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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" | |
34 | ||
35 | static int generate(char id[34]) { | |
36 | int fd; | |
37 | char buf[16]; | |
38 | char *p, *q; | |
39 | ssize_t k; | |
40 | ||
41 | assert(id); | |
42 | ||
43 | /* First, try reading the D-Bus machine id, unless it is a symlink */ | |
44 | if ((fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW)) >= 0) { | |
45 | ||
46 | k = loop_read(fd, id, 33, false); | |
47 | close_nointr_nofail(fd); | |
48 | ||
49 | if (k >= 32) { | |
50 | id[32] = '\n'; | |
51 | id[33] = 0; | |
52 | ||
53 | log_info("Initializing machine ID from D-Bus machine ID."); | |
54 | return 0; | |
55 | } | |
56 | } | |
57 | ||
58 | /* If that didn't work, generate a random machine id */ | |
59 | if ((fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) { | |
60 | log_error("Failed to open /dev/urandom: %m"); | |
61 | return -errno; | |
62 | } | |
63 | ||
64 | k = loop_read(fd, buf, sizeof(buf), false); | |
65 | close_nointr_nofail(fd); | |
66 | ||
67 | if (k != sizeof(buf)) { | |
68 | log_error("Failed to read /dev/urandom: %s", strerror(k < 0 ? -k : EIO)); | |
69 | return k < 0 ? (int) k : -EIO; | |
70 | } | |
71 | ||
72 | for (p = buf, q = id; p < buf + sizeof(buf); p++, q += 2) { | |
73 | q[0] = hexchar(*p >> 4); | |
74 | q[1] = hexchar(*p & 15); | |
75 | } | |
76 | ||
77 | id[32] = '\n'; | |
78 | id[33] = 0; | |
79 | ||
80 | log_info("Initializing machine ID from random generator."); | |
81 | ||
82 | return 0; | |
83 | } | |
84 | ||
85 | int machine_id_setup(void) { | |
86 | int fd, r; | |
87 | bool writable; | |
88 | struct stat st; | |
89 | char id[34]; /* 32 + \n + \0 */ | |
90 | mode_t m; | |
91 | ||
92 | m = umask(0000); | |
93 | ||
76526bad LP |
94 | /* We create this 0444, to indicate that this isn't really |
95 | * something you should ever modify. Of course, since the file | |
96 | * will be owned by root it doesn't matter much, but maybe | |
97 | * people look. */ | |
98 | ||
99 | if ((fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444)) >= 0) | |
d7ccca2e LP |
100 | writable = true; |
101 | else { | |
102 | if ((fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) { | |
103 | umask(m); | |
104 | log_error("Cannot open /etc/machine-id: %m"); | |
105 | return -errno; | |
106 | } | |
107 | ||
108 | writable = false; | |
109 | } | |
110 | ||
111 | umask(m); | |
112 | ||
113 | if (fstat(fd, &st) < 0) { | |
114 | log_error("fstat() failed: %m"); | |
115 | r = -errno; | |
116 | goto finish; | |
117 | } | |
118 | ||
119 | if (S_ISREG(st.st_mode)) { | |
120 | if (loop_read(fd, id, 32, false) >= 32) { | |
121 | r = 0; | |
122 | goto finish; | |
123 | } | |
124 | } | |
125 | ||
126 | /* Hmm, so, the id currently stored is not useful, then let's | |
127 | * generate one */ | |
128 | ||
129 | if ((r = generate(id)) < 0) | |
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 | |
b925e726 | 145 | * /dev/.run/systemd/machine-id as a replacement */ |
d7ccca2e | 146 | |
b925e726 | 147 | mkdir_p("/dev/.run/systemd", 0755); |
d7ccca2e | 148 | |
b925e726 LP |
149 | if ((r = write_one_line_file("/dev/.run/systemd/machine-id", id)) < 0) { |
150 | log_error("Cannot write /dev/.run/systemd/machine-id: %s", strerror(-r)); | |
d7ccca2e | 151 | |
b925e726 | 152 | unlink("/dev/.run/systemd/machine-id"); |
d7ccca2e LP |
153 | goto finish; |
154 | } | |
155 | ||
156 | /* And now, let's mount it over */ | |
b925e726 LP |
157 | r = mount("/dev/.run/systemd/machine-id", "/etc/machine-id", "bind", MS_BIND|MS_RDONLY, NULL) < 0 ? -errno : 0; |
158 | unlink("/dev/.run/systemd/machine-id"); | |
d7ccca2e LP |
159 | |
160 | if (r < 0) | |
161 | log_error("Failed to mount /etc/machine-id: %s", strerror(-r)); | |
162 | else | |
9b4f818b | 163 | log_info("Installed transient /etc/machine-id file."); |
d7ccca2e LP |
164 | |
165 | finish: | |
166 | ||
167 | if (fd >= 0) | |
168 | close_nointr_nofail(fd); | |
169 | ||
170 | return r; | |
171 | } |