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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 | ||
30 | #include "machine-id-setup.h" | |
31 | #include "macro.h" | |
32 | #include "util.h" | |
33 | #include "log.h" | |
87d2c1ff | 34 | #include "sd-id128.h" |
8d41a963 | 35 | |
d7ccca2e | 36 | static int generate(char id[34]) { |
87d2c1ff LP |
37 | int fd, r; |
38 | unsigned char *p; | |
39 | sd_id128_t buf; | |
8d41a963 | 40 | char *q; |
d7ccca2e LP |
41 | ssize_t k; |
42 | ||
43 | assert(id); | |
44 | ||
45 | /* First, try reading the D-Bus machine id, unless it is a symlink */ | |
8d41a963 LP |
46 | fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); |
47 | if (fd >= 0) { | |
d7ccca2e LP |
48 | |
49 | k = loop_read(fd, id, 33, false); | |
50 | close_nointr_nofail(fd); | |
51 | ||
52 | if (k >= 32) { | |
53 | id[32] = '\n'; | |
54 | id[33] = 0; | |
55 | ||
56 | log_info("Initializing machine ID from D-Bus machine ID."); | |
57 | return 0; | |
58 | } | |
59 | } | |
60 | ||
61 | /* If that didn't work, generate a random machine id */ | |
87d2c1ff LP |
62 | r = sd_id128_randomize(&buf); |
63 | if (r < 0) { | |
64 | log_error("Failed to open /dev/urandom: %s", strerror(-r)); | |
65 | return r; | |
d7ccca2e LP |
66 | } |
67 | ||
87d2c1ff | 68 | for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) { |
d7ccca2e LP |
69 | q[0] = hexchar(*p >> 4); |
70 | q[1] = hexchar(*p & 15); | |
71 | } | |
72 | ||
73 | id[32] = '\n'; | |
74 | id[33] = 0; | |
75 | ||
76 | log_info("Initializing machine ID from random generator."); | |
77 | ||
78 | return 0; | |
79 | } | |
80 | ||
81 | int machine_id_setup(void) { | |
82 | int fd, r; | |
83 | bool writable; | |
84 | struct stat st; | |
85 | char id[34]; /* 32 + \n + \0 */ | |
86 | mode_t m; | |
87 | ||
88 | m = umask(0000); | |
89 | ||
76526bad LP |
90 | /* We create this 0444, to indicate that this isn't really |
91 | * something you should ever modify. Of course, since the file | |
92 | * will be owned by root it doesn't matter much, but maybe | |
93 | * people look. */ | |
94 | ||
8d41a963 LP |
95 | fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); |
96 | if (fd >= 0) | |
d7ccca2e LP |
97 | writable = true; |
98 | else { | |
8d41a963 LP |
99 | fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY); |
100 | if (fd < 0) { | |
d7ccca2e LP |
101 | umask(m); |
102 | log_error("Cannot open /etc/machine-id: %m"); | |
103 | return -errno; | |
104 | } | |
105 | ||
106 | writable = false; | |
107 | } | |
108 | ||
109 | umask(m); | |
110 | ||
111 | if (fstat(fd, &st) < 0) { | |
112 | log_error("fstat() failed: %m"); | |
113 | r = -errno; | |
114 | goto finish; | |
115 | } | |
116 | ||
117 | if (S_ISREG(st.st_mode)) { | |
118 | if (loop_read(fd, id, 32, false) >= 32) { | |
119 | r = 0; | |
120 | goto finish; | |
121 | } | |
122 | } | |
123 | ||
124 | /* Hmm, so, the id currently stored is not useful, then let's | |
125 | * generate one */ | |
126 | ||
8d41a963 LP |
127 | r = generate(id); |
128 | if (r < 0) | |
d7ccca2e LP |
129 | goto finish; |
130 | ||
131 | if (S_ISREG(st.st_mode) && writable) { | |
132 | lseek(fd, 0, SEEK_SET); | |
133 | ||
134 | if (loop_write(fd, id, 33, false) == 33) { | |
135 | r = 0; | |
136 | goto finish; | |
137 | } | |
138 | } | |
139 | ||
140 | close_nointr_nofail(fd); | |
141 | fd = -1; | |
142 | ||
143 | /* Hmm, we couldn't write it? So let's write it to | |
2b583ce6 | 144 | * /run/systemd/machine-id as a replacement */ |
d7ccca2e | 145 | |
2b583ce6 | 146 | mkdir_p("/run/systemd", 0755); |
d7ccca2e | 147 | |
4c12626c | 148 | m = umask(0022); |
8d41a963 | 149 | r = write_one_line_file("/run/systemd/machine-id", id); |
4c12626c LP |
150 | umask(m); |
151 | ||
8d41a963 | 152 | if (r < 0) { |
2b583ce6 | 153 | log_error("Cannot write /run/systemd/machine-id: %s", strerror(-r)); |
d7ccca2e | 154 | |
2b583ce6 | 155 | unlink("/run/systemd/machine-id"); |
d7ccca2e LP |
156 | goto finish; |
157 | } | |
158 | ||
159 | /* And now, let's mount it over */ | |
2b583ce6 KS |
160 | r = mount("/run/systemd/machine-id", "/etc/machine-id", "bind", MS_BIND|MS_RDONLY, NULL) < 0 ? -errno : 0; |
161 | unlink("/run/systemd/machine-id"); | |
d7ccca2e LP |
162 | |
163 | if (r < 0) | |
164 | log_error("Failed to mount /etc/machine-id: %s", strerror(-r)); | |
165 | else | |
9b4f818b | 166 | log_info("Installed transient /etc/machine-id file."); |
d7ccca2e LP |
167 | |
168 | finish: | |
169 | ||
170 | if (fd >= 0) | |
171 | close_nointr_nofail(fd); | |
172 | ||
173 | return r; | |
174 | } |