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 .period = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS, 31 .death_lock = __SPIN_LOCK_UNLOCKED(dccp_death_row.death_lock), 32 .hashinfo = &dccp_hashinfo, 33 .tw_timer = TIMER_INITIALIZER(inet_twdr_hangman, 0, 34 (unsigned long)&dccp_death_row), 35 .twkill_work = __WORK_INITIALIZER(dccp_death_row.twkill_work, 36 inet_twdr_twkill_work), 37 /* Short-time timewait calendar */ 38 39 .twcal_hand = -1, 40 .twcal_timer = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0, 41 (unsigned long)&dccp_death_row), 42 }; 43 44 EXPORT_SYMBOL_GPL(dccp_death_row); 45 46 void dccp_time_wait(struct sock *sk, int state, int timeo) 47 { 48 struct inet_timewait_sock *tw = NULL; 49 50 if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets) 51 tw = inet_twsk_alloc(sk, state); 52 53 if (tw != NULL) { 54 const struct inet_connection_sock *icsk = inet_csk(sk); 55 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1); 56 #if IS_ENABLED(CONFIG_IPV6) 57 if (tw->tw_family == PF_INET6) { 58 tw->tw_v6_daddr = sk->sk_v6_daddr; 59 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 60 tw->tw_ipv6only = sk->sk_ipv6only; 61 } 62 #endif 63 /* Linkage updates. */ 64 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo); 65 66 /* Get the TIME_WAIT timeout firing. */ 67 if (timeo < rto) 68 timeo = rto; 69 70 tw->tw_timeout = DCCP_TIMEWAIT_LEN; 71 if (state == DCCP_TIME_WAIT) 72 timeo = DCCP_TIMEWAIT_LEN; 73 74 inet_twsk_schedule(tw, &dccp_death_row, timeo, 75 DCCP_TIMEWAIT_LEN); 76 inet_twsk_put(tw); 77 } else { 78 /* Sorry, if we're out of memory, just CLOSE this 79 * socket up. We've got bigger problems than 80 * non-graceful socket closings. 81 */ 82 DCCP_WARN("time wait bucket table overflow\n"); 83 } 84 85 dccp_done(sk); 86 } 87 88 struct sock *dccp_create_openreq_child(struct sock *sk, 89 const struct request_sock *req, 90 const struct sk_buff *skb) 91 { 92 /* 93 * Step 3: Process LISTEN state 94 * 95 * (* Generate a new socket and switch to that socket *) 96 * Set S := new socket for this port pair 97 */ 98 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); 99 100 if (newsk != NULL) { 101 struct dccp_request_sock *dreq = dccp_rsk(req); 102 struct inet_connection_sock *newicsk = inet_csk(newsk); 103 struct dccp_sock *newdp = dccp_sk(newsk); 104 105 newdp->dccps_role = DCCP_ROLE_SERVER; 106 newdp->dccps_hc_rx_ackvec = NULL; 107 newdp->dccps_service_list = NULL; 108 newdp->dccps_service = dreq->dreq_service; 109 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; 110 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; 111 newicsk->icsk_rto = DCCP_TIMEOUT_INIT; 112 113 INIT_LIST_HEAD(&newdp->dccps_featneg); 114 /* 115 * Step 3: Process LISTEN state 116 * 117 * Choose S.ISS (initial seqno) or set from Init Cookies 118 * Initialize S.GAR := S.ISS 119 * Set S.ISR, S.GSR from packet (or Init Cookies) 120 * 121 * Setting AWL/AWH and SWL/SWH happens as part of the feature 122 * activation below, as these windows all depend on the local 123 * and remote Sequence Window feature values (7.5.2). 124 */ 125 newdp->dccps_iss = dreq->dreq_iss; 126 newdp->dccps_gss = dreq->dreq_gss; 127 newdp->dccps_gar = newdp->dccps_iss; 128 newdp->dccps_isr = dreq->dreq_isr; 129 newdp->dccps_gsr = dreq->dreq_gsr; 130 131 /* 132 * Activate features: initialise CCIDs, sequence windows etc. 133 */ 134 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) { 135 /* It is still raw copy of parent, so invalidate 136 * destructor and make plain sk_free() */ 137 newsk->sk_destruct = NULL; 138 sk_free(newsk); 139 return NULL; 140 } 141 dccp_init_xmit_timers(newsk); 142 143 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS); 144 } 145 return newsk; 146 } 147 148 EXPORT_SYMBOL_GPL(dccp_create_openreq_child); 149 150 /* 151 * Process an incoming packet for RESPOND sockets represented 152 * as an request_sock. 153 */ 154 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb, 155 struct request_sock *req, 156 struct request_sock **prev) 157 { 158 struct sock *child = NULL; 159 struct dccp_request_sock *dreq = dccp_rsk(req); 160 161 /* Check for retransmitted REQUEST */ 162 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) { 163 164 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) { 165 dccp_pr_debug("Retransmitted REQUEST\n"); 166 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq; 167 /* 168 * Send another RESPONSE packet 169 * To protect against Request floods, increment retrans 170 * counter (backoff, monitored by dccp_response_timer). 171 */ 172 inet_rtx_syn_ack(sk, req); 173 } 174 /* Network Duplicate, discard packet */ 175 return NULL; 176 } 177 178 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 179 180 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK && 181 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK) 182 goto drop; 183 184 /* Invalid ACK */ 185 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 186 dreq->dreq_iss, dreq->dreq_gss)) { 187 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, " 188 "dreq_iss=%llu, dreq_gss=%llu\n", 189 (unsigned long long) 190 DCCP_SKB_CB(skb)->dccpd_ack_seq, 191 (unsigned long long) dreq->dreq_iss, 192 (unsigned long long) dreq->dreq_gss); 193 goto drop; 194 } 195 196 if (dccp_parse_options(sk, dreq, skb)) 197 goto drop; 198 199 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL); 200 if (child == NULL) 201 goto listen_overflow; 202 203 inet_csk_reqsk_queue_unlink(sk, req, prev); 204 inet_csk_reqsk_queue_removed(sk, req); 205 inet_csk_reqsk_queue_add(sk, req, child); 206 out: 207 return child; 208 listen_overflow: 209 dccp_pr_debug("listen_overflow!\n"); 210 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 211 drop: 212 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET) 213 req->rsk_ops->send_reset(sk, skb); 214 215 inet_csk_reqsk_queue_drop(sk, req, prev); 216 goto out; 217 } 218 219 EXPORT_SYMBOL_GPL(dccp_check_req); 220 221 /* 222 * Queue segment on the new socket if the new socket is active, 223 * otherwise we just shortcircuit this and continue with 224 * the new socket. 225 */ 226 int dccp_child_process(struct sock *parent, struct sock *child, 227 struct sk_buff *skb) 228 { 229 int ret = 0; 230 const int state = child->sk_state; 231 232 if (!sock_owned_by_user(child)) { 233 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb), 234 skb->len); 235 236 /* Wakeup parent, send SIGIO */ 237 if (state == DCCP_RESPOND && child->sk_state != state) 238 parent->sk_data_ready(parent); 239 } else { 240 /* Alas, it is possible again, because we do lookup 241 * in main socket hash table and lock on listening 242 * socket does not protect us more. 243 */ 244 __sk_add_backlog(child, skb); 245 } 246 247 bh_unlock_sock(child); 248 sock_put(child); 249 return ret; 250 } 251 252 EXPORT_SYMBOL_GPL(dccp_child_process); 253 254 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, 255 struct request_sock *rsk) 256 { 257 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state"); 258 } 259 260 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack); 261 262 int dccp_reqsk_init(struct request_sock *req, 263 struct dccp_sock const *dp, struct sk_buff const *skb) 264 { 265 struct dccp_request_sock *dreq = dccp_rsk(req); 266 267 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport; 268 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport); 269 inet_rsk(req)->acked = 0; 270 dreq->dreq_timestamp_echo = 0; 271 272 /* inherit feature negotiation options from listening socket */ 273 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg); 274 } 275 276 EXPORT_SYMBOL_GPL(dccp_reqsk_init); 277