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	u32 id;
 19
 20	do {
 21		id = prandom_u32();
 22	} while (!id);
 23
 24	return id;
 25}
 26
 27/* This function exists only for tap drivers that must support broken
 28 * clients requesting UFO without specifying an IPv6 fragment ID.
 29 *
 30 * This is similar to ipv6_select_ident() but we use an independent hash
 31 * seed to limit information leakage.
 32 *
 33 * The network header must be set before calling this.
 34 */
 35__be32 ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
 36{
 37	struct in6_addr buf[2];
 38	struct in6_addr *addrs;
 39	u32 id;
 40
 41	addrs = skb_header_pointer(skb,
 42				   skb_network_offset(skb) +
 43				   offsetof(struct ipv6hdr, saddr),
 44				   sizeof(buf), buf);
 45	if (!addrs)
 46		return 0;
 47
 48	id = __ipv6_select_ident(net, &addrs[1], &addrs[0]);
 49	return htonl(id);
 50}
 51EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
 52
 53__be32 ipv6_select_ident(struct net *net,
 54			 const struct in6_addr *daddr,
 55			 const struct in6_addr *saddr)
 56{
 57	u32 id;
 58
 59	id = __ipv6_select_ident(net, daddr, saddr);
 60	return htonl(id);
 61}
 62EXPORT_SYMBOL(ipv6_select_ident);
 63
 64int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 65{
 66	unsigned int offset = sizeof(struct ipv6hdr);
 67	unsigned int packet_len = skb_tail_pointer(skb) -
 68		skb_network_header(skb);
 69	int found_rhdr = 0;
 70	*nexthdr = &ipv6_hdr(skb)->nexthdr;
 71
 72	while (offset <= packet_len) {
 73		struct ipv6_opt_hdr *exthdr;
 74
 75		switch (**nexthdr) {
 76
 77		case NEXTHDR_HOP:
 78			break;
 79		case NEXTHDR_ROUTING:
 80			found_rhdr = 1;
 81			break;
 82		case NEXTHDR_DEST:
 83#if IS_ENABLED(CONFIG_IPV6_MIP6)
 84			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 85				break;
 86#endif
 87			if (found_rhdr)
 88				return offset;
 89			break;
 90		default:
 91			return offset;
 92		}
 93
 94		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
 95			return -EINVAL;
 96
 97		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 98						 offset);
 99		offset += ipv6_optlen(exthdr);
100		if (offset > IPV6_MAXPLEN)
101			return -EINVAL;
102		*nexthdr = &exthdr->nexthdr;
103	}
104
105	return -EINVAL;
106}
107EXPORT_SYMBOL(ip6_find_1stfragopt);
108
109#if IS_ENABLED(CONFIG_IPV6)
110int ip6_dst_hoplimit(struct dst_entry *dst)
111{
112	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
113	if (hoplimit == 0) {
114		struct net_device *dev = dst->dev;
115		struct inet6_dev *idev;
116
117		rcu_read_lock();
118		idev = __in6_dev_get(dev);
119		if (idev)
120			hoplimit = idev->cnf.hop_limit;
121		else
122			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
123		rcu_read_unlock();
124	}
125	return hoplimit;
126}
127EXPORT_SYMBOL(ip6_dst_hoplimit);
128#endif
129
130int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
131{
132	int len;
133
134	len = skb->len - sizeof(struct ipv6hdr);
135	if (len > IPV6_MAXPLEN)
136		len = 0;
137	ipv6_hdr(skb)->payload_len = htons(len);
138	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
139
140	/* if egress device is enslaved to an L3 master device pass the
141	 * skb to its handler for processing
142	 */
143	skb = l3mdev_ip6_out(sk, skb);
144	if (unlikely(!skb))
145		return 0;
146
147	skb->protocol = htons(ETH_P_IPV6);
148
149	return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
150		       net, sk, skb, NULL, skb_dst(skb)->dev,
151		       dst_output);
152}
153EXPORT_SYMBOL_GPL(__ip6_local_out);
154
155int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
156{
157	int err;
158
159	err = __ip6_local_out(net, sk, skb);
160	if (likely(err == 1))
161		err = dst_output(net, sk, skb);
162
163	return err;
164}
165EXPORT_SYMBOL_GPL(ip6_local_out);