xref: /qemu/net/filter-rewriter.c (revision 6402cbbb) 
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 "net/colo.h"
15 #include "net/filter.h"
16 #include "net/net.h"
17 #include "qemu-common.h"
18 #include "qapi/error.h"
19 #include "qapi/qmp/qerror.h"
20 #include "qemu/error-report.h"
21 #include "qapi-visit.h"
22 #include "qom/object.h"
23 #include "qemu/main-loop.h"
24 #include "qemu/iov.h"
25 #include "net/checksum.h"
26 
27 #define FILTER_COLO_REWRITER(obj) \
28     OBJECT_CHECK(RewriterState, (obj), TYPE_FILTER_REWRITER)
29 
30 #define TYPE_FILTER_REWRITER "filter-rewriter"
31 
32 typedef 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 } RewriterState;
39 
40 static void filter_rewriter_flush(NetFilterState *nf)
41 {
42     RewriterState *s = FILTER_COLO_REWRITER(nf);
43 
44     if (!qemu_net_queue_flush(s->incoming_queue)) {
45         /* Unable to empty the queue, purge remaining packets */
46         qemu_net_queue_purge(s->incoming_queue, nf->netdev);
47     }
48 }
49 
50 /*
51  * Return 1 on success, if return 0 means the pkt
52  * is not TCP packet
53  */
54 static int is_tcp_packet(Packet *pkt)
55 {
56     if (!parse_packet_early(pkt) &&
57         pkt->ip->ip_p == IPPROTO_TCP) {
58         return 1;
59     } else {
60         return 0;
61     }
62 }
63 
64 /* handle tcp packet from primary guest */
65 static int handle_primary_tcp_pkt(NetFilterState *nf,
66                                   Connection *conn,
67                                   Packet *pkt)
68 {
69     struct tcphdr *tcp_pkt;
70 
71     tcp_pkt = (struct tcphdr *)pkt->transport_header;
72     if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
73         trace_colo_filter_rewriter_pkt_info(__func__,
74                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
75                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
76                     tcp_pkt->th_flags);
77         trace_colo_filter_rewriter_conn_offset(conn->offset);
78     }
79 
80     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
81         /*
82          * we use this flag update offset func
83          * run once in independent tcp connection
84          */
85         conn->syn_flag = 1;
86     }
87 
88     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
89         if (conn->syn_flag) {
90             /*
91              * offset = secondary_seq - primary seq
92              * ack packet sent by guest from primary node,
93              * so we use th_ack - 1 get primary_seq
94              */
95             conn->offset -= (ntohl(tcp_pkt->th_ack) - 1);
96             conn->syn_flag = 0;
97         }
98         if (conn->offset) {
99             /* handle packets to the secondary from the primary */
100             tcp_pkt->th_ack = htonl(ntohl(tcp_pkt->th_ack) + conn->offset);
101 
102             net_checksum_calculate((uint8_t *)pkt->data, pkt->size);
103         }
104     }
105 
106     return 0;
107 }
108 
109 /* handle tcp packet from secondary guest */
110 static int handle_secondary_tcp_pkt(NetFilterState *nf,
111                                     Connection *conn,
112                                     Packet *pkt)
113 {
114     struct tcphdr *tcp_pkt;
115 
116     tcp_pkt = (struct tcphdr *)pkt->transport_header;
117 
118     if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {
119         trace_colo_filter_rewriter_pkt_info(__func__,
120                     inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst),
121                     ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack),
122                     tcp_pkt->th_flags);
123         trace_colo_filter_rewriter_conn_offset(conn->offset);
124     }
125 
126     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
127         /*
128          * save offset = secondary_seq and then
129          * in handle_primary_tcp_pkt make offset
130          * = secondary_seq - primary_seq
131          */
132         conn->offset = ntohl(tcp_pkt->th_seq);
133     }
134 
135     if ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK) {
136         /* Only need to adjust seq while offset is Non-zero */
137         if (conn->offset) {
138             /* handle packets to the primary from the secondary*/
139             tcp_pkt->th_seq = htonl(ntohl(tcp_pkt->th_seq) - conn->offset);
140 
141             net_checksum_calculate((uint8_t *)pkt->data, pkt->size);
142         }
143     }
144 
145     return 0;
146 }
147 
148 static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
149                                          NetClientState *sender,
150                                          unsigned flags,
151                                          const struct iovec *iov,
152                                          int iovcnt,
153                                          NetPacketSent *sent_cb)
154 {
155     RewriterState *s = FILTER_COLO_REWRITER(nf);
156     Connection *conn;
157     ConnectionKey key;
158     Packet *pkt;
159     ssize_t size = iov_size(iov, iovcnt);
160     ssize_t vnet_hdr_len = 0;
161     char *buf = g_malloc0(size);
162 
163     iov_to_buf(iov, iovcnt, 0, buf, size);
164 
165     if (s->vnet_hdr) {
166         vnet_hdr_len = nf->netdev->vnet_hdr_len;
167     }
168 
169     pkt = packet_new(buf, size, vnet_hdr_len);
170     g_free(buf);
171 
172     /*
173      * if we get tcp packet
174      * we will rewrite it to make secondary guest's
175      * connection established successfully
176      */
177     if (pkt && is_tcp_packet(pkt)) {
178 
179         fill_connection_key(pkt, &key);
180 
181         if (sender == nf->netdev) {
182             /*
183              * We need make tcp TX and RX packet
184              * into one connection.
185              */
186             reverse_connection_key(&key);
187         }
188         conn = connection_get(s->connection_track_table,
189                               &key,
190                               NULL);
191 
192         if (sender == nf->netdev) {
193             /* NET_FILTER_DIRECTION_TX */
194             if (!handle_primary_tcp_pkt(nf, conn, pkt)) {
195                 qemu_net_queue_send(s->incoming_queue, sender, 0,
196                 (const uint8_t *)pkt->data, pkt->size, NULL);
197                 packet_destroy(pkt, NULL);
198                 pkt = NULL;
199                 /*
200                  * We block the packet here,after rewrite pkt
201                  * and will send it
202                  */
203                 return 1;
204             }
205         } else {
206             /* NET_FILTER_DIRECTION_RX */
207             if (!handle_secondary_tcp_pkt(nf, conn, pkt)) {
208                 qemu_net_queue_send(s->incoming_queue, sender, 0,
209                 (const uint8_t *)pkt->data, pkt->size, NULL);
210                 packet_destroy(pkt, NULL);
211                 pkt = NULL;
212                 /*
213                  * We block the packet here,after rewrite pkt
214                  * and will send it
215                  */
216                 return 1;
217             }
218         }
219     }
220 
221     packet_destroy(pkt, NULL);
222     pkt = NULL;
223     return 0;
224 }
225 
226 static void colo_rewriter_cleanup(NetFilterState *nf)
227 {
228     RewriterState *s = FILTER_COLO_REWRITER(nf);
229 
230     /* flush packets */
231     if (s->incoming_queue) {
232         filter_rewriter_flush(nf);
233         g_free(s->incoming_queue);
234     }
235 }
236 
237 static void colo_rewriter_setup(NetFilterState *nf, Error **errp)
238 {
239     RewriterState *s = FILTER_COLO_REWRITER(nf);
240 
241     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
242                                                       connection_key_equal,
243                                                       g_free,
244                                                       connection_destroy);
245     s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
246 }
247 
248 static bool filter_rewriter_get_vnet_hdr(Object *obj, Error **errp)
249 {
250     RewriterState *s = FILTER_COLO_REWRITER(obj);
251 
252     return s->vnet_hdr;
253 }
254 
255 static void filter_rewriter_set_vnet_hdr(Object *obj,
256                                          bool value,
257                                          Error **errp)
258 {
259     RewriterState *s = FILTER_COLO_REWRITER(obj);
260 
261     s->vnet_hdr = value;
262 }
263 
264 static void filter_rewriter_init(Object *obj)
265 {
266     RewriterState *s = FILTER_COLO_REWRITER(obj);
267 
268     s->vnet_hdr = false;
269     object_property_add_bool(obj, "vnet_hdr_support",
270                              filter_rewriter_get_vnet_hdr,
271                              filter_rewriter_set_vnet_hdr, NULL);
272 }
273 
274 static void colo_rewriter_class_init(ObjectClass *oc, void *data)
275 {
276     NetFilterClass *nfc = NETFILTER_CLASS(oc);
277 
278     nfc->setup = colo_rewriter_setup;
279     nfc->cleanup = colo_rewriter_cleanup;
280     nfc->receive_iov = colo_rewriter_receive_iov;
281 }
282 
283 static const TypeInfo colo_rewriter_info = {
284     .name = TYPE_FILTER_REWRITER,
285     .parent = TYPE_NETFILTER,
286     .class_init = colo_rewriter_class_init,
287     .instance_init = filter_rewriter_init,
288     .instance_size = sizeof(RewriterState),
289 };
290 
291 static void register_types(void)
292 {
293     type_register_static(&colo_rewriter_info);
294 }
295 
296 type_init(register_types);
297