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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 <fcntl.h> | |
24 | #include <errno.h> | |
25 | #include <string.h> | |
26 | #include <sys/stat.h> | |
27 | ||
28 | #include "log.h" | |
29 | #include "util.h" | |
30 | ||
31 | int main(int argc, char *argv[]) { | |
32 | int seed_fd = -1, random_fd = -1; | |
33 | int ret = 1; | |
34 | uint8_t buf[512]; | |
35 | ssize_t r; | |
36 | ||
37 | if (argc != 2) { | |
38 | log_error("This program requires one argument."); | |
39 | return 1; | |
40 | } | |
41 | ||
42 | log_set_target(LOG_TARGET_SYSLOG_OR_KMSG); | |
43 | log_parse_environment(); | |
44 | log_open(); | |
45 | ||
46 | /* When we load the seed we read it and write it to the device | |
47 | * and then immediately update the saved seed with new data, | |
48 | * to make sure the next boot gets seeded differently. */ | |
49 | ||
50 | if (streq(argv[1], "load")) { | |
51 | ||
52 | if ((seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) { | |
53 | if ((seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) { | |
54 | log_error("Failed to open random seed: %m"); | |
55 | goto finish; | |
56 | } | |
57 | } | |
58 | ||
59 | if ((random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600)) < 0) { | |
60 | if ((random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600)) < 0) { | |
61 | log_error("Failed to open /dev/urandom: %m"); | |
62 | goto finish; | |
63 | } | |
64 | } | |
65 | ||
66 | if ((r = loop_read(seed_fd, buf, sizeof(buf), false)) != sizeof(buf)) | |
67 | log_error("Failed to read seed file: %s", r < 0 ? strerror(errno) : "EOF"); | |
68 | else { | |
69 | lseek(seed_fd, 0, SEEK_SET); | |
70 | ||
71 | if ((r = loop_write(random_fd, buf, sizeof(buf), false)) != sizeof(buf)) | |
72 | log_error("Failed to write seed to /dev/random: %s", r < 0 ? strerror(errno) : "short write"); | |
73 | } | |
74 | ||
75 | } else if (streq(argv[1], "save")) { | |
76 | ||
77 | if ((seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600)) < 0) { | |
78 | log_error("Failed to open random seed: %m"); | |
79 | goto finish; | |
80 | } | |
81 | ||
82 | if ((random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) { | |
83 | log_error("Failed to open /dev/urandom: %m"); | |
84 | goto finish; | |
85 | } | |
86 | } else { | |
87 | log_error("Unknown verb %s.", argv[1]); | |
88 | goto finish; | |
89 | } | |
90 | ||
91 | /* This is just a safety measure. Given that we are root and | |
92 | * most likely created the file ourselves the mode and owner | |
93 | * should be correct anyway. */ | |
94 | fchmod(seed_fd, 0600); | |
95 | fchown(seed_fd, 0, 0); | |
96 | ||
97 | if ((r = loop_read(random_fd, buf, sizeof(buf), false)) != sizeof(buf)) | |
98 | log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(errno) : "EOF"); | |
99 | else { | |
100 | if ((r = loop_write(seed_fd, buf, sizeof(buf), false)) != sizeof(buf)) | |
101 | log_error("Failed to write new random seed file: %s", r < 0 ? strerror(errno) : "short write"); | |
102 | } | |
103 | ||
104 | ret = 0; | |
105 | ||
106 | finish: | |
107 | if (random_fd >= 0) | |
108 | close_nointr_nofail(random_fd); | |
109 | ||
110 | if (seed_fd >= 0) | |
111 | close_nointr_nofail(seed_fd); | |
112 | ||
113 | return ret; | |
114 | } |