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#include <linux/netfilter.h>
12
13static u32 __ipv6_select_ident(struct net *net, u32 hashrnd,
14			       const struct in6_addr *dst,
15			       const struct in6_addr *src)
16{
17	u32 hash, id;
18
19	hash = __ipv6_addr_jhash(dst, hashrnd);
20	hash = __ipv6_addr_jhash(src, hash);
21	hash ^= net_hash_mix(net);
22
23	/* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
24	 * set the hight order instead thus minimizing possible future
25	 * collisions.
26	 */
27	id = ip_idents_reserve(hash, 1);
28	if (unlikely(!id))
29		id = 1 << 31;
30
31	return id;
32}
33
34/* This function exists only for tap drivers that must support broken
35 * clients requesting UFO without specifying an IPv6 fragment ID.
36 *
37 * This is similar to ipv6_select_ident() but we use an independent hash
38 * seed to limit information leakage.
39 *
40 * The network header must be set before calling this.
41 */
42void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
43{
44	static u32 ip6_proxy_idents_hashrnd __read_mostly;
45	struct in6_addr buf[2];
46	struct in6_addr *addrs;
47	u32 id;
48
49	addrs = skb_header_pointer(skb,
50				   skb_network_offset(skb) +
51				   offsetof(struct ipv6hdr, saddr),
52				   sizeof(buf), buf);
53	if (!addrs)
54		return;
55
56	net_get_random_once(&ip6_proxy_idents_hashrnd,
57			    sizeof(ip6_proxy_idents_hashrnd));
58
59	id = __ipv6_select_ident(net, ip6_proxy_idents_hashrnd,
60				 &addrs[1], &addrs[0]);
61	skb_shinfo(skb)->ip6_frag_id = htonl(id);
62}
63EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
64
65__be32 ipv6_select_ident(struct net *net,
66			 const struct in6_addr *daddr,
67			 const struct in6_addr *saddr)
68{
69	static u32 ip6_idents_hashrnd __read_mostly;
70	u32 id;
71
72	net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
73
74	id = __ipv6_select_ident(net, ip6_idents_hashrnd, daddr, saddr);
75	return htonl(id);
76}
77EXPORT_SYMBOL(ipv6_select_ident);
78
79int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
80{
81	u16 offset = sizeof(struct ipv6hdr);
82	struct ipv6_opt_hdr *exthdr =
83				(struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
84	unsigned int packet_len = skb_tail_pointer(skb) -
85		skb_network_header(skb);
86	int found_rhdr = 0;
87	*nexthdr = &ipv6_hdr(skb)->nexthdr;
88
89	while (offset + 1 <= packet_len) {
90
91		switch (**nexthdr) {
92
93		case NEXTHDR_HOP:
94			break;
95		case NEXTHDR_ROUTING:
96			found_rhdr = 1;
97			break;
98		case NEXTHDR_DEST:
99#if IS_ENABLED(CONFIG_IPV6_MIP6)
100			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
101				break;
102#endif
103			if (found_rhdr)
104				return offset;
105			break;
106		default:
107			return offset;
108		}
109
110		offset += ipv6_optlen(exthdr);
111		*nexthdr = &exthdr->nexthdr;
112		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
113						 offset);
114	}
115
116	return offset;
117}
118EXPORT_SYMBOL(ip6_find_1stfragopt);
119
120#if IS_ENABLED(CONFIG_IPV6)
121int ip6_dst_hoplimit(struct dst_entry *dst)
122{
123	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
124	if (hoplimit == 0) {
125		struct net_device *dev = dst->dev;
126		struct inet6_dev *idev;
127
128		rcu_read_lock();
129		idev = __in6_dev_get(dev);
130		if (idev)
131			hoplimit = idev->cnf.hop_limit;
132		else
133			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
134		rcu_read_unlock();
135	}
136	return hoplimit;
137}
138EXPORT_SYMBOL(ip6_dst_hoplimit);
139#endif
140
141int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
142{
143	int len;
144
145	len = skb->len - sizeof(struct ipv6hdr);
146	if (len > IPV6_MAXPLEN)
147		len = 0;
148	ipv6_hdr(skb)->payload_len = htons(len);
149	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
150
151	return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
152		       net, sk, skb, NULL, skb_dst(skb)->dev,
153		       dst_output);
154}
155EXPORT_SYMBOL_GPL(__ip6_local_out);
156
157int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
158{
159	int err;
160
161	err = __ip6_local_out(net, sk, skb);
162	if (likely(err == 1))
163		err = dst_output(net, sk, skb);
164
165	return err;
166}
167EXPORT_SYMBOL_GPL(ip6_local_out);
168