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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
230ac490 PNA |
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 | * | |
230ac490 PNA |
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 | ||
7c0f6ba6 | 37 | #include <linux/uaccess.h> |
230ac490 PNA |
38 | #include "br_private.h" |
39 | #ifdef CONFIG_SYSCTL | |
40 | #include <linux/sysctl.h> | |
41 | #endif | |
42 | ||
43 | /* We only check the length. A bridge shouldn't do any hop-by-hop stuff | |
44 | * anyway | |
45 | */ | |
46 | static int br_nf_check_hbh_len(struct sk_buff *skb) | |
47 | { | |
48 | unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1); | |
49 | u32 pkt_len; | |
50 | const unsigned char *nh = skb_network_header(skb); | |
51 | int off = raw - nh; | |
52 | int len = (raw[1] + 1) << 3; | |
53 | ||
54 | if ((raw + len) - skb->data > skb_headlen(skb)) | |
55 | goto bad; | |
56 | ||
57 | off += 2; | |
58 | len -= 2; | |
59 | ||
60 | while (len > 0) { | |
61 | int optlen = nh[off + 1] + 2; | |
62 | ||
63 | switch (nh[off]) { | |
64 | case IPV6_TLV_PAD1: | |
65 | optlen = 1; | |
66 | break; | |
67 | ||
68 | case IPV6_TLV_PADN: | |
69 | break; | |
70 | ||
71 | case IPV6_TLV_JUMBO: | |
72 | if (nh[off + 1] != 4 || (off & 3) != 2) | |
73 | goto bad; | |
74 | pkt_len = ntohl(*(__be32 *)(nh + off + 2)); | |
75 | if (pkt_len <= IPV6_MAXPLEN || | |
76 | ipv6_hdr(skb)->payload_len) | |
77 | goto bad; | |
78 | if (pkt_len > skb->len - sizeof(struct ipv6hdr)) | |
79 | goto bad; | |
80 | if (pskb_trim_rcsum(skb, | |
81 | pkt_len + sizeof(struct ipv6hdr))) | |
82 | goto bad; | |
83 | nh = skb_network_header(skb); | |
84 | break; | |
85 | default: | |
86 | if (optlen > len) | |
87 | goto bad; | |
88 | break; | |
89 | } | |
90 | off += optlen; | |
91 | len -= optlen; | |
92 | } | |
93 | if (len == 0) | |
94 | return 0; | |
95 | bad: | |
96 | return -1; | |
97 | } | |
98 | ||
c1444c63 | 99 | int br_validate_ipv6(struct net *net, struct sk_buff *skb) |
230ac490 PNA |
100 | { |
101 | const struct ipv6hdr *hdr; | |
86e89718 | 102 | struct inet6_dev *idev = __in6_dev_get(skb->dev); |
230ac490 PNA |
103 | u32 pkt_len; |
104 | u8 ip6h_len = sizeof(struct ipv6hdr); | |
105 | ||
106 | if (!pskb_may_pull(skb, ip6h_len)) | |
107 | goto inhdr_error; | |
108 | ||
109 | if (skb->len < ip6h_len) | |
110 | goto drop; | |
111 | ||
112 | hdr = ipv6_hdr(skb); | |
113 | ||
114 | if (hdr->version != 6) | |
115 | goto inhdr_error; | |
116 | ||
117 | pkt_len = ntohs(hdr->payload_len); | |
118 | ||
119 | if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { | |
120 | if (pkt_len + ip6h_len > skb->len) { | |
1d015503 ED |
121 | __IP6_INC_STATS(net, idev, |
122 | IPSTATS_MIB_INTRUNCATEDPKTS); | |
230ac490 PNA |
123 | goto drop; |
124 | } | |
125 | if (pskb_trim_rcsum(skb, pkt_len + ip6h_len)) { | |
1d015503 ED |
126 | __IP6_INC_STATS(net, idev, |
127 | IPSTATS_MIB_INDISCARDS); | |
230ac490 PNA |
128 | goto drop; |
129 | } | |
6c57f045 | 130 | hdr = ipv6_hdr(skb); |
230ac490 PNA |
131 | } |
132 | if (hdr->nexthdr == NEXTHDR_HOP && br_nf_check_hbh_len(skb)) | |
133 | goto drop; | |
134 | ||
135 | memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); | |
136 | /* No IP options in IPv6 header; however it should be | |
137 | * checked if some next headers need special treatment | |
138 | */ | |
139 | return 0; | |
140 | ||
141 | inhdr_error: | |
1d015503 | 142 | __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); |
230ac490 PNA |
143 | drop: |
144 | return -1; | |
145 | } | |
146 | ||
147 | static inline bool | |
148 | br_nf_ipv6_daddr_was_changed(const struct sk_buff *skb, | |
149 | const struct nf_bridge_info *nf_bridge) | |
150 | { | |
151 | return memcmp(&nf_bridge->ipv6_daddr, &ipv6_hdr(skb)->daddr, | |
152 | sizeof(ipv6_hdr(skb)->daddr)) != 0; | |
153 | } | |
154 | ||
155 | /* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables | |
156 | * PREROUTING and continue the bridge PRE_ROUTING hook. See comment | |
157 | * for br_nf_pre_routing_finish(), same logic is used here but | |
158 | * equivalent IPv6 function ip6_route_input() called indirectly. | |
159 | */ | |
0c4b51f0 | 160 | static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struct sk_buff *skb) |
230ac490 PNA |
161 | { |
162 | struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); | |
163 | struct rtable *rt; | |
164 | struct net_device *dev = skb->dev; | |
165 | const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops(); | |
166 | ||
167 | nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size; | |
168 | ||
169 | if (nf_bridge->pkt_otherhost) { | |
170 | skb->pkt_type = PACKET_OTHERHOST; | |
171 | nf_bridge->pkt_otherhost = false; | |
172 | } | |
72b1e5e4 | 173 | nf_bridge->in_prerouting = 0; |
230ac490 PNA |
174 | if (br_nf_ipv6_daddr_was_changed(skb, nf_bridge)) { |
175 | skb_dst_drop(skb); | |
176 | v6ops->route_input(skb); | |
177 | ||
178 | if (skb_dst(skb)->error) { | |
179 | kfree_skb(skb); | |
180 | return 0; | |
181 | } | |
182 | ||
183 | if (skb_dst(skb)->dev == dev) { | |
184 | skb->dev = nf_bridge->physindev; | |
185 | nf_bridge_update_protocol(skb); | |
186 | nf_bridge_push_encap_header(skb); | |
c5136b15 FW |
187 | br_nf_hook_thresh(NF_BR_PRE_ROUTING, |
188 | net, sk, skb, skb->dev, NULL, | |
189 | br_nf_pre_routing_finish_bridge); | |
230ac490 PNA |
190 | return 0; |
191 | } | |
192 | ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr); | |
193 | skb->pkt_type = PACKET_HOST; | |
194 | } else { | |
195 | rt = bridge_parent_rtable(nf_bridge->physindev); | |
196 | if (!rt) { | |
197 | kfree_skb(skb); | |
198 | return 0; | |
199 | } | |
200 | skb_dst_set_noref(skb, &rt->dst); | |
201 | } | |
202 | ||
203 | skb->dev = nf_bridge->physindev; | |
204 | nf_bridge_update_protocol(skb); | |
205 | nf_bridge_push_encap_header(skb); | |
c5136b15 FW |
206 | br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, |
207 | skb->dev, NULL, br_handle_frame_finish); | |
230ac490 PNA |
208 | |
209 | return 0; | |
210 | } | |
211 | ||
212 | /* Replicate the checks that IPv6 does on packet reception and pass the packet | |
213 | * to ip6tables. | |
214 | */ | |
06198b34 | 215 | unsigned int br_nf_pre_routing_ipv6(void *priv, |
230ac490 PNA |
216 | struct sk_buff *skb, |
217 | const struct nf_hook_state *state) | |
218 | { | |
219 | struct nf_bridge_info *nf_bridge; | |
220 | ||
c1444c63 | 221 | if (br_validate_ipv6(state->net, skb)) |
230ac490 PNA |
222 | return NF_DROP; |
223 | ||
de8bda1d FW |
224 | nf_bridge = nf_bridge_alloc(skb); |
225 | if (!nf_bridge) | |
230ac490 | 226 | return NF_DROP; |
ff6d090d | 227 | if (!setup_pre_routing(skb, state->net)) |
230ac490 PNA |
228 | return NF_DROP; |
229 | ||
230 | nf_bridge = nf_bridge_info_get(skb); | |
231 | nf_bridge->ipv6_daddr = ipv6_hdr(skb)->daddr; | |
232 | ||
233 | skb->protocol = htons(ETH_P_IPV6); | |
e166e4fd XL |
234 | skb->transport_header = skb->network_header + sizeof(struct ipv6hdr); |
235 | ||
29a26a56 | 236 | NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->net, state->sk, skb, |
230ac490 PNA |
237 | skb->dev, NULL, |
238 | br_nf_pre_routing_finish_ipv6); | |
239 | ||
240 | return NF_STOLEN; | |
241 | } |