| 1 | /* |
| 2 | * Handle firewalling |
| 3 | * Linux ethernet bridge |
| 4 | * |
| 5 | * Authors: |
| 6 | * Lennert Buytenhek <buytenh@gnu.org> |
| 7 | * Bart De Schuymer <bdschuym@pandora.be> |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or |
| 10 | * modify it under the terms of the GNU General Public License |
| 11 | * as published by the Free Software Foundation; either version |
| 12 | * 2 of the License, or (at your option) any later version. |
| 13 | * |
| 14 | * Lennert dedicates this file to Kerstin Wurdinger. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/kernel.h> |
| 19 | #include <linux/slab.h> |
| 20 | #include <linux/ip.h> |
| 21 | #include <linux/netdevice.h> |
| 22 | #include <linux/skbuff.h> |
| 23 | #include <linux/if_arp.h> |
| 24 | #include <linux/if_ether.h> |
| 25 | #include <linux/if_vlan.h> |
| 26 | #include <linux/if_pppox.h> |
| 27 | #include <linux/ppp_defs.h> |
| 28 | #include <linux/netfilter_bridge.h> |
| 29 | #include <linux/netfilter_ipv4.h> |
| 30 | #include <linux/netfilter_ipv6.h> |
| 31 | #include <linux/netfilter_arp.h> |
| 32 | #include <linux/in_route.h> |
| 33 | #include <linux/inetdevice.h> |
| 34 | |
| 35 | #include <net/ip.h> |
| 36 | #include <net/ipv6.h> |
| 37 | #include <net/addrconf.h> |
| 38 | #include <net/route.h> |
| 39 | #include <net/netfilter/br_netfilter.h> |
| 40 | |
| 41 | #include <asm/uaccess.h> |
| 42 | #include "br_private.h" |
| 43 | #ifdef CONFIG_SYSCTL |
| 44 | #include <linux/sysctl.h> |
| 45 | #endif |
| 46 | |
| 47 | /* We only check the length. A bridge shouldn't do any hop-by-hop stuff |
| 48 | * anyway |
| 49 | */ |
| 50 | static int br_nf_check_hbh_len(struct sk_buff *skb) |
| 51 | { |
| 52 | unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1); |
| 53 | u32 pkt_len; |
| 54 | const unsigned char *nh = skb_network_header(skb); |
| 55 | int off = raw - nh; |
| 56 | int len = (raw[1] + 1) << 3; |
| 57 | |
| 58 | if ((raw + len) - skb->data > skb_headlen(skb)) |
| 59 | goto bad; |
| 60 | |
| 61 | off += 2; |
| 62 | len -= 2; |
| 63 | |
| 64 | while (len > 0) { |
| 65 | int optlen = nh[off + 1] + 2; |
| 66 | |
| 67 | switch (nh[off]) { |
| 68 | case IPV6_TLV_PAD1: |
| 69 | optlen = 1; |
| 70 | break; |
| 71 | |
| 72 | case IPV6_TLV_PADN: |
| 73 | break; |
| 74 | |
| 75 | case IPV6_TLV_JUMBO: |
| 76 | if (nh[off + 1] != 4 || (off & 3) != 2) |
| 77 | goto bad; |
| 78 | pkt_len = ntohl(*(__be32 *)(nh + off + 2)); |
| 79 | if (pkt_len <= IPV6_MAXPLEN || |
| 80 | ipv6_hdr(skb)->payload_len) |
| 81 | goto bad; |
| 82 | if (pkt_len > skb->len - sizeof(struct ipv6hdr)) |
| 83 | goto bad; |
| 84 | if (pskb_trim_rcsum(skb, |
| 85 | pkt_len + sizeof(struct ipv6hdr))) |
| 86 | goto bad; |
| 87 | nh = skb_network_header(skb); |
| 88 | break; |
| 89 | default: |
| 90 | if (optlen > len) |
| 91 | goto bad; |
| 92 | break; |
| 93 | } |
| 94 | off += optlen; |
| 95 | len -= optlen; |
| 96 | } |
| 97 | if (len == 0) |
| 98 | return 0; |
| 99 | bad: |
| 100 | return -1; |
| 101 | } |
| 102 | |
| 103 | int br_validate_ipv6(struct net *net, struct sk_buff *skb) |
| 104 | { |
| 105 | const struct ipv6hdr *hdr; |
| 106 | struct inet6_dev *idev = __in6_dev_get(skb->dev); |
| 107 | u32 pkt_len; |
| 108 | u8 ip6h_len = sizeof(struct ipv6hdr); |
| 109 | |
| 110 | if (!pskb_may_pull(skb, ip6h_len)) |
| 111 | goto inhdr_error; |
| 112 | |
| 113 | if (skb->len < ip6h_len) |
| 114 | goto drop; |
| 115 | |
| 116 | hdr = ipv6_hdr(skb); |
| 117 | |
| 118 | if (hdr->version != 6) |
| 119 | goto inhdr_error; |
| 120 | |
| 121 | pkt_len = ntohs(hdr->payload_len); |
| 122 | |
| 123 | if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { |
| 124 | if (pkt_len + ip6h_len > skb->len) { |
| 125 | IP6_INC_STATS_BH(net, idev, |
| 126 | IPSTATS_MIB_INTRUNCATEDPKTS); |
| 127 | goto drop; |
| 128 | } |
| 129 | if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) { |
| 130 | IP6_INC_STATS_BH(net, idev, |
| 131 | IPSTATS_MIB_INDISCARDS); |
| 132 | goto drop; |
| 133 | } |
| 134 | } |
| 135 | if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb)) |
| 136 | goto drop; |
| 137 | |
| 138 | memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); |
| 139 | /* No IP options in IPv6 header; however it should be |
| 140 | * checked if some next headers need special treatment |
| 141 | */ |
| 142 | return 0; |
| 143 | |
| 144 | inhdr_error: |
| 145 | IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); |
| 146 | drop: |
| 147 | return -1; |
| 148 | } |
| 149 | |
| 150 | static inline bool |
| 151 | br_nf_ipv6_daddr_was_changed(const struct sk_buff *skb, |
| 152 | const struct nf_bridge_info *nf_bridge) |
| 153 | { |
| 154 | return memcmp(&nf_bridge->ipv6_daddr, &ipv6_hdr(skb)->daddr, |
| 155 | sizeof(ipv6_hdr(skb)->daddr)) != 0; |
| 156 | } |
| 157 | |
| 158 | /* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables |
| 159 | * PREROUTING and continue the bridge PRE_ROUTING hook. See comment |
| 160 | * for br_nf_pre_routing_finish(), same logic is used here but |
| 161 | * equivalent IPv6 function ip6_route_input() called indirectly. |
| 162 | */ |
| 163 | static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 164 | { |
| 165 | struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); |
| 166 | struct rtable *rt; |
| 167 | struct net_device *dev = skb->dev; |
| 168 | const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops(); |
| 169 | |
| 170 | nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size; |
| 171 | |
| 172 | if (nf_bridge->pkt_otherhost) { |
| 173 | skb->pkt_type = PACKET_OTHERHOST; |
| 174 | nf_bridge->pkt_otherhost = false; |
| 175 | } |
| 176 | nf_bridge->in_prerouting = 0; |
| 177 | if (br_nf_ipv6_daddr_was_changed(skb, nf_bridge)) { |
| 178 | skb_dst_drop(skb); |
| 179 | v6ops->route_input(skb); |
| 180 | |
| 181 | if (skb_dst(skb)->error) { |
| 182 | kfree_skb(skb); |
| 183 | return 0; |
| 184 | } |
| 185 | |
| 186 | if (skb_dst(skb)->dev == dev) { |
| 187 | skb->dev = nf_bridge->physindev; |
| 188 | nf_bridge_update_protocol(skb); |
| 189 | nf_bridge_push_encap_header(skb); |
| 190 | NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, |
| 191 | net, sk, skb, skb->dev, NULL, |
| 192 | br_nf_pre_routing_finish_bridge, |
| 193 | 1); |
| 194 | return 0; |
| 195 | } |
| 196 | ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr); |
| 197 | skb->pkt_type = PACKET_HOST; |
| 198 | } else { |
| 199 | rt = bridge_parent_rtable(nf_bridge->physindev); |
| 200 | if (!rt) { |
| 201 | kfree_skb(skb); |
| 202 | return 0; |
| 203 | } |
| 204 | skb_dst_set_noref(skb, &rt->dst); |
| 205 | } |
| 206 | |
| 207 | skb->dev = nf_bridge->physindev; |
| 208 | nf_bridge_update_protocol(skb); |
| 209 | nf_bridge_push_encap_header(skb); |
| 210 | NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, net, sk, skb, |
| 211 | skb->dev, NULL, |
| 212 | br_handle_frame_finish, 1); |
| 213 | |
| 214 | return 0; |
| 215 | } |
| 216 | |
| 217 | /* Replicate the checks that IPv6 does on packet reception and pass the packet |
| 218 | * to ip6tables. |
| 219 | */ |
| 220 | unsigned int br_nf_pre_routing_ipv6(void *priv, |
| 221 | struct sk_buff *skb, |
| 222 | const struct nf_hook_state *state) |
| 223 | { |
| 224 | struct nf_bridge_info *nf_bridge; |
| 225 | |
| 226 | if (br_validate_ipv6(state->net, skb)) |
| 227 | return NF_DROP; |
| 228 | |
| 229 | nf_bridge_put(skb->nf_bridge); |
| 230 | if (!nf_bridge_alloc(skb)) |
| 231 | return NF_DROP; |
| 232 | if (!setup_pre_routing(skb)) |
| 233 | return NF_DROP; |
| 234 | |
| 235 | nf_bridge = nf_bridge_info_get(skb); |
| 236 | nf_bridge->ipv6_daddr = ipv6_hdr(skb)->daddr; |
| 237 | |
| 238 | skb->protocol = htons(ETH_P_IPV6); |
| 239 | NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->net, state->sk, skb, |
| 240 | skb->dev, NULL, |
| 241 | br_nf_pre_routing_finish_ipv6); |
| 242 | |
| 243 | return NF_STOLEN; |
| 244 | } |