1/*
2 * IPv6 library code, needed by static components when full IPv6 support is
3 * not configured or static.  These functions are needed by GSO/GRO implementation.
4 */
5#include <linux/export.h>
6#include <net/ip.h>
7#include <net/ipv6.h>
8#include <net/ip6_fib.h>
9#include <net/addrconf.h>
10#include <net/secure_seq.h>
11
12static u32 __ipv6_select_ident(struct net *net, u32 hashrnd,
13			       struct in6_addr *dst, struct in6_addr *src)
14{
15	u32 hash, id;
16
17	hash = __ipv6_addr_jhash(dst, hashrnd);
18	hash = __ipv6_addr_jhash(src, hash);
19	hash ^= net_hash_mix(net);
20
21	/* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
22	 * set the hight order instead thus minimizing possible future
23	 * collisions.
24	 */
25	id = ip_idents_reserve(hash, 1);
26	if (unlikely(!id))
27		id = 1 << 31;
28
29	return id;
30}
31
32/* This function exists only for tap drivers that must support broken
33 * clients requesting UFO without specifying an IPv6 fragment ID.
34 *
35 * This is similar to ipv6_select_ident() but we use an independent hash
36 * seed to limit information leakage.
37 *
38 * The network header must be set before calling this.
39 */
40void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
41{
42	static u32 ip6_proxy_idents_hashrnd __read_mostly;
43	struct in6_addr buf[2];
44	struct in6_addr *addrs;
45	u32 id;
46
47	addrs = skb_header_pointer(skb,
48				   skb_network_offset(skb) +
49				   offsetof(struct ipv6hdr, saddr),
50				   sizeof(buf), buf);
51	if (!addrs)
52		return;
53
54	net_get_random_once(&ip6_proxy_idents_hashrnd,
55			    sizeof(ip6_proxy_idents_hashrnd));
56
57	id = __ipv6_select_ident(net, ip6_proxy_idents_hashrnd,
58				 &addrs[1], &addrs[0]);
59	skb_shinfo(skb)->ip6_frag_id = htonl(id);
60}
61EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
62
63void ipv6_select_ident(struct net *net, struct frag_hdr *fhdr,
64		       struct rt6_info *rt)
65{
66	static u32 ip6_idents_hashrnd __read_mostly;
67	u32 id;
68
69	net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
70
71	id = __ipv6_select_ident(net, ip6_idents_hashrnd, &rt->rt6i_dst.addr,
72				 &rt->rt6i_src.addr);
73	fhdr->identification = htonl(id);
74}
75EXPORT_SYMBOL(ipv6_select_ident);
76
77int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
78{
79	u16 offset = sizeof(struct ipv6hdr);
80	struct ipv6_opt_hdr *exthdr =
81				(struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
82	unsigned int packet_len = skb_tail_pointer(skb) -
83		skb_network_header(skb);
84	int found_rhdr = 0;
85	*nexthdr = &ipv6_hdr(skb)->nexthdr;
86
87	while (offset + 1 <= packet_len) {
88
89		switch (**nexthdr) {
90
91		case NEXTHDR_HOP:
92			break;
93		case NEXTHDR_ROUTING:
94			found_rhdr = 1;
95			break;
96		case NEXTHDR_DEST:
97#if IS_ENABLED(CONFIG_IPV6_MIP6)
98			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
99				break;
100#endif
101			if (found_rhdr)
102				return offset;
103			break;
104		default:
105			return offset;
106		}
107
108		offset += ipv6_optlen(exthdr);
109		*nexthdr = &exthdr->nexthdr;
110		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
111						 offset);
112	}
113
114	return offset;
115}
116EXPORT_SYMBOL(ip6_find_1stfragopt);
117
118#if IS_ENABLED(CONFIG_IPV6)
119int ip6_dst_hoplimit(struct dst_entry *dst)
120{
121	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
122	if (hoplimit == 0) {
123		struct net_device *dev = dst->dev;
124		struct inet6_dev *idev;
125
126		rcu_read_lock();
127		idev = __in6_dev_get(dev);
128		if (idev)
129			hoplimit = idev->cnf.hop_limit;
130		else
131			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
132		rcu_read_unlock();
133	}
134	return hoplimit;
135}
136EXPORT_SYMBOL(ip6_dst_hoplimit);
137#endif
138
139static int __ip6_local_out_sk(struct sock *sk, struct sk_buff *skb)
140{
141	int len;
142
143	len = skb->len - sizeof(struct ipv6hdr);
144	if (len > IPV6_MAXPLEN)
145		len = 0;
146	ipv6_hdr(skb)->payload_len = htons(len);
147	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
148
149	return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, sk, skb,
150		       NULL, skb_dst(skb)->dev, dst_output_sk);
151}
152
153int __ip6_local_out(struct sk_buff *skb)
154{
155	return __ip6_local_out_sk(skb->sk, skb);
156}
157EXPORT_SYMBOL_GPL(__ip6_local_out);
158
159int ip6_local_out_sk(struct sock *sk, struct sk_buff *skb)
160{
161	int err;
162
163	err = __ip6_local_out_sk(sk, skb);
164	if (likely(err == 1))
165		err = dst_output_sk(sk, skb);
166
167	return err;
168}
169EXPORT_SYMBOL_GPL(ip6_local_out_sk);
170
171int ip6_local_out(struct sk_buff *skb)
172{
173	return ip6_local_out_sk(skb->sk, skb);
174}
175EXPORT_SYMBOL_GPL(ip6_local_out);
176