Merge branch 'net-sched-act-add-extack-support'

Alexander Aring says:

====================
net: sched: act: add extack support

this patch series adds extack support for the TC action subsystem.
As example I for the extack support in a TC action I choosed mirred
action.

- Alex

Cc: David Ahern <dsahern@gmail.com>

changes since v3:
- adapt recommended changes from Davide Caratti, please check if
  I catch everything. Thanks.

changes since v2:

- remove newline in extack of generic walker handling
  Thanks to Davide Caratti
- add kernel@mojatatu.com in cc
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/act_api.h

@@ -87,12 +87,15 @@ struct tc_action_ops {
 		       struct tcf_result *);
 	int     (*dump)(struct sk_buff *, struct tc_action *, int, int);
 	void	(*cleanup)(struct tc_action *);
-	int     (*lookup)(struct net *, struct tc_action **, u32);
+	int     (*lookup)(struct net *net, struct tc_action **a, u32 index,
+			  struct netlink_ext_ack *extack);
 	int     (*init)(struct net *net, struct nlattr *nla,
 			struct nlattr *est, struct tc_action **act, int ovr,
-			int bind);
+			int bind, struct netlink_ext_ack *extack);
 	int     (*walk)(struct net *, struct sk_buff *,
-			struct netlink_callback *, int, const struct tc_action_ops *);
+			struct netlink_callback *, int,
+			const struct tc_action_ops *,
+			struct netlink_ext_ack *);
 	void	(*stats_update)(struct tc_action *, u64, u32, u64);
 	struct net_device *(*get_dev)(const struct tc_action *a);
 };
@@ -137,7 +140,8 @@ static inline void tc_action_net_exit(struct list_head *net_list,
 
 int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb,
 		       struct netlink_callback *cb, int type,
-		       const struct tc_action_ops *ops);
+		       const struct tc_action_ops *ops,
+		       struct netlink_ext_ack *extack);
 int tcf_idr_search(struct tc_action_net *tn, struct tc_action **a, u32 index);
 bool tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a,
 		    int bind);
@@ -162,10 +166,11 @@ int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions,
 		    int nr_actions, struct tcf_result *res);
 int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,
 		    struct nlattr *est, char *name, int ovr, int bind,
-		    struct list_head *actions);
+		    struct list_head *actions, struct netlink_ext_ack *extack);
 struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 				    struct nlattr *nla, struct nlattr *est,
-				    char *name, int ovr, int bind);
+				    char *name, int ovr, int bind,
+				    struct netlink_ext_ack *extack);
 int tcf_action_dump(struct sk_buff *skb, struct list_head *, int, int);
 int tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int, int);
 int tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int, int);

net/sched/act_api.c

@@ -202,7 +202,8 @@ nla_put_failure:
 
 int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb,
 		       struct netlink_callback *cb, int type,
-		       const struct tc_action_ops *ops)
+		       const struct tc_action_ops *ops,
+		       struct netlink_ext_ack *extack)
 {
 	struct tcf_idrinfo *idrinfo = tn->idrinfo;
 
@@ -211,7 +212,8 @@ int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb,
 	} else if (type == RTM_GETACTION) {
 		return tcf_dump_walker(idrinfo, skb, cb);
 	} else {
-		WARN(1, "tcf_generic_walker: unknown action %d\n", type);
+		WARN(1, "tcf_generic_walker: unknown command %d\n", type);
+		NL_SET_ERR_MSG(extack, "tcf_generic_walker: unknown command");
 		return -EINVAL;
 	}
 }
@@ -605,7 +607,8 @@ static struct tc_cookie *nla_memdup_cookie(struct nlattr **tb)
 
 struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 				    struct nlattr *nla, struct nlattr *est,
-				    char *name, int ovr, int bind)
+				    char *name, int ovr, int bind,
+				    struct netlink_ext_ack *extack)
 {
 	struct tc_action *a;
 	struct tc_action_ops *a_o;
@@ -616,31 +619,40 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 	int err;
 
 	if (name == NULL) {
-		err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL, NULL);
+		err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL, extack);
 		if (err < 0)
 			goto err_out;
 		err = -EINVAL;
 		kind = tb[TCA_ACT_KIND];
-		if (kind == NULL)
+		if (!kind) {
+			NL_SET_ERR_MSG(extack, "TC action kind must be specified");
 			goto err_out;
-		if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ)
+		}
+		if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ) {
+			NL_SET_ERR_MSG(extack, "TC action name too long");
 			goto err_out;
+		}
 		if (tb[TCA_ACT_COOKIE]) {
 			int cklen = nla_len(tb[TCA_ACT_COOKIE]);
 
-			if (cklen > TC_COOKIE_MAX_SIZE)
+			if (cklen > TC_COOKIE_MAX_SIZE) {
+				NL_SET_ERR_MSG(extack, "TC cookie size above the maximum");
 				goto err_out;
+			}
 
 			cookie = nla_memdup_cookie(tb);
 			if (!cookie) {
+				NL_SET_ERR_MSG(extack, "No memory to generate TC cookie");
 				err = -ENOMEM;
 				goto err_out;
 			}
 		}
 	} else {
-		err = -EINVAL;
-		if (strlcpy(act_name, name, IFNAMSIZ) >= IFNAMSIZ)
+		if (strlcpy(act_name, name, IFNAMSIZ) >= IFNAMSIZ) {
+			NL_SET_ERR_MSG(extack, "TC action name too long");
+			err = -EINVAL;
 			goto err_out;
+		}
 	}
 
 	a_o = tc_lookup_action_n(act_name);
@@ -663,15 +675,17 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 			goto err_mod;
 		}
 #endif
+		NL_SET_ERR_MSG(extack, "Failed to load TC action module");
 		err = -ENOENT;
 		goto err_out;
 	}
 
 	/* backward compatibility for policer */
 	if (name == NULL)
-		err = a_o->init(net, tb[TCA_ACT_OPTIONS], est, &a, ovr, bind);
+		err = a_o->init(net, tb[TCA_ACT_OPTIONS], est, &a, ovr, bind,
+				extack);
 	else
-		err = a_o->init(net, nla, est, &a, ovr, bind);
+		err = a_o->init(net, nla, est, &a, ovr, bind, extack);
 	if (err < 0)
 		goto err_mod;
 
@@ -697,6 +711,7 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 
 			list_add_tail(&a->list, &actions);
 			tcf_action_destroy(&actions, bind);
+			NL_SET_ERR_MSG(extack, "Failed to init TC action chain");
 			return ERR_PTR(err);
 		}
 	}
@@ -726,19 +741,20 @@ static void cleanup_a(struct list_head *actions, int ovr)
 
 int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,
 		    struct nlattr *est, char *name, int ovr, int bind,
-		    struct list_head *actions)
+		    struct list_head *actions, struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
 	struct tc_action *act;
 	int err;
 	int i;
 
-	err = nla_parse_nested(tb, TCA_ACT_MAX_PRIO, nla, NULL, NULL);
+	err = nla_parse_nested(tb, TCA_ACT_MAX_PRIO, nla, NULL, extack);
 	if (err < 0)
 		return err;
 
 	for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
-		act = tcf_action_init_1(net, tp, tb[i], est, name, ovr, bind);
+		act = tcf_action_init_1(net, tp, tb[i], est, name, ovr, bind,
+					extack);
 		if (IS_ERR(act)) {
 			err = PTR_ERR(act);
 			goto err;
@@ -822,7 +838,7 @@ static int tca_get_fill(struct sk_buff *skb, struct list_head *actions,
 	t->tca__pad2 = 0;
 
 	nest = nla_nest_start(skb, TCA_ACT_TAB);
-	if (nest == NULL)
+	if (!nest)
 		goto out_nlmsg_trim;
 
 	if (tcf_action_dump(skb, actions, bind, ref) < 0)
@@ -840,7 +856,8 @@ out_nlmsg_trim:
 
 static int
 tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,
-	       struct list_head *actions, int event)
+	       struct list_head *actions, int event,
+	       struct netlink_ext_ack *extack)
 {
 	struct sk_buff *skb;
 
@@ -849,6 +866,7 @@ tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,
 		return -ENOBUFS;
 	if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, event,
 			 0, 0) <= 0) {
+		NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while adding TC action");
 		kfree_skb(skb);
 		return -EINVAL;
 	}
@@ -857,7 +875,8 @@ tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,
 }
 
 static struct tc_action *tcf_action_get_1(struct net *net, struct nlattr *nla,
-					  struct nlmsghdr *n, u32 portid)
+					  struct nlmsghdr *n, u32 portid,
+					  struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[TCA_ACT_MAX + 1];
 	const struct tc_action_ops *ops;
@@ -865,22 +884,26 @@ static struct tc_action *tcf_action_get_1(struct net *net, struct nlattr *nla,
 	int index;
 	int err;
 
-	err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL, NULL);
+	err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL, extack);
 	if (err < 0)
 		goto err_out;
 
 	err = -EINVAL;
 	if (tb[TCA_ACT_INDEX] == NULL ||
-	    nla_len(tb[TCA_ACT_INDEX]) < sizeof(index))
+	    nla_len(tb[TCA_ACT_INDEX]) < sizeof(index)) {
+		NL_SET_ERR_MSG(extack, "Invalid TC action index value");
 		goto err_out;
+	}
 	index = nla_get_u32(tb[TCA_ACT_INDEX]);
 
 	err = -EINVAL;
 	ops = tc_lookup_action(tb[TCA_ACT_KIND]);
-	if (!ops) /* could happen in batch of actions */
+	if (!ops) { /* could happen in batch of actions */
+		NL_SET_ERR_MSG(extack, "Specified TC action not found");
 		goto err_out;
+	}
 	err = -ENOENT;
-	if (ops->lookup(net, &a, index) == 0)
+	if (ops->lookup(net, &a, index, extack) == 0)
 		goto err_mod;
 
 	module_put(ops->owner);
@@ -893,7 +916,8 @@ err_out:
 }
 
 static int tca_action_flush(struct net *net, struct nlattr *nla,
-			    struct nlmsghdr *n, u32 portid)
+			    struct nlmsghdr *n, u32 portid,
+			    struct netlink_ext_ack *extack)
 {
 	struct sk_buff *skb;
 	unsigned char *b;
@@ -907,37 +931,41 @@ static int tca_action_flush(struct net *net, struct nlattr *nla,
 	int err = -ENOMEM;
 
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
-	if (!skb) {
-		pr_debug("tca_action_flush: failed skb alloc\n");
+	if (!skb)
 		return err;
-	}
 
 	b = skb_tail_pointer(skb);
 
-	err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL, NULL);
+	err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL, extack);
 	if (err < 0)
 		goto err_out;
 
 	err = -EINVAL;
 	kind = tb[TCA_ACT_KIND];
 	ops = tc_lookup_action(kind);
-	if (!ops) /*some idjot trying to flush unknown action */
+	if (!ops) { /*some idjot trying to flush unknown action */
+		NL_SET_ERR_MSG(extack, "Cannot flush unknown TC action");
 		goto err_out;
+	}
 
 	nlh = nlmsg_put(skb, portid, n->nlmsg_seq, RTM_DELACTION,
 			sizeof(*t), 0);
-	if (!nlh)
+	if (!nlh) {
+		NL_SET_ERR_MSG(extack, "Failed to create TC action flush notification");
 		goto out_module_put;
+	}
 	t = nlmsg_data(nlh);
 	t->tca_family = AF_UNSPEC;
 	t->tca__pad1 = 0;
 	t->tca__pad2 = 0;
 
 	nest = nla_nest_start(skb, TCA_ACT_TAB);
-	if (nest == NULL)
+	if (!nest) {
+		NL_SET_ERR_MSG(extack, "Failed to add new netlink message");
 		goto out_module_put;
+	}
 
-	err = ops->walk(net, skb, &dcb, RTM_DELACTION, ops);
+	err = ops->walk(net, skb, &dcb, RTM_DELACTION, ops, extack);
 	if (err <= 0) {
 		nla_nest_cancel(skb, nest);
 		goto out_module_put;
@@ -952,6 +980,8 @@ static int tca_action_flush(struct net *net, struct nlattr *nla,
 			     n->nlmsg_flags & NLM_F_ECHO);
 	if (err > 0)
 		return 0;
+	if (err < 0)
+		NL_SET_ERR_MSG(extack, "Failed to send TC action flush notification");
 
 	return err;
 
@@ -964,7 +994,7 @@ err_out:
 
 static int
 tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
-	       u32 portid)
+	       u32 portid, struct netlink_ext_ack *extack)
 {
 	int ret;
 	struct sk_buff *skb;
@@ -975,6 +1005,7 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
 
 	if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, RTM_DELACTION,
 			 0, 1) <= 0) {
+		NL_SET_ERR_MSG(extack, "Failed to fill netlink TC action attributes");
 		kfree_skb(skb);
 		return -EINVAL;
 	}
@@ -982,6 +1013,7 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
 	/* now do the delete */
 	ret = tcf_action_destroy(actions, 0);
 	if (ret < 0) {
+		NL_SET_ERR_MSG(extack, "Failed to delete TC action");
 		kfree_skb(skb);
 		return ret;
 	}
@@ -995,26 +1027,27 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
 
 static int
 tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
-	      u32 portid, int event)
+	      u32 portid, int event, struct netlink_ext_ack *extack)
 {
 	int i, ret;
 	struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
 	struct tc_action *act;
 	LIST_HEAD(actions);
 
-	ret = nla_parse_nested(tb, TCA_ACT_MAX_PRIO, nla, NULL, NULL);
+	ret = nla_parse_nested(tb, TCA_ACT_MAX_PRIO, nla, NULL, extack);
 	if (ret < 0)
 		return ret;
 
 	if (event == RTM_DELACTION && n->nlmsg_flags & NLM_F_ROOT) {
-		if (tb[1] != NULL)
-			return tca_action_flush(net, tb[1], n, portid);
-		else
-			return -EINVAL;
+		if (tb[1])
+			return tca_action_flush(net, tb[1], n, portid, extack);
+
+		NL_SET_ERR_MSG(extack, "Invalid netlink attributes while flushing TC action");
+		return -EINVAL;
 	}
 
 	for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
-		act = tcf_action_get_1(net, tb[i], n, portid);
+		act = tcf_action_get_1(net, tb[i], n, portid, extack);
 		if (IS_ERR(act)) {
 			ret = PTR_ERR(act);
 			goto err;
@@ -1024,9 +1057,9 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
 	}
 
 	if (event == RTM_GETACTION)
-		ret = tcf_get_notify(net, portid, n, &actions, event);
+		ret = tcf_get_notify(net, portid, n, &actions, event, extack);
 	else { /* delete */
-		ret = tcf_del_notify(net, n, &actions, portid);
+		ret = tcf_del_notify(net, n, &actions, portid, extack);
 		if (ret)
 			goto err;
 		return ret;
@@ -1039,7 +1072,7 @@ err:
 
 static int
 tcf_add_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
-	       u32 portid)
+	       u32 portid, struct netlink_ext_ack *extack)
 {
 	struct sk_buff *skb;
 	int err = 0;
@@ -1050,6 +1083,7 @@ tcf_add_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
 
 	if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, n->nlmsg_flags,
 			 RTM_NEWACTION, 0, 0) <= 0) {
+		NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while deleting TC action");
 		kfree_skb(skb);
 		return -EINVAL;
 	}
@@ -1062,16 +1096,18 @@ tcf_add_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
 }
 
 static int tcf_action_add(struct net *net, struct nlattr *nla,
-			  struct nlmsghdr *n, u32 portid, int ovr)
+			  struct nlmsghdr *n, u32 portid, int ovr,
+			  struct netlink_ext_ack *extack)
 {
 	int ret = 0;
 	LIST_HEAD(actions);
 
-	ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, &actions);
+	ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, &actions,
+			      extack);
 	if (ret)
 		return ret;
 
-	return tcf_add_notify(net, n, &actions, portid);
+	return tcf_add_notify(net, n, &actions, portid, extack);
 }
 
 static u32 tcaa_root_flags_allowed = TCA_FLAG_LARGE_DUMP_ON;
@@ -1099,7 +1135,7 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 		return ret;
 
 	if (tca[TCA_ACT_TAB] == NULL) {
-		pr_notice("tc_ctl_action: received NO action attribs\n");
+		NL_SET_ERR_MSG(extack, "Netlink action attributes missing");
 		return -EINVAL;
 	}
 
@@ -1115,17 +1151,18 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 		if (n->nlmsg_flags & NLM_F_REPLACE)
 			ovr = 1;
 replay:
-		ret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, ovr);
+		ret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, ovr,
+				     extack);
 		if (ret == -EAGAIN)
 			goto replay;
 		break;
 	case RTM_DELACTION:
 		ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
-				    portid, RTM_DELACTION);
+				    portid, RTM_DELACTION, extack);
 		break;
 	case RTM_GETACTION:
 		ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
-				    portid, RTM_GETACTION);
+				    portid, RTM_GETACTION, extack);
 		break;
 	default:
 		BUG();
@@ -1220,7 +1257,7 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	if (nest == NULL)
 		goto out_module_put;
 
-	ret = a_o->walk(net, skb, cb, RTM_GETACTION, a_o);
+	ret = a_o->walk(net, skb, cb, RTM_GETACTION, a_o, NULL);
 	if (ret < 0)
 		goto out_module_put;
 

net/sched/act_bpf.c

@@ -272,7 +272,7 @@ static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 
 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 			struct nlattr *est, struct tc_action **act,
-			int replace, int bind)
+			int replace, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
 	struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
@@ -367,14 +367,16 @@ static void tcf_bpf_cleanup(struct tc_action *act)
 
 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 			  struct netlink_callback *cb, int type,
-			  const struct tc_action_ops *ops)
+			  const struct tc_action_ops *ops,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
 

net/sched/act_connmark.c

@@ -96,7 +96,8 @@ static const struct nla_policy connmark_policy[TCA_CONNMARK_MAX + 1] = {
 
 static int tcf_connmark_init(struct net *net, struct nlattr *nla,
 			     struct nlattr *est, struct tc_action **a,
-			     int ovr, int bind)
+			     int ovr, int bind,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, connmark_net_id);
 	struct nlattr *tb[TCA_CONNMARK_MAX + 1];
@@ -176,14 +177,16 @@ nla_put_failure:
 
 static int tcf_connmark_walker(struct net *net, struct sk_buff *skb,
 			       struct netlink_callback *cb, int type,
-			       const struct tc_action_ops *ops)
+			       const struct tc_action_ops *ops,
+			       struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, connmark_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_connmark_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_connmark_search(struct net *net, struct tc_action **a, u32 index,
+			       struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, connmark_net_id);
 

net/sched/act_csum.c

@@ -46,7 +46,7 @@ static struct tc_action_ops act_csum_ops;
 
 static int tcf_csum_init(struct net *net, struct nlattr *nla,
 			 struct nlattr *est, struct tc_action **a, int ovr,
-			 int bind)
+			 int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, csum_net_id);
 	struct tcf_csum_params *params_old, *params_new;
@@ -631,14 +631,16 @@ static void tcf_csum_cleanup(struct tc_action *a)
 
 static int tcf_csum_walker(struct net *net, struct sk_buff *skb,
 			   struct netlink_callback *cb, int type,
-			   const struct tc_action_ops *ops)
+			   const struct tc_action_ops *ops,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, csum_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_csum_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_csum_search(struct net *net, struct tc_action **a, u32 index,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, csum_net_id);
 

net/sched/act_gact.c

@@ -56,7 +56,7 @@ static const struct nla_policy gact_policy[TCA_GACT_MAX + 1] = {
 
 static int tcf_gact_init(struct net *net, struct nlattr *nla,
 			 struct nlattr *est, struct tc_action **a,
-			 int ovr, int bind)
+			 int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, gact_net_id);
 	struct nlattr *tb[TCA_GACT_MAX + 1];
@@ -201,14 +201,16 @@ nla_put_failure:
 
 static int tcf_gact_walker(struct net *net, struct sk_buff *skb,
 			   struct netlink_callback *cb, int type,
-			   const struct tc_action_ops *ops)
+			   const struct tc_action_ops *ops,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, gact_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_gact_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_gact_search(struct net *net, struct tc_action **a, u32 index,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, gact_net_id);
 

net/sched/act_ife.c

@@ -447,7 +447,7 @@ static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb,
 
 static int tcf_ife_init(struct net *net, struct nlattr *nla,
 			struct nlattr *est, struct tc_action **a,
-			int ovr, int bind)
+			int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, ife_net_id);
 	struct nlattr *tb[TCA_IFE_MAX + 1];
@@ -824,14 +824,16 @@ static int tcf_ife_act(struct sk_buff *skb, const struct tc_action *a,
 
 static int tcf_ife_walker(struct net *net, struct sk_buff *skb,
 			  struct netlink_callback *cb, int type,
-			  const struct tc_action_ops *ops)
+			  const struct tc_action_ops *ops,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, ife_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_ife_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_ife_search(struct net *net, struct tc_action **a, u32 index,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, ife_net_id);
 

net/sched/act_ipt.c

@@ -193,7 +193,7 @@ err1:
 
 static int tcf_ipt_init(struct net *net, struct nlattr *nla,
 			struct nlattr *est, struct tc_action **a, int ovr,
-			int bind)
+			int bind, struct netlink_ext_ack *extack)
 {
 	return __tcf_ipt_init(net, ipt_net_id, nla, est, a, &act_ipt_ops, ovr,
 			      bind);
@@ -201,7 +201,7 @@ static int tcf_ipt_init(struct net *net, struct nlattr *nla,
 
 static int tcf_xt_init(struct net *net, struct nlattr *nla,
 		       struct nlattr *est, struct tc_action **a, int ovr,
-		       int bind)
+		       int bind, struct netlink_ext_ack *extack)
 {
 	return __tcf_ipt_init(net, xt_net_id, nla, est, a, &act_xt_ops, ovr,
 			      bind);
@@ -303,14 +303,16 @@ nla_put_failure:
 
 static int tcf_ipt_walker(struct net *net, struct sk_buff *skb,
 			  struct netlink_callback *cb, int type,
-			  const struct tc_action_ops *ops)
+			  const struct tc_action_ops *ops,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, ipt_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_ipt_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_ipt_search(struct net *net, struct tc_action **a, u32 index,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, ipt_net_id);
 
@@ -351,14 +353,16 @@ static struct pernet_operations ipt_net_ops = {
 
 static int tcf_xt_walker(struct net *net, struct sk_buff *skb,
 			 struct netlink_callback *cb, int type,
-			 const struct tc_action_ops *ops)
+			 const struct tc_action_ops *ops,
+			 struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, xt_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_xt_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_xt_search(struct net *net, struct tc_action **a, u32 index,
+			 struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, xt_net_id);
 

net/sched/act_mirred.c

@@ -69,7 +69,7 @@ static struct tc_action_ops act_mirred_ops;
 
 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 			   struct nlattr *est, struct tc_action **a, int ovr,
-			   int bind)
+			   int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
 	struct nlattr *tb[TCA_MIRRED_MAX + 1];
@@ -80,13 +80,17 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 	bool exists = false;
 	int ret;
 
-	if (nla == NULL)
+	if (!nla) {
+		NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
 		return -EINVAL;
-	ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL);
+	}
+	ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack);
 	if (ret < 0)
 		return ret;
-	if (tb[TCA_MIRRED_PARMS] == NULL)
+	if (!tb[TCA_MIRRED_PARMS]) {
+		NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
 		return -EINVAL;
+	}
 	parm = nla_data(tb[TCA_MIRRED_PARMS]);
 
 	exists = tcf_idr_check(tn, parm->index, a, bind);
@@ -102,6 +106,7 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 	default:
 		if (exists)
 			tcf_idr_release(*a, bind);
+		NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 		return -EINVAL;
 	}
 	if (parm->ifindex) {
@@ -117,8 +122,10 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
 	}
 
 	if (!exists) {
-		if (dev == NULL)
+		if (!dev) {
+			NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 			return -EINVAL;
+		}
 		ret = tcf_idr_create(tn, parm->index, est, a,
 				     &act_mirred_ops, bind, true);
 		if (ret)
@@ -265,14 +272,16 @@ nla_put_failure:
 
 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 			     struct netlink_callback *cb, int type,
-			     const struct tc_action_ops *ops)
+			     const struct tc_action_ops *ops,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, mirred_net_id);
 

net/sched/act_nat.c

@@ -37,7 +37,8 @@ static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
 };
 
 static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
-			struct tc_action **a, int ovr, int bind)
+			struct tc_action **a, int ovr, int bind,
+			struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, nat_net_id);
 	struct nlattr *tb[TCA_NAT_MAX + 1];
@@ -277,14 +278,16 @@ nla_put_failure:
 
 static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
 			  struct netlink_callback *cb, int type,
-			  const struct tc_action_ops *ops)
+			  const struct tc_action_ops *ops,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, nat_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index,
+			  struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, nat_net_id);
 

net/sched/act_pedit.c

@@ -132,7 +132,7 @@ static int tcf_pedit_key_ex_dump(struct sk_buff *skb,
 
 static int tcf_pedit_init(struct net *net, struct nlattr *nla,
 			  struct nlattr *est, struct tc_action **a,
-			  int ovr, int bind)
+			  int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
 	struct nlattr *tb[TCA_PEDIT_MAX + 1];
@@ -419,14 +419,16 @@ nla_put_failure:
 
 static int tcf_pedit_walker(struct net *net, struct sk_buff *skb,
 			    struct netlink_callback *cb, int type,
-			    const struct tc_action_ops *ops)
+			    const struct tc_action_ops *ops,
+			    struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_pedit_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_pedit_search(struct net *net, struct tc_action **a, u32 index,
+			    struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
 

net/sched/act_police.c

@@ -58,11 +58,12 @@ static struct tc_action_ops act_police_ops;
 
 static int tcf_act_police_walker(struct net *net, struct sk_buff *skb,
 				 struct netlink_callback *cb, int type,
-				 const struct tc_action_ops *ops)
+				 const struct tc_action_ops *ops,
+				 struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, police_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
 static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
@@ -74,7 +75,8 @@ static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
 
 static int tcf_act_police_init(struct net *net, struct nlattr *nla,
 			       struct nlattr *est, struct tc_action **a,
-			       int ovr, int bind)
+			       int ovr, int bind,
+			       struct netlink_ext_ack *extack)
 {
 	int ret = 0, err;
 	struct nlattr *tb[TCA_POLICE_MAX + 1];
@@ -304,7 +306,8 @@ nla_put_failure:
 	return -1;
 }
 
-static int tcf_police_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_police_search(struct net *net, struct tc_action **a, u32 index,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, police_net_id);
 

net/sched/act_sample.c

@@ -37,7 +37,7 @@ static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
 
 static int tcf_sample_init(struct net *net, struct nlattr *nla,
 			   struct nlattr *est, struct tc_action **a, int ovr,
-			   int bind)
+			   int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, sample_net_id);
 	struct nlattr *tb[TCA_SAMPLE_MAX + 1];
@@ -202,14 +202,16 @@ nla_put_failure:
 
 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 			     struct netlink_callback *cb, int type,
-			     const struct tc_action_ops *ops)
+			     const struct tc_action_ops *ops,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, sample_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, sample_net_id);
 

net/sched/act_simple.c

@@ -79,7 +79,7 @@ static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
 
 static int tcf_simp_init(struct net *net, struct nlattr *nla,
 			 struct nlattr *est, struct tc_action **a,
-			 int ovr, int bind)
+			 int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, simp_net_id);
 	struct nlattr *tb[TCA_DEF_MAX + 1];
@@ -170,14 +170,16 @@ nla_put_failure:
 
 static int tcf_simp_walker(struct net *net, struct sk_buff *skb,
 			   struct netlink_callback *cb, int type,
-			   const struct tc_action_ops *ops)
+			   const struct tc_action_ops *ops,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, simp_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_simp_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_simp_search(struct net *net, struct tc_action **a, u32 index,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, simp_net_id);
 

net/sched/act_skbedit.c

@@ -66,7 +66,7 @@ static const struct nla_policy skbedit_policy[TCA_SKBEDIT_MAX + 1] = {
 
 static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
 			    struct nlattr *est, struct tc_action **a,
-			    int ovr, int bind)
+			    int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbedit_net_id);
 	struct nlattr *tb[TCA_SKBEDIT_MAX + 1];
@@ -208,14 +208,16 @@ nla_put_failure:
 
 static int tcf_skbedit_walker(struct net *net, struct sk_buff *skb,
 			      struct netlink_callback *cb, int type,
-			      const struct tc_action_ops *ops)
+			      const struct tc_action_ops *ops,
+			      struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbedit_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_skbedit_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_skbedit_search(struct net *net, struct tc_action **a, u32 index,
+			      struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbedit_net_id);
 

net/sched/act_skbmod.c

@@ -84,7 +84,7 @@ static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
 
 static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
 			   struct nlattr *est, struct tc_action **a,
-			   int ovr, int bind)
+			   int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
 	struct nlattr *tb[TCA_SKBMOD_MAX + 1];
@@ -232,14 +232,16 @@ nla_put_failure:
 
 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb,
 			     struct netlink_callback *cb, int type,
-			     const struct tc_action_ops *ops)
+			     const struct tc_action_ops *ops,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
 

net/sched/act_tunnel_key.c

@@ -70,7 +70,7 @@ static const struct nla_policy tunnel_key_policy[TCA_TUNNEL_KEY_MAX + 1] = {
 
 static int tunnel_key_init(struct net *net, struct nlattr *nla,
 			   struct nlattr *est, struct tc_action **a,
-			   int ovr, int bind)
+			   int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, tunnel_key_net_id);
 	struct nlattr *tb[TCA_TUNNEL_KEY_MAX + 1];
@@ -291,14 +291,16 @@ nla_put_failure:
 
 static int tunnel_key_walker(struct net *net, struct sk_buff *skb,
 			     struct netlink_callback *cb, int type,
-			     const struct tc_action_ops *ops)
+			     const struct tc_action_ops *ops,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, tunnel_key_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tunnel_key_search(struct net *net, struct tc_action **a, u32 index)
+static int tunnel_key_search(struct net *net, struct tc_action **a, u32 index,
+			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, tunnel_key_net_id);
 

net/sched/act_vlan.c

@@ -109,7 +109,7 @@ static const struct nla_policy vlan_policy[TCA_VLAN_MAX + 1] = {
 
 static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 			 struct nlattr *est, struct tc_action **a,
-			 int ovr, int bind)
+			 int ovr, int bind, struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
 	struct nlattr *tb[TCA_VLAN_MAX + 1];
@@ -267,14 +267,16 @@ nla_put_failure:
 
 static int tcf_vlan_walker(struct net *net, struct sk_buff *skb,
 			   struct netlink_callback *cb, int type,
-			   const struct tc_action_ops *ops)
+			   const struct tc_action_ops *ops,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
 
-	return tcf_generic_walker(tn, skb, cb, type, ops);
+	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 }
 
-static int tcf_vlan_search(struct net *net, struct tc_action **a, u32 index)
+static int tcf_vlan_search(struct net *net, struct tc_action **a, u32 index,
+			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
 

net/sched/cls_api.c

@@ -1434,7 +1434,7 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb,
 		if (exts->police && tb[exts->police]) {
 			act = tcf_action_init_1(net, tp, tb[exts->police],
 						rate_tlv, "police", ovr,
-						TCA_ACT_BIND);
+						TCA_ACT_BIND, extack);
 			if (IS_ERR(act))
 				return PTR_ERR(act);
 
@@ -1447,7 +1447,7 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb,
 
 			err = tcf_action_init(net, tp, tb[exts->action],
 					      rate_tlv, NULL, ovr, TCA_ACT_BIND,
-					      &actions);
+					      &actions, extack);
 			if (err)
 				return err;
 			list_for_each_entry(act, &actions, list)