xref: /linux/net/ipv6/output_core.c (revision 0526b56cbc3c489642bd6a5fe4b718dea7ef0ee8)
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 
14 static 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 }
45 EXPORT_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 }
56 EXPORT_SYMBOL(ipv6_select_ident);
57 
58 int 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 }
101 EXPORT_SYMBOL(ip6_find_1stfragopt);
102 
103 #if IS_ENABLED(CONFIG_IPV6)
104 int 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 = idev->cnf.hop_limit;
115 		else
116 			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
117 		rcu_read_unlock();
118 	}
119 	return hoplimit;
120 }
121 EXPORT_SYMBOL(ip6_dst_hoplimit);
122 #endif
123 
124 int __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 }
147 EXPORT_SYMBOL_GPL(__ip6_local_out);
148 
149 int 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 }
159 EXPORT_SYMBOL_GPL(ip6_local_out);
160