qemu

filter-rewriter.c (13730B)

---

 /*
  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
  * Copyright (c) 2016 FUJITSU LIMITED
  * Copyright (c) 2016 Intel Corporation
  *
  * Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or
  * later.  See the COPYING file in the top-level directory.
  */
 
 #include "qemu/osdep.h"
 #include "trace.h"
 #include "colo.h"
 #include "net/filter.h"
 #include "net/net.h"
 #include "qemu/error-report.h"
 #include "qom/object.h"
 #include "qemu/main-loop.h"
 #include "qemu/iov.h"
 #include "net/checksum.h"
 #include "net/colo.h"
 #include "migration/colo.h"
 #include "util.h"
 
 #define TYPE_FILTER_REWRITER "filter-rewriter"
 OBJECT_DECLARE_SIMPLE_TYPE(RewriterState, FILTER_REWRITER)
 
 #define FAILOVER_MODE_ON  true
 #define FAILOVER_MODE_OFF false
 
 struct RewriterState {
     NetFilterState parent_obj;
     NetQueue *incoming_queue;
     /* hashtable to save connection */
     GHashTable *connection_track_table;
     bool vnet_hdr;
     bool failover_mode;
 };
 
 static void filter_rewriter_failover_mode(RewriterState *s)
 {
     s->failover_mode = FAILOVER_MODE_ON;
 }
 
 static void filter_rewriter_flush(NetFilterState *nf)
 {
     RewriterState *s = FILTER_REWRITER(nf);
 
     if (!qemu_net_queue_flush(s->incoming_queue)) {
         /* Unable to empty the queue, purge remaining packets */
         qemu_net_queue_purge(s->incoming_queue, nf->netdev);
     }
 }
 
 /*
  * Return 1 on success, if return 0 means the pkt
  * is not TCP packet
  */
 static int is_tcp_packet(Packet *pkt)
 {
     if (!parse_packet_early(pkt) &&
         pkt->ip->ip_p == IPPROTO_TCP) {
         return 1;
     } else {
         return 0;
     }
 }
 
 /* handle tcp packet from primary guest */
 static int handle_primary_tcp_pkt(RewriterState *rf,
                                   Connection *conn,
                                   Packet *pkt, ConnectionKey *key)
 {
     struct tcp_hdr *tcp_pkt;
 
     tcp_pkt = (struct tcp_hdr *)pkt->transport_header;
     if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO)) {
         trace_colo_filter_rewriter_pkt_info(__func__,
                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
                     tcp_pkt->th_flags);
     }
     if (trace_event_get_state_backends(
           TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) {
         trace_colo_filter_rewriter_conn_offset(conn->offset);
     }
 
     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN)) &&
         conn->tcp_state == TCPS_SYN_SENT) {
         conn->tcp_state = TCPS_ESTABLISHED;
     }
 
     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
         /*
          * we use this flag update offset func
          * run once in independent tcp connection
          */
         conn->tcp_state = TCPS_SYN_RECEIVED;
     }
 
     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
         if (conn->tcp_state == TCPS_SYN_RECEIVED) {
             /*
              * offset = secondary_seq - primary seq
              * ack packet sent by guest from primary node,
              * so we use th_ack - 1 get primary_seq
              */
             conn->offset -= (ntohl(tcp_pkt->th_ack) - 1);
             conn->tcp_state = TCPS_ESTABLISHED;
         }
         if (conn->offset) {
             /* handle packets to the secondary from the primary */
             tcp_pkt->th_ack = htonl(ntohl(tcp_pkt->th_ack) + conn->offset);
 
             net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
                                    pkt->size - pkt->vnet_hdr_len, CSUM_TCP);
         }
 
         /*
          * Passive close step 3
          */
         if ((conn->tcp_state == TCPS_LAST_ACK) &&
             (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
             conn->tcp_state = TCPS_CLOSED;
             g_hash_table_remove(rf->connection_track_table, key);
         }
     }
 
     if ((tcp_pkt->th_flags & TH_FIN) == TH_FIN) {
         /*
          * Passive close.
          * Step 1:
          * The *server* side of this connect is VM, *client* tries to close
          * the connection. We will into CLOSE_WAIT status.
          *
          * Step 2:
          * In this step we will into LAST_ACK status.
          *
          * We got 'fin=1, ack=1' packet from server side, we need to
          * record the seq of 'fin=1, ack=1' packet.
          *
          * Step 3:
          * We got 'ack=1' packets from client side, it acks 'fin=1, ack=1'
          * packet from server side. From this point, we can ensure that there
          * will be no packets in the connection, except that, some errors
          * happen between the path of 'filter object' and vNIC, if this rare
          * case really happen, we can still create a new connection,
          * So it is safe to remove the connection from connection_track_table.
          *
          */
         if (conn->tcp_state == TCPS_ESTABLISHED) {
             conn->tcp_state = TCPS_CLOSE_WAIT;
         }
 
         /*
          * Active close step 2.
          */
         if (conn->tcp_state == TCPS_FIN_WAIT_1) {
             /*
              * For simplify implementation, we needn't wait 2MSL time
              * in filter rewriter. Because guest kernel will track the
              * TCP status and wait 2MSL time, if client resend the FIN
              * packet, guest will apply the last ACK too.
              * So, we skip the TCPS_TIME_WAIT state here and go straight
              * to TCPS_CLOSED state.
              */
             conn->tcp_state = TCPS_CLOSED;
             g_hash_table_remove(rf->connection_track_table, key);
         }
     }
 
     return 0;
 }
 
 /* handle tcp packet from secondary guest */
 static int handle_secondary_tcp_pkt(RewriterState *rf,
                                     Connection *conn,
                                     Packet *pkt, ConnectionKey *key)
 {
     struct tcp_hdr *tcp_pkt;
 
     tcp_pkt = (struct tcp_hdr *)pkt->transport_header;
 
     if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO)) {
         trace_colo_filter_rewriter_pkt_info(__func__,
                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
                     tcp_pkt->th_flags);
     }
     if (trace_event_get_state_backends(
           TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) {
         trace_colo_filter_rewriter_conn_offset(conn->offset);
     }
 
     if (conn->tcp_state == TCPS_SYN_RECEIVED &&
         ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
         /*
          * save offset = secondary_seq and then
          * in handle_primary_tcp_pkt make offset
          * = secondary_seq - primary_seq
          */
         conn->offset = ntohl(tcp_pkt->th_seq);
     }
 
     /* VM active connect */
     if (conn->tcp_state == TCPS_CLOSED &&
         ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
         conn->tcp_state = TCPS_SYN_SENT;
     }
 
     if ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK) {
         /* Only need to adjust seq while offset is Non-zero */
         if (conn->offset) {
             /* handle packets to the primary from the secondary*/
             tcp_pkt->th_seq = htonl(ntohl(tcp_pkt->th_seq) - conn->offset);
 
             net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
                                    pkt->size - pkt->vnet_hdr_len, CSUM_TCP);
         }
     }
 
     /*
      * Passive close step 2:
      */
     if (conn->tcp_state == TCPS_CLOSE_WAIT &&
         (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
         conn->fin_ack_seq = ntohl(tcp_pkt->th_seq);
         conn->tcp_state = TCPS_LAST_ACK;
     }
 
     /*
      * Active close
      *
      * Step 1:
      * The *server* side of this connect is VM, *server* tries to close
      * the connection.
      *
      * Step 2:
      * We will into CLOSE_WAIT status.
      * We simplify the TCPS_FIN_WAIT_2, TCPS_TIME_WAIT and
      * CLOSING status.
      */
     if (conn->tcp_state == TCPS_ESTABLISHED &&
         (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == TH_FIN) {
         conn->tcp_state = TCPS_FIN_WAIT_1;
     }
 
     return 0;
 }
 
 static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
                                          NetClientState *sender,
                                          unsigned flags,
                                          const struct iovec *iov,
                                          int iovcnt,
                                          NetPacketSent *sent_cb)
 {
     RewriterState *s = FILTER_REWRITER(nf);
     Connection *conn;
     ConnectionKey key;
     Packet *pkt;
     ssize_t size = iov_size(iov, iovcnt);
     ssize_t vnet_hdr_len = 0;
     char *buf = g_malloc0(size);
 
     iov_to_buf(iov, iovcnt, 0, buf, size);
 
     if (s->vnet_hdr) {
         vnet_hdr_len = nf->netdev->vnet_hdr_len;
     }
 
     pkt = packet_new_nocopy(buf, size, vnet_hdr_len);
 
     /*
      * if we get tcp packet
      * we will rewrite it to make secondary guest's
      * connection established successfully
      */
     if (pkt && is_tcp_packet(pkt)) {
 
         fill_connection_key(pkt, &key, sender == nf->netdev);
 
         /* After failover we needn't change new TCP packet */
         if (s->failover_mode &&
             !connection_has_tracked(s->connection_track_table, &key)) {
             goto out;
         }
 
         conn = connection_get(s->connection_track_table,
                               &key,
                               NULL);
 
         if (sender == nf->netdev) {
             /* NET_FILTER_DIRECTION_TX */
             if (!handle_primary_tcp_pkt(s, conn, pkt, &key)) {
                 qemu_net_queue_send(s->incoming_queue, sender, 0,
                 (const uint8_t *)pkt->data, pkt->size, NULL);
                 packet_destroy(pkt, NULL);
                 pkt = NULL;
                 /*
                  * We block the packet here,after rewrite pkt
                  * and will send it
                  */
                 return 1;
             }
         } else {
             /* NET_FILTER_DIRECTION_RX */
             if (!handle_secondary_tcp_pkt(s, conn, pkt, &key)) {
                 qemu_net_queue_send(s->incoming_queue, sender, 0,
                 (const uint8_t *)pkt->data, pkt->size, NULL);
                 packet_destroy(pkt, NULL);
                 pkt = NULL;
                 /*
                  * We block the packet here,after rewrite pkt
                  * and will send it
                  */
                 return 1;
             }
         }
     }
 
 out:
     packet_destroy(pkt, NULL);
     pkt = NULL;
     return 0;
 }
 
 static void reset_seq_offset(gpointer key, gpointer value, gpointer user_data)
 {
     Connection *conn = (Connection *)value;
 
     conn->offset = 0;
 }
 
 static gboolean offset_is_nonzero(gpointer key,
                                   gpointer value,
                                   gpointer user_data)
 {
     Connection *conn = (Connection *)value;
 
     return conn->offset ? true : false;
 }
 
 static void colo_rewriter_handle_event(NetFilterState *nf, int event,
                                        Error **errp)
 {
     RewriterState *rs = FILTER_REWRITER(nf);
 
     switch (event) {
     case COLO_EVENT_CHECKPOINT:
         g_hash_table_foreach(rs->connection_track_table,
                             reset_seq_offset, NULL);
         break;
     case COLO_EVENT_FAILOVER:
         if (!g_hash_table_find(rs->connection_track_table,
                               offset_is_nonzero, NULL)) {
             filter_rewriter_failover_mode(rs);
         }
         break;
     default:
         break;
     }
 }
 
 static void colo_rewriter_cleanup(NetFilterState *nf)
 {
     RewriterState *s = FILTER_REWRITER(nf);
 
     /* flush packets */
     if (s->incoming_queue) {
         filter_rewriter_flush(nf);
         g_free(s->incoming_queue);
     }
 
     g_hash_table_destroy(s->connection_track_table);
 }
 
 static void colo_rewriter_setup(NetFilterState *nf, Error **errp)
 {
     RewriterState *s = FILTER_REWRITER(nf);
 
     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
                                                       connection_key_equal,
                                                       g_free,
                                                       NULL);
     s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
 }
 
 static bool filter_rewriter_get_vnet_hdr(Object *obj, Error **errp)
 {
     RewriterState *s = FILTER_REWRITER(obj);
 
     return s->vnet_hdr;
 }
 
 static void filter_rewriter_set_vnet_hdr(Object *obj,
                                          bool value,
                                          Error **errp)
 {
     RewriterState *s = FILTER_REWRITER(obj);
 
     s->vnet_hdr = value;
 }
 
 static void filter_rewriter_init(Object *obj)
 {
     RewriterState *s = FILTER_REWRITER(obj);
 
     s->vnet_hdr = false;
     s->failover_mode = FAILOVER_MODE_OFF;
 }
 
 static void colo_rewriter_class_init(ObjectClass *oc, void *data)
 {
     NetFilterClass *nfc = NETFILTER_CLASS(oc);
 
     object_class_property_add_bool(oc, "vnet_hdr_support",
                                    filter_rewriter_get_vnet_hdr,
                                    filter_rewriter_set_vnet_hdr);
 
     nfc->setup = colo_rewriter_setup;
     nfc->cleanup = colo_rewriter_cleanup;
     nfc->receive_iov = colo_rewriter_receive_iov;
     nfc->handle_event = colo_rewriter_handle_event;
 }
 
 static const TypeInfo colo_rewriter_info = {
     .name = TYPE_FILTER_REWRITER,
     .parent = TYPE_NETFILTER,
     .class_init = colo_rewriter_class_init,
     .instance_init = filter_rewriter_init,
     .instance_size = sizeof(RewriterState),
 };
 
 static void register_types(void)
 {
     type_register_static(&colo_rewriter_info);
 }
 
 type_init(register_types);