1 /* Test program for making nonexecutable stacks executable
2 on load of a DSO that requires executable stacks. */
16 asprintf (&cmd, "cat /proc/%d/maps", getpid ());
22 static void deeper (void (*f) (void));
28 tryme_thread (void *f)
30 (*((void (*) (void)) f)) ();
35 static pthread_barrier_t startup_barrier, go_barrier;
37 waiter_thread (void *arg)
40 pthread_barrier_wait (&startup_barrier);
41 pthread_barrier_wait (&go_barrier);
43 (*((void (*) (void)) *f)) ();
50 static bool allow_execstack = true;
56 /* Check whether SELinux is enabled and disallows executable stacks. */
57 FILE *fp = fopen ("/selinux/enforce", "r");
64 ssize_t n = getline (&line, &linelen, fp);
65 if (n > 0 && line[0] != '0')
72 fp = fopen ("/selinux/booleans/allow_execstack", "r");
75 n = getline (&line, &linelen, fp);
76 if (n > 0 && line[0] == '0')
77 allow_execstack = false;
84 printf ("executable stacks %sallowed\n", allow_execstack ? "" : "not ");
86 static void *f; /* Address of this is used in other threads. */
89 /* Create some threads while stacks are nonexecutable. */
93 pthread_barrier_init (&startup_barrier, NULL, N + 1);
94 pthread_barrier_init (&go_barrier, NULL, N + 1);
96 for (int i = 0; i < N; ++i)
98 int rc = pthread_create (&thr[i], NULL, &waiter_thread, &f);
100 error (1, rc, "pthread_create");
103 /* Make sure they are all there using their stacks. */
104 pthread_barrier_wait (&startup_barrier);
105 puts ("threads waiting");
110 /* Loading this module should force stacks to become executable. */
111 void *h = dlopen ("tst-execstack-mod.so", RTLD_LAZY);
114 printf ("cannot load: %s\n", dlerror ());
115 return allow_execstack;
118 f = dlsym (h, "tryme");
121 printf ("symbol not found: %s\n", dlerror ());
125 /* Test if that really made our stack executable.
126 The `tryme' function should crash if not. */
128 (*((void (*) (void)) f)) ();
132 /* Test that growing the stack region gets new executable pages too. */
133 deeper ((void (*) (void)) f);
138 /* Test that a fresh thread now gets an executable stack. */
141 int rc = pthread_create (&th, NULL, &tryme_thread, f);
143 error (1, rc, "pthread_create");
147 /* The existing threads' stacks should have been changed.
148 Let them run to test it. */
149 pthread_barrier_wait (&go_barrier);
151 pthread_exit ((void *) (long int) (! allow_execstack));
154 return ! allow_execstack;
158 deeper (void (*f) (void))
160 char stack[1100 * 1024];
161 memfrob (stack, sizeof stack);
163 memfrob (stack, sizeof stack);
167 #define TEST_FUNCTION do_test ()
168 #include "../test-skeleton.c"