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
62 static size_t
duid_machineuuid(char * uuid,size_t uuid_len)63 duid_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
102 static size_t
duid_make_uuid(uint8_t * d)103 duid_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
124 size_t
duid_make(void * d,const struct interface * ifp,uint16_t type)125 duid_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
157 static size_t
duid_get(struct dhcpcd_ctx * ctx,const struct interface * ifp)158 duid_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
240 size_t
duid_init(struct dhcpcd_ctx * ctx,const struct interface * ifp)241 duid_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