From 9ddf63235749a9efa1fad2eeb74be2ee9b580f8d Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 10 Oct 2013 13:26:33 +0200 Subject: [PATCH] netfilter: nf_tables: add support for dormant tables 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 --- 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 1563875e6942..a9c4bce1988f 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -96,14 +96,25 @@ 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 61e017b349cb..a4dd7ce5ec3e 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, -- 2.30.2