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