1 files changed, 87 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
index 69644b621b45..b35c61ccc64a 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
@@ -3841,6 +3841,87 @@ static int i40e_check_fdir_input_set(struct i40e_vsi *vsi,
 }
 
 /**
+ * i40e_match_fdir_filter - Return true of two filters match
+ * @a: pointer to filter struct
+ * @b: pointer to filter struct
+ *
+ * Returns true if the two filters match exactly the same criteria. I.e. they
+ * match the same flow type and have the same parameters. We don't need to
+ * check any input-set since all filters of the same flow type must use the
+ * same input set.
+ **/
+static bool i40e_match_fdir_filter(struct i40e_fdir_filter *a,
+				   struct i40e_fdir_filter *b)
+{
+	/* The filters do not much if any of these criteria differ. */
+	if (a->dst_ip != b->dst_ip ||
+	    a->src_ip != b->src_ip ||
+	    a->dst_port != b->dst_port ||
+	    a->src_port != b->src_port ||
+	    a->flow_type != b->flow_type ||
+	    a->ip4_proto != b->ip4_proto)
+		return false;
+
+	return true;
+}
+
+/**
+ * i40e_disallow_matching_filters - Check that new filters differ
+ * @vsi: pointer to the targeted VSI
+ * @input: new filter to check
+ *
+ * Due to hardware limitations, it is not possible for two filters that match
+ * similar criteria to be programmed at the same time. This is true for a few
+ * reasons:
+ *
+ * (a) all filters matching a particular flow type must use the same input
+ * set, that is they must match the same criteria.
+ * (b) different flow types will never match the same packet, as the flow type
+ * is decided by hardware before checking which rules apply.
+ * (c) hardware has no way to distinguish which order filters apply in.
+ *
+ * Due to this, we can't really support using the location data to order
+ * filters in the hardware parsing. It is technically possible for the user to
+ * request two filters matching the same criteria but which select different
+ * queues. In this case, rather than keep both filters in the list, we reject
+ * the 2nd filter when the user requests adding it.
+ *
+ * This avoids needing to track location for programming the filter to
+ * hardware, and ensures that we avoid some strange scenarios involving
+ * deleting filters which match the same criteria.
+ **/
+static int i40e_disallow_matching_filters(struct i40e_vsi *vsi,
+					  struct i40e_fdir_filter *input)
+{
+	struct i40e_pf *pf = vsi->back;
+	struct i40e_fdir_filter *rule;
+	struct hlist_node *node2;
+
+	/* Loop through every filter, and check that it doesn't match */
+	hlist_for_each_entry_safe(rule, node2,
+				  &pf->fdir_filter_list, fdir_node) {
+		/* Don't check the filters match if they share the same fd_id,
+		 * since the new filter is actually just updating the target
+		 * of the old filter.
+		 */
+		if (rule->fd_id == input->fd_id)
+			continue;
+
+		/* If any filters match, then print a warning message to the
+		 * kernel message buffer and bail out.
+		 */
+		if (i40e_match_fdir_filter(rule, input)) {
+			dev_warn(&pf->pdev->dev,
+				 "Existing user defined filter %d already matches this flow.\n",
+				 rule->fd_id);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/**
  * i40e_add_fdir_ethtool - Add/Remove Flow Director filters
  * @vsi: pointer to the targeted VSI
  * @cmd: command to get or set RX flow classification rules
@@ -3952,6 +4033,11 @@ static int i40e_add_fdir_ethtool(struct i40e_vsi *vsi,
 		input->flex_offset = userdef.flex_offset;
 	}
 
+	/* Avoid programming two filters with identical match criteria. */
+	ret = i40e_disallow_matching_filters(vsi, input);
+	if (ret)
+		goto free_filter_memory;
+
 	/* Add the input filter to the fdir_input_list, possibly replacing
 	 * a previous filter. Do not free the input structure after adding it
 	 * to the list as this would cause a use-after-free bug.
@@ -3965,6 +4051,7 @@ static int i40e_add_fdir_ethtool(struct i40e_vsi *vsi,
 remove_sw_rule:
 	hlist_del(&input->fdir_node);
 	pf->fdir_pf_active_filters--;
+free_filter_memory:
 	kfree(input);
 	return ret;
 }