net: check for driver support in netmem TX

We should not enable netmem TX for drivers that don't declare support.

Check for driver netmem TX support during devmem TX binding and fail if
the driver does not have the functionality.

Check for driver support in validate_xmit_skb as well.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250508004830.4100853-9-almasrymina@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/core/dev.c b/net/core/dev.c
index c9013632296f2f0678a305a2db9be8e842bac2ed..33d5e95209cb41496f5c82423d01890fc9fe78df 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3896,12 +3896,42 @@ sw_checksum:
 }
 EXPORT_SYMBOL(skb_csum_hwoffload_help);
 
+static struct sk_buff *validate_xmit_unreadable_skb(struct sk_buff *skb,
+                                                   struct net_device *dev)
+{
+       struct skb_shared_info *shinfo;
+       struct net_iov *niov;
+
+       if (likely(skb_frags_readable(skb)))
+               goto out;
+
+       if (!dev->netmem_tx)
+               goto out_free;
+
+       shinfo = skb_shinfo(skb);
+
+       if (shinfo->nr_frags > 0) {
+               niov = netmem_to_net_iov(skb_frag_netmem(&shinfo->frags[0]));
+               if (net_is_devmem_iov(niov) &&
+                   net_devmem_iov_binding(niov)->dev != dev)
+                       goto out_free;
+       }
+
+out:
+       return skb;
+
+out_free:
+       kfree_skb(skb);
+       return NULL;
+}
+
 static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device *dev, bool *again)
 {
        netdev_features_t features;
 
-       if (!skb_frags_readable(skb))
-               goto out_kfree_skb;
+       skb = validate_xmit_unreadable_skb(skb, dev);
+       if (unlikely(!skb))
+               goto out_null;
 
        features = netif_skb_features(skb);
        skb = validate_xmit_vlan(skb, features);

diff --git a/net/core/devmem.h b/net/core/devmem.h
index 67168aae5e5b35da412a6190409f5acdd1d1004e..919e6ed28fdcdff901a76ccb11d3d523e15207fc 100644 (file)
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -229,6 +229,12 @@ net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
 {
        return NULL;
 }
+
+static inline struct net_devmem_dmabuf_binding *
+net_devmem_iov_binding(const struct net_iov *niov)
+{
+       return NULL;
+}
 #endif
 
 #endif /* _NET_DEVMEM_H */

diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 93ea57d96931a903e748df06faa85049cf32be99..cfcf1654d4fb2369582c219b9b3f83f2b775d393 100644 (file)
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -1013,6 +1013,13 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
                goto err_unlock_netdev;
        }
 
+       if (!netdev->netmem_tx) {
+               err = -EOPNOTSUPP;
+               NL_SET_ERR_MSG(info->extack,
+                              "Driver does not support netmem TX");
+               goto err_unlock_netdev;
+       }
+
        binding = net_devmem_bind_dmabuf(netdev, DMA_TO_DEVICE, dmabuf_fd,
                                         info->extack);
        if (IS_ERR(binding)) {