This patch allows you to temporarily disable an entire table.
You can change the state of a dormant table via NFT_MSG_NEWTABLE
messages. Using this operation you can wake up a table, so their
chains are registered.
This provides atomicity at chain level. Thus, the rule-set of one
chain is applied at once, avoiding any possible intermediate state
in every chain. Still, the chains that belongs to a table are
registered consecutively. This also allows you to have inactive
tables in the kernel.
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/uapi/linux/netfilter/nf_tables.h | 11 ++++
net/netfilter/nf_tables_api.c | 97 +++++++++++++++++++++++++++---
2 files changed, 101 insertions(+), 7 deletions(-)
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 1563875..a9c4bce 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -97,13 +97,24 @@ enum nft_hook_attributes {
#define NFTA_HOOK_MAX (__NFTA_HOOK_MAX - 1)
/**
+ * enum nft_table_flags - nf_tables table flags
+ *
+ * @NFT_TABLE_F_DORMANT: this table is not active
+ */
+enum nft_table_flags {
+ NFT_TABLE_F_DORMANT = 0x1,
+};
+
+/**
* enum nft_table_attributes - nf_tables table netlink attributes
*
* @NFTA_TABLE_NAME: name of the table (NLA_STRING)
+ * @NFTA_TABLE_FLAGS: bitmask of enum nft_table_flags (NLA_U32)
*/
enum nft_table_attributes {
NFTA_TABLE_UNSPEC,
NFTA_TABLE_NAME,
+ NFTA_TABLE_FLAGS,
__NFTA_TABLE_MAX
};
#define NFTA_TABLE_MAX (__NFTA_TABLE_MAX - 1)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 61e017b..a4dd7ce 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -158,6 +158,7 @@ static int nf_tables_chain_type_lookup(const struct nft_af_info *afi,
static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
[NFTA_TABLE_NAME] = { .type = NLA_STRING },
+ [NFTA_TABLE_FLAGS] = { .type = NLA_U32 },
};
static int nf_tables_fill_table_info(struct sk_buff *skb, u32 portid, u32 seq,
@@ -177,7 +178,8 @@ static int nf_tables_fill_table_info(struct sk_buff *skb, u32 portid, u32 seq,
nfmsg->version = NFNETLINK_V0;
nfmsg->res_id = 0;
- if (nla_put_string(skb, NFTA_TABLE_NAME, table->name))
+ if (nla_put_string(skb, NFTA_TABLE_NAME, table->name) ||
+ nla_put_be32(skb, NFTA_TABLE_FLAGS, htonl(table->flags)))
goto nla_put_failure;
return nlmsg_end(skb, nlh);
@@ -301,6 +303,74 @@ err:
return err;
}
+static int nf_tables_table_enable(struct nft_table *table)
+{
+ struct nft_chain *chain;
+ int err, i = 0;
+
+ list_for_each_entry(chain, &table->chains, list) {
+ err = nf_register_hook(&nft_base_chain(chain)->ops);
+ if (err < 0)
+ goto err;
+
+ i++;
+ }
+ return 0;
+err:
+ list_for_each_entry(chain, &table->chains, list) {
+ if (i-- <= 0)
+ break;
+
+ nf_unregister_hook(&nft_base_chain(chain)->ops);
+ }
+ return err;
+}
+
+static int nf_tables_table_disable(struct nft_table *table)
+{
+ struct nft_chain *chain;
+
+ list_for_each_entry(chain, &table->chains, list)
+ nf_unregister_hook(&nft_base_chain(chain)->ops);
+
+ return 0;
+}
+
+static int nf_tables_updtable(struct sock *nlsk, struct sk_buff *skb,
+ const struct nlmsghdr *nlh,
+ const struct nlattr * const nla[],
+ struct nft_af_info *afi, struct nft_table *table)
+{
+ const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
+ int family = nfmsg->nfgen_family, ret = 0;
+
+ if (nla[NFTA_TABLE_FLAGS]) {
+ __be32 flags;
+
+ flags = ntohl(nla_get_be32(nla[NFTA_TABLE_FLAGS]));
+ if (flags & ~NFT_TABLE_F_DORMANT)
+ return -EINVAL;
+
+ if ((flags & NFT_TABLE_F_DORMANT) &&
+ !(table->flags & NFT_TABLE_F_DORMANT)) {
+ ret = nf_tables_table_disable(table);
+ if (ret >= 0)
+ table->flags |= NFT_TABLE_F_DORMANT;
+ } else if (!(flags & NFT_TABLE_F_DORMANT) &&
+ table->flags & NFT_TABLE_F_DORMANT) {
+ ret = nf_tables_table_enable(table);
+ if (ret >= 0)
+ table->flags &= ~NFT_TABLE_F_DORMANT;
+ }
+ if (ret < 0)
+ goto err;
+ }
+
+ nf_tables_table_notify(skb, nlh, table, NFT_MSG_NEWTABLE, family);
+err:
+ return ret;
+}
+
static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
const struct nlmsghdr *nlh,
const struct nlattr * const nla[])
@@ -328,7 +398,7 @@ static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
return -EEXIST;
if (nlh->nlmsg_flags & NLM_F_REPLACE)
return -EOPNOTSUPP;
- return 0;
+ return nf_tables_updtable(nlsk, skb, nlh, nla, afi, table);
}
table = kzalloc(sizeof(*table) + nla_len(name), GFP_KERNEL);
@@ -339,6 +409,18 @@ static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
INIT_LIST_HEAD(&table->chains);
INIT_LIST_HEAD(&table->sets);
+ if (nla[NFTA_TABLE_FLAGS]) {
+ __be32 flags;
+
+ flags = ntohl(nla_get_be32(nla[NFTA_TABLE_FLAGS]));
+ if (flags & ~NFT_TABLE_F_DORMANT) {
+ kfree(table);
+ return -EINVAL;
+ }
+
+ table->flags |= flags;
+ }
+
list_add_tail(&table->list, &afi->tables);
nf_tables_table_notify(skb, nlh, table, NFT_MSG_NEWTABLE, family);
return 0;
@@ -890,10 +972,8 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
chain->handle = nf_tables_alloc_handle(table);
nla_strlcpy(chain->name, name, NFT_CHAIN_MAXNAMELEN);
- list_add_tail(&chain->list, &table->chains);
- table->use++;
-
- if (chain->flags & NFT_BASE_CHAIN) {
+ if (!(table->flags & NFT_TABLE_F_DORMANT) &&
+ chain->flags & NFT_BASE_CHAIN) {
err = nf_register_hook(&nft_base_chain(chain)->ops);
if (err < 0) {
free_percpu(basechain->stats);
@@ -901,6 +981,8 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
return err;
}
}
+ list_add_tail(&chain->list, &table->chains);
+ table->use++;
notify:
nf_tables_chain_notify(skb, nlh, table, chain, NFT_MSG_NEWCHAIN,
family);
@@ -948,7 +1030,8 @@ static int nf_tables_delchain(struct sock *nlsk, struct sk_buff *skb,
list_del(&chain->list);
table->use--;
- if (chain->flags & NFT_BASE_CHAIN)
+ if (!(table->flags & NFT_TABLE_F_DORMANT) &&
+ chain->flags & NFT_BASE_CHAIN)
nf_unregister_hook(&nft_base_chain(chain)->ops);
nf_tables_chain_notify(skb, nlh, table, chain, NFT_MSG_DELCHAIN,
--
1.7.10.4
--
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