1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * IPv6 library code, needed by static components when full IPv6 support is
  4 * not configured or static.  These functions are needed by GSO/GRO implementation.
  5 */
  6#include <linux/export.h>
  7#include <net/ip.h>
  8#include <net/ipv6.h>
  9#include <net/ip6_fib.h>
 10#include <net/addrconf.h>
 11#include <net/secure_seq.h>
 12#include <linux/netfilter.h>
 13
 14static u32 __ipv6_select_ident(struct net *net,
 15			       const struct in6_addr *dst,
 16			       const struct in6_addr *src)
 17{
 18	return get_random_u32_above(0);
 19}
 20
 21/* This function exists only for tap drivers that must support broken
 22 * clients requesting UFO without specifying an IPv6 fragment ID.
 23 *
 24 * This is similar to ipv6_select_ident() but we use an independent hash
 25 * seed to limit information leakage.
 26 *
 27 * The network header must be set before calling this.
 28 */
 29__be32 ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
 30{
 31	struct in6_addr buf[2];
 32	struct in6_addr *addrs;
 33	u32 id;
 34
 35	addrs = skb_header_pointer(skb,
 36				   skb_network_offset(skb) +
 37				   offsetof(struct ipv6hdr, saddr),
 38				   sizeof(buf), buf);
 39	if (!addrs)
 40		return 0;
 41
 42	id = __ipv6_select_ident(net, &addrs[1], &addrs[0]);
 43	return htonl(id);
 44}
 45EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
 46
 47__be32 ipv6_select_ident(struct net *net,
 48			 const struct in6_addr *daddr,
 49			 const struct in6_addr *saddr)
 50{
 51	u32 id;
 52
 53	id = __ipv6_select_ident(net, daddr, saddr);
 54	return htonl(id);
 55}
 56EXPORT_SYMBOL(ipv6_select_ident);
 57
 58int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 59{
 60	unsigned int offset = sizeof(struct ipv6hdr);
 61	unsigned int packet_len = skb_tail_pointer(skb) -
 62		skb_network_header(skb);
 63	int found_rhdr = 0;
 64	*nexthdr = &ipv6_hdr(skb)->nexthdr;
 65
 66	while (offset <= packet_len) {
 67		struct ipv6_opt_hdr *exthdr;
 68
 69		switch (**nexthdr) {
 70
 71		case NEXTHDR_HOP:
 72			break;
 73		case NEXTHDR_ROUTING:
 74			found_rhdr = 1;
 75			break;
 76		case NEXTHDR_DEST:
 77#if IS_ENABLED(CONFIG_IPV6_MIP6)
 78			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 79				break;
 80#endif
 81			if (found_rhdr)
 82				return offset;
 83			break;
 84		default:
 85			return offset;
 86		}
 87
 88		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
 89			return -EINVAL;
 90
 91		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 92						 offset);
 93		offset += ipv6_optlen(exthdr);
 94		if (offset > IPV6_MAXPLEN)
 95			return -EINVAL;
 96		*nexthdr = &exthdr->nexthdr;
 97	}
 98
 99	return -EINVAL;
100}
101EXPORT_SYMBOL(ip6_find_1stfragopt);
102
103#if IS_ENABLED(CONFIG_IPV6)
104int ip6_dst_hoplimit(struct dst_entry *dst)
105{
106	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
107	if (hoplimit == 0) {
108		struct net_device *dev = dst->dev;
109		struct inet6_dev *idev;
110
111		rcu_read_lock();
112		idev = __in6_dev_get(dev);
113		if (idev)
114			hoplimit = READ_ONCE(idev->cnf.hop_limit);
115		else
116			hoplimit = READ_ONCE(dev_net(dev)->ipv6.devconf_all->hop_limit);
117		rcu_read_unlock();
118	}
119	return hoplimit;
120}
121EXPORT_SYMBOL(ip6_dst_hoplimit);
122#endif
123
124int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
125{
126	int len;
127
128	len = skb->len - sizeof(struct ipv6hdr);
129	if (len > IPV6_MAXPLEN)
130		len = 0;
131	ipv6_hdr(skb)->payload_len = htons(len);
132	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
133
134	/* if egress device is enslaved to an L3 master device pass the
135	 * skb to its handler for processing
136	 */
137	skb = l3mdev_ip6_out(sk, skb);
138	if (unlikely(!skb))
139		return 0;
140
141	skb->protocol = htons(ETH_P_IPV6);
142
143	return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
144		       net, sk, skb, NULL, skb_dst(skb)->dev,
145		       dst_output);
146}
147EXPORT_SYMBOL_GPL(__ip6_local_out);
148
149int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
150{
151	int err;
152
153	err = __ip6_local_out(net, sk, skb);
154	if (likely(err == 1))
155		err = dst_output(net, sk, skb);
156
157	return err;
158}
159EXPORT_SYMBOL_GPL(ip6_local_out);