105b916361
This is a reimplementation, partially building on the earlier draft, that uses L4 sockets (SOCK_DGRAM, SOCK_STREAM) instead of SOCK_RAW, providing L4-L2 translation functionality without requiring any security capability. Conceptually, this follows the design presented at: https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Networking.md The most significant novelty here comes from TCP and UDP translation layers. In particular, the TCP state and translation logic follows the intent of being minimalistic, without reimplementing a full TCP stack in either direction, and synchronising as much as possible the TCP dynamic and flows between guest and host kernel. Another important introduction concerns addressing, port translation and forwarding. The Layer 4 implementations now attempt to bind on all unbound ports, in order to forward connections in a transparent way. While at it: - the qemu 'tap' back-end can't be used as-is by qrap anymore, because of explicit checks now introduced in qemu to ensure that the corresponding file descriptor is actually a tap device. For this reason, qrap now operates on a 'socket' back-end type, accounting for and building the additional header reporting frame length - provide a demo script that sets up namespaces, addresses and routes, and starts the daemon. A virtual machine started in the network namespace, wrapped by qrap, will now directly interface with passt and communicate using Layer 4 sockets provided by the host kernel. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
136 lines
3.2 KiB
C
136 lines
3.2 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, unsigned len, struct ethhdr *eh)
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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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fprintf(stderr, "NDP: received NS, sending NA\n");
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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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fprintf(stderr, "NDP: received RS, sending RA\n");
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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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