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         iph = ip_hdr(skb);
  34         if (iph->ihl < 5 || iph->version != 4)
  35                 return;
  36
  37         len = ntohs(iph->tot_len);
  38         thoff = iph->ihl * 4;
  39         if (skb->len < len)
  40                 return;
  41         else if (len < thoff)
  42                 return;
  43
  44         pkt->tprot = iph->protocol;
  45         pkt->xt.thoff = thoff;
  46         pkt->xt.fragoff = ntohs(iph->frag_off) & IP_OFFSET;
  47 }
  48
  49 static inline void
  50 __nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
  51                               struct sk_buff *skb,
  52                               const struct nf_hook_state *state)
  53 {
  54 #if IS_ENABLED(CONFIG_IPV6)
  55         struct ipv6hdr *ip6h, _ip6h;
  56         unsigned int thoff = 0;
  57         unsigned short frag_off;
  58         int protohdr;
  59         u32 pkt_len;
  60
  61         ip6h = skb_header_pointer(skb, skb_network_offset(skb), sizeof(*ip6h),
  62                                   &_ip6h);
  63         if (!ip6h)
  64                 return;
  65
  66         if (ip6h->version != 6)
  67                 return;
  68
  69         pkt_len = ntohs(ip6h->payload_len);
  70         if (pkt_len + sizeof(*ip6h) > skb->len)
  71                 return;
  72
  73         protohdr = ipv6_find_hdr(pkt->skb, &thoff, -1, &frag_off, NULL);
  74         if (protohdr < 0)
  75                 return;
  76
  77         pkt->tprot = protohdr;
  78         pkt->xt.thoff = thoff;
  79         pkt->xt.fragoff = frag_off;
  80 #endif
  81 }
  82
  83 static inline void nft_netdev_set_pktinfo_ipv6(struct nft_pktinfo *pkt,
  84                                                struct sk_buff *skb,
  85                                                const struct nf_hook_state *state)
  86 {
  87         nft_set_pktinfo(pkt, skb, state);
  88         __nft_netdev_set_pktinfo_ipv6(pkt, skb, state);
  89 }
  90
  91 static unsigned int
  92 nft_do_chain_netdev(void *priv, struct sk_buff *skb,
  93                     const struct nf_hook_state *state)
  94 {
  95         struct nft_pktinfo pkt;
  96
  97         switch (skb->protocol) {
  98         case htons(ETH_P_IP):
  99                 nft_netdev_set_pktinfo_ipv4(&pkt, skb, state);
 100                 break;
 101         case htons(ETH_P_IPV6):
 102                 nft_netdev_set_pktinfo_ipv6(&pkt, skb, state);
 103                 break;
 104         default:
 105                 nft_set_pktinfo(&pkt, skb, state);
 106                 break;
 107         }
 108
 109         return nft_do_chain(&pkt, priv);
 110 }
 111
 112 static struct nft_af_info nft_af_netdev __read_mostly = {
 113         .family         = NFPROTO_NETDEV,
 114         .nhooks         = NF_NETDEV_NUMHOOKS,
 115         .owner          = THIS_MODULE,
 116         .flags          = NFT_AF_NEEDS_DEV,
 117         .nops           = 1,
 118         .hooks          = {
 119                 [NF_NETDEV_INGRESS]     = nft_do_chain_netdev,
 120         },
 121 };
 122
 123 static int nf_tables_netdev_init_net(struct net *net)
 124 {
 125         net->nft.netdev = kmalloc(sizeof(struct nft_af_info), GFP_KERNEL);
 126         if (net->nft.netdev == NULL)
 127                 return -ENOMEM;
 128
 129         memcpy(net->nft.netdev, &nft_af_netdev, sizeof(nft_af_netdev));
 130
 131         if (nft_register_afinfo(net, net->nft.netdev) < 0)
 132                 goto err;
 133
 134         return 0;
 135 err:
 136         kfree(net->nft.netdev);
 137         return -ENOMEM;
 138 }
 139
 140 static void nf_tables_netdev_exit_net(struct net *net)
 141 {
 142         nft_unregister_afinfo(net, net->nft.netdev);
 143         kfree(net->nft.netdev);
 144 }
 145
 146 static struct pernet_operations nf_tables_netdev_net_ops = {
 147         .init   = nf_tables_netdev_init_net,
 148         .exit   = nf_tables_netdev_exit_net,
 149 };
 150
 151 static const struct nf_chain_type nft_filter_chain_netdev = {
 152         .name           = "filter",
 153         .type           = NFT_CHAIN_T_DEFAULT,
 154         .family         = NFPROTO_NETDEV,
 155         .owner          = THIS_MODULE,
 156         .hook_mask      = (1 << NF_NETDEV_INGRESS),
 157 };
 158
 159 static void nft_netdev_event(unsigned long event, struct net_device *dev,
 160                              struct nft_ctx *ctx)
 161 {
 162         struct nft_base_chain *basechain = nft_base_chain(ctx->chain);
 163
 164         switch (event) {
 165         case NETDEV_UNREGISTER:
 166                 if (strcmp(basechain->dev_name, dev->name) != 0)
 167                         return;
 168
 169                 __nft_release_basechain(ctx);
 170                 break;
 171         case NETDEV_CHANGENAME:
 172                 if (dev->ifindex != basechain->ops[0].dev->ifindex)
 173                         return;
 174
 175                 strncpy(basechain->dev_name, dev->name, IFNAMSIZ);
 176                 break;
 177         }
 178 }
 179
 180 static int nf_tables_netdev_event(struct notifier_block *this,
 181                                   unsigned long event, void *ptr)
 182 {
 183         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 184         struct nft_af_info *afi;
 185         struct nft_table *table;
 186         struct nft_chain *chain, *nr;
 187         struct nft_ctx ctx = {
 188                 .net    = dev_net(dev),
 189         };
 190
 191         if (event != NETDEV_UNREGISTER &&
 192             event != NETDEV_CHANGENAME)
 193                 return NOTIFY_DONE;
 194
 195         nfnl_lock(NFNL_SUBSYS_NFTABLES);
 196         list_for_each_entry(afi, &dev_net(dev)->nft.af_info, list) {
 197                 ctx.afi = afi;
 198                 if (afi->family != NFPROTO_NETDEV)
 199                         continue;
 200
 201                 list_for_each_entry(table, &afi->tables, list) {
 202                         ctx.table = table;
 203                         list_for_each_entry_safe(chain, nr, &table->chains, list) {
 204                                 if (!(chain->flags & NFT_BASE_CHAIN))
 205                                         continue;
 206
 207                                 ctx.chain = chain;
 208                                 nft_netdev_event(event, dev, &ctx);
 209                         }
 210                 }
 211         }
 212         nfnl_unlock(NFNL_SUBSYS_NFTABLES);
 213
 214         return NOTIFY_DONE;
 215 }
 216
 217 static struct notifier_block nf_tables_netdev_notifier = {
 218         .notifier_call  = nf_tables_netdev_event,
 219 };
 220
 221 static int __init nf_tables_netdev_init(void)
 222 {
 223         int ret;
 224
 225         nft_register_chain_type(&nft_filter_chain_netdev);
 226         ret = register_pernet_subsys(&nf_tables_netdev_net_ops);
 227         if (ret < 0) {
 228                 nft_unregister_chain_type(&nft_filter_chain_netdev);
 229                 return ret;
 230         }
 231         register_netdevice_notifier(&nf_tables_netdev_notifier);
 232         return 0;
 233 }
 234
 235 static void __exit nf_tables_netdev_exit(void)
 236 {
 237         unregister_netdevice_notifier(&nf_tables_netdev_notifier);
 238         unregister_pernet_subsys(&nf_tables_netdev_net_ops);
 239         nft_unregister_chain_type(&nft_filter_chain_netdev);
 240 }
 241
 242 module_init(nf_tables_netdev_init);
 243 module_exit(nf_tables_netdev_exit);
 244
 245 MODULE_LICENSE("GPL");
 246 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 247 MODULE_ALIAS_NFT_FAMILY(5); /* NFPROTO_NETDEV */