1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Handle firewalling 4 * Linux ethernet bridge 5 * 6 * Authors: 7 * Lennert Buytenhek <buytenh@gnu.org> 8 * Bart De Schuymer <bdschuym@pandora.be> 9 * 10 * Lennert dedicates this file to Kerstin Wurdinger. 11 */ 12 13 #include <linux/module.h> 14 #include <linux/kernel.h> 15 #include <linux/slab.h> 16 #include <linux/ip.h> 17 #include <linux/netdevice.h> 18 #include <linux/skbuff.h> 19 #include <linux/if_arp.h> 20 #include <linux/if_ether.h> 21 #include <linux/if_vlan.h> 22 #include <linux/if_pppox.h> 23 #include <linux/ppp_defs.h> 24 #include <linux/netfilter_bridge.h> 25 #include <linux/netfilter_ipv4.h> 26 #include <linux/netfilter_ipv6.h> 27 #include <linux/netfilter_arp.h> 28 #include <linux/in_route.h> 29 #include <linux/inetdevice.h> 30 31 #include <net/ip.h> 32 #include <net/ipv6.h> 33 #include <net/addrconf.h> 34 #include <net/route.h> 35 #include <net/netfilter/br_netfilter.h> 36 37 #include <linux/uaccess.h> 38 #include "br_private.h" 39 #ifdef CONFIG_SYSCTL 40 #include <linux/sysctl.h> 41 #endif 42 43 int br_validate_ipv6(struct net *net, struct sk_buff *skb) 44 { 45 const struct ipv6hdr *hdr; 46 struct inet6_dev *idev = __in6_dev_get(skb->dev); 47 u32 pkt_len; 48 u8 ip6h_len = sizeof(struct ipv6hdr); 49 50 if (!pskb_may_pull(skb, ip6h_len)) 51 goto inhdr_error; 52 53 if (skb->len < ip6h_len) 54 goto drop; 55 56 hdr = ipv6_hdr(skb); 57 58 if (hdr->version != 6) 59 goto inhdr_error; 60 61 pkt_len = ntohs(hdr->payload_len); 62 if (hdr->nexthdr == NEXTHDR_HOP && nf_ip6_check_hbh_len(skb, &pkt_len)) 63 goto drop; 64 65 if (pkt_len + ip6h_len > skb->len) { 66 __IP6_INC_STATS(net, idev, 67 IPSTATS_MIB_INTRUNCATEDPKTS); 68 goto drop; 69 } 70 if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) { 71 __IP6_INC_STATS(net, idev, 72 IPSTATS_MIB_INDISCARDS); 73 goto drop; 74 } 75 76 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); 77 /* No IP options in IPv6 header; however it should be 78 * checked if some next headers need special treatment 79 */ 80 return 0; 81 82 inhdr_error: 83 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 84 drop: 85 return -1; 86 } 87 88 static inline bool 89 br_nf_ipv6_daddr_was_changed(const struct sk_buff *skb, 90 const struct nf_bridge_info *nf_bridge) 91 { 92 return memcmp(&nf_bridge->ipv6_daddr, &ipv6_hdr(skb)->daddr, 93 sizeof(ipv6_hdr(skb)->daddr)) != 0; 94 } 95 96 /* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables 97 * PREROUTING and continue the bridge PRE_ROUTING hook. See comment 98 * for br_nf_pre_routing_finish(), same logic is used here but 99 * equivalent IPv6 function ip6_route_input() called indirectly. 100 */ 101 static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struct sk_buff *skb) 102 { 103 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 104 struct rtable *rt; 105 struct net_device *dev = skb->dev; 106 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops(); 107 108 nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size; 109 110 if (nf_bridge->pkt_otherhost) { 111 skb->pkt_type = PACKET_OTHERHOST; 112 nf_bridge->pkt_otherhost = false; 113 } 114 nf_bridge->in_prerouting = 0; 115 if (br_nf_ipv6_daddr_was_changed(skb, nf_bridge)) { 116 skb_dst_drop(skb); 117 v6ops->route_input(skb); 118 119 if (skb_dst(skb)->error) { 120 kfree_skb(skb); 121 return 0; 122 } 123 124 if (skb_dst(skb)->dev == dev) { 125 skb->dev = nf_bridge->physindev; 126 nf_bridge_update_protocol(skb); 127 nf_bridge_push_encap_header(skb); 128 br_nf_hook_thresh(NF_BR_PRE_ROUTING, 129 net, sk, skb, skb->dev, NULL, 130 br_nf_pre_routing_finish_bridge); 131 return 0; 132 } 133 ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr); 134 skb->pkt_type = PACKET_HOST; 135 } else { 136 rt = bridge_parent_rtable(nf_bridge->physindev); 137 if (!rt) { 138 kfree_skb(skb); 139 return 0; 140 } 141 skb_dst_drop(skb); 142 skb_dst_set_noref(skb, &rt->dst); 143 } 144 145 skb->dev = nf_bridge->physindev; 146 nf_bridge_update_protocol(skb); 147 nf_bridge_push_encap_header(skb); 148 br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, 149 skb->dev, NULL, br_handle_frame_finish); 150 151 return 0; 152 } 153 154 /* Replicate the checks that IPv6 does on packet reception and pass the packet 155 * to ip6tables. 156 */ 157 unsigned int br_nf_pre_routing_ipv6(void *priv, 158 struct sk_buff *skb, 159 const struct nf_hook_state *state) 160 { 161 struct nf_bridge_info *nf_bridge; 162 163 if (br_validate_ipv6(state->net, skb)) 164 return NF_DROP_REASON(skb, SKB_DROP_REASON_IP_INHDR, 0); 165 166 nf_bridge = nf_bridge_alloc(skb); 167 if (!nf_bridge) 168 return NF_DROP_REASON(skb, SKB_DROP_REASON_NOMEM, 0); 169 if (!setup_pre_routing(skb, state->net)) 170 return NF_DROP_REASON(skb, SKB_DROP_REASON_DEV_READY, 0); 171 172 nf_bridge = nf_bridge_info_get(skb); 173 nf_bridge->ipv6_daddr = ipv6_hdr(skb)->daddr; 174 175 skb->protocol = htons(ETH_P_IPV6); 176 skb->transport_header = skb->network_header + sizeof(struct ipv6hdr); 177 178 NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->net, state->sk, skb, 179 skb->dev, NULL, 180 br_nf_pre_routing_finish_ipv6); 181 182 return NF_STOLEN; 183 } 184