1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/dccp/minisocks.c 4 * 5 * An implementation of the DCCP protocol 6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 7 */ 8 9 #include <linux/dccp.h> 10 #include <linux/gfp.h> 11 #include <linux/kernel.h> 12 #include <linux/skbuff.h> 13 #include <linux/timer.h> 14 15 #include <net/sock.h> 16 #include <net/xfrm.h> 17 #include <net/inet_timewait_sock.h> 18 #include <net/rstreason.h> 19 20 #include "ackvec.h" 21 #include "ccid.h" 22 #include "dccp.h" 23 #include "feat.h" 24 25 struct inet_timewait_death_row dccp_death_row = { 26 .tw_refcount = REFCOUNT_INIT(1), 27 .sysctl_max_tw_buckets = NR_FILE * 2, 28 .hashinfo = &dccp_hashinfo, 29 }; 30 31 EXPORT_SYMBOL_GPL(dccp_death_row); 32 33 void dccp_time_wait(struct sock *sk, int state, int timeo) 34 { 35 struct inet_timewait_sock *tw; 36 37 tw = inet_twsk_alloc(sk, &dccp_death_row, state); 38 39 if (tw != NULL) { 40 const struct inet_connection_sock *icsk = inet_csk(sk); 41 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1); 42 #if IS_ENABLED(CONFIG_IPV6) 43 if (tw->tw_family == PF_INET6) { 44 tw->tw_v6_daddr = sk->sk_v6_daddr; 45 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 46 tw->tw_ipv6only = sk->sk_ipv6only; 47 } 48 #endif 49 50 /* Get the TIME_WAIT timeout firing. */ 51 if (timeo < rto) 52 timeo = rto; 53 54 if (state == DCCP_TIME_WAIT) 55 timeo = DCCP_TIMEWAIT_LEN; 56 57 /* Linkage updates. 58 * Note that access to tw after this point is illegal. 59 */ 60 inet_twsk_hashdance_schedule(tw, sk, &dccp_hashinfo, timeo); 61 } else { 62 /* Sorry, if we're out of memory, just CLOSE this 63 * socket up. We've got bigger problems than 64 * non-graceful socket closings. 65 */ 66 DCCP_WARN("time wait bucket table overflow\n"); 67 } 68 69 dccp_done(sk); 70 } 71 72 struct sock *dccp_create_openreq_child(const struct sock *sk, 73 const struct request_sock *req, 74 const struct sk_buff *skb) 75 { 76 /* 77 * Step 3: Process LISTEN state 78 * 79 * (* Generate a new socket and switch to that socket *) 80 * Set S := new socket for this port pair 81 */ 82 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); 83 84 if (newsk != NULL) { 85 struct dccp_request_sock *dreq = dccp_rsk(req); 86 struct inet_connection_sock *newicsk = inet_csk(newsk); 87 struct dccp_sock *newdp = dccp_sk(newsk); 88 89 newdp->dccps_role = DCCP_ROLE_SERVER; 90 newdp->dccps_hc_rx_ackvec = NULL; 91 newdp->dccps_service_list = NULL; 92 newdp->dccps_hc_rx_ccid = NULL; 93 newdp->dccps_hc_tx_ccid = NULL; 94 newdp->dccps_service = dreq->dreq_service; 95 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; 96 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; 97 newicsk->icsk_rto = DCCP_TIMEOUT_INIT; 98 99 INIT_LIST_HEAD(&newdp->dccps_featneg); 100 /* 101 * Step 3: Process LISTEN state 102 * 103 * Choose S.ISS (initial seqno) or set from Init Cookies 104 * Initialize S.GAR := S.ISS 105 * Set S.ISR, S.GSR from packet (or Init Cookies) 106 * 107 * Setting AWL/AWH and SWL/SWH happens as part of the feature 108 * activation below, as these windows all depend on the local 109 * and remote Sequence Window feature values (7.5.2). 110 */ 111 newdp->dccps_iss = dreq->dreq_iss; 112 newdp->dccps_gss = dreq->dreq_gss; 113 newdp->dccps_gar = newdp->dccps_iss; 114 newdp->dccps_isr = dreq->dreq_isr; 115 newdp->dccps_gsr = dreq->dreq_gsr; 116 117 /* 118 * Activate features: initialise CCIDs, sequence windows etc. 119 */ 120 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) { 121 sk_free_unlock_clone(newsk); 122 return NULL; 123 } 124 dccp_init_xmit_timers(newsk); 125 126 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS); 127 } 128 return newsk; 129 } 130 131 EXPORT_SYMBOL_GPL(dccp_create_openreq_child); 132 133 /* 134 * Process an incoming packet for RESPOND sockets represented 135 * as an request_sock. 136 */ 137 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb, 138 struct request_sock *req) 139 { 140 struct sock *child = NULL; 141 struct dccp_request_sock *dreq = dccp_rsk(req); 142 bool own_req; 143 144 /* TCP/DCCP listeners became lockless. 145 * DCCP stores complex state in its request_sock, so we need 146 * a protection for them, now this code runs without being protected 147 * by the parent (listener) lock. 148 */ 149 spin_lock_bh(&dreq->dreq_lock); 150 151 /* Check for retransmitted REQUEST */ 152 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) { 153 154 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) { 155 dccp_pr_debug("Retransmitted REQUEST\n"); 156 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq; 157 /* 158 * Send another RESPONSE packet 159 * To protect against Request floods, increment retrans 160 * counter (backoff, monitored by dccp_response_timer). 161 */ 162 inet_rtx_syn_ack(sk, req); 163 } 164 /* Network Duplicate, discard packet */ 165 goto out; 166 } 167 168 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; 169 170 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK && 171 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK) 172 goto drop; 173 174 /* Invalid ACK */ 175 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, 176 dreq->dreq_iss, dreq->dreq_gss)) { 177 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, " 178 "dreq_iss=%llu, dreq_gss=%llu\n", 179 (unsigned long long) 180 DCCP_SKB_CB(skb)->dccpd_ack_seq, 181 (unsigned long long) dreq->dreq_iss, 182 (unsigned long long) dreq->dreq_gss); 183 goto drop; 184 } 185 186 if (dccp_parse_options(sk, dreq, skb)) 187 goto drop; 188 189 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, 190 req, &own_req); 191 if (child) { 192 child = inet_csk_complete_hashdance(sk, child, req, own_req); 193 goto out; 194 } 195 196 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 197 drop: 198 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET) 199 req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 200 201 inet_csk_reqsk_queue_drop(sk, req); 202 out: 203 spin_unlock_bh(&dreq->dreq_lock); 204 return child; 205 } 206 207 EXPORT_SYMBOL_GPL(dccp_check_req); 208 209 /* 210 * Queue segment on the new socket if the new socket is active, 211 * otherwise we just shortcircuit this and continue with 212 * the new socket. 213 */ 214 int dccp_child_process(struct sock *parent, struct sock *child, 215 struct sk_buff *skb) 216 __releases(child) 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