1 /* 2 * QEMU System Emulator 3 * 4 * Copyright (c) 2003-2008 Fabrice Bellard 5 * Copyright (c) 2009 Red Hat, Inc. 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 */ 25 26 #include "qemu/osdep.h" 27 #include "qemu-common.h" 28 #include "tap_int.h" 29 #include "tap-linux.h" 30 #include "net/tap.h" 31 32 #include <net/if.h> 33 #include <sys/ioctl.h> 34 35 #include "sysemu/sysemu.h" 36 #include "qapi/error.h" 37 #include "qemu/error-report.h" 38 #include "qemu/cutils.h" 39 40 #define PATH_NET_TUN "/dev/net/tun" 41 42 int tap_open(char *ifname, int ifname_size, int *vnet_hdr, 43 int vnet_hdr_required, int mq_required, Error **errp) 44 { 45 struct ifreq ifr; 46 int fd, ret; 47 int len = sizeof(struct virtio_net_hdr); 48 unsigned int features; 49 50 TFR(fd = open(PATH_NET_TUN, O_RDWR)); 51 if (fd < 0) { 52 error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN); 53 return -1; 54 } 55 memset(&ifr, 0, sizeof(ifr)); 56 ifr.ifr_flags = IFF_TAP | IFF_NO_PI; 57 58 if (ioctl(fd, TUNGETFEATURES, &features) == -1) { 59 warn_report("TUNGETFEATURES failed: %s", strerror(errno)); 60 features = 0; 61 } 62 63 if (features & IFF_ONE_QUEUE) { 64 ifr.ifr_flags |= IFF_ONE_QUEUE; 65 } 66 67 if (*vnet_hdr) { 68 if (features & IFF_VNET_HDR) { 69 *vnet_hdr = 1; 70 ifr.ifr_flags |= IFF_VNET_HDR; 71 } else { 72 *vnet_hdr = 0; 73 } 74 75 if (vnet_hdr_required && !*vnet_hdr) { 76 error_setg(errp, "vnet_hdr=1 requested, but no kernel " 77 "support for IFF_VNET_HDR available"); 78 close(fd); 79 return -1; 80 } 81 /* 82 * Make sure vnet header size has the default value: for a persistent 83 * tap it might have been modified e.g. by another instance of qemu. 84 * Ignore errors since old kernels do not support this ioctl: in this 85 * case the header size implicitly has the correct value. 86 */ 87 ioctl(fd, TUNSETVNETHDRSZ, &len); 88 } 89 90 if (mq_required) { 91 if (!(features & IFF_MULTI_QUEUE)) { 92 error_setg(errp, "multiqueue required, but no kernel " 93 "support for IFF_MULTI_QUEUE available"); 94 close(fd); 95 return -1; 96 } else { 97 ifr.ifr_flags |= IFF_MULTI_QUEUE; 98 } 99 } 100 101 if (ifname[0] != '\0') 102 pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname); 103 else 104 pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d"); 105 ret = ioctl(fd, TUNSETIFF, (void *) &ifr); 106 if (ret != 0) { 107 if (ifname[0] != '\0') { 108 error_setg_errno(errp, errno, "could not configure %s (%s)", 109 PATH_NET_TUN, ifr.ifr_name); 110 } else { 111 error_setg_errno(errp, errno, "could not configure %s", 112 PATH_NET_TUN); 113 } 114 close(fd); 115 return -1; 116 } 117 pstrcpy(ifname, ifname_size, ifr.ifr_name); 118 fcntl(fd, F_SETFL, O_NONBLOCK); 119 return fd; 120 } 121 122 /* sndbuf implements a kind of flow control for tap. 123 * Unfortunately when it's enabled, and packets are sent 124 * to other guests on the same host, the receiver 125 * can lock up the transmitter indefinitely. 126 * 127 * To avoid packet loss, sndbuf should be set to a value lower than the tx 128 * queue capacity of any destination network interface. 129 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is 130 * a good value, given a 1500 byte MTU. 131 */ 132 #define TAP_DEFAULT_SNDBUF 0 133 134 void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) 135 { 136 int sndbuf; 137 138 sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF : 139 tap->sndbuf > INT_MAX ? INT_MAX : 140 tap->sndbuf; 141 142 if (!sndbuf) { 143 sndbuf = INT_MAX; 144 } 145 146 if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) { 147 error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed"); 148 } 149 } 150 151 int tap_probe_vnet_hdr(int fd) 152 { 153 struct ifreq ifr; 154 155 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 156 error_report("TUNGETIFF ioctl() failed: %s", strerror(errno)); 157 return 0; 158 } 159 160 return ifr.ifr_flags & IFF_VNET_HDR; 161 } 162 163 int tap_probe_has_ufo(int fd) 164 { 165 unsigned offload; 166 167 offload = TUN_F_CSUM | TUN_F_UFO; 168 169 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) 170 return 0; 171 172 return 1; 173 } 174 175 /* Verify that we can assign given length */ 176 int tap_probe_vnet_hdr_len(int fd, int len) 177 { 178 int orig; 179 if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) { 180 return 0; 181 } 182 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 183 return 0; 184 } 185 /* Restore original length: we can't handle failure. */ 186 if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) { 187 fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 188 strerror(errno)); 189 abort(); 190 return -errno; 191 } 192 return 1; 193 } 194 195 void tap_fd_set_vnet_hdr_len(int fd, int len) 196 { 197 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 198 fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 199 strerror(errno)); 200 abort(); 201 } 202 } 203 204 int tap_fd_set_vnet_le(int fd, int is_le) 205 { 206 int arg = is_le ? 1 : 0; 207 208 if (!ioctl(fd, TUNSETVNETLE, &arg)) { 209 return 0; 210 } 211 212 /* Check if our kernel supports TUNSETVNETLE */ 213 if (errno == EINVAL) { 214 return -errno; 215 } 216 217 error_report("TUNSETVNETLE ioctl() failed: %s.", strerror(errno)); 218 abort(); 219 } 220 221 int tap_fd_set_vnet_be(int fd, int is_be) 222 { 223 int arg = is_be ? 1 : 0; 224 225 if (!ioctl(fd, TUNSETVNETBE, &arg)) { 226 return 0; 227 } 228 229 /* Check if our kernel supports TUNSETVNETBE */ 230 if (errno == EINVAL) { 231 return -errno; 232 } 233 234 error_report("TUNSETVNETBE ioctl() failed: %s.", strerror(errno)); 235 abort(); 236 } 237 238 void tap_fd_set_offload(int fd, int csum, int tso4, 239 int tso6, int ecn, int ufo) 240 { 241 unsigned int offload = 0; 242 243 /* Check if our kernel supports TUNSETOFFLOAD */ 244 if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) { 245 return; 246 } 247 248 if (csum) { 249 offload |= TUN_F_CSUM; 250 if (tso4) 251 offload |= TUN_F_TSO4; 252 if (tso6) 253 offload |= TUN_F_TSO6; 254 if ((tso4 || tso6) && ecn) 255 offload |= TUN_F_TSO_ECN; 256 if (ufo) 257 offload |= TUN_F_UFO; 258 } 259 260 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 261 offload &= ~TUN_F_UFO; 262 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 263 fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", 264 strerror(errno)); 265 } 266 } 267 } 268 269 /* Enable a specific queue of tap. */ 270 int tap_fd_enable(int fd) 271 { 272 struct ifreq ifr; 273 int ret; 274 275 memset(&ifr, 0, sizeof(ifr)); 276 277 ifr.ifr_flags = IFF_ATTACH_QUEUE; 278 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr); 279 280 if (ret != 0) { 281 error_report("could not enable queue"); 282 } 283 284 return ret; 285 } 286 287 /* Disable a specific queue of tap/ */ 288 int tap_fd_disable(int fd) 289 { 290 struct ifreq ifr; 291 int ret; 292 293 memset(&ifr, 0, sizeof(ifr)); 294 295 ifr.ifr_flags = IFF_DETACH_QUEUE; 296 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr); 297 298 if (ret != 0) { 299 error_report("could not disable queue"); 300 } 301 302 return ret; 303 } 304 305 int tap_fd_get_ifname(int fd, char *ifname) 306 { 307 struct ifreq ifr; 308 309 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 310 error_report("TUNGETIFF ioctl() failed: %s", 311 strerror(errno)); 312 return -1; 313 } 314 315 pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name); 316 return 0; 317 } 318