// SPDX-License-Identifier: GPL-2.0-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 <errno.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <stdio.h>
#include <limits.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 <time.h>
#include <linux/icmpv6.h>
#include "packet.h"
#include "util.h"
#include "passt.h"
#include "tap.h"
#include "log.h"
#include "icmp.h"
#define ICMP_ECHO_TIMEOUT 60 /* s, timeout for ICMP socket activity */
#define ICMP_NUM_IDS (1U << 16)
/**
* struct icmp_id_sock - Tracking information for single ICMP echo identifier
* @sock: Bound socket for identifier
* @seq: Last sequence number sent to tap, host order, -1: not sent yet
* @ts: Last associated activity from tap, seconds
*/
struct icmp_id_sock {
int sock;
int seq;
time_t ts;
};
/* Indexed by ICMP echo identifier */
static struct icmp_id_sock icmp_id_map[IP_VERSIONS][ICMP_NUM_IDS];
/* Bitmaps, activity monitoring needed for identifier */
static uint8_t icmp_act[IP_VERSIONS][DIV_ROUND_UP(ICMP_NUM_IDS, 8)];
/**
* icmp_sock_handler() - Handle new data from IPv4 ICMP socket
* @c: Execution context
* @ref: epoll reference
*/
void icmp_sock_handler(const struct ctx *c, union epoll_ref ref)
{
char buf[USHRT_MAX];
struct icmphdr *ih = (struct icmphdr *)buf;
struct sockaddr_in sr;
socklen_t sl = sizeof(sr);
uint16_t seq, id;
ssize_t n;
if (c->no_icmp)
return;
n = recvfrom(ref.fd, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
if (n < 0)
return;
seq = ntohs(ih->un.echo.sequence);
/* Adjust the packet to have the ID the guest was using, rather than the
* host chosen value */
id = ref.icmp.id;
ih->un.echo.id = htons(id);
if (c->mode == MODE_PASTA) {
if (icmp_id_map[V4][id].seq == seq)
return;
icmp_id_map[V4][id].seq = seq;
}
debug("ICMP: echo reply to tap, ID: %i, seq: %i", id, seq);
tap_icmp4_send(c, sr.sin_addr, tap_ip4_daddr(c), buf, n);
}
/**
* icmpv6_sock_handler() - Handle new data from ICMPv6 socket
* @c: Execution context
* @ref: epoll reference
*/
void icmpv6_sock_handler(const struct ctx *c, union epoll_ref ref)
{
char buf[USHRT_MAX];
struct icmp6hdr *ih = (struct icmp6hdr *)buf;
struct sockaddr_in6 sr;
socklen_t sl = sizeof(sr);
uint16_t seq, id;
ssize_t n;
if (c->no_icmp)
return;
n = recvfrom(ref.fd, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
if (n < 0)
return;
seq = ntohs(ih->icmp6_sequence);
/* Adjust the packet to have the ID the guest was using, rather than the
* host chosen value */
id = ref.icmp.id;
ih->icmp6_identifier = htons(id);
/* In PASTA mode, we'll get any reply we send, discard them. */
if (c->mode == MODE_PASTA) {
if (icmp_id_map[V6][id].seq == seq)
return;
icmp_id_map[V6][id].seq = seq;
}
debug("ICMPv6: echo reply to tap, ID: %i, seq: %i", id, seq);
tap_icmp6_send(c, &sr.sin6_addr,
tap_ip6_daddr(c, &sr.sin6_addr), buf, n);
}
/**
* icmp_tap_handler() - Handle packets from tap
* @c: Execution context
* @pif: pif on which the packet is arriving
* @af: Address family, AF_INET or AF_INET6
* @saddr: Source address
* @daddr: Destination address
* @p: Packet pool, single packet with ICMP/ICMPv6 header
* @now: Current timestamp
*
* Return: count of consumed packets (always 1, even if malformed)
*/
int icmp_tap_handler(const struct ctx *c, uint8_t pif, int af,
const void *saddr, const void *daddr,
const struct pool *p, const struct timespec *now)
{
size_t plen;
(void)saddr;
(void)pif;
if (af == AF_INET) {
struct sockaddr_in sa = {
.sin_family = AF_INET,
};
union icmp_epoll_ref iref;
const struct icmphdr *ih;
int id, s;
ih = packet_get(p, 0, 0, sizeof(*ih), &plen);
if (!ih)
return 1;
if (ih->type != ICMP_ECHO)
return 1;
iref.id = id = ntohs(ih->un.echo.id);
if ((s = icmp_id_map[V4][id].sock) < 0) {
s = sock_l4(c, AF_INET, IPPROTO_ICMP, &c->ip4.addr_out,
c->ip4.ifname_out, 0, iref.u32);
if (s < 0)
goto fail_sock;
if (s > FD_REF_MAX) {
close(s);
return 1;
}
icmp_id_map[V4][id].sock = s;
debug("ICMP: new socket %i for echo ID %i", s, id);
}
icmp_id_map[V4][id].ts = now->tv_sec;
bitmap_set(icmp_act[V4], id);
sa.sin_addr = *(struct in_addr *)daddr;
if (sendto(s, ih, sizeof(*ih) + plen, MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa)) < 0) {
debug("ICMP: failed to relay request to socket");
} else {
debug("ICMP: echo request to socket, ID: %i, seq: %i",
id, ntohs(ih->un.echo.sequence));
}
} else if (af == AF_INET6) {
struct sockaddr_in6 sa = {
.sin6_family = AF_INET6,
.sin6_scope_id = c->ifi6,
};
union icmp_epoll_ref iref;
const struct icmp6hdr *ih;
int id, s;
ih = packet_get(p, 0, 0, sizeof(struct icmp6hdr), &plen);
if (!ih)
return 1;
if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
return 1;
iref.id = id = ntohs(ih->icmp6_identifier);
if ((s = icmp_id_map[V6][id].sock) < 0) {
s = sock_l4(c, AF_INET6, IPPROTO_ICMPV6,
&c->ip6.addr_out,
c->ip6.ifname_out, 0, iref.u32);
if (s < 0)
goto fail_sock;
if (s > FD_REF_MAX) {
close(s);
return 1;
}
icmp_id_map[V6][id].sock = s;
debug("ICMPv6: new socket %i for echo ID %i", s, id);
}
icmp_id_map[V6][id].ts = now->tv_sec;
bitmap_set(icmp_act[V6], id);
sa.sin6_addr = *(struct in6_addr *)daddr;
if (sendto(s, ih, sizeof(*ih) + plen, MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa)) < 1) {
debug("ICMPv6: failed to relay request to socket");
} else {
debug("ICMPv6: echo request to socket, ID: %i, seq: %i",
id, ntohs(ih->icmp6_sequence));
}
}
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
* @now: Current timestamp
*/
static void icmp_timer_one(const struct ctx *c, int v6, uint16_t id,
const struct timespec *now)
{
struct icmp_id_sock *id_map = &icmp_id_map[v6 ? V6 : V4][id];
if (now->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 = -1;
id_map->seq = -1;
}
/**
* icmp_timer() - Scan activity bitmap for identifiers with timed events
* @c: Execution context
* @now: Current timestamp
*/
void icmp_timer(const struct ctx *c, const struct timespec *now)
{
long *word, tmp;
unsigned int i;
int n, v6 = 0;
v6:
word = (long *)icmp_act[v6 ? V6 : V4];
for (i = 0; i < ARRAY_SIZE(icmp_act); i += sizeof(long), word++) {
tmp = *word;
while ((n = ffsl(tmp))) {
tmp &= ~(1UL << (n - 1));
icmp_timer_one(c, v6, i * 8 + n - 1, now);
}
}
if (!v6) {
v6 = 1;
goto v6;
}
}
/**
* icmp_init() - Initialise sequences in ID map to -1 (no sequence sent yet)
*/
void icmp_init(void)
{
unsigned i;
for (i = 0; i < ICMP_NUM_IDS; i++) {
icmp_id_map[V4][i].seq = icmp_id_map[V6][i].seq = -1;
icmp_id_map[V4][i].sock = icmp_id_map[V6][i].sock = -1;
}
}