net/ipv4/ipvs/ip_vs_sync.c

   1 /*
   2  * IPVS         An implementation of the IP virtual server support for the
   3  *              LINUX operating system.  IPVS is now implemented as a module
   4  *              over the NetFilter framework. IPVS can be used to build a
   5  *              high-performance and highly available server based on a
   6  *              cluster of servers.
   7  *
   8  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   9  *
  10  * ip_vs_sync:  sync connection info from master load balancer to backups
  11  *              through multicast
  12  *
  13  * Changes:
  14  *      Alexandre Cassen        :       Added master & backup support at a time.
  15  *      Alexandre Cassen        :       Added SyncID support for incoming sync
  16  *                                      messages filtering.
  17  *      Justin Ossevoort        :       Fix endian problem on sync message size.
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/inetdevice.h>
  23 #include <linux/net.h>
  24 #include <linux/completion.h>
  25 #include <linux/delay.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/in.h>
  28 #include <linux/igmp.h>                 /* for ip_mc_join_group */
  29 #include <linux/udp.h>
  30 #include <linux/err.h>
  31 #include <linux/kthread.h>
  32 #include <linux/wait.h>
  33
  34 #include <net/ip.h>
  35 #include <net/sock.h>
  36
  37 #include <net/ip_vs.h>
  38
  39 #define IP_VS_SYNC_GROUP 0xe0000051    /* multicast addr - 224.0.0.81 */
  40 #define IP_VS_SYNC_PORT  8848          /* multicast port */
  41
  42
  43 /*
  44  *      IPVS sync connection entry
  45  */
  46 struct ip_vs_sync_conn {
  47         __u8                    reserved;
  48
  49         /* Protocol, addresses and port numbers */
  50         __u8                    protocol;       /* Which protocol (TCP/UDP) */
  51         __be16                  cport;
  52         __be16                  vport;
  53         __be16                  dport;
  54         __be32                  caddr;          /* client address */
  55         __be32                  vaddr;          /* virtual address */
  56         __be32                  daddr;          /* destination address */
  57
  58         /* Flags and state transition */
  59         __be16                  flags;          /* status flags */
  60         __be16                  state;          /* state info */
  61
  62         /* The sequence options start here */
  63 };
  64
  65 struct ip_vs_sync_conn_options {
  66         struct ip_vs_seq        in_seq;         /* incoming seq. struct */
  67         struct ip_vs_seq        out_seq;        /* outgoing seq. struct */
  68 };
  69
  70 struct ip_vs_sync_thread_data {
  71         struct socket *sock;
  72         char *buf;
  73 };
  74
  75 #define SIMPLE_CONN_SIZE  (sizeof(struct ip_vs_sync_conn))
  76 #define FULL_CONN_SIZE  \
  77 (sizeof(struct ip_vs_sync_conn) + sizeof(struct ip_vs_sync_conn_options))
  78
  79
  80 /*
  81   The master mulitcasts messages to the backup load balancers in the
  82   following format.
  83
  84        0                   1                   2                   3
  85        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  86       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  87       |  Count Conns  |    SyncID     |            Size               |
  88       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  89       |                                                               |
  90       |                    IPVS Sync Connection (1)                   |
  91       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  92       |                            .                                  |
  93       |                            .                                  |
  94       |                            .                                  |
  95       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  96       |                                                               |
  97       |                    IPVS Sync Connection (n)                   |
  98       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  99 */
 100
 101 #define SYNC_MESG_HEADER_LEN    4
 102
 103 struct ip_vs_sync_mesg {
 104         __u8                    nr_conns;
 105         __u8                    syncid;
 106         __u16                   size;
 107
 108         /* ip_vs_sync_conn entries start here */
 109 };
 110
 111 /* the maximum length of sync (sending/receiving) message */
 112 static int sync_send_mesg_maxlen;
 113 static int sync_recv_mesg_maxlen;
 114
 115 struct ip_vs_sync_buff {
 116         struct list_head        list;
 117         unsigned long           firstuse;
 118
 119         /* pointers for the message data */
 120         struct ip_vs_sync_mesg  *mesg;
 121         unsigned char           *head;
 122         unsigned char           *end;
 123 };
 124
 125
 126 /* the sync_buff list head and the lock */
 127 static LIST_HEAD(ip_vs_sync_queue);
 128 static DEFINE_SPINLOCK(ip_vs_sync_lock);
 129
 130 /* current sync_buff for accepting new conn entries */
 131 static struct ip_vs_sync_buff   *curr_sb = NULL;
 132 static DEFINE_SPINLOCK(curr_sb_lock);
 133
 134 /* ipvs sync daemon state */
 135 volatile int ip_vs_sync_state = IP_VS_STATE_NONE;
 136 volatile int ip_vs_master_syncid = 0;
 137 volatile int ip_vs_backup_syncid = 0;
 138
 139 /* multicast interface name */
 140 char ip_vs_master_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 141 char ip_vs_backup_mcast_ifn[IP_VS_IFNAME_MAXLEN];
 142
 143 /* sync daemon tasks */
 144 static struct task_struct *sync_master_thread;
 145 static struct task_struct *sync_backup_thread;
 146
 147 /* multicast addr */
 148 static struct sockaddr_in mcast_addr = {
 149         .sin_family             = AF_INET,
 150         .sin_port               = __constant_htons(IP_VS_SYNC_PORT),
 151         .sin_addr.s_addr        = __constant_htonl(IP_VS_SYNC_GROUP),
 152 };
 153
 154
 155 static inline struct ip_vs_sync_buff *sb_dequeue(void)
 156 {
 157         struct ip_vs_sync_buff *sb;
 158
 159         spin_lock_bh(&ip_vs_sync_lock);
 160         if (list_empty(&ip_vs_sync_queue)) {
 161                 sb = NULL;
 162         } else {
 163                 sb = list_entry(ip_vs_sync_queue.next,
 164                                 struct ip_vs_sync_buff,
 165                                 list);
 166                 list_del(&sb->list);
 167         }
 168         spin_unlock_bh(&ip_vs_sync_lock);
 169
 170         return sb;
 171 }
 172
 173 static inline struct ip_vs_sync_buff * ip_vs_sync_buff_create(void)
 174 {
 175         struct ip_vs_sync_buff *sb;
 176
 177         if (!(sb=kmalloc(sizeof(struct ip_vs_sync_buff), GFP_ATOMIC)))
 178                 return NULL;
 179
 180         if (!(sb->mesg=kmalloc(sync_send_mesg_maxlen, GFP_ATOMIC))) {
 181                 kfree(sb);
 182                 return NULL;
 183         }
 184         sb->mesg->nr_conns = 0;
 185         sb->mesg->syncid = ip_vs_master_syncid;
 186         sb->mesg->size = 4;
 187         sb->head = (unsigned char *)sb->mesg + 4;
 188         sb->end = (unsigned char *)sb->mesg + sync_send_mesg_maxlen;
 189         sb->firstuse = jiffies;
 190         return sb;
 191 }
 192
 193 static inline void ip_vs_sync_buff_release(struct ip_vs_sync_buff *sb)
 194 {
 195         kfree(sb->mesg);
 196         kfree(sb);
 197 }
 198
 199 static inline void sb_queue_tail(struct ip_vs_sync_buff *sb)
 200 {
 201         spin_lock(&ip_vs_sync_lock);
 202         if (ip_vs_sync_state & IP_VS_STATE_MASTER)
 203                 list_add_tail(&sb->list, &ip_vs_sync_queue);
 204         else
 205                 ip_vs_sync_buff_release(sb);
 206         spin_unlock(&ip_vs_sync_lock);
 207 }
 208
 209 /*
 210  *      Get the current sync buffer if it has been created for more
 211  *      than the specified time or the specified time is zero.
 212  */
 213 static inline struct ip_vs_sync_buff *
 214 get_curr_sync_buff(unsigned long time)
 215 {
 216         struct ip_vs_sync_buff *sb;
 217
 218         spin_lock_bh(&curr_sb_lock);
 219         if (curr_sb && (time == 0 ||
 220                         time_before(jiffies - curr_sb->firstuse, time))) {
 221                 sb = curr_sb;
 222                 curr_sb = NULL;
 223         } else
 224                 sb = NULL;
 225         spin_unlock_bh(&curr_sb_lock);
 226         return sb;
 227 }
 228
 229
 230 /*
 231  *      Add an ip_vs_conn information into the current sync_buff.
 232  *      Called by ip_vs_in.
 233  */
 234 void ip_vs_sync_conn(struct ip_vs_conn *cp)
 235 {
 236         struct ip_vs_sync_mesg *m;
 237         struct ip_vs_sync_conn *s;
 238         int len;
 239
 240         spin_lock(&curr_sb_lock);
 241         if (!curr_sb) {
 242                 if (!(curr_sb=ip_vs_sync_buff_create())) {
 243                         spin_unlock(&curr_sb_lock);
 244                         IP_VS_ERR("ip_vs_sync_buff_create failed.\n");
 245                         return;
 246                 }
 247         }
 248
 249         len = (cp->flags & IP_VS_CONN_F_SEQ_MASK) ? FULL_CONN_SIZE :
 250                 SIMPLE_CONN_SIZE;
 251         m = curr_sb->mesg;
 252         s = (struct ip_vs_sync_conn *)curr_sb->head;
 253
 254         /* copy members */
 255         s->protocol = cp->protocol;
 256         s->cport = cp->cport;
 257         s->vport = cp->vport;
 258         s->dport = cp->dport;
 259         s->caddr = cp->caddr;
 260         s->vaddr = cp->vaddr;
 261         s->daddr = cp->daddr;
 262         s->flags = htons(cp->flags & ~IP_VS_CONN_F_HASHED);
 263         s->state = htons(cp->state);
 264         if (cp->flags & IP_VS_CONN_F_SEQ_MASK) {
 265                 struct ip_vs_sync_conn_options *opt =
 266                         (struct ip_vs_sync_conn_options *)&s[1];
 267                 memcpy(opt, &cp->in_seq, sizeof(*opt));
 268         }
 269
 270         m->nr_conns++;
 271         m->size += len;
 272         curr_sb->head += len;
 273
 274         /* check if there is a space for next one */
 275         if (curr_sb->head+FULL_CONN_SIZE > curr_sb->end) {
 276                 sb_queue_tail(curr_sb);
 277                 curr_sb = NULL;
 278         }
 279         spin_unlock(&curr_sb_lock);
 280
 281         /* synchronize its controller if it has */
 282         if (cp->control)
 283                 ip_vs_sync_conn(cp->control);
 284 }
 285
 286
 287 /*
 288  *      Process received multicast message and create the corresponding
 289  *      ip_vs_conn entries.
 290  */
 291 static void ip_vs_process_message(const char *buffer, const size_t buflen)
 292 {
 293         struct ip_vs_sync_mesg *m = (struct ip_vs_sync_mesg *)buffer;
 294         struct ip_vs_sync_conn *s;
 295         struct ip_vs_sync_conn_options *opt;
 296         struct ip_vs_conn *cp;
 297         struct ip_vs_protocol *pp;
 298         struct ip_vs_dest *dest;
 299         char *p;
 300         int i;
 301
 302         if (buflen < sizeof(struct ip_vs_sync_mesg)) {
 303                 IP_VS_ERR_RL("sync message header too short\n");
 304                 return;
 305         }
 306
 307         /* Convert size back to host byte order */
 308         m->size = ntohs(m->size);
 309
 310         if (buflen != m->size) {
 311                 IP_VS_ERR_RL("bogus sync message size\n");
 312                 return;
 313         }
 314
 315         /* SyncID sanity check */
 316         if (ip_vs_backup_syncid != 0 && m->syncid != ip_vs_backup_syncid) {
 317                 IP_VS_DBG(7, "Ignoring incoming msg with syncid = %d\n",
 318                           m->syncid);
 319                 return;
 320         }
 321
 322         p = (char *)buffer + sizeof(struct ip_vs_sync_mesg);
 323         for (i=0; i<m->nr_conns; i++) {
 324                 unsigned flags, state;
 325
 326                 if (p + SIMPLE_CONN_SIZE > buffer+buflen) {
 327                         IP_VS_ERR_RL("bogus conn in sync message\n");
 328                         return;
 329                 }
 330                 s = (struct ip_vs_sync_conn *) p;
 331                 flags = ntohs(s->flags) | IP_VS_CONN_F_SYNC;
 332                 flags &= ~IP_VS_CONN_F_HASHED;
 333                 if (flags & IP_VS_CONN_F_SEQ_MASK) {
 334                         opt = (struct ip_vs_sync_conn_options *)&s[1];
 335                         p += FULL_CONN_SIZE;
 336                         if (p > buffer+buflen) {
 337                                 IP_VS_ERR_RL("bogus conn options in sync message\n");
 338                                 return;
 339                         }
 340                 } else {
 341                         opt = NULL;
 342                         p += SIMPLE_CONN_SIZE;
 343                 }
 344
 345                 state = ntohs(s->state);
 346                 if (!(flags & IP_VS_CONN_F_TEMPLATE)) {
 347                         pp = ip_vs_proto_get(s->protocol);
 348                         if (!pp) {
 349                                 IP_VS_ERR_RL("Unsupported protocol %u in sync msg\n",
 350                                         s->protocol);
 351                                 continue;
 352                         }
 353                         if (state >= pp->num_states) {
 354                                 IP_VS_DBG(2, "Invalid %s state %u in sync msg\n",
 355                                         pp->name, state);
 356                                 continue;
 357                         }
 358                 } else {
 359                         /* protocol in templates is not used for state/timeout */
 360                         pp = NULL;
 361                         if (state > 0) {
 362                                 IP_VS_DBG(2, "Invalid template state %u in sync msg\n",
 363                                         state);
 364                                 state = 0;
 365                         }
 366                 }
 367
 368                 if (!(flags & IP_VS_CONN_F_TEMPLATE))
 369                         cp = ip_vs_conn_in_get(s->protocol,
 370                                                s->caddr, s->cport,
 371                                                s->vaddr, s->vport);
 372                 else
 373                         cp = ip_vs_ct_in_get(s->protocol,
 374                                                s->caddr, s->cport,
 375                                                s->vaddr, s->vport);
 376                 if (!cp) {
 377                         /*
 378                          * Find the appropriate destination for the connection.
 379                          * If it is not found the connection will remain unbound
 380                          * but still handled.
 381                          */
 382                         dest = ip_vs_find_dest(s->daddr, s->dport,
 383                                                s->vaddr, s->vport,
 384                                                s->protocol);
 385                         /*  Set the approprite ativity flag */
 386                         if (s->protocol == IPPROTO_TCP) {
 387                                 if (state != IP_VS_TCP_S_ESTABLISHED)
 388                                         flags |= IP_VS_CONN_F_INACTIVE;
 389                                 else
 390                                         flags &= ~IP_VS_CONN_F_INACTIVE;
 391                         }
 392                         cp = ip_vs_conn_new(s->protocol,
 393                                             s->caddr, s->cport,
 394                                             s->vaddr, s->vport,
 395                                             s->daddr, s->dport,
 396                                             flags, dest);
 397                         if (dest)
 398                                 atomic_dec(&dest->refcnt);
 399                         if (!cp) {
 400                                 IP_VS_ERR("ip_vs_conn_new failed\n");
 401                                 return;
 402                         }
 403                 } else if (!cp->dest) {
 404                         dest = ip_vs_try_bind_dest(cp);
 405                         if (dest)
 406                                 atomic_dec(&dest->refcnt);
 407                 } else if ((cp->dest) && (cp->protocol == IPPROTO_TCP) &&
 408                            (cp->state != state)) {
 409                         /* update active/inactive flag for the connection */
 410                         dest = cp->dest;
 411                         if (!(cp->flags & IP_VS_CONN_F_INACTIVE) &&
 412                                 (state != IP_VS_TCP_S_ESTABLISHED)) {
 413                                 atomic_dec(&dest->activeconns);
 414                                 atomic_inc(&dest->inactconns);
 415                                 cp->flags |= IP_VS_CONN_F_INACTIVE;
 416                         } else if ((cp->flags & IP_VS_CONN_F_INACTIVE) &&
 417                                 (state == IP_VS_TCP_S_ESTABLISHED)) {
 418                                 atomic_inc(&dest->activeconns);
 419                                 atomic_dec(&dest->inactconns);
 420                                 cp->flags &= ~IP_VS_CONN_F_INACTIVE;
 421                         }
 422                 }
 423
 424                 if (opt)
 425                         memcpy(&cp->in_seq, opt, sizeof(*opt));
 426                 atomic_set(&cp->in_pkts, sysctl_ip_vs_sync_threshold[0]);
 427                 cp->state = state;
 428                 cp->old_state = cp->state;
 429                 /*
 430                  * We can not recover the right timeout for templates
 431                  * in all cases, we can not find the right fwmark
 432                  * virtual service. If needed, we can do it for
 433                  * non-fwmark persistent services.
 434                  */
 435                 if (!(flags & IP_VS_CONN_F_TEMPLATE) && pp->timeout_table)
 436                         cp->timeout = pp->timeout_table[state];
 437                 else
 438                         cp->timeout = (3*60*HZ);
 439                 ip_vs_conn_put(cp);
 440         }
 441 }
 442
 443
 444 /*
 445  *      Setup loopback of outgoing multicasts on a sending socket
 446  */
 447 static void set_mcast_loop(struct sock *sk, u_char loop)
 448 {
 449         struct inet_sock *inet = inet_sk(sk);
 450
 451         /* setsockopt(sock, SOL_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); */
 452         lock_sock(sk);
 453         inet->mc_loop = loop ? 1 : 0;
 454         release_sock(sk);
 455 }
 456
 457 /*
 458  *      Specify TTL for outgoing multicasts on a sending socket
 459  */
 460 static void set_mcast_ttl(struct sock *sk, u_char ttl)
 461 {
 462         struct inet_sock *inet = inet_sk(sk);
 463
 464         /* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
 465         lock_sock(sk);
 466         inet->mc_ttl = ttl;
 467         release_sock(sk);
 468 }
 469
 470 /*
 471  *      Specifiy default interface for outgoing multicasts
 472  */
 473 static int set_mcast_if(struct sock *sk, char *ifname)
 474 {
 475         struct net_device *dev;
 476         struct inet_sock *inet = inet_sk(sk);
 477
 478         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 479                 return -ENODEV;
 480
 481         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 482                 return -EINVAL;
 483
 484         lock_sock(sk);
 485         inet->mc_index = dev->ifindex;
 486         /*  inet->mc_addr  = 0; */
 487         release_sock(sk);
 488
 489         return 0;
 490 }
 491
 492
 493 /*
 494  *      Set the maximum length of sync message according to the
 495  *      specified interface's MTU.
 496  */
 497 static int set_sync_mesg_maxlen(int sync_state)
 498 {
 499         struct net_device *dev;
 500         int num;
 501
 502         if (sync_state == IP_VS_STATE_MASTER) {
 503                 if ((dev = __dev_get_by_name(&init_net, ip_vs_master_mcast_ifn)) == NULL)
 504                         return -ENODEV;
 505
 506                 num = (dev->mtu - sizeof(struct iphdr) -
 507                        sizeof(struct udphdr) -
 508                        SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
 509                 sync_send_mesg_maxlen =
 510                         SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
 511                 IP_VS_DBG(7, "setting the maximum length of sync sending "
 512                           "message %d.\n", sync_send_mesg_maxlen);
 513         } else if (sync_state == IP_VS_STATE_BACKUP) {
 514                 if ((dev = __dev_get_by_name(&init_net, ip_vs_backup_mcast_ifn)) == NULL)
 515                         return -ENODEV;
 516
 517                 sync_recv_mesg_maxlen = dev->mtu -
 518                         sizeof(struct iphdr) - sizeof(struct udphdr);
 519                 IP_VS_DBG(7, "setting the maximum length of sync receiving "
 520                           "message %d.\n", sync_recv_mesg_maxlen);
 521         }
 522
 523         return 0;
 524 }
 525
 526
 527 /*
 528  *      Join a multicast group.
 529  *      the group is specified by a class D multicast address 224.0.0.0/8
 530  *      in the in_addr structure passed in as a parameter.
 531  */
 532 static int
 533 join_mcast_group(struct sock *sk, struct in_addr *addr, char *ifname)
 534 {
 535         struct ip_mreqn mreq;
 536         struct net_device *dev;
 537         int ret;
 538
 539         memset(&mreq, 0, sizeof(mreq));
 540         memcpy(&mreq.imr_multiaddr, addr, sizeof(struct in_addr));
 541
 542         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 543                 return -ENODEV;
 544         if (sk->sk_bound_dev_if && dev->ifindex != sk->sk_bound_dev_if)
 545                 return -EINVAL;
 546
 547         mreq.imr_ifindex = dev->ifindex;
 548
 549         lock_sock(sk);
 550         ret = ip_mc_join_group(sk, &mreq);
 551         release_sock(sk);
 552
 553         return ret;
 554 }
 555
 556
 557 static int bind_mcastif_addr(struct socket *sock, char *ifname)
 558 {
 559         struct net_device *dev;
 560         __be32 addr;
 561         struct sockaddr_in sin;
 562
 563         if ((dev = __dev_get_by_name(&init_net, ifname)) == NULL)
 564                 return -ENODEV;
 565
 566         addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
 567         if (!addr)
 568                 IP_VS_ERR("You probably need to specify IP address on "
 569                           "multicast interface.\n");
 570
 571         IP_VS_DBG(7, "binding socket with (%s) %u.%u.%u.%u\n",
 572                   ifname, NIPQUAD(addr));
 573
 574         /* Now bind the socket with the address of multicast interface */
 575         sin.sin_family       = AF_INET;
 576         sin.sin_addr.s_addr  = addr;
 577         sin.sin_port         = 0;
 578
 579         return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
 580 }
 581
 582 /*
 583  *      Set up sending multicast socket over UDP
 584  */
 585 static struct socket * make_send_sock(void)
 586 {
 587         struct socket *sock;
 588         int result;
 589
 590         /* First create a socket */
 591         result = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock);
 592         if (result < 0) {
 593                 IP_VS_ERR("Error during creation of socket; terminating\n");
 594                 return ERR_PTR(result);
 595         }
 596
 597         result = set_mcast_if(sock->sk, ip_vs_master_mcast_ifn);
 598         if (result < 0) {
 599                 IP_VS_ERR("Error setting outbound mcast interface\n");
 600                 goto error;
 601         }
 602
 603         set_mcast_loop(sock->sk, 0);
 604         set_mcast_ttl(sock->sk, 1);
 605
 606         result = bind_mcastif_addr(sock, ip_vs_master_mcast_ifn);
 607         if (result < 0) {
 608                 IP_VS_ERR("Error binding address of the mcast interface\n");
 609                 goto error;
 610         }
 611
 612         result = sock->ops->connect(sock, (struct sockaddr *) &mcast_addr,
 613                         sizeof(struct sockaddr), 0);
 614         if (result < 0) {
 615                 IP_VS_ERR("Error connecting to the multicast addr\n");
 616                 goto error;
 617         }
 618
 619         return sock;
 620
 621   error:
 622         sock_release(sock);
 623         return ERR_PTR(result);
 624 }
 625
 626
 627 /*
 628  *      Set up receiving multicast socket over UDP
 629  */
 630 static struct socket * make_receive_sock(void)
 631 {
 632         struct socket *sock;
 633         int result;
 634
 635         /* First create a socket */
 636         result = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock);
 637         if (result < 0) {
 638                 IP_VS_ERR("Error during creation of socket; terminating\n");
 639                 return ERR_PTR(result);
 640         }
 641
 642         /* it is equivalent to the REUSEADDR option in user-space */
 643         sock->sk->sk_reuse = 1;
 644
 645         result = sock->ops->bind(sock, (struct sockaddr *) &mcast_addr,
 646                         sizeof(struct sockaddr));
 647         if (result < 0) {
 648                 IP_VS_ERR("Error binding to the multicast addr\n");
 649                 goto error;
 650         }
 651
 652         /* join the multicast group */
 653         result = join_mcast_group(sock->sk,
 654                         (struct in_addr *) &mcast_addr.sin_addr,
 655                         ip_vs_backup_mcast_ifn);
 656         if (result < 0) {
 657                 IP_VS_ERR("Error joining to the multicast group\n");
 658                 goto error;
 659         }
 660
 661         return sock;
 662
 663   error:
 664         sock_release(sock);
 665         return ERR_PTR(result);
 666 }
 667
 668
 669 static int
 670 ip_vs_send_async(struct socket *sock, const char *buffer, const size_t length)
 671 {
 672         struct msghdr   msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
 673         struct kvec     iov;
 674         int             len;
 675
 676         EnterFunction(7);
 677         iov.iov_base     = (void *)buffer;
 678         iov.iov_len      = length;
 679
 680         len = kernel_sendmsg(sock, &msg, &iov, 1, (size_t)(length));
 681
 682         LeaveFunction(7);
 683         return len;
 684 }
 685
 686 static void
 687 ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_mesg *msg)
 688 {
 689         int msize;
 690
 691         msize = msg->size;
 692
 693         /* Put size in network byte order */
 694         msg->size = htons(msg->size);
 695
 696         if (ip_vs_send_async(sock, (char *)msg, msize) != msize)
 697                 IP_VS_ERR("ip_vs_send_async error\n");
 698 }
 699
 700 static int
 701 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
 702 {
 703         struct msghdr           msg = {NULL,};
 704         struct kvec             iov;
 705         int                     len;
 706
 707         EnterFunction(7);
 708
 709         /* Receive a packet */
 710         iov.iov_base     = buffer;
 711         iov.iov_len      = (size_t)buflen;
 712
 713         len = kernel_recvmsg(sock, &msg, &iov, 1, buflen, 0);
 714
 715         if (len < 0)
 716                 return -1;
 717
 718         LeaveFunction(7);
 719         return len;
 720 }
 721
 722
 723 static int sync_thread_master(void *data)
 724 {
 725         struct ip_vs_sync_thread_data *tinfo = data;
 726         struct ip_vs_sync_buff *sb;
 727
 728         IP_VS_INFO("sync thread started: state = MASTER, mcast_ifn = %s, "
 729                    "syncid = %d\n",
 730                    ip_vs_master_mcast_ifn, ip_vs_master_syncid);
 731
 732         while (!kthread_should_stop()) {
 733                 while ((sb = sb_dequeue())) {
 734                         ip_vs_send_sync_msg(tinfo->sock, sb->mesg);
 735                         ip_vs_sync_buff_release(sb);
 736                 }
 737
 738                 /* check if entries stay in curr_sb for 2 seconds */
 739                 sb = get_curr_sync_buff(2 * HZ);
 740                 if (sb) {
 741                         ip_vs_send_sync_msg(tinfo->sock, sb->mesg);
 742                         ip_vs_sync_buff_release(sb);
 743                 }
 744
 745                 schedule_timeout_interruptible(HZ);
 746         }
 747
 748         /* clean up the sync_buff queue */
 749         while ((sb=sb_dequeue())) {
 750                 ip_vs_sync_buff_release(sb);
 751         }
 752
 753         /* clean up the current sync_buff */
 754         if ((sb = get_curr_sync_buff(0))) {
 755                 ip_vs_sync_buff_release(sb);
 756         }
 757
 758         /* release the sending multicast socket */
 759         sock_release(tinfo->sock);
 760         kfree(tinfo);
 761
 762         return 0;
 763 }
 764
 765
 766 static int sync_thread_backup(void *data)
 767 {
 768         struct ip_vs_sync_thread_data *tinfo = data;
 769         int len;
 770
 771         IP_VS_INFO("sync thread started: state = BACKUP, mcast_ifn = %s, "
 772                    "syncid = %d\n",
 773                    ip_vs_backup_mcast_ifn, ip_vs_backup_syncid);
 774
 775         while (!kthread_should_stop()) {
 776                 wait_event_interruptible(*tinfo->sock->sk->sk_sleep,
 777                          !skb_queue_empty(&tinfo->sock->sk->sk_receive_queue)
 778                          || kthread_should_stop());
 779
 780                 /* do we have data now? */
 781                 while (!skb_queue_empty(&(tinfo->sock->sk->sk_receive_queue))) {
 782                         len = ip_vs_receive(tinfo->sock, tinfo->buf,
 783                                         sync_recv_mesg_maxlen);
 784                         if (len <= 0) {
 785                                 IP_VS_ERR("receiving message error\n");
 786                                 break;
 787                         }
 788
 789                         /* disable bottom half, because it accesses the data
 790                            shared by softirq while getting/creating conns */
 791                         local_bh_disable();
 792                         ip_vs_process_message(tinfo->buf, len);
 793                         local_bh_enable();
 794                 }
 795         }
 796
 797         /* release the sending multicast socket */
 798         sock_release(tinfo->sock);
 799         kfree(tinfo->buf);
 800         kfree(tinfo);
 801
 802         return 0;
 803 }
 804
 805
 806 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 807 {
 808         struct ip_vs_sync_thread_data *tinfo;
 809         struct task_struct **realtask, *task;
 810         struct socket *sock;
 811         char *name, *buf = NULL;
 812         int (*threadfn)(void *data);
 813         int result = -ENOMEM;
 814
 815         IP_VS_DBG(7, "%s: pid %d\n", __func__, task_pid_nr(current));
 816         IP_VS_DBG(7, "Each ip_vs_sync_conn entry needs %Zd bytes\n",
 817                   sizeof(struct ip_vs_sync_conn));
 818
 819         if (state == IP_VS_STATE_MASTER) {
 820                 if (sync_master_thread)
 821                         return -EEXIST;
 822
 823                 strlcpy(ip_vs_master_mcast_ifn, mcast_ifn,
 824                         sizeof(ip_vs_master_mcast_ifn));
 825                 ip_vs_master_syncid = syncid;
 826                 realtask = &sync_master_thread;
 827                 name = "ipvs_syncmaster";
 828                 threadfn = sync_thread_master;
 829                 sock = make_send_sock();
 830         } else if (state == IP_VS_STATE_BACKUP) {
 831                 if (sync_backup_thread)
 832                         return -EEXIST;
 833
 834                 strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn,
 835                         sizeof(ip_vs_backup_mcast_ifn));
 836                 ip_vs_backup_syncid = syncid;
 837                 realtask = &sync_backup_thread;
 838                 name = "ipvs_syncbackup";
 839                 threadfn = sync_thread_backup;
 840                 sock = make_receive_sock();
 841         } else {
 842                 return -EINVAL;
 843         }
 844
 845         if (IS_ERR(sock)) {
 846                 result = PTR_ERR(sock);
 847                 goto out;
 848         }
 849
 850         set_sync_mesg_maxlen(state);
 851         if (state == IP_VS_STATE_BACKUP) {
 852                 buf = kmalloc(sync_recv_mesg_maxlen, GFP_KERNEL);
 853                 if (!buf)
 854                         goto outsocket;
 855         }
 856
 857         tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL);
 858         if (!tinfo)
 859                 goto outbuf;
 860
 861         tinfo->sock = sock;
 862         tinfo->buf = buf;
 863
 864         task = kthread_run(threadfn, tinfo, name);
 865         if (IS_ERR(task)) {
 866                 result = PTR_ERR(task);
 867                 goto outtinfo;
 868         }
 869
 870         /* mark as active */
 871         *realtask = task;
 872         ip_vs_sync_state |= state;
 873
 874         /* increase the module use count */
 875         ip_vs_use_count_inc();
 876
 877         return 0;
 878
 879 outtinfo:
 880         kfree(tinfo);
 881 outbuf:
 882         kfree(buf);
 883 outsocket:
 884         sock_release(sock);
 885 out:
 886         return result;
 887 }
 888
 889
 890 int stop_sync_thread(int state)
 891 {
 892         IP_VS_DBG(7, "%s: pid %d\n", __func__, task_pid_nr(current));
 893
 894         if (state == IP_VS_STATE_MASTER) {
 895                 if (!sync_master_thread)
 896                         return -ESRCH;
 897
 898                 IP_VS_INFO("stopping master sync thread %d ...\n",
 899                            task_pid_nr(sync_master_thread));
 900
 901                 /*
 902                  * The lock synchronizes with sb_queue_tail(), so that we don't
 903                  * add sync buffers to the queue, when we are already in
 904                  * progress of stopping the master sync daemon.
 905                  */
 906
 907                 spin_lock(&ip_vs_sync_lock);
 908                 ip_vs_sync_state &= ~IP_VS_STATE_MASTER;
 909                 spin_unlock(&ip_vs_sync_lock);
 910                 kthread_stop(sync_master_thread);
 911                 sync_master_thread = NULL;
 912         } else if (state == IP_VS_STATE_BACKUP) {
 913                 if (!sync_backup_thread)
 914                         return -ESRCH;
 915
 916                 IP_VS_INFO("stopping backup sync thread %d ...\n",
 917                            task_pid_nr(sync_backup_thread));
 918
 919                 ip_vs_sync_state &= ~IP_VS_STATE_BACKUP;
 920                 kthread_stop(sync_backup_thread);
 921                 sync_backup_thread = NULL;
 922         } else {
 923                 return -EINVAL;
 924         }
 925
 926         /* decrease the module use count */
 927         ip_vs_use_count_dec();
 928
 929         return 0;
 930 }