net: sched: Support specifying a starting chain via tc skb ext

Set the starting chain from the tc skb ext chain value. Once we read
the tc skb ext, delete it, so cloned/redirect packets won't inherit it.

In order to lookup a chain by the chain index on the ingress block
at ingress classification, provide a lookup function.

Co-developed-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index a634c85..e604ebe 100644 (file)
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -454,6 +454,20 @@ static struct tcf_chain *tcf_chain_lookup(struct tcf_block *block,
        return NULL;
 }
 
+#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
+static struct tcf_chain *tcf_chain_lookup_rcu(const struct tcf_block *block,
+                                             u32 chain_index)
+{
+       struct tcf_chain *chain;
+
+       list_for_each_entry_rcu(chain, &block->chain_list, list) {
+               if (chain->index == chain_index)
+                       return chain;
+       }
+       return NULL;
+}
+#endif
+
 static int tc_chain_notify(struct tcf_chain *chain, struct sk_buff *oskb,
                           u32 seq, u16 flags, int event, bool unicast);
 
@@ -1562,13 +1576,13 @@ static int tcf_block_setup(struct tcf_block *block,
  */
 static inline int __tcf_classify(struct sk_buff *skb,
                                 const struct tcf_proto *tp,
+                                const struct tcf_proto *orig_tp,
                                 struct tcf_result *res,
                                 bool compat_mode,
                                 u32 *last_executed_chain)
 {
 #ifdef CONFIG_NET_CLS_ACT
        const int max_reclassify_loop = 4;
-       const struct tcf_proto *orig_tp = tp;
        const struct tcf_proto *first_tp;
        int limit = 0;
 
@@ -1619,7 +1633,7 @@ int tcf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 {
        u32 last_executed_chain = 0;
 
-       return __tcf_classify(skb, tp, res, compat_mode,
+       return __tcf_classify(skb, tp, tp, res, compat_mode,
                              &last_executed_chain);
 }
 EXPORT_SYMBOL(tcf_classify);
@@ -1632,14 +1646,31 @@ int tcf_classify_ingress(struct sk_buff *skb,
 #if !IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
        u32 last_executed_chain = 0;
 
-       return __tcf_classify(skb, tp, res, compat_mode,
+       return __tcf_classify(skb, tp, tp, res, compat_mode,
                              &last_executed_chain);
 #else
        u32 last_executed_chain = tp ? tp->chain->index : 0;
+       const struct tcf_proto *orig_tp = tp;
        struct tc_skb_ext *ext;
        int ret;
 
-       ret = __tcf_classify(skb, tp, res, compat_mode, &last_executed_chain);
+       ext = skb_ext_find(skb, TC_SKB_EXT);
+
+       if (ext && ext->chain) {
+               struct tcf_chain *fchain;
+
+               fchain = tcf_chain_lookup_rcu(ingress_block, ext->chain);
+               if (!fchain)
+                       return TC_ACT_SHOT;
+
+               /* Consume, so cloned/redirect skbs won't inherit ext */
+               skb_ext_del(skb, TC_SKB_EXT);
+
+               tp = rcu_dereference_bh(fchain->filter_chain);
+       }
+
+       ret = __tcf_classify(skb, tp, orig_tp, res, compat_mode,
+                            &last_executed_chain);
 
        /* If we missed on some chain */
        if (ret == TC_ACT_UNSPEC && last_executed_chain) {