1// SPDX-License-Identifier: GPL-2.0
2#include <linux/kernel.h>
3#include <linux/netfilter.h>
4#include <linux/netfilter_ipv4.h>
5#include <linux/netfilter_ipv6.h>
6#include <net/netfilter/nf_queue.h>
7#include <net/ip6_checksum.h>
8
9#ifdef CONFIG_INET
10__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
11 unsigned int dataoff, u8 protocol)
12{
13 const struct iphdr *iph = ip_hdr(skb);
14 __sum16 csum = 0;
15
16 switch (skb->ip_summed) {
17 case CHECKSUM_COMPLETE:
18 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
19 break;
20 if ((protocol != IPPROTO_TCP && protocol != IPPROTO_UDP &&
21 !csum_fold(sum: skb->csum)) ||
22 !csum_tcpudp_magic(saddr: iph->saddr, daddr: iph->daddr,
23 len: skb->len - dataoff, proto: protocol,
24 sum: skb->csum)) {
25 skb->ip_summed = CHECKSUM_UNNECESSARY;
26 break;
27 }
28 fallthrough;
29 case CHECKSUM_NONE:
30 if (protocol != IPPROTO_TCP && protocol != IPPROTO_UDP)
31 skb->csum = 0;
32 else
33 skb->csum = csum_tcpudp_nofold(saddr: iph->saddr, daddr: iph->daddr,
34 len: skb->len - dataoff,
35 proto: protocol, sum: 0);
36 csum = __skb_checksum_complete(skb);
37 }
38 return csum;
39}
40EXPORT_SYMBOL(nf_ip_checksum);
41#endif
42
43static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
44 unsigned int dataoff, unsigned int len,
45 u8 protocol)
46{
47 const struct iphdr *iph = ip_hdr(skb);
48 __sum16 csum = 0;
49
50 switch (skb->ip_summed) {
51 case CHECKSUM_COMPLETE:
52 if (len == skb->len - dataoff)
53 return nf_ip_checksum(skb, hook, dataoff, protocol);
54 fallthrough;
55 case CHECKSUM_NONE:
56 skb->csum = csum_tcpudp_nofold(saddr: iph->saddr, daddr: iph->daddr, len: protocol,
57 proto: skb->len - dataoff, sum: 0);
58 skb->ip_summed = CHECKSUM_NONE;
59 return __skb_checksum_complete_head(skb, len: dataoff + len);
60 }
61 return csum;
62}
63
64__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
65 unsigned int dataoff, u8 protocol)
66{
67 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
68 __sum16 csum = 0;
69
70 switch (skb->ip_summed) {
71 case CHECKSUM_COMPLETE:
72 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
73 break;
74 if (!csum_ipv6_magic(saddr: &ip6h->saddr, daddr: &ip6h->daddr,
75 len: skb->len - dataoff, proto: protocol,
76 sum: csum_sub(csum: skb->csum,
77 addend: skb_checksum(skb, offset: 0,
78 len: dataoff, csum: 0)))) {
79 skb->ip_summed = CHECKSUM_UNNECESSARY;
80 break;
81 }
82 fallthrough;
83 case CHECKSUM_NONE:
84 skb->csum = ~csum_unfold(
85 n: csum_ipv6_magic(saddr: &ip6h->saddr, daddr: &ip6h->daddr,
86 len: skb->len - dataoff,
87 proto: protocol,
88 sum: csum_sub(csum: 0,
89 addend: skb_checksum(skb, offset: 0,
90 len: dataoff, csum: 0))));
91 csum = __skb_checksum_complete(skb);
92 }
93 return csum;
94}
95EXPORT_SYMBOL(nf_ip6_checksum);
96
97static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
98 unsigned int dataoff, unsigned int len,
99 u8 protocol)
100{
101 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
102 __wsum hsum;
103 __sum16 csum = 0;
104
105 switch (skb->ip_summed) {
106 case CHECKSUM_COMPLETE:
107 if (len == skb->len - dataoff)
108 return nf_ip6_checksum(skb, hook, dataoff, protocol);
109 fallthrough;
110 case CHECKSUM_NONE:
111 hsum = skb_checksum(skb, offset: 0, len: dataoff, csum: 0);
112 skb->csum = ~csum_unfold(n: csum_ipv6_magic(saddr: &ip6h->saddr,
113 daddr: &ip6h->daddr,
114 len: skb->len - dataoff,
115 proto: protocol,
116 sum: csum_sub(csum: 0, addend: hsum)));
117 skb->ip_summed = CHECKSUM_NONE;
118 return __skb_checksum_complete_head(skb, len: dataoff + len);
119 }
120 return csum;
121};
122
123__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
124 unsigned int dataoff, u8 protocol,
125 unsigned short family)
126{
127 __sum16 csum = 0;
128
129 switch (family) {
130 case AF_INET:
131 csum = nf_ip_checksum(skb, hook, dataoff, protocol);
132 break;
133 case AF_INET6:
134 csum = nf_ip6_checksum(skb, hook, dataoff, protocol);
135 break;
136 }
137
138 return csum;
139}
140EXPORT_SYMBOL_GPL(nf_checksum);
141
142__sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
143 unsigned int dataoff, unsigned int len,
144 u8 protocol, unsigned short family)
145{
146 __sum16 csum = 0;
147
148 switch (family) {
149 case AF_INET:
150 csum = nf_ip_checksum_partial(skb, hook, dataoff, len,
151 protocol);
152 break;
153 case AF_INET6:
154 csum = nf_ip6_checksum_partial(skb, hook, dataoff, len,
155 protocol);
156 break;
157 }
158
159 return csum;
160}
161EXPORT_SYMBOL_GPL(nf_checksum_partial);
162
163int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
164 bool strict, unsigned short family)
165{
166 const struct nf_ipv6_ops *v6ops __maybe_unused;
167 int ret = 0;
168
169 switch (family) {
170 case AF_INET:
171 ret = nf_ip_route(net, dst, fl, strict);
172 break;
173 case AF_INET6:
174 ret = nf_ip6_route(net, dst, fl, strict);
175 break;
176 }
177
178 return ret;
179}
180EXPORT_SYMBOL_GPL(nf_route);
181
182static int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry)
183{
184#ifdef CONFIG_INET
185 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
186
187 if (entry->state.hook == NF_INET_LOCAL_OUT) {
188 const struct iphdr *iph = ip_hdr(skb);
189
190 if (!(iph->tos == rt_info->tos &&
191 skb->mark == rt_info->mark &&
192 iph->daddr == rt_info->daddr &&
193 iph->saddr == rt_info->saddr))
194 return ip_route_me_harder(net: entry->state.net, sk: entry->state.sk,
195 skb, addr_type: RTN_UNSPEC);
196 }
197#endif
198 return 0;
199}
200
201int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry)
202{
203 const struct nf_ipv6_ops *v6ops;
204 int ret = 0;
205
206 switch (entry->state.pf) {
207 case AF_INET:
208 ret = nf_ip_reroute(skb, entry);
209 break;
210 case AF_INET6:
211 v6ops = rcu_dereference(nf_ipv6_ops);
212 if (v6ops)
213 ret = v6ops->reroute(skb, entry);
214 break;
215 }
216 return ret;
217}
218
219/* Only get and check the lengths, not do any hop-by-hop stuff. */
220int nf_ip6_check_hbh_len(struct sk_buff *skb, u32 *plen)
221{
222 int len, off = sizeof(struct ipv6hdr);
223 unsigned char *nh;
224
225 if (!pskb_may_pull(skb, len: off + 8))
226 return -ENOMEM;
227 nh = (unsigned char *)(ipv6_hdr(skb) + 1);
228 len = (nh[1] + 1) << 3;
229
230 if (!pskb_may_pull(skb, len: off + len))
231 return -ENOMEM;
232 nh = skb_network_header(skb);
233
234 off += 2;
235 len -= 2;
236 while (len > 0) {
237 int optlen;
238
239 if (nh[off] == IPV6_TLV_PAD1) {
240 off++;
241 len--;
242 continue;
243 }
244 if (len < 2)
245 return -EBADMSG;
246 optlen = nh[off + 1] + 2;
247 if (optlen > len)
248 return -EBADMSG;
249
250 if (nh[off] == IPV6_TLV_JUMBO) {
251 u32 pkt_len;
252
253 if (nh[off + 1] != 4 || (off & 3) != 2)
254 return -EBADMSG;
255 pkt_len = ntohl(*(__be32 *)(nh + off + 2));
256 if (pkt_len <= IPV6_MAXPLEN ||
257 ipv6_hdr(skb)->payload_len)
258 return -EBADMSG;
259 if (pkt_len > skb->len - sizeof(struct ipv6hdr))
260 return -EBADMSG;
261 *plen = pkt_len;
262 }
263 off += optlen;
264 len -= optlen;
265 }
266
267 return len ? -EBADMSG : 0;
268}
269EXPORT_SYMBOL_GPL(nf_ip6_check_hbh_len);
270

source code of linux/net/netfilter/utils.c