net/ipv6/output_core.c

   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,
  14                                const struct in6_addr *dst,
  15                                const struct in6_addr *src)
  16 {
  17         u32 id;
  18
  19         do {
  20                 id = prandom_u32();
  21         } while (!id);
  22
  23         return id;
  24 }
  25
  26 /* This function exists only for tap drivers that must support broken
  27  * clients requesting UFO without specifying an IPv6 fragment ID.
  28  *
  29  * This is similar to ipv6_select_ident() but we use an independent hash
  30  * seed to limit information leakage.
  31  *
  32  * The network header must be set before calling this.
  33  */
  34 void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
  35 {
  36         struct in6_addr buf[2];
  37         struct in6_addr *addrs;
  38         u32 id;
  39
  40         addrs = skb_header_pointer(skb,
  41                                    skb_network_offset(skb) +
  42                                    offsetof(struct ipv6hdr, saddr),
  43                                    sizeof(buf), buf);
  44         if (!addrs)
  45                 return;
  46
  47         id = __ipv6_select_ident(net, &addrs[1], &addrs[0]);
  48         skb_shinfo(skb)->ip6_frag_id = htonl(id);
  49 }
  50 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  51
  52 __be32 ipv6_select_ident(struct net *net,
  53                          const struct in6_addr *daddr,
  54                          const struct in6_addr *saddr)
  55 {
  56         u32 id;
  57
  58         id = __ipv6_select_ident(net, daddr, saddr);
  59         return htonl(id);
  60 }
  61 EXPORT_SYMBOL(ipv6_select_ident);
  62
  63 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  64 {
  65         unsigned int offset = sizeof(struct ipv6hdr);
  66         unsigned int packet_len = skb_tail_pointer(skb) -
  67                 skb_network_header(skb);
  68         int found_rhdr = 0;
  69         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  70
  71         while (offset <= packet_len) {
  72                 struct ipv6_opt_hdr *exthdr;
  73
  74                 switch (**nexthdr) {
  75
  76                 case NEXTHDR_HOP:
  77                         break;
  78                 case NEXTHDR_ROUTING:
  79                         found_rhdr = 1;
  80                         break;
  81                 case NEXTHDR_DEST:
  82 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  83                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  84                                 break;
  85 #endif
  86                         if (found_rhdr)
  87                                 return offset;
  88                         break;
  89                 default:
  90                         return offset;
  91                 }
  92
  93                 if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
  94                         return -EINVAL;
  95
  96                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
  97                                                  offset);
  98                 offset += ipv6_optlen(exthdr);
  99                 if (offset > IPV6_MAXPLEN)
 100                         return -EINVAL;
 101                 *nexthdr = &exthdr->nexthdr;
 102         }
 103
 104         return -EINVAL;
 105 }
 106 EXPORT_SYMBOL(ip6_find_1stfragopt);
 107
 108 #if IS_ENABLED(CONFIG_IPV6)
 109 int ip6_dst_hoplimit(struct dst_entry *dst)
 110 {
 111         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 112         if (hoplimit == 0) {
 113                 struct net_device *dev = dst->dev;
 114                 struct inet6_dev *idev;
 115
 116                 rcu_read_lock();
 117                 idev = __in6_dev_get(dev);
 118                 if (idev)
 119                         hoplimit = idev->cnf.hop_limit;
 120                 else
 121                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 122                 rcu_read_unlock();
 123         }
 124         return hoplimit;
 125 }
 126 EXPORT_SYMBOL(ip6_dst_hoplimit);
 127 #endif
 128
 129 int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 130 {
 131         int len;
 132
 133         len = skb->len - sizeof(struct ipv6hdr);
 134         if (len > IPV6_MAXPLEN)
 135                 len = 0;
 136         ipv6_hdr(skb)->payload_len = htons(len);
 137         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 138
 139         /* if egress device is enslaved to an L3 master device pass the
 140          * skb to its handler for processing
 141          */
 142         skb = l3mdev_ip6_out(sk, skb);
 143         if (unlikely(!skb))
 144                 return 0;
 145
 146         skb->protocol = htons(ETH_P_IPV6);
 147
 148         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 149                        net, sk, skb, NULL, skb_dst(skb)->dev,
 150                        dst_output);
 151 }
 152 EXPORT_SYMBOL_GPL(__ip6_local_out);
 153
 154 int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 155 {
 156         int err;
 157
 158         err = __ip6_local_out(net, sk, skb);
 159         if (likely(err == 1))
 160                 err = dst_output(net, sk, skb);
 161
 162         return err;
 163 }
 164 EXPORT_SYMBOL_GPL(ip6_local_out);