1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
| | // 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"
#include "log.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);
csum_icmp6(ihr, &ip6hr->saddr, &ip6hr->daddr, ihr + 1, len);
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)
perror("NDP: send");
return 1;
}
|