thunderbolt: Introduce USB only (SL4) security level

This new security level works so that it creates one PCIe tunnel to the
connected Thunderbolt dock, removing PCIe links downstream of the dock.
This leaves only the internal USB controller visible.

Display Port tunnels are created normally.

While there make sure security sysfs attribute returns "unknown" for any
future security level.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

diff --git a/Documentation/ABI/testing/sysfs-bus-thunderbolt b/Documentation/ABI/testing/sysfs-bus-thunderbolt
index 4ed229789852673cc3bb0f9b3ae454bd95776304..151584a1f9504d5fb00dc8c6190a0aa479ad2287 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-thunderbolt
+++ b/Documentation/ABI/testing/sysfs-bus-thunderbolt
@@ -35,6 +35,9 @@ Description:  This attribute holds current Thunderbolt security level
                        minimum. User needs to authorize each device.
                dponly: Automatically tunnel Display port (and USB). No
                        PCIe tunnels are created.
+               usbonly: Automatically tunnel USB controller of the
+                        connected Thunderbolt dock (and Display Port). All
+                        PCIe links downstream of the dock are removed.
 
 What: /sys/bus/thunderbolt/devices/.../authorized
 Date:          Sep 2017

diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst
index 9948ec36a204f9927821f529f57353b046efee38..35fccba6a9a6b4d247e590f8a9e535203015b2b4 100644 (file)
--- a/Documentation/admin-guide/thunderbolt.rst
+++ b/Documentation/admin-guide/thunderbolt.rst
@@ -21,11 +21,11 @@ vulnerable to DMA attacks.
 Security levels and how to use them
 -----------------------------------
 Starting with Intel Falcon Ridge Thunderbolt controller there are 4
-security levels available. The reason for these is the fact that the
-connected devices can be DMA masters and thus read contents of the host
-memory without CPU and OS knowing about it. There are ways to prevent
-this by setting up an IOMMU but it is not always available for various
-reasons.
+security levels available. Intel Titan Ridge added one more security level
+(usbonly). The reason for these is the fact that the connected devices can
+be DMA masters and thus read contents of the host memory without CPU and OS
+knowing about it. There are ways to prevent this by setting up an IOMMU but
+it is not always available for various reasons.
 
 The security levels are as follows:
 
@@ -52,6 +52,11 @@ The security levels are as follows:
     USB. No PCIe tunneling is done. In BIOS settings this is
     typically called *Display Port Only*.
 
+  usbonly
+    The firmware automatically creates tunnels for the USB controller and
+    Display Port in a dock. All PCIe links downstream of the dock are
+    removed.
+
 The current security level can be read from
 ``/sys/bus/thunderbolt/devices/domainX/security`` where ``domainX`` is
 the Thunderbolt domain the host controller manages. There is typically

diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c
index ab4b304306f7c8907cc0d77994172ecf0303e40c..6281266b8ec0a15721da5196b641b707b8a5c973 100644 (file)
--- a/drivers/thunderbolt/domain.c
+++ b/drivers/thunderbolt/domain.c
@@ -117,6 +117,7 @@ static const char * const tb_security_names[] = {
        [TB_SECURITY_USER] = "user",
        [TB_SECURITY_SECURE] = "secure",
        [TB_SECURITY_DPONLY] = "dponly",
+       [TB_SECURITY_USBONLY] = "usbonly",
 };
 
 static ssize_t boot_acl_show(struct device *dev, struct device_attribute *attr,
@@ -227,8 +228,12 @@ static ssize_t security_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
 {
        struct tb *tb = container_of(dev, struct tb, dev);
+       const char *name = "unknown";
 
-       return sprintf(buf, "%s\n", tb_security_names[tb->security_level]);
+       if (tb->security_level < ARRAY_SIZE(tb_security_names))
+               name = tb_security_names[tb->security_level];
+
+       return sprintf(buf, "%s\n", name);
 }
 static DEVICE_ATTR_RO(security);
 

diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
index 47251844d064820b8453d9a18c28feab418c2b45..a3ed26082bc1d8ba316074b4b1c5475866948084 100644 (file)
--- a/include/linux/thunderbolt.h
+++ b/include/linux/thunderbolt.h
@@ -45,12 +45,16 @@ enum tb_cfg_pkg_type {
  * @TB_SECURITY_USER: User approval required at minimum
  * @TB_SECURITY_SECURE: One time saved key required at minimum
  * @TB_SECURITY_DPONLY: Only tunnel Display port (and USB)
+ * @TB_SECURITY_USBONLY: Only tunnel USB controller of the connected
+ *                      Thunderbolt dock (and Display Port). All PCIe
+ *                      links downstream of the dock are removed.
  */
 enum tb_security_level {
        TB_SECURITY_NONE,
        TB_SECURITY_USER,
        TB_SECURITY_SECURE,
        TB_SECURITY_DPONLY,
+       TB_SECURITY_USBONLY,
 };
 
 /**