net: openvswitch: Support masked set actions.

OVS userspace already probes the openvswitch kernel module for
OVS_ACTION_ATTR_SET_MASKED support.  This patch adds the kernel module
implementation of masked set actions.

The existing set action sets many fields at once.  When only a subset
of the IP header fields, for example, should be modified, all the IP
fields need to be exact matched so that the other field values can be
copied to the set action.  A masked set action allows modification of
an arbitrary subset of the supported header bits without requiring the
rest to be matched.

Masked set action is now supported for all writeable key types, except
for the tunnel key.  The set tunnel action is an exception as any
input tunnel info is cleared before action processing starts, so there
is no tunnel info to mask.

The kernel module converts all (non-tunnel) set actions to masked set
actions.  This makes action processing more uniform, and results in
less branching and duplicating the action processing code.  When
returning actions to userspace, the fully masked set actions are
converted back to normal set actions.  We use a kernel internal action
code to be able to tell the userspace provided and converted masked
set actions apart.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/openvswitch.h

@@ -599,6 +599,12 @@ struct ovs_action_hash {
  * @OVS_ACTION_ATTR_SET: Replaces the contents of an existing header.  The
  * single nested %OVS_KEY_ATTR_* attribute specifies a header to modify and its
  * value.
+ * @OVS_ACTION_ATTR_SET_MASKED: Replaces the contents of an existing header.  A
+ * nested %OVS_KEY_ATTR_* attribute specifies a header to modify, its value,
+ * and a mask.  For every bit set in the mask, the corresponding bit value
+ * is copied from the value to the packet header field, rest of the bits are
+ * left unchanged.  The non-masked value bits must be passed in as zeroes.
+ * Masking is not supported for the %OVS_KEY_ATTR_TUNNEL attribute.
  * @OVS_ACTION_ATTR_PUSH_VLAN: Push a new outermost 802.1Q header onto the
  * packet.
  * @OVS_ACTION_ATTR_POP_VLAN: Pop the outermost 802.1Q header off the packet.
@@ -617,6 +623,9 @@ struct ovs_action_hash {
  * Only a single header can be set with a single %OVS_ACTION_ATTR_SET.  Not all
  * fields within a header are modifiable, e.g. the IPv4 protocol and fragment
  * type may not be changed.
+ *
+ * @OVS_ACTION_ATTR_SET_TO_MASKED: Kernel internal masked set action translated
+ * from the @OVS_ACTION_ATTR_SET.
  */
 
 enum ovs_action_attr {
@@ -631,8 +640,19 @@ enum ovs_action_attr {
 	OVS_ACTION_ATTR_HASH,	      /* struct ovs_action_hash. */
 	OVS_ACTION_ATTR_PUSH_MPLS,    /* struct ovs_action_push_mpls. */
 	OVS_ACTION_ATTR_POP_MPLS,     /* __be16 ethertype. */
+	OVS_ACTION_ATTR_SET_MASKED,   /* One nested OVS_KEY_ATTR_* including
+				       * data immediately followed by a mask.
+				       * The data must be zero for the unmasked
+				       * bits. */
+
+	__OVS_ACTION_ATTR_MAX,	      /* Nothing past this will be accepted
+				       * from userspace. */
 
-	__OVS_ACTION_ATTR_MAX
+#ifdef __KERNEL__
+	OVS_ACTION_ATTR_SET_TO_MASKED, /* Kernel module internal masked
+					* set action converted from
+					* OVS_ACTION_ATTR_SET. */
+#endif
 };
 
 #define OVS_ACTION_ATTR_MAX (__OVS_ACTION_ATTR_MAX - 1)