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1 | /* Test that subprocesses generate distinct streams of randomness. |
2 | Copyright (C) 2022 Free Software Foundation, Inc. | |
3 | This file is part of the GNU C Library. | |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
17 | <https://www.gnu.org/licenses/>. */ | |
18 | ||
19 | /* Collect random data from subprocesses and check that all the | |
20 | results are unique. */ | |
21 | ||
22 | #include <array_length.h> | |
23 | #include <stdlib.h> | |
24 | #include <stdio.h> | |
25 | #include <string.h> | |
26 | #include <support/check.h> | |
27 | #include <support/support.h> | |
28 | #include <support/xthread.h> | |
29 | #include <support/xunistd.h> | |
30 | #include <unistd.h> | |
31 | ||
32 | /* Perform multiple runs. The subsequent runs start with an | |
33 | already-initialized random number generator. (The number 1500 was | |
34 | seen to reproduce failures reliable in case of a race condition in | |
35 | the fork detection code.) */ | |
36 | enum { runs = 1500 }; | |
37 | ||
38 | /* One hundred processes in total. This should be high enough to | |
39 | expose any issues, but low enough not to tax the overall system too | |
40 | much. */ | |
41 | enum { subprocesses = 49 }; | |
42 | ||
43 | /* The total number of processes. */ | |
44 | enum { processes = subprocesses + 1 }; | |
45 | ||
46 | /* Number of bytes of randomness to generate per process. Large | |
47 | enough to make false positive duplicates extremely unlikely. */ | |
48 | enum { random_size = 16 }; | |
49 | ||
50 | /* Generated bytes of randomness. */ | |
51 | struct result | |
52 | { | |
53 | unsigned char bytes[random_size]; | |
54 | }; | |
55 | ||
56 | /* Shared across all processes. */ | |
57 | static struct shared_data | |
58 | { | |
59 | pthread_barrier_t barrier; | |
60 | struct result results[runs][processes]; | |
61 | } *shared_data; | |
62 | ||
63 | static void | |
64 | generate_arc4random (unsigned char *bytes) | |
65 | { | |
66 | for (int i = 0; i < random_size / sizeof (uint32_t); i++) | |
67 | { | |
68 | uint32_t x = arc4random (); | |
69 | memcpy (&bytes[4 * i], &x, sizeof x); | |
70 | } | |
71 | } | |
72 | ||
73 | static void | |
74 | generate_arc4random_buf (unsigned char *bytes) | |
75 | { | |
76 | arc4random_buf (bytes, random_size); | |
77 | } | |
78 | ||
79 | static void | |
80 | generate_arc4random_uniform (unsigned char *bytes) | |
81 | { | |
82 | for (int i = 0; i < random_size; i++) | |
83 | bytes[i] = arc4random_uniform (256); | |
84 | } | |
85 | ||
86 | /* Invoked to collect data from a subprocess. */ | |
87 | static void | |
88 | subprocess (int run, int process_index, void (*func)(unsigned char *)) | |
89 | { | |
90 | xpthread_barrier_wait (&shared_data->barrier); | |
91 | func (shared_data->results[run][process_index].bytes); | |
92 | } | |
93 | ||
94 | /* Used to sort the results. */ | |
95 | struct index | |
96 | { | |
97 | int run; | |
98 | int process_index; | |
99 | }; | |
100 | ||
101 | /* Used to sort an array of struct index values. */ | |
102 | static int | |
103 | index_compare (const void *left1, const void *right1) | |
104 | { | |
105 | const struct index *left = left1; | |
106 | const struct index *right = right1; | |
107 | ||
108 | return memcmp (shared_data->results[left->run][left->process_index].bytes, | |
109 | shared_data->results[right->run][right->process_index].bytes, | |
110 | random_size); | |
111 | } | |
112 | ||
113 | static int | |
114 | do_test_func (void (*func)(unsigned char *bytes)) | |
115 | { | |
116 | /* Collect random data. */ | |
117 | for (int run = 0; run < runs; ++run) | |
118 | { | |
119 | pid_t pids[subprocesses]; | |
120 | for (int process_index = 0; process_index < subprocesses; | |
121 | ++process_index) | |
122 | { | |
123 | pids[process_index] = xfork (); | |
124 | if (pids[process_index] == 0) | |
125 | { | |
126 | subprocess (run, process_index, func); | |
127 | _exit (0); | |
128 | } | |
129 | } | |
130 | ||
131 | /* Trigger all subprocesses. Also add data from the parent | |
132 | process. */ | |
133 | subprocess (run, subprocesses, func); | |
134 | ||
135 | for (int process_index = 0; process_index < subprocesses; | |
136 | ++process_index) | |
137 | { | |
138 | int status; | |
139 | xwaitpid (pids[process_index], &status, 0); | |
140 | if (status != 0) | |
141 | FAIL_EXIT1 ("subprocess index %d (PID %d) exit status %d\n", | |
142 | process_index, (int) pids[process_index], status); | |
143 | } | |
144 | } | |
145 | ||
146 | /* Check for duplicates. */ | |
147 | struct index indexes[runs * processes]; | |
148 | for (int run = 0; run < runs; ++run) | |
149 | for (int process_index = 0; process_index < processes; ++process_index) | |
150 | indexes[run * processes + process_index] | |
151 | = (struct index) { .run = run, .process_index = process_index }; | |
152 | qsort (indexes, array_length (indexes), sizeof (indexes[0]), index_compare); | |
153 | for (size_t i = 1; i < array_length (indexes); ++i) | |
154 | { | |
155 | if (index_compare (indexes + i - 1, indexes + i) == 0) | |
156 | { | |
157 | support_record_failure (); | |
158 | unsigned char *bytes | |
159 | = shared_data->results[indexes[i].run] | |
160 | [indexes[i].process_index].bytes; | |
161 | char *quoted = support_quote_blob (bytes, random_size); | |
162 | printf ("error: duplicate randomness data: \"%s\"\n" | |
163 | " run %d, subprocess %d\n" | |
164 | " run %d, subprocess %d\n", | |
165 | quoted, indexes[i - 1].run, indexes[i - 1].process_index, | |
166 | indexes[i].run, indexes[i].process_index); | |
167 | free (quoted); | |
168 | } | |
169 | } | |
170 | ||
171 | return 0; | |
172 | } | |
173 | ||
174 | static int | |
175 | do_test (void) | |
176 | { | |
177 | shared_data = support_shared_allocate (sizeof (*shared_data)); | |
178 | { | |
179 | pthread_barrierattr_t attr; | |
180 | xpthread_barrierattr_init (&attr); | |
181 | xpthread_barrierattr_setpshared (&attr, PTHREAD_PROCESS_SHARED); | |
182 | xpthread_barrier_init (&shared_data->barrier, &attr, processes); | |
183 | xpthread_barrierattr_destroy (&attr); | |
184 | } | |
185 | ||
186 | do_test_func (generate_arc4random); | |
187 | do_test_func (generate_arc4random_buf); | |
188 | do_test_func (generate_arc4random_uniform); | |
189 | ||
190 | xpthread_barrier_destroy (&shared_data->barrier); | |
191 | support_shared_free (shared_data); | |
192 | shared_data = NULL; | |
193 | ||
194 | return 0; | |
195 | } | |
196 | ||
197 | #define TIMEOUT 40 | |
198 | #include <support/test-driver.c> |