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nptl: Move changing of stack permissions into ld.so

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All the stack lists are now in _rtld_global, so it is possible
to change stack permissions directly from there, instead of
calling into libpthread to do the change.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer
2021-05-10 10:31:41 +02:00
parent ee07b3a722
commit 2dd87703d4
9 changed files with 100 additions and 83 deletions
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76
sysdeps/unix/sysv/linux/dl-execstack.c
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@ -16,20 +16,21 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <ldsodefs.h>
#include <sys/mman.h>
#include <errno.h>
#include <ldsodefs.h>
#include <libintl.h>
#include <stdbool.h>
#include <list.h>
#include <nptl/pthreadP.h>
#include <stackinfo.h>
#include <stdbool.h>
#include <sys/mman.h>
#include <sysdep.h>
#include <unistd.h>
extern int __stack_prot attribute_relro attribute_hidden;
int
_dl_make_stack_executable (void **stack_endp)
static int
make_main_stack_executable (void **stack_endp)
{
/* This gives us the highest/lowest page that needs to be changed. */
uintptr_t page = ((uintptr_t) *stack_endp
@ -56,4 +57,63 @@ _dl_make_stack_executable (void **stack_endp)
return result;
}
rtld_hidden_def (_dl_make_stack_executable)
int
_dl_make_stacks_executable (void **stack_endp)
{
/* First the main thread's stack. */
int err = make_main_stack_executable (stack_endp);
if (err != 0)
return err;
lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
list_t *runp;
list_for_each (runp, &GL (dl_stack_used))
{
err = __nptl_change_stack_perm (list_entry (runp, struct pthread, list));
if (err != 0)
break;
}
/* Also change the permission for the currently unused stacks. This
might be wasted time but better spend it here than adding a check
in the fast path. */
if (err == 0)
list_for_each (runp, &GL (dl_stack_cache))
{
err = __nptl_change_stack_perm (list_entry (runp, struct pthread,
list));
if (err != 0)
break;
}
lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
return err;
}
int
__nptl_change_stack_perm (struct pthread *pd)
{
#ifdef NEED_SEPARATE_REGISTER_STACK
size_t pagemask = __getpagesize () - 1;
void *stack = (pd->stackblock
+ (((((pd->stackblock_size - pd->guardsize) / 2)
& pagemask) + pd->guardsize) & pagemask));
size_t len = pd->stackblock + pd->stackblock_size - stack;
#elif _STACK_GROWS_DOWN
void *stack = pd->stackblock + pd->guardsize;
size_t len = pd->stackblock_size - pd->guardsize;
#elif _STACK_GROWS_UP
void *stack = pd->stackblock;
size_t len = (uintptr_t) pd - pd->guardsize - (uintptr_t) pd->stackblock;
#else
# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
#endif
if (__mprotect (stack, len, PROT_READ | PROT_WRITE | PROT_EXEC) != 0)
return errno;
return 0;
}
rtld_hidden_def (__nptl_change_stack_perm)