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tap.c
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tap.c
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// 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 <[email protected]>
*
*/
#include <sched.h>
#include <stdio.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdint.h>
#include <sys/epoll.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include <netinet/if_ether.h>
#include <linux/if_tun.h>
#include <linux/icmpv6.h>
#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 "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
*
* Returns: IPv4 address, network order
*/
struct in_addr tap_ip4_daddr(const struct ctx *c)
{
return c->ip4.addr_seen;
}
/**
* tap_ip6_daddr() - Normal IPv4 destination address for inbound packets
* @c: Execution context
* @src: Source address
*
* Returns: 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);
}
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) {
perror("UNIX socket");
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) {
perror("UNIX domain socket check");
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) {
perror("UNIX socket bind");
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, SOCK_CLOEXEC);
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);
}