[Xen-devel] [PATCH 1/2] xen/xsm: forbid PV guest console reads

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

When the hypervisor was compiled in debug mode (with VERBOSE defined),
PV guests incorrectly had access to both read and write to the console.
Change this to only allow write access; since such writes were limited
by log levels in 48d50de8e0, remove the dependency on VERBOSE
completely.

Reported-by: Jan Beulich <JBeulich@xxxxxxxx>
Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
---

Alternatively, if controlling writes with VERBOSE is still desired, the
ifdef VERBOSE can be retained surrounding the if() with the following
commit message:

The CONSOLEIO_read operation was incorrectly allowed to PV guests if the
hypervisor was compiled in debug mode (with VERBOSE defined).

 xen/include/xsm/dummy.h | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index 052f3e0..1f4960d 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -221,11 +221,9 @@ static XSM_INLINE int 
xsm_memory_stat_reservation(XSM_DEFAULT_ARG struct domain
 static XSM_INLINE int xsm_console_io(XSM_DEFAULT_ARG struct domain *d, int cmd)
 {
     XSM_ASSERT_ACTION(XSM_OTHER);
-#ifdef VERBOSE
-    return xsm_default_action(XSM_HOOK, current->domain, NULL);
-#else
-    return xsm_default_action(XSM_PRIV, current->domain, NULL);
-#endif
+    if ( cmd == CONSOLEIO_write )
+        return xsm_default_action(XSM_HOOK, d, NULL);
+    return xsm_default_action(XSM_PRIV, d, NULL);
 }
 
 static XSM_INLINE int xsm_profile(XSM_DEFAULT_ARG struct domain *d, int op)
-- 
1.8.1.4


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