xref: /linux/net/ipv6/output_core.c (revision 507e190946297c34a27d9366b0661d5e506fdd03)
1 /*
2  * IPv6 library code, needed by static components when full IPv6 support is
3  * not configured or static.  These functions are needed by GSO/GRO implementation.
4  */
5 #include <linux/export.h>
6 #include <net/ip.h>
7 #include <net/ipv6.h>
8 #include <net/ip6_fib.h>
9 #include <net/addrconf.h>
10 #include <net/secure_seq.h>
11 #include <linux/netfilter.h>
12 
13 static u32 __ipv6_select_ident(struct net *net, u32 hashrnd,
14 			       const struct in6_addr *dst,
15 			       const struct in6_addr *src)
16 {
17 	u32 hash, id;
18 
19 	hash = __ipv6_addr_jhash(dst, hashrnd);
20 	hash = __ipv6_addr_jhash(src, hash);
21 	hash ^= net_hash_mix(net);
22 
23 	/* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
24 	 * set the hight order instead thus minimizing possible future
25 	 * collisions.
26 	 */
27 	id = ip_idents_reserve(hash, 1);
28 	if (unlikely(!id))
29 		id = 1 << 31;
30 
31 	return id;
32 }
33 
34 /* This function exists only for tap drivers that must support broken
35  * clients requesting UFO without specifying an IPv6 fragment ID.
36  *
37  * This is similar to ipv6_select_ident() but we use an independent hash
38  * seed to limit information leakage.
39  *
40  * The network header must be set before calling this.
41  */
42 void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
43 {
44 	static u32 ip6_proxy_idents_hashrnd __read_mostly;
45 	struct in6_addr buf[2];
46 	struct in6_addr *addrs;
47 	u32 id;
48 
49 	addrs = skb_header_pointer(skb,
50 				   skb_network_offset(skb) +
51 				   offsetof(struct ipv6hdr, saddr),
52 				   sizeof(buf), buf);
53 	if (!addrs)
54 		return;
55 
56 	net_get_random_once(&ip6_proxy_idents_hashrnd,
57 			    sizeof(ip6_proxy_idents_hashrnd));
58 
59 	id = __ipv6_select_ident(net, ip6_proxy_idents_hashrnd,
60 				 &addrs[1], &addrs[0]);
61 	skb_shinfo(skb)->ip6_frag_id = htonl(id);
62 }
63 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
64 
65 __be32 ipv6_select_ident(struct net *net,
66 			 const struct in6_addr *daddr,
67 			 const struct in6_addr *saddr)
68 {
69 	static u32 ip6_idents_hashrnd __read_mostly;
70 	u32 id;
71 
72 	net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
73 
74 	id = __ipv6_select_ident(net, ip6_idents_hashrnd, daddr, saddr);
75 	return htonl(id);
76 }
77 EXPORT_SYMBOL(ipv6_select_ident);
78 
79 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
80 {
81 	unsigned int offset = sizeof(struct ipv6hdr);
82 	unsigned int packet_len = skb_tail_pointer(skb) -
83 		skb_network_header(skb);
84 	int found_rhdr = 0;
85 	*nexthdr = &ipv6_hdr(skb)->nexthdr;
86 
87 	while (offset <= packet_len) {
88 		struct ipv6_opt_hdr *exthdr;
89 		unsigned int len;
90 
91 		switch (**nexthdr) {
92 
93 		case NEXTHDR_HOP:
94 			break;
95 		case NEXTHDR_ROUTING:
96 			found_rhdr = 1;
97 			break;
98 		case NEXTHDR_DEST:
99 #if IS_ENABLED(CONFIG_IPV6_MIP6)
100 			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
101 				break;
102 #endif
103 			if (found_rhdr)
104 				return offset;
105 			break;
106 		default:
107 			return offset;
108 		}
109 
110 		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
111 			return -EINVAL;
112 
113 		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
114 						 offset);
115 		len = ipv6_optlen(exthdr);
116 		if (len + offset >= IPV6_MAXPLEN)
117 			return -EINVAL;
118 		offset += len;
119 		*nexthdr = &exthdr->nexthdr;
120 	}
121 
122 	return -EINVAL;
123 }
124 EXPORT_SYMBOL(ip6_find_1stfragopt);
125 
126 #if IS_ENABLED(CONFIG_IPV6)
127 int ip6_dst_hoplimit(struct dst_entry *dst)
128 {
129 	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
130 	if (hoplimit == 0) {
131 		struct net_device *dev = dst->dev;
132 		struct inet6_dev *idev;
133 
134 		rcu_read_lock();
135 		idev = __in6_dev_get(dev);
136 		if (idev)
137 			hoplimit = idev->cnf.hop_limit;
138 		else
139 			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
140 		rcu_read_unlock();
141 	}
142 	return hoplimit;
143 }
144 EXPORT_SYMBOL(ip6_dst_hoplimit);
145 #endif
146 
147 int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
148 {
149 	int len;
150 
151 	len = skb->len - sizeof(struct ipv6hdr);
152 	if (len > IPV6_MAXPLEN)
153 		len = 0;
154 	ipv6_hdr(skb)->payload_len = htons(len);
155 	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
156 
157 	/* if egress device is enslaved to an L3 master device pass the
158 	 * skb to its handler for processing
159 	 */
160 	skb = l3mdev_ip6_out(sk, skb);
161 	if (unlikely(!skb))
162 		return 0;
163 
164 	skb->protocol = htons(ETH_P_IPV6);
165 
166 	return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
167 		       net, sk, skb, NULL, skb_dst(skb)->dev,
168 		       dst_output);
169 }
170 EXPORT_SYMBOL_GPL(__ip6_local_out);
171 
172 int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
173 {
174 	int err;
175 
176 	err = __ip6_local_out(net, sk, skb);
177 	if (likely(err == 1))
178 		err = dst_output(net, sk, skb);
179 
180 	return err;
181 }
182 EXPORT_SYMBOL_GPL(ip6_local_out);
183