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// 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"
/* Indexed by ICMP echo identifier */
static int icmp_s_v4[USHRT_MAX];
static int icmp_s_v6[USHRT_MAX];
/**
* icmp_sock_handler() - Handle new data from socket
* @c: Execution context
* @s: File descriptor number for socket
* @events: epoll events bitmap
* @pkt_buf: Buffer to receive packets, currently unused
* @now: Current timestamp, unused
*/
void icmp_sock_handler(struct ctx *c, int s, uint32_t events, char *pkt_buf,
struct timespec *now)
{
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;
(void)pkt_buf;
(void)now;
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
* @msg: Input message
* @count: Message count (always 1 for ICMP)
* @now: Current timestamp, unused
*
* Return: count of consumed packets (always 1, even if malformed)
*/
int icmp_tap_handler(struct ctx *c, int af, void *addr,
struct tap_msg *msg, int count, struct timespec *now)
{
int s;
(void)count;
(void)now;
(void)c;
if (af == AF_INET) {
struct icmphdr *ih = (struct icmphdr *)msg[0].l4h;
struct sockaddr_in sa = {
.sin_family = AF_INET,
.sin_addr = { .s_addr = INADDR_ANY },
.sin_port = ih->un.echo.id,
};
if (msg[0].l4_len < sizeof(*ih) || ih->type != ICMP_ECHO)
return 1;
if ((s = icmp_s_v4[ntohs(ih->un.echo.id)]) < 0)
return 1;
bind(s, (struct sockaddr *)&sa, sizeof(sa));
sa.sin_addr = *(struct in_addr *)addr;
sendto(s, msg[0].l4h, msg[0].l4_len,
MSG_DONTWAIT | MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa));
} else if (af == AF_INET6) {
struct icmp6hdr *ih = (struct icmp6hdr *)msg[0].l4h;
struct sockaddr_in6 sa = {
.sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_ANY_INIT,
.sin6_port = ih->icmp6_identifier,
};
if (msg[0].l4_len < sizeof(*ih) ||
(ih->icmp6_type != 128 && ih->icmp6_type != 129))
return 1;
if ((s = icmp_s_v6[ntohs(ih->icmp6_identifier)]) < 0)
return 1;
bind(s, (struct sockaddr *)&sa, sizeof(sa));
sa.sin6_addr = *(struct in6_addr *)addr;
sendto(s, msg[0].l4h, msg[0].l4_len,
MSG_DONTWAIT | MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa));
}
return 1;
}
/**
* 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)
{
int i, fail = 0;
c->icmp.fd_min = INT_MAX;
c->icmp.fd_max = 0;
if (c->v4) {
for (i = 0; i < USHRT_MAX; i++) {
icmp_s_v4[i] = sock_l4(c, AF_INET, IPPROTO_ICMP, i);
if (icmp_s_v4[i] < 0)
fail = 1;
}
}
if (c->v6) {
for (i = 0; i < USHRT_MAX; i++) {
icmp_s_v6[i] = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, i);
if (icmp_s_v6[i] < 0)
fail = 1;
}
}
if (fail) {
warn("Cannot open some \"ping\" sockets. You might need to:");
warn(" sysctl -w net.ipv4.ping_group_range=\"0 2147483647\"");
warn("...echo requests/replies might fail.");
}
return 0;
}
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