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passt: New design and implementation with native Layer 4 sockets

Browse source 
This is a reimplementation, partially building on the earlier draft,
that uses L4 sockets (SOCK_DGRAM, SOCK_STREAM) instead of SOCK_RAW,
providing L4-L2 translation functionality without requiring any
security capability.

Conceptually, this follows the design presented at:
	https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Networking.md

The most significant novelty here comes from TCP and UDP translation
layers. In particular, the TCP state and translation logic follows
the intent of being minimalistic, without reimplementing a full TCP
stack in either direction, and synchronising as much as possible the
TCP dynamic and flows between guest and host kernel.

Another important introduction concerns addressing, port translation
and forwarding. The Layer 4 implementations now attempt to bind on
all unbound ports, in order to forward connections in a transparent
way.

While at it:
- the qemu 'tap' back-end can't be used as-is by qrap anymore,
  because of explicit checks now introduced in qemu to ensure that
  the corresponding file descriptor is actually a tap device. For
  this reason, qrap now operates on a 'socket' back-end type,
  accounting for and building the additional header reporting
  frame length

- provide a demo script that sets up namespaces, addresses and
  routes, and starts the daemon. A virtual machine started in the
  network namespace, wrapped by qrap, will now directly interface
  with passt and communicate using Layer 4 sockets provided by the
  host kernel.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-02-16 07:25:09 +01:00
parent d02e059ddc
commit 105b916361
16 changed files with 2075 additions and 638 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
Makefile
View file

@ -2,8 +2,8 @@ CFLAGS += -Wall -Wextra -pedantic
all: passt qrap
passt: passt.c passt.h arp.c arp.h dhcp.c dhcp.h ndp.c ndp.h util.c util.h
$(CC) $(CFLAGS) passt.c arp.c dhcp.c ndp.c util.c -o passt
passt: passt.c passt.h arp.c arp.h dhcp.c dhcp.h ndp.c ndp.h tap.c tap.h tcp.c tcp.h udp.c udp.h util.c util.h
$(CC) $(CFLAGS) passt.c arp.c dhcp.c ndp.c tap.c tcp.c udp.c util.c -o passt
qrap: qrap.c passt.h
$(CC) $(CFLAGS) qrap.c -o qrap

11
arp.c
View file

@ -1,9 +1,11 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* arp.c - ARP implementation
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
* License: GPLv2
*
*/
@ -23,6 +25,7 @@
#include "passt.h"
#include "dhcp.h"
#include "util.h"
#include "tap.h"
/**
* struct arpmsg - 802.2 ARP IPv4 payload
@ -39,7 +42,7 @@ struct arpmsg {
} __attribute__((__packed__));
/**
* dhcp() - Check if this is an ARP message, reply as needed
* arp() - Check if this is an ARP message, reply as needed
* @c: Execution context
* @len: Total L2 packet length
* @eh: Packet buffer, Ethernet header
@ -74,9 +77,11 @@ int arp(struct ctx *c, unsigned len, struct ethhdr *eh)
len = sizeof(*eh) + sizeof(*ah) + sizeof(*am);
memcpy(eh->h_dest, eh->h_source, ETH_ALEN);
/* HACK */
memcpy(c->mac_guest, eh->h_source, ETH_ALEN);
memcpy(eh->h_source, c->mac, ETH_ALEN);
if (send(c->fd_unix, eh, len, 0) < 0)
if (tap_send(c->fd_unix, eh, len, 0) < 0)
perror("ARP: send");
return 1;

7
dhcp.c
View file

@ -1,9 +1,11 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* dhcp.c - Minimalistic DHCP server for PASST
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
* License: GPLv2
*
*/
@ -22,6 +24,7 @@
#include "passt.h"
#include "dhcp.h"
#include "util.h"
#include "tap.h"
/**
* struct opt - DHCP option
@ -212,7 +215,7 @@ int dhcp(struct ctx *c, unsigned len, struct ethhdr *eh)
memcpy(eh->h_dest, eh->h_source, ETH_ALEN);
memcpy(eh->h_source, c->mac, ETH_ALEN);
if (send(c->fd_unix, eh, len, 0) < 0)
if (tap_send(c->fd_unix, eh, len, 0) < 0)
perror("DHCP: send");
return 1;

69
doc/demo.sh Executable file
View file

@ -0,0 +1,69 @@
#!/bin/sh -e
#
# SPDX-License-Identifier: AGPL-3.0-or-later
#
# PASST - Plug A Simple Socket Transport
#
# demo.sh - Set up namespaces, addresses and routes to show PASST functionality
#
# Copyright (c) 2020-2021 Red Hat GmbH
# Author: Stefano Brivio <sbrivio@redhat.com>
get_token() {
IFS=' '
__next=0
for __token in ${@}; do
[ ${__next} -eq 2 ] && echo "${__token}" && return
[ "${__token}" = "${1}" ] && __next=$((__next + 1))
done
unset IFS
}
ipv6_dev() { get_token "dev" $(ip -o -6 ro show default); }
ipv6_devaddr() { get_token "inet6" $(ip -o -6 ad sh dev "${1}" scope global); }
ipv6_ll_addr() { get_token "inet6" $(ip -o -6 ad sh dev "${1}" scope link); }
ipv6_mask() { echo ${1#*/}; }
ipv6_mangle() {
IFS=':'
__c=0
for __16b in ${1%%/*}; do
if [ ${__c} -lt 7 ]; then
printf "${__16b}:"
else
printf "abcd\n" && break
fi
__c=$((__c + 1))
done
unset IFS
}
ndp_setup() {
sysctl -w net.ipv6.conf.all.proxy_ndp=1
ip -6 neigh add proxy "${1}" dev "$(ipv6_dev)"
}
ip netns del passt 2>/dev/null || :
ip link del veth_passt 2>/dev/null || :
ip netns add passt
ip link add veth_passt up netns passt type veth peer name veth_passt
ip link set dev veth_passt up
ip -n passt addr add 192.0.2.2/24 dev veth_passt
ip addr add 192.0.2.1/24 dev veth_passt
ip -n passt route add default via 192.0.2.1
ipv6_addr="$(ipv6_devaddr "$(ipv6_dev)")"
ipv6_passt="$(ipv6_mangle "${ipv6_addr}")"
ndp_setup "${ipv6_passt}"
ip -n passt addr add "${ipv6_passt}/$(ipv6_mask "${ipv6_addr}")" dev veth_passt
ip addr add "${ipv6_addr}" dev veth_passt
passt_ll="$(ipv6_ll_addr "veth_passt")"
main_ll="$(get_token "link/ether" $(ip -o li sh veth_passt))"
ip -n passt neigh add "${passt_ll%%/*}" dev veth_passt lladdr "${main_ll}"
ip -n passt route add default via "${passt_ll%%/*}" dev veth_passt
ethtool -K veth_passt tx off
ip netns exec passt ethtool -K veth_passt tx off
ulimit -n 300000
ip netns exec passt ./passt

7
ndp.c
View file

@ -1,9 +1,11 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* ndp.c - NDP support for PASST
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
* License: GPLv2
*
*/
@ -23,6 +25,7 @@
#include "passt.h"
#include "util.h"
#include "tap.h"
#define RS 133
#define RA 134
@ -126,7 +129,7 @@ int ndp(struct ctx *c, unsigned len, struct ethhdr *eh)
memcpy(ehr->h_source, c->mac, ETH_ALEN);
ehr->h_proto = htons(ETH_P_IPV6);
if (send(c->fd_unix, ehr, len, 0) < 0)
if (tap_send(c->fd_unix, ehr, len, 0) < 0)
perror("NDP: send");
return 1;

697
passt.c
View file

@ -1,27 +1,16 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* passt.c - Daemon implementation
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
* License: GPLv2
*
* Grab Ethernet frames via AF_UNIX socket, build AF_INET/AF_INET6 sockets for
* each 5-tuple from ICMP, TCP, UDP packets, perform connection tracking and
* forward them with destination address NAT. Forward packets received on
* sockets back to the UNIX domain socket (typically, a tap file descriptor from
* qemu).
*
* TODO:
* - steal packets from AF_INET/AF_INET6 sockets (using eBPF/XDP, or a new
* socket option): currently, incoming packets are also handled by in-kernel
* protocol handlers, so every incoming untracked TCP packet gets a RST.
* Workaround:
* iptables -A OUTPUT -m state --state INVALID,NEW,ESTABLISHED \
* -p tcp --tcp-flags RST RST -j DROP
* ip6tables -A OUTPUT -m state --state INVALID,NEW,ESTABLISHED \
* -p tcp --tcp-flags RST RST -j DROP
* - and use XDP sockmap on top of that to improve performance
* - aging and timeout/RST bookkeeping for connection tracking entries
* Grab Ethernet frames via AF_UNIX socket, build SOCK_DGRAM/SOCK_STREAM sockets
* for each 5-tuple from TCP, UDP packets, perform connection tracking and
* forward them. Forward packets received on sockets back to the UNIX domain
* socket (typically, a socket virtio_net file descriptor from qemu).
*/
#include <stdio.h>
@ -50,15 +39,22 @@
#include <linux/ip.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <time.h>
#include "passt.h"
#include "arp.h"
#include "dhcp.h"
#include "ndp.h"
#include "util.h"
#include "tcp.h"
#include "udp.h"
#define EPOLL_EVENTS 10
#define EPOLL_TIMEOUT 100 /* ms, for protocol periodic handlers */
#define PERIODIC_HANDLER_FAST 100
#define PERIODIC_HANDLER_SLOW 1000
/**
* sock_unix() - Create and bind AF_UNIX socket, add to epoll list
*
@ -297,377 +293,43 @@ static void get_dns(struct ctx *c)
exit(EXIT_FAILURE);
}
/**
* sock_l4() - Create and bind socket for given L4, add to epoll list
* @c: Execution context
* @v: IP protocol, 4 or 6
* @proto: Protocol number, network order
* @port: L4 port, network order
*
* Return: newly created socket, -1 on error
*/
static int sock_l4(struct ctx *c, int v, uint16_t proto, uint16_t port)
{
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = port,
.sin_addr = { .s_addr = c->addr4 },
};
struct sockaddr_in6 addr6 = {
.sin6_family = AF_INET6,
.sin6_port = port,
.sin6_addr = c->addr6,
};
struct epoll_event ev = { 0 };
const struct sockaddr *sa;
int fd, sl;
fd = socket(v == 4 ? AF_INET : AF_INET6, SOCK_RAW, proto);
if (fd < 0) {
perror("L4 socket");
return -1;
}
if (v == 4) {
sa = (const struct sockaddr *)&addr4;
sl = sizeof(addr4);
} else {
sa = (const struct sockaddr *)&addr6;
sl = sizeof(addr6);
}
if (bind(fd, sa, sl) < 0) {
perror("L4 bind");
close(fd);
return -1;
}
ev.events = EPOLLIN;
ev.data.fd = fd;
if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, fd, &ev) == -1) {
perror("L4 epoll_ctl");
return -1;
}
return fd;
}
/**
* lookup4() - Look up entry from tap-sourced IPv4 packet, create if missing
* @c: Execution context
* @eh: Packet buffer, Ethernet header
*
* Return: -1 for unsupported or too many sockets, matching socket otherwise
*/
static int lookup4(struct ctx *c, const struct ethhdr *eh)
{
struct iphdr *iph = (struct iphdr *)(eh + 1);
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
char buf_s[BUFSIZ], buf_d[BUFSIZ];
struct ct4 *ct = c->map4;
int i, one_icmp_fd = 0;
if (iph->protocol != IPPROTO_ICMP && iph->protocol != IPPROTO_TCP &&
iph->protocol != IPPROTO_UDP)
return -1;
for (i = 0; i < CT_SIZE; i++) {
if (ct[i].p == iph->protocol && ct[i].sa == iph->saddr &&
((ct[i].p == IPPROTO_ICMP && ct[i].da == iph->daddr)
|| ct[i].sp == th->source) &&
!memcmp(ct[i].hd, eh->h_dest, ETH_ALEN) &&
!memcmp(ct[i].hs, eh->h_source, ETH_ALEN)) {
if (iph->protocol != IPPROTO_ICMP) {
ct[i].da = iph->daddr;
ct[i].dp = th->dest;
}
return ct[i].fd;
}
}
for (i = 0; i < CT_SIZE && ct[i].p; i++) {
if (iph->protocol == IPPROTO_ICMP && ct[i].p == IPPROTO_ICMP)
one_icmp_fd = ct[i].fd;
}
if (i == CT_SIZE) {
fprintf(stderr, "\nToo many sockets, aborting ");
} else {
if (iph->protocol == IPPROTO_ICMP) {
if (one_icmp_fd)
ct[i].fd = one_icmp_fd;
else
ct[i].fd = sock_l4(c, 4, iph->protocol, 0);
} else {
ct[i].fd = sock_l4(c, 4, iph->protocol, th->source);
}
fprintf(stderr, "\n(socket %i) New ", ct[i].fd);
ct[i].p = iph->protocol;
ct[i].sa = iph->saddr;
ct[i].da = iph->daddr;
if (iph->protocol != IPPROTO_ICMP) {
ct[i].sp = th->source;
ct[i].dp = th->dest;
}
memcpy(&ct[i].hd, eh->h_dest, ETH_ALEN);
memcpy(&ct[i].hs, eh->h_source, ETH_ALEN);
}
if (iph->protocol == IPPROTO_ICMP) {
fprintf(stderr, "icmp connection\n\tfrom %s to %s\n\n",
inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)));
} else {
fprintf(stderr, "%s connection\n\tfrom %s:%i to %s:%i\n\n",
getprotobynumber(iph->protocol)->p_name,
inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
ntohs(th->source),
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)),
ntohs(th->dest));
}
return (i == CT_SIZE) ? -1 : ct[i].fd;
}
/**
* lookup6() - Look up entry from tap-sourced IPv6 packet, create if missing
* @c: Execution context
* @eh: Packet buffer, Ethernet header
*
* Return: -1 for unsupported or too many sockets, matching socket otherwise
*/
static int lookup6(struct ctx *c, const struct ethhdr *eh)
{
struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
char buf_s[BUFSIZ], buf_d[BUFSIZ];
struct ct6 *ct = c->map6;
int i, one_icmp_fd = 0;
struct tcphdr *th;
uint8_t proto;
th = (struct tcphdr *)ipv6_l4hdr(ip6h, &proto);
if (!th)
return -1;
if (proto != IPPROTO_ICMPV6 && proto != IPPROTO_TCP &&
proto != IPPROTO_UDP)
return -1;
for (i = 0; i < CT_SIZE; i++) {
if (ct[i].p != proto)
continue;
if (memcmp(ct[i].hd, eh->h_dest, ETH_ALEN) ||
memcmp(ct[i].hs, eh->h_source, ETH_ALEN) ||
memcmp(&ct[i].sa, &ip6h->saddr, sizeof(ct[i].sa)))
continue;
if (ct[i].p != IPPROTO_ICMPV6 &&
ct[i].sp != th->source)
continue;
if (ct[i].p == IPPROTO_ICMPV6 &&
memcmp(&ct[i].da, &ip6h->daddr, sizeof(ct[i].da)))
continue;
if (ct[i].p != IPPROTO_ICMPV6) {
memcpy(&ct[i].da, &ip6h->daddr, sizeof(ct[i].da));
ct[i].dp = th->dest;
}
return ct[i].fd;
}
for (i = 0; i < CT_SIZE && ct[i].p; i++) {
if (proto == IPPROTO_ICMPV6 && ct[i].p == IPPROTO_ICMPV6)
one_icmp_fd = ct[i].fd;
}
if (i == CT_SIZE) {
fprintf(stderr, "\nToo many sockets, aborting ");
} else {
if (proto == IPPROTO_ICMPV6) {
if (one_icmp_fd)
ct[i].fd = one_icmp_fd;
else
ct[i].fd = sock_l4(c, 6, proto, 0);
} else {
ct[i].fd = sock_l4(c, 6, proto, th->source);
}
fprintf(stderr, "\n(socket %i) New ", ct[i].fd);
ct[i].p = proto;
memcpy(&ct[i].sa, &ip6h->saddr, sizeof(ct[i].sa));
memcpy(&ct[i].da, &ip6h->daddr, sizeof(ct[i].da));
if (ct[i].p != IPPROTO_ICMPV6) {
ct[i].sp = th->source;
ct[i].dp = th->dest;
}
memcpy(&ct[i].hd, eh->h_dest, ETH_ALEN);
memcpy(&ct[i].hs, eh->h_source, ETH_ALEN);
}
if (proto == IPPROTO_ICMPV6) {
fprintf(stderr, "icmpv6 connection\n\tfrom %s\n"
"\tto %s\n\n",
inet_ntop(AF_INET6, &ct[i].sa, buf_s, sizeof(buf_s)),
inet_ntop(AF_INET6, &ct[i].da, buf_d, sizeof(buf_d)));
} else {
fprintf(stderr, "%s connection\n\tfrom [%s]:%i\n"
"\tto [%s]:%i\n\n",
getprotobynumber(proto)->p_name,
inet_ntop(AF_INET6, &ct[i].sa, buf_s, sizeof(buf_s)),
ntohs(th->source),
inet_ntop(AF_INET6, &ct[i].da, buf_d, sizeof(buf_d)),
ntohs(th->dest));
}
return (i == CT_SIZE) ? -1 : ct[i].fd;
}
/**
* lookup_r4() - Reverse look up connection tracking entry for IPv4 packet
* @ct: Connection tracking table
* @fd: File descriptor that received the packet
* @iph: Packet buffer, IP header
*
* Return: matching entry if any, NULL otherwise
*/
struct ct4 *lookup_r4(struct ct4 *ct, int fd, struct iphdr *iph)
{
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
int i;
for (i = 0; i < CT_SIZE; i++) {
if (ct[i].fd == fd &&
iph->protocol == ct[i].p &&
iph->saddr == ct[i].da &&
(iph->protocol == IPPROTO_ICMP ||
(th->source == ct[i].dp && th->dest == ct[i].sp)))
return &ct[i];
}
return NULL;
}
/**
* lookup_r6() - Reverse look up connection tracking entry for IPv6 packet
* @ct: Connection tracking table
* @fd: File descriptor that received the packet
*
* Return: matching entry if any, NULL otherwise
*/
struct ct6 *lookup_r6(struct ct6 *ct, int fd, struct tcphdr *th)
{
int i;
for (i = 0; i < CT_SIZE; i++) {
if (ct[i].fd != fd)
continue;
if (ct[i].p == IPPROTO_ICMPV6 ||
(ct[i].dp == th->source && ct[i].sp == th->dest))
return &ct[i];
}
return NULL;
}
/**
* nat4_in() - Perform incoming IPv4 address translation
* @addr: Original destination address to be used
* @iph: IP header
*/
static void nat_in(unsigned long addr, struct iphdr *iph)
{
iph->daddr = addr;
}
/**
* csum_ipv4() - Calculate TCP checksum for IPv4 and set in place
* @iph: Packet buffer, IP header
*/
static void csum_tcp4(struct iphdr *iph)
{
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
uint16_t tlen = ntohs(iph->tot_len) - iph->ihl * 4, *p = (uint16_t *)th;
uint32_t sum = 0;
sum += (iph->saddr >> 16) & 0xffff;
sum += iph->saddr & 0xffff;
sum += (iph->daddr >> 16) & 0xffff;
sum += iph->daddr & 0xffff;
sum += htons(IPPROTO_TCP);
sum += htons(tlen);
th->check = 0;
while (tlen > 1) {
sum += *p++;
tlen -= 2;
}
if (tlen > 0) {
sum += *p & htons(0xff00);
}
th->check = (uint16_t)~csum_fold(sum);
}
/**
* tap4_handler() - IPv4 packet handler for tap file descriptor
* @c: Execution context
* @len: Total L2 packet length
* @in: Packet buffer, L2 headers
*/
static void tap4_handler(struct ctx *c, int len, char *in)
static void tap4_handler(struct ctx *c, char *in, size_t len)
{
struct ethhdr *eh = (struct ethhdr *)in;
struct iphdr *iph = (struct iphdr *)(eh + 1);
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
struct udphdr *uh = (struct udphdr *)th;
struct sockaddr_in addr = {
.sin_family = AF_INET,
.sin_port = th->dest,
.sin_addr = { .s_addr = iph->daddr },
};
char *l4h = (char *)iph + iph->ihl * 4;
char buf_s[BUFSIZ], buf_d[BUFSIZ];
int fd;
if (arp(c, len, eh) || dhcp(c, len, eh))
return;
fd = lookup4(c, eh);
if (fd == -1)
return;
if (iph->protocol == IPPROTO_ICMP) {
fprintf(stderr, "icmp from tap: %s -> %s (socket %i)\n",
fprintf(stderr, "icmp from tap: %s -> %s\n",
inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)),
fd);
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)));
} else {
fprintf(stderr, "%s from tap: %s:%i -> %s:%i (socket %i)\n",
struct tcphdr *th = (struct tcphdr *)l4h;
fprintf(stderr, "%s from tap: %s:%i -> %s:%i\n",
getprotobynumber(iph->protocol)->p_name,
inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
ntohs(th->source),
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)),
ntohs(th->dest),
fd);
ntohs(th->dest));
}
len -= (intptr_t)l4h - (intptr_t)eh;
if (iph->protocol == IPPROTO_TCP)
csum_tcp4(iph);
tcp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
else if (iph->protocol == IPPROTO_UDP)
uh->check = 0;
else if (iph->protocol != IPPROTO_ICMP)
return;
if (sendto(fd, (void *)th, len - sizeof(*eh) - iph->ihl * 4, 0,
(struct sockaddr *)&addr, sizeof(addr)) < 0)
perror("sendto");
udp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
}
/**
@ -676,228 +338,122 @@ static void tap4_handler(struct ctx *c, int len, char *in)
* @len: Total L2 packet length
* @in: Packet buffer, L2 headers
*/
static void tap6_handler(struct ctx *c, int len, char *in)
static void tap6_handler(struct ctx *c, char *in, size_t len)
{
struct ethhdr *eh = (struct ethhdr *)in;
struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
struct tcphdr *th;
struct udphdr *uh;
struct icmp6hdr *ih;
struct sockaddr_in6 addr = {
.sin6_family = AF_INET6,
.sin6_addr = ip6h->daddr,
};
char buf_s[BUFSIZ], buf_d[BUFSIZ];
uint8_t proto;
int fd;
char *l4h;
if (ndp(c, len, eh))
return;
fd = lookup6(c, eh);
if (fd == -1)
return;
th = (struct tcphdr *)ipv6_l4hdr(ip6h, &proto);
uh = (struct udphdr *)th;
ih = (struct icmp6hdr *)th;
if (proto == IPPROTO_ICMPV6) {
fprintf(stderr, "icmpv6 from tap: %s ->\n\t%s (socket %i)\n",
inet_ntop(AF_INET6, &ip6h->saddr, buf_s, sizeof(buf_s)),
inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d)),
fd);
} else {
fprintf(stderr, "%s from tap: [%s]:%i\n"
"\t-> [%s]:%i (socket %i)\n",
getprotobynumber(proto)->p_name,
inet_ntop(AF_INET6, &ip6h->saddr, buf_s, sizeof(buf_s)),
ntohs(th->source),
inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d)),
ntohs(th->dest),
fd);
}
if (proto != IPPROTO_TCP && proto != IPPROTO_UDP &&
proto != IPPROTO_ICMPV6)
return;
l4h = ipv6_l4hdr(ip6h, &proto);
/* TODO: Assign MAC address to guest so that, together with prefix
* assigned via NDP, address matches the one on the host. Then drop
* address change and checksum recomputation.
*/
c->addr6_guest = ip6h->saddr;
ip6h->saddr = c->addr6;
ip6h->hop_limit = proto;
ip6h->version = 0;
ip6h->nexthdr = 0;
memset(ip6h->flow_lbl, 0, 3);
if (proto == IPPROTO_TCP) {
th->check = 0;
th->check = csum_ip4(ip6h,
len - ((intptr_t)th - (intptr_t)eh) +
sizeof(*ip6h));
} else if (proto == IPPROTO_UDP) {
uh->check = 0;
uh->check = csum_ip4(ip6h,
len - ((intptr_t)uh - (intptr_t)eh) +
sizeof(*ip6h));
} else if (proto == IPPROTO_ICMPV6) {
ih->icmp6_cksum = 0;
ih->icmp6_cksum = csum_ip4(ip6h,
len - ((intptr_t)ih - (intptr_t)eh) +
sizeof(*ip6h));
}
struct tcphdr *th = (struct tcphdr *)(ip6h + 1);
ip6h->version = 6;
ip6h->nexthdr = proto;
ip6h->hop_limit = 255;
if (sendto(fd, (void *)th, len - ((intptr_t)th - (intptr_t)eh), 0,
(struct sockaddr *)&addr, sizeof(addr)) < 0)
perror("sendto");
}
static void tap_handler(struct ctx *c, int len, char *in)
{
struct ethhdr *eh = (struct ethhdr *)in;
if (eh->h_proto == ntohs(ETH_P_IP) || eh->h_proto == ntohs(ETH_P_ARP))
tap4_handler(c, len, in);
else if (eh->h_proto == ntohs(ETH_P_IPV6))
tap6_handler(c, len, in);
}
/**
* ext4_handler() - IPv4 packet handler for external routable interface
* @c: Execution context
* @fd: File descriptor that received the packet
* @len: Total L3 packet length
* @in: Packet buffer, L3 headers
*/
static void ext4_handler(struct ctx *c, int fd, int len, char *in)
{
struct iphdr *iph = (struct iphdr *)in;
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
struct udphdr *uh = (struct udphdr *)th;
char buf_s[BUFSIZ], buf_d[BUFSIZ], buf[ETH_MAX_MTU];
struct ethhdr *eh = (struct ethhdr *)buf;
struct ct4 *entry;
entry = lookup_r4(c->map4, fd, iph);
if (!entry)
return;
nat_in(entry->sa, iph);
iph->check = 0;
iph->check = csum_ip4(iph, iph->ihl * 4);
if (iph->protocol == IPPROTO_TCP)
csum_tcp4(iph);
else if (iph->protocol == IPPROTO_UDP)
uh->check = 0;
memcpy(eh->h_dest, entry->hs, ETH_ALEN);
memcpy(eh->h_source, entry->hd, ETH_ALEN);
eh->h_proto = ntohs(ETH_P_IP);
memcpy(eh + 1, in, len);
if (iph->protocol == IPPROTO_ICMP) {
fprintf(stderr, "icmp (socket %i) to tap: %s -> %s\n",
entry->fd,
inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)));
} else {
fprintf(stderr, "%s (socket %i) to tap: %s:%i -> %s:%i\n",
getprotobynumber(iph->protocol)->p_name,
entry->fd,
inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
ntohs(th->source),
inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)),
ntohs(th->dest));
}
if (send(c->fd_unix, buf, len + sizeof(*eh), 0) < 0)
perror("send");
}
/**
* ext6_handler() - IPv6 packet handler for external routable interface
* @c: Execution context
* @fd: File descriptor that received the packet
* @len: Total L4 packet length
* @in: Packet buffer, L4 headers
*/
static int ext6_handler(struct ctx *c, int fd, int len, char *in)
{
struct tcphdr *th = (struct tcphdr *)in;
struct udphdr *uh;
struct icmp6hdr *ih;
char buf_s[BUFSIZ], buf_d[BUFSIZ], buf[ETH_MAX_MTU] = { 0 };
struct ethhdr *eh = (struct ethhdr *)buf;
struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
struct ct6 *entry;
entry = lookup_r6(c->map6, fd, th);
if (!entry)
return 0;
ip6h->daddr = entry->sa;
ip6h->saddr = entry->da;
memcpy(ip6h + 1, in, len);
ip6h->payload_len = htons(len);
th = (struct tcphdr *)(ip6h + 1);
uh = (struct udphdr *)th;
ih = (struct icmp6hdr *)th;
ip6h->hop_limit = entry->p;
if (entry->p == IPPROTO_TCP) {
th->check = 0;
th->check = csum_ip4(ip6h, len + sizeof(*ip6h));
} else if (entry->p == IPPROTO_UDP) {
} else if (proto == IPPROTO_UDP) {
struct udphdr *uh = (struct udphdr *)(ip6h + 1);
uh->check = 0;
uh->check = csum_ip4(ip6h, len + sizeof(*ip6h));
} else if (entry->p == IPPROTO_ICMPV6) {
} else if (proto == IPPROTO_ICMPV6) {
struct icmp6hdr *ih = (struct icmp6hdr *)(ip6h + 1);
ih->icmp6_cksum = 0;
ih->icmp6_cksum = csum_ip4(ip6h, len + sizeof(*ip6h));
}
ip6h->version = 6;
ip6h->nexthdr = entry->p;
ip6h->hop_limit = 255;
memcpy(eh->h_dest, entry->hs, ETH_ALEN);
memcpy(eh->h_source, entry->hd, ETH_ALEN);
eh->h_proto = ntohs(ETH_P_IPV6);
if (entry->p == IPPROTO_ICMPV6) {
fprintf(stderr, "icmpv6 (socket %i) to tap: %s\n\t-> %s\n",
entry->fd,
if (proto == IPPROTO_ICMPV6) {
fprintf(stderr, "icmpv6 from tap: %s ->\n\t%s\n",
inet_ntop(AF_INET6, &ip6h->saddr, buf_s, sizeof(buf_s)),
inet_ntop(AF_INET6, &ip6h->daddr, buf_d,
sizeof(buf_d)));
inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d))
);
} else {
fprintf(stderr, "%s (socket %i) to tap: [%s]:%i\n"
struct tcphdr *th = (struct tcphdr *)l4h;
fprintf(stderr, "%s from tap: [%s]:%i\n"
"\t-> [%s]:%i\n",
getprotobynumber(entry->p)->p_name,
entry->fd,
getprotobynumber(proto)->p_name,
inet_ntop(AF_INET6, &ip6h->saddr, buf_s, sizeof(buf_s)),
ntohs(th->source),
inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d)),
ntohs(th->dest));
}
if (send(c->fd_unix, buf, len + sizeof(*ip6h) + sizeof(*eh), 0) < 0)
perror("send");
len -= (intptr_t)l4h - (intptr_t)eh;
return 1;
if (proto == IPPROTO_TCP)
tcp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len);
else if (proto == IPPROTO_UDP)
udp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len);
}
static void ext_handler(struct ctx *c, int fd, int len, char *in)
/**
* tap_handler() - IPv4/IPv6/ARP packet handler for tap file descriptor
* @c: Execution context
* @len: Total L2 packet length
* @in: Packet buffer, L2 headers
*/
static void tap_handler(struct ctx *c, char *in, size_t len)
{
if (!ext6_handler(c, fd, len, in))
ext4_handler(c, fd, len, in);
struct ethhdr *eh = (struct ethhdr *)in;
if (eh->h_proto == ntohs(ETH_P_IP) || eh->h_proto == ntohs(ETH_P_ARP))
tap4_handler(c, in, len);
else if (eh->h_proto == ntohs(ETH_P_IPV6))
tap6_handler(c, in, len);
}
/**
* sock_handler() - Event handler for L4 sockets
* @c: Execution context
* @fd: File descriptor associated to event
* @events epoll events
*/
static void sock_handler(struct ctx *c, int fd, uint32_t events)
{
socklen_t sl;
int so;
sl = sizeof(so);
if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &so, &sl) ||
so == SOCK_STREAM)
tcp_sock_handler(c, fd, events);
else if (so == SOCK_DGRAM)
udp_sock_handler(c, fd, events);
}
/**
* periodic_handler() - Run periodic tasks for L4 protocol handlers
* @c: Execution context
* @last: Timestamp of last run, updated on return
*/
static void periodic_handler(struct ctx *c, struct timespec *last)
{
struct timespec tmp;
int elapsed_ms;
clock_gettime(CLOCK_MONOTONIC, &tmp);
elapsed_ms = timespec_diff_ms(&tmp, last);
if (elapsed_ms >= PERIODIC_HANDLER_FAST)
tcp_periodic_fast(c);
if (elapsed_ms >= PERIODIC_HANDLER_SLOW)
tcp_periodic_slow(c);
*last = tmp;
}
/**
@ -924,6 +480,7 @@ int main(int argc, char **argv)
char buf4[4][sizeof("255.255.255.255")];
struct epoll_event events[EPOLL_EVENTS];
struct epoll_event ev = { 0 };
struct timespec last_time;
char buf[ETH_MAX_MTU];
struct ctx c = { 0 };
int nfds, i, len;
@ -958,36 +515,49 @@ int main(int argc, char **argv)
}
fprintf(stderr, "\n");
if (clock_gettime(CLOCK_MONOTONIC, &last_time)) {
perror("clock_gettime");
exit(EXIT_FAILURE);
}
c.epollfd = epoll_create1(0);
if (c.epollfd == -1) {
perror("epoll_create1");
exit(EXIT_FAILURE);
}
if (tcp_sock_init(&c) || udp_sock_init(&c))
exit(EXIT_FAILURE);
fd_unix = sock_unix();
listen:
listen(fd_unix, 1);
fprintf(stderr,
"You can now start qrap:\n\t"
"./qrap 42 kvm ... -net tap,fd=42 -net nic,model=virtio\n\n");
"./qrap 5 kvm ... -net socket,fd=5 -net nic,model=virtio\n\n");
c.fd_unix = accept(fd_unix, NULL, NULL);
ev.events = EPOLLIN;
ev.events = EPOLLIN | EPOLLRDHUP | EPOLLERR | EPOLLHUP;
ev.data.fd = c.fd_unix;
epoll_ctl(c.epollfd, EPOLL_CTL_ADD, c.fd_unix, &ev);
clock_gettime(CLOCK_MONOTONIC, &last_time);
loop:
nfds = epoll_wait(c.epollfd, events, EPOLL_EVENTS, -1);
nfds = epoll_wait(c.epollfd, events, EPOLL_EVENTS, EPOLL_TIMEOUT);
if (nfds == -1 && errno != EINTR) {
perror("epoll_wait");
exit(EXIT_FAILURE);
}
for (i = 0; i < nfds; i++) {
len = recv(events[i].data.fd, buf, sizeof(buf), MSG_DONTWAIT);
if (events[i].data.fd == c.fd_unix) {
len = recv(events[i].data.fd, buf, sizeof(buf),
MSG_DONTWAIT);
if (events[i].data.fd == c.fd_unix && len <= 0) {
epoll_ctl(c.epollfd, EPOLL_CTL_DEL, c.fd_unix, &ev);
if (len <= 0) {
epoll_ctl(c.epollfd, EPOLL_CTL_DEL, c.fd_unix,
&ev);
close(c.fd_unix);
goto listen;
}
@ -1001,11 +571,14 @@ loop:
goto out;
}
if (events[i].data.fd == c.fd_unix)
tap_handler(&c, len, buf);
else
ext_handler(&c, events[i].data.fd, len, buf);
tap_handler(&c, buf + 4, ntohl(*(uint32_t *)buf));
} else {
sock_handler(&c, events[i].data.fd, events[i].events);
}
}
periodic_handler(&c, &last_time);
clock_gettime(CLOCK_MONOTONIC, &last_time);
goto loop;

52
passt.h
View file

@ -1,56 +1,12 @@
#define CT_SIZE 4096
#define UNIX_SOCK_PATH "/tmp/passt.socket"
/**
* struct ct4 - IPv4 connection tracking entry
* @p: IANA protocol number
* @sa: Source address (as seen from tap interface)
* @da: Destination address
* @sp: Source port, network order
* @dp: Destination port, network order
* @hd: Destination MAC address
* @hs: Source MAC address
* @fd: File descriptor for corresponding AF_INET socket
*/
struct ct4 {
uint8_t p;
uint32_t sa;
uint32_t da;
uint16_t sp;
uint16_t dp;
unsigned char hd[ETH_ALEN];
unsigned char hs[ETH_ALEN];
int fd;
};
/**
* struct ct6 - IPv6 connection tracking entry
* @p: IANA protocol number
* @sa: Source address (as seen from tap interface)
* @da: Destination address
* @sp: Source port, network order
* @dp: Destination port, network order
* @hd: Destination MAC address
* @hs: Source MAC address
* @fd: File descriptor for corresponding AF_INET6 socket
*/
struct ct6 {
uint8_t p;
struct in6_addr sa;
struct in6_addr da;
uint16_t sp;
uint16_t dp;
unsigned char hd[ETH_ALEN];
unsigned char hs[ETH_ALEN];
int fd;
};
/**
* struct ctx - Execution context
* @epollfd: file descriptor for epoll instance
* @fd_unix: AF_UNIX socket for tap file descriptor
* @map4: Connection tracking table
* @v4: Enable IPv4 transport
* @mac: Host MAC address
* @mac_guest: Guest MAC address
* @addr4: IPv4 address for external, routable interface
* @mask4: IPv4 netmask, network order
* @gw4: Default IPv4 gateway, network order
@ -64,9 +20,8 @@ struct ct6 {
struct ctx {
int epollfd;
int fd_unix;
struct ct4 map4[CT_SIZE];
struct ct6 map6[CT_SIZE];
unsigned char mac[ETH_ALEN];
unsigned char mac_guest[ETH_ALEN];
int v4;
unsigned long addr4;
@ -76,6 +31,7 @@ struct ctx {
int v6;
struct in6_addr addr6;
struct in6_addr addr6_guest;
struct in6_addr gw6;
struct in6_addr dns6;

6
qrap.c
View file

@ -1,9 +1,11 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* qrap.c - qemu wrapper connecting UNIX domain socket to tap file descriptor
* qrap.c - qemu wrapper connecting UNIX domain socket to socket file descriptor
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
* License: GPLv2
*
* TODO: Implement this functionality directly in qemu: we have TCP and UDP
* socket back-ends already.

136
tap.c Normal file
View file

@ -0,0 +1,136 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* tap.c - Functions to communicate with guest-facing tap interface
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
#include <stdio.h>
#include <limits.h>
#include <string.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdint.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <linux/icmpv6.h>
#include "passt.h"
#include "util.h"
/**
* tap_send() - Send frame and qemu socket header with indication of length
* @fd: tap file descriptor
* @len: Total L2 packet length
* @flags: Flags for send(), if any
*
* Return: return code from send()
*/
int tap_send(int fd, void *data, size_t len, int flags)
{
uint32_t vnet_len = htonl(len);
send(fd, &vnet_len, 4, 0);
return send(fd, data, len, flags);
}
/**
* tap_ip_send() - Send IP packet, with L2 headers, calculating L3/L4 checksums
* @c: Execution context
* @src: IPv6 source address, IPv4-mapped for IPv4 sources
* @proto: L4 protocol number
* @in: Payload
* @len: L4 payload length
*/
void tap_ip_send(struct ctx *c, struct in6_addr *src, uint8_t proto,
char *in, size_t len)
{
char pkt[USHRT_MAX];
struct ethhdr *eh;
eh = (struct ethhdr *)pkt;
/* TODO: ARP table lookup */
memcpy(eh->h_dest, c->mac_guest, ETH_ALEN);
memcpy(eh->h_source, c->mac, ETH_ALEN);
if (IN6_IS_ADDR_V4MAPPED(src)) {
struct iphdr *iph = (struct iphdr *)(eh + 1);
char *data = (char *)(iph + 1);
eh->h_proto = ntohs(ETH_P_IP);
iph->version = 4;
iph->ihl = 5;
iph->tos = 0;
iph->tot_len = htons(len + 20);
iph->id = 0;
iph->frag_off = 0;
iph->ttl = 255;
iph->protocol = proto;
iph->daddr = c->addr4;
memcpy(&iph->saddr, &src->s6_addr[12], 4);
iph->check = 0;
iph->check = csum_ip4(iph, iph->ihl * 4);
memcpy(data, in, len);
if (iph->protocol == IPPROTO_TCP) {
csum_tcp4(iph);
} else if (iph->protocol == IPPROTO_UDP) {
struct udphdr *uh = (struct udphdr *)(iph + 1);
uh->check = 0;
}
tap_send(c->fd_unix, pkt, len + sizeof(*iph) + sizeof(*eh), 0);
} else {
struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
char *data = (char *)(ip6h + 1);
eh->h_proto = ntohs(ETH_P_IPV6);
memset(ip6h->flow_lbl, 0, 3);
ip6h->payload_len = htons(len);
ip6h->priority = 0;
ip6h->saddr = *src;
ip6h->daddr = c->addr6_guest;
memcpy(data, in, len);
ip6h->hop_limit = proto;
ip6h->version = 0;
ip6h->nexthdr = 0;
if (proto == IPPROTO_TCP) {
struct tcphdr *th = (struct tcphdr *)(ip6h + 1);
th->check = 0;
th->check = csum_ip4(ip6h, len + sizeof(*ip6h));
} else if (proto == IPPROTO_UDP) {
struct udphdr *uh = (struct udphdr *)(ip6h + 1);
uh->check = 0;
uh->check = csum_ip4(ip6h, len + sizeof(*ip6h));
} else if (proto == IPPROTO_ICMPV6) {
struct icmp6hdr *ih = (struct icmp6hdr *)(ip6h + 1);
ih->icmp6_cksum = 0;
ih->icmp6_cksum = csum_ip4(ip6h, len + sizeof(*ip6h));
}
ip6h->version = 6;
ip6h->nexthdr = proto;
ip6h->hop_limit = 255;
tap_send(c->fd_unix, pkt, len + sizeof(*ip6h) + sizeof(*eh), 0);
}
}

3
tap.h Normal file
View file

@ -0,0 +1,3 @@
void tap_ip_send(struct ctx *c, struct in6_addr *src, uint8_t proto,
char *in, size_t len);
int tap_send(int fd, void *data, size_t len, int flags);

1367
tcp.c Normal file
View file

File diff suppressed because it is too large Load diff

5
tcp.h Normal file
View file

@ -0,0 +1,5 @@
void tcp_sock_handler(struct ctx *c, int s, uint32_t events);
void tcp_tap_handler(struct ctx *c, int af, void *addr, char *in, size_t len);
int tcp_sock_init(struct ctx *c);
void tcp_periodic_fast(struct ctx *c);
void tcp_periodic_slow(struct ctx *c);

174
udp.c Normal file
View file

@ -0,0 +1,174 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* udp.c - UDP L2-L4 translation routines
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
/**
* DOC: Theory of Operation
*
*
* For UDP, no state machine or any particular tracking is required. Try to
* create and bind sets of 2^16 sockets, one for IPv4 and one for IPv6. Binding
* will fail on ports that are already bound, or low ports depending on
* capabilities.
*
* Packets are forwarded back and forth, by prepending and stripping UDP headers
* in the obvious way, with no port translation.
*
*/
#include <stdio.h>
#include <errno.h>
#include <limits.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/udp.h>
#include <time.h>
#include "passt.h"
#include "tap.h"
#include "util.h"
static int udp4_sock_port[USHRT_MAX];
static int udp6_sock_port[USHRT_MAX];
/**
* udp_sock_handler() - Handle new data from socket
* @c: Execution context
* @s: File descriptor number for socket
* @events: epoll events bitmap
*/
void udp_sock_handler(struct ctx *c, int s, uint32_t events)
{
struct in6_addr a6 = { .s6_addr = { 0, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0xff, 0xff,
0, 0, 0, 0 } };
struct sockaddr_storage sr, sl;
socklen_t slen = sizeof(sr);
char buf[USHRT_MAX];
struct udphdr *uh;
int n;
(void)events;
n = recvfrom(s, buf + sizeof(*uh), sizeof(buf) - sizeof(*uh),
MSG_DONTWAIT, (struct sockaddr *)&sr, &slen);
if (n < 0)
return;
uh = (struct udphdr *)buf;
if (getsockname(s, (struct sockaddr *)&sl, &slen))
return;
if (sl.ss_family == AF_INET) {
struct sockaddr_in *sr4 = (struct sockaddr_in *)&sr;
struct sockaddr_in *sl4 = (struct sockaddr_in *)&sl;
memcpy(&a6.s6_addr[12], &sr4->sin_addr, sizeof(sr4->sin_addr));
uh->source = sr4->sin_port;
uh->dest = sl4->sin_port;
uh->len = htons(n + sizeof(*uh));
tap_ip_send(c, &a6, IPPROTO_UDP, buf, n + sizeof(*uh));
} else if (sl.ss_family == AF_INET6) {
struct sockaddr_in6 *sr6 = (struct sockaddr_in6 *)&sr;
struct sockaddr_in6 *sl6 = (struct sockaddr_in6 *)&sl;
uh->source = sr6->sin6_port;
uh->dest = sl6->sin6_port;
uh->len = htons(n + sizeof(*uh));
tap_ip_send(c, &sr6->sin6_addr, IPPROTO_UDP,
buf, n + sizeof(*uh));
}
}
/**
* tcp_tap_handler() - Handle packets from tap
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @in: Input buffer
* @len: Length, including UDP header
*/
void udp_tap_handler(struct ctx *c, int af, void *addr, char *in, size_t len)
{
struct udphdr *uh = (struct udphdr *)in;
int s;
(void)c;
if (af == AF_INET) {
struct sockaddr_in sa = {
.sin_family = AF_INET,
.sin_port = uh->dest,
};
if (!(s = udp4_sock_port[ntohs(uh->source)]))
return;
fprintf(stderr, "udp from tap: using socket %i\n", s);
sa.sin_addr = *(struct in_addr *)addr;
sendto(s, in + sizeof(*uh), len - sizeof(*uh), MSG_DONTWAIT,
(struct sockaddr *)&sa, sizeof(sa));
} else if (af == AF_INET6) {
struct sockaddr_in6 sa = {
.sin6_family = AF_INET6,
.sin6_port = uh->dest,
.sin6_addr = *(struct in6_addr *)addr,
};
if (!(s = udp6_sock_port[ntohs(uh->source)]))
return;
fprintf(stderr, "udp from tap: using socket %i\n", s);
sendto(s, in + sizeof(*uh), len - sizeof(*uh), MSG_DONTWAIT,
(struct sockaddr *)&sa, sizeof(sa));
}
}
/**
* udp_sock_init() - Create and bind listening sockets for inbound connections
* @c: Execution context
*
* Return: 0 on success, -1 on failure
*/
int udp_sock_init(struct ctx *c)
{
in_port_t port;
int s;
for (port = 0; port < USHRT_MAX; port++) {
if (c->v4 &&
(s = sock_l4_add(c, 4, IPPROTO_UDP, htons(port))) < 0)
return -1;
udp4_sock_port[port] = s;
if (c->v6 &&
(s = sock_l4_add(c, 6, IPPROTO_UDP, htons(port))) < 0)
return -1;
udp6_sock_port[port] = s;
}
return 0;
}

3
udp.h Normal file
View file

@ -0,0 +1,3 @@
void udp_sock_handler(struct ctx *c, int s, uint32_t events);
void udp_tap_handler(struct ctx *c, int af, void *addr, char *in, size_t len);
int udp_sock_init(struct ctx *c);

141
util.c
View file

@ -1,17 +1,28 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* util.c - Convenience helpers
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
* License: GPLv2
*
*/
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <unistd.h>
#include <linux/ipv6.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <sys/epoll.h>
#include "passt.h"
/**
* csum_fold() - Fold long sum for IP and TCP checksum
@ -50,7 +61,45 @@ uint16_t csum_ip4(void *buf, size_t len)
return ~csum_fold(sum);
}
unsigned char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto)
/**
* csum_ipv4() - Calculate TCP checksum for IPv4 and set in place
* @iph: Packet buffer, IP header
*/
void csum_tcp4(struct iphdr *iph)
{
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
uint16_t tlen = ntohs(iph->tot_len) - iph->ihl * 4, *p = (uint16_t *)th;
uint32_t sum = 0;
sum += (iph->saddr >> 16) & 0xffff;
sum += iph->saddr & 0xffff;
sum += (iph->daddr >> 16) & 0xffff;
sum += iph->daddr & 0xffff;
sum += htons(IPPROTO_TCP);
sum += htons(tlen);
th->check = 0;
while (tlen > 1) {
sum += *p++;
tlen -= 2;
}
if (tlen > 0) {
sum += *p & htons(0xff00);
}
th->check = (uint16_t)~csum_fold(sum);
}
/**
* ipv6_l4hdr() - Find pointer to L4 header in IPv6 packet and extract protocol
* @ip6h: IPv6 header
* @proto: Filled with L4 protocol number
*
* Return: pointer to L4 header, NULL if not found
*/
char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto)
{
int offset, len, hdrlen;
struct ipv6_opt_hdr *o;
@ -79,9 +128,95 @@ unsigned char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto)
offset;
} else {
*proto = nh;
return (unsigned char *)(ip6h + 1) + offset;
return (char *)(ip6h + 1) + offset;
}
}
return NULL;
}
/**
* sock_l4_add() - Create and bind socket for given L4, add to epoll list
* @c: Execution context
* @v: IP protocol, 4 or 6
* @proto: Protocol number, network order
* @port: Port, network order
*
* Return: newly created socket, -1 on error
*/
int sock_l4_add(struct ctx *c, int v, uint16_t proto, uint16_t port)
{
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = port,
.sin_addr = { .s_addr = INADDR_ANY },
};
struct sockaddr_in6 addr6 = {
.sin6_family = AF_INET6,
.sin6_port = port,
.sin6_addr = IN6ADDR_ANY_INIT,
};
struct epoll_event ev = { 0 };
const struct sockaddr *sa;
int fd, sl;
if (proto != IPPROTO_TCP && proto != IPPROTO_UDP)
return -1; /* Not implemented. */
fd = socket(v == 4 ? AF_INET : AF_INET6,
proto == IPPROTO_TCP ? SOCK_STREAM : SOCK_DGRAM, proto);
if (fd < 0) {
perror("L4 socket");
return -1;
}
if (v == 4) {
sa = (const struct sockaddr *)&addr4;
sl = sizeof(addr4);
} else {
sa = (const struct sockaddr *)&addr6;
sl = sizeof(addr6);
}
if (bind(fd, sa, sl) < 0) {
/* We'll fail to bind to low ports if we don't have enough
* capabilities, and we'll fail to bind on already bound ports,
* this is fine.
*/
close(fd);
return 0;
}
if (proto == IPPROTO_TCP && listen(fd, 128) < 0) {
perror("TCP socket listen");
close(fd);
return -1;
}
ev.events = EPOLLIN;
ev.data.fd = fd;
if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, fd, &ev) == -1) {
perror("L4 epoll_ctl");
return -1;
}
return fd;
}
/**
* timespec_diff_ms() - Report difference in milliseconds between two timestamps
* @a: Minuend timestamp
* @b: Subtrahend timestamp
*
* Return: difference in milliseconds
*/
int timespec_diff_ms(struct timespec *a, struct timespec *b)
{
if (a->tv_nsec < b->tv_nsec) {
return (b->tv_nsec - a->tv_nsec) / 1000 +
(a->tv_sec - b->tv_sec - 1) * 1000;
}
return (a->tv_nsec - b->tv_nsec) / 1000 +
(a->tv_sec - b->tv_sec) * 1000;
}

5
util.h
View file

@ -1,3 +1,6 @@
uint16_t csum_fold(uint32_t sum);
uint16_t csum_ip4(void *buf, size_t len);
unsigned char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto);
void csum_tcp4(struct iphdr *iph);
char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto);
int sock_l4_add(struct ctx *c, int v, uint16_t proto, uint16_t port);
int timespec_diff_ms(struct timespec *a, struct timespec *b);