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