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