sysdeps/unix/sysv/linux/x86/tst-cet-setcontext-1.c

   1 /* Check getcontext and setcontext on the context from makecontext
   2    with shadow stack.
   3    Copyright (C) 2018-2024 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <stdio.h>
  21 #include <stdint.h>
  22 #include <stdlib.h>
  23 #include <ucontext.h>
  24 #include <unistd.h>
  25 #include <sys/mman.h>
  26 #include <stdatomic.h>
  27 #include <x86intrin.h>
  28
  29 static ucontext_t ctx[5];
  30 static atomic_int done;
  31
  32 static void
  33 __attribute__((noinline, noclone))
  34 f2 (void)
  35 {
  36   printf ("start f2\n");
  37   done++;
  38   if (setcontext (&ctx[2]) != 0)
  39     {
  40       printf ("%s: setcontext: %m\n", __FUNCTION__);
  41       exit (EXIT_FAILURE);
  42     }
  43 }
  44
  45 static void
  46 f1 (void)
  47 {
  48   printf ("start f1\n");
  49   if (getcontext (&ctx[2]) != 0)
  50     {
  51       printf ("%s: getcontext: %m\n", __FUNCTION__);
  52       exit (EXIT_FAILURE);
  53     }
  54   if (done)
  55     exit (EXIT_SUCCESS);
  56   f2 ();
  57 }
  58
  59 static int
  60 do_test (void)
  61 {
  62   char st1[32768];
  63   puts ("making contexts");
  64   if (getcontext (&ctx[0]) != 0)
  65     {
  66       printf ("%s: getcontext: %m\n", __FUNCTION__);
  67       exit (EXIT_FAILURE);
  68     }
  69   if (getcontext (&ctx[1]) != 0)
  70     {
  71       printf ("%s: getcontext: %m\n", __FUNCTION__);
  72       exit (EXIT_FAILURE);
  73     }
  74
  75   ctx[3].uc_stack.ss_sp = st1;
  76   ctx[3].uc_stack.ss_size = sizeof st1;
  77   ctx[3].uc_link = &ctx[0];
  78   makecontext (&ctx[3], (void (*) (void)) f1, 0);
  79
  80   ctx[1].uc_stack.ss_sp = st1;
  81   ctx[1].uc_stack.ss_size = sizeof st1;
  82   ctx[1].uc_link = &ctx[0];
  83   makecontext (&ctx[1], (void (*) (void)) f1, 0);
  84
  85   ctx[4].uc_stack.ss_sp = st1;
  86   ctx[4].uc_stack.ss_size = sizeof st1;
  87   ctx[4].uc_link = &ctx[0];
  88   makecontext (&ctx[4], (void (*) (void)) f1, 0);
  89
  90   /* NB: When shadow stack is enabled, makecontext calls map_shadow_stack
  91      to allocate a new shadow stack which can be unmapped.  The base
  92      address and size of the new shadow stack are returned in __ssp[1]
  93      and __ssp[2].  makecontext is called for CTX1, CTX3 and CTX4.  But
  94      only CTX1 is used.  New shadow stacks are allocated in the order
  95      of CTX3, CTX1, CTX4.  It is very likely that CTX1's shadow stack is
  96      placed between CTX3 and CTX4.  We munmap CTX3's and CTX4's shadow
  97      stacks to create gaps above and below CTX1's shadow stack.  We check
  98      that setcontext CTX1 works correctly in this case.  */
  99   if (_get_ssp () != 0)
 100     {
 101       if (ctx[3].__ssp[1] != 0
 102           && munmap ((void *) (uintptr_t) ctx[3].__ssp[1],
 103                      (size_t) ctx[3].__ssp[2]) != 0)
 104         {
 105           printf ("%s: munmap: %m\n", __FUNCTION__);
 106           exit (EXIT_FAILURE);
 107         }
 108
 109       if (ctx[4].__ssp[1] != 0
 110           && munmap ((void *) (uintptr_t) ctx[4].__ssp[1],
 111                      (size_t) ctx[4].__ssp[2]) != 0)
 112         {
 113           printf ("%s: munmap: %m\n", __FUNCTION__);
 114           exit (EXIT_FAILURE);
 115         }
 116     }
 117
 118   if (setcontext (&ctx[1]) != 0)
 119     {
 120       printf ("%s: setcontext: %m\n", __FUNCTION__);
 121       exit (EXIT_FAILURE);
 122     }
 123   exit (EXIT_FAILURE);
 124 }
 125
 126 #include <support/test-driver.c>