1 /* Copyright (C) 2005-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18 #include <errno.h>
19 #include <getopt.h>
20 #include <stdbool.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/wait.h>
25 #include <stackguard-macros.h>
26 #include <tls.h>
27 #include <unistd.h>
28
29 static const char *command;
30 static bool child;
31 static uintptr_t stack_chk_guard_copy;
32 static bool stack_chk_guard_copy_set;
33 static int fds[2];
34
35 static void __attribute__ ((constructor))
con(void)36 con (void)
37 {
38 stack_chk_guard_copy = STACK_CHK_GUARD;
39 stack_chk_guard_copy_set = true;
40 }
41
42 static int
uintptr_t_cmp(const void * a,const void * b)43 uintptr_t_cmp (const void *a, const void *b)
44 {
45 if (*(uintptr_t *) a < *(uintptr_t *) b)
46 return 1;
47 if (*(uintptr_t *) a > *(uintptr_t *) b)
48 return -1;
49 return 0;
50 }
51
52 static int
do_test(void)53 do_test (void)
54 {
55 if (!stack_chk_guard_copy_set)
56 {
57 puts ("constructor has not been run");
58 return 1;
59 }
60
61 if (stack_chk_guard_copy != STACK_CHK_GUARD)
62 {
63 puts ("STACK_CHK_GUARD changed between constructor and do_test");
64 return 1;
65 }
66
67 if (child)
68 {
69 write (2, &stack_chk_guard_copy, sizeof (stack_chk_guard_copy));
70 return 0;
71 }
72
73 if (command == NULL)
74 {
75 puts ("missing --command or --child argument");
76 return 1;
77 }
78
79 #define N 16
80 uintptr_t child_stack_chk_guards[N + 1];
81 child_stack_chk_guards[N] = stack_chk_guard_copy;
82 int i;
83 for (i = 0; i < N; ++i)
84 {
85 if (pipe (fds) < 0)
86 {
87 printf ("couldn't create pipe: %m\n");
88 return 1;
89 }
90
91 pid_t pid = fork ();
92 if (pid < 0)
93 {
94 printf ("fork failed: %m\n");
95 return 1;
96 }
97
98 if (!pid)
99 {
100 if (stack_chk_guard_copy != STACK_CHK_GUARD)
101 {
102 puts ("STACK_CHK_GUARD changed after fork");
103 exit (1);
104 }
105
106 close (fds[0]);
107 close (2);
108 dup2 (fds[1], 2);
109 close (fds[1]);
110
111 system (command);
112 exit (0);
113 }
114
115 close (fds[1]);
116
117 if (TEMP_FAILURE_RETRY (read (fds[0], &child_stack_chk_guards[i],
118 sizeof (uintptr_t))) != sizeof (uintptr_t))
119 {
120 puts ("could not read stack_chk_guard value from child");
121 return 1;
122 }
123
124 close (fds[0]);
125
126 pid_t termpid;
127 int status;
128 termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
129 if (termpid == -1)
130 {
131 printf ("waitpid failed: %m\n");
132 return 1;
133 }
134 else if (termpid != pid)
135 {
136 printf ("waitpid returned %ld != %ld\n",
137 (long int) termpid, (long int) pid);
138 return 1;
139 }
140 else if (!WIFEXITED (status) || WEXITSTATUS (status))
141 {
142 puts ("child hasn't exited with exit status 0");
143 return 1;
144 }
145 }
146
147 qsort (child_stack_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp);
148
149 uintptr_t default_guard = 0;
150 unsigned char *p = (unsigned char *) &default_guard;
151 p[sizeof (uintptr_t) - 1] = 255;
152 p[sizeof (uintptr_t) - 2] = '\n';
153 p[0] = 0;
154
155 /* Test if the stack guard canaries are either randomized,
156 or equal to the default stack guard canary value.
157 Even with randomized stack guards it might happen
158 that the random number generator generates the same
159 values, but if that happens in more than half from
160 the 16 runs, something is very wrong. */
161 int ndifferences = 0;
162 int ndefaults = 0;
163 for (i = 0; i < N; ++i)
164 {
165 if (child_stack_chk_guards[i] != child_stack_chk_guards[i+1])
166 ndifferences++;
167 else if (child_stack_chk_guards[i] == default_guard)
168 ndefaults++;
169 }
170
171 printf ("differences %d defaults %d\n", ndifferences, ndefaults);
172
173 if (ndifferences < N / 2 && ndefaults < N / 2)
174 {
175 puts ("stack guard canaries are not randomized enough");
176 puts ("nor equal to the default canary value");
177 return 1;
178 }
179
180 return 0;
181 }
182
183 #define OPT_COMMAND 10000
184 #define OPT_CHILD 10001
185 #define CMDLINE_OPTIONS \
186 { "command", required_argument, NULL, OPT_COMMAND }, \
187 { "child", no_argument, NULL, OPT_CHILD },
188
189 static void __attribute__((used))
cmdline_process_function(int c)190 cmdline_process_function (int c)
191 {
192 switch (c)
193 {
194 case OPT_COMMAND:
195 command = optarg;
196 break;
197 case OPT_CHILD:
198 child = true;
199 break;
200 }
201 }
202 #define CMDLINE_PROCESS cmdline_process_function
203
204 #include <support/test-driver.c>
205