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 <dsah...@gmail.com>
Signed-off-by: Alexander Aring <ar...@mojatatu.com>
---
 net/sched/cls_api.c | 55 +++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 12 deletions(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 01d09055707d..c25a9b4bcb4b 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -122,7 +122,8 @@ static inline u32 tcf_auto_prio(struct tcf_proto *tp)
 
 static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol,
                                          u32 prio, u32 parent, struct Qdisc *q,
-                                         struct tcf_chain *chain)
+                                         struct tcf_chain *chain,
+                                         struct netlink_ext_ack *extack)
 {
        struct tcf_proto *tp;
        int err;
@@ -148,6 +149,7 @@ static struct tcf_proto *tcf_proto_create(const char *kind, 
u32 protocol,
                        module_put(tp->ops->owner);
                        err = -EAGAIN;
                } else {
+                       NL_SET_ERR_MSG(extack, "TC classifier not found");
                        err = -ENOENT;
                }
                goto errout;
@@ -662,7 +664,8 @@ static int tfilter_notify(struct net *net, struct sk_buff 
*oskb,
 static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
                              struct nlmsghdr *n, struct tcf_proto *tp,
                              struct Qdisc *q, u32 parent,
-                             void *fh, bool unicast, bool *last)
+                             void *fh, bool unicast, bool *last,
+                             struct netlink_ext_ack *extack)
 {
        struct sk_buff *skb;
        u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
@@ -674,6 +677,7 @@ static int tfilter_del_notify(struct net *net, struct 
sk_buff *oskb,
 
        if (tcf_fill_node(net, skb, tp, 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;
        }
@@ -687,8 +691,11 @@ static int tfilter_del_notify(struct net *net, struct 
sk_buff *oskb,
        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,
@@ -749,8 +756,10 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
        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,
@@ -763,6 +772,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
                        }
                        /* fall-through */
                default:
+                       NL_SET_ERR_MSG(extack, "Invalid filter command with 
priority of zero");
                        return -ENOENT;
                }
        }
@@ -780,23 +790,31 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
                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 */
@@ -808,12 +826,14 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
 
        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;
        }
@@ -829,6 +849,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
        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;
        }
@@ -837,12 +858,14 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
                /* 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;
                }
@@ -851,13 +874,14 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
                        prio = tcf_auto_prio(tcf_chain_tp_prev(&chain_info));
 
                tp = tcf_proto_create(nla_data(tca[TCA_KIND]),
-                                     protocol, prio, parent, q, chain);
+                                     protocol, prio, parent, q, 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;
        }
@@ -876,6 +900,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
 
                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;
                }
@@ -887,13 +912,14 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
                        if (n->nlmsg_flags & NLM_F_EXCL) {
                                if (tp_created)
                                        tcf_proto_destroy(tp);
+                               NL_SET_ERR_MSG(extack, "Exclusivity check 
success. Filter already exists");
                                err = -EEXIST;
                                goto errout;
                        }
                        break;
                case RTM_DELTFILTER:
                        err = tfilter_del_notify(net, skb, n, tp, q, parent,
-                                                fh, false, &last);
+                                                fh, false, &last, extack);
                        if (err)
                                goto errout;
                        if (last) {
@@ -904,8 +930,11 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
                case RTM_GETTFILTER:
                        err = tfilter_notify(net, skb, n, tp, 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;
                }
@@ -1117,8 +1146,10 @@ int tcf_exts_validate(struct net *net, struct tcf_proto 
*tp, struct nlattr **tb,
        }
 #else
        if ((exts->action && tb[exts->action]) ||
-           (exts->police && tb[exts->police]))
+           (exts->police && tb[exts->police])) {
+               NL_SET_ERR_MSG(extack, "Actions are not supported. Check 
compile options");
                return -EOPNOTSUPP;
+       }
 #endif
 
        return 0;
-- 
2.11.0

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