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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
*
* ndp.c - NDP support for PASST
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/if_ether.h>
#include <linux/icmpv6.h>
#include "checksum.h"
#include "util.h"
#include "passt.h"
#include "tap.h"
#define RS 133
#define RA 134
#define NS 135
#define NA 136
/**
* ndp() - Check for NDP solicitations, reply as needed
* @c: Execution context
* @ih: ICMPv6 header
* @eh_source: Source Ethernet address
* @saddr Source IPv6 address
*
* Return: 0 if not handled here, 1 if handled, -1 on failure
*/
int ndp(struct ctx *c, const struct icmp6hdr *ih,
const unsigned char *eh_source, const struct in6_addr *saddr)
{
char buf[BUFSIZ] = { 0 };
struct ipv6hdr *ip6hr;
struct icmp6hdr *ihr;
struct ethhdr *ehr;
unsigned char *p;
size_t len;
if (ih->icmp6_type < RS || ih->icmp6_type > NA)
return 0;
if (c->no_ndp)
return 1;
ehr = (struct ethhdr *)buf;
ip6hr = (struct ipv6hdr *)(ehr + 1);
ihr = (struct icmp6hdr *)(ip6hr + 1);
if (ih->icmp6_type == NS) {
if (IN6_IS_ADDR_UNSPECIFIED(saddr))
return 1;
info("NDP: received NS, sending NA");
ihr->icmp6_type = NA;
ihr->icmp6_code = 0;
ihr->icmp6_router = 1;
ihr->icmp6_solicited = 1;
ihr->icmp6_override = 1;
p = (unsigned char *)(ihr + 1);
memcpy(p, ih + 1, sizeof(struct in6_addr)); /* target address */
p += 16;
*p++ = 2; /* target ll */
*p++ = 1; /* length */
memcpy(p, c->mac, ETH_ALEN);
p += 6;
} else if (ih->icmp6_type == RS) {
size_t dns_s_len = 0;
int i, n;
if (c->no_ra)
return 1;
info("NDP: received RS, sending RA");
ihr->icmp6_type = RA;
ihr->icmp6_code = 0;
ihr->icmp6_hop_limit = 255;
ihr->icmp6_rt_lifetime = htons(9000);
ihr->icmp6_addrconf_managed = 1;
p = (unsigned char *)(ihr + 1);
p += 8; /* reachable, retrans time */
*p++ = 3; /* prefix */
*p++ = 4; /* length */
*p++ = 64; /* prefix length */
*p++ = 0xc0; /* prefix flags: L, A */
*(uint32_t *)p = htonl(3600); /* lifetime */
p += 4;
*(uint32_t *)p = htonl(3600); /* preferred lifetime */
p += 8;
memcpy(p, &c->ip6.addr, 8); /* prefix */
p += 16;
if (c->mtu != -1) {
*p++ = 5; /* type */
*p++ = 1; /* length */
p += 2; /* reserved */
*(uint32_t *)p = htonl(c->mtu); /* MTU */
p += 4;
}
if (c->no_dhcp_dns)
goto dns_done;
for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[n]); n++);
if (n) {
*p++ = 25; /* RDNSS */
*p++ = 1 + 2 * n; /* length */
p += 2; /* reserved */
*(uint32_t *)p = htonl(60); /* lifetime */
p += 4;
for (i = 0; i < n; i++) {
memcpy(p, &c->ip6.dns[i], 16); /* address */
p += 16;
}
for (n = 0; *c->dns_search[n].n; n++)
dns_s_len += strlen(c->dns_search[n].n) + 2;
}
if (!c->no_dhcp_dns_search && dns_s_len) {
*p++ = 31; /* DNSSL */
*p++ = (dns_s_len + 8 - 1) / 8 + 1; /* length */
p += 2; /* reserved */
*(uint32_t *)p = htonl(60); /* lifetime */
p += 4;
for (i = 0; i < n; i++) {
char *dot;
*(p++) = '.';
strncpy((char *)p, c->dns_search[i].n,
sizeof(buf) -
((intptr_t)p - (intptr_t)buf));
for (dot = (char *)p - 1; *dot; dot++) {
if (*dot == '.')
*dot = strcspn(dot + 1, ".");
}
p += strlen(c->dns_search[i].n);
*(p++) = 0;
}
memset(p, 0, 8 - dns_s_len % 8); /* padding */
p += 8 - dns_s_len % 8;
}
dns_done:
*p++ = 1; /* source ll */
*p++ = 1; /* length */
memcpy(p, c->mac, ETH_ALEN);
p += 6;
} else {
return 1;
}
len = (uintptr_t)p - (uintptr_t)ihr - sizeof(*ihr);
if (IN6_IS_ADDR_LINKLOCAL(saddr))
c->ip6.addr_ll_seen = *saddr;
else
c->ip6.addr_seen = *saddr;
ip6hr->daddr = *saddr;
if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
ip6hr->saddr = c->ip6.gw;
else
ip6hr->saddr = c->ip6.addr_ll;
ip6hr->payload_len = htons(sizeof(*ihr) + len);
ip6hr->hop_limit = IPPROTO_ICMPV6;
ihr->icmp6_cksum = 0;
ihr->icmp6_cksum = csum_unaligned(ip6hr, sizeof(*ip6hr) +
sizeof(*ihr) + len, 0);
ip6hr->version = 6;
ip6hr->nexthdr = IPPROTO_ICMPV6;
ip6hr->hop_limit = 255;
len += sizeof(*ehr) + sizeof(*ip6hr) + sizeof(*ihr);
memcpy(ehr->h_dest, eh_source, ETH_ALEN);
memcpy(ehr->h_source, c->mac, ETH_ALEN);
ehr->h_proto = htons(ETH_P_IPV6);
if (tap_send(c, ehr, len, 0) < 0)
perror("NDP: send");
return 1;
}
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