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	const struct {
 19		struct in6_addr dst;
 20		struct in6_addr src;
 21	} __aligned(SIPHASH_ALIGNMENT) combined = {
 22		.dst = *dst,
 23		.src = *src,
 24	};
 25	u32 hash, id;
 26
 27	/* Note the following code is not safe, but this is okay. */
 28	if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key)))
 29		get_random_bytes(&net->ipv4.ip_id_key,
 30				 sizeof(net->ipv4.ip_id_key));
 31
 32	hash = siphash(&combined, sizeof(combined), &net->ipv4.ip_id_key);
 33
 34	/* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
 35	 * set the hight order instead thus minimizing possible future
 36	 * collisions.
 37	 */
 38	id = ip_idents_reserve(hash, 1);
 39	if (unlikely(!id))
 40		id = 1 << 31;
 41
 42	return id;
 43}
 44
 45/* This function exists only for tap drivers that must support broken
 46 * clients requesting UFO without specifying an IPv6 fragment ID.
 47 *
 48 * This is similar to ipv6_select_ident() but we use an independent hash
 49 * seed to limit information leakage.
 50 *
 51 * The network header must be set before calling this.
 52 */
 53__be32 ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
 54{
 55	struct in6_addr buf[2];
 56	struct in6_addr *addrs;
 57	u32 id;
 58
 59	addrs = skb_header_pointer(skb,
 60				   skb_network_offset(skb) +
 61				   offsetof(struct ipv6hdr, saddr),
 62				   sizeof(buf), buf);
 63	if (!addrs)
 64		return 0;
 65
 66	id = __ipv6_select_ident(net, &addrs[1], &addrs[0]);
 67	return htonl(id);
 68}
 69EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
 70
 71__be32 ipv6_select_ident(struct net *net,
 72			 const struct in6_addr *daddr,
 73			 const struct in6_addr *saddr)
 74{
 75	u32 id;
 76
 77	id = __ipv6_select_ident(net, daddr, saddr);
 78	return htonl(id);
 79}
 80EXPORT_SYMBOL(ipv6_select_ident);
 81
 82int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 83{
 84	unsigned int offset = sizeof(struct ipv6hdr);
 85	unsigned int packet_len = skb_tail_pointer(skb) -
 86		skb_network_header(skb);
 87	int found_rhdr = 0;
 88	*nexthdr = &ipv6_hdr(skb)->nexthdr;
 89
 90	while (offset <= packet_len) {
 91		struct ipv6_opt_hdr *exthdr;
 92
 93		switch (**nexthdr) {
 94
 95		case NEXTHDR_HOP:
 96			break;
 97		case NEXTHDR_ROUTING:
 98			found_rhdr = 1;
 99			break;
100		case NEXTHDR_DEST:
101#if IS_ENABLED(CONFIG_IPV6_MIP6)
102			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
103				break;
104#endif
105			if (found_rhdr)
106				return offset;
107			break;
108		default:
109			return offset;
110		}
111
112		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
113			return -EINVAL;
114
115		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
116						 offset);
117		offset += ipv6_optlen(exthdr);
118		if (offset > IPV6_MAXPLEN)
119			return -EINVAL;
120		*nexthdr = &exthdr->nexthdr;
121	}
122
123	return -EINVAL;
124}
125EXPORT_SYMBOL(ip6_find_1stfragopt);
126
127#if IS_ENABLED(CONFIG_IPV6)
128int ip6_dst_hoplimit(struct dst_entry *dst)
129{
130	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
131	if (hoplimit == 0) {
132		struct net_device *dev = dst->dev;
133		struct inet6_dev *idev;
134
135		rcu_read_lock();
136		idev = __in6_dev_get(dev);
137		if (idev)
138			hoplimit = idev->cnf.hop_limit;
139		else
140			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
141		rcu_read_unlock();
142	}
143	return hoplimit;
144}
145EXPORT_SYMBOL(ip6_dst_hoplimit);
146#endif
147
148int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
149{
150	int len;
151
152	len = skb->len - sizeof(struct ipv6hdr);
153	if (len > IPV6_MAXPLEN)
154		len = 0;
155	ipv6_hdr(skb)->payload_len = htons(len);
156	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
157
158	/* if egress device is enslaved to an L3 master device pass the
159	 * skb to its handler for processing
160	 */
161	skb = l3mdev_ip6_out(sk, skb);
162	if (unlikely(!skb))
163		return 0;
164
165	skb->protocol = htons(ETH_P_IPV6);
166
167	return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
168		       net, sk, skb, NULL, skb_dst(skb)->dev,
169		       dst_output);
170}
171EXPORT_SYMBOL_GPL(__ip6_local_out);
172
173int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
174{
175	int err;
176
177	err = __ip6_local_out(net, sk, skb);
178	if (likely(err == 1))
179		err = dst_output(net, sk, skb);
180
181	return err;
182}
183EXPORT_SYMBOL_GPL(ip6_local_out);