net/filter-rewriter.c

   1 /*
   2  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
   3  * Copyright (c) 2016 FUJITSU LIMITED
   4  * Copyright (c) 2016 Intel Corporation
   5  *
   6  * Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2 or
   9  * later.  See the COPYING file in the top-level directory.
  10  */
  11
  12 #include "qemu/osdep.h"
  13 #include "trace.h"
  14 #include "colo.h"
  15 #include "net/filter.h"
  16 #include "net/net.h"
  17 #include "qemu/error-report.h"
  18 #include "qom/object.h"
  19 #include "qemu/main-loop.h"
  20 #include "qemu/iov.h"
  21 #include "net/checksum.h"
  22 #include "net/colo.h"
  23 #include "migration/colo.h"
  24 #include "util.h"
  25
  26 #define TYPE_FILTER_REWRITER "filter-rewriter"
  27 OBJECT_DECLARE_SIMPLE_TYPE(RewriterState, FILTER_REWRITER)
  28
  29 #define FAILOVER_MODE_ON  true
  30 #define FAILOVER_MODE_OFF false
  31
  32 struct RewriterState {
  33     NetFilterState parent_obj;
  34     NetQueue *incoming_queue;
  35     /* hashtable to save connection */
  36     GHashTable *connection_track_table;
  37     bool vnet_hdr;
  38     bool failover_mode;
  39 };
  40
  41 static void filter_rewriter_failover_mode(RewriterState *s)
  42 {
  43     s->failover_mode = FAILOVER_MODE_ON;
  44 }
  45
  46 static void filter_rewriter_flush(NetFilterState *nf)
  47 {
  48     RewriterState *s = FILTER_REWRITER(nf);
  49
  50     if (!qemu_net_queue_flush(s->incoming_queue)) {
  51         /* Unable to empty the queue, purge remaining packets */
  52         qemu_net_queue_purge(s->incoming_queue, nf->netdev);
  53     }
  54 }
  55
  56 /*
  57  * Return 1 on success, if return 0 means the pkt
  58  * is not TCP packet
  59  */
  60 static int is_tcp_packet(Packet *pkt)
  61 {
  62     if (!parse_packet_early(pkt) &&
  63         pkt->ip->ip_p == IPPROTO_TCP) {
  64         return 1;
  65     } else {
  66         return 0;
  67     }
  68 }
  69
  70 /* handle tcp packet from primary guest */
  71 static int handle_primary_tcp_pkt(RewriterState *rf,
  72                                   Connection *conn,
  73                                   Packet *pkt, ConnectionKey *key)
  74 {
  75     struct tcp_hdr *tcp_pkt;
  76
  77     tcp_pkt = (struct tcp_hdr *)pkt->transport_header;
  78     if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO)) {
  79         trace_colo_filter_rewriter_pkt_info(__func__,
  80                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
  81                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
  82                     tcp_pkt->th_flags);
  83     }
  84     if (trace_event_get_state_backends(
  85           TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) {
  86         trace_colo_filter_rewriter_conn_offset(conn->offset);
  87     }
  88
  89     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN)) &&
  90         conn->tcp_state == TCPS_SYN_SENT) {
  91         conn->tcp_state = TCPS_ESTABLISHED;
  92     }
  93
  94     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
  95         /*
  96          * we use this flag update offset func
  97          * run once in independent tcp connection
  98          */
  99         conn->tcp_state = TCPS_SYN_RECEIVED;
 100     }
 101
 102     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
 103         if (conn->tcp_state == TCPS_SYN_RECEIVED) {
 104             /*
 105              * offset = secondary_seq - primary seq
 106              * ack packet sent by guest from primary node,
 107              * so we use th_ack - 1 get primary_seq
 108              */
 109             conn->offset -= (ntohl(tcp_pkt->th_ack) - 1);
 110             conn->tcp_state = TCPS_ESTABLISHED;
 111         }
 112         if (conn->offset) {
 113             /* handle packets to the secondary from the primary */
 114             tcp_pkt->th_ack = htonl(ntohl(tcp_pkt->th_ack) + conn->offset);
 115
 116             net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
 117                                    pkt->size - pkt->vnet_hdr_len, CSUM_TCP);
 118         }
 119
 120         /*
 121          * Passive close step 3
 122          */
 123         if ((conn->tcp_state == TCPS_LAST_ACK) &&
 124             (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
 125             conn->tcp_state = TCPS_CLOSED;
 126             g_hash_table_remove(rf->connection_track_table, key);
 127         }
 128     }
 129
 130     if ((tcp_pkt->th_flags & TH_FIN) == TH_FIN) {
 131         /*
 132          * Passive close.
 133          * Step 1:
 134          * The *server* side of this connect is VM, *client* tries to close
 135          * the connection. We will into CLOSE_WAIT status.
 136          *
 137          * Step 2:
 138          * In this step we will into LAST_ACK status.
 139          *
 140          * We got 'fin=1, ack=1' packet from server side, we need to
 141          * record the seq of 'fin=1, ack=1' packet.
 142          *
 143          * Step 3:
 144          * We got 'ack=1' packets from client side, it acks 'fin=1, ack=1'
 145          * packet from server side. From this point, we can ensure that there
 146          * will be no packets in the connection, except that, some errors
 147          * happen between the path of 'filter object' and vNIC, if this rare
 148          * case really happen, we can still create a new connection,
 149          * So it is safe to remove the connection from connection_track_table.
 150          *
 151          */
 152         if (conn->tcp_state == TCPS_ESTABLISHED) {
 153             conn->tcp_state = TCPS_CLOSE_WAIT;
 154         }
 155
 156         /*
 157          * Active close step 2.
 158          */
 159         if (conn->tcp_state == TCPS_FIN_WAIT_1) {
 160             /*
 161              * For simplify implementation, we needn't wait 2MSL time
 162              * in filter rewriter. Because guest kernel will track the
 163              * TCP status and wait 2MSL time, if client resend the FIN
 164              * packet, guest will apply the last ACK too.
 165              * So, we skip the TCPS_TIME_WAIT state here and go straight
 166              * to TCPS_CLOSED state.
 167              */
 168             conn->tcp_state = TCPS_CLOSED;
 169             g_hash_table_remove(rf->connection_track_table, key);
 170         }
 171     }
 172
 173     return 0;
 174 }
 175
 176 /* handle tcp packet from secondary guest */
 177 static int handle_secondary_tcp_pkt(RewriterState *rf,
 178                                     Connection *conn,
 179                                     Packet *pkt, ConnectionKey *key)
 180 {
 181     struct tcp_hdr *tcp_pkt;
 182
 183     tcp_pkt = (struct tcp_hdr *)pkt->transport_header;
 184
 185     if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO)) {
 186         trace_colo_filter_rewriter_pkt_info(__func__,
 187                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
 188                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
 189                     tcp_pkt->th_flags);
 190     }
 191     if (trace_event_get_state_backends(
 192           TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) {
 193         trace_colo_filter_rewriter_conn_offset(conn->offset);
 194     }
 195
 196     if (conn->tcp_state == TCPS_SYN_RECEIVED &&
 197         ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
 198         /*
 199          * save offset = secondary_seq and then
 200          * in handle_primary_tcp_pkt make offset
 201          * = secondary_seq - primary_seq
 202          */
 203         conn->offset = ntohl(tcp_pkt->th_seq);
 204     }
 205
 206     /* VM active connect */
 207     if (conn->tcp_state == TCPS_CLOSED &&
 208         ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
 209         conn->tcp_state = TCPS_SYN_SENT;
 210     }
 211
 212     if ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK) {
 213         /* Only need to adjust seq while offset is Non-zero */
 214         if (conn->offset) {
 215             /* handle packets to the primary from the secondary*/
 216             tcp_pkt->th_seq = htonl(ntohl(tcp_pkt->th_seq) - conn->offset);
 217
 218             net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
 219                                    pkt->size - pkt->vnet_hdr_len, CSUM_TCP);
 220         }
 221     }
 222
 223     /*
 224      * Passive close step 2:
 225      */
 226     if (conn->tcp_state == TCPS_CLOSE_WAIT &&
 227         (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
 228         conn->fin_ack_seq = ntohl(tcp_pkt->th_seq);
 229         conn->tcp_state = TCPS_LAST_ACK;
 230     }
 231
 232     /*
 233      * Active close
 234      *
 235      * Step 1:
 236      * The *server* side of this connect is VM, *server* tries to close
 237      * the connection.
 238      *
 239      * Step 2:
 240      * We will into CLOSE_WAIT status.
 241      * We simplify the TCPS_FIN_WAIT_2, TCPS_TIME_WAIT and
 242      * CLOSING status.
 243      */
 244     if (conn->tcp_state == TCPS_ESTABLISHED &&
 245         (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == TH_FIN) {
 246         conn->tcp_state = TCPS_FIN_WAIT_1;
 247     }
 248
 249     return 0;
 250 }
 251
 252 static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
 253                                          NetClientState *sender,
 254                                          unsigned flags,
 255                                          const struct iovec *iov,
 256                                          int iovcnt,
 257                                          NetPacketSent *sent_cb)
 258 {
 259     RewriterState *s = FILTER_REWRITER(nf);
 260     Connection *conn;
 261     ConnectionKey key;
 262     Packet *pkt;
 263     ssize_t size = iov_size(iov, iovcnt);
 264     ssize_t vnet_hdr_len = 0;
 265     char *buf = g_malloc0(size);
 266
 267     iov_to_buf(iov, iovcnt, 0, buf, size);
 268
 269     if (s->vnet_hdr) {
 270         vnet_hdr_len = nf->netdev->vnet_hdr_len;
 271     }
 272
 273     pkt = packet_new_nocopy(buf, size, vnet_hdr_len);
 274
 275     /*
 276      * if we get tcp packet
 277      * we will rewrite it to make secondary guest's
 278      * connection established successfully
 279      */
 280     if (pkt && is_tcp_packet(pkt)) {
 281
 282         fill_connection_key(pkt, &key, sender == nf->netdev);
 283
 284         /* After failover we needn't change new TCP packet */
 285         if (s->failover_mode &&
 286             !connection_has_tracked(s->connection_track_table, &key)) {
 287             goto out;
 288         }
 289
 290         conn = connection_get(s->connection_track_table,
 291                               &key,
 292                               NULL);
 293
 294         if (sender == nf->netdev) {
 295             /* NET_FILTER_DIRECTION_TX */
 296             if (!handle_primary_tcp_pkt(s, conn, pkt, &key)) {
 297                 qemu_net_queue_send(s->incoming_queue, sender, 0,
 298                 (const uint8_t *)pkt->data, pkt->size, NULL);
 299                 packet_destroy(pkt, NULL);
 300                 pkt = NULL;
 301                 /*
 302                  * We block the packet here,after rewrite pkt
 303                  * and will send it
 304                  */
 305                 return 1;
 306             }
 307         } else {
 308             /* NET_FILTER_DIRECTION_RX */
 309             if (!handle_secondary_tcp_pkt(s, conn, pkt, &key)) {
 310                 qemu_net_queue_send(s->incoming_queue, sender, 0,
 311                 (const uint8_t *)pkt->data, pkt->size, NULL);
 312                 packet_destroy(pkt, NULL);
 313                 pkt = NULL;
 314                 /*
 315                  * We block the packet here,after rewrite pkt
 316                  * and will send it
 317                  */
 318                 return 1;
 319             }
 320         }
 321     }
 322
 323 out:
 324     packet_destroy(pkt, NULL);
 325     pkt = NULL;
 326     return 0;
 327 }
 328
 329 static void reset_seq_offset(gpointer key, gpointer value, gpointer user_data)
 330 {
 331     Connection *conn = (Connection *)value;
 332
 333     conn->offset = 0;
 334 }
 335
 336 static gboolean offset_is_nonzero(gpointer key,
 337                                   gpointer value,
 338                                   gpointer user_data)
 339 {
 340     Connection *conn = (Connection *)value;
 341
 342     return conn->offset ? true : false;
 343 }
 344
 345 static void colo_rewriter_handle_event(NetFilterState *nf, int event,
 346                                        Error **errp)
 347 {
 348     RewriterState *rs = FILTER_REWRITER(nf);
 349
 350     switch (event) {
 351     case COLO_EVENT_CHECKPOINT:
 352         g_hash_table_foreach(rs->connection_track_table,
 353                             reset_seq_offset, NULL);
 354         break;
 355     case COLO_EVENT_FAILOVER:
 356         if (!g_hash_table_find(rs->connection_track_table,
 357                               offset_is_nonzero, NULL)) {
 358             filter_rewriter_failover_mode(rs);
 359         }
 360         break;
 361     default:
 362         break;
 363     }
 364 }
 365
 366 static void colo_rewriter_cleanup(NetFilterState *nf)
 367 {
 368     RewriterState *s = FILTER_REWRITER(nf);
 369
 370     /* flush packets */
 371     if (s->incoming_queue) {
 372         filter_rewriter_flush(nf);
 373         g_free(s->incoming_queue);
 374     }
 375
 376     g_hash_table_destroy(s->connection_track_table);
 377 }
 378
 379 static void colo_rewriter_setup(NetFilterState *nf, Error **errp)
 380 {
 381     RewriterState *s = FILTER_REWRITER(nf);
 382
 383     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
 384                                                       connection_key_equal,
 385                                                       g_free,
 386                                                       connection_destroy);
 387     s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
 388 }
 389
 390 static bool filter_rewriter_get_vnet_hdr(Object *obj, Error **errp)
 391 {
 392     RewriterState *s = FILTER_REWRITER(obj);
 393
 394     return s->vnet_hdr;
 395 }
 396
 397 static void filter_rewriter_set_vnet_hdr(Object *obj,
 398                                          bool value,
 399                                          Error **errp)
 400 {
 401     RewriterState *s = FILTER_REWRITER(obj);
 402
 403     s->vnet_hdr = value;
 404 }
 405
 406 static void filter_rewriter_init(Object *obj)
 407 {
 408     RewriterState *s = FILTER_REWRITER(obj);
 409
 410     s->vnet_hdr = false;
 411     s->failover_mode = FAILOVER_MODE_OFF;
 412 }
 413
 414 static void colo_rewriter_class_init(ObjectClass *oc, void *data)
 415 {
 416     NetFilterClass *nfc = NETFILTER_CLASS(oc);
 417
 418     object_class_property_add_bool(oc, "vnet_hdr_support",
 419                                    filter_rewriter_get_vnet_hdr,
 420                                    filter_rewriter_set_vnet_hdr);
 421
 422     nfc->setup = colo_rewriter_setup;
 423     nfc->cleanup = colo_rewriter_cleanup;
 424     nfc->receive_iov = colo_rewriter_receive_iov;
 425     nfc->handle_event = colo_rewriter_handle_event;
 426 }
 427
 428 static const TypeInfo colo_rewriter_info = {
 429     .name = TYPE_FILTER_REWRITER,
 430     .parent = TYPE_NETFILTER,
 431     .class_init = colo_rewriter_class_init,
 432     .instance_init = filter_rewriter_init,
 433     .instance_size = sizeof(RewriterState),
 434 };
 435
 436 static void register_types(void)
 437 {
 438     type_register_static(&colo_rewriter_info);
 439 }
 440
 441 type_init(register_types);