netfilter: nf_tables: Speed up selective rule dumps

If just a table name was given, nf_tables_dump_rules() continued over
the list of tables even after a match was found. The simple fix is to
exit the loop if it reached the bottom and ctx->table was not NULL.

When iterating over the table's chains, the same problem as above
existed. But worse than that, if a chain name was given the hash table
wasn't used to find the corresponding chain. Fix this by introducing a
helper function iterating over a chain's rules (and taking care of the
cb->args handling), then introduce a shortcut to it if a chain name was
given.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 42487d01a3eda2306f78fde4b45919e2e06e941a..200751a49745aaadb075e05cfdd97f940ae08b73 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2291,15 +2291,52 @@ struct nft_rule_dump_ctx {
        char *chain;
 };
 
+static int __nf_tables_dump_rules(struct sk_buff *skb,
+                                 unsigned int *idx,
+                                 struct netlink_callback *cb,
+                                 const struct nft_table *table,
+                                 const struct nft_chain *chain)
+{
+       struct net *net = sock_net(skb->sk);
+       unsigned int s_idx = cb->args[0];
+       const struct nft_rule *rule;
+       int rc = 1;
+
+       list_for_each_entry_rcu(rule, &chain->rules, list) {
+               if (!nft_is_active(net, rule))
+                       goto cont;
+               if (*idx < s_idx)
+                       goto cont;
+               if (*idx > s_idx) {
+                       memset(&cb->args[1], 0,
+                                       sizeof(cb->args) - sizeof(cb->args[0]));
+               }
+               if (nf_tables_fill_rule_info(skb, net, NETLINK_CB(cb->skb).portid,
+                                       cb->nlh->nlmsg_seq,
+                                       NFT_MSG_NEWRULE,
+                                       NLM_F_MULTI | NLM_F_APPEND,
+                                       table->family,
+                                       table, chain, rule) < 0)
+                       goto out_unfinished;
+
+               nl_dump_check_consistent(cb, nlmsg_hdr(skb));
+cont:
+               (*idx)++;
+       }
+       rc = 0;
+out_unfinished:
+       cb->args[0] = *idx;
+       return rc;
+}
+
 static int nf_tables_dump_rules(struct sk_buff *skb,
                                struct netlink_callback *cb)
 {
        const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
        const struct nft_rule_dump_ctx *ctx = cb->data;
-       const struct nft_table *table;
+       struct nft_table *table;
        const struct nft_chain *chain;
-       const struct nft_rule *rule;
-       unsigned int idx = 0, s_idx = cb->args[0];
+       unsigned int idx = 0;
        struct net *net = sock_net(skb->sk);
        int family = nfmsg->nfgen_family;
 
@@ -2313,37 +2350,34 @@ static int nf_tables_dump_rules(struct sk_buff *skb,
                if (ctx && ctx->table && strcmp(ctx->table, table->name) != 0)
                        continue;
 
-               list_for_each_entry_rcu(chain, &table->chains, list) {
-                       if (ctx && ctx->chain &&
-                           strcmp(ctx->chain, chain->name) != 0)
-                               continue;
+               if (ctx && ctx->chain) {
+                       struct rhlist_head *list, *tmp;
 
-                       list_for_each_entry_rcu(rule, &chain->rules, list) {
-                               if (!nft_is_active(net, rule))
-                                       goto cont;
-                               if (idx < s_idx)
-                                       goto cont;
-                               if (idx > s_idx)
-                                       memset(&cb->args[1], 0,
-                                              sizeof(cb->args) - sizeof(cb->args[0]));
-                               if (nf_tables_fill_rule_info(skb, net, NETLINK_CB(cb->skb).portid,
-                                                             cb->nlh->nlmsg_seq,
-                                                             NFT_MSG_NEWRULE,
-                                                             NLM_F_MULTI | NLM_F_APPEND,
-                                                             table->family,
-                                                             table, chain, rule) < 0)
-                                       goto done;
-
-                               nl_dump_check_consistent(cb, nlmsg_hdr(skb));
-cont:
-                               idx++;
+                       list = rhltable_lookup(&table->chains_ht, ctx->chain,
+                                              nft_chain_ht_params);
+                       if (!list)
+                               goto done;
+
+                       rhl_for_each_entry_rcu(chain, tmp, list, rhlhead) {
+                               if (!nft_is_active(net, chain))
+                                       continue;
+                               __nf_tables_dump_rules(skb, &idx,
+                                                      cb, table, chain);
+                               break;
                        }
+                       goto done;
                }
+
+               list_for_each_entry_rcu(chain, &table->chains, list) {
+                       if (__nf_tables_dump_rules(skb, &idx, cb, table, chain))
+                               goto done;
+               }
+
+               if (ctx && ctx->table)
+                       break;
        }
 done:
        rcu_read_unlock();
-
-       cb->args[0] = idx;
        return skb->len;
 }