// SPDX-License-Identifier: AGPL-3.0-or-later /* PASST - Plug A Simple Socket Transport * for qemu/UNIX domain socket mode * * PASTA - Pack A Subtle Tap Abstraction * for network namespace/tap device mode * * tap.c - Functions to communicate with guest- or namespace-facing interface * * Copyright (c) 2020-2021 Red Hat GmbH * Author: Stefano Brivio * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "checksum.h" #include "util.h" #include "passt.h" #include "arp.h" #include "dhcp.h" #include "ndp.h" #include "dhcpv6.h" #include "pcap.h" #include "netlink.h" #include "pasta.h" #include "packet.h" #include "tap.h" #include "log.h" /* IPv4 (plus ARP) and IPv6 message batches from tap/guest to IP handlers */ static PACKET_POOL_NOINIT(pool_tap4, TAP_MSGS, pkt_buf); static PACKET_POOL_NOINIT(pool_tap6, TAP_MSGS, pkt_buf); #define TAP_SEQS 128 /* Different L4 tuples in one batch */ /** * tap_send() - Send frame, with qemu socket header if needed * @c: Execution context * @data: Packet buffer * @len: Total L2 packet length * * Return: return code from send() or write() */ int tap_send(const struct ctx *c, const void *data, size_t len) { pcap(data, len); if (c->mode == MODE_PASST) { int flags = MSG_NOSIGNAL | MSG_DONTWAIT; uint32_t vnet_len = htonl(len); if (send(c->fd_tap, &vnet_len, 4, flags) < 0) return -1; return send(c->fd_tap, data, len, flags); } return write(c->fd_tap, (char *)data, len); } /** * tap_ip4_daddr() - Normal IPv4 destination address for inbound packets * @c: Execution context * * Return: IPv4 address, network order */ struct in_addr tap_ip4_daddr(const struct ctx *c) { return c->ip4.addr_seen; } /** * tap_ip6_daddr() - Normal IPv6 destination address for inbound packets * @c: Execution context * @src: Source address * * Return: pointer to IPv6 address */ const struct in6_addr *tap_ip6_daddr(const struct ctx *c, const struct in6_addr *src) { if (IN6_IS_ADDR_LINKLOCAL(src)) return &c->ip6.addr_ll_seen; return &c->ip6.addr_seen; } /** * tap_push_l2h() - Build an L2 header for an inbound packet * @c: Execution context * @buf: Buffer address at which to generate header * @proto: Ethernet protocol number for L3 * * Return: pointer at which to write the packet's payload */ static void *tap_push_l2h(const struct ctx *c, void *buf, uint16_t proto) { struct ethhdr *eh = (struct ethhdr *)buf; /* TODO: ARP table lookup */ memcpy(eh->h_dest, c->mac_guest, ETH_ALEN); memcpy(eh->h_source, c->mac, ETH_ALEN); eh->h_proto = ntohs(proto); return eh + 1; } /** * tap_push_ip4h() - Build IPv4 header for inbound packet, with checksum * @c: Execution context * @src: IPv4 source address, network order * @dst: IPv4 destination address, network order * @len: L4 payload length * @proto: L4 protocol number * * Return: pointer at which to write the packet's payload */ static void *tap_push_ip4h(char *buf, struct in_addr src, struct in_addr dst, size_t len, uint8_t proto) { struct iphdr *ip4h = (struct iphdr *)buf; ip4h->version = 4; ip4h->ihl = sizeof(struct iphdr) / 4; ip4h->tos = 0; ip4h->tot_len = htons(len + sizeof(*ip4h)); ip4h->id = 0; ip4h->frag_off = 0; ip4h->ttl = 255; ip4h->protocol = proto; ip4h->saddr = src.s_addr; ip4h->daddr = dst.s_addr; csum_ip4_header(ip4h); return ip4h + 1; } /** * tap_udp4_send() - Send UDP over IPv4 packet * @c: Execution context * @src: IPv4 source address * @sport: UDP source port * @dst: IPv4 destination address * @dport: UDP destination port * @in: UDP payload contents (not including UDP header) * @len: UDP payload length (not including UDP header) */ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport, struct in_addr dst, in_port_t dport, const void *in, size_t len) { size_t udplen = len + sizeof(struct udphdr); char buf[USHRT_MAX]; void *ip4h = tap_push_l2h(c, buf, ETH_P_IP); void *uhp = tap_push_ip4h(ip4h, src, dst, udplen, IPPROTO_UDP); struct udphdr *uh = (struct udphdr *)uhp; char *data = (char *)(uh + 1); uh->source = htons(sport); uh->dest = htons(dport); uh->len = htons(udplen); csum_udp4(uh, src, dst, in, len); memcpy(data, in, len); if (tap_send(c, buf, len + (data - buf)) < 0) debug("tap: failed to send %lu bytes (IPv4)", len); } /** * tap_icmp4_send() - Send ICMPv4 packet * @c: Execution context * @src: IPv4 source address * @dst: IPv4 destination address * @in: ICMP packet, including ICMP header * @len: ICMP packet length, including ICMP header */ void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst, void *in, size_t len) { char buf[USHRT_MAX]; void *ip4h = tap_push_l2h(c, buf, ETH_P_IP); char *data = tap_push_ip4h(ip4h, src, dst, len, IPPROTO_ICMP); struct icmphdr *icmp4h = (struct icmphdr *)data; memcpy(data, in, len); csum_icmp4(icmp4h, icmp4h + 1, len - sizeof(*icmp4h)); if (tap_send(c, buf, len + (data - buf)) < 0) debug("tap: failed to send %lu bytes (IPv4)", len); } /** * tap_push_ip6h() - Build IPv6 header for inbound packet * @c: Execution context * @src: IPv6 source address * @dst: IPv6 destination address * @len: L4 payload length * @proto: L4 protocol number * @flow: IPv6 flow identifier * * Return: pointer at which to write the packet's payload */ static void *tap_push_ip6h(char *buf, const struct in6_addr *src, const struct in6_addr *dst, size_t len, uint8_t proto, uint32_t flow) { struct ipv6hdr *ip6h = (struct ipv6hdr *)buf; ip6h->payload_len = htons(len); ip6h->priority = 0; ip6h->version = 6; ip6h->nexthdr = proto; ip6h->hop_limit = 255; ip6h->saddr = *src; ip6h->daddr = *dst; ip6h->flow_lbl[0] = (flow >> 16) & 0xf; ip6h->flow_lbl[1] = (flow >> 8) & 0xff; ip6h->flow_lbl[2] = (flow >> 0) & 0xff; return ip6h + 1; } /** * tap_udp6_send() - Send UDP over IPv6 packet * @c: Execution context * @src: IPv6 source address * @sport: UDP source port * @dst: IPv6 destination address * @dport: UDP destination port * @flow: Flow label * @in: UDP payload contents (not including UDP header) * @len: UDP payload length (not including UDP header) */ void tap_udp6_send(const struct ctx *c, const struct in6_addr *src, in_port_t sport, const struct in6_addr *dst, in_port_t dport, uint32_t flow, const void *in, size_t len) { size_t udplen = len + sizeof(struct udphdr); char buf[USHRT_MAX]; void *ip6h = tap_push_l2h(c, buf, ETH_P_IPV6); void *uhp = tap_push_ip6h(ip6h, src, dst, udplen, IPPROTO_UDP, flow); struct udphdr *uh = (struct udphdr *)uhp; char *data = (char *)(uh + 1); uh->source = htons(sport); uh->dest = htons(dport); uh->len = htons(udplen); csum_udp6(uh, src, dst, in, len); memcpy(data, in, len); if (tap_send(c, buf, len + (data - buf)) < 1) debug("tap: failed to send %lu bytes (IPv6)", len); } /** * tap_icmp6_send() - Send ICMPv6 packet * @c: Execution context * @src: IPv6 source address * @dst: IPv6 destination address * @in: ICMP packet, including ICMP header * @len: ICMP packet length, including ICMP header */ void tap_icmp6_send(const struct ctx *c, const struct in6_addr *src, const struct in6_addr *dst, void *in, size_t len) { char buf[USHRT_MAX]; void *ip6h = tap_push_l2h(c, buf, ETH_P_IPV6); char *data = tap_push_ip6h(ip6h, src, dst, len, IPPROTO_ICMPV6, 0); struct icmp6hdr *icmp6h = (struct icmp6hdr *)data; memcpy(data, in, len); csum_icmp6(icmp6h, src, dst, icmp6h + 1, len - sizeof(*icmp6h)); if (tap_send(c, buf, len + (data - buf)) < 1) debug("tap: failed to send %lu bytes (IPv6)", len); } /** * tap_send_frames_pasta() - Send multiple frames to the pasta tap * @c: Execution context * @iov: Array of buffers, each containing one frame * @n: Number of buffers/frames in @iov * * Returns: number of frames successfully sent * * #syscalls:pasta write */ static size_t tap_send_frames_pasta(struct ctx *c, const struct iovec *iov, size_t n) { size_t i; for (i = 0; i < n; i++) { if (write(c->fd_tap, (char *)iov->iov_base, iov->iov_len) < 0) { debug("tap write: %s", strerror(errno)); if (errno != EAGAIN && errno != EWOULDBLOCK) tap_handler(c, c->fd_tap, EPOLLERR, NULL); i--; } } return n; } /** * tap_send_remainder() - Send remainder of a partially sent frame * @c: Execution context * @iov: Partially sent buffer * @offset: Number of bytes already sent from @iov */ static void tap_send_remainder(const struct ctx *c, const struct iovec *iov, size_t offset) { const char *base = (char *)iov->iov_base; size_t len = iov->iov_len; while (offset < len) { ssize_t sent = send(c->fd_tap, base + offset, len - offset, MSG_NOSIGNAL); if (sent < 0) { err("tap: partial frame send (missing %lu bytes): %s", len - offset, strerror(errno)); return; } offset += sent; } } /** * tap_send_frames_passt() - Send multiple frames to the passt tap * @c: Execution context * @iov: Array of buffers, each containing one frame * @n: Number of buffers/frames in @iov * * Returns: number of frames successfully sent * * #syscalls:passt sendmsg */ static size_t tap_send_frames_passt(const struct ctx *c, const struct iovec *iov, size_t n) { struct msghdr mh = { .msg_iov = (void *)iov, .msg_iovlen = n, }; unsigned int i; ssize_t sent; sent = sendmsg(c->fd_tap, &mh, MSG_NOSIGNAL | MSG_DONTWAIT); if (sent < 0) return 0; /* Check for any partial frames due to short send */ for (i = 0; i < n; i++) { if ((size_t)sent < iov[i].iov_len) break; sent -= iov[i].iov_len; } if (i < n && sent) { /* A partial frame was sent */ tap_send_remainder(c, &iov[i], sent); i++; } return i; } /** * tap_send_frames() - Send out multiple prepared frames * @c: Execution context * @iov: Array of buffers, each containing one frame (with L2 headers) * @n: Number of buffers/frames in @iov */ void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n) { size_t m; if (!n) return; if (c->mode == MODE_PASST) m = tap_send_frames_passt(c, iov, n); else m = tap_send_frames_pasta(c, iov, n); if (m < n) debug("tap: dropped %lu frames of %lu due to short send", n - m, n); pcap_multiple(iov, m, c->mode == MODE_PASST ? sizeof(uint32_t) : 0); } /** * tap_update_mac() - Update tap L2 header with new Ethernet addresses * @taph: Tap headers to update * @eth_d: Ethernet destination address, NULL if unchanged * @eth_s: Ethernet source address, NULL if unchanged */ void tap_update_mac(struct tap_hdr *taph, const unsigned char *eth_d, const unsigned char *eth_s) { if (eth_d) memcpy(taph->eh.h_dest, eth_d, sizeof(taph->eh.h_dest)); if (eth_s) memcpy(taph->eh.h_source, eth_s, sizeof(taph->eh.h_source)); } PACKET_POOL_DECL(pool_l4, UIO_MAXIOV, pkt_buf); /** * struct l4_seq4_t - Message sequence for one protocol handler call, IPv4 * @msgs: Count of messages in sequence * @protocol: Protocol number * @source: Source port * @dest: Destination port * @saddr: Source address * @daddr: Destination address * @msg: Array of messages that can be handled in a single call */ static struct tap4_l4_t { uint8_t protocol; uint16_t source; uint16_t dest; struct in_addr saddr; struct in_addr daddr; struct pool_l4_t p; } tap4_l4[TAP_SEQS /* Arbitrary: TAP_MSGS in theory, so limit in users */]; /** * struct l4_seq6_t - Message sequence for one protocol handler call, IPv6 * @msgs: Count of messages in sequence * @protocol: Protocol number * @source: Source port * @dest: Destination port * @saddr: Source address * @daddr: Destination address * @msg: Array of messages that can be handled in a single call */ static struct tap6_l4_t { uint8_t protocol; uint16_t source; uint16_t dest; struct in6_addr saddr; struct in6_addr daddr; struct pool_l4_t p; } tap6_l4[TAP_SEQS /* Arbitrary: TAP_MSGS in theory, so limit in users */]; /** * tap_packet_debug() - Print debug message for packet(s) from guest/tap * @iph: IPv4 header, can be NULL * @ip6h: IPv6 header, can be NULL * @seq4: Pointer to @struct tap_l4_seq4, can be NULL * @proto6: IPv6 protocol, for IPv6 * @seq6: Pointer to @struct tap_l4_seq6, can be NULL * @count: Count of packets in this sequence */ static void tap_packet_debug(const struct iphdr *iph, const struct ipv6hdr *ip6h, const struct tap4_l4_t *seq4, uint8_t proto6, const struct tap6_l4_t *seq6, int count) { char buf6s[INET6_ADDRSTRLEN], buf6d[INET6_ADDRSTRLEN]; char buf4s[INET_ADDRSTRLEN], buf4d[INET_ADDRSTRLEN]; uint8_t proto = 0; if (iph || seq4) { if (iph) { inet_ntop(AF_INET, &iph->saddr, buf4s, sizeof(buf4s)); inet_ntop(AF_INET, &iph->daddr, buf4d, sizeof(buf4d)); proto = iph->protocol; } else { inet_ntop(AF_INET, &seq4->saddr, buf4s, sizeof(buf4s)); inet_ntop(AF_INET, &seq4->daddr, buf4d, sizeof(buf4d)); proto = seq4->protocol; } } else { inet_ntop(AF_INET6, ip6h ? &ip6h->saddr : &seq6->saddr, buf6s, sizeof(buf6s)); inet_ntop(AF_INET6, ip6h ? &ip6h->daddr : &seq6->daddr, buf6d, sizeof(buf6d)); proto = proto6; } if (proto == IPPROTO_TCP || proto == IPPROTO_UDP) { trace("tap: protocol %i, %s%s%s:%i -> %s%s%s:%i (%i packet%s)", proto, seq4 ? "" : "[", seq4 ? buf4s : buf6s, seq4 ? "" : "]", ntohs(seq4 ? seq4->source : seq6->source), seq4 ? "" : "[", seq4 ? buf4d : buf6d, seq4 ? "" : "]", ntohs(seq4 ? seq4->dest : seq6->dest), count, count == 1 ? "" : "s"); } else { trace("tap: protocol %i, %s -> %s (%i packet%s)", proto, iph ? buf4s : buf6s, iph ? buf4d : buf6d, count, count == 1 ? "" : "s"); } } /** * tap4_handler() - IPv4 and ARP packet handler for tap file descriptor * @c: Execution context * @in: Ingress packet pool, packets with Ethernet headers * @now: Current timestamp * * Return: count of packets consumed by handlers */ static int tap4_handler(struct ctx *c, const struct pool *in, const struct timespec *now) { unsigned int i, j, seq_count; struct tap4_l4_t *seq; if (!c->ifi4 || !in->count) return in->count; i = 0; resume: for (seq_count = 0, seq = NULL; i < in->count; i++) { size_t l2_len, l3_len, hlen, l4_len; struct ethhdr *eh; struct iphdr *iph; struct udphdr *uh; char *l4h; packet_get(in, i, 0, 0, &l2_len); eh = packet_get(in, i, 0, sizeof(*eh), &l3_len); if (!eh) continue; if (ntohs(eh->h_proto) == ETH_P_ARP) { PACKET_POOL_P(pkt, 1, in->buf, sizeof(pkt_buf)); packet_add(pkt, l2_len, (char *)eh); arp(c, pkt); continue; } iph = packet_get(in, i, sizeof(*eh), sizeof(*iph), NULL); if (!iph) continue; hlen = iph->ihl * 4UL; if (hlen < sizeof(*iph) || htons(iph->tot_len) != l3_len || hlen > l3_len) continue; l4_len = l3_len - hlen; if (iph->saddr && c->ip4.addr_seen.s_addr != iph->saddr) { c->ip4.addr_seen.s_addr = iph->saddr; proto_update_l2_buf(NULL, NULL, &c->ip4.addr_seen); } l4h = packet_get(in, i, sizeof(*eh) + hlen, l4_len, NULL); if (!l4h) continue; if (iph->protocol == IPPROTO_ICMP) { PACKET_POOL_P(pkt, 1, in->buf, sizeof(pkt_buf)); if (c->no_icmp) continue; tap_packet_debug(iph, NULL, NULL, 0, NULL, 1); packet_add(pkt, l4_len, l4h); icmp_tap_handler(c, AF_INET, &iph->daddr, pkt, now); continue; } uh = packet_get(in, i, sizeof(*eh) + hlen, sizeof(*uh), NULL); if (!uh) continue; if (iph->protocol == IPPROTO_UDP) { PACKET_POOL_P(pkt, 1, in->buf, sizeof(pkt_buf)); packet_add(pkt, l2_len, (char *)eh); if (dhcp(c, pkt)) continue; } if (iph->protocol != IPPROTO_TCP && iph->protocol != IPPROTO_UDP) { tap_packet_debug(iph, NULL, NULL, 0, NULL, 1); continue; } #define L4_MATCH(iph, uh, seq) \ (seq->protocol == iph->protocol && \ seq->source == uh->source && seq->dest == uh->dest && \ seq->saddr.s_addr == iph->saddr && seq->daddr.s_addr == iph->daddr) #define L4_SET(iph, uh, seq) \ do { \ seq->protocol = iph->protocol; \ seq->source = uh->source; \ seq->dest = uh->dest; \ seq->saddr.s_addr = iph->saddr; \ seq->daddr.s_addr = iph->daddr; \ } while (0) if (seq && L4_MATCH(iph, uh, seq) && seq->p.count < TAP_SEQS) goto append; if (seq_count == TAP_SEQS) break; /* Resume after flushing if i < in->count */ for (seq = tap4_l4 + seq_count - 1; seq >= tap4_l4; seq--) { if (L4_MATCH(iph, uh, seq)) { if (seq->p.count >= TAP_SEQS) seq = NULL; break; } } if (!seq || seq < tap4_l4) { seq = tap4_l4 + seq_count++; L4_SET(iph, uh, seq); pool_flush((struct pool *)&seq->p); } #undef L4_MATCH #undef L4_SET append: packet_add((struct pool *)&seq->p, l4_len, l4h); } for (j = 0, seq = tap4_l4; j < seq_count; j++, seq++) { struct pool *p = (struct pool *)&seq->p; struct in_addr *da = &seq->daddr; size_t n = p->count; tap_packet_debug(NULL, NULL, seq, 0, NULL, n); if (seq->protocol == IPPROTO_TCP) { if (c->no_tcp) continue; while ((n -= tcp_tap_handler(c, AF_INET, da, p, now))); } else if (seq->protocol == IPPROTO_UDP) { if (c->no_udp) continue; while ((n -= udp_tap_handler(c, AF_INET, da, p, now))); } } if (i < in->count) goto resume; return in->count; } /** * tap6_handler() - IPv6 packet handler for tap file descriptor * @c: Execution context * @in: Ingress packet pool, packets with Ethernet headers * @now: Current timestamp * * Return: count of packets consumed by handlers */ static int tap6_handler(struct ctx *c, const struct pool *in, const struct timespec *now) { unsigned int i, j, seq_count = 0; struct tap6_l4_t *seq; if (!c->ifi6 || !in->count) return in->count; i = 0; resume: for (seq_count = 0, seq = NULL; i < in->count; i++) { size_t l4_len, plen, check; struct in6_addr *saddr, *daddr; struct ipv6hdr *ip6h; struct ethhdr *eh; struct udphdr *uh; uint8_t proto; char *l4h; eh = packet_get(in, i, 0, sizeof(*eh), NULL); if (!eh) continue; ip6h = packet_get(in, i, sizeof(*eh), sizeof(*ip6h), &check); if (!ip6h) continue; saddr = &ip6h->saddr; daddr = &ip6h->daddr; plen = ntohs(ip6h->payload_len); if (plen != check) continue; if (!(l4h = ipv6_l4hdr(in, i, sizeof(*eh), &proto, &l4_len))) continue; if (IN6_IS_ADDR_LINKLOCAL(saddr)) { c->ip6.addr_ll_seen = *saddr; if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr_seen)) { c->ip6.addr_seen = *saddr; } } else { c->ip6.addr_seen = *saddr; } if (proto == IPPROTO_ICMPV6) { PACKET_POOL_P(pkt, 1, in->buf, sizeof(pkt_buf)); if (c->no_icmp) continue; if (l4_len < sizeof(struct icmp6hdr)) continue; if (ndp(c, (struct icmp6hdr *)l4h, saddr)) continue; tap_packet_debug(NULL, ip6h, NULL, proto, NULL, 1); packet_add(pkt, l4_len, l4h); icmp_tap_handler(c, AF_INET6, daddr, pkt, now); continue; } if (l4_len < sizeof(*uh)) continue; uh = (struct udphdr *)l4h; if (proto == IPPROTO_UDP) { PACKET_POOL_P(pkt, 1, in->buf, sizeof(pkt_buf)); packet_add(pkt, l4_len, l4h); if (dhcpv6(c, pkt, saddr, daddr)) continue; } *saddr = c->ip6.addr; if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) { tap_packet_debug(NULL, ip6h, NULL, proto, NULL, 1); continue; } #define L4_MATCH(ip6h, proto, uh, seq) \ (seq->protocol == proto && \ seq->source == uh->source && seq->dest == uh->dest && \ IN6_ARE_ADDR_EQUAL(&seq->saddr, saddr) && \ IN6_ARE_ADDR_EQUAL(&seq->daddr, daddr)) #define L4_SET(ip6h, proto, uh, seq) \ do { \ seq->protocol = proto; \ seq->source = uh->source; \ seq->dest = uh->dest; \ seq->saddr = *saddr; \ seq->daddr = *daddr; \ } while (0) if (seq && L4_MATCH(ip6h, proto, uh, seq) && seq->p.count < TAP_SEQS) goto append; if (seq_count == TAP_SEQS) break; /* Resume after flushing if i < in->count */ for (seq = tap6_l4 + seq_count - 1; seq >= tap6_l4; seq--) { if (L4_MATCH(ip6h, proto, uh, seq)) { if (seq->p.count >= TAP_SEQS) seq = NULL; break; } } if (!seq || seq < tap6_l4) { seq = tap6_l4 + seq_count++; L4_SET(ip6h, proto, uh, seq); pool_flush((struct pool *)&seq->p); } #undef L4_MATCH #undef L4_SET append: packet_add((struct pool *)&seq->p, l4_len, l4h); } for (j = 0, seq = tap6_l4; j < seq_count; j++, seq++) { struct pool *p = (struct pool *)&seq->p; struct in6_addr *da = &seq->daddr; size_t n = p->count; tap_packet_debug(NULL, NULL, NULL, seq->protocol, seq, n); if (seq->protocol == IPPROTO_TCP) { if (c->no_tcp) continue; while ((n -= tcp_tap_handler(c, AF_INET6, da, p, now))); } else if (seq->protocol == IPPROTO_UDP) { if (c->no_udp) continue; while ((n -= udp_tap_handler(c, AF_INET6, da, p, now))); } } if (i < in->count) goto resume; return in->count; } /** * tap_handler_passt() - Packet handler for AF_UNIX file descriptor * @c: Execution context * @now: Current timestamp * * Return: -ECONNRESET on receive error, 0 otherwise */ static int tap_handler_passt(struct ctx *c, const struct timespec *now) { struct ethhdr *eh; ssize_t n, rem; char *p; redo: p = pkt_buf; rem = 0; pool_flush(pool_tap4); pool_flush(pool_tap6); n = recv(c->fd_tap, p, TAP_BUF_FILL, MSG_DONTWAIT); if (n < 0) { if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) return 0; epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_tap, NULL); close(c->fd_tap); return -ECONNRESET; } while (n > (ssize_t)sizeof(uint32_t)) { ssize_t len = ntohl(*(uint32_t *)p); p += sizeof(uint32_t); n -= sizeof(uint32_t); /* At most one packet might not fit in a single read, and this * needs to be blocking. */ if (len > n) { rem = recv(c->fd_tap, p + n, len - n, 0); if ((n += rem) != len) return 0; } /* Complete the partial read above before discarding a malformed * frame, otherwise the stream will be inconsistent. */ if (len < (ssize_t)sizeof(*eh) || len > (ssize_t)ETH_MAX_MTU) goto next; pcap(p, len); eh = (struct ethhdr *)p; if (memcmp(c->mac_guest, eh->h_source, ETH_ALEN)) { memcpy(c->mac_guest, eh->h_source, ETH_ALEN); proto_update_l2_buf(c->mac_guest, NULL, NULL); } switch (ntohs(eh->h_proto)) { case ETH_P_ARP: case ETH_P_IP: packet_add(pool_tap4, len, p); break; case ETH_P_IPV6: packet_add(pool_tap6, len, p); break; default: break; } next: p += len; n -= len; } tap4_handler(c, pool_tap4, now); tap6_handler(c, pool_tap6, now); /* We can't use EPOLLET otherwise. */ if (rem) goto redo; return 0; } /** * tap_handler_pasta() - Packet handler for tuntap file descriptor * @c: Execution context * @now: Current timestamp * * Return: -ECONNRESET on receive error, 0 otherwise */ static int tap_handler_pasta(struct ctx *c, const struct timespec *now) { ssize_t n, len; int ret; redo: n = 0; pool_flush(pool_tap4); pool_flush(pool_tap6); restart: while ((len = read(c->fd_tap, pkt_buf + n, TAP_BUF_BYTES - n)) > 0) { struct ethhdr *eh = (struct ethhdr *)(pkt_buf + n); if (len < (ssize_t)sizeof(*eh) || len > (ssize_t)ETH_MAX_MTU) { n += len; continue; } pcap(pkt_buf + n, len); if (memcmp(c->mac_guest, eh->h_source, ETH_ALEN)) { memcpy(c->mac_guest, eh->h_source, ETH_ALEN); proto_update_l2_buf(c->mac_guest, NULL, NULL); } switch (ntohs(eh->h_proto)) { case ETH_P_ARP: case ETH_P_IP: packet_add(pool_tap4, len, pkt_buf + n); break; case ETH_P_IPV6: packet_add(pool_tap6, len, pkt_buf + n); break; default: break; } if ((n += len) == TAP_BUF_BYTES) break; } if (len < 0 && errno == EINTR) goto restart; ret = errno; tap4_handler(c, pool_tap4, now); tap6_handler(c, pool_tap6, now); if (len > 0 || ret == EAGAIN) return 0; if (n == TAP_BUF_BYTES) goto redo; epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_tap, NULL); close(c->fd_tap); return -ECONNRESET; } /** * tap_sock_unix_init() - Create and bind AF_UNIX socket, listen for connection * @c: Execution context */ static void tap_sock_unix_init(struct ctx *c) { int fd = socket(AF_UNIX, SOCK_STREAM, 0); struct epoll_event ev = { 0 }; struct sockaddr_un addr = { .sun_family = AF_UNIX, }; int i; if (fd < 0) { err("UNIX socket: %s", strerror(errno)); exit(EXIT_FAILURE); } /* In passt mode, we don't know the guest's MAC until it sends * us packets. Use the broadcast address so our first packets * will reach it. */ memset(&c->mac_guest, 0xff, sizeof(c->mac_guest)); for (i = 1; i < UNIX_SOCK_MAX; i++) { char *path = addr.sun_path; int ex, ret; if (*c->sock_path) memcpy(path, c->sock_path, UNIX_PATH_MAX); else snprintf(path, UNIX_PATH_MAX - 1, UNIX_SOCK_PATH, i); ex = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0); if (ex < 0) { err("UNIX domain socket check: %s", strerror(errno)); exit(EXIT_FAILURE); } ret = connect(ex, (const struct sockaddr *)&addr, sizeof(addr)); if (!ret || (errno != ENOENT && errno != ECONNREFUSED && errno != EACCES)) { if (*c->sock_path) { err("Socket path %s already in use", path); exit(EXIT_FAILURE); } close(ex); continue; } close(ex); unlink(path); if (!bind(fd, (const struct sockaddr *)&addr, sizeof(addr)) || *c->sock_path) break; } if (i == UNIX_SOCK_MAX) { err("UNIX socket bind: %s", strerror(errno)); exit(EXIT_FAILURE); } info("UNIX domain socket bound at %s\n", addr.sun_path); listen(fd, 0); ev.data.fd = c->fd_tap_listen = fd; ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP; epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap_listen, &ev); info("You can now start qemu (>= 7.2, with commit 13c6be96618c):"); info(" kvm ... -device virtio-net-pci,netdev=s -netdev stream,id=s,server=off,addr.type=unix,addr.path=%s", addr.sun_path); info("or qrap, for earlier qemu versions:"); info(" ./qrap 5 kvm ... -net socket,fd=5 -net nic,model=virtio"); } /** * tap_sock_unix_new() - Handle new connection on listening socket * @c: Execution context */ static void tap_sock_unix_new(struct ctx *c) { struct epoll_event ev = { 0 }; int v = INT_MAX / 2; struct ucred ucred; socklen_t len; len = sizeof(ucred); /* Another client is already connected: accept and close right away. */ if (c->fd_tap != -1) { int discard = accept4(c->fd_tap_listen, NULL, NULL, SOCK_NONBLOCK); if (discard == -1) return; if (!getsockopt(discard, SOL_SOCKET, SO_PEERCRED, &ucred, &len)) info("discarding connection from PID %i", ucred.pid); close(discard); return; } c->fd_tap = accept4(c->fd_tap_listen, NULL, NULL, 0); if (!getsockopt(c->fd_tap, SOL_SOCKET, SO_PEERCRED, &ucred, &len)) info("accepted connection from PID %i", ucred.pid); if (!c->low_rmem && setsockopt(c->fd_tap, SOL_SOCKET, SO_RCVBUF, &v, sizeof(v))) trace("tap: failed to set SO_RCVBUF to %i", v); if (!c->low_wmem && setsockopt(c->fd_tap, SOL_SOCKET, SO_SNDBUF, &v, sizeof(v))) trace("tap: failed to set SO_SNDBUF to %i", v); ev.data.fd = c->fd_tap; ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP; epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev); } static int tun_ns_fd = -1; /** * tap_ns_tun() - Get tuntap fd in namespace * @c: Execution context * * Return: 0 * * #syscalls:pasta ioctl openat */ static int tap_ns_tun(void *arg) { struct ifreq ifr = { .ifr_flags = IFF_TAP | IFF_NO_PI }; int flags = O_RDWR | O_NONBLOCK | O_CLOEXEC; struct ctx *c = (struct ctx *)arg; memcpy(ifr.ifr_name, c->pasta_ifn, IFNAMSIZ); if (ns_enter(c) || (tun_ns_fd = open("/dev/net/tun", flags)) < 0 || ioctl(tun_ns_fd, TUNSETIFF, &ifr) || !(c->pasta_ifi = if_nametoindex(c->pasta_ifn))) { if (tun_ns_fd != -1) close(tun_ns_fd); tun_ns_fd = -1; } return 0; } /** * tap_sock_init_tun() - Set up tuntap file descriptor * @c: Execution context */ static void tap_sock_tun_init(struct ctx *c) { struct epoll_event ev = { 0 }; NS_CALL(tap_ns_tun, c); if (tun_ns_fd == -1) { err("Failed to open tun socket in namespace"); exit(EXIT_FAILURE); } pasta_ns_conf(c); c->fd_tap = tun_ns_fd; ev.data.fd = c->fd_tap; ev.events = EPOLLIN | EPOLLRDHUP; epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev); } /** * tap_sock_init() - Create and set up AF_UNIX socket or tuntap file descriptor * @c: Execution context */ void tap_sock_init(struct ctx *c) { size_t sz = sizeof(pkt_buf); int i; pool_tap4_storage = PACKET_INIT(pool_tap4, TAP_MSGS, pkt_buf, sz); pool_tap6_storage = PACKET_INIT(pool_tap6, TAP_MSGS, pkt_buf, sz); for (i = 0; i < TAP_SEQS; i++) { tap4_l4[i].p = PACKET_INIT(pool_l4, TAP_SEQS, pkt_buf, sz); tap6_l4[i].p = PACKET_INIT(pool_l4, TAP_SEQS, pkt_buf, sz); } if (c->fd_tap != -1) { if (c->one_off) { /* Passed as --fd */ struct epoll_event ev = { 0 }; ev.data.fd = c->fd_tap; ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP; epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev); return; } epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_tap, NULL); close(c->fd_tap); c->fd_tap = -1; } if (c->mode == MODE_PASST) { if (c->fd_tap_listen == -1) tap_sock_unix_init(c); } else { tap_sock_tun_init(c); } } /** * tap_handler() - Packet handler for AF_UNIX or tuntap file descriptor * @c: Execution context * @fd: File descriptor where event occurred * @events: epoll events * @now: Current timestamp, can be NULL on EPOLLERR */ void tap_handler(struct ctx *c, int fd, uint32_t events, const struct timespec *now) { if (fd == c->fd_tap_listen && events == EPOLLIN) { tap_sock_unix_new(c); return; } if ((c->mode == MODE_PASST && tap_handler_passt(c, now)) || (c->mode == MODE_PASTA && tap_handler_pasta(c, now))) goto reinit; if (events & (EPOLLRDHUP | EPOLLHUP | EPOLLERR)) goto reinit; return; reinit: if (c->one_off) { info("Client closed connection, exiting"); exit(EXIT_SUCCESS); } tap_sock_init(c); }