From 3dd0673ac3cd7d05cde103396ec7ec410a901de2 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sun, 5 Apr 2015 14:41:06 +0200 Subject: netfilter: nf_tables: prepare set element accounting for async updates Use atomic operations for the element count to avoid races with async updates. To properly handle the transactional semantics during netlink updates, deleted but not yet committed elements are accounted for seperately and are treated as being already removed. This means for the duration of a netlink transaction, the limit might be exceeded by the amount of elements deleted. Set implementations must be prepared to handle this. Signed-off-by: Patrick McHardy Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 0dab872e821b..27d1bf55a581 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -3238,9 +3238,6 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set, u32 flags; int err; - if (set->size && set->nelems == set->size) - return -ENFILE; - err = nla_parse_nested(nla, NFTA_SET_ELEM_MAX, attr, nft_set_elem_policy); if (err < 0) @@ -3391,11 +3388,15 @@ static int nf_tables_newsetelem(struct sock *nlsk, struct sk_buff *skb, return -EBUSY; nla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) { + if (set->size && + !atomic_add_unless(&set->nelems, 1, set->size + set->ndeact)) + return -ENFILE; + err = nft_add_set_elem(&ctx, set, attr); - if (err < 0) + if (err < 0) { + atomic_dec(&set->nelems); break; - - set->nelems++; + } } return err; } @@ -3477,7 +3478,7 @@ static int nf_tables_delsetelem(struct sock *nlsk, struct sk_buff *skb, if (err < 0) break; - set->nelems--; + set->ndeact++; } return err; } @@ -3810,6 +3811,8 @@ static int nf_tables_commit(struct sk_buff *skb) &te->elem, NFT_MSG_DELSETELEM, 0); te->set->ops->remove(te->set, &te->elem); + atomic_dec(&te->set->nelems); + te->set->ndeact--; break; } } @@ -3913,16 +3916,16 @@ static int nf_tables_abort(struct sk_buff *skb) nft_trans_destroy(trans); break; case NFT_MSG_NEWSETELEM: - nft_trans_elem_set(trans)->nelems--; te = (struct nft_trans_elem *)trans->data; te->set->ops->remove(te->set, &te->elem); + atomic_dec(&te->set->nelems); break; case NFT_MSG_DELSETELEM: te = (struct nft_trans_elem *)trans->data; - nft_trans_elem_set(trans)->nelems++; te->set->ops->activate(te->set, &te->elem); + te->set->ndeact--; nft_trans_destroy(trans); break; -- cgit v1.2.3-55-g7522