From 3dd0673ac3cd7d05cde103396ec7ec410a901de2 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sun, 5 Apr 2015 14:41:06 +0200 Subject: [PATCH] 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 --- include/net/netfilter/nf_tables.h | 4 +++- net/netfilter/nf_tables_api.c | 21 ++++++++++++--------- net/netfilter/nft_hash.c | 3 ++- 3 files changed, 17 insertions(+), 11 deletions(-) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index a785699329c9..746423332fcb 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -258,6 +258,7 @@ void nft_unregister_set(struct nft_set_ops *ops); * @dtype: data type (verdict or numeric type defined by userspace) * @size: maximum set size * @nelems: number of elements + * @ndeact: number of deactivated elements queued for removal * @timeout: default timeout value in msecs * @gc_int: garbage collection interval in msecs * @policy: set parameterization (see enum nft_set_policies) @@ -275,7 +276,8 @@ struct nft_set { u32 ktype; u32 dtype; u32 size; - u32 nelems; + atomic_t nelems; + u32 ndeact; u64 timeout; u32 gc_int; u16 policy; 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; diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c index 5923ec547268..c74e2bf1a1e4 100644 --- a/net/netfilter/nft_hash.c +++ b/net/netfilter/nft_hash.c @@ -203,7 +203,7 @@ out: static void nft_hash_gc(struct work_struct *work) { - const struct nft_set *set; + struct nft_set *set; struct nft_hash_elem *he; struct nft_hash *priv; struct nft_set_gc_batch *gcb = NULL; @@ -237,6 +237,7 @@ static void nft_hash_gc(struct work_struct *work) if (gcb == NULL) goto out; rhashtable_remove_fast(&priv->ht, &he->node, nft_hash_params); + atomic_dec(&set->nelems); nft_set_gc_batch_add(gcb, he); } out: -- 2.20.1