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From: Alexander Aring <aring@mojatatu.com>
Date: Thu, 18 Jan 2018 11:20:50 -0500
Subject: net: sched: cls_api: handle generic cls errors
Patch-mainline: v4.16-rc1
Git-commit: c35a4acc298528ac7ac8d21284af7cad981aa79d
References: bsc#1109837

This patch adds extack support for generic cls handling. The extack
will be set deeper to each called function which is not part of netdev
core api.

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/cls_api.c |   52 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 41 insertions(+), 11 deletions(-)

--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -123,7 +123,8 @@ static inline u32 tcf_auto_prio(struct t
 }
 
 static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol,
-					  u32 prio, struct tcf_chain *chain)
+					  u32 prio, struct tcf_chain *chain,
+					  struct netlink_ext_ack *extack)
 {
 	struct tcf_proto *tp;
 	int err;
@@ -149,6 +150,7 @@ static struct tcf_proto *tcf_proto_creat
 			module_put(tp->ops->owner);
 			err = -EAGAIN;
 		} else {
+			NL_SET_ERR_MSG(extack, "TC classifier not found");
 			err = -ENOENT;
 		}
 		goto errout;
@@ -935,7 +937,8 @@ static int tfilter_notify(struct net *ne
 static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
 			      struct nlmsghdr *n, struct tcf_proto *tp,
 			      struct tcf_block *block, struct Qdisc *q,
-			      u32 parent, void *fh, bool unicast, bool *last)
+			      u32 parent, void *fh, bool unicast, bool *last,
+			      struct netlink_ext_ack *extack)
 {
 	struct sk_buff *skb;
 	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
@@ -947,6 +950,7 @@ static int tfilter_del_notify(struct net
 
 	if (tcf_fill_node(net, skb, tp, block, q, parent, fh, portid,
 			  n->nlmsg_seq, n->nlmsg_flags, RTM_DELTFILTER) <= 0) {
+		NL_SET_ERR_MSG(extack, "Failed to build del event notification");
 		kfree_skb(skb);
 		return -EINVAL;
 	}
@@ -960,8 +964,11 @@ static int tfilter_del_notify(struct net
 	if (unicast)
 		return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
 
-	return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
-			      n->nlmsg_flags & NLM_F_ECHO);
+	err = rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+			     n->nlmsg_flags & NLM_F_ECHO);
+	if (err < 0)
+		NL_SET_ERR_MSG(extack, "Failed to send filter delete notification");
+	return err;
 }
 
 static void tfilter_notify_chain(struct net *net, struct sk_buff *oskb,
@@ -1021,8 +1028,10 @@ replay:
 	if (prio == 0) {
 		switch (n->nlmsg_type) {
 		case RTM_DELTFILTER:
-			if (protocol || t->tcm_handle || tca[TCA_KIND])
+			if (protocol || t->tcm_handle || tca[TCA_KIND]) {
+				NL_SET_ERR_MSG(extack, "Cannot flush filters with protocol, handle or kind set");
 				return -ENOENT;
+			}
 			break;
 		case RTM_NEWTFILTER:
 			/* If no priority is provided by the user,
@@ -1035,6 +1044,7 @@ replay:
 			}
 			/* fall-through */
 		default:
+			NL_SET_ERR_MSG(extack, "Invalid filter command with priority of zero");
 			return -ENOENT;
 		}
 	}
@@ -1063,23 +1073,31 @@ replay:
 			parent = q->handle;
 		} else {
 			q = qdisc_lookup(dev, TC_H_MAJ(t->tcm_parent));
-			if (!q)
+			if (!q) {
+				NL_SET_ERR_MSG(extack, "Parent Qdisc doesn't exists");
 				return -EINVAL;
+			}
 		}
 
 		/* Is it classful? */
 		cops = q->ops->cl_ops;
-		if (!cops)
+		if (!cops) {
+			NL_SET_ERR_MSG(extack, "Qdisc not classful");
 			return -EINVAL;
+		}
 
-		if (!cops->tcf_block)
+		if (!cops->tcf_block) {
+			NL_SET_ERR_MSG(extack, "Class doesn't support blocks");
 			return -EOPNOTSUPP;
+		}
 
 		/* Do we search for filter, attached to class? */
 		if (TC_H_MIN(parent)) {
 			cl = cops->find(q, parent);
-			if (cl == 0)
+			if (cl == 0) {
+				NL_SET_ERR_MSG(extack, "Specified class doesn't exist");
 				return -ENOENT;
+			}
 		}
 
 		/* And the last stroke */
@@ -1097,12 +1115,14 @@ replay:
 
 	chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
 	if (chain_index > TC_ACT_EXT_VAL_MASK) {
+		NL_SET_ERR_MSG(extack, "Specified chain index exceeds upper limit");
 		err = -EINVAL;
 		goto errout;
 	}
 	chain = tcf_chain_get(block, chain_index,
 			      n->nlmsg_type == RTM_NEWTFILTER);
 	if (!chain) {
+		NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
 		err = n->nlmsg_type == RTM_NEWTFILTER ? -ENOMEM : -EINVAL;
 		goto errout;
 	}
@@ -1118,6 +1138,7 @@ replay:
 	tp = tcf_chain_tp_find(chain, &chain_info, protocol,
 			       prio, prio_allocate);
 	if (IS_ERR(tp)) {
+		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");
 		err = PTR_ERR(tp);
 		goto errout;
 	}
@@ -1126,12 +1147,14 @@ replay:
 		/* Proto-tcf does not exist, create new one */
 
 		if (tca[TCA_KIND] == NULL || !protocol) {
+			NL_SET_ERR_MSG(extack, "Filter kind and protocol must be specified");
 			err = -EINVAL;
 			goto errout;
 		}
 
 		if (n->nlmsg_type != RTM_NEWTFILTER ||
 		    !(n->nlmsg_flags & NLM_F_CREATE)) {
+			NL_SET_ERR_MSG(extack, "Need both RTM_NEWTFILTER and NLM_F_CREATE to create a new filter");
 			err = -ENOENT;
 			goto errout;
 		}
@@ -1140,13 +1163,14 @@ replay:
 			prio = tcf_auto_prio(tcf_chain_tp_prev(&chain_info));
 
 		tp = tcf_proto_create(nla_data(tca[TCA_KIND]),
-				      protocol, prio, chain);
+				      protocol, prio, chain, extack);
 		if (IS_ERR(tp)) {
 			err = PTR_ERR(tp);
 			goto errout;
 		}
 		tp_created = 1;
 	} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {
+		NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
 		err = -EINVAL;
 		goto errout;
 	}
@@ -1165,6 +1189,7 @@ replay:
 
 		if (n->nlmsg_type != RTM_NEWTFILTER ||
 		    !(n->nlmsg_flags & NLM_F_CREATE)) {
+			NL_SET_ERR_MSG(extack, "Need both RTM_NEWTFILTER and NLM_F_CREATE to create a new filter");
 			err = -ENOENT;
 			goto errout;
 		}
@@ -1176,13 +1201,15 @@ replay:
 			if (n->nlmsg_flags & NLM_F_EXCL) {
 				if (tp_created)
 					tcf_proto_destroy(tp);
+				NL_SET_ERR_MSG(extack, "Filter already exists");
 				err = -EEXIST;
 				goto errout;
 			}
 			break;
 		case RTM_DELTFILTER:
 			err = tfilter_del_notify(net, skb, n, tp, block,
-						 q, parent, fh, false, &last);
+						 q, parent, fh, false, &last,
+						 extack);
 			if (err)
 				goto errout;
 			if (last) {
@@ -1193,8 +1220,11 @@ replay:
 		case RTM_GETTFILTER:
 			err = tfilter_notify(net, skb, n, tp, block, q, parent,
 					     fh, RTM_NEWTFILTER, true);
+			if (err < 0)
+				NL_SET_ERR_MSG(extack, "Failed to send filter notify message");
 			goto errout;
 		default:
+			NL_SET_ERR_MSG(extack, "Invalid netlink message type");
 			err = -EINVAL;
 			goto errout;
 		}