aboutsummaryrefslogtreecommitdiff
path: root/net/filter-rewriter.c
blob: 2be388f53973d0fba91eda9a61092346d3549b5e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
/*
 * 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 "net/colo.h"
#include "net/filter.h"
#include "net/net.h"
#include "qemu-common.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qemu/error-report.h"
#include "qapi-visit.h"
#include "qom/object.h"
#include "qemu/main-loop.h"
#include "qemu/iov.h"
#include "net/checksum.h"

#define FILTER_COLO_REWRITER(obj) \
    OBJECT_CHECK(RewriterState, (obj), TYPE_FILTER_REWRITER)

#define TYPE_FILTER_REWRITER "filter-rewriter"

typedef struct RewriterState {
    NetFilterState parent_obj;
    NetQueue *incoming_queue;
    /* hashtable to save connection */
    GHashTable *connection_track_table;
    bool vnet_hdr;
} RewriterState;

static void filter_rewriter_flush(NetFilterState *nf)
{
    RewriterState *s = FILTER_COLO_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(NetFilterState *nf,
                                  Connection *conn,
                                  Packet *pkt)
{
    struct tcphdr *tcp_pkt;

    tcp_pkt = (struct tcphdr *)pkt->transport_header;
    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
        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);
        trace_colo_filter_rewriter_conn_offset(conn->offset);
    }

    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->syn_flag = 1;
    }

    if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
        if (conn->syn_flag) {
            /*
             * 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->syn_flag = 0;
        }
        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);
        }
    }

    return 0;
}

/* handle tcp packet from secondary guest */
static int handle_secondary_tcp_pkt(NetFilterState *nf,
                                    Connection *conn,
                                    Packet *pkt)
{
    struct tcphdr *tcp_pkt;

    tcp_pkt = (struct tcphdr *)pkt->transport_header;

    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
        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);
        trace_colo_filter_rewriter_conn_offset(conn->offset);
    }

    if (((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);
    }

    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);
        }
    }

    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_COLO_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(buf, size, vnet_hdr_len);
    g_free(buf);

    /*
     * 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);

        if (sender == nf->netdev) {
            /*
             * We need make tcp TX and RX packet
             * into one connection.
             */
            reverse_connection_key(&key);
        }
        conn = connection_get(s->connection_track_table,
                              &key,
                              NULL);

        if (sender == nf->netdev) {
            /* NET_FILTER_DIRECTION_TX */
            if (!handle_primary_tcp_pkt(nf, conn, pkt)) {
                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(nf, conn, pkt)) {
                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;
            }
        }
    }

    packet_destroy(pkt, NULL);
    pkt = NULL;
    return 0;
}

static void colo_rewriter_cleanup(NetFilterState *nf)
{
    RewriterState *s = FILTER_COLO_REWRITER(nf);

    /* flush packets */
    if (s->incoming_queue) {
        filter_rewriter_flush(nf);
        g_free(s->incoming_queue);
    }
}

static void colo_rewriter_setup(NetFilterState *nf, Error **errp)
{
    RewriterState *s = FILTER_COLO_REWRITER(nf);

    s->connection_track_table = g_hash_table_new_full(connection_key_hash,
                                                      connection_key_equal,
                                                      g_free,
                                                      connection_destroy);
    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_COLO_REWRITER(obj);

    return s->vnet_hdr;
}

static void filter_rewriter_set_vnet_hdr(Object *obj,
                                         bool value,
                                         Error **errp)
{
    RewriterState *s = FILTER_COLO_REWRITER(obj);

    s->vnet_hdr = value;
}

static void filter_rewriter_init(Object *obj)
{
    RewriterState *s = FILTER_COLO_REWRITER(obj);

    s->vnet_hdr = false;
    object_property_add_bool(obj, "vnet_hdr_support",
                             filter_rewriter_get_vnet_hdr,
                             filter_rewriter_set_vnet_hdr, NULL);
}

static void colo_rewriter_class_init(ObjectClass *oc, void *data)
{
    NetFilterClass *nfc = NETFILTER_CLASS(oc);

    nfc->setup = colo_rewriter_setup;
    nfc->cleanup = colo_rewriter_cleanup;
    nfc->receive_iov = colo_rewriter_receive_iov;
}

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);