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Seen while testing: lifetime expires while we're flooding a tap interface with UDP packets, the router advertisement comes too late, and the kernel drops the default router in the namespace. This should only affect testing, so go for the maximum allowed value, that is, 9000 seconds. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
207 lines
4.7 KiB
C
207 lines
4.7 KiB
C
// SPDX-License-Identifier: AGPL-3.0-or-later
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/* PASST - Plug A Simple Socket Transport
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* for qemu/UNIX domain socket mode
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*
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* PASTA - Pack A Subtle Tap Abstraction
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* for network namespace/tap device mode
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*
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* ndp.c - NDP support for PASST
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*
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* Copyright (c) 2020-2021 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*
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*/
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#include <stdio.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <string.h>
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#include <arpa/inet.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/icmpv6.h>
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#include <linux/udp.h>
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#include <net/if.h>
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#include <net/if_arp.h>
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#include "checksum.h"
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#include "util.h"
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#include "passt.h"
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#include "tap.h"
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#define RS 133
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#define RA 134
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#define NS 135
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#define NA 136
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/**
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* ndp() - Check for NDP solicitations, reply as needed
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* @c: Execution context
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* @len: Total L2 packet length
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* @eh: Packet buffer, Ethernet header
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*
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* Return: 0 if not handled here, 1 if handled, -1 on failure
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*/
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int ndp(struct ctx *c, struct ethhdr *eh, size_t len)
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{
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struct ethhdr *ehr;
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struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1), *ip6hr;
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struct icmp6hdr *ih, *ihr;
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char buf[BUFSIZ] = { 0 };
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uint8_t proto, *p;
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if (len < sizeof(*ehr) + sizeof(*ip6h) + sizeof(ih))
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return 0;
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ih = (struct icmp6hdr *)ipv6_l4hdr(ip6h, &proto);
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if (!ih)
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return -1;
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if (proto != IPPROTO_ICMPV6 ||
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ih->icmp6_type < RS || ih->icmp6_type > NA)
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return 0;
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if (c->no_ndp)
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return 1;
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ehr = (struct ethhdr *)buf;
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ip6hr = (struct ipv6hdr *)(ehr + 1);
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ihr = (struct icmp6hdr *)(ip6hr + 1);
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if (ih->icmp6_type == NS) {
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if (len < sizeof(*ehr) + sizeof(*ip6h) + sizeof(ih) +
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sizeof(struct in6_addr))
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return -1;
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info("NDP: received NS, sending NA");
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ihr->icmp6_type = NA;
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ihr->icmp6_code = 0;
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ihr->icmp6_router = 1;
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ihr->icmp6_solicited = 1;
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ihr->icmp6_override = 1;
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p = (unsigned char *)(ihr + 1);
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memcpy(p, ih + 1, sizeof(struct in6_addr)); /* target address */
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p += 16;
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*p++ = 2; /* target ll */
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*p++ = 1; /* length */
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memcpy(p, c->mac, ETH_ALEN);
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p += 6;
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} else if (ih->icmp6_type == RS) {
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size_t len = 0;
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int i, n;
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if (c->no_ra)
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return 1;
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info("NDP: received RS, sending RA");
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ihr->icmp6_type = RA;
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ihr->icmp6_code = 0;
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ihr->icmp6_rt_lifetime = htons(9000);
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ihr->icmp6_addrconf_managed = 1;
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p = (unsigned char *)(ihr + 1);
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p += 8; /* reachable, retrans time */
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*p++ = 3; /* prefix */
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*p++ = 4; /* length */
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*p++ = 64; /* prefix length */
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*p++ = 0xc0; /* prefix flags: L, A */
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*(uint32_t *)p = htonl(3600); /* lifetime */
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p += 4;
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*(uint32_t *)p = htonl(3600); /* preferred lifetime */
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p += 8;
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memcpy(p, &c->addr6, 8); /* prefix */
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p += 16;
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if (c->mtu != -1) {
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*p++ = 5; /* type */
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*p++ = 1; /* length */
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p += 2; /* reserved */
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*(uint32_t *)p = htonl(c->mtu); /* MTU */
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p += 4;
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}
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for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->dns6[n]); n++);
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if (n) {
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*p++ = 25; /* RDNSS */
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*p++ = 1 + 2 * n; /* length */
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p += 2; /* reserved */
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*(uint32_t *)p = htonl(60); /* lifetime */
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p += 4;
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for (i = 0; i < n; i++) {
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memcpy(p, &c->dns6[i], 16); /* address */
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p += 16;
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}
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}
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for (n = 0; *c->dns_search[n].n; n++)
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len += strlen(c->dns_search[n].n) + 2;
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if (len) {
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*p++ = 31; /* DNSSL */
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*p++ = (len + 8 - 1) / 8 + 1; /* length */
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p += 2; /* reserved */
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*(uint32_t *)p = htonl(60); /* lifetime */
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p += 4;
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for (i = 0; i < n; i++) {
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char *dot;
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*(p++) = '.';
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strncpy((char *)p, c->dns_search[i].n,
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sizeof(buf) -
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((intptr_t)p - (intptr_t)buf));
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for (dot = (char *)p - 1; *dot; dot++) {
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if (*dot == '.')
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*dot = strcspn(dot + 1, ".");
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}
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p += strlen(c->dns_search[i].n);
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*(p++) = 0;
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}
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memset(p, 0, 8 - len % 8); /* padding */
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p += 8 - len % 8;
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}
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*p++ = 1; /* source ll */
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*p++ = 1; /* length */
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memcpy(p, c->mac, ETH_ALEN);
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p += 6;
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} else {
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return 1;
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}
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len = (uintptr_t)p - (uintptr_t)ihr - sizeof(*ihr);
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if (IN6_IS_ADDR_LINKLOCAL(&ip6h->saddr))
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c->addr6_ll_seen = ip6h->saddr;
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else
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c->addr6_seen = ip6h->saddr;
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ip6hr->daddr = ip6h->saddr;
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ip6hr->saddr = c->gw6;
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ip6hr->payload_len = htons(sizeof(*ihr) + len);
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ip6hr->hop_limit = IPPROTO_ICMPV6;
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ihr->icmp6_cksum = 0;
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ihr->icmp6_cksum = csum_unaligned(ip6hr, sizeof(*ip6hr) +
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sizeof(*ihr) + len, 0);
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ip6hr->version = 6;
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ip6hr->nexthdr = IPPROTO_ICMPV6;
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ip6hr->hop_limit = 255;
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len += sizeof(*ehr) + sizeof(*ip6hr) + sizeof(*ihr);
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memcpy(ehr->h_dest, eh->h_source, ETH_ALEN);
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memcpy(ehr->h_source, c->mac, ETH_ALEN);
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ehr->h_proto = htons(ETH_P_IPV6);
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if (tap_send(c, ehr, len, 0) < 0)
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perror("NDP: send");
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return 1;
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}
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