diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_table_nat_ipv4.c')
-rw-r--r-- | net/ipv4/netfilter/nf_table_nat_ipv4.c | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_table_nat_ipv4.c b/net/ipv4/netfilter/nf_table_nat_ipv4.c new file mode 100644 index 0000000..2a6f184 --- /dev/null +++ b/net/ipv4/netfilter/nf_table_nat_ipv4.c @@ -0,0 +1,409 @@ +/* + * Copyright (c) 2008 Patrick McHardy <kaber@trash.net> + * + * 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. + * + * Development of this code funded by Astaro AG (http://www.astaro.com/) + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/list.h> +#include <linux/skbuff.h> +#include <linux/ip.h> +#include <linux/netlink.h> +#include <linux/netfilter.h> +#include <linux/netfilter_ipv4.h> +#include <linux/netfilter/nfnetlink.h> +#include <linux/netfilter/nf_tables.h> +#include <net/netfilter/nf_conntrack.h> +#include <net/netfilter/nf_nat.h> +#include <net/netfilter/nf_nat_core.h> +#include <net/netfilter/nf_tables.h> +#include <net/netfilter/nf_nat_l3proto.h> +#include <net/ip.h> + +struct nft_nat { + enum nft_registers sreg_addr_min:8; + enum nft_registers sreg_addr_max:8; + enum nft_registers sreg_proto_min:8; + enum nft_registers sreg_proto_max:8; + enum nf_nat_manip_type type; +}; + +static void nft_nat_eval(const struct nft_expr *expr, + struct nft_data data[NFT_REG_MAX + 1], + const struct nft_pktinfo *pkt) +{ + const struct nft_nat *priv = nft_expr_priv(expr); + enum ip_conntrack_info ctinfo; + struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo); + struct nf_nat_range range; + + memset(&range, 0, sizeof(range)); + if (priv->sreg_addr_min) { + range.min_addr.ip = data[priv->sreg_addr_min].data[0]; + range.max_addr.ip = data[priv->sreg_addr_max].data[0]; + range.flags |= NF_NAT_RANGE_MAP_IPS; + } + + if (priv->sreg_proto_min) { + range.min_proto.all = data[priv->sreg_proto_min].data[0]; + range.max_proto.all = data[priv->sreg_proto_max].data[0]; + range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED; + } + + data[NFT_REG_VERDICT].verdict = + nf_nat_setup_info(ct, &range, priv->type); +} + +static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = { + [NFTA_NAT_ADDR_MIN] = { .type = NLA_U32 }, + [NFTA_NAT_ADDR_MAX] = { .type = NLA_U32 }, + [NFTA_NAT_PROTO_MIN] = { .type = NLA_U32 }, + [NFTA_NAT_PROTO_MAX] = { .type = NLA_U32 }, + [NFTA_NAT_TYPE] = { .type = NLA_U32 }, +}; + +static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_nat *priv = nft_expr_priv(expr); + int err; + + if (tb[NFTA_NAT_TYPE] == NULL) + return -EINVAL; + + switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) { + case NFT_NAT_SNAT: + priv->type = NF_NAT_MANIP_SRC; + break; + case NFT_NAT_DNAT: + priv->type = NF_NAT_MANIP_DST; + break; + default: + return -EINVAL; + } + + if (tb[NFTA_NAT_ADDR_MIN]) { + priv->sreg_addr_min = ntohl(nla_get_be32(tb[NFTA_NAT_ADDR_MIN])); + err = nft_validate_input_register(priv->sreg_addr_min); + if (err < 0) + return err; + } + + if (tb[NFTA_NAT_ADDR_MAX]) { + priv->sreg_addr_max = ntohl(nla_get_be32(tb[NFTA_NAT_ADDR_MAX])); + err = nft_validate_input_register(priv->sreg_addr_max); + if (err < 0) + return err; + } else + priv->sreg_addr_max = priv->sreg_addr_min; + + if (tb[NFTA_NAT_PROTO_MIN]) { + priv->sreg_proto_min = ntohl(nla_get_be32(tb[NFTA_NAT_PROTO_MIN])); + err = nft_validate_input_register(priv->sreg_proto_min); + if (err < 0) + return err; + } + + if (tb[NFTA_NAT_PROTO_MAX]) { + priv->sreg_proto_max = ntohl(nla_get_be32(tb[NFTA_NAT_PROTO_MAX])); + err = nft_validate_input_register(priv->sreg_proto_max); + if (err < 0) + return err; + } else + priv->sreg_proto_max = priv->sreg_proto_min; + + return 0; +} + +static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr) +{ + const struct nft_nat *priv = nft_expr_priv(expr); + + switch (priv->type) { + case NF_NAT_MANIP_SRC: + if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT))) + goto nla_put_failure; + break; + case NF_NAT_MANIP_DST: + if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT))) + goto nla_put_failure; + break; + } + + if (nla_put_be32(skb, NFTA_NAT_ADDR_MIN, htonl(priv->sreg_addr_min))) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NAT_ADDR_MAX, htonl(priv->sreg_addr_max))) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NAT_PROTO_MIN, htonl(priv->sreg_proto_min))) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_NAT_PROTO_MAX, htonl(priv->sreg_proto_max))) + goto nla_put_failure; + return 0; + +nla_put_failure: + return -1; +} + +static struct nft_expr_ops nft_nat_ops __read_mostly = { + .name = "nat", + .size = NFT_EXPR_SIZE(sizeof(struct nft_nat)), + .owner = THIS_MODULE, + .eval = nft_nat_eval, + .init = nft_nat_init, + .dump = nft_nat_dump, + .policy = nft_nat_policy, + .maxattr = NFTA_NAT_MAX, +}; + +/* + * NAT table + */ + +static unsigned int nf_nat_fn(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + enum ip_conntrack_info ctinfo; + struct nf_conn *ct = nf_ct_get(skb, &ctinfo); + struct nf_conn_nat *nat; + enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum); + unsigned int ret; + + if (ct == NULL || nf_ct_is_untracked(ct)) + return NF_ACCEPT; + + NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET))); + + nat = nfct_nat(ct); + if (nat == NULL) { + /* Conntrack module was loaded late, can't add extension. */ + if (nf_ct_is_confirmed(ct)) + return NF_ACCEPT; + nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); + if (nat == NULL) + 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(skb, ct, ctinfo, + ops->hooknum)) + return NF_DROP; + else + return NF_ACCEPT; + } + /* Fall through */ + case IP_CT_NEW: + if (nf_nat_initialized(ct, maniptype)) + break; + + ret = nft_do_chain(ops, skb, in, out, okfn); + if (ret != NF_ACCEPT) + return ret; + if (!nf_nat_initialized(ct, maniptype)) { + ret = nf_nat_alloc_null_binding(ct, ops->hooknum); + if (ret != NF_ACCEPT) + return ret; + } + default: + break; + } + + return nf_nat_packet(ct, ctinfo, ops->hooknum, skb); +} + +static unsigned int nf_nat_prerouting(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + __be32 daddr = ip_hdr(skb)->daddr; + unsigned int ret; + + ret = nf_nat_fn(ops, skb, in, out, okfn); + if (ret != NF_DROP && ret != NF_STOLEN && + ip_hdr(skb)->daddr != daddr) { + skb_dst_drop(skb); + } + return ret; +} + +static unsigned int nf_nat_postrouting(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + enum ip_conntrack_info ctinfo __maybe_unused; + const struct nf_conn *ct __maybe_unused; + unsigned int ret; + + ret = nf_nat_fn(ops, 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 nf_xfrm_me_harder(skb, AF_INET) == 0 ? + ret : NF_DROP; + } +#endif + return ret; +} + +static unsigned int nf_nat_output(const struct nf_hook_ops *ops, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + enum ip_conntrack_info ctinfo; + const struct nf_conn *ct; + unsigned int ret; + + ret = nf_nat_fn(ops, 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 (nf_xfrm_me_harder(skb, AF_INET)) + ret = NF_DROP; +#endif + } + return ret; +} + +static struct nft_base_chain nf_chain_nat_prerouting __read_mostly = { + .chain = { + .name = "PREROUTING", + .rules = LIST_HEAD_INIT(nf_chain_nat_prerouting.chain.rules), + .flags = NFT_BASE_CHAIN | NFT_CHAIN_BUILTIN, + }, + .ops = { + .hook = nf_nat_prerouting, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_PRE_ROUTING, + .priority = NF_IP_PRI_NAT_DST, + .priv = &nf_chain_nat_prerouting.chain, + }, +}; + +static struct nft_base_chain nf_chain_nat_postrouting __read_mostly = { + .chain = { + .name = "POSTROUTING", + .rules = LIST_HEAD_INIT(nf_chain_nat_postrouting.chain.rules), + .flags = NFT_BASE_CHAIN | NFT_CHAIN_BUILTIN, + }, + .ops = { + .hook = nf_nat_postrouting, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_POST_ROUTING, + .priority = NF_IP_PRI_NAT_SRC, + .priv = &nf_chain_nat_postrouting.chain, + }, +}; + +static struct nft_base_chain nf_chain_nat_output __read_mostly = { + .chain = { + .name = "OUTPUT", + .rules = LIST_HEAD_INIT(nf_chain_nat_output.chain.rules), + .flags = NFT_BASE_CHAIN | NFT_CHAIN_BUILTIN, + }, + .ops = { + .hook = nf_nat_output, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_LOCAL_OUT, + .priority = NF_IP_PRI_NAT_DST, + .priv = &nf_chain_nat_output.chain, + }, +}; + +static struct nft_base_chain nf_chain_nat_input __read_mostly = { + .chain = { + .name = "INPUT", + .rules = LIST_HEAD_INIT(nf_chain_nat_input.chain.rules), + .flags = NFT_BASE_CHAIN | NFT_CHAIN_BUILTIN, + }, + .ops = { + .hook = nf_nat_fn, + .owner = THIS_MODULE, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_LOCAL_IN, + .priority = NF_IP_PRI_NAT_SRC, + .priv = &nf_chain_nat_input.chain, + }, +}; + + +static struct nft_table nf_table_nat_ipv4 __read_mostly = { + .name = "nat", + .chains = LIST_HEAD_INIT(nf_table_nat_ipv4.chains), +}; + +static int __init nf_table_nat_init(void) +{ + int err; + + list_add_tail(&nf_chain_nat_prerouting.chain.list, + &nf_table_nat_ipv4.chains); + list_add_tail(&nf_chain_nat_postrouting.chain.list, + &nf_table_nat_ipv4.chains); + list_add_tail(&nf_chain_nat_output.chain.list, + &nf_table_nat_ipv4.chains); + list_add_tail(&nf_chain_nat_input.chain.list, + &nf_table_nat_ipv4.chains); + + err = nft_register_table(&nf_table_nat_ipv4, NFPROTO_IPV4); + if (err < 0) + goto err1; + + err = nft_register_expr(&nft_nat_ops); + if (err < 0) + goto err2; + + return 0; + +err2: + nft_unregister_table(&nf_table_nat_ipv4, NFPROTO_IPV4); +err1: + return err; +} + +static void __exit nf_table_nat_exit(void) +{ + nft_unregister_expr(&nft_nat_ops); + nft_unregister_table(&nf_table_nat_ipv4, AF_INET); +} + +module_init(nf_table_nat_init); +module_exit(nf_table_nat_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); +MODULE_ALIAS_NFT_TABLE(AF_INET, "nat"); +MODULE_ALIAS_NFT_EXPR("nat"); |