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, 20 insertions, 0 deletions

diff --git a/elf/dl-load.c b/elf/dl-load.c
index 249ef84..0b6e96f 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -904,6 +904,9 @@ _dl_map_object_from_fd (const char *name, int fd, struct filebuf *fbp,
 	}
     }
 
+  /* Presumed absent PT_GNU_STACK.  */
+  uint_fast16_t stack_flags = PF_R|PF_W|PF_X;
+
   {
     /* Scan the program header table, collecting its load commands.  */
     struct loadcmd
@@ -1058,6 +1061,10 @@ cannot allocate TLS data structures for initial thread");
 	  errstring = N_("cannot handle TLS data");
 	  goto call_lose;
 	  break;
+
+	case PT_GNU_STACK:
+	  stack_flags = ph->p_flags;
+	  break;
 	}
 
     if (__builtin_expect (nloadcmds == 0, 0))
@@ -1334,6 +1341,19 @@ cannot allocate TLS data structures for initial thread");
   l->l_dev = st.st_dev;
   l->l_ino = st.st_ino;
 
+  if (__builtin_expect ((stack_flags &~ GL(dl_stack_flags)) & PF_X, 0))
+    {
+      /* The stack is presently not executable, but this module
+	 requires that it be executable.  */
+      errval = (*GL(dl_make_stack_executable_hook)) ();
+      if (errval)
+	{
+	  errstring = N_("\
+cannot enable executable stack as shared object requires");
+	  goto call_lose;
+	}
+    }
+
   /* When we profile the SONAME might be needed for something else but
      loading.  Add it right away.  */
   if (__builtin_expect (GL(dl_profile) != NULL, 0)