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 inet_twsk_schedule(tw, timeo); 61 /* Linkage updates. */ 62 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo); 63 inet_twsk_put(tw); 64 } else { 65 /* Sorry, if we're out of memory, just CLOSE this 66 * socket up. We've got bigger problems than 67 * non-graceful socket closings. 68 */ 69 DCCP_WARN("time wait bucket table overflow\n"); 70 } 71 72 dccp_done(sk); 73 } 74 75 struct sock *dccp_create_openreq_child(const struct sock *sk, 76 const struct request_sock *req, 77 const struct sk_buff *skb) 78 { 79 /* 80 * Step 3: Process LISTEN state 81 * 82 * (* Generate a new socket and switch to that socket *) 83 * Set S := new socket for this port pair 84 */ 85 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); 86 87 if (newsk != NULL) { 88 struct dccp_request_sock *dreq = dccp_rsk(req); 89 struct inet_connection_sock *newicsk = inet_csk(newsk); 90 struct dccp_sock *newdp = dccp_sk(newsk); 91 92 newdp->dccps_role = DCCP_ROLE_SERVER; 93 newdp->dccps_hc_rx_ackvec = NULL; 94 newdp->dccps_service_list = NULL; 95 newdp->dccps_service = dreq->dreq_service; 96 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; 97 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; 98 newicsk->icsk_rto = DCCP_TIMEOUT_INIT; 99 100 INIT_LIST_HEAD(&newdp->dccps_featneg); 101 /* 102 * Step 3: Process LISTEN state 103 * 104 * Choose S.ISS (initial seqno) or set from Init Cookies 105 * Initialize S.GAR := S.ISS 106 * Set S.ISR, S.GSR from packet (or Init Cookies) 107 * 108 * Setting AWL/AWH and SWL/SWH happens as part of the feature 109 * activation below, as these windows all depend on the local 110 * and remote Sequence Window feature values (7.5.2). 111 */ 112 newdp->dccps_iss = dreq->dreq_iss; 113 newdp->dccps_gss = dreq->dreq_gss; 114 newdp->dccps_gar = newdp->dccps_iss; 115 newdp->dccps_isr = dreq->dreq_isr; 116 newdp->dccps_gsr = dreq->dreq_gsr; 117 118 /* 119 * Activate features: initialise CCIDs, sequence windows etc. 120 */ 121 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) { 122 sk_free_unlock_clone(newsk); 123 return NULL; 124 } 125 dccp_init_xmit_timers(newsk); 126 127 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS); 128 } 129 return newsk; 130 } 131 132 EXPORT_SYMBOL_GPL(dccp_create_openreq_child); 133 134 /* 135 * Process an incoming packet for RESPOND sockets represented 136 * as an request_sock. 137 */ 138 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb, 139 struct request_sock *req) 140 { 141 struct sock *child = NULL; 142 struct dccp_request_sock *dreq = dccp_rsk(req); 143 bool own_req; 144 145 /* TCP/DCCP listeners became lockless. 146 * DCCP stores complex state in its request_sock, so we need 147 * a protection for them, now this code runs without being protected 148 * by the parent (listener) lock. 149 */ 150 spin_lock_bh(&dreq->dreq_lock); 151 152 /* Check for retransmitted REQUEST */ 153 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) { 154 155 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) { 156 dccp_pr_debug("Retransmitted REQUEST\n"); 157 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq; 158 /* 159 * Send another RESPONSE packet 160 * To protect against Request floods, increment retrans 161 * counter (backoff, monitored by dccp_response_timer). 162 */ 163 inet_rtx_syn_ack(sk, req); 164 } 165 /* Network Duplicate, discard packet */ 166 goto out; 167 } 168 169 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 170 171 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK && 172 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK) 173 goto drop; 174 175 /* Invalid ACK */ 176 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 177 dreq->dreq_iss, dreq->dreq_gss)) { 178 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, " 179 "dreq_iss=%llu, dreq_gss=%llu\n", 180 (unsigned long long) 181 DCCP_SKB_CB(skb)->dccpd_ack_seq, 182 (unsigned long long) dreq->dreq_iss, 183 (unsigned long long) dreq->dreq_gss); 184 goto drop; 185 } 186 187 if (dccp_parse_options(sk, dreq, skb)) 188 goto drop; 189 190 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, 191 req, &own_req); 192 if (child) { 193 child = inet_csk_complete_hashdance(sk, child, req, own_req); 194 goto out; 195 } 196 197 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 198 drop: 199 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET) 200 req->rsk_ops->send_reset(sk, skb); 201 202 inet_csk_reqsk_queue_drop(sk, req); 203 out: 204 spin_unlock_bh(&dreq->dreq_lock); 205 return child; 206 } 207 208 EXPORT_SYMBOL_GPL(dccp_check_req); 209 210 /* 211 * Queue segment on the new socket if the new socket is active, 212 * otherwise we just shortcircuit this and continue with 213 * the new socket. 214 */ 215 int dccp_child_process(struct sock *parent, struct sock *child, 216 struct sk_buff *skb) 217 { 218 int ret = 0; 219 const int state = child->sk_state; 220 221 if (!sock_owned_by_user(child)) { 222 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb), 223 skb->len); 224 225 /* Wakeup parent, send SIGIO */ 226 if (state == DCCP_RESPOND && child->sk_state != state) 227 parent->sk_data_ready(parent); 228 } else { 229 /* Alas, it is possible again, because we do lookup 230 * in main socket hash table and lock on listening 231 * socket does not protect us more. 232 */ 233 __sk_add_backlog(child, skb); 234 } 235 236 bh_unlock_sock(child); 237 sock_put(child); 238 return ret; 239 } 240 241 EXPORT_SYMBOL_GPL(dccp_child_process); 242 243 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, 244 struct request_sock *rsk) 245 { 246 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state"); 247 } 248 249 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack); 250 251 int dccp_reqsk_init(struct request_sock *req, 252 struct dccp_sock const *dp, struct sk_buff const *skb) 253 { 254 struct dccp_request_sock *dreq = dccp_rsk(req); 255 256 spin_lock_init(&dreq->dreq_lock); 257 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport; 258 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport); 259 inet_rsk(req)->acked = 0; 260 dreq->dreq_timestamp_echo = 0; 261 262 /* inherit feature negotiation options from listening socket */ 263 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg); 264 } 265 266 EXPORT_SYMBOL_GPL(dccp_reqsk_init); 267