 * DCCP stores complex state in its request_sock, so we need 154 * a protection for them, now this code runs without being protected 155 * by the parent (listener) lock. 156 */ 157 spin_lock_bh(&dreq->dreq_lock); 158 159 /* Check for retransmitted REQUEST */ 160 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) { 161 162 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) { 163 dccp_pr_debug("Retransmitted REQUEST\n"); 164 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq; 165 /* 166 * Send another RESPONSE packet 167 * To protect against Request floods, increment retrans 168 * counter (backoff, monitored by dccp_response_timer). 169 */ 170 inet_rtx_syn_ack(sk, req); 171 } 172 /* Network Duplicate, discard packet */ 173 goto out; 174 } 175 176 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 177 178 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK && 179 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK) 180 goto drop; 181 182 /* Invalid ACK */ 183 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 184 dreq->dreq_iss, dreq->dreq_gss)) { 185 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, " 186 "dreq_iss=%llu, dreq_gss=%llu\n", 187 (unsigned long long) 188 DCCP_SKB_CB(skb)->dccpd_ack_seq, 189 (unsigned long long) dreq->dreq_iss, 190 (unsigned long long) dreq->dreq_gss); 191 goto drop; 192 } 193 194 if (dccp_parse_options(sk, dreq, skb)) 195 goto drop; 196 197 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, 198 req, &own_req); 199 if (child) { 200 child = inet_csk_complete_hashdance(sk, child, req, own_req); 201 goto out; 202 } 203 204 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 205 drop: 206 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET) 207 req->rsk_ops->send_reset(sk, skb); 208 209 inet_csk_reqsk_queue_drop(sk, req); 210 out: 211 spin_unlock_bh(&dreq->dreq_lock); 212 return child; 213 } 214 215 EXPORT_SYMBOL_GPL(dccp_check_req); 216 217 /* 218 * Queue segment on the new socket if the new socket is active, 219 * otherwise we just shortcircuit this and continue with 220 * the new socket. 221 */ 222 int dccp_child_process(struct sock *parent, struct sock *child, 223 struct sk_buff *skb) 224 { 225 int ret = 0; 226 const int state = child->sk_state; 227 228 if (!sock_owned_by_user(child)) { 229 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb), 230 skb->len); 231 232 /* Wakeup parent, send SIGIO */ 233 if (state == DCCP_RESPOND && child->sk_state != state) 234 parent->sk_data_ready(parent); 235 } else { 236 /* Alas, it is possible again, because we do lookup 237 * in main socket hash table and lock on listening 238 * socket does not protect us more. 239 */ 240 __sk_add_backlog(child, skb); 241 } 242 243 bh_unlock_sock(child); 244 sock_put(child); 245 return ret; 246 } 247 248 EXPORT_SYMBOL_GPL(dccp_child_process); 249 250 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, 251 struct request_sock *rsk) 252 { 253 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state"); 254 } 255 256 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack); 257 258 int dccp_reqsk_init(struct request_sock *req, 259 struct dccp_sock const *dp, struct sk_buff const *skb) 260 { 261 struct dccp_request_sock *dreq = dccp_rsk(req); 262 263 spin_lock_init(&dreq->dreq_lock); 264 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport; 265 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport); 266 inet_rsk(req)->acked = 0; 267 dreq->dreq_timestamp_echo = 0; 268 269 /* inherit feature negotiation options from listening socket */ 270 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg); 271 } 272 273 EXPORT_SYMBOL_GPL(dccp_reqsk_init); 274