[PATCH] close mprotect noexec hole

[Ulrich Drepper]

The following patch closes the hole in mprotect discovered during
the noexec mount discussions.  Without this the protection is
incomplete and pretty much useless.  With it and additional techniques
like SELinux all holes can be plugged in a fine-grained way.

I think it should be in .19 since it's a security problem not to have
it.  Tested on x86-64.


Signed-off-by: Ulrich Drepper <drepper@xxxxxxxxxx>

--- mm/mprotect.c	2006-10-01 09:35:14.000000000 -0700
+++ mm/mprotect.c-new	2006-10-11 14:54:55.000000000 -0700
@@ -251,6 +251,10 @@
 	error = -ENOMEM;
 	if (!vma)
 		goto out;
+	error = -EACCES;
+	if ((reqprot & PROT_EXEC) && vma->vm_file &&
+	    (vma->vm_file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
+		goto out;
 	if (unlikely(grows & PROT_GROWSDOWN)) {
 		if (vma->vm_start >= end)
 			goto out;
-
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