From bafbe37079500e9b591093836322da0486a9ef68 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 3 May 2019 16:18:29 +0800 Subject: [PATCH] netfilter: nf_tables: warn when expr implements only one of activate/deactivate ->destroy is only allowed to free data, or do other cleanups that do not have side effects on other state, such as visibility to other netlink requests. Such things need to be done in ->deactivate. As a transaction can fail, we need to make sure we can undo such operations, therefore ->activate() has to be provided too. So print a warning and refuse registration if expr->ops provides only one of the two operations. v2: fix nft_expr_check_ops to not repeat same check twice (Jones Desougi) Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Yang Yingliang --- net/netfilter/nf_tables_api.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index c24ea30654b9..447ad90481a1 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -207,6 +207,18 @@ static int nft_delchain(struct nft_ctx *ctx) return err; } +/* either expr ops provide both activate/deactivate, or neither */ +static bool nft_expr_check_ops(const struct nft_expr_ops *ops) +{ + if (!ops) + return true; + + if (WARN_ON_ONCE((!ops->activate ^ !ops->deactivate))) + return false; + + return true; +} + static void nft_rule_expr_activate(const struct nft_ctx *ctx, struct nft_rule *rule) { @@ -1914,6 +1926,9 @@ static int nf_tables_delchain(struct net *net, struct sock *nlsk, */ int nft_register_expr(struct nft_expr_type *type) { + if (!nft_expr_check_ops(type->ops)) + return -EINVAL; + nfnl_lock(NFNL_SUBSYS_NFTABLES); if (type->family == NFPROTO_UNSPEC) list_add_tail_rcu(&type->list, &nf_tables_expressions); @@ -2061,6 +2076,10 @@ static int nf_tables_expr_parse(const struct nft_ctx *ctx, err = PTR_ERR(ops); goto err1; } + if (!nft_expr_check_ops(ops)) { + err = -EINVAL; + goto err1; + } } else ops = type->ops; -- GitLab