[PATCH 5/7] netfilter: nf_tables: move set handling to the transaction infrastructure

[Pablo Neira Ayuso <pablo@netfilter.org>]

This patch reworks the nf_tables API so set updates are moved into
the same batch that contains rule updates. This speeds up rule-set
updates we skip a dialog of four messages between kernel and
user-space (two on each direction).

 1) create the set and send netlink message to the kernel
 2) process the response from the kernel that contains the allocated name.
 3) add the set elements and send netlink message to the kernel.
 4) process the response from the kernel (to check for errors).

To:

 1) add the set to the batch.
 2) add the set elements to the batch.
 3) add the rule that points to the set.
 4) send batch to the kernel.

The idea is to allocate an internal set ID to the batch that can be
used when adding set elements and rules that refer to the set in the
batch.

Note that this patch doesn't add atomic set element updates, it just
helps to leave the set configuration in consistent state in case
that we fail to load the entire batch for some reason.

Backward compatibility has been only retained in userspace, this
means that new nft versions can talk to the kernel both in the new
and the old fashion.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h        |    7 ++
 include/uapi/linux/netfilter/nf_tables.h |    6 ++
 net/netfilter/nf_tables_api.c            |  130 +++++++++++++++++++++++++++---
 net/netfilter/nft_lookup.c               |   15 +++-
 4 files changed, 141 insertions(+), 17 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 03940f3..02e990d 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -222,6 +222,8 @@ static inline void *nft_set_priv(const struct nft_set *set)
 
 struct nft_set *nf_tables_set_lookup(const struct nft_table *table,
 				     const struct nlattr *nla);
+struct nft_set *nf_tables_set_lookup_byid(const struct net *net,
+					  const struct nlattr *nla);
 
 /**
  *	struct nft_set_binding - nf_tables set binding
@@ -342,6 +344,7 @@ struct nft_rule {
 
 enum nft_trans_type {
 	NFT_TRANS_RULE,
+	NFT_TRANS_SET,
 };
 
 /**
@@ -357,6 +360,10 @@ struct nft_trans {
 	struct nft_ctx			ctx;
 	union {
 		struct nft_rule		*rule;
+		struct {
+			struct nft_set	*set;
+			u32		set_id;
+		};
 	};
 };
 
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index c88ccbf..8427e17 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -221,6 +221,7 @@ enum nft_set_flags {
  * @NFTA_SET_KEY_LEN: key data length (NLA_U32)
  * @NFTA_SET_DATA_TYPE: mapping data type (NLA_U32)
  * @NFTA_SET_DATA_LEN: mapping data length (NLA_U32)
+ * @NFTA_SET_ID: uniquely identifies a set in a transaction (NLA_U32)
  */
 enum nft_set_attributes {
 	NFTA_SET_UNSPEC,
@@ -231,6 +232,7 @@ enum nft_set_attributes {
 	NFTA_SET_KEY_LEN,
 	NFTA_SET_DATA_TYPE,
 	NFTA_SET_DATA_LEN,
+	NFTA_SET_ID,
 	__NFTA_SET_MAX
 };
 #define NFTA_SET_MAX		(__NFTA_SET_MAX - 1)
@@ -266,12 +268,14 @@ enum nft_set_elem_attributes {
  * @NFTA_SET_ELEM_LIST_TABLE: table of the set to be changed (NLA_STRING)
  * @NFTA_SET_ELEM_LIST_SET: name of the set to be changed (NLA_STRING)
  * @NFTA_SET_ELEM_LIST_ELEMENTS: list of set elements (NLA_NESTED: nft_set_elem_attributes)
+ * @NFTA_SET_ELEM_LIST_SET_ID: uniquely identifies a set in a transaction (NLA_U32)
  */
 enum nft_set_elem_list_attributes {
 	NFTA_SET_ELEM_LIST_UNSPEC,
 	NFTA_SET_ELEM_LIST_TABLE,
 	NFTA_SET_ELEM_LIST_SET,
 	NFTA_SET_ELEM_LIST_ELEMENTS,
+	NFTA_SET_ELEM_LIST_SET_ID,
 	__NFTA_SET_ELEM_LIST_MAX
 };
 #define NFTA_SET_ELEM_LIST_MAX	(__NFTA_SET_ELEM_LIST_MAX - 1)
@@ -457,12 +461,14 @@ enum nft_cmp_attributes {
  * @NFTA_LOOKUP_SET: name of the set where to look for (NLA_STRING)
  * @NFTA_LOOKUP_SREG: source register of the data to look for (NLA_U32: nft_registers)
  * @NFTA_LOOKUP_DREG: destination register (NLA_U32: nft_registers)
+ * @NFTA_LOOKUP_SET_ID: uniquely identifies a set in a transaction (NLA_U32)
  */
 enum nft_lookup_attributes {
 	NFTA_LOOKUP_UNSPEC,
 	NFTA_LOOKUP_SET,
 	NFTA_LOOKUP_SREG,
 	NFTA_LOOKUP_DREG,
+	NFTA_LOOKUP_SET_ID,
 	__NFTA_LOOKUP_MAX
 };
 #define NFTA_LOOKUP_MAX		(__NFTA_LOOKUP_MAX - 1)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4d4d5fc..0b2fb07 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1884,6 +1884,7 @@ static const struct nla_policy nft_set_policy[NFTA_SET_MAX + 1] = {
 	[NFTA_SET_KEY_LEN]		= { .type = NLA_U32 },
 	[NFTA_SET_DATA_TYPE]		= { .type = NLA_U32 },
 	[NFTA_SET_DATA_LEN]		= { .type = NLA_U32 },
+	[NFTA_SET_ID]			= { .type = NLA_U32 },
 };
 
 static int nft_ctx_init_from_setattr(struct nft_ctx *ctx,
@@ -1930,6 +1931,22 @@ struct nft_set *nf_tables_set_lookup(const struct nft_table *table,
 	return ERR_PTR(-ENOENT);
 }
 
+struct nft_set *nf_tables_set_lookup_byid(const struct net *net,
+					  const struct nlattr *nla)
+{
+	struct nft_trans *trans;
+	u32 id = ntohl(nla_get_be32(nla));
+
+	list_for_each_entry(trans, &net->nft.commit_list, list) {
+		if (trans->type != NFT_TRANS_SET)
+			continue;
+
+		if (id == trans->set_id)
+			return trans->set;
+	}
+	return ERR_PTR(-ENOENT);
+}
+
 static int nf_tables_set_alloc_name(struct nft_ctx *ctx, struct nft_set *set,
 				    const char *name)
 {
@@ -2236,6 +2253,33 @@ err:
 	return err;
 }
 
+/* Internal set flags */
+#define __NFT_SET_DYING		(1 << 14)
+#define __NFT_SET_INACTIVE	(1 << 15)
+#define __NFT_SET_MASK		(__NFT_SET_DYING | __NFT_SET_INACTIVE)
+
+static int nft_set_trans_add(struct nft_ctx *ctx, struct nft_set *set)
+{
+	struct nft_trans *trans;
+
+	/* You cannot delete an existing set twice */
+	if (set->flags & __NFT_SET_DYING)
+		return -ENOENT;
+
+	trans = nft_trans_alloc(ctx, NFT_TRANS_SET);
+	if (trans == NULL)
+		return -ENOMEM;
+
+	trans->set = set;
+	if (ctx->nla[NFTA_SET_ID])
+		trans->set_id = ntohl(nla_get_be32(ctx->nla[NFTA_SET_ID]));
+
+	set->flags |= __NFT_SET_INACTIVE;
+	list_add_tail(&trans->list, &ctx->net->nft.commit_list);
+
+	return 0;
+}
+
 static int nf_tables_newset(struct sock *nlsk, struct sk_buff *skb,
 			    const struct nlmsghdr *nlh,
 			    const struct nlattr * const nla[])
@@ -2360,8 +2404,10 @@ static int nf_tables_newset(struct sock *nlsk, struct sk_buff *skb,
 	if (err < 0)
 		goto err2;
 
-	list_add_tail(&set->list, &table->sets);
-	nf_tables_set_notify(&ctx, set, NFT_MSG_NEWSET);
+	err = nft_set_trans_add(&ctx, set);
+	if (err < 0)
+		goto err2;
+
 	return 0;
 
 err2:
@@ -2371,16 +2417,20 @@ err1:
 	return err;
 }
 
-static void nf_tables_set_destroy(const struct nft_ctx *ctx, struct nft_set *set)
+static void nft_set_destroy(struct nft_set *set)
 {
-	list_del(&set->list);
-	nf_tables_set_notify(ctx, set, NFT_MSG_DELSET);
-
 	set->ops->destroy(set);
 	module_put(set->ops->owner);
 	kfree(set);
 }
 
+static void nf_tables_set_destroy(const struct nft_ctx *ctx, struct nft_set *set)
+{
+	list_del(&set->list);
+	nf_tables_set_notify(ctx, set, NFT_MSG_DELSET);
+	nft_set_destroy(set);
+}
+
 static int nf_tables_delset(struct sock *nlsk, struct sk_buff *skb,
 			    const struct nlmsghdr *nlh,
 			    const struct nlattr * const nla[])
@@ -2405,7 +2455,14 @@ static int nf_tables_delset(struct sock *nlsk, struct sk_buff *skb,
 	if (!list_empty(&set->bindings))
 		return -EBUSY;
 
-	nf_tables_set_destroy(&ctx, set);
+	set->flags |= __NFT_SET_DYING;
+
+	err = nft_set_trans_add(&ctx, set);
+	if (err < 0) {
+		set->flags &= ~__NFT_SET_DYING;
+		return err;
+	}
+
 	return 0;
 }
 
@@ -2465,7 +2522,8 @@ void nf_tables_unbind_set(const struct nft_ctx *ctx, struct nft_set *set,
 {
 	list_del(&binding->list);
 
-	if (list_empty(&set->bindings) && set->flags & NFT_SET_ANONYMOUS)
+	if (list_empty(&set->bindings) && set->flags & NFT_SET_ANONYMOUS &&
+	    !(set->flags & __NFT_SET_INACTIVE))
 		nf_tables_set_destroy(ctx, set);
 }
 
@@ -2483,6 +2541,7 @@ static const struct nla_policy nft_set_elem_list_policy[NFTA_SET_ELEM_LIST_MAX +
 	[NFTA_SET_ELEM_LIST_TABLE]	= { .type = NLA_STRING },
 	[NFTA_SET_ELEM_LIST_SET]	= { .type = NLA_STRING },
 	[NFTA_SET_ELEM_LIST_ELEMENTS]	= { .type = NLA_NESTED },
+	[NFTA_SET_ELEM_LIST_SET_ID]	= { .type = NLA_U32 },
 };
 
 static int nft_ctx_init_from_elemattr(struct nft_ctx *ctx,
@@ -2746,6 +2805,7 @@ static int nf_tables_newsetelem(struct sock *nlsk, struct sk_buff *skb,
 				const struct nlmsghdr *nlh,
 				const struct nlattr * const nla[])
 {
+	struct net *net = sock_net(skb->sk);
 	const struct nlattr *attr;
 	struct nft_set *set;
 	struct nft_ctx ctx;
@@ -2755,7 +2815,13 @@ static int nf_tables_newsetelem(struct sock *nlsk, struct sk_buff *skb,
 	if (err < 0)
 		return err;
 
-	set = nf_tables_set_lookup(ctx.table, nla[NFTA_SET_ELEM_LIST_SET]);
+	if (nla[NFTA_SET_ELEM_LIST_SET_ID]) {
+		set = nf_tables_set_lookup_byid(net,
+						nla[NFTA_SET_ELEM_LIST_SET_ID]);
+	} else {
+		set = nf_tables_set_lookup(ctx.table,
+					   nla[NFTA_SET_ELEM_LIST_SET]);
+	}
 	if (IS_ERR(set))
 		return PTR_ERR(set);
 	if (!list_empty(&set->bindings) && set->flags & NFT_SET_CONSTANT)
@@ -2884,7 +2950,7 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
 		.policy		= nft_rule_policy,
 	},
 	[NFT_MSG_NEWSET] = {
-		.call		= nf_tables_newset,
+		.call_batch	= nf_tables_newset,
 		.attr_count	= NFTA_SET_MAX,
 		.policy		= nft_set_policy,
 	},
@@ -2894,12 +2960,12 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
 		.policy		= nft_set_policy,
 	},
 	[NFT_MSG_DELSET] = {
-		.call		= nf_tables_delset,
+		.call_batch	= nf_tables_delset,
 		.attr_count	= NFTA_SET_MAX,
 		.policy		= nft_set_policy,
 	},
 	[NFT_MSG_NEWSETELEM] = {
-		.call		= nf_tables_newsetelem,
+		.call_batch	= nf_tables_newsetelem,
 		.attr_count	= NFTA_SET_ELEM_LIST_MAX,
 		.policy		= nft_set_elem_list_policy,
 	},
@@ -2909,7 +2975,7 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
 		.policy		= nft_set_elem_list_policy,
 	},
 	[NFT_MSG_DELSETELEM] = {
-		.call		= nf_tables_delsetelem,
+		.call_batch	= nf_tables_delsetelem,
 		.attr_count	= NFTA_SET_ELEM_LIST_MAX,
 		.policy		= nft_set_elem_list_policy,
 	},
@@ -2941,6 +3007,20 @@ static void nft_rule_commit_update(struct net *net, struct sk_buff *skb,
 			      trans->ctx.afi->family);
 }
 
+static void nft_set_commit_update(struct nft_trans *trans)
+{
+	if (trans->set->flags & __NFT_SET_DYING) {
+		list_del(&trans->set->list);
+		nf_tables_set_notify(&trans->ctx, trans->set, NFT_MSG_DELSET);
+	} else {
+		list_add_tail(&trans->set->list, &trans->ctx.table->sets);
+		trans->set->flags &= ~__NFT_SET_MASK;
+		nf_tables_set_notify(&trans->ctx, trans->set, NFT_MSG_NEWSET);
+		list_del(&trans->list);
+		kfree(trans);
+	}
+}
+
 static int nf_tables_commit(struct sk_buff *skb)
 {
 	struct net *net = sock_net(skb->sk);
@@ -2962,6 +3042,9 @@ static int nf_tables_commit(struct sk_buff *skb)
 		case NFT_TRANS_RULE:
 			nft_rule_commit_update(net, skb, trans);
 			break;
+		case NFT_TRANS_SET:
+			nft_set_commit_update(trans);
+			break;
 		}
 	}
 
@@ -2975,6 +3058,10 @@ static int nf_tables_commit(struct sk_buff *skb)
 		case NFT_TRANS_RULE:
 			nf_tables_rule_destroy(&trans->ctx, trans->rule);
 			break;
+		case NFT_TRANS_SET:
+			trans->set->flags &= ~__NFT_SET_MASK;
+			nft_set_destroy(trans->set);
+			break;
 		}
 		kfree(trans);
 	}
@@ -3001,6 +3088,18 @@ static void nft_rule_abort_undo(struct net *net, struct sk_buff *skb,
 	list_del_rcu(&trans->rule->list);
 }
 
+static void nft_set_abort(struct nft_trans *trans)
+{
+	/* This set was scheduled for removal, clear the dying flags to leave
+	 * it in place. Otherwise, it's a new one that we need to release as
+	 * the transaction was aborted.
+	 */
+	if (trans->set->flags & __NFT_SET_DYING)
+		trans->set->flags &= ~__NFT_SET_MASK;
+	else
+		nft_set_destroy(trans->set);
+}
+
 static int nf_tables_abort(struct sk_buff *skb)
 {
 	struct net *net = sock_net(skb->sk);
@@ -3011,6 +3110,8 @@ static int nf_tables_abort(struct sk_buff *skb)
 		case NFT_TRANS_RULE:
 			nft_rule_abort_undo(net, skb, trans);
 			break;
+		case NFT_TRANS_SET:
+			break;
 		}
 	}
 
@@ -3026,6 +3127,9 @@ static int nf_tables_abort(struct sk_buff *skb)
 			 */
 			nf_tables_rule_destroy(&trans->ctx, trans->rule);
 			break;
+		case NFT_TRANS_SET:
+			nft_set_abort(trans);
+			break;
 		}
 		kfree(trans);
 	}
diff --git a/net/netfilter/nft_lookup.c b/net/netfilter/nft_lookup.c
index 7fd2bea..201fbb5 100644
--- a/net/netfilter/nft_lookup.c
+++ b/net/netfilter/nft_lookup.c
@@ -51,13 +51,20 @@ static int nft_lookup_init(const struct nft_ctx *ctx,
 	struct nft_set *set;
 	int err;
 
-	if (tb[NFTA_LOOKUP_SET] == NULL ||
+	if ((tb[NFTA_LOOKUP_SET] == NULL && tb[NFTA_LOOKUP_SET_ID] == NULL) ||
 	    tb[NFTA_LOOKUP_SREG] == NULL)
 		return -EINVAL;
 
-	set = nf_tables_set_lookup(ctx->table, tb[NFTA_LOOKUP_SET]);
-	if (IS_ERR(set))
-		return PTR_ERR(set);
+	if (tb[NFTA_LOOKUP_SET_ID]) {
+		set = nf_tables_set_lookup_byid(ctx->net,
+						tb[NFTA_LOOKUP_SET_ID]);
+		if (IS_ERR(set))
+			return PTR_ERR(set);
+	} else {
+		set = nf_tables_set_lookup(ctx->table, tb[NFTA_LOOKUP_SET]);
+		if (IS_ERR(set))
+			return PTR_ERR(set);
+	}
 
 	priv->sreg = ntohl(nla_get_be32(tb[NFTA_LOOKUP_SREG]));
 	err = nft_validate_input_register(priv->sreg);
-- 
1.7.10.4