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From: Hubertus Franke <frankeh@watson.ibm.com>
Reply-To: frankeh@watson.ibm.com
Organization: IBM Research
To: Andrew Morton <akpm@digeo.com>
Subject: [PATCH] recognize MAP_LOCKED in mmap() call
Date: Wed, 18 Sep 2002 12:07:26 -0400
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Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
References: <3D815C8C.4050000@us.ibm.com> <1031922352.9056.14.camel@irongate.swansea.linux.org.uk> <20020913213042.GD3530@holomorphy.com>
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Andrew, at the current time an mmap() ignores a MAP_LOCKED passed to it.
The only way we can get VM_LOCKED associated with the newly created VMA
is to have previously called mlockall() on the process which sets the 
mm->def_flags != VM_LOCKED or subsequently call mlock() on the
newly created VMA.

The attached patch checks for MAP_LOCKED being passed and if so checks
the capabilities of the process. Limit checks were already in place.
-- 
-- Hubertus Franke  (frankeh@watson.ibm.com)

--------------------------------< PATCH >------------------------------
--- linux-2.5.35/mm/mmap.c	Wed Sep 18 11:12:13 2002
+++ linux-2.5.35-fix/mm/mmap.c	Wed Sep 18 11:44:32 2002
@@ -461,6 +461,11 @@
 	 */
 	vm_flags = calc_vm_flags(prot,flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 
+	if (flags & MAP_LOCKED) {
+		if (!capable(CAP_IPC_LOCK))
+			return -EPERM;
+		vm_flags |= VM_LOCKED;
+	}
 	/* mlock MCL_FUTURE? */
 	if (vm_flags & VM_LOCKED) {
 		unsigned long locked = mm->locked_vm << PAGE_SHIFT;




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--- linux-2.5.35/mm/mmap.c	Wed Sep 18 11:12:13 2002
+++ linux-2.5.35-fix/mm/mmap.c	Wed Sep 18 11:44:32 2002
@@ -461,6 +461,11 @@
 	 */
 	vm_flags = calc_vm_flags(prot,flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 
+	if (flags & MAP_LOCKED) {
+		if (!capable(CAP_IPC_LOCK))
+			return -EPERM;
+		vm_flags |= VM_LOCKED;
+	}
 	/* mlock MCL_FUTURE? */
 	if (vm_flags & VM_LOCKED) {
 		unsigned long locked = mm->locked_vm << PAGE_SHIFT;

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