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https://passt.top/passt
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137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
// SPDX-License-Identifier: AGPL-3.0-or-later
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/* PASST - Plug A Simple Socket Transport
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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 <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 <arpa/inet.h>
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#include "passt.h"
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#include "util.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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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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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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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, &c->gw6, sizeof(c->gw6)); /* 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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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(3600);
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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; /* 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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*p++ = 25; /* RDNS */
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*p++ = 3; /* length */
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p += 2;
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*(uint32_t *)p = htonl(60); /* lifetime */
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p += 4;
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memcpy(p, &c->dns6, 16); /* address */
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p += 16;
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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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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_ip4(ip6hr, sizeof(*ip6hr) +
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sizeof(*ihr) + len);
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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->fd_unix, 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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