1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3 * CDDL HEADER START
4 *
5 * The contents of this file are subject to the terms of the
6 * Common Development and Distribution License (the "License").
7 * You may not use this file except in compliance with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or https://opensource.org/licenses/CDDL-1.0.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright (c) 2017, Lawrence Livermore National Security, LLC.
24 */
25
26 #include <fcntl.h>
27 #include <stdlib.h>
28 #include <stdio.h>
29 #include <sys/types.h>
30 #include <sys/stat.h>
31 #include <sys/systeminfo.h>
32
33 static unsigned long
get_spl_hostid(void)34 get_spl_hostid(void)
35 {
36 FILE *f;
37 unsigned long hostid;
38 char *env;
39
40 /*
41 * Allow the hostid to be subverted for testing.
42 */
43 env = getenv("ZFS_HOSTID");
44 if (env)
45 return (strtoull(env, NULL, 0));
46
47 f = fopen("/proc/sys/kernel/spl/hostid", "re");
48 if (!f)
49 return (0);
50
51 if (fscanf(f, "%lx", &hostid) != 1)
52 hostid = 0;
53
54 fclose(f);
55
56 return (hostid);
57 }
58
59 unsigned long
get_system_hostid(void)60 get_system_hostid(void)
61 {
62 unsigned long hostid = get_spl_hostid();
63 uint32_t system_hostid;
64
65 /*
66 * We do not use gethostid(3) because it can return a bogus ID,
67 * depending on the libc and /etc/hostid presence,
68 * and the kernel and userspace must agree.
69 * See comments above hostid_read() in the SPL.
70 */
71 if (hostid == 0) {
72 int fd = open("/etc/hostid", O_RDONLY | O_CLOEXEC);
73 if (fd >= 0) {
74 if (read(fd, &system_hostid, sizeof (system_hostid))
75 != sizeof (system_hostid))
76 hostid = 0;
77 else
78 hostid = system_hostid;
79 (void) close(fd);
80 }
81 }
82
83 return (hostid & HOSTID_MASK);
84 }
85