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[/] [or1k_soc_on_altera_embedded_dev_kit/] [tags/] [linux-2.6/] [linux-2.6.24_or32_unified_v2.3/] [net/] [ipv4/] [netfilter/] [nf_nat_standalone.c] - Rev 8
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/* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/types.h> #include <linux/icmp.h> #include <linux/ip.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv4.h> #include <linux/module.h> #include <linux/skbuff.h> #include <linux/proc_fs.h> #include <net/ip.h> #include <net/checksum.h> #include <linux/spinlock.h> #include <net/netfilter/nf_conntrack.h> #include <net/netfilter/nf_conntrack_core.h> #include <net/netfilter/nf_conntrack_extend.h> #include <net/netfilter/nf_nat.h> #include <net/netfilter/nf_nat_rule.h> #include <net/netfilter/nf_nat_protocol.h> #include <net/netfilter/nf_nat_core.h> #include <net/netfilter/nf_nat_helper.h> #include <linux/netfilter_ipv4/ip_tables.h> #ifdef CONFIG_XFRM static void nat_decode_session(struct sk_buff *skb, struct flowi *fl) { struct nf_conn *ct; struct nf_conntrack_tuple *t; enum ip_conntrack_info ctinfo; enum ip_conntrack_dir dir; unsigned long statusbit; ct = nf_ct_get(skb, &ctinfo); if (ct == NULL) return; dir = CTINFO2DIR(ctinfo); t = &ct->tuplehash[dir].tuple; if (dir == IP_CT_DIR_ORIGINAL) statusbit = IPS_DST_NAT; else statusbit = IPS_SRC_NAT; if (ct->status & statusbit) { fl->fl4_dst = t->dst.u3.ip; if (t->dst.protonum == IPPROTO_TCP || t->dst.protonum == IPPROTO_UDP) fl->fl_ip_dport = t->dst.u.tcp.port; } statusbit ^= IPS_NAT_MASK; if (ct->status & statusbit) { fl->fl4_src = t->src.u3.ip; if (t->dst.protonum == IPPROTO_TCP || t->dst.protonum == IPPROTO_UDP) fl->fl_ip_sport = t->src.u.tcp.port; } } #endif static unsigned int nf_nat_fn(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; struct nf_conn_nat *nat; /* maniptype == SRC for postrouting. */ enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum); /* We never see fragments: conntrack defrags on pre-routing and local-out, and nf_nat_out protects post-routing. */ NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET))); ct = nf_ct_get(skb, &ctinfo); /* Can't track? It's not due to stress, or conntrack would have dropped it. Hence it's the user's responsibilty to packet filter it out, or implement conntrack/NAT for that protocol. 8) --RR */ if (!ct) { /* Exception: ICMP redirect to new connection (not in hash table yet). We must not let this through, in case we're doing NAT to the same network. */ if (ip_hdr(skb)->protocol == IPPROTO_ICMP) { struct icmphdr _hdr, *hp; hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); if (hp != NULL && hp->type == ICMP_REDIRECT) return NF_DROP; } return NF_ACCEPT; } /* Don't try to NAT if this packet is not conntracked */ if (ct == &nf_conntrack_untracked) return NF_ACCEPT; nat = nfct_nat(ct); if (!nat) { nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); if (nat == NULL) { pr_debug("failed to add NAT extension\n"); return NF_ACCEPT; } } switch (ctinfo) { case IP_CT_RELATED: case IP_CT_RELATED+IP_CT_IS_REPLY: if (ip_hdr(skb)->protocol == IPPROTO_ICMP) { if (!nf_nat_icmp_reply_translation(ct, ctinfo, hooknum, skb)) return NF_DROP; else return NF_ACCEPT; } /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */ case IP_CT_NEW: /* Seen it before? This can happen for loopback, retrans, or local packets.. */ if (!nf_nat_initialized(ct, maniptype)) { unsigned int ret; if (unlikely(nf_ct_is_confirmed(ct))) /* NAT module was loaded late */ ret = alloc_null_binding_confirmed(ct, hooknum); else if (hooknum == NF_IP_LOCAL_IN) /* LOCAL_IN hook doesn't have a chain! */ ret = alloc_null_binding(ct, hooknum); else ret = nf_nat_rule_find(skb, hooknum, in, out, ct); if (ret != NF_ACCEPT) { return ret; } } else pr_debug("Already setup manip %s for ct %p\n", maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST", ct); break; default: /* ESTABLISHED */ NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY)); } return nf_nat_packet(ct, ctinfo, hooknum, skb); } static unsigned int nf_nat_in(unsigned int hooknum, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { unsigned int ret; __be32 daddr = ip_hdr(skb)->daddr; ret = nf_nat_fn(hooknum, skb, in, out, okfn); if (ret != NF_DROP && ret != NF_STOLEN && daddr != ip_hdr(skb)->daddr) { dst_release(skb->dst); skb->dst = NULL; } return ret; } static unsigned int nf_nat_out(unsigned int hooknum, struct sk_buff *skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { #ifdef CONFIG_XFRM struct nf_conn *ct; enum ip_conntrack_info ctinfo; #endif unsigned int ret; /* root is playing with raw sockets. */ if (skb->len < sizeof(struct iphdr) || ip_hdrlen(skb) < sizeof(struct iphdr)) return NF_ACCEPT; ret = nf_nat_fn(hooknum, skb, in, out, okfn); #ifdef CONFIG_XFRM if (ret != NF_DROP && ret != NF_STOLEN && (ct = nf_ct_get(skb, &ctinfo)) != NULL) { enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); if (ct->tuplehash[dir].tuple.src.u3.ip != ct->tuplehash[!dir].tuple.dst.u3.ip || ct->tuplehash[dir].tuple.src.u.all != ct->tuplehash[!dir].tuple.dst.u.all ) return ip_xfrm_me_harder(skb) == 0 ? ret : NF_DROP; } #endif return ret; } static unsigned int nf_nat_local_fn(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; unsigned int ret; /* root is playing with raw sockets. */ if (skb->len < sizeof(struct iphdr) || ip_hdrlen(skb) < sizeof(struct iphdr)) return NF_ACCEPT; ret = nf_nat_fn(hooknum, skb, in, out, okfn); if (ret != NF_DROP && ret != NF_STOLEN && (ct = nf_ct_get(skb, &ctinfo)) != NULL) { enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); if (ct->tuplehash[dir].tuple.dst.u3.ip != ct->tuplehash[!dir].tuple.src.u3.ip) { if (ip_route_me_harder(skb, RTN_UNSPEC)) ret = NF_DROP; } #ifdef CONFIG_XFRM else if (ct->tuplehash[dir].tuple.dst.u.all != ct->tuplehash[!dir].tuple.src.u.all) if (ip_xfrm_me_harder(skb)) ret = NF_DROP; #endif } 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[] = { /* Before packet filtering, change destination */ { .hook = nf_nat_in, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_PRE_ROUTING, .priority = NF_IP_PRI_NAT_DST, }, /* After packet filtering, change source */ { .hook = nf_nat_out, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_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_IP_POST_ROUTING, .priority = NF_IP_PRI_NAT_SEQ_ADJUST, }, /* Before packet filtering, change destination */ { .hook = nf_nat_local_fn, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_LOCAL_OUT, .priority = NF_IP_PRI_NAT_DST, }, /* After packet filtering, change source */ { .hook = nf_nat_fn, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_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_IP_LOCAL_IN, .priority = NF_IP_PRI_NAT_SEQ_ADJUST, }, }; static int __init nf_nat_standalone_init(void) { int ret = 0; need_ipv4_conntrack(); #ifdef CONFIG_XFRM BUG_ON(ip_nat_decode_session != NULL); ip_nat_decode_session = nat_decode_session; #endif ret = nf_nat_rule_init(); if (ret < 0) { printk("nf_nat_init: can't setup rules.\n"); goto cleanup_decode_session; } ret = nf_register_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops)); if (ret < 0) { printk("nf_nat_init: can't register hooks.\n"); goto cleanup_rule_init; } return ret; cleanup_rule_init: nf_nat_rule_cleanup(); cleanup_decode_session: #ifdef CONFIG_XFRM ip_nat_decode_session = NULL; synchronize_net(); #endif return ret; } static void __exit nf_nat_standalone_fini(void) { nf_unregister_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops)); nf_nat_rule_cleanup(); #ifdef CONFIG_XFRM ip_nat_decode_session = NULL; synchronize_net(); #endif /* Conntrack caches are unregistered in nf_conntrack_cleanup */ } module_init(nf_nat_standalone_init); module_exit(nf_nat_standalone_fini); MODULE_LICENSE("GPL"); MODULE_ALIAS("ip_nat");