From 7c1829b6aa74fff71abc1c9565151e50ad1aa3e1 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 22 Jul 2021 10:48:32 +0200 Subject: [PATCH] netfilter: ipt_CLUSTERIP: only add arp mangle hook when required Do not register the arp mangling hooks from pernet init path. As-is, load of the module is enough for these hooks to become active in each net namespace. Use checkentry instead so hook is only added if a CLUSTERIP rule is used. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 51 +++++++++++++++++++++++++------------- 1 file changed, 34 insertions(+), 17 deletions(-) diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 8f7ca67..6d7ff14 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -71,6 +71,16 @@ struct clusterip_net { /* mutex protects the config->pde*/ struct mutex mutex; #endif + unsigned int hook_users; +}; + +static unsigned int clusterip_arp_mangle(void *priv, struct sk_buff *skb, const struct nf_hook_state *state); + +static const struct nf_hook_ops cip_arp_ops = { + .hook = clusterip_arp_mangle, + .pf = NFPROTO_ARP, + .hooknum = NF_ARP_OUT, + .priority = -1 }; static unsigned int clusterip_net_id __read_mostly; @@ -458,6 +468,7 @@ clusterip_tg(struct sk_buff *skb, const struct xt_action_param *par) static int clusterip_tg_check(const struct xt_tgchk_param *par) { struct ipt_clusterip_tgt_info *cipinfo = par->targinfo; + struct clusterip_net *cn = clusterip_pernet(par->net); const struct ipt_entry *e = par->entryinfo; struct clusterip_config *config; int ret, i; @@ -467,6 +478,9 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par) return -EOPNOTSUPP; } + if (cn->hook_users == UINT_MAX) + return -EOVERFLOW; + if (cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP && cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT && cipinfo->hash_mode != CLUSTERIP_HASHMODE_SIP_SPT_DPT) { @@ -517,6 +531,19 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par) return ret; } + if (cn->hook_users == 0) { + ret = nf_register_net_hook(par->net, &cip_arp_ops); + + if (ret < 0) { + clusterip_config_entry_put(config); + clusterip_config_put(config); + nf_ct_netns_put(par->net, par->family); + return ret; + } + } + + cn->hook_users++; + if (!par->net->xt.clusterip_deprecated_warning) { pr_info("ipt_CLUSTERIP is deprecated and it will removed soon, " "use xt_cluster instead\n"); @@ -531,6 +558,7 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par) static void clusterip_tg_destroy(const struct xt_tgdtor_param *par) { const struct ipt_clusterip_tgt_info *cipinfo = par->targinfo; + struct clusterip_net *cn = clusterip_pernet(par->net); /* if no more entries are referencing the config, remove it * from the list and destroy the proc entry */ @@ -539,6 +567,10 @@ static void clusterip_tg_destroy(const struct xt_tgdtor_param *par) clusterip_config_put(cipinfo->config); nf_ct_netns_put(par->net, par->family); + cn->hook_users--; + + if (cn->hook_users == 0) + nf_unregister_net_hook(par->net, &cip_arp_ops); } #ifdef CONFIG_NETFILTER_XTABLES_COMPAT @@ -602,9 +634,8 @@ static void arp_print(struct arp_payload *payload) #endif static unsigned int -arp_mangle(void *priv, - struct sk_buff *skb, - const struct nf_hook_state *state) +clusterip_arp_mangle(void *priv, struct sk_buff *skb, + const struct nf_hook_state *state) { struct arphdr *arp = arp_hdr(skb); struct arp_payload *payload; @@ -654,13 +685,6 @@ arp_mangle(void *priv, return NF_ACCEPT; } -static const struct nf_hook_ops cip_arp_ops = { - .hook = arp_mangle, - .pf = NFPROTO_ARP, - .hooknum = NF_ARP_OUT, - .priority = -1 -}; - /*********************************************************************** * PROC DIR HANDLING ***********************************************************************/ @@ -817,20 +841,14 @@ static const struct proc_ops clusterip_proc_ops = { static int clusterip_net_init(struct net *net) { struct clusterip_net *cn = clusterip_pernet(net); - int ret; INIT_LIST_HEAD(&cn->configs); spin_lock_init(&cn->lock); - ret = nf_register_net_hook(net, &cip_arp_ops); - if (ret < 0) - return ret; - #ifdef CONFIG_PROC_FS cn->procdir = proc_mkdir("ipt_CLUSTERIP", net->proc_net); if (!cn->procdir) { - nf_unregister_net_hook(net, &cip_arp_ops); pr_err("Unable to proc dir entry\n"); return -ENOMEM; } @@ -850,7 +868,6 @@ static void clusterip_net_exit(struct net *net) cn->procdir = NULL; mutex_unlock(&cn->mutex); #endif - nf_unregister_net_hook(net, &cip_arp_ops); } static struct pernet_operations clusterip_net_ops = { -- 2.7.4