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
|
/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2009 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "tap_int.h"
#include "tap-linux.h"
#include "net/tap.h"
#include <net/if.h>
#include <sys/ioctl.h>
#include "sysemu.h"
#include "qemu-common.h"
#include "qemu/error-report.h"
#define PATH_NET_TUN "/dev/net/tun"
int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required)
{
struct ifreq ifr;
int fd, ret;
int len = sizeof(struct virtio_net_hdr);
TFR(fd = open(PATH_NET_TUN, O_RDWR));
if (fd < 0) {
error_report("could not open %s: %m", PATH_NET_TUN);
return -1;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
if (*vnet_hdr) {
unsigned int features;
if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
features & IFF_VNET_HDR) {
*vnet_hdr = 1;
ifr.ifr_flags |= IFF_VNET_HDR;
} else {
*vnet_hdr = 0;
}
if (vnet_hdr_required && !*vnet_hdr) {
error_report("vnet_hdr=1 requested, but no kernel "
"support for IFF_VNET_HDR available");
close(fd);
return -1;
}
/*
* Make sure vnet header size has the default value: for a persistent
* tap it might have been modified e.g. by another instance of qemu.
* Ignore errors since old kernels do not support this ioctl: in this
* case the header size implicitly has the correct value.
*/
ioctl(fd, TUNSETVNETHDRSZ, &len);
}
if (ifname[0] != '\0')
pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
else
pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
if (ret != 0) {
if (ifname[0] != '\0') {
error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name);
} else {
error_report("could not configure %s: %m", PATH_NET_TUN);
}
close(fd);
return -1;
}
pstrcpy(ifname, ifname_size, ifr.ifr_name);
fcntl(fd, F_SETFL, O_NONBLOCK);
return fd;
}
/* sndbuf implements a kind of flow control for tap.
* Unfortunately when it's enabled, and packets are sent
* to other guests on the same host, the receiver
* can lock up the transmitter indefinitely.
*
* To avoid packet loss, sndbuf should be set to a value lower than the tx
* queue capacity of any destination network interface.
* Ethernet NICs generally have txqueuelen=1000, so 1Mb is
* a good value, given a 1500 byte MTU.
*/
#define TAP_DEFAULT_SNDBUF 0
int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
{
int sndbuf;
sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF :
tap->sndbuf > INT_MAX ? INT_MAX :
tap->sndbuf;
if (!sndbuf) {
sndbuf = INT_MAX;
}
if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
error_report("TUNSETSNDBUF ioctl failed: %s", strerror(errno));
return -1;
}
return 0;
}
int tap_probe_vnet_hdr(int fd)
{
struct ifreq ifr;
if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
error_report("TUNGETIFF ioctl() failed: %s", strerror(errno));
return 0;
}
return ifr.ifr_flags & IFF_VNET_HDR;
}
int tap_probe_has_ufo(int fd)
{
unsigned offload;
offload = TUN_F_CSUM | TUN_F_UFO;
if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
return 0;
return 1;
}
/* Verify that we can assign given length */
int tap_probe_vnet_hdr_len(int fd, int len)
{
int orig;
if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
return 0;
}
if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
return 0;
}
/* Restore original length: we can't handle failure. */
if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
strerror(errno));
assert(0);
return -errno;
}
return 1;
}
void tap_fd_set_vnet_hdr_len(int fd, int len)
{
if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
strerror(errno));
assert(0);
}
}
void tap_fd_set_offload(int fd, int csum, int tso4,
int tso6, int ecn, int ufo)
{
unsigned int offload = 0;
/* Check if our kernel supports TUNSETOFFLOAD */
if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
return;
}
if (csum) {
offload |= TUN_F_CSUM;
if (tso4)
offload |= TUN_F_TSO4;
if (tso6)
offload |= TUN_F_TSO6;
if ((tso4 || tso6) && ecn)
offload |= TUN_F_TSO_ECN;
if (ufo)
offload |= TUN_F_UFO;
}
if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
offload &= ~TUN_F_UFO;
if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
strerror(errno));
}
}
}
|
