ethtool: netlink: always pass genl_info to .prepare_data

We had a number of bugs in the past because developers forgot
to fully test dumps, which pass NULL as info to .prepare_data.
.prepare_data implementations would try to access info->extack
leading to a null-deref.

Now that dumps and notifications can access struct genl_info
we can pass it in, and remove the info null checks.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> # pause
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20230814214723.2924989-11-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ethtool/channels.c

@@ -24,7 +24,7 @@ const struct nla_policy ethnl_channels_get_policy[] = {
 
 static int channels_prepare_data(const struct ethnl_req_info *req_base,
 				 struct ethnl_reply_data *reply_base,
-				 struct genl_info *info)
+				 const struct genl_info *info)
 {
 	struct channels_reply_data *data = CHANNELS_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/coalesce.c

@@ -59,10 +59,9 @@ const struct nla_policy ethnl_coalesce_get_policy[] = {
 
 static int coalesce_prepare_data(const struct ethnl_req_info *req_base,
 				 struct ethnl_reply_data *reply_base,
-				 struct genl_info *info)
+				 const struct genl_info *info)
 {
 	struct coalesce_reply_data *data = COALESCE_REPDATA(reply_base);
-	struct netlink_ext_ack *extack = info ? info->extack : NULL;
 	struct net_device *dev = reply_base->dev;
 	int ret;
 
@@ -73,7 +72,8 @@ static int coalesce_prepare_data(const struct ethnl_req_info *req_base,
 	if (ret < 0)
 		return ret;
 	ret = dev->ethtool_ops->get_coalesce(dev, &data->coalesce,
-					     &data->kernel_coalesce, extack);
+					     &data->kernel_coalesce,
+					     info->extack);
 	ethnl_ops_complete(dev);
 
 	return ret;

net/ethtool/debug.c

@@ -23,7 +23,7 @@ const struct nla_policy ethnl_debug_get_policy[] = {
 
 static int debug_prepare_data(const struct ethnl_req_info *req_base,
 			      struct ethnl_reply_data *reply_base,
-			      struct genl_info *info)
+			      const struct genl_info *info)
 {
 	struct debug_reply_data *data = DEBUG_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/eee.c

@@ -26,7 +26,7 @@ const struct nla_policy ethnl_eee_get_policy[] = {
 
 static int eee_prepare_data(const struct ethnl_req_info *req_base,
 			    struct ethnl_reply_data *reply_base,
-			    struct genl_info *info)
+			    const struct genl_info *info)
 {
 	struct eee_reply_data *data = EEE_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/eeprom.c

@@ -51,8 +51,7 @@ static int fallback_set_params(struct eeprom_req_info *request,
 }
 
 static int eeprom_fallback(struct eeprom_req_info *request,
-			   struct eeprom_reply_data *reply,
+			   struct eeprom_reply_data *reply)
-			   struct genl_info *info)
 {
 	struct net_device *dev = reply->base.dev;
 	struct ethtool_modinfo modinfo = {0};
@@ -103,7 +102,7 @@ static int get_module_eeprom_by_page(struct net_device *dev,
 
 static int eeprom_prepare_data(const struct ethnl_req_info *req_base,
 			       struct ethnl_reply_data *reply_base,
-			       struct genl_info *info)
+			       const struct genl_info *info)
 {
 	struct eeprom_reply_data *reply = MODULE_EEPROM_REPDATA(reply_base);
 	struct eeprom_req_info *request = MODULE_EEPROM_REQINFO(req_base);
@@ -124,7 +123,7 @@ static int eeprom_prepare_data(const struct ethnl_req_info *req_base,
 	if (ret)
 		goto err_free;
 
-	ret = get_module_eeprom_by_page(dev, &page_data, info ? info->extack : NULL);
+	ret = get_module_eeprom_by_page(dev, &page_data, info->extack);
 	if (ret < 0)
 		goto err_ops;
 
@@ -140,7 +139,7 @@ err_free:
 	kfree(page_data.data);
 
 	if (ret == -EOPNOTSUPP)
-		return eeprom_fallback(request, reply, info);
+		return eeprom_fallback(request, reply);
 	return ret;
 }
 

net/ethtool/features.c

@@ -35,7 +35,7 @@ static void ethnl_features_to_bitmap32(u32 *dest, netdev_features_t src)
 
 static int features_prepare_data(const struct ethnl_req_info *req_base,
 				 struct ethnl_reply_data *reply_base,
-				 struct genl_info *info)
+				 const struct genl_info *info)
 {
 	struct features_reply_data *data = FEATURES_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/fec.c

@@ -92,7 +92,7 @@ fec_stats_recalc(struct fec_stat_grp *grp, struct ethtool_fec_stat *stats)
 
 static int fec_prepare_data(const struct ethnl_req_info *req_base,
 			    struct ethnl_reply_data *reply_base,
-			    struct genl_info *info)
+			    const struct genl_info *info)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(active_fec_modes) = {};
 	struct fec_reply_data *data = FEC_REPDATA(reply_base);

net/ethtool/linkinfo.c

@@ -23,7 +23,7 @@ const struct nla_policy ethnl_linkinfo_get_policy[] = {
 
 static int linkinfo_prepare_data(const struct ethnl_req_info *req_base,
 				 struct ethnl_reply_data *reply_base,
-				 struct genl_info *info)
+				 const struct genl_info *info)
 {
 	struct linkinfo_reply_data *data = LINKINFO_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/linkmodes.c

@@ -27,7 +27,7 @@ const struct nla_policy ethnl_linkmodes_get_policy[] = {
 
 static int linkmodes_prepare_data(const struct ethnl_req_info *req_base,
 				  struct ethnl_reply_data *reply_base,
-				  struct genl_info *info)
+				  const struct genl_info *info)
 {
 	struct linkmodes_reply_data *data = LINKMODES_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/linkstate.c

@@ -81,7 +81,7 @@ static int linkstate_get_link_ext_state(struct net_device *dev,
 
 static int linkstate_prepare_data(const struct ethnl_req_info *req_base,
 				  struct ethnl_reply_data *reply_base,
-				  struct genl_info *info)
+				  const struct genl_info *info)
 {
 	struct linkstate_reply_data *data = LINKSTATE_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/mm.c

@@ -27,7 +27,7 @@ const struct nla_policy ethnl_mm_get_policy[ETHTOOL_A_MM_HEADER + 1] = {
 
 static int mm_prepare_data(const struct ethnl_req_info *req_base,
 			   struct ethnl_reply_data *reply_base,
-			   struct genl_info *info)
+			   const struct genl_info *info)
 {
 	struct mm_reply_data *data = MM_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/module.c

@@ -38,10 +38,9 @@ static int module_get_power_mode(struct net_device *dev,
 
 static int module_prepare_data(const struct ethnl_req_info *req_base,
 			       struct ethnl_reply_data *reply_base,
-			       struct genl_info *info)
+			       const struct genl_info *info)
 {
 	struct module_reply_data *data = MODULE_REPDATA(reply_base);
-	struct netlink_ext_ack *extack = info ? info->extack : NULL;
 	struct net_device *dev = reply_base->dev;
 	int ret;
 
@@ -49,7 +48,7 @@ static int module_prepare_data(const struct ethnl_req_info *req_base,
 	if (ret < 0)
 		return ret;
 
-	ret = module_get_power_mode(dev, data, extack);
+	ret = module_get_power_mode(dev, data, info->extack);
 	if (ret < 0)
 		goto out_complete;
 

net/ethtool/netlink.c

@@ -444,12 +444,12 @@ err_dev:
 
 static int ethnl_default_dump_one(struct sk_buff *skb, struct net_device *dev,
 				  const struct ethnl_dump_ctx *ctx,
-				  struct netlink_callback *cb)
+				  const struct genl_info *info)
 {
 	void *ehdr;
 	int ret;
 
-	ehdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
+	ehdr = genlmsg_put(skb, info->snd_portid, info->snd_seq,
 			   &ethtool_genl_family, NLM_F_MULTI,
 			   ctx->ops->reply_cmd);
 	if (!ehdr)
@@ -457,7 +457,7 @@ static int ethnl_default_dump_one(struct sk_buff *skb, struct net_device *dev,
 
 	ethnl_init_reply_data(ctx->reply_data, ctx->ops, dev);
 	rtnl_lock();
-	ret = ctx->ops->prepare_data(ctx->req_info, ctx->reply_data, NULL);
+	ret = ctx->ops->prepare_data(ctx->req_info, ctx->reply_data, info);
 	rtnl_unlock();
 	if (ret < 0)
 		goto out;
@@ -495,7 +495,7 @@ static int ethnl_default_dumpit(struct sk_buff *skb,
 		dev_hold(dev);
 		rtnl_unlock();
 
-		ret = ethnl_default_dump_one(skb, dev, ctx, cb);
+		ret = ethnl_default_dump_one(skb, dev, ctx, genl_info_dump(cb));
 
 		rtnl_lock();
 		dev_put(dev);
@@ -647,11 +647,14 @@ static void ethnl_default_notify(struct net_device *dev, unsigned int cmd,
 	struct ethnl_reply_data *reply_data;
 	const struct ethnl_request_ops *ops;
 	struct ethnl_req_info *req_info;
+	struct genl_info info;
 	struct sk_buff *skb;
 	void *reply_payload;
 	int reply_len;
 	int ret;
 
+	genl_info_init_ntf(&info, &ethtool_genl_family, cmd);
+
 	if (WARN_ONCE(cmd > ETHTOOL_MSG_KERNEL_MAX ||
 		      !ethnl_default_notify_ops[cmd],
 		      "unexpected notification type %u\n", cmd))
@@ -670,7 +673,7 @@ static void ethnl_default_notify(struct net_device *dev, unsigned int cmd,
 	req_info->flags |= ETHTOOL_FLAG_COMPACT_BITSETS;
 
 	ethnl_init_reply_data(reply_data, ops, dev);
-	ret = ops->prepare_data(req_info, reply_data, NULL);
+	ret = ops->prepare_data(req_info, reply_data, &info);
 	if (ret < 0)
 		goto err_cleanup;
 	ret = ops->reply_size(req_info, reply_data);

net/ethtool/netlink.h

@@ -355,7 +355,7 @@ struct ethnl_request_ops {
 			     struct netlink_ext_ack *extack);
 	int (*prepare_data)(const struct ethnl_req_info *req_info,
 			    struct ethnl_reply_data *reply_data,
-			    struct genl_info *info);
+			    const struct genl_info *info);
 	int (*reply_size)(const struct ethnl_req_info *req_info,
 			  const struct ethnl_reply_data *reply_data);
 	int (*fill_reply)(struct sk_buff *skb,

net/ethtool/pause.c

@@ -51,10 +51,9 @@ static int pause_parse_request(struct ethnl_req_info *req_base,
 
 static int pause_prepare_data(const struct ethnl_req_info *req_base,
 			      struct ethnl_reply_data *reply_base,
-			      struct genl_info *info)
+			      const struct genl_info *info)
 {
 	const struct pause_req_info *req_info = PAUSE_REQINFO(req_base);
-	struct netlink_ext_ack *extack = info ? info->extack : NULL;
 	struct pause_reply_data *data = PAUSE_REPDATA(reply_base);
 	enum ethtool_mac_stats_src src = req_info->src;
 	struct net_device *dev = reply_base->dev;
@@ -74,7 +73,7 @@ static int pause_prepare_data(const struct ethnl_req_info *req_base,
 	if ((src == ETHTOOL_MAC_STATS_SRC_EMAC ||
 	     src == ETHTOOL_MAC_STATS_SRC_PMAC) &&
 	    !__ethtool_dev_mm_supported(dev)) {
-		NL_SET_ERR_MSG_MOD(extack,
+		NL_SET_ERR_MSG_MOD(info->extack,
 				   "Device does not support MAC merge layer");
 		ethnl_ops_complete(dev);
 		return -EOPNOTSUPP;

net/ethtool/phc_vclocks.c

@@ -24,7 +24,7 @@ const struct nla_policy ethnl_phc_vclocks_get_policy[] = {
 
 static int phc_vclocks_prepare_data(const struct ethnl_req_info *req_base,
 				    struct ethnl_reply_data *reply_base,
-				    struct genl_info *info)
+				    const struct genl_info *info)
 {
 	struct phc_vclocks_reply_data *data = PHC_VCLOCKS_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/plca.c

@@ -40,7 +40,7 @@ const struct nla_policy ethnl_plca_get_cfg_policy[] = {
 
 static int plca_get_cfg_prepare_data(const struct ethnl_req_info *req_base,
 				     struct ethnl_reply_data *reply_base,
-				     struct genl_info *info)
+				     const struct genl_info *info)
 {
 	struct plca_reply_data *data = PLCA_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;
@@ -183,7 +183,7 @@ const struct nla_policy ethnl_plca_get_status_policy[] = {
 
 static int plca_get_status_prepare_data(const struct ethnl_req_info *req_base,
 					struct ethnl_reply_data *reply_base,
-					struct genl_info *info)
+					const struct genl_info *info)
 {
 	struct plca_reply_data *data = PLCA_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/privflags.c

@@ -57,7 +57,7 @@ static int ethnl_get_priv_flags_info(struct net_device *dev,
 
 static int privflags_prepare_data(const struct ethnl_req_info *req_base,
 				  struct ethnl_reply_data *reply_base,
-				  struct genl_info *info)
+				  const struct genl_info *info)
 {
 	struct privflags_reply_data *data = PRIVFLAGS_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/pse-pd.c

@@ -53,8 +53,8 @@ static int pse_get_pse_attributes(struct net_device *dev,
 }
 
 static int pse_prepare_data(const struct ethnl_req_info *req_base,
-			       struct ethnl_reply_data *reply_base,
+			    struct ethnl_reply_data *reply_base,
-			       struct genl_info *info)
+			    const struct genl_info *info)
 {
 	struct pse_reply_data *data = PSE_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;
@@ -64,7 +64,7 @@ static int pse_prepare_data(const struct ethnl_req_info *req_base,
 	if (ret < 0)
 		return ret;
 
-	ret = pse_get_pse_attributes(dev, info ? info->extack : NULL, data);
+	ret = pse_get_pse_attributes(dev, info->extack, data);
 
 	ethnl_ops_complete(dev);
 

net/ethtool/rings.c

@@ -24,10 +24,9 @@ const struct nla_policy ethnl_rings_get_policy[] = {
 
 static int rings_prepare_data(const struct ethnl_req_info *req_base,
 			      struct ethnl_reply_data *reply_base,
-			      struct genl_info *info)
+			      const struct genl_info *info)
 {
 	struct rings_reply_data *data = RINGS_REPDATA(reply_base);
-	struct netlink_ext_ack *extack = info ? info->extack : NULL;
 	struct net_device *dev = reply_base->dev;
 	int ret;
 
@@ -39,7 +38,7 @@ static int rings_prepare_data(const struct ethnl_req_info *req_base,
 	if (ret < 0)
 		return ret;
 	dev->ethtool_ops->get_ringparam(dev, &data->ringparam,
-					&data->kernel_ringparam, extack);
+					&data->kernel_ringparam, info->extack);
 	ethnl_ops_complete(dev);
 
 	return 0;

net/ethtool/rss.c

@@ -42,7 +42,8 @@ rss_parse_request(struct ethnl_req_info *req_info, struct nlattr **tb,
 
 static int
 rss_prepare_data(const struct ethnl_req_info *req_base,
-		 struct ethnl_reply_data *reply_base, struct genl_info *info)
+		 struct ethnl_reply_data *reply_base,
+		 const struct genl_info *info)
 {
 	struct rss_reply_data *data = RSS_REPDATA(reply_base);
 	struct rss_req_info *request = RSS_REQINFO(req_base);

net/ethtool/stats.c

@@ -114,10 +114,9 @@ static int stats_parse_request(struct ethnl_req_info *req_base,
 
 static int stats_prepare_data(const struct ethnl_req_info *req_base,
 			      struct ethnl_reply_data *reply_base,
-			      struct genl_info *info)
+			      const struct genl_info *info)
 {
 	const struct stats_req_info *req_info = STATS_REQINFO(req_base);
-	struct netlink_ext_ack *extack = info ? info->extack : NULL;
 	struct stats_reply_data *data = STATS_REPDATA(reply_base);
 	enum ethtool_mac_stats_src src = req_info->src;
 	struct net_device *dev = reply_base->dev;
@@ -130,7 +129,7 @@ static int stats_prepare_data(const struct ethnl_req_info *req_base,
 	if ((src == ETHTOOL_MAC_STATS_SRC_EMAC ||
 	     src == ETHTOOL_MAC_STATS_SRC_PMAC) &&
 	    !__ethtool_dev_mm_supported(dev)) {
-		NL_SET_ERR_MSG_MOD(extack,
+		NL_SET_ERR_MSG_MOD(info->extack,
 				   "Device does not support MAC merge layer");
 		ethnl_ops_complete(dev);
 		return -EOPNOTSUPP;

net/ethtool/strset.c

@@ -274,7 +274,7 @@ static int strset_prepare_set(struct strset_info *info, struct net_device *dev,
 
 static int strset_prepare_data(const struct ethnl_req_info *req_base,
 			       struct ethnl_reply_data *reply_base,
-			       struct genl_info *info)
+			       const struct genl_info *info)
 {
 	const struct strset_req_info *req_info = STRSET_REQINFO(req_base);
 	struct strset_reply_data *data = STRSET_REPDATA(reply_base);

net/ethtool/tsinfo.c

@@ -25,7 +25,7 @@ const struct nla_policy ethnl_tsinfo_get_policy[] = {
 
 static int tsinfo_prepare_data(const struct ethnl_req_info *req_base,
 			       struct ethnl_reply_data *reply_base,
-			       struct genl_info *info)
+			       const struct genl_info *info)
 {
 	struct tsinfo_reply_data *data = TSINFO_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;

net/ethtool/wol.c

@@ -24,7 +24,7 @@ const struct nla_policy ethnl_wol_get_policy[] = {
 
 static int wol_prepare_data(const struct ethnl_req_info *req_base,
 			    struct ethnl_reply_data *reply_base,
-			    struct genl_info *info)
+			    const struct genl_info *info)
 {
 	struct wol_reply_data *data = WOL_REPDATA(reply_base);
 	struct net_device *dev = reply_base->dev;
@@ -39,7 +39,8 @@ static int wol_prepare_data(const struct ethnl_req_info *req_base,
 	dev->ethtool_ops->get_wol(dev, &data->wol);
 	ethnl_ops_complete(dev);
 	/* do not include password in notifications */
-	data->show_sopass = info && (data->wol.supported & WAKE_MAGICSECURE);
+	data->show_sopass = !genl_info_is_ntf(info) &&
+		(data->wol.supported & WAKE_MAGICSECURE);
 
 	return 0;
 }