net/bridge/netfilter/nf_tables_bridge.c

   1 /*
   2  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   3  * Copyright (c) 2013 Pablo Neira Ayuso <pablo@netfilter.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Development of this code funded by Astaro AG (http://www.astaro.com/)
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/netfilter_bridge.h>
  15 #include <net/netfilter/nf_tables.h>
  16 #include <net/netfilter/nf_tables_bridge.h>
  17 #include <linux/ip.h>
  18 #include <linux/ipv6.h>
  19 #include <net/netfilter/nf_tables_ipv4.h>
  20 #include <net/netfilter/nf_tables_ipv6.h>
  21
  22 int nft_bridge_iphdr_validate(struct sk_buff *skb)
  23 {
  24         struct iphdr *iph;
  25         u32 len;
  26
  27         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  28                 return 0;
  29
  30         iph = ip_hdr(skb);
  31         if (iph->ihl < 5 || iph->version != 4)
  32                 return 0;
  33
  34         len = ntohs(iph->tot_len);
  35         if (skb->len < len)
  36                 return 0;
  37         else if (len < (iph->ihl*4))
  38                 return 0;
  39
  40         if (!pskb_may_pull(skb, iph->ihl*4))
  41                 return 0;
  42
  43         return 1;
  44 }
  45 EXPORT_SYMBOL_GPL(nft_bridge_iphdr_validate);
  46
  47 int nft_bridge_ip6hdr_validate(struct sk_buff *skb)
  48 {
  49         struct ipv6hdr *hdr;
  50         u32 pkt_len;
  51
  52         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  53                 return 0;
  54
  55         hdr = ipv6_hdr(skb);
  56         if (hdr->version != 6)
  57                 return 0;
  58
  59         pkt_len = ntohs(hdr->payload_len);
  60         if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
  61                 return 0;
  62
  63         return 1;
  64 }
  65 EXPORT_SYMBOL_GPL(nft_bridge_ip6hdr_validate);
  66
  67 static inline void nft_bridge_set_pktinfo_ipv4(struct nft_pktinfo *pkt,
  68                                                struct sk_buff *skb,
  69                                                const struct nf_hook_state *state)
  70 {
  71         if (nft_bridge_iphdr_validate(skb))
  72                 nft_set_pktinfo_ipv4(pkt, skb, state);
  73         else
  74                 nft_set_pktinfo(pkt, skb, state);
  75 }
  76
  77 static inline void nft_bridge_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
  78                                                struct sk_buff *skb,
  79                                                const struct nf_hook_state *state)
  80 {
  81 #if IS_ENABLED(CONFIG_IPV6)
  82         if (nft_bridge_ip6hdr_validate(skb) &&
  83             nft_set_pktinfo_ipv6(pkt, skb, state) == 0)
  84                 return;
  85 #endif
  86         nft_set_pktinfo(pkt, skb, state);
  87 }
  88
  89 static unsigned int
  90 nft_do_chain_bridge(void *priv,
  91                     struct sk_buff *skb,
  92                     const struct nf_hook_state *state)
  93 {
  94         struct nft_pktinfo pkt;
  95
  96         switch (eth_hdr(skb)->h_proto) {
  97         case htons(ETH_P_IP):
  98                 nft_bridge_set_pktinfo_ipv4(&pkt, skb, state);
  99                 break;
 100         case htons(ETH_P_IPV6):
 101                 nft_bridge_set_pktinfo_ipv6(&pkt, skb, state);
 102                 break;
 103         default:
 104                 nft_set_pktinfo(&pkt, skb, state);
 105                 break;
 106         }
 107
 108         return nft_do_chain(&pkt, priv);
 109 }
 110
 111 static struct nft_af_info nft_af_bridge __read_mostly = {
 112         .family         = NFPROTO_BRIDGE,
 113         .nhooks         = NF_BR_NUMHOOKS,
 114         .owner          = THIS_MODULE,
 115         .nops           = 1,
 116         .hooks          = {
 117                 [NF_BR_PRE_ROUTING]     = nft_do_chain_bridge,
 118                 [NF_BR_LOCAL_IN]        = nft_do_chain_bridge,
 119                 [NF_BR_FORWARD]         = nft_do_chain_bridge,
 120                 [NF_BR_LOCAL_OUT]       = nft_do_chain_bridge,
 121                 [NF_BR_POST_ROUTING]    = nft_do_chain_bridge,
 122         },
 123 };
 124
 125 static int nf_tables_bridge_init_net(struct net *net)
 126 {
 127         net->nft.bridge = kmalloc(sizeof(struct nft_af_info), GFP_KERNEL);
 128         if (net->nft.bridge == NULL)
 129                 return -ENOMEM;
 130
 131         memcpy(net->nft.bridge, &nft_af_bridge, sizeof(nft_af_bridge));
 132
 133         if (nft_register_afinfo(net, net->nft.bridge) < 0)
 134                 goto err;
 135
 136         return 0;
 137 err:
 138         kfree(net->nft.bridge);
 139         return -ENOMEM;
 140 }
 141
 142 static void nf_tables_bridge_exit_net(struct net *net)
 143 {
 144         nft_unregister_afinfo(net->nft.bridge);
 145         kfree(net->nft.bridge);
 146 }
 147
 148 static struct pernet_operations nf_tables_bridge_net_ops = {
 149         .init   = nf_tables_bridge_init_net,
 150         .exit   = nf_tables_bridge_exit_net,
 151 };
 152
 153 static const struct nf_chain_type filter_bridge = {
 154         .name           = "filter",
 155         .type           = NFT_CHAIN_T_DEFAULT,
 156         .family         = NFPROTO_BRIDGE,
 157         .owner          = THIS_MODULE,
 158         .hook_mask      = (1 << NF_BR_PRE_ROUTING) |
 159                           (1 << NF_BR_LOCAL_IN) |
 160                           (1 << NF_BR_FORWARD) |
 161                           (1 << NF_BR_LOCAL_OUT) |
 162                           (1 << NF_BR_POST_ROUTING),
 163 };
 164
 165 static int __init nf_tables_bridge_init(void)
 166 {
 167         int ret;
 168
 169         nft_register_chain_type(&filter_bridge);
 170         ret = register_pernet_subsys(&nf_tables_bridge_net_ops);
 171         if (ret < 0)
 172                 nft_unregister_chain_type(&filter_bridge);
 173
 174         return ret;
 175 }
 176
 177 static void __exit nf_tables_bridge_exit(void)
 178 {
 179         unregister_pernet_subsys(&nf_tables_bridge_net_ops);
 180         nft_unregister_chain_type(&filter_bridge);
 181 }
 182
 183 module_init(nf_tables_bridge_init);
 184 module_exit(nf_tables_bridge_exit);
 185
 186 MODULE_LICENSE("GPL");
 187 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 188 MODULE_ALIAS_NFT_FAMILY(AF_BRIDGE);