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(floor: 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 offset: skb_network_offset(skb) +
37 offsetof(struct ipv6hdr, saddr),
38 len: sizeof(buf), buffer: buf);
39 if (!addrs)
40 return 0;
41
42 id = __ipv6_select_ident(net, dst: &addrs[1], src: &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, dst: daddr, src: 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
108 rcu_read_lock();
109 if (hoplimit == 0) {
110 struct net_device *dev = dst_dev_rcu(dst);
111 struct inet6_dev *idev;
112
113 idev = __in6_dev_get(dev);
114 if (idev)
115 hoplimit = READ_ONCE(idev->cnf.hop_limit);
116 else
117 hoplimit = READ_ONCE(dev_net(dev)->ipv6.devconf_all->hop_limit);
118 }
119 rcu_read_unlock();
120
121 return hoplimit;
122}
123EXPORT_SYMBOL(ip6_dst_hoplimit);
124#endif
125
126int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
127{
128 int len;
129
130 len = skb->len - sizeof(struct ipv6hdr);
131 if (len > IPV6_MAXPLEN)
132 len = 0;
133 ipv6_hdr(skb)->payload_len = htons(len);
134 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
135
136 /* if egress device is enslaved to an L3 master device pass the
137 * skb to its handler for processing
138 */
139 skb = l3mdev_ip6_out(sk, skb);
140 if (unlikely(!skb))
141 return 0;
142
143 skb->protocol = htons(ETH_P_IPV6);
144
145 return nf_hook(pf: NFPROTO_IPV6, hook: NF_INET_LOCAL_OUT,
146 net, sk, skb, NULL, outdev: skb_dst_dev(skb),
147 okfn: dst_output);
148}
149EXPORT_SYMBOL_GPL(__ip6_local_out);
150
151int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
152{
153 int err;
154
155 err = __ip6_local_out(net, sk, skb);
156 if (likely(err == 1))
157 err = dst_output(net, sk, skb);
158
159 return err;
160}
161EXPORT_SYMBOL_GPL(ip6_local_out);
162

source code of linux/net/ipv6/output_core.c