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 const struct ipv6_pinfo *np = inet6_sk(sk); 59 60 tw->tw_v6_daddr = sk->sk_v6_daddr; 61 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 62 tw->tw_ipv6only = np->ipv6only; 63 } 64 #endif 65 /* Linkage updates. */ 66 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo); 67 68 /* Get the TIME_WAIT timeout firing. */ 69 if (timeo < rto) 70 timeo = rto; 71 72 tw->tw_timeout = DCCP_TIMEWAIT_LEN; 73 if (state == DCCP_TIME_WAIT) 74 timeo = DCCP_TIMEWAIT_LEN; 75 76 inet_twsk_schedule(tw, &dccp_death_row, timeo, 77 DCCP_TIMEWAIT_LEN); 78 inet_twsk_put(tw); 79 } else { 80 /* Sorry, if we're out of memory, just CLOSE this 81 * socket up. We've got bigger problems than 82 * non-graceful socket closings. 83 */ 84 DCCP_WARN("time wait bucket table overflow\n"); 85 } 86 87 dccp_done(sk); 88 } 89 90 struct sock *dccp_create_openreq_child(struct sock *sk, 91 const struct request_sock *req, 92 const struct sk_buff *skb) 93 { 94 /* 95 * Step 3: Process LISTEN state 96 * 97 * (* Generate a new socket and switch to that socket *) 98 * Set S := new socket for this port pair 99 */ 100 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); 101 102 if (newsk != NULL) { 103 struct dccp_request_sock *dreq = dccp_rsk(req); 104 struct inet_connection_sock *newicsk = inet_csk(newsk); 105 struct dccp_sock *newdp = dccp_sk(newsk); 106 107 newdp->dccps_role = DCCP_ROLE_SERVER; 108 newdp->dccps_hc_rx_ackvec = NULL; 109 newdp->dccps_service_list = NULL; 110 newdp->dccps_service = dreq->dreq_service; 111 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; 112 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; 113 newicsk->icsk_rto = DCCP_TIMEOUT_INIT; 114 115 INIT_LIST_HEAD(&newdp->dccps_featneg); 116 /* 117 * Step 3: Process LISTEN state 118 * 119 * Choose S.ISS (initial seqno) or set from Init Cookies 120 * Initialize S.GAR := S.ISS 121 * Set S.ISR, S.GSR from packet (or Init Cookies) 122 * 123 * Setting AWL/AWH and SWL/SWH happens as part of the feature 124 * activation below, as these windows all depend on the local 125 * and remote Sequence Window feature values (7.5.2). 126 */ 127 newdp->dccps_iss = dreq->dreq_iss; 128 newdp->dccps_gss = dreq->dreq_gss; 129 newdp->dccps_gar = newdp->dccps_iss; 130 newdp->dccps_isr = dreq->dreq_isr; 131 newdp->dccps_gsr = dreq->dreq_gsr; 132 133 /* 134 * Activate features: initialise CCIDs, sequence windows etc. 135 */ 136 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) { 137 /* It is still raw copy of parent, so invalidate 138 * destructor and make plain sk_free() */ 139 newsk->sk_destruct = NULL; 140 sk_free(newsk); 141 return NULL; 142 } 143 dccp_init_xmit_timers(newsk); 144 145 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS); 146 } 147 return newsk; 148 } 149 150 EXPORT_SYMBOL_GPL(dccp_create_openreq_child); 151 152 /* 153 * Process an incoming packet for RESPOND sockets represented 154 * as an request_sock. 155 */ 156 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb, 157 struct request_sock *req, 158 struct request_sock **prev) 159 { 160 struct sock *child = NULL; 161 struct dccp_request_sock *dreq = dccp_rsk(req); 162 163 /* Check for retransmitted REQUEST */ 164 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) { 165 166 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) { 167 dccp_pr_debug("Retransmitted REQUEST\n"); 168 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq; 169 /* 170 * Send another RESPONSE packet 171 * To protect against Request floods, increment retrans 172 * counter (backoff, monitored by dccp_response_timer). 173 */ 174 inet_rtx_syn_ack(sk, req); 175 } 176 /* Network Duplicate, discard packet */ 177 return NULL; 178 } 179 180 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 181 182 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK && 183 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK) 184 goto drop; 185 186 /* Invalid ACK */ 187 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 188 dreq->dreq_iss, dreq->dreq_gss)) { 189 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, " 190 "dreq_iss=%llu, dreq_gss=%llu\n", 191 (unsigned long long) 192 DCCP_SKB_CB(skb)->dccpd_ack_seq, 193 (unsigned long long) dreq->dreq_iss, 194 (unsigned long long) dreq->dreq_gss); 195 goto drop; 196 } 197 198 if (dccp_parse_options(sk, dreq, skb)) 199 goto drop; 200 201 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL); 202 if (child == NULL) 203 goto listen_overflow; 204 205 inet_csk_reqsk_queue_unlink(sk, req, prev); 206 inet_csk_reqsk_queue_removed(sk, req); 207 inet_csk_reqsk_queue_add(sk, req, child); 208 out: 209 return child; 210 listen_overflow: 211 dccp_pr_debug("listen_overflow!\n"); 212 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 213 drop: 214 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET) 215 req->rsk_ops->send_reset(sk, skb); 216 217 inet_csk_reqsk_queue_drop(sk, req, prev); 218 goto out; 219 } 220 221 EXPORT_SYMBOL_GPL(dccp_check_req); 222 223 /* 224 * Queue segment on the new socket if the new socket is active, 225 * otherwise we just shortcircuit this and continue with 226 * the new socket. 227 */ 228 int dccp_child_process(struct sock *parent, struct sock *child, 229 struct sk_buff *skb) 230 { 231 int ret = 0; 232 const int state = child->sk_state; 233 234 if (!sock_owned_by_user(child)) { 235 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb), 236 skb->len); 237 238 /* Wakeup parent, send SIGIO */ 239 if (state == DCCP_RESPOND && child->sk_state != state) 240 parent->sk_data_ready(parent); 241 } else { 242 /* Alas, it is possible again, because we do lookup 243 * in main socket hash table and lock on listening 244 * socket does not protect us more. 245 */ 246 __sk_add_backlog(child, skb); 247 } 248 249 bh_unlock_sock(child); 250 sock_put(child); 251 return ret; 252 } 253 254 EXPORT_SYMBOL_GPL(dccp_child_process); 255 256 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, 257 struct request_sock *rsk) 258 { 259 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state"); 260 } 261 262 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack); 263 264 int dccp_reqsk_init(struct request_sock *req, 265 struct dccp_sock const *dp, struct sk_buff const *skb) 266 { 267 struct dccp_request_sock *dreq = dccp_rsk(req); 268 269 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport; 270 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport); 271 inet_rsk(req)->acked = 0; 272 dreq->dreq_timestamp_echo = 0; 273 274 /* inherit feature negotiation options from listening socket */ 275 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg); 276 } 277 278 EXPORT_SYMBOL_GPL(dccp_reqsk_init); 279