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 "tap_int.h" 28 #include "tap-linux.h" 29 #include "net/tap.h" 30 31 #include <net/if.h> 32 #include <sys/ioctl.h> 33 34 #include "qapi/error.h" 35 #include "qemu/error-report.h" 36 #include "qemu/cutils.h" 37 38 #define PATH_NET_TUN "/dev/net/tun" 39 40 int tap_open(char *ifname, int ifname_size, int *vnet_hdr, 41 int vnet_hdr_required, int mq_required, Error **errp) 42 { 43 struct ifreq ifr; 44 int fd, ret; 45 int len = sizeof(struct virtio_net_hdr); 46 unsigned int features; 47 48 49 ret = if_nametoindex(ifname); 50 if (ret) { 51 g_autofree char *file = g_strdup_printf("/dev/tap%d", ret); 52 fd = open(file, O_RDWR); 53 } else { 54 fd = -1; 55 } 56 57 if (fd < 0) { 58 fd = RETRY_ON_EINTR(open(PATH_NET_TUN, O_RDWR)); 59 if (fd < 0) { 60 error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN); 61 return -1; 62 } 63 } 64 memset(&ifr, 0, sizeof(ifr)); 65 ifr.ifr_flags = IFF_TAP | IFF_NO_PI; 66 67 if (ioctl(fd, TUNGETFEATURES, &features) == -1) { 68 warn_report("TUNGETFEATURES failed: %s", strerror(errno)); 69 features = 0; 70 } 71 72 if (features & IFF_ONE_QUEUE) { 73 ifr.ifr_flags |= IFF_ONE_QUEUE; 74 } 75 76 if (*vnet_hdr) { 77 if (features & IFF_VNET_HDR) { 78 *vnet_hdr = 1; 79 ifr.ifr_flags |= IFF_VNET_HDR; 80 } else { 81 *vnet_hdr = 0; 82 } 83 84 if (vnet_hdr_required && !*vnet_hdr) { 85 error_setg(errp, "vnet_hdr=1 requested, but no kernel " 86 "support for IFF_VNET_HDR available"); 87 close(fd); 88 return -1; 89 } 90 /* 91 * Make sure vnet header size has the default value: for a persistent 92 * tap it might have been modified e.g. by another instance of qemu. 93 * Ignore errors since old kernels do not support this ioctl: in this 94 * case the header size implicitly has the correct value. 95 */ 96 ioctl(fd, TUNSETVNETHDRSZ, &len); 97 } 98 99 if (mq_required) { 100 if (!(features & IFF_MULTI_QUEUE)) { 101 error_setg(errp, "multiqueue required, but no kernel " 102 "support for IFF_MULTI_QUEUE available"); 103 close(fd); 104 return -1; 105 } else { 106 ifr.ifr_flags |= IFF_MULTI_QUEUE; 107 } 108 } 109 110 if (ifname[0] != '\0') 111 pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname); 112 else 113 pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d"); 114 ret = ioctl(fd, TUNSETIFF, (void *) &ifr); 115 if (ret != 0) { 116 if (ifname[0] != '\0') { 117 error_setg_errno(errp, errno, "could not configure %s (%s)", 118 PATH_NET_TUN, ifr.ifr_name); 119 } else { 120 error_setg_errno(errp, errno, "could not configure %s", 121 PATH_NET_TUN); 122 } 123 close(fd); 124 return -1; 125 } 126 pstrcpy(ifname, ifname_size, ifr.ifr_name); 127 g_unix_set_fd_nonblocking(fd, true, NULL); 128 return fd; 129 } 130 131 /* sndbuf implements a kind of flow control for tap. 132 * Unfortunately when it's enabled, and packets are sent 133 * to other guests on the same host, the receiver 134 * can lock up the transmitter indefinitely. 135 * 136 * To avoid packet loss, sndbuf should be set to a value lower than the tx 137 * queue capacity of any destination network interface. 138 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is 139 * a good value, given a 1500 byte MTU. 140 */ 141 #define TAP_DEFAULT_SNDBUF 0 142 143 void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) 144 { 145 int sndbuf; 146 147 sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF : 148 tap->sndbuf > INT_MAX ? INT_MAX : 149 tap->sndbuf; 150 151 if (!sndbuf) { 152 sndbuf = INT_MAX; 153 } 154 155 if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) { 156 error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed"); 157 } 158 } 159 160 int tap_probe_vnet_hdr(int fd, Error **errp) 161 { 162 struct ifreq ifr; 163 memset(&ifr, 0, sizeof(ifr)); 164 165 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 166 /* TUNGETIFF is available since kernel v2.6.27 */ 167 error_setg_errno(errp, errno, 168 "Unable to query TUNGETIFF on FD %d", fd); 169 return -1; 170 } 171 172 return ifr.ifr_flags & IFF_VNET_HDR; 173 } 174 175 int tap_probe_has_ufo(int fd) 176 { 177 unsigned offload; 178 179 offload = TUN_F_CSUM | TUN_F_UFO; 180 181 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) 182 return 0; 183 184 return 1; 185 } 186 187 int tap_probe_has_uso(int fd) 188 { 189 unsigned offload; 190 191 offload = TUN_F_CSUM | TUN_F_USO4 | TUN_F_USO6; 192 193 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) { 194 return 0; 195 } 196 return 1; 197 } 198 199 void tap_fd_set_vnet_hdr_len(int fd, int len) 200 { 201 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 202 fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 203 strerror(errno)); 204 abort(); 205 } 206 } 207 208 int tap_fd_set_vnet_le(int fd, int is_le) 209 { 210 int arg = is_le ? 1 : 0; 211 212 if (!ioctl(fd, TUNSETVNETLE, &arg)) { 213 return 0; 214 } 215 216 /* Check if our kernel supports TUNSETVNETLE */ 217 if (errno == EINVAL) { 218 return -errno; 219 } 220 221 error_report("TUNSETVNETLE ioctl() failed: %s.", strerror(errno)); 222 abort(); 223 } 224 225 int tap_fd_set_vnet_be(int fd, int is_be) 226 { 227 int arg = is_be ? 1 : 0; 228 229 if (!ioctl(fd, TUNSETVNETBE, &arg)) { 230 return 0; 231 } 232 233 /* Check if our kernel supports TUNSETVNETBE */ 234 if (errno == EINVAL) { 235 return -errno; 236 } 237 238 error_report("TUNSETVNETBE ioctl() failed: %s.", strerror(errno)); 239 abort(); 240 } 241 242 void tap_fd_set_offload(int fd, int csum, int tso4, 243 int tso6, int ecn, int ufo, int uso4, int uso6) 244 { 245 unsigned int offload = 0; 246 247 /* Check if our kernel supports TUNSETOFFLOAD */ 248 if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) { 249 return; 250 } 251 252 if (csum) { 253 offload |= TUN_F_CSUM; 254 if (tso4) 255 offload |= TUN_F_TSO4; 256 if (tso6) 257 offload |= TUN_F_TSO6; 258 if ((tso4 || tso6) && ecn) 259 offload |= TUN_F_TSO_ECN; 260 if (ufo) 261 offload |= TUN_F_UFO; 262 if (uso4) { 263 offload |= TUN_F_USO4; 264 } 265 if (uso6) { 266 offload |= TUN_F_USO6; 267 } 268 } 269 270 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 271 offload &= ~(TUN_F_USO4 | TUN_F_USO6); 272 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 273 offload &= ~TUN_F_UFO; 274 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 275 fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", 276 strerror(errno)); 277 } 278 } 279 } 280 } 281 282 /* Enable a specific queue of tap. */ 283 int tap_fd_enable(int fd) 284 { 285 struct ifreq ifr; 286 int ret; 287 288 memset(&ifr, 0, sizeof(ifr)); 289 290 ifr.ifr_flags = IFF_ATTACH_QUEUE; 291 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr); 292 293 if (ret != 0) { 294 error_report("could not enable queue"); 295 } 296 297 return ret; 298 } 299 300 /* Disable a specific queue of tap/ */ 301 int tap_fd_disable(int fd) 302 { 303 struct ifreq ifr; 304 int ret; 305 306 memset(&ifr, 0, sizeof(ifr)); 307 308 ifr.ifr_flags = IFF_DETACH_QUEUE; 309 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr); 310 311 if (ret != 0) { 312 error_report("could not disable queue"); 313 } 314 315 return ret; 316 } 317 318 int tap_fd_get_ifname(int fd, char *ifname) 319 { 320 struct ifreq ifr; 321 322 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 323 error_report("TUNGETIFF ioctl() failed: %s", 324 strerror(errno)); 325 return -1; 326 } 327 328 pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name); 329 return 0; 330 } 331 332 int tap_fd_set_steering_ebpf(int fd, int prog_fd) 333 { 334 if (ioctl(fd, TUNSETSTEERINGEBPF, (void *) &prog_fd) != 0) { 335 error_report("Issue while setting TUNSETSTEERINGEBPF:" 336 " %s with fd: %d, prog_fd: %d", 337 strerror(errno), fd, prog_fd); 338 339 return -1; 340 } 341 342 return 0; 343 } 344