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 
__ipv6_select_ident(struct net * net,const struct in6_addr * dst,const struct in6_addr * src)14 static 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  */
ipv6_proxy_select_ident(struct net * net,struct sk_buff * skb)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 }
51 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
52 
ipv6_select_ident(struct net * net,const struct in6_addr * daddr,const struct in6_addr * saddr)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 }
62 EXPORT_SYMBOL(ipv6_select_ident);
63 
ip6_find_1stfragopt(struct sk_buff * skb,u8 ** nexthdr)64 int 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 }
107 EXPORT_SYMBOL(ip6_find_1stfragopt);
108 
109 #if IS_ENABLED(CONFIG_IPV6)
ip6_dst_hoplimit(struct dst_entry * dst)110 int 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 }
127 EXPORT_SYMBOL(ip6_dst_hoplimit);
128 #endif
129 
__ip6_local_out(struct net * net,struct sock * sk,struct sk_buff * skb)130 int __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 }
153 EXPORT_SYMBOL_GPL(__ip6_local_out);
154 
ip6_local_out(struct net * net,struct sock * sk,struct sk_buff * skb)155 int 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 }
165 EXPORT_SYMBOL_GPL(ip6_local_out);
166