netfilter: nf_tables: add insert operation

This patch adds a new rule attribute NFTA_RULE_POSITION which is
used to store the position of a rule relatively to the others.
By providing the create command and specifying the position, the
rule is inserted after the rule with the handle equal to the
provided position.

Regarding notification, the position attribute specifies the
handle of the previous rule to make sure we don't point to any
stale rule in notifications coming from the commit path.

This patch includes the following fix from Pablo:

* nf_tables: fix rule deletion event reporting

Signed-off-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 7d4a1992f89c9bbbbf295e6b60fd632fcecac2a9..fbfd229a8e99e123108c6fc80dd962df683e5622 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -153,6 +153,7 @@ enum nft_chain_attributes {
  * @NFTA_RULE_HANDLE: numeric handle of the rule (NLA_U64)
  * @NFTA_RULE_EXPRESSIONS: list of expressions (NLA_NESTED: nft_expr_attributes)
  * @NFTA_RULE_COMPAT: compatibility specifications of the rule (NLA_NESTED: nft_rule_compat_attributes)
+ * @NFTA_RULE_POSITION: numeric handle of the previous rule (NLA_U64)
  */
 enum nft_rule_attributes {
        NFTA_RULE_UNSPEC,
@@ -161,6 +162,7 @@ enum nft_rule_attributes {
        NFTA_RULE_HANDLE,
        NFTA_RULE_EXPRESSIONS,
        NFTA_RULE_COMPAT,
+       NFTA_RULE_POSITION,
        __NFTA_RULE_MAX
 };
 #define NFTA_RULE_MAX          (__NFTA_RULE_MAX - 1)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index e1ee85047ec1d1d570204aa4adb47fa821157cc6..0f140663ec71b2133108d07af3506a2c5e89edbd 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1273,6 +1273,7 @@ static const struct nla_policy nft_rule_policy[NFTA_RULE_MAX + 1] = {
        [NFTA_RULE_HANDLE]      = { .type = NLA_U64 },
        [NFTA_RULE_EXPRESSIONS] = { .type = NLA_NESTED },
        [NFTA_RULE_COMPAT]      = { .type = NLA_NESTED },
+       [NFTA_RULE_POSITION]    = { .type = NLA_U64 },
 };
 
 static int nf_tables_fill_rule_info(struct sk_buff *skb, u32 portid, u32 seq,
@@ -1285,9 +1286,10 @@ static int nf_tables_fill_rule_info(struct sk_buff *skb, u32 portid, u32 seq,
        struct nfgenmsg *nfmsg;
        const struct nft_expr *expr, *next;
        struct nlattr *list;
+       const struct nft_rule *prule;
+       int type = event | NFNL_SUBSYS_NFTABLES << 8;
 
-       event |= NFNL_SUBSYS_NFTABLES << 8;
-       nlh = nlmsg_put(skb, portid, seq, event, sizeof(struct nfgenmsg),
+       nlh = nlmsg_put(skb, portid, seq, type, sizeof(struct nfgenmsg),
                        flags);
        if (nlh == NULL)
                goto nla_put_failure;
@@ -1304,6 +1306,13 @@ static int nf_tables_fill_rule_info(struct sk_buff *skb, u32 portid, u32 seq,
        if (nla_put_be64(skb, NFTA_RULE_HANDLE, cpu_to_be64(rule->handle)))
                goto nla_put_failure;
 
+       if ((event != NFT_MSG_DELRULE) && (rule->list.prev != &chain->rules)) {
+               prule = list_entry(rule->list.prev, struct nft_rule, list);
+               if (nla_put_be64(skb, NFTA_RULE_POSITION,
+                                cpu_to_be64(prule->handle)))
+                       goto nla_put_failure;
+       }
+
        list = nla_nest_start(skb, NFTA_RULE_EXPRESSIONS);
        if (list == NULL)
                goto nla_put_failure;
@@ -1499,7 +1508,7 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb,
        unsigned int size, i, n;
        int err, rem;
        bool create;
-       u64 handle;
+       u64 handle, pos_handle;
 
        create = nlh->nlmsg_flags & NLM_F_CREATE ? true : false;
 
@@ -1533,6 +1542,16 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb,
                handle = nf_tables_alloc_handle(table);
        }
 
+       if (nla[NFTA_RULE_POSITION]) {
+               if (!(nlh->nlmsg_flags & NLM_F_CREATE))
+                       return -EOPNOTSUPP;
+
+               pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
+               old_rule = __nf_tables_rule_lookup(chain, pos_handle);
+               if (IS_ERR(old_rule))
+                       return PTR_ERR(old_rule);
+       }
+
        nft_ctx_init(&ctx, skb, nlh, afi, table, chain, nla);
 
        n = 0;
@@ -1573,9 +1592,16 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb,
                list_replace_rcu(&old_rule->list, &rule->list);
                nf_tables_rule_destroy(old_rule);
        } else if (nlh->nlmsg_flags & NLM_F_APPEND)
-               list_add_tail_rcu(&rule->list, &chain->rules);
-       else
-               list_add_rcu(&rule->list, &chain->rules);
+               if (old_rule)
+                       list_add_rcu(&rule->list, &old_rule->list);
+               else
+                       list_add_tail_rcu(&rule->list, &chain->rules);
+       else {
+               if (old_rule)
+                       list_add_tail_rcu(&rule->list, &old_rule->list);
+               else
+                       list_add_rcu(&rule->list, &chain->rules);
+       }
 
        nf_tables_rule_notify(skb, nlh, table, chain, rule, NFT_MSG_NEWRULE,
                              nlh->nlmsg_flags & (NLM_F_APPEND | NLM_F_REPLACE),