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 "tap_int.h" 27 #include "tap-linux.h" 28 #include "net/tap.h" 29 30 #include <net/if.h> 31 #include <sys/ioctl.h> 32 33 #include "sysemu/sysemu.h" 34 #include "qemu-common.h" 35 #include "qemu/error-report.h" 36 37 #define PATH_NET_TUN "/dev/net/tun" 38 39 int tap_open(char *ifname, int ifname_size, int *vnet_hdr, 40 int vnet_hdr_required, int mq_required, Error **errp) 41 { 42 struct ifreq ifr; 43 int fd, ret; 44 int len = sizeof(struct virtio_net_hdr); 45 unsigned int features; 46 47 TFR(fd = open(PATH_NET_TUN, O_RDWR)); 48 if (fd < 0) { 49 error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN); 50 return -1; 51 } 52 memset(&ifr, 0, sizeof(ifr)); 53 ifr.ifr_flags = IFF_TAP | IFF_NO_PI; 54 55 if (ioctl(fd, TUNGETFEATURES, &features) == -1) { 56 error_report("warning: TUNGETFEATURES failed: %s", strerror(errno)); 57 features = 0; 58 } 59 60 if (features & IFF_ONE_QUEUE) { 61 ifr.ifr_flags |= IFF_ONE_QUEUE; 62 } 63 64 if (*vnet_hdr) { 65 if (features & IFF_VNET_HDR) { 66 *vnet_hdr = 1; 67 ifr.ifr_flags |= IFF_VNET_HDR; 68 } else { 69 *vnet_hdr = 0; 70 } 71 72 if (vnet_hdr_required && !*vnet_hdr) { 73 error_setg(errp, "vnet_hdr=1 requested, but no kernel " 74 "support for IFF_VNET_HDR available"); 75 close(fd); 76 return -1; 77 } 78 /* 79 * Make sure vnet header size has the default value: for a persistent 80 * tap it might have been modified e.g. by another instance of qemu. 81 * Ignore errors since old kernels do not support this ioctl: in this 82 * case the header size implicitly has the correct value. 83 */ 84 ioctl(fd, TUNSETVNETHDRSZ, &len); 85 } 86 87 if (mq_required) { 88 if (!(features & IFF_MULTI_QUEUE)) { 89 error_setg(errp, "multiqueue required, but no kernel " 90 "support for IFF_MULTI_QUEUE available"); 91 close(fd); 92 return -1; 93 } else { 94 ifr.ifr_flags |= IFF_MULTI_QUEUE; 95 } 96 } 97 98 if (ifname[0] != '\0') 99 pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname); 100 else 101 pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d"); 102 ret = ioctl(fd, TUNSETIFF, (void *) &ifr); 103 if (ret != 0) { 104 if (ifname[0] != '\0') { 105 error_setg_errno(errp, errno, "could not configure %s (%s)", 106 PATH_NET_TUN, ifr.ifr_name); 107 } else { 108 error_setg_errno(errp, errno, "could not configure %s", 109 PATH_NET_TUN); 110 } 111 close(fd); 112 return -1; 113 } 114 pstrcpy(ifname, ifname_size, ifr.ifr_name); 115 fcntl(fd, F_SETFL, O_NONBLOCK); 116 return fd; 117 } 118 119 /* sndbuf implements a kind of flow control for tap. 120 * Unfortunately when it's enabled, and packets are sent 121 * to other guests on the same host, the receiver 122 * can lock up the transmitter indefinitely. 123 * 124 * To avoid packet loss, sndbuf should be set to a value lower than the tx 125 * queue capacity of any destination network interface. 126 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is 127 * a good value, given a 1500 byte MTU. 128 */ 129 #define TAP_DEFAULT_SNDBUF 0 130 131 void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) 132 { 133 int sndbuf; 134 135 sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF : 136 tap->sndbuf > INT_MAX ? INT_MAX : 137 tap->sndbuf; 138 139 if (!sndbuf) { 140 sndbuf = INT_MAX; 141 } 142 143 if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) { 144 error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed"); 145 } 146 } 147 148 int tap_probe_vnet_hdr(int fd) 149 { 150 struct ifreq ifr; 151 152 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 153 error_report("TUNGETIFF ioctl() failed: %s", strerror(errno)); 154 return 0; 155 } 156 157 return ifr.ifr_flags & IFF_VNET_HDR; 158 } 159 160 int tap_probe_has_ufo(int fd) 161 { 162 unsigned offload; 163 164 offload = TUN_F_CSUM | TUN_F_UFO; 165 166 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) 167 return 0; 168 169 return 1; 170 } 171 172 /* Verify that we can assign given length */ 173 int tap_probe_vnet_hdr_len(int fd, int len) 174 { 175 int orig; 176 if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) { 177 return 0; 178 } 179 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 180 return 0; 181 } 182 /* Restore original length: we can't handle failure. */ 183 if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) { 184 fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 185 strerror(errno)); 186 abort(); 187 return -errno; 188 } 189 return 1; 190 } 191 192 void tap_fd_set_vnet_hdr_len(int fd, int len) 193 { 194 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 195 fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 196 strerror(errno)); 197 abort(); 198 } 199 } 200 201 int tap_fd_set_vnet_le(int fd, int is_le) 202 { 203 int arg = is_le ? 1 : 0; 204 205 if (!ioctl(fd, TUNSETVNETLE, &arg)) { 206 return 0; 207 } 208 209 /* Check if our kernel supports TUNSETVNETLE */ 210 if (errno == EINVAL) { 211 return -errno; 212 } 213 214 error_report("TUNSETVNETLE ioctl() failed: %s.\n", strerror(errno)); 215 abort(); 216 } 217 218 int tap_fd_set_vnet_be(int fd, int is_be) 219 { 220 int arg = is_be ? 1 : 0; 221 222 if (!ioctl(fd, TUNSETVNETBE, &arg)) { 223 return 0; 224 } 225 226 /* Check if our kernel supports TUNSETVNETBE */ 227 if (errno == EINVAL) { 228 return -errno; 229 } 230 231 error_report("TUNSETVNETBE ioctl() failed: %s.\n", strerror(errno)); 232 abort(); 233 } 234 235 void tap_fd_set_offload(int fd, int csum, int tso4, 236 int tso6, int ecn, int ufo) 237 { 238 unsigned int offload = 0; 239 240 /* Check if our kernel supports TUNSETOFFLOAD */ 241 if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) { 242 return; 243 } 244 245 if (csum) { 246 offload |= TUN_F_CSUM; 247 if (tso4) 248 offload |= TUN_F_TSO4; 249 if (tso6) 250 offload |= TUN_F_TSO6; 251 if ((tso4 || tso6) && ecn) 252 offload |= TUN_F_TSO_ECN; 253 if (ufo) 254 offload |= TUN_F_UFO; 255 } 256 257 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 258 offload &= ~TUN_F_UFO; 259 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 260 fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", 261 strerror(errno)); 262 } 263 } 264 } 265 266 /* Enable a specific queue of tap. */ 267 int tap_fd_enable(int fd) 268 { 269 struct ifreq ifr; 270 int ret; 271 272 memset(&ifr, 0, sizeof(ifr)); 273 274 ifr.ifr_flags = IFF_ATTACH_QUEUE; 275 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr); 276 277 if (ret != 0) { 278 error_report("could not enable queue"); 279 } 280 281 return ret; 282 } 283 284 /* Disable a specific queue of tap/ */ 285 int tap_fd_disable(int fd) 286 { 287 struct ifreq ifr; 288 int ret; 289 290 memset(&ifr, 0, sizeof(ifr)); 291 292 ifr.ifr_flags = IFF_DETACH_QUEUE; 293 ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr); 294 295 if (ret != 0) { 296 error_report("could not disable queue"); 297 } 298 299 return ret; 300 } 301 302 int tap_fd_get_ifname(int fd, char *ifname) 303 { 304 struct ifreq ifr; 305 306 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 307 error_report("TUNGETIFF ioctl() failed: %s", 308 strerror(errno)); 309 return -1; 310 } 311 312 pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name); 313 return 0; 314 } 315