From dd13b010368f85dfa59364ba87bfe8ae930b2832 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Mon, 14 Apr 2008 11:15:52 +0200 Subject: [NETFILTER]: nf_nat: kill helper and seq_adjust hooks Connection tracking helpers (specifically FTP) need to be called before NAT sequence numbers adjustments are performed to be able to compare them against previously seen ones. We've introduced two new hooks around 2.6.11 to maintain this ordering when NAT modules were changed to get called from conntrack helpers directly. The cost of netfilter hooks is quite high and sequence number adjustments are only rarely needed however. Add a RCU-protected sequence number adjustment function pointer and call it from IPv4 conntrack after calling the helper. Signed-off-by: Patrick McHardy --- net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 56 +++++++++++++------------- net/ipv4/netfilter/nf_nat_core.c | 5 +++ net/ipv4/netfilter/nf_nat_helper.c | 1 - net/ipv4/netfilter/nf_nat_standalone.c | 35 ---------------- 4 files changed, 32 insertions(+), 65 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index a65b845..41e7961 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -23,6 +23,12 @@ #include #include #include +#include + +int (*nf_nat_seq_adjust_hook)(struct sk_buff *skb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo); +EXPORT_SYMBOL_GPL(nf_nat_seq_adjust_hook); static int ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff, struct nf_conntrack_tuple *tuple) @@ -101,35 +107,41 @@ static unsigned int ipv4_confirm(unsigned int hooknum, const struct net_device *out, int (*okfn)(struct sk_buff *)) { - /* We've seen it coming out the other side: confirm it */ - return nf_conntrack_confirm(skb); -} - -static unsigned int ipv4_conntrack_help(unsigned int hooknum, - struct sk_buff *skb, - const struct net_device *in, - const struct net_device *out, - int (*okfn)(struct sk_buff *)) -{ struct nf_conn *ct; enum ip_conntrack_info ctinfo; const struct nf_conn_help *help; const struct nf_conntrack_helper *helper; + unsigned int ret; /* This is where we call the helper: as the packet goes out. */ ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY) - return NF_ACCEPT; + goto out; help = nfct_help(ct); if (!help) - return NF_ACCEPT; + goto out; + /* rcu_read_lock()ed by nf_hook_slow */ helper = rcu_dereference(help->helper); if (!helper) - return NF_ACCEPT; - return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb), - ct, ctinfo); + goto out; + + ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb), + ct, ctinfo); + if (ret != NF_ACCEPT) + return ret; + + if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) { + typeof(nf_nat_seq_adjust_hook) seq_adjust; + + seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook); + if (!seq_adjust || !seq_adjust(skb, ct, ctinfo)) + return NF_DROP; + } +out: + /* We've seen it coming out the other side: confirm it */ + return nf_conntrack_confirm(skb); } static unsigned int ipv4_conntrack_defrag(unsigned int hooknum, @@ -211,20 +223,6 @@ static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = { .priority = NF_IP_PRI_CONNTRACK, }, { - .hook = ipv4_conntrack_help, - .owner = THIS_MODULE, - .pf = PF_INET, - .hooknum = NF_INET_POST_ROUTING, - .priority = NF_IP_PRI_CONNTRACK_HELPER, - }, - { - .hook = ipv4_conntrack_help, - .owner = THIS_MODULE, - .pf = PF_INET, - .hooknum = NF_INET_LOCAL_IN, - .priority = NF_IP_PRI_CONNTRACK_HELPER, - }, - { .hook = ipv4_confirm, .owner = THIS_MODULE, .pf = PF_INET, diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c index 9320c7a..25c3efe 100644 --- a/net/ipv4/netfilter/nf_nat_core.c +++ b/net/ipv4/netfilter/nf_nat_core.c @@ -618,6 +618,9 @@ static int __init nf_nat_init(void) nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK; l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET); + + BUG_ON(nf_nat_seq_adjust_hook != NULL); + rcu_assign_pointer(nf_nat_seq_adjust_hook, nf_nat_seq_adjust); return 0; cleanup_extend: @@ -644,6 +647,8 @@ static void __exit nf_nat_cleanup(void) nf_ct_free_hashtable(bysource, nf_nat_vmalloced, nf_nat_htable_size); nf_ct_l3proto_put(l3proto); nf_ct_extend_unregister(&nat_extend); + rcu_assign_pointer(nf_nat_seq_adjust_hook, NULL); + synchronize_net(); } MODULE_LICENSE("GPL"); diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c index 2fca727..11976ea 100644 --- a/net/ipv4/netfilter/nf_nat_helper.c +++ b/net/ipv4/netfilter/nf_nat_helper.c @@ -416,7 +416,6 @@ nf_nat_seq_adjust(struct sk_buff *skb, return 1; } -EXPORT_SYMBOL(nf_nat_seq_adjust); /* Setup NAT on this expected conntrack so it follows master. */ /* If we fail to get a free NAT slot, we'll get dropped on confirm */ diff --git a/net/ipv4/netfilter/nf_nat_standalone.c b/net/ipv4/netfilter/nf_nat_standalone.c index a366b58..b7dd695 100644 --- a/net/ipv4/netfilter/nf_nat_standalone.c +++ b/net/ipv4/netfilter/nf_nat_standalone.c @@ -245,25 +245,6 @@ nf_nat_local_fn(unsigned int hooknum, return ret; } -static unsigned int -nf_nat_adjust(unsigned int hooknum, - struct sk_buff *skb, - const struct net_device *in, - const struct net_device *out, - int (*okfn)(struct sk_buff *)) -{ - struct nf_conn *ct; - enum ip_conntrack_info ctinfo; - - ct = nf_ct_get(skb, &ctinfo); - if (ct && test_bit(IPS_SEQ_ADJUST_BIT, &ct->status)) { - pr_debug("nf_nat_standalone: adjusting sequence number\n"); - if (!nf_nat_seq_adjust(skb, ct, ctinfo)) - return NF_DROP; - } - return NF_ACCEPT; -} - /* We must be after connection tracking and before packet filtering. */ static struct nf_hook_ops nf_nat_ops[] __read_mostly = { @@ -283,14 +264,6 @@ static struct nf_hook_ops nf_nat_ops[] __read_mostly = { .hooknum = NF_INET_POST_ROUTING, .priority = NF_IP_PRI_NAT_SRC, }, - /* After conntrack, adjust sequence number */ - { - .hook = nf_nat_adjust, - .owner = THIS_MODULE, - .pf = PF_INET, - .hooknum = NF_INET_POST_ROUTING, - .priority = NF_IP_PRI_NAT_SEQ_ADJUST, - }, /* Before packet filtering, change destination */ { .hook = nf_nat_local_fn, @@ -307,14 +280,6 @@ static struct nf_hook_ops nf_nat_ops[] __read_mostly = { .hooknum = NF_INET_LOCAL_IN, .priority = NF_IP_PRI_NAT_SRC, }, - /* After conntrack, adjust sequence number */ - { - .hook = nf_nat_adjust, - .owner = THIS_MODULE, - .pf = PF_INET, - .hooknum = NF_INET_LOCAL_IN, - .priority = NF_IP_PRI_NAT_SEQ_ADJUST, - }, }; static int __init nf_nat_standalone_init(void) -- cgit v1.1