net/netfilter/nf_tables_netdev.c

   1 /*
   2  * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/netdevice.h>
  12 #include <net/netfilter/nf_tables.h>
  13 #include <linux/ip.h>
  14 #include <linux/ipv6.h>
  15 #include <net/netfilter/nf_tables_ipv4.h>
  16 #include <net/netfilter/nf_tables_ipv6.h>
  17
  18 static inline void
  19 nft_netdev_set_pktinfo_ipv4(struct nft_pktinfo *pkt,
  20                             struct sk_buff *skb,
  21                             const struct nf_hook_state *state)
  22 {
  23         struct iphdr *iph, _iph;
  24         u32 len, thoff;
  25
  26         nft_set_pktinfo(pkt, skb, state);
  27
  28         iph = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*iph),
  29                                  &_iph);
  30         if (!iph)
  31                 return;
  32
  33         if (iph->ihl < 5 || iph->version != 4)
  34                 return;
  35
  36         len = ntohs(iph->tot_len);
  37         thoff = iph->ihl * 4;
  38         if (skb->len < len)
  39                 return;
  40         else if (len < thoff)
  41                 return;
  42
  43         pkt->tprot = iph->protocol;
  44         pkt->xt.thoff = thoff;
  45         pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;
  46 }
  47
  48 static inline void
  49 __nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
  50                               struct sk_buff *skb,
  51                               const struct nf_hook_state *state)
  52 {
  53 #if IS_ENABLED(CONFIG_IPV6)
  54         struct ipv6hdr *ip6h, _ip6h;
  55         unsigned int thoff = 0;
  56         unsigned short frag_off;
  57         int protohdr;
  58         u32 pkt_len;
  59
  60         ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),
  61                                   &_ip6h);
  62         if (!ip6h)
  63                 return;
  64
  65         if (ip6h->version != 6)
  66                 return;
  67
  68         pkt_len = ntohs(ip6h->payload_len);
  69         if (pkt_len + sizeof(*ip6h) > skb->len)
  70                 return;
  71
  72         protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);
  73         if (protohdr < 0)
  74                 return;
  75
  76         pkt->tprot = protohdr;
  77         pkt->xt.thoff = thoff;
  78         pkt->xt.fragoff = frag_off;
  79 #endif
  80 }
  81
  82 static inline void nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
  83                                                struct sk_buff *skb,
  84                                                const struct nf_hook_state *state)
  85 {
  86         nft_set_pktinfo(pkt, skb, state);
  87         __nft_netdev_set_pktinfo_ipv6(pkt, skb, state);
  88 }
  89
  90 static unsigned int
  91 nft_do_chain_netdev(void *priv, struct sk_buff *skb,
  92                     const struct nf_hook_state *state)
  93 {
  94         struct nft_pktinfo pkt;
  95
  96         switch (skb->protocol) {
  97         case htons(ETH_P_IP):
  98                 nft_netdev_set_pktinfo_ipv4(&pkt, skb, state);
  99                 break;
 100         case htons(ETH_P_IPV6):
 101                 nft_netdev_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_netdev __read_mostly = {
 112         .family         = NFPROTO_NETDEV,
 113         .nhooks         = NF_NETDEV_NUMHOOKS,
 114         .owner          = THIS_MODULE,
 115         .flags          = NFT_AF_NEEDS_DEV,
 116         .nops           = 1,
 117         .hooks          = {
 118                 [NF_NETDEV_INGRESS]     = nft_do_chain_netdev,
 119         },
 120 };
 121
 122 static int nf_tables_netdev_init_net(struct net *net)
 123 {
 124         net->nft.netdev = kmalloc(sizeof(struct nft_af_info), GFP_KERNEL);
 125         if (net->nft.netdev == NULL)
 126                 return -ENOMEM;
 127
 128         memcpy(net->nft.netdev, &nft_af_netdev, sizeof(nft_af_netdev));
 129
 130         if (nft_register_afinfo(net, net->nft.netdev) < 0)
 131                 goto err;
 132
 133         return 0;
 134 err:
 135         kfree(net->nft.netdev);
 136         return -ENOMEM;
 137 }
 138
 139 static void nf_tables_netdev_exit_net(struct net *net)
 140 {
 141         nft_unregister_afinfo(net, net->nft.netdev);
 142         kfree(net->nft.netdev);
 143 }
 144
 145 static struct pernet_operations nf_tables_netdev_net_ops = {
 146         .init   = nf_tables_netdev_init_net,
 147         .exit   = nf_tables_netdev_exit_net,
 148 };
 149
 150 static const struct nf_chain_type nft_filter_chain_netdev = {
 151         .name           = "filter",
 152         .type           = NFT_CHAIN_T_DEFAULT,
 153         .family         = NFPROTO_NETDEV,
 154         .owner          = THIS_MODULE,
 155         .hook_mask      = (1 << NF_NETDEV_INGRESS),
 156 };
 157
 158 static void nft_netdev_event(unsigned long event, struct net_device *dev,
 159                              struct nft_ctx *ctx)
 160 {
 161         struct nft_base_chain *basechain = nft_base_chain(ctx->chain);
 162
 163         switch (event) {
 164         case NETDEV_UNREGISTER:
 165                 if (strcmp(basechain->dev_name, dev->name) != 0)
 166                         return;
 167
 168                 __nft_release_basechain(ctx);
 169                 break;
 170         case NETDEV_CHANGENAME:
 171                 if (dev->ifindex != basechain->ops[0].dev->ifindex)
 172                         return;
 173
 174                 strncpy(basechain->dev_name, dev->name, IFNAMSIZ);
 175                 break;
 176         }
 177 }
 178
 179 static int nf_tables_netdev_event(struct notifier_block *this,
 180                                   unsigned long event, void *ptr)
 181 {
 182         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 183         struct nft_af_info *afi;
 184         struct nft_table *table;
 185         struct nft_chain *chain, *nr;
 186         struct nft_ctx ctx = {
 187                 .net    = dev_net(dev),
 188         };
 189
 190         if (event != NETDEV_UNREGISTER &&
 191             event != NETDEV_CHANGENAME)
 192                 return NOTIFY_DONE;
 193
 194         nfnl_lock(NFNL_SUBSYS_NFTABLES);
 195         list_for_each_entry(afi, &dev_net(dev)->nft.af_info, list) {
 196                 ctx.afi = afi;
 197                 if (afi->family != NFPROTO_NETDEV)
 198                         continue;
 199
 200                 list_for_each_entry(table, &afi->tables, list) {
 201                         ctx.table = table;
 202                         list_for_each_entry_safe(chain, nr, &table->chains, list) {
 203                                 if (!(chain->flags & NFT_BASE_CHAIN))
 204                                         continue;
 205
 206                                 ctx.chain = chain;
 207                                 nft_netdev_event(event, dev, &ctx);
 208                         }
 209                 }
 210         }
 211         nfnl_unlock(NFNL_SUBSYS_NFTABLES);
 212
 213         return NOTIFY_DONE;
 214 }
 215
 216 static struct notifier_block nf_tables_netdev_notifier = {
 217         .notifier_call  = nf_tables_netdev_event,
 218 };
 219
 220 static int __init nf_tables_netdev_init(void)
 221 {
 222         int ret;
 223
 224         nft_register_chain_type(&nft_filter_chain_netdev);
 225         ret = register_pernet_subsys(&nf_tables_netdev_net_ops);
 226         if (ret < 0) {
 227                 nft_unregister_chain_type(&nft_filter_chain_netdev);
 228                 return ret;
 229         }
 230         register_netdevice_notifier(&nf_tables_netdev_notifier);
 231         return 0;
 232 }
 233
 234 static void __exit nf_tables_netdev_exit(void)
 235 {
 236         unregister_netdevice_notifier(&nf_tables_netdev_notifier);
 237         unregister_pernet_subsys(&nf_tables_netdev_net_ops);
 238         nft_unregister_chain_type(&nft_filter_chain_netdev);
 239 }
 240
 241 module_init(nf_tables_netdev_init);
 242 module_exit(nf_tables_netdev_exit);
 243
 244 MODULE_LICENSE("GPL");
 245 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 246 MODULE_ALIAS_NFT_FAMILY(5); /* NFPROTO_NETDEV */