On Fri, 05 Sep 2025 10:07:23 -0700 Breno Leitao wrote:
> + int (*get_rxrings)(struct net_device *dev);
I think this can return u32..
The drivers can't possibly fail to know how many queues they have.
We already do that for get_rxfh_*_size callbacks
> void (*get_pause_stats)(struct net_device *dev,
> struct ethtool_pause_stats *pause_stats);
> void (*get_pauseparam)(struct net_device *,
> diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
> index 1a9ad47f60313..2f3dbef9eb712 100644
> --- a/net/ethtool/ioctl.c
> +++ b/net/ethtool/ioctl.c
> @@ -1208,6 +1208,22 @@ static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
> return 0;
> }
>
> +static int get_num_rxrings(struct net_device *dev)
This one has to indeed keep returning int, until we get rid of
get_rxnfc fallback completely.
> +{
> + const struct ethtool_ops *ops = dev->ethtool_ops;
> + struct ethtool_rxnfc rx_rings;
> + int ret;
> +
> + if (ops->get_rxrings)
> + return ops->get_rxrings(dev);
> +
> + ret = ops->get_rxnfc(dev, &rx_rings, NULL);
> + if (ret < 0)
> + return ret;
> +
> + return rx_rings.data;
> +}
> +
> static noinline_for_stack int ethtool_get_rxrings(struct net_device *dev,
> u32 cmd,
> void __user *useraddr)
> @@ -1217,16 +1233,17 @@ static noinline_for_stack int ethtool_get_rxrings(struct net_device *dev,
> const struct ethtool_ops *ops = dev->ethtool_ops;
> int ret;
>
> - if (!ops->get_rxnfc)
> + if (!ops->get_rxnfc && !ops->get_rxrings)
> return -EOPNOTSUPP;
>
> ret = ethtool_rxnfc_copy_struct(cmd, &info, &info_size, useraddr);
> if (ret)
> return ret;
>
> - ret = ops->get_rxnfc(dev, &info, NULL);
> - if (ret < 0)
> - return ret;
> + if (WARN_ON_ONCE(info.cmd != ETHTOOL_GRXRINGS))
> + return -EOPNOTSUPP;
I think malicious user space can trigger this warning with a TOCTOU
race. Let's skip the check, it's not really needed?
> + info.data = get_num_rxrings(dev);
