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d7ccca2e LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <unistd.h> | |
23 | #include <stdio.h> | |
24 | #include <errno.h> | |
25 | #include <string.h> | |
26 | #include <stdlib.h> | |
27 | #include <fcntl.h> | |
28 | #include <sys/mount.h> | |
29 | ||
81527be1 LP |
30 | #include <systemd/sd-id128.h> |
31 | ||
d7ccca2e LP |
32 | #include "machine-id-setup.h" |
33 | #include "macro.h" | |
34 | #include "util.h" | |
35 | #include "log.h" | |
8d41a963 | 36 | |
d7ccca2e | 37 | static int generate(char id[34]) { |
87d2c1ff LP |
38 | int fd, r; |
39 | unsigned char *p; | |
40 | sd_id128_t buf; | |
8d41a963 | 41 | char *q; |
d7ccca2e LP |
42 | ssize_t k; |
43 | ||
44 | assert(id); | |
45 | ||
46 | /* First, try reading the D-Bus machine id, unless it is a symlink */ | |
8d41a963 LP |
47 | fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); |
48 | if (fd >= 0) { | |
d7ccca2e LP |
49 | |
50 | k = loop_read(fd, id, 33, false); | |
51 | close_nointr_nofail(fd); | |
52 | ||
53 | if (k >= 32) { | |
54 | id[32] = '\n'; | |
55 | id[33] = 0; | |
56 | ||
57 | log_info("Initializing machine ID from D-Bus machine ID."); | |
58 | return 0; | |
59 | } | |
60 | } | |
61 | ||
62 | /* If that didn't work, generate a random machine id */ | |
87d2c1ff LP |
63 | r = sd_id128_randomize(&buf); |
64 | if (r < 0) { | |
65 | log_error("Failed to open /dev/urandom: %s", strerror(-r)); | |
66 | return r; | |
d7ccca2e LP |
67 | } |
68 | ||
87d2c1ff | 69 | for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) { |
d7ccca2e LP |
70 | q[0] = hexchar(*p >> 4); |
71 | q[1] = hexchar(*p & 15); | |
72 | } | |
73 | ||
74 | id[32] = '\n'; | |
75 | id[33] = 0; | |
76 | ||
77 | log_info("Initializing machine ID from random generator."); | |
78 | ||
79 | return 0; | |
80 | } | |
81 | ||
82 | int machine_id_setup(void) { | |
83 | int fd, r; | |
84 | bool writable; | |
85 | struct stat st; | |
86 | char id[34]; /* 32 + \n + \0 */ | |
87 | mode_t m; | |
88 | ||
89 | m = umask(0000); | |
90 | ||
76526bad LP |
91 | /* We create this 0444, to indicate that this isn't really |
92 | * something you should ever modify. Of course, since the file | |
93 | * will be owned by root it doesn't matter much, but maybe | |
94 | * people look. */ | |
95 | ||
8d41a963 LP |
96 | fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); |
97 | if (fd >= 0) | |
d7ccca2e LP |
98 | writable = true; |
99 | else { | |
8d41a963 LP |
100 | fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY); |
101 | if (fd < 0) { | |
d7ccca2e LP |
102 | umask(m); |
103 | log_error("Cannot open /etc/machine-id: %m"); | |
104 | return -errno; | |
105 | } | |
106 | ||
107 | writable = false; | |
108 | } | |
109 | ||
110 | umask(m); | |
111 | ||
112 | if (fstat(fd, &st) < 0) { | |
113 | log_error("fstat() failed: %m"); | |
114 | r = -errno; | |
115 | goto finish; | |
116 | } | |
117 | ||
118 | if (S_ISREG(st.st_mode)) { | |
119 | if (loop_read(fd, id, 32, false) >= 32) { | |
120 | r = 0; | |
121 | goto finish; | |
122 | } | |
123 | } | |
124 | ||
125 | /* Hmm, so, the id currently stored is not useful, then let's | |
126 | * generate one */ | |
127 | ||
8d41a963 LP |
128 | r = generate(id); |
129 | if (r < 0) | |
d7ccca2e LP |
130 | goto finish; |
131 | ||
132 | if (S_ISREG(st.st_mode) && writable) { | |
133 | lseek(fd, 0, SEEK_SET); | |
134 | ||
135 | if (loop_write(fd, id, 33, false) == 33) { | |
136 | r = 0; | |
137 | goto finish; | |
138 | } | |
139 | } | |
140 | ||
141 | close_nointr_nofail(fd); | |
142 | fd = -1; | |
143 | ||
144 | /* Hmm, we couldn't write it? So let's write it to | |
2b583ce6 | 145 | * /run/systemd/machine-id as a replacement */ |
d7ccca2e | 146 | |
2b583ce6 | 147 | mkdir_p("/run/systemd", 0755); |
d7ccca2e | 148 | |
4c12626c | 149 | m = umask(0022); |
8d41a963 | 150 | r = write_one_line_file("/run/systemd/machine-id", id); |
4c12626c LP |
151 | umask(m); |
152 | ||
8d41a963 | 153 | if (r < 0) { |
2b583ce6 | 154 | log_error("Cannot write /run/systemd/machine-id: %s", strerror(-r)); |
d7ccca2e | 155 | |
2b583ce6 | 156 | unlink("/run/systemd/machine-id"); |
d7ccca2e LP |
157 | goto finish; |
158 | } | |
159 | ||
160 | /* And now, let's mount it over */ | |
2b583ce6 KS |
161 | r = mount("/run/systemd/machine-id", "/etc/machine-id", "bind", MS_BIND|MS_RDONLY, NULL) < 0 ? -errno : 0; |
162 | unlink("/run/systemd/machine-id"); | |
d7ccca2e LP |
163 | |
164 | if (r < 0) | |
165 | log_error("Failed to mount /etc/machine-id: %s", strerror(-r)); | |
166 | else | |
9b4f818b | 167 | log_info("Installed transient /etc/machine-id file."); |
d7ccca2e LP |
168 | |
169 | finish: | |
170 | ||
171 | if (fd >= 0) | |
172 | close_nointr_nofail(fd); | |
173 | ||
174 | return r; | |
175 | } |