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 struct inet6_timewait_sock *tw6; 60 61 tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot); 62 tw6 = inet6_twsk((struct sock *)tw); 63 tw6->tw_v6_daddr = np->daddr; 64 tw6->tw_v6_rcv_saddr = np->rcv_saddr; 65 tw->tw_ipv6only = np->ipv6only; 66 } 67 #endif 68 /* Linkage updates. */ 69 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo); 70 71 /* Get the TIME_WAIT timeout firing. */ 72 if (timeo < rto) 73 timeo = rto; 74 75 tw->tw_timeout = DCCP_TIMEWAIT_LEN; 76 if (state == DCCP_TIME_WAIT) 77 timeo = DCCP_TIMEWAIT_LEN; 78 79 inet_twsk_schedule(tw, &dccp_death_row, timeo, 80 DCCP_TIMEWAIT_LEN); 81 inet_twsk_put(tw); 82 } else { 83 /* Sorry, if we're out of memory, just CLOSE this 84 * socket up. We've got bigger problems than 85 * non-graceful socket closings. 86 */ 87 DCCP_WARN("time wait bucket table overflow\n"); 88 } 89 90 dccp_done(sk); 91 } 92 93 struct sock *dccp_create_openreq_child(struct sock *sk, 94 const struct request_sock *req, 95 const struct sk_buff *skb) 96 { 97 /* 98 * Step 3: Process LISTEN state 99 * 100 * (* Generate a new socket and switch to that socket *) 101 * Set S := new socket for this port pair 102 */ 103 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); 104 105 if (newsk != NULL) { 106 struct dccp_request_sock *dreq = dccp_rsk(req); 107 struct inet_connection_sock *newicsk = inet_csk(newsk); 108 struct dccp_sock *newdp = dccp_sk(newsk); 109 110 newdp->dccps_role = DCCP_ROLE_SERVER; 111 newdp->dccps_hc_rx_ackvec = NULL; 112 newdp->dccps_service_list = NULL; 113 newdp->dccps_service = dreq->dreq_service; 114 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; 115 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; 116 newicsk->icsk_rto = DCCP_TIMEOUT_INIT; 117 118 INIT_LIST_HEAD(&newdp->dccps_featneg); 119 /* 120 * Step 3: Process LISTEN state 121 * 122 * Choose S.ISS (initial seqno) or set from Init Cookies 123 * Initialize S.GAR := S.ISS 124 * Set S.ISR, S.GSR from packet (or Init Cookies) 125 * 126 * Setting AWL/AWH and SWL/SWH happens as part of the feature 127 * activation below, as these windows all depend on the local 128 * and remote Sequence Window feature values (7.5.2). 129 */ 130 newdp->dccps_iss = dreq->dreq_iss; 131 newdp->dccps_gss = dreq->dreq_gss; 132 newdp->dccps_gar = newdp->dccps_iss; 133 newdp->dccps_isr = dreq->dreq_isr; 134 newdp->dccps_gsr = dreq->dreq_gsr; 135 136 /* 137 * Activate features: initialise CCIDs, sequence windows etc. 138 */ 139 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) { 140 /* It is still raw copy of parent, so invalidate 141 * destructor and make plain sk_free() */ 142 newsk->sk_destruct = NULL; 143 sk_free(newsk); 144 return NULL; 145 } 146 dccp_init_xmit_timers(newsk); 147 148 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS); 149 } 150 return newsk; 151 } 152 153 EXPORT_SYMBOL_GPL(dccp_create_openreq_child); 154 155 /* 156 * Process an incoming packet for RESPOND sockets represented 157 * as an request_sock. 158 */ 159 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb, 160 struct request_sock *req, 161 struct request_sock **prev) 162 { 163 struct sock *child = NULL; 164 struct dccp_request_sock *dreq = dccp_rsk(req); 165 166 /* Check for retransmitted REQUEST */ 167 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) { 168 169 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) { 170 dccp_pr_debug("Retransmitted REQUEST\n"); 171 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq; 172 /* 173 * Send another RESPONSE packet 174 * To protect against Request floods, increment retrans 175 * counter (backoff, monitored by dccp_response_timer). 176 */ 177 inet_rtx_syn_ack(sk, req); 178 } 179 /* Network Duplicate, discard packet */ 180 return NULL; 181 } 182 183 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 184 185 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK && 186 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK) 187 goto drop; 188 189 /* Invalid ACK */ 190 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 191 dreq->dreq_iss, dreq->dreq_gss)) { 192 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, " 193 "dreq_iss=%llu, dreq_gss=%llu\n", 194 (unsigned long long) 195 DCCP_SKB_CB(skb)->dccpd_ack_seq, 196 (unsigned long long) dreq->dreq_iss, 197 (unsigned long long) dreq->dreq_gss); 198 goto drop; 199 } 200 201 if (dccp_parse_options(sk, dreq, skb)) 202 goto drop; 203 204 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL); 205 if (child == NULL) 206 goto listen_overflow; 207 208 inet_csk_reqsk_queue_unlink(sk, req, prev); 209 inet_csk_reqsk_queue_removed(sk, req); 210 inet_csk_reqsk_queue_add(sk, req, child); 211 out: 212 return child; 213 listen_overflow: 214 dccp_pr_debug("listen_overflow!\n"); 215 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 216 drop: 217 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET) 218 req->rsk_ops->send_reset(sk, skb); 219 220 inet_csk_reqsk_queue_drop(sk, req, prev); 221 goto out; 222 } 223 224 EXPORT_SYMBOL_GPL(dccp_check_req); 225 226 /* 227 * Queue segment on the new socket if the new socket is active, 228 * otherwise we just shortcircuit this and continue with 229 * the new socket. 230 */ 231 int dccp_child_process(struct sock *parent, struct sock *child, 232 struct sk_buff *skb) 233 { 234 int ret = 0; 235 const int state = child->sk_state; 236 237 if (!sock_owned_by_user(child)) { 238 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb), 239 skb->len); 240 241 /* Wakeup parent, send SIGIO */ 242 if (state == DCCP_RESPOND && child->sk_state != state) 243 parent->sk_data_ready(parent, 0); 244 } else { 245 /* Alas, it is possible again, because we do lookup 246 * in main socket hash table and lock on listening 247 * socket does not protect us more. 248 */ 249 __sk_add_backlog(child, skb); 250 } 251 252 bh_unlock_sock(child); 253 sock_put(child); 254 return ret; 255 } 256 257 EXPORT_SYMBOL_GPL(dccp_child_process); 258 259 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, 260 struct request_sock *rsk) 261 { 262 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state"); 263 } 264 265 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack); 266 267 int dccp_reqsk_init(struct request_sock *req, 268 struct dccp_sock const *dp, struct sk_buff const *skb) 269 { 270 struct dccp_request_sock *dreq = dccp_rsk(req); 271 272 inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport; 273 inet_rsk(req)->loc_port = dccp_hdr(skb)->dccph_dport; 274 inet_rsk(req)->acked = 0; 275 dreq->dreq_timestamp_echo = 0; 276 277 /* inherit feature negotiation options from listening socket */ 278 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg); 279 } 280 281 EXPORT_SYMBOL_GPL(dccp_reqsk_init); 282