PERFORCE change 14863 for review

[Brian Feldman]

http://people.freebsd.org/~peter/p4db/chv.cgi?CH=14863

Change 14863 by green at green_laptop_2 on 2002/07/24 13:48:51

	Change vm_mmap(9) semantics to remove all non-MAC-policy-specified
	protections from the maximum protections on the mapping and to
	reject the mapping if the protections requested are not a subset
	of such protections allowed.

Affected files ...

.. //depot/projects/trustedbsd/mac/sys/vm/vm_mmap.c#10 edit

Differences ...

==== //depot/projects/trustedbsd/mac/sys/vm/vm_mmap.c#10 (text+ko) ====

@@ -426,14 +426,25 @@
 #ifdef MAC
 	if (handle != NULL) {
 		if (flags & MAP_SHARED) {
+			/*
+			 * Decrease maximum allowed protection that may be
+			 * used with mprotect(2) later to that which the
+			 * policies might allow "at the moment".  This
+			 * should possibly be revoked or limited further
+			 * in mprotect(2).
+			 * 
+			 * Make sure that prot is within the scope of
+			 * what policies will allow, or fail immediately.
+			 */
 			vm_prot_t macmaxprot;
 
 			macmaxprot = mac_cred_check_mmap_vnode_prot(
 			    td->td_ucred, (struct vnode *)handle, 1);
-			if ((maxprot & macmaxprot) != maxprot) {
-				error = EPERM;
+			if ((prot & macmaxprot) != prot) {
+				error = EACCES;
 				goto done;
 			}
+			maxprot &= macmaxprot;
 		}
 		/*
 		 * XXX Policies (e.g. LOMAC) should possibly check for a read
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