net/ipv6/output_core.c

   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 = READ_ONCE(idev->cnf.hop_limit);
 115                 else
 116                         hoplimit = READ_ONCE(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);