[Xen-changelog] Prevent a guest from specifying its own domain id when

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID b246f429f683cce73bf7486c37bf6842983fa49f
# Parent  6ba371536f5cbc2f0973c0e86881fec337828638
Prevent a guest from specifying its own domain id when
making a 'foreign' page mapping. It must use DOMID_SELF.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r 6ba371536f5c -r b246f429f683 xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Wed Feb  8 16:25:14 2006
+++ b/xen/arch/x86/mm.c Wed Feb  8 16:26:20 2006
@@ -1641,14 +1641,18 @@
     struct domain *e, *d = current->domain;
     int okay = 1;
 
-    if ( (e = percpu_info[cpu].foreign) != NULL )
-        put_domain(e);
-    percpu_info[cpu].foreign = NULL;
-    
-    if ( domid == DOMID_SELF )
+    ASSERT(percpu_info[cpu].foreign == NULL);
+
+    if ( likely(domid == DOMID_SELF) )
         goto out;
 
-    if ( !IS_PRIV(d) )
+    if ( domid == d->domain_id )
+    {
+        MEM_LOG("Dom %u tried to specify itself as foreign domain",
+                d->domain_id);
+        okay = 0;
+    }
+    else if ( !IS_PRIV(d) )
     {
         switch ( domid )
         {
@@ -1734,7 +1738,7 @@
 
     if ( !set_foreigndom(cpu, foreigndom) )
     {
-        rc = -EINVAL;
+        rc = -ESRCH;
         goto out;
     }
 
@@ -1993,7 +1997,7 @@
 
     if ( !set_foreigndom(cpu, foreigndom) )
     {
-        rc = -EINVAL;
+        rc = -ESRCH;
         goto out;
     }
 
@@ -2580,18 +2584,13 @@
                                      domid_t domid)
 {
     unsigned int cpu = smp_processor_id();
-    struct domain *d;
     int rc;
 
     if ( unlikely(!IS_PRIV(current->domain)) )
         return -EPERM;
 
-    percpu_info[cpu].foreign = d = find_domain_by_id(domid);
-    if ( unlikely(d == NULL) )
-    {
-        MEM_LOG("Unknown domain '%u'", domid);
+    if ( !set_foreigndom(cpu, domid) )
         return -ESRCH;
-    }
 
     rc = do_update_va_mapping(va, val64, flags);
 

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