[PATCH 19/21] netfilter: nf_tables: add NFTA_RULE_ID attribute

[Pablo Neira Ayuso]

This new attribute allows us to uniquely identify a rule in transaction.
Robots may trigger an insertion followed by deletion in a batch, in that
scenario we still don't have a public rule handle that we can use to
delete the rule. This is similar to the NFTA_SET_ID attribute that
allows us to refer to an anonymous set from a batch.

Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 include/net/netfilter/nf_tables.h        |  3 +++
 include/uapi/linux/netfilter/nf_tables.h |  2 ++
 net/netfilter/nf_tables_api.c            | 26 ++++++++++++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/include/net/netfilter/nf_tables.h 
b/include/net/netfilter/nf_tables.h
index 21ce50e6d0c5..ac84686aaafb 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1202,10 +1202,13 @@ struct nft_trans {
 
 struct nft_trans_rule {
        struct nft_rule                 *rule;
+       u32                             rule_id;
 };
 
 #define nft_trans_rule(trans)  \
        (((struct nft_trans_rule *)trans->data)->rule)
+#define nft_trans_rule_id(trans)       \
+       (((struct nft_trans_rule *)trans->data)->rule_id)
 
 struct nft_trans_set {
        struct nft_set                  *set;
diff --git a/include/uapi/linux/netfilter/nf_tables.h 
b/include/uapi/linux/netfilter/nf_tables.h
index 207951516ede..05215d30fe5c 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -207,6 +207,7 @@ enum nft_chain_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)
  * @NFTA_RULE_USERDATA: user data (NLA_BINARY, NFT_USERDATA_MAXLEN)
+ * @NFTA_RULE_ID: uniquely identifies a rule in a transaction (NLA_U32)
  */
 enum nft_rule_attributes {
        NFTA_RULE_UNSPEC,
@@ -218,6 +219,7 @@ enum nft_rule_attributes {
        NFTA_RULE_POSITION,
        NFTA_RULE_USERDATA,
        NFTA_RULE_PAD,
+       NFTA_RULE_ID,
        __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 71c60a04b66b..6c782532615f 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -240,6 +240,10 @@ static struct nft_trans *nft_trans_rule_add(struct nft_ctx 
*ctx, int msg_type,
        if (trans == NULL)
                return NULL;
 
+       if (msg_type == NFT_MSG_NEWRULE && ctx->nla[NFTA_RULE_ID] != NULL) {
+               nft_trans_rule_id(trans) =
+                       ntohl(nla_get_be32(ctx->nla[NFTA_RULE_ID]));
+       }
        nft_trans_rule(trans) = rule;
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);
 
@@ -2293,6 +2297,22 @@ static int nf_tables_newrule(struct net *net, struct 
sock *nlsk,
        return err;
 }
 
+static struct nft_rule *nft_rule_lookup_byid(const struct net *net,
+                                            const struct nlattr *nla)
+{
+       u32 id = ntohl(nla_get_be32(nla));
+       struct nft_trans *trans;
+
+       list_for_each_entry(trans, &net->nft.commit_list, list) {
+               struct nft_rule *rule = nft_trans_rule(trans);
+
+               if (trans->msg_type == NFT_MSG_NEWRULE &&
+                   id == nft_trans_rule_id(trans))
+                       return rule;
+       }
+       return ERR_PTR(-ENOENT);
+}
+
 static int nf_tables_delrule(struct net *net, struct sock *nlsk,
                             struct sk_buff *skb, const struct nlmsghdr *nlh,
                             const struct nlattr * const nla[])
@@ -2331,6 +2351,12 @@ static int nf_tables_delrule(struct net *net, struct 
sock *nlsk,
                                return PTR_ERR(rule);
 
                        err = nft_delrule(&ctx, rule);
+               } else if (nla[NFTA_RULE_ID]) {
+                       rule = nft_rule_lookup_byid(net, nla[NFTA_RULE_ID]);
+                       if (IS_ERR(rule))
+                               return PTR_ERR(rule);
+
+                       err = nft_delrule(&ctx, rule);
                } else {
                        err = nft_delrule_by_chain(&ctx);
                }
-- 
2.1.4