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169 lines
3.4 KiB
C
169 lines
3.4 KiB
C
/* Test program for making nonexecutable stacks executable
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on load of a DSO that requires executable stacks. */
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#include <dlfcn.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <error.h>
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static void
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print_maps (void)
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{
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#if 0
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char *cmd = NULL;
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asprintf (&cmd, "cat /proc/%d/maps", getpid ());
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system (cmd);
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free (cmd);
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#endif
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}
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static void deeper (void (*f) (void));
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#if USE_PTHREADS
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# include <pthread.h>
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static void *
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tryme_thread (void *f)
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{
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(*((void (*) (void)) f)) ();
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return 0;
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}
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static pthread_barrier_t startup_barrier, go_barrier;
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static void *
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waiter_thread (void *arg)
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{
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void **f = arg;
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pthread_barrier_wait (&startup_barrier);
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pthread_barrier_wait (&go_barrier);
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(*((void (*) (void)) *f)) ();
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return 0;
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}
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#endif
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static bool allow_execstack = true;
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static int
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do_test (void)
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{
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/* Check whether SELinux is enabled and disallows executable stacks. */
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FILE *fp = fopen ("/selinux/enforce", "r");
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if (fp != NULL)
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{
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char *line = NULL;
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size_t linelen = 0;
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bool enabled = false;
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ssize_t n = getline (&line, &linelen, fp);
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if (n > 0 && line[0] != '0')
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enabled = true;
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fclose (fp);
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if (enabled)
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{
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fp = fopen ("/selinux/booleans/allow_execstack", "r");
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if (fp != NULL)
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{
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n = getline (&line, &linelen, fp);
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if (n > 0 && line[0] == '0')
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allow_execstack = false;
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}
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fclose (fp);
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}
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}
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printf ("executable stacks %sallowed\n", allow_execstack ? "" : "not ");
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static void *f; /* Address of this is used in other threads. */
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#if USE_PTHREADS
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/* Create some threads while stacks are nonexecutable. */
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#define N 5
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pthread_t thr[N];
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pthread_barrier_init (&startup_barrier, NULL, N + 1);
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pthread_barrier_init (&go_barrier, NULL, N + 1);
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for (int i = 0; i < N; ++i)
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{
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int rc = pthread_create (&thr[i], NULL, &waiter_thread, &f);
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if (rc)
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error (1, rc, "pthread_create");
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}
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/* Make sure they are all there using their stacks. */
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pthread_barrier_wait (&startup_barrier);
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puts ("threads waiting");
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#endif
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print_maps ();
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/* Loading this module should force stacks to become executable. */
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void *h = dlopen ("tst-execstack-mod.so", RTLD_LAZY);
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if (h == NULL)
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{
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printf ("cannot load: %s\n", dlerror ());
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return allow_execstack;
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}
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f = dlsym (h, "tryme");
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if (f == NULL)
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{
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printf ("symbol not found: %s\n", dlerror ());
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return 1;
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}
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/* Test if that really made our stack executable.
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The `tryme' function should crash if not. */
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(*((void (*) (void)) f)) ();
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print_maps ();
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/* Test that growing the stack region gets new executable pages too. */
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deeper ((void (*) (void)) f);
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print_maps ();
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#if USE_PTHREADS
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/* Test that a fresh thread now gets an executable stack. */
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{
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pthread_t th;
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int rc = pthread_create (&th, NULL, &tryme_thread, f);
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if (rc)
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error (1, rc, "pthread_create");
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}
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puts ("threads go");
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/* The existing threads' stacks should have been changed.
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Let them run to test it. */
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pthread_barrier_wait (&go_barrier);
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pthread_exit ((void *) (long int) (! allow_execstack));
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#endif
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return ! allow_execstack;
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}
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static void
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deeper (void (*f) (void))
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{
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char stack[1100 * 1024];
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memfrob (stack, sizeof stack);
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(*f) ();
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memfrob (stack, sizeof stack);
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}
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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