ethtool: rss: support setting hkey via Netlink

Support setting RSS hashing key via ethtool Netlink.
Use the Netlink policy to make sure user doesn't pass
an empty key, "resetting" the key is not a thing.

Reviewed-by: Gal Pressman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

Documentation/netlink/specs/ethtool.yaml

@@ -2656,6 +2656,7 @@ operations:
             - context
             - hfunc
             - indir
+            - hkey
     -
       name: rss-ntf
       doc: |

Documentation/networking/ethtool-netlink.rst

@@ -2001,6 +2001,7 @@ Request contents:
   ``ETHTOOL_A_RSS_CONTEXT``            u32     context number
   ``ETHTOOL_A_RSS_HFUNC``              u32     RSS hash func
   ``ETHTOOL_A_RSS_INDIR``              binary  Indir table bytes
+  ``ETHTOOL_A_RSS_HKEY``               binary  Hash key bytes
 =====================================  ======  ==============================
 
 ``ETHTOOL_A_RSS_INDIR`` is the minimal RSS table the user expects. Kernel and

net/ethtool/rss.c

@@ -477,6 +477,7 @@ const struct nla_policy ethnl_rss_set_policy[ETHTOOL_A_RSS_START_CONTEXT + 1] =
 	[ETHTOOL_A_RSS_CONTEXT] = { .type = NLA_U32, },
 	[ETHTOOL_A_RSS_HFUNC] = NLA_POLICY_MIN(NLA_U32, 1),
 	[ETHTOOL_A_RSS_INDIR] = { .type = NLA_BINARY, },
+	[ETHTOOL_A_RSS_HKEY] = NLA_POLICY_MIN(NLA_BINARY, 1),
 };
 
 static int
@@ -490,8 +491,10 @@ ethnl_rss_set_validate(struct ethnl_req_info *req_info, struct genl_info *info)
 	if (request->rss_context && !ops->create_rxfh_context)
 		bad_attr = bad_attr ?: tb[ETHTOOL_A_RSS_CONTEXT];
 
-	if (request->rss_context && !ops->rxfh_per_ctx_key)
+	if (request->rss_context && !ops->rxfh_per_ctx_key) {
 		bad_attr = bad_attr ?: tb[ETHTOOL_A_RSS_HFUNC];
+		bad_attr = bad_attr ?: tb[ETHTOOL_A_RSS_HKEY];
+	}
 
 	if (bad_attr) {
 		NL_SET_BAD_ATTR(info->extack, bad_attr);
@@ -581,6 +584,31 @@ rss_set_prep_indir(struct net_device *dev, struct genl_info *info,
 	return err;
 }
 
+static int
+rss_set_prep_hkey(struct net_device *dev, struct genl_info *info,
+		  struct rss_reply_data *data, struct ethtool_rxfh_param *rxfh,
+		  bool *mod)
+{
+	struct nlattr **tb = info->attrs;
+
+	if (!tb[ETHTOOL_A_RSS_HKEY])
+		return 0;
+
+	if (nla_len(tb[ETHTOOL_A_RSS_HKEY]) != data->hkey_size) {
+		NL_SET_BAD_ATTR(info->extack, tb[ETHTOOL_A_RSS_HKEY]);
+		return -EINVAL;
+	}
+
+	rxfh->key_size = data->hkey_size;
+	rxfh->key = kmemdup(data->hkey, data->hkey_size, GFP_KERNEL);
+	if (!rxfh->key)
+		return -ENOMEM;
+
+	ethnl_update_binary(rxfh->key, rxfh->key_size, tb[ETHTOOL_A_RSS_HKEY],
+			    mod);
+	return 0;
+}
+
 static void
 rss_set_ctx_update(struct ethtool_rxfh_context *ctx, struct nlattr **tb,
 		   struct rss_reply_data *data, struct ethtool_rxfh_param *rxfh)
@@ -592,6 +620,11 @@ rss_set_ctx_update(struct ethtool_rxfh_context *ctx, struct nlattr **tb,
 			ethtool_rxfh_context_indir(ctx)[i] = rxfh->indir[i];
 		ctx->indir_configured = !!nla_len(tb[ETHTOOL_A_RSS_INDIR]);
 	}
+	if (rxfh->key) {
+		memcpy(ethtool_rxfh_context_key(ctx), rxfh->key,
+		       data->hkey_size);
+		ctx->key_configured = !!rxfh->key_size;
+	}
 	if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE)
 		ctx->hfunc = rxfh->hfunc;
 }
@@ -629,6 +662,10 @@ ethnl_rss_set(struct ethnl_req_info *req_info, struct genl_info *info)
 	if (rxfh.hfunc == data.hfunc)
 		rxfh.hfunc = ETH_RSS_HASH_NO_CHANGE;
 
+	ret = rss_set_prep_hkey(dev, info, &data, &rxfh, &mod);
+	if (ret)
+		goto exit_free_indir;
+
 	rxfh.input_xfrm = RXH_XFRM_NO_CHANGE;
 
 	mutex_lock(&dev->ethtool->rss_lock);
@@ -660,6 +697,8 @@ ethnl_rss_set(struct ethnl_req_info *req_info, struct genl_info *info)
 
 exit_unlock:
 	mutex_unlock(&dev->ethtool->rss_lock);
+	kfree(rxfh.key);
+exit_free_indir:
 	kfree(rxfh.indir);
 exit_clean_data:
 	rss_cleanup_data(&data.base);