1/* SPDX-License-Identifier: BSD-2-Clause */
2/*
3 * dhcpcd - DHCP client daemon
4 * Copyright (c) 2006-2023 Roy Marples <roy@marples.name>
5 * All rights reserved
6
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#define	UUID_LEN	36
30#define	DUID_TIME_EPOCH 946684800
31
32#include <sys/param.h>
33#include <sys/socket.h>
34#include <sys/types.h>
35#ifdef BSD
36#  include <sys/sysctl.h>
37#endif
38
39#include <arpa/inet.h>
40
41#include <net/if.h>
42#include <net/if_arp.h>
43
44#include <errno.h>
45#include <stdint.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49#include <time.h>
50#include <unistd.h>
51
52#include "common.h"
53#include "dhcpcd.h"
54#include "duid.h"
55#include "logerr.h"
56
57/*
58 * Machine, system or product UUIDs are not guaranteed unique.
59 * Let's not use them by default.
60 */
61#ifdef USE_MACHINE_UUID
62static size_t
63duid_machineuuid(char *uuid, size_t uuid_len)
64{
65	int r;
66	size_t len = uuid_len;
67
68#if defined(HW_UUID) /* OpenBSD */
69	int mib[] = { CTL_HW, HW_UUID };
70
71	r = sysctl(mib, sizeof(mib)/sizeof(mib[0]), uuid, &len, NULL, 0);
72#elif defined(KERN_HOSTUUID) /* FreeBSD */
73	int mib[] = { CTL_KERN, KERN_HOSTUUID };
74
75	r = sysctl(mib, sizeof(mib)/sizeof(mib[0]), uuid, &len, NULL, 0);
76#elif defined(__NetBSD__)
77	r = sysctlbyname("machdep.dmi.system-uuid", uuid, &len, NULL, 0);
78#elif defined(__linux__)
79	FILE *fp;
80
81	fp = fopen("/sys/class/dmi/id/product_uuid", "r");
82	if (fp == NULL)
83		return 0;
84	if (fgets(uuid, (int)uuid_len, fp) == NULL) {
85		fclose(fp);
86		return 0;
87	}
88	len = strlen(uuid) + 1;
89	fclose(fp);
90	r = len == 1 ? -1 : 0;
91#else
92	UNUSED(uuid);
93	r = -1;
94	errno = ENOSYS;
95#endif
96
97	if (r == -1)
98		return 0;
99	return len;
100}
101
102static size_t
103duid_make_uuid(uint8_t *d)
104{
105	uint16_t type = htons(DUID_UUID);
106	char uuid[UUID_LEN + 1];
107	size_t l;
108
109	if (duid_machineuuid(uuid, sizeof(uuid)) != sizeof(uuid))
110		return 0;
111
112	/* All zeros UUID is not valid */
113	if (strcmp("00000000-0000-0000-0000-000000000000", uuid) == 0)
114		return 0;
115
116	memcpy(d, &type, sizeof(type));
117	l = sizeof(type);
118	d += sizeof(type);
119	l += hwaddr_aton(d, uuid);
120	return l;
121}
122#endif
123
124size_t
125duid_make(void *d, const struct interface *ifp, uint16_t type)
126{
127	uint8_t *p;
128	uint16_t u16;
129	time_t t;
130	uint32_t u32;
131
132	if (ifp->hwlen == 0)
133		return 0;
134
135	p = d;
136	u16 = htons(type);
137	memcpy(p, &u16, sizeof(u16));
138	p += sizeof(u16);
139	u16 = htons(ifp->hwtype);
140	memcpy(p, &u16, sizeof(u16));
141	p += sizeof(u16);
142	if (type == DUID_LLT) {
143		/* time returns seconds from jan 1 1970, but DUID-LLT is
144		 * seconds from jan 1 2000 modulo 2^32 */
145		t = time(NULL) - DUID_TIME_EPOCH;
146		u32 = htonl((uint32_t)t & 0xffffffff);
147		memcpy(p, &u32, sizeof(u32));
148		p += sizeof(u32);
149	}
150	/* Finally, add the MAC address of the interface */
151	memcpy(p, ifp->hwaddr, ifp->hwlen);
152	p += ifp->hwlen;
153	return (size_t)(p - (uint8_t *)d);
154}
155
156#define DUID_STRLEN DUID_LEN * 3
157static size_t
158duid_get(struct dhcpcd_ctx *ctx, const struct interface *ifp)
159{
160	uint8_t *data;
161	size_t len, slen;
162	char line[DUID_STRLEN];
163	const struct interface *ifp2;
164
165	/* If we already have a DUID then use it as it's never supposed
166	 * to change once we have one even if the interfaces do */
167	if ((len = dhcp_read_hwaddr_aton(ctx, &data, DUID)) != 0) {
168		if (len <= DUID_LEN) {
169			ctx->duid = data;
170			return len;
171		}
172		logerrx("DUID too big (max %u): %s", DUID_LEN, DUID);
173		/* Keep the buffer, will assign below. */
174	} else {
175		if (errno != ENOENT)
176			logerr("%s", DUID);
177		if ((data = malloc(DUID_LEN)) == NULL) {
178			logerr(__func__);
179			return 0;
180		}
181	}
182
183	/* No file? OK, lets make one based the machines UUID */
184	if (ifp == NULL) {
185#ifdef USE_MACHINE_UUID
186		if (ctx->duid_type != DUID_DEFAULT &&
187		    ctx->duid_type != DUID_UUID)
188			len = 0;
189		else
190			len = duid_make_uuid(data);
191		if (len == 0)
192			free(data);
193		else
194			ctx->duid = data;
195		return len;
196#else
197		free(data);
198		return 0;
199#endif
200	}
201
202	/* Regardless of what happens we will create a DUID to use. */
203	ctx->duid = data;
204
205	/* No UUID? OK, lets make one based on our interface */
206	if (ifp->hwlen == 0) {
207		logwarnx("%s: does not have hardware address", ifp->name);
208		TAILQ_FOREACH(ifp2, ifp->ctx->ifaces, next) {
209			if (ifp2->hwlen != 0)
210				break;
211		}
212		if (ifp2) {
213			ifp = ifp2;
214			logwarnx("picked interface %s to generate a DUID",
215			    ifp->name);
216		} else {
217			if (ctx->duid_type != DUID_LL)
218				logwarnx("no interfaces have a fixed hardware "
219				    "address");
220			return duid_make(data, ifp, DUID_LL);
221		}
222	}
223
224	len = duid_make(data, ifp,
225	    ctx->duid_type == DUID_LL ? DUID_LL : DUID_LLT);
226	hwaddr_ntoa(data, len, line, sizeof(line));
227	slen = strlen(line);
228	if (slen < sizeof(line) - 2) {
229		line[slen++] = '\n';
230		line[slen] = '\0';
231	}
232	if (dhcp_writefile(ctx, DUID, 0640, line, slen) == -1) {
233		logerr("%s: cannot write duid", __func__);
234		if (ctx->duid_type != DUID_LL)
235			return duid_make(data, ifp, DUID_LL);
236	}
237	return len;
238}
239
240size_t
241duid_init(struct dhcpcd_ctx *ctx, const struct interface *ifp)
242{
243
244	if (ctx->duid == NULL)
245		ctx->duid_len = duid_get(ctx, ifp);
246	return ctx->duid_len;
247}
248