igb: check timestamp validity

Add a couple of checks to make sure timestamping is on and that the
timestamp value from DMA is valid. This avoids any functional issues
that could come from a misinterpreted time stamp.

One of the functions changed doesn't need a return value added because
there was no value in checking from the calling locations.

While here, fix a couple of reverse christmas tree issues next to
the code being changed.

Fixes: f56e7bba ("igb: Pull timestamp from fragment before adding it to skb")
Fixes: 9cbc948b ("igb: add XDP support")
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Dave Switzer <david.switzer@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igb/igb.h

@@ -748,7 +748,7 @@ void igb_ptp_suspend(struct igb_adapter *adapter);
 void igb_ptp_rx_hang(struct igb_adapter *adapter);
 void igb_ptp_tx_hang(struct igb_adapter *adapter);
 void igb_ptp_rx_rgtstamp(struct igb_q_vector *q_vector, struct sk_buff *skb);
-void igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
+int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
 			struct sk_buff *skb);
 int igb_ptp_set_ts_config(struct net_device *netdev, struct ifreq *ifr);
 int igb_ptp_get_ts_config(struct net_device *netdev, struct ifreq *ifr);

drivers/net/ethernet/intel/igb/igb_main.c

@@ -8302,10 +8302,11 @@ static struct sk_buff *igb_construct_skb(struct igb_ring *rx_ring,
 		return NULL;
 
 	if (unlikely(igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP))) {
-		igb_ptp_rx_pktstamp(rx_ring->q_vector, xdp->data, skb);
+		if (!igb_ptp_rx_pktstamp(rx_ring->q_vector, xdp->data, skb)) {
 			xdp->data += IGB_TS_HDR_LEN;
 			size -= IGB_TS_HDR_LEN;
 		}
+	}
 
 	/* Determine available headroom for copy */
 	headlen = size;
@@ -8365,7 +8366,7 @@ static struct sk_buff *igb_build_skb(struct igb_ring *rx_ring,
 
 	/* pull timestamp out of packet data */
 	if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
-		igb_ptp_rx_pktstamp(rx_ring->q_vector, skb->data, skb);
+		if (!igb_ptp_rx_pktstamp(rx_ring->q_vector, skb->data, skb))
 			__skb_pull(skb, IGB_TS_HDR_LEN);
 	}
 

drivers/net/ethernet/intel/igb/igb_ptp.c

@@ -856,6 +856,9 @@ static void igb_ptp_tx_hwtstamp(struct igb_adapter *adapter)
 	dev_kfree_skb_any(skb);
 }
 
+#define IGB_RET_PTP_DISABLED 1
+#define IGB_RET_PTP_INVALID 2
+
 /**
  * igb_ptp_rx_pktstamp - retrieve Rx per packet timestamp
  * @q_vector: Pointer to interrupt specific structure
@@ -864,19 +867,29 @@ static void igb_ptp_tx_hwtstamp(struct igb_adapter *adapter)
  *
  * This function is meant to retrieve a timestamp from the first buffer of an
  * incoming frame.  The value is stored in little endian format starting on
- * byte 8.
+ * byte 8
+ *
+ * Returns: 0 if success, nonzero if failure
  **/
-void igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
+int igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
 			struct sk_buff *skb)
 {
-	__le64 *regval = (__le64 *)va;
 	struct igb_adapter *adapter = q_vector->adapter;
+	__le64 *regval = (__le64 *)va;
 	int adjust = 0;
 
+	if (!(adapter->ptp_flags & IGB_PTP_ENABLED))
+		return IGB_RET_PTP_DISABLED;
+
 	/* The timestamp is recorded in little endian format.
 	 * DWORD: 0        1        2        3
 	 * Field: Reserved Reserved SYSTIML  SYSTIMH
 	 */
+
+	/* check reserved dwords are zero, be/le doesn't matter for zero */
+	if (regval[0])
+		return IGB_RET_PTP_INVALID;
+
 	igb_ptp_systim_to_hwtstamp(adapter, skb_hwtstamps(skb),
 				   le64_to_cpu(regval[1]));
 
@@ -896,6 +909,8 @@ void igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
 	}
 	skb_hwtstamps(skb)->hwtstamp =
 		ktime_sub_ns(skb_hwtstamps(skb)->hwtstamp, adjust);
+
+	return 0;
 }
 
 /**
@@ -906,13 +921,15 @@ void igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector, void *va,
  * This function is meant to retrieve a timestamp from the internal registers
  * of the adapter and store it in the skb.
  **/
-void igb_ptp_rx_rgtstamp(struct igb_q_vector *q_vector,
-			 struct sk_buff *skb)
+void igb_ptp_rx_rgtstamp(struct igb_q_vector *q_vector, struct sk_buff *skb)
 {
 	struct igb_adapter *adapter = q_vector->adapter;
 	struct e1000_hw *hw = &adapter->hw;
-	u64 regval;
 	int adjust = 0;
+	u64 regval;
+
+	if (!(adapter->ptp_flags & IGB_PTP_ENABLED))
+		return;
 
 	/* If this bit is set, then the RX registers contain the time stamp. No
 	 * other packet will be time stamped until we read these registers, so