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 "net/tap.h" 27 #include "net/tap-linux.h" 28 29 #include <net/if.h> 30 #include <sys/ioctl.h> 31 32 #include "sysemu.h" 33 #include "qemu-common.h" 34 #include "qemu-error.h" 35 36 #define PATH_NET_TUN "/dev/net/tun" 37 38 int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required) 39 { 40 struct ifreq ifr; 41 int fd, ret; 42 43 TFR(fd = open(PATH_NET_TUN, O_RDWR)); 44 if (fd < 0) { 45 error_report("could not open %s: %m", PATH_NET_TUN); 46 return -1; 47 } 48 memset(&ifr, 0, sizeof(ifr)); 49 ifr.ifr_flags = IFF_TAP | IFF_NO_PI; 50 51 if (*vnet_hdr) { 52 unsigned int features; 53 54 if (ioctl(fd, TUNGETFEATURES, &features) == 0 && 55 features & IFF_VNET_HDR) { 56 *vnet_hdr = 1; 57 ifr.ifr_flags |= IFF_VNET_HDR; 58 } else { 59 *vnet_hdr = 0; 60 } 61 62 if (vnet_hdr_required && !*vnet_hdr) { 63 error_report("vnet_hdr=1 requested, but no kernel " 64 "support for IFF_VNET_HDR available"); 65 close(fd); 66 return -1; 67 } 68 } 69 70 if (ifname[0] != '\0') 71 pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname); 72 else 73 pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d"); 74 ret = ioctl(fd, TUNSETIFF, (void *) &ifr); 75 if (ret != 0) { 76 if (ifname[0] != '\0') { 77 error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name); 78 } else { 79 error_report("could not configure %s: %m", PATH_NET_TUN); 80 } 81 close(fd); 82 return -1; 83 } 84 pstrcpy(ifname, ifname_size, ifr.ifr_name); 85 fcntl(fd, F_SETFL, O_NONBLOCK); 86 return fd; 87 } 88 89 /* sndbuf implements a kind of flow control for tap. 90 * Unfortunately when it's enabled, and packets are sent 91 * to other guests on the same host, the receiver 92 * can lock up the transmitter indefinitely. 93 * 94 * To avoid packet loss, sndbuf should be set to a value lower than the tx 95 * queue capacity of any destination network interface. 96 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is 97 * a good value, given a 1500 byte MTU. 98 */ 99 #define TAP_DEFAULT_SNDBUF 0 100 101 int tap_set_sndbuf(int fd, const NetdevTapOptions *tap) 102 { 103 int sndbuf; 104 105 sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF : 106 tap->sndbuf > INT_MAX ? INT_MAX : 107 tap->sndbuf; 108 109 if (!sndbuf) { 110 sndbuf = INT_MAX; 111 } 112 113 if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) { 114 error_report("TUNSETSNDBUF ioctl failed: %s", strerror(errno)); 115 return -1; 116 } 117 return 0; 118 } 119 120 int tap_probe_vnet_hdr(int fd) 121 { 122 struct ifreq ifr; 123 124 if (ioctl(fd, TUNGETIFF, &ifr) != 0) { 125 error_report("TUNGETIFF ioctl() failed: %s", strerror(errno)); 126 return 0; 127 } 128 129 return ifr.ifr_flags & IFF_VNET_HDR; 130 } 131 132 int tap_probe_has_ufo(int fd) 133 { 134 unsigned offload; 135 136 offload = TUN_F_CSUM | TUN_F_UFO; 137 138 if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) 139 return 0; 140 141 return 1; 142 } 143 144 /* Verify that we can assign given length */ 145 int tap_probe_vnet_hdr_len(int fd, int len) 146 { 147 int orig; 148 if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) { 149 return 0; 150 } 151 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 152 return 0; 153 } 154 /* Restore original length: we can't handle failure. */ 155 if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) { 156 fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 157 strerror(errno)); 158 assert(0); 159 return -errno; 160 } 161 return 1; 162 } 163 164 void tap_fd_set_vnet_hdr_len(int fd, int len) 165 { 166 if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { 167 fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n", 168 strerror(errno)); 169 assert(0); 170 } 171 } 172 173 void tap_fd_set_offload(int fd, int csum, int tso4, 174 int tso6, int ecn, int ufo) 175 { 176 unsigned int offload = 0; 177 178 /* Check if our kernel supports TUNSETOFFLOAD */ 179 if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) { 180 return; 181 } 182 183 if (csum) { 184 offload |= TUN_F_CSUM; 185 if (tso4) 186 offload |= TUN_F_TSO4; 187 if (tso6) 188 offload |= TUN_F_TSO6; 189 if ((tso4 || tso6) && ecn) 190 offload |= TUN_F_TSO_ECN; 191 if (ufo) 192 offload |= TUN_F_UFO; 193 } 194 195 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 196 offload &= ~TUN_F_UFO; 197 if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { 198 fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", 199 strerror(errno)); 200 } 201 } 202 } 203