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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
*
* 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 "util.h"
#include "passt.h"
#include "tap.h"
#include "icmp.h"
#define ICMP_ECHO_TIMEOUT 60 /* s, timeout for ICMP socket activity */
/**
* struct icmp_id - Tracking information for single ICMP echo identifier
* @sock: Bound socket for identifier
* @ts: Last associated activity from tap, seconds
* @seq: Last sequence number sent to tap, host order
*/
struct icmp_id {
int sock;
time_t ts;
uint16_t seq;
};
/* Indexed by ICMP echo identifier */
static struct icmp_id icmp_id_map [IP_VERSIONS][USHRT_MAX];
/* Bitmaps, activity monitoring needed for identifier */
static uint8_t icmp_act [IP_VERSIONS][USHRT_MAX / 8];
/**
* icmp_sock_handler() - Handle new data from socket
* @c: Execution context
* @ref: epoll reference
* @events: epoll events bitmap
* @now: Current timestamp, unused
*/
void icmp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
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;
socklen_t sl = sizeof(sr);
char buf[USHRT_MAX];
uint16_t seq, id;
ssize_t n;
(void)events;
(void)now;
n = recvfrom(ref.s, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
if (n < 0)
return;
if (ref.icmp.v6) {
struct sockaddr_in6 *sr6 = (struct sockaddr_in6 *)&sr;
struct icmp6hdr *ih = (struct icmp6hdr *)buf;
/* In PASTA mode, we'll get any reply we send, discard them. */
if (c->mode == MODE_PASTA) {
seq = ntohs(ih->icmp6_sequence);
id = ntohs(ih->icmp6_identifier);
if (icmp_id_map[V6][id].seq == seq)
return;
icmp_id_map[V6][id].seq = seq;
}
tap_ip_send(c, &sr6->sin6_addr, IPPROTO_ICMPV6, buf, n);
} else {
struct sockaddr_in *sr4 = (struct sockaddr_in *)&sr;
struct icmphdr *ih = (struct icmphdr *)buf;
if (c->mode == MODE_PASTA) {
seq = ntohs(ih->un.echo.sequence);
id = ntohs(ih->un.echo.id);
if (icmp_id_map[V4][id].seq == seq)
return;
icmp_id_map[V4][id].seq = seq;
}
memcpy(&a6.s6_addr[12], &sr4->sin_addr, sizeof(sr4->sin_addr));
tap_ip_send(c, &a6, IPPROTO_ICMP, 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
*
* 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)
{
(void)count;
if (af == AF_INET) {
struct icmphdr *ih = (struct icmphdr *)msg[0].l4h;
union icmp_epoll_ref iref = { .v6 = 0 };
struct sockaddr_in sa = {
.sin_family = AF_INET,
.sin_addr = { .s_addr = INADDR_ANY },
.sin_port = ih->un.echo.id,
};
int id, s;
if (msg[0].l4_len < sizeof(*ih) || ih->type != ICMP_ECHO)
return 1;
id = ntohs(ih->un.echo.id);
if ((s = icmp_id_map[V4][id].sock) <= 0) {
s = sock_l4(c, AF_INET, IPPROTO_ICMP, id, 0, iref.u32);
if (s < 0)
goto fail_sock;
icmp_id_map[V4][id].sock = s;
}
icmp_id_map[V4][id].ts = now->tv_sec;
bitmap_set(icmp_act[V4], id);
sa.sin_addr = *(struct in_addr *)addr;
sendto(s, msg[0].l4h, msg[0].l4_len, MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa));
} else if (af == AF_INET6) {
struct icmp6hdr *ih = (struct icmp6hdr *)msg[0].l4h;
union icmp_epoll_ref iref = { .v6 = 1 };
struct sockaddr_in6 sa = {
.sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_ANY_INIT,
.sin6_port = ih->icmp6_identifier,
};
int id, s;
if (msg[0].l4_len < sizeof(*ih) ||
(ih->icmp6_type != 128 && ih->icmp6_type != 129))
return 1;
id = ntohs(ih->icmp6_identifier);
if ((s = icmp_id_map[V6][id].sock) <= 0) {
s = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, id, 0,
iref.u32);
if (s < 0)
goto fail_sock;
icmp_id_map[V6][id].sock = s;
}
icmp_id_map[V6][id].ts = now->tv_sec;
bitmap_set(icmp_act[V6], id);
sa.sin6_addr = *(struct in6_addr *)addr;
sendto(s, msg[0].l4h, msg[0].l4_len, MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa));
}
return 1;
fail_sock:
warn("Cannot open \"ping\" socket. You might need to:");
warn(" sysctl -w net.ipv4.ping_group_range=\"0 2147483647\"");
warn("...echo requests/replies will fail.");
return 1;
}
/**
* icmp_timer_one() - Handler for timed events related to a given identifier
* @c: Execution context
* @v6: Set for IPv6 echo identifier bindings
* @id: Echo identifier, host order
* @ts: Timestamp from caller
*/
static void icmp_timer_one(struct ctx *c, int v6, uint16_t id,
struct timespec *ts)
{
struct icmp_id *id_map = &icmp_id_map[v6 ? V6 : V4][id];
if (ts->tv_sec - id_map->ts <= ICMP_ECHO_TIMEOUT)
return;
bitmap_clear(icmp_act[v6 ? V6 : V4], id);
epoll_ctl(c->epollfd, EPOLL_CTL_DEL, id_map->sock, NULL);
close(id_map->sock);
id_map->sock = 0;
}
/**
* icmp_timer() - Scan activity bitmap for identifiers with timed events
* @c: Execution context
* @ts: Timestamp from caller
*/
void icmp_timer(struct ctx *c, struct timespec *ts)
{
long *word, tmp;
unsigned int i;
int n, v6 = 0;
v6:
word = (long *)icmp_act[v6 ? V6 : V4];
for (i = 0; i < sizeof(icmp_act[0]) / sizeof(long); i++, word++) {
tmp = *word;
while ((n = ffsl(tmp))) {
tmp &= ~(1UL << (n - 1));
icmp_timer_one(c, v6, i * sizeof(long) * 8 + n - 1, ts);
}
}
if (!v6) {
v6 = 1;
goto v6;
}
}
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