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1 | /* SPDX-License-Identifier: LGPL-2.1+ */ | |
2 | /*** | |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2010 Lennart Poettering | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
21 | #include <errno.h> | |
22 | #include <fcntl.h> | |
23 | #include <string.h> | |
24 | #include <sys/stat.h> | |
25 | #include <unistd.h> | |
26 | ||
27 | #include "alloc-util.h" | |
28 | #include "fd-util.h" | |
29 | #include "io-util.h" | |
30 | #include "log.h" | |
31 | #include "mkdir.h" | |
32 | #include "string-util.h" | |
33 | #include "util.h" | |
34 | ||
35 | #define POOL_SIZE_MIN 512 | |
36 | ||
37 | int main(int argc, char *argv[]) { | |
38 | _cleanup_close_ int seed_fd = -1, random_fd = -1; | |
39 | _cleanup_free_ void* buf = NULL; | |
40 | size_t buf_size = 0; | |
41 | ssize_t k; | |
42 | int r, open_rw_error; | |
43 | FILE *f; | |
44 | bool refresh_seed_file = true; | |
45 | ||
46 | if (argc != 2) { | |
47 | log_error("This program requires one argument."); | |
48 | return EXIT_FAILURE; | |
49 | } | |
50 | ||
51 | log_set_target(LOG_TARGET_AUTO); | |
52 | log_parse_environment(); | |
53 | log_open(); | |
54 | ||
55 | umask(0022); | |
56 | ||
57 | /* Read pool size, if possible */ | |
58 | f = fopen("/proc/sys/kernel/random/poolsize", "re"); | |
59 | if (f) { | |
60 | if (fscanf(f, "%zu", &buf_size) > 0) | |
61 | /* poolsize is in bits on 2.6, but we want bytes */ | |
62 | buf_size /= 8; | |
63 | ||
64 | fclose(f); | |
65 | } | |
66 | ||
67 | if (buf_size <= POOL_SIZE_MIN) | |
68 | buf_size = POOL_SIZE_MIN; | |
69 | ||
70 | buf = malloc(buf_size); | |
71 | if (!buf) { | |
72 | r = log_oom(); | |
73 | goto finish; | |
74 | } | |
75 | ||
76 | r = mkdir_parents_label(RANDOM_SEED, 0755); | |
77 | if (r < 0) { | |
78 | log_error_errno(r, "Failed to create directory " RANDOM_SEED_DIR ": %m"); | |
79 | goto finish; | |
80 | } | |
81 | ||
82 | /* When we load the seed we read it and write it to the device | |
83 | * and then immediately update the saved seed with new data, | |
84 | * to make sure the next boot gets seeded differently. */ | |
85 | ||
86 | if (streq(argv[1], "load")) { | |
87 | ||
88 | seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600); | |
89 | open_rw_error = -errno; | |
90 | if (seed_fd < 0) { | |
91 | refresh_seed_file = false; | |
92 | ||
93 | seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY); | |
94 | if (seed_fd < 0) { | |
95 | bool missing = errno == ENOENT; | |
96 | ||
97 | log_full_errno(missing ? LOG_DEBUG : LOG_ERR, | |
98 | open_rw_error, "Failed to open " RANDOM_SEED " for writing: %m"); | |
99 | r = log_full_errno(missing ? LOG_DEBUG : LOG_ERR, | |
100 | errno, "Failed to open " RANDOM_SEED " for reading: %m"); | |
101 | if (missing) | |
102 | r = 0; | |
103 | ||
104 | goto finish; | |
105 | } | |
106 | } | |
107 | ||
108 | random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600); | |
109 | if (random_fd < 0) { | |
110 | random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600); | |
111 | if (random_fd < 0) { | |
112 | r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); | |
113 | goto finish; | |
114 | } | |
115 | } | |
116 | ||
117 | k = loop_read(seed_fd, buf, buf_size, false); | |
118 | if (k < 0) | |
119 | r = log_error_errno(k, "Failed to read seed from " RANDOM_SEED ": %m"); | |
120 | else if (k == 0) { | |
121 | r = 0; | |
122 | log_debug("Seed file " RANDOM_SEED " not yet initialized, proceeding."); | |
123 | } else { | |
124 | (void) lseek(seed_fd, 0, SEEK_SET); | |
125 | ||
126 | r = loop_write(random_fd, buf, (size_t) k, false); | |
127 | if (r < 0) | |
128 | log_error_errno(r, "Failed to write seed to /dev/urandom: %m"); | |
129 | } | |
130 | ||
131 | } else if (streq(argv[1], "save")) { | |
132 | ||
133 | seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600); | |
134 | if (seed_fd < 0) { | |
135 | r = log_error_errno(errno, "Failed to open " RANDOM_SEED ": %m"); | |
136 | goto finish; | |
137 | } | |
138 | ||
139 | random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY); | |
140 | if (random_fd < 0) { | |
141 | r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); | |
142 | goto finish; | |
143 | } | |
144 | ||
145 | } else { | |
146 | log_error("Unknown verb '%s'.", argv[1]); | |
147 | r = -EINVAL; | |
148 | goto finish; | |
149 | } | |
150 | ||
151 | if (refresh_seed_file) { | |
152 | ||
153 | /* This is just a safety measure. Given that we are root and | |
154 | * most likely created the file ourselves the mode and owner | |
155 | * should be correct anyway. */ | |
156 | (void) fchmod(seed_fd, 0600); | |
157 | (void) fchown(seed_fd, 0, 0); | |
158 | ||
159 | k = loop_read(random_fd, buf, buf_size, false); | |
160 | if (k < 0) { | |
161 | r = log_error_errno(k, "Failed to read new seed from /dev/urandom: %m"); | |
162 | goto finish; | |
163 | } | |
164 | if (k == 0) { | |
165 | log_error("Got EOF while reading from /dev/urandom."); | |
166 | r = -EIO; | |
167 | goto finish; | |
168 | } | |
169 | ||
170 | r = loop_write(seed_fd, buf, (size_t) k, false); | |
171 | if (r < 0) | |
172 | log_error_errno(r, "Failed to write new random seed file: %m"); | |
173 | } | |
174 | ||
175 | finish: | |
176 | return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; | |
177 | } |