From 57de2a0cd9d7e4cfc6479ecbebfcd36dbc61d5ed Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Thu, 9 Jan 2014 18:42:31 +0000 Subject: [PATCH] netfilter: nf_tables: split chain policy validation from actually setting it Currently nf_tables_newchain() atomicity is broken because of having validation of some netlink attributes performed after changing attributes of the chain. The chain policy is (currently) fine, but split it up as preparation for the following fixes and to avoid future mistakes. Signed-off-by: Patrick McHardy Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 56 ++++++++++++++++--------------------------- 1 file changed, 20 insertions(+), 36 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 572d88d..30fad4f 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -760,22 +760,6 @@ err: return err; } -static int -nf_tables_chain_policy(struct nft_base_chain *chain, const struct nlattr *attr) -{ - switch (ntohl(nla_get_be32(attr))) { - case NF_DROP: - chain->policy = NF_DROP; - break; - case NF_ACCEPT: - chain->policy = NF_ACCEPT; - break; - default: - return -EINVAL; - } - return 0; -} - static const struct nla_policy nft_counter_policy[NFTA_COUNTER_MAX + 1] = { [NFTA_COUNTER_PACKETS] = { .type = NLA_U64 }, [NFTA_COUNTER_BYTES] = { .type = NLA_U64 }, @@ -834,6 +818,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb, struct nlattr *ha[NFTA_HOOK_MAX + 1]; struct net *net = sock_net(skb->sk); int family = nfmsg->nfgen_family; + u8 policy = NF_ACCEPT; u64 handle = 0; unsigned int i; int err; @@ -869,6 +854,22 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb, } } + if (nla[NFTA_CHAIN_POLICY]) { + if ((chain != NULL && + !(chain->flags & NFT_BASE_CHAIN)) || + nla[NFTA_CHAIN_HOOK] == NULL) + return -EOPNOTSUPP; + + policy = nla_get_be32(nla[NFTA_CHAIN_POLICY]); + switch (policy) { + case NF_DROP: + case NF_ACCEPT: + break; + default: + return -EINVAL; + } + } + if (chain != NULL) { if (nlh->nlmsg_flags & NLM_F_EXCL) return -EEXIST; @@ -879,15 +880,8 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb, !IS_ERR(nf_tables_chain_lookup(table, nla[NFTA_CHAIN_NAME]))) return -EEXIST; - if (nla[NFTA_CHAIN_POLICY]) { - if (!(chain->flags & NFT_BASE_CHAIN)) - return -EOPNOTSUPP; - - err = nf_tables_chain_policy(nft_base_chain(chain), - nla[NFTA_CHAIN_POLICY]); - if (err < 0) - return err; - } + if (nla[NFTA_CHAIN_POLICY]) + nft_base_chain(chain)->policy = policy; if (nla[NFTA_CHAIN_COUNTERS]) { if (!(chain->flags & NFT_BASE_CHAIN)) @@ -958,17 +952,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb, } chain->flags |= NFT_BASE_CHAIN; - - if (nla[NFTA_CHAIN_POLICY]) { - err = nf_tables_chain_policy(basechain, - nla[NFTA_CHAIN_POLICY]); - if (err < 0) { - free_percpu(basechain->stats); - kfree(basechain); - return err; - } - } else - basechain->policy = NF_ACCEPT; + basechain->policy = policy; if (nla[NFTA_CHAIN_COUNTERS]) { err = nf_tables_counters(basechain, -- 2.7.4