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passt: Introduce ICMP echo proxy

Browse source 
It's nice to be able to confirm connectivity using ICMP or ICMPv6
echo requests, and "ping" sockets on Linux (IPPROTO_ICMP datagram)
allow us to do that without any special capability.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-03-17 10:57:44 +01:00
parent d32edee60a
commit 1d807fc720
7 changed files with 183 additions and 11 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 siphash.c siphash.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 siphash.c tap.c tcp.c udp.c util.c -o passt
passt: passt.c passt.h arp.c arp.h dhcp.c dhcp.h ndp.c ndp.h siphash.c siphash.h tap.c tap.h icmp.c icmp.h tcp.c tcp.h udp.c udp.h util.c util.h
$(CC) $(CFLAGS) passt.c arp.c dhcp.c ndp.c siphash.c tap.c icmp.c tcp.c udp.c util.c -o passt
qrap: qrap.c passt.h
$(CC) $(CFLAGS) qrap.c -o qrap

1
doc/demo.sh
View file

@ -74,6 +74,7 @@ sysctl -w net.ipv6.conf.all.forwarding=1
ethtool -K veth_passt tx off
ip netns exec passt ethtool -K veth_passt tx off
ip netns exec passt sysctl -w net.ipv4.ping_group_range="0 2147483647"
ulimit -n 300000

136
icmp.c Normal file
View file

@ -0,0 +1,136 @@
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* icmp.c - ICMP/ICMPv6 echo proxy
*
* Copyright (c) 2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
#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/icmp.h>
#include <linux/icmpv6.h>
#include <time.h>
#include "passt.h"
#include "tap.h"
#include "util.h"
#include "icmp.h"
/**
* icmp_sock_handler() - Handle new data from socket
* @c: Execution context
* @s: File descriptor number for socket
* @events: epoll events bitmap
*/
void icmp_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];
ssize_t n;
(void)events;
n = recvfrom(s, buf, sizeof(buf), MSG_DONTWAIT,
(struct sockaddr *)&sr, &slen);
if (n < 0)
return;
if (getsockname(s, (struct sockaddr *)&sl, &slen))
return;
if (sl.ss_family == AF_INET) {
struct sockaddr_in *sr4 = (struct sockaddr_in *)&sr;
memcpy(&a6.s6_addr[12], &sr4->sin_addr, sizeof(sr4->sin_addr));
tap_ip_send(c, &a6, IPPROTO_ICMP, buf, n);
} else if (sl.ss_family == AF_INET6) {
struct sockaddr_in6 *sr6 = (struct sockaddr_in6 *)&sr;
tap_ip_send(c, &sr6->sin6_addr, IPPROTO_ICMPV6, buf, n);
}
}
/**
* icmp_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 icmp_tap_handler(struct ctx *c, int af, void *addr, char *in, size_t len)
{
if (af == AF_INET) {
struct icmphdr *ih = (struct icmphdr *)in;
struct sockaddr_in sa = {
.sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_ANY),
};
if (len < sizeof(*ih) || ih->type != ICMP_ECHO)
return;
sa.sin_port = ih->un.echo.id;
bind(c->icmp.s4, (struct sockaddr *)&sa, sizeof(sa));
sa.sin_addr = *(struct in_addr *)addr;
sendto(c->icmp.s4, in, len, MSG_DONTWAIT,
(struct sockaddr *)&sa, sizeof(sa));
} else if (af == AF_INET6) {
struct sockaddr_in6 sa = {
.sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_ANY_INIT,
};
struct icmp6hdr *ih = (struct icmp6hdr *)in;
if (len < sizeof(*ih) ||
(ih->icmp6_type != 128 && ih->icmp6_type != 129))
return;
sa.sin6_port = ih->icmp6_identifier;
bind(c->icmp.s6, (struct sockaddr *)&sa, sizeof(sa));
sa.sin6_addr = *(struct in6_addr *)addr;
sendto(c->icmp.s6, in, len, MSG_DONTWAIT | MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa));
}
}
/**
* icmp_sock_init() - Create ICMP, ICMPv6 sockets for echo requests and replies
* @c: Execution context
*
* Return: 0 on success, -1 on failure
*/
int icmp_sock_init(struct ctx *c)
{
if (c->v4 && (c->icmp.s4 = sock_l4_add(c, 4, IPPROTO_ICMP, 0)) < 0)
return -1;
if (c->v6 && (c->icmp.s6 = sock_l4_add(c, 6, IPPROTO_ICMPV6, 0)) < 0)
return -1;
return 0;
}

20
icmp.h Normal file
View file

@ -0,0 +1,20 @@
#ifndef ICMP_H
#define ICMP_H
struct ctx;
void icmp_sock_handler(struct ctx *c, int s, uint32_t events);
void icmp_tap_handler(struct ctx *c, int af, void *addr, char *in, size_t len);
int icmp_sock_init(struct ctx *c);
/**
* struct icmp_ctx - Execution context for ICMP routines
* @s4: ICMP socket number
* @s6: ICMPv6 socket number
*/
struct icmp_ctx {
int s4;
int s6;
};
#endif /* ICMP_H */

24
passt.c
View file

@ -46,6 +46,7 @@
#include "dhcp.h"
#include "ndp.h"
#include "util.h"
#include "icmp.h"
#include "tcp.h"
#include "udp.h"
@ -335,6 +336,8 @@ static void tap4_handler(struct ctx *c, char *in, size_t len)
tcp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
else if (iph->protocol == IPPROTO_UDP)
udp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
else if (iph->protocol == IPPROTO_ICMP)
icmp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
}
/**
@ -391,6 +394,8 @@ static void tap6_handler(struct ctx *c, char *in, size_t len)
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);
else if (proto == IPPROTO_ICMPV6)
icmp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len);
}
/**
@ -449,15 +454,18 @@ static void sock_handler(struct ctx *c, int fd, uint32_t events)
sl = sizeof(so);
if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &so, &sl) ||
so == SOCK_STREAM) {
fprintf(stderr, "TCP: packet from socket %i\n", fd);
if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &so, &sl))
return;
fprintf(stderr, "%s: packet from socket %i\n",
getprotobynumber(so)->p_name, fd);
if (so == IPPROTO_ICMP || so == IPPROTO_ICMPV6)
icmp_sock_handler(c, fd, events);
else if (so == IPPROTO_TCP)
tcp_sock_handler(c, fd, events);
}
else if (so == SOCK_DGRAM) {
else if (so == IPPROTO_UDP)
udp_sock_handler(c, fd, events);
fprintf(stderr, "UDP: packet from socket %i\n", fd);
}
}
/**
@ -546,7 +554,7 @@ int main(int argc, char **argv)
exit(EXIT_FAILURE);
}
if (tcp_sock_init(&c) || udp_sock_init(&c))
if (icmp_sock_init(&c) || tcp_sock_init(&c) || udp_sock_init(&c))
exit(EXIT_FAILURE);
fd_unix = sock_unix();

2
passt.h
View file

@ -1,5 +1,6 @@
#define UNIX_SOCK_PATH "/tmp/passt.socket"
#include "icmp.h"
#include "tcp.h"
/**
@ -39,5 +40,6 @@ struct ctx {
char ifn[IF_NAMESIZE];
struct icmp_ctx icmp;
struct tcp_ctx tcp;
};

7
util.c
View file

@ -160,7 +160,8 @@ int sock_l4_add(struct ctx *c, int v, uint16_t proto, uint16_t port)
const struct sockaddr *sa;
int fd, sl, one = 1;
if (proto != IPPROTO_TCP && proto != IPPROTO_UDP)
if (proto != IPPROTO_TCP && proto != IPPROTO_UDP &&
proto != IPPROTO_ICMP && proto != IPPROTO_ICMPV6)
return -1; /* Not implemented. */
fd = socket(v == 4 ? AF_INET : AF_INET6,
@ -170,6 +171,9 @@ int sock_l4_add(struct ctx *c, int v, uint16_t proto, uint16_t port)
return -1;
}
if (proto == IPPROTO_ICMP || proto == IPPROTO_ICMPV6)
goto epoll_add;
if (v == 4) {
sa = (const struct sockaddr *)&addr4;
sl = sizeof(addr4);
@ -195,6 +199,7 @@ int sock_l4_add(struct ctx *c, int v, uint16_t proto, uint16_t port)
return -1;
}
epoll_add:
ev.events = EPOLLIN;
ev.data.fd = fd;
if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, fd, &ev) == -1) {