net/rds/tcp_listen.c

   1 /*
   2  * Copyright (c) 2006, 2018 Oracle.  All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  *
  32  */
  33 #include <linux/kernel.h>
  34 #include <linux/gfp.h>
  35 #include <linux/in.h>
  36 #include <net/tcp.h>
  37
  38 #include "rds.h"
  39 #include "tcp.h"
  40
  41 int rds_tcp_keepalive(struct socket *sock)
  42 {
  43         /* values below based on xs_udp_default_timeout */
  44         int keepidle = 5; /* send a probe 'keepidle' secs after last data */
  45         int keepcnt = 5; /* number of unack'ed probes before declaring dead */
  46         int keepalive = 1;
  47         int ret = 0;
  48
  49         ret = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
  50                                 (char *)&keepalive, sizeof(keepalive));
  51         if (ret < 0)
  52                 goto bail;
  53
  54         ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT,
  55                                 (char *)&keepcnt, sizeof(keepcnt));
  56         if (ret < 0)
  57                 goto bail;
  58
  59         ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE,
  60                                 (char *)&keepidle, sizeof(keepidle));
  61         if (ret < 0)
  62                 goto bail;
  63
  64         /* KEEPINTVL is the interval between successive probes. We follow
  65          * the model in xs_tcp_finish_connecting() and re-use keepidle.
  66          */
  67         ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL,
  68                                 (char *)&keepidle, sizeof(keepidle));
  69 bail:
  70         return ret;
  71 }
  72
  73 /* rds_tcp_accept_one_path(): if accepting on cp_index > 0, make sure the
  74  * client's ipaddr < server's ipaddr. Otherwise, close the accepted
  75  * socket and force a reconneect from smaller -> larger ip addr. The reason
  76  * we special case cp_index 0 is to allow the rds probe ping itself to itself
  77  * get through efficiently.
  78  * Since reconnects are only initiated from the node with the numerically
  79  * smaller ip address, we recycle conns in RDS_CONN_ERROR on the passive side
  80  * by moving them to CONNECTING in this function.
  81  */
  82 static
  83 struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
  84 {
  85         int i;
  86         bool peer_is_smaller = IS_CANONICAL(conn->c_faddr, conn->c_laddr);
  87         int npaths = max_t(int, 1, conn->c_npaths);
  88
  89         /* for mprds, all paths MUST be initiated by the peer
  90          * with the smaller address.
  91          */
  92         if (!peer_is_smaller) {
  93                 /* Make sure we initiate at least one path if this
  94                  * has not already been done; rds_start_mprds() will
  95                  * take care of additional paths, if necessary.
  96                  */
  97                 if (npaths == 1)
  98                         rds_conn_path_connect_if_down(&conn->c_path[0]);
  99                 return NULL;
 100         }
 101
 102         for (i = 0; i < npaths; i++) {
 103                 struct rds_conn_path *cp = &conn->c_path[i];
 104
 105                 if (rds_conn_path_transition(cp, RDS_CONN_DOWN,
 106                                              RDS_CONN_CONNECTING) ||
 107                     rds_conn_path_transition(cp, RDS_CONN_ERROR,
 108                                              RDS_CONN_CONNECTING)) {
 109                         return cp->cp_transport_data;
 110                 }
 111         }
 112         return NULL;
 113 }
 114
 115 void rds_tcp_set_linger(struct socket *sock)
 116 {
 117         struct linger no_linger = {
 118                 .l_onoff = 1,
 119                 .l_linger = 0,
 120         };
 121
 122         kernel_setsockopt(sock, SOL_SOCKET, SO_LINGER,
 123                           (char *)&no_linger, sizeof(no_linger));
 124 }
 125
 126 int rds_tcp_accept_one(struct socket *sock)
 127 {
 128         struct socket *new_sock = NULL;
 129         struct rds_connection *conn;
 130         int ret;
 131         struct inet_sock *inet;
 132         struct rds_tcp_connection *rs_tcp = NULL;
 133         int conn_state;
 134         struct rds_conn_path *cp;
 135
 136         if (!sock) /* module unload or netns delete in progress */
 137                 return -ENETUNREACH;
 138
 139         ret = sock_create_lite(sock->sk->sk_family,
 140                                sock->sk->sk_type, sock->sk->sk_protocol,
 141                                &new_sock);
 142         if (ret)
 143                 goto out;
 144
 145         ret = sock->ops->accept(sock, new_sock, O_NONBLOCK, true);
 146         if (ret < 0)
 147                 goto out;
 148
 149         /* sock_create_lite() does not get a hold on the owner module so we
 150          * need to do it here.  Note that sock_release() uses sock->ops to
 151          * determine if it needs to decrement the reference count.  So set
 152          * sock->ops after calling accept() in case that fails.  And there's
 153          * no need to do try_module_get() as the listener should have a hold
 154          * already.
 155          */
 156         new_sock->ops = sock->ops;
 157         __module_get(new_sock->ops->owner);
 158
 159         ret = rds_tcp_keepalive(new_sock);
 160         if (ret < 0)
 161                 goto out;
 162
 163         rds_tcp_tune(new_sock);
 164
 165         inet = inet_sk(new_sock->sk);
 166
 167         rdsdebug("accepted tcp %pI4:%u -> %pI4:%u\n",
 168                  &inet->inet_saddr, ntohs(inet->inet_sport),
 169                  &inet->inet_daddr, ntohs(inet->inet_dport));
 170
 171         conn = rds_conn_create(sock_net(sock->sk),
 172                                inet->inet_saddr, inet->inet_daddr,
 173                                &rds_tcp_transport, GFP_KERNEL);
 174         if (IS_ERR(conn)) {
 175                 ret = PTR_ERR(conn);
 176                 goto out;
 177         }
 178         /* An incoming SYN request came in, and TCP just accepted it.
 179          *
 180          * If the client reboots, this conn will need to be cleaned up.
 181          * rds_tcp_state_change() will do that cleanup
 182          */
 183         rs_tcp = rds_tcp_accept_one_path(conn);
 184         if (!rs_tcp)
 185                 goto rst_nsk;
 186         mutex_lock(&rs_tcp->t_conn_path_lock);
 187         cp = rs_tcp->t_cpath;
 188         conn_state = rds_conn_path_state(cp);
 189         WARN_ON(conn_state == RDS_CONN_UP);
 190         if (conn_state != RDS_CONN_CONNECTING && conn_state != RDS_CONN_ERROR)
 191                 goto rst_nsk;
 192         if (rs_tcp->t_sock) {
 193                 /* Duelling SYN has been handled in rds_tcp_accept_one() */
 194                 rds_tcp_reset_callbacks(new_sock, cp);
 195                 /* rds_connect_path_complete() marks RDS_CONN_UP */
 196                 rds_connect_path_complete(cp, RDS_CONN_RESETTING);
 197         } else {
 198                 rds_tcp_set_callbacks(new_sock, cp);
 199                 rds_connect_path_complete(cp, RDS_CONN_CONNECTING);
 200         }
 201         new_sock = NULL;
 202         ret = 0;
 203         if (conn->c_npaths == 0)
 204                 rds_send_ping(cp->cp_conn, cp->cp_index);
 205         goto out;
 206 rst_nsk:
 207         /* reset the newly returned accept sock and bail.
 208          * It is safe to set linger on new_sock because the RDS connection
 209          * has not been brought up on new_sock, so no RDS-level data could
 210          * be pending on it. By setting linger, we achieve the side-effect
 211          * of avoiding TIME_WAIT state on new_sock.
 212          */
 213         rds_tcp_set_linger(new_sock);
 214         kernel_sock_shutdown(new_sock, SHUT_RDWR);
 215         ret = 0;
 216 out:
 217         if (rs_tcp)
 218                 mutex_unlock(&rs_tcp->t_conn_path_lock);
 219         if (new_sock)
 220                 sock_release(new_sock);
 221         return ret;
 222 }
 223
 224 void rds_tcp_listen_data_ready(struct sock *sk)
 225 {
 226         void (*ready)(struct sock *sk);
 227
 228         rdsdebug("listen data ready sk %p\n", sk);
 229
 230         read_lock_bh(&sk->sk_callback_lock);
 231         ready = sk->sk_user_data;
 232         if (!ready) { /* check for teardown race */
 233                 ready = sk->sk_data_ready;
 234                 goto out;
 235         }
 236
 237         /*
 238          * ->sk_data_ready is also called for a newly established child socket
 239          * before it has been accepted and the accepter has set up their
 240          * data_ready.. we only want to queue listen work for our listening
 241          * socket
 242          *
 243          * (*ready)() may be null if we are racing with netns delete, and
 244          * the listen socket is being torn down.
 245          */
 246         if (sk->sk_state == TCP_LISTEN)
 247                 rds_tcp_accept_work(sk);
 248         else
 249                 ready = rds_tcp_listen_sock_def_readable(sock_net(sk));
 250
 251 out:
 252         read_unlock_bh(&sk->sk_callback_lock);
 253         if (ready)
 254                 ready(sk);
 255 }
 256
 257 struct socket *rds_tcp_listen_init(struct net *net)
 258 {
 259         struct sockaddr_in sin;
 260         struct socket *sock = NULL;
 261         int ret;
 262
 263         ret = sock_create_kern(net, PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
 264         if (ret < 0)
 265                 goto out;
 266
 267         sock->sk->sk_reuse = SK_CAN_REUSE;
 268         rds_tcp_nonagle(sock);
 269
 270         write_lock_bh(&sock->sk->sk_callback_lock);
 271         sock->sk->sk_user_data = sock->sk->sk_data_ready;
 272         sock->sk->sk_data_ready = rds_tcp_listen_data_ready;
 273         write_unlock_bh(&sock->sk->sk_callback_lock);
 274
 275         sin.sin_family = PF_INET;
 276         sin.sin_addr.s_addr = (__force u32)htonl(INADDR_ANY);
 277         sin.sin_port = (__force u16)htons(RDS_TCP_PORT);
 278
 279         ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
 280         if (ret < 0)
 281                 goto out;
 282
 283         ret = sock->ops->listen(sock, 64);
 284         if (ret < 0)
 285                 goto out;
 286
 287         return sock;
 288 out:
 289         if (sock)
 290                 sock_release(sock);
 291         return NULL;
 292 }
 293
 294 void rds_tcp_listen_stop(struct socket *sock, struct work_struct *acceptor)
 295 {
 296         struct sock *sk;
 297
 298         if (!sock)
 299                 return;
 300
 301         sk = sock->sk;
 302
 303         /* serialize with and prevent further callbacks */
 304         lock_sock(sk);
 305         write_lock_bh(&sk->sk_callback_lock);
 306         if (sk->sk_user_data) {
 307                 sk->sk_data_ready = sk->sk_user_data;
 308                 sk->sk_user_data = NULL;
 309         }
 310         write_unlock_bh(&sk->sk_callback_lock);
 311         release_sock(sk);
 312
 313         /* wait for accepts to stop and close the socket */
 314         flush_workqueue(rds_wq);
 315         flush_work(acceptor);
 316         sock_release(sock);
 317 }