2003-09-23 Roland McGrath <roland@redhat.com>

	* sysdeps/generic/ldsodefs.h (struct rtld_global): Add _dl_stack_flags
	and _dl_make_stack_executable_hook.  Declare _dl_make_stack_executable.
	* elf/rtld.c (_rtld_global): Add initializer for _dl_stack_flags.
	(dl_main): Reset _dl_stack_flags according to PT_GNU_STACK phdr.
	Initialize _dl_make_stack_executable_hook.
	* elf/dl-support.c: Define those new variables.
	(_dl_non_dynamic_init): Scan phdrs for PT_GNU_STACK.
	(_dl_phdr): Fix type.
	* elf/dl-load.c (_dl_map_object_from_fd): Grok PT_GNU_STACK phdr and
	enable execute permission for the stack if necessary.
	* sysdeps/generic/dl-execstack.c: New file.
	* elf/Makefile (dl-routines): Add it.
	* elf/Versions (ld: GLIBC_PRIVATE): Add _dl_make_stack_executable.
	* sysdeps/unix/sysv/linux/dl-execstack.c: New file.

1 files changed, 19 insertions, 0 deletions

diff --git a/elf/dl-support.c b/elf/dl-support.c
index 8c58b2ba69..448f4c6848 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -129,6 +129,16 @@ ElfW(Phdr) *_dl_phdr;
 size_t _dl_phnum;
 unsigned long int _dl_hwcap __attribute__ ((nocommon));
 
+/* Prevailing state of the stack, PF_X indicating it's executable.  */
+ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X;
+
+/* If loading a shared object requires that we make the stack executable
+   when it was not, we do it by calling this function.
+   It returns an errno code or zero on success.  */
+int (*_dl_make_stack_executable_hook) (void) internal_function
+  = _dl_make_stack_executable;
+
+
 #ifdef NEED_DL_SYSINFO
 /* Needed for improved syscall handling on at least x86/Linux.  */
 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
@@ -264,6 +274,15 @@ _dl_non_dynamic_init (void)
   /* Now determine the length of the platform string.  */
   if (_dl_platform != NULL)
     _dl_platformlen = strlen (_dl_platform);
+
+  /* Scan for a program header telling us the stack is nonexecutable.  */
+  if (_dl_phdr != NULL)
+    for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
+      if (_dl_phdr[i].p_type == PT_GNU_STACK)
+	{
+	  _dl_stack_flags = _dl_phdr[i].p_flags;
+	  break;
+	}
 }