ethtool: Block setting of symmetric RSS when non-symmetric rx-flow-hash is requested

Symmetric RSS hash requires that:
* No other fields besides IP src/dst and/or L4 src/dst are set
* If src is set, dst must also be set

This restriction was only enforced when RXNFC was configured after
symmetric hash was enabled. In the opposite order of operations (RXNFC
then symmetric enablement) the check was not performed.

Perform the sanity check on set_rxfh as well, by iterating over all flow
types hash fields and making sure they are all symmetric.

Introduce a function that returns whether a flow type is hashable (not
spec only) and needs to be iterated over. To make sure that no one
forgets to update the list of hashable flow types when adding new flow
types, a static assert is added to draw the developer's attention.

The conversion of uapi #defines to enum is not ideal, but as Jakub
mentioned [1], we have precedent for that.

[1] https://lore.kernel.org/netdev/20250324073509.6571ade3@kernel.org/

Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250508103034.885536-1-gal@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 89 insertions, 10 deletions

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 8262cc10f98d..39ec920f5de7 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -978,6 +978,88 @@ static int ethtool_rxnfc_copy_to_user(void __user *useraddr,
 	return 0;
 }
 
+static bool flow_type_hashable(u32 flow_type)
+{
+	switch (flow_type) {
+	case TCP_V4_FLOW:
+	case UDP_V4_FLOW:
+	case SCTP_V4_FLOW:
+	case AH_ESP_V4_FLOW:
+	case TCP_V6_FLOW:
+	case UDP_V6_FLOW:
+	case SCTP_V6_FLOW:
+	case AH_ESP_V6_FLOW:
+	case AH_V4_FLOW:
+	case ESP_V4_FLOW:
+	case AH_V6_FLOW:
+	case ESP_V6_FLOW:
+	case IPV4_FLOW:
+	case IPV6_FLOW:
+	case GTPU_V4_FLOW:
+	case GTPU_V6_FLOW:
+	case GTPC_V4_FLOW:
+	case GTPC_V6_FLOW:
+	case GTPC_TEID_V4_FLOW:
+	case GTPC_TEID_V6_FLOW:
+	case GTPU_EH_V4_FLOW:
+	case GTPU_EH_V6_FLOW:
+	case GTPU_UL_V4_FLOW:
+	case GTPU_UL_V6_FLOW:
+	case GTPU_DL_V4_FLOW:
+	case GTPU_DL_V6_FLOW:
+		return true;
+	}
+
+	return false;
+}
+
+/* When adding a new type, update the assert and, if it's hashable, add it to
+ * the flow_type_hashable switch case.
+ */
+static_assert(GTPU_DL_V6_FLOW + 1 == __FLOW_TYPE_COUNT);
+
+static int ethtool_check_xfrm_rxfh(u32 input_xfrm, u64 rxfh)
+{
+	/* Sanity check: if symmetric-xor/symmetric-or-xor is set, then:
+	 * 1 - no other fields besides IP src/dst and/or L4 src/dst are set
+	 * 2 - If src is set, dst must also be set
+	 */
+	if ((input_xfrm != RXH_XFRM_NO_CHANGE &&
+	     input_xfrm & (RXH_XFRM_SYM_XOR | RXH_XFRM_SYM_OR_XOR)) &&
+	    ((rxfh & ~(RXH_IP_SRC | RXH_IP_DST | RXH_L4_B_0_1 | RXH_L4_B_2_3)) ||
+	     (!!(rxfh & RXH_IP_SRC) ^ !!(rxfh & RXH_IP_DST)) ||
+	     (!!(rxfh & RXH_L4_B_0_1) ^ !!(rxfh & RXH_L4_B_2_3))))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ethtool_check_flow_types(struct net_device *dev, u32 input_xfrm)
+{
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	struct ethtool_rxnfc info = {
+		.cmd = ETHTOOL_GRXFH,
+	};
+	int err;
+	u32 i;
+
+	for (i = 0; i < __FLOW_TYPE_COUNT; i++) {
+		if (!flow_type_hashable(i))
+			continue;
+
+		info.flow_type = i;
+		err = ops->get_rxnfc(dev, &info, NULL);
+		if (err)
+			continue;
+
+		err = ethtool_check_xfrm_rxfh(input_xfrm, info.data);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
 						u32 cmd, void __user *useraddr)
 {
@@ -1012,16 +1094,9 @@ static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
 		if (rc)
 			return rc;
 
-		/* Sanity check: if symmetric-xor/symmetric-or-xor is set, then:
-		 * 1 - no other fields besides IP src/dst and/or L4 src/dst
-		 * 2 - If src is set, dst must also be set
-		 */
-		if ((rxfh.input_xfrm & (RXH_XFRM_SYM_XOR | RXH_XFRM_SYM_OR_XOR)) &&
-		    ((info.data & ~(RXH_IP_SRC | RXH_IP_DST |
-				    RXH_L4_B_0_1 | RXH_L4_B_2_3)) ||
-		     (!!(info.data & RXH_IP_SRC) ^ !!(info.data & RXH_IP_DST)) ||
-		     (!!(info.data & RXH_L4_B_0_1) ^ !!(info.data & RXH_L4_B_2_3))))
-			return -EINVAL;
+		rc = ethtool_check_xfrm_rxfh(rxfh.input_xfrm, info.data);
+		if (rc)
+			return rc;
 	}
 
 	rc = ops->set_rxnfc(dev, &info);
@@ -1413,6 +1488,10 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	     rxfh.input_xfrm == RXH_XFRM_NO_CHANGE))
 		return -EINVAL;
 
+	ret = ethtool_check_flow_types(dev, rxfh.input_xfrm);
+	if (ret)
+		return ret;
+
 	indir_bytes = dev_indir_size * sizeof(rxfh_dev.indir[0]);
 
 	/* Check settings which may be global rather than per RSS-context */