/* * QEMU System Emulator * * Copyright (c) 2003-2008 Fabrice Bellard * Copyright (c) 2009 Red Hat, Inc. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "net/tap.h" #include "net/tap-linux.h" #include <net/if.h> #include <sys/ioctl.h> #include "sysemu.h" #include "qemu-common.h" #include "qemu-error.h" #define PATH_NET_TUN "/dev/net/tun" int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required) { struct ifreq ifr; int fd, ret; TFR(fd = open(PATH_NET_TUN, O_RDWR)); if (fd < 0) { error_report("could not open %s: %m", PATH_NET_TUN); return -1; } memset(&ifr, 0, sizeof(ifr)); ifr.ifr_flags = IFF_TAP | IFF_NO_PI; if (*vnet_hdr) { unsigned int features; if (ioctl(fd, TUNGETFEATURES, &features) == 0 && features & IFF_VNET_HDR) { *vnet_hdr = 1; ifr.ifr_flags |= IFF_VNET_HDR; } else { *vnet_hdr = 0; } if (vnet_hdr_required && !*vnet_hdr) { error_report("vnet_hdr=1 requested, but no kernel " "support for IFF_VNET_HDR available"); close(fd); return -1; } } if (ifname[0] != '\0') pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname); else pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d"); ret = ioctl(fd, TUNSETIFF, (void *) &ifr); if (ret != 0) { if (ifname[0] != '\0') { error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name); } else { error_report("could not configure %s: %m", PATH_NET_TUN); } close(fd); return -1; } pstrcpy(ifname, ifname_size, ifr.ifr_name); fcntl(fd, F_SETFL, O_NONBLOCK); return fd; } /* sndbuf implements a kind of flow control for tap. * Unfortunately when it's enabled, and packets are sent * to other guests on the same host, the receiver * can lock up the transmitter indefinitely. * * To avoid packet loss, sndbuf should be set to a value lower than the tx * queue capacity of any destination network interface. * Ethernet NICs generally have txqueuelen=1000, so 1Mb is * a good value, given a 1500 byte MTU. */ #define TAP_DEFAULT_SNDBUF 0 int tap_set_sndbuf(int fd, const NetdevTapOptions *tap) { int sndbuf; sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF : tap->sndbuf > INT_MAX ? INT_MAX : tap->sndbuf; if (!sndbuf) { sndbuf = INT_MAX; } if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) { error_report("TUNSETSNDBUF ioctl failed: %s", strerror(errno)); return -1; } return 0; } int tap_probe_vnet_hdr(int fd) { struct ifreq ifr; if (ioctl(fd, TUNGETIFF, &ifr) != 0) { error_report("TUNGETIFF ioctl() failed: %s", strerror(errno)); return 0; } return ifr.ifr_flags & IFF_VNET_HDR; } int tap_probe_has_ufo(int fd) { unsigned offload; offload = TUN_F_CSUM | TUN_F_UFO; if (ioctl(fd, TUNSETOFFLOAD, offload) < 0) return 0; return 1; } /* Verify that we can assign given length */ int tap_probe_vnet_hdr_len(int fd, int len) { int orig; if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) { return 0; } if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { return 0; } /* Restore original length: we can't handle failure. */ if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) { fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n", strerror(errno)); assert(0); return -errno; } return 1; } void tap_fd_set_vnet_hdr_len(int fd, int len) { if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) { fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n", strerror(errno)); assert(0); } } void tap_fd_set_offload(int fd, int csum, int tso4, int tso6, int ecn, int ufo) { unsigned int offload = 0; /* Check if our kernel supports TUNSETOFFLOAD */ if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) { return; } if (csum) { offload |= TUN_F_CSUM; if (tso4) offload |= TUN_F_TSO4; if (tso6) offload |= TUN_F_TSO6; if ((tso4 || tso6) && ecn) offload |= TUN_F_TSO_ECN; if (ufo) offload |= TUN_F_UFO; } if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { offload &= ~TUN_F_UFO; if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", strerror(errno)); } } }