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
  11 /* This function exists only for tap drivers that must support broken
  12  * clients requesting UFO without specifying an IPv6 fragment ID.
  13  *
  14  * This is similar to ipv6_select_ident() but we use an independent hash
  15  * seed to limit information leakage.
  16  *
  17  * The network header must be set before calling this.
  18  */
  19 void ipv6_proxy_select_ident(struct sk_buff *skb)
  20 {
  21         static u32 ip6_proxy_idents_hashrnd __read_mostly;
  22         struct in6_addr buf[2];
  23         struct in6_addr *addrs;
  24         u32 hash, id;
  25
  26         addrs = skb_header_pointer(skb,
  27                                    skb_network_offset(skb) +
  28                                    offsetof(struct ipv6hdr, saddr),
  29                                    sizeof(buf), buf);
  30         if (!addrs)
  31                 return;
  32
  33         net_get_random_once(&ip6_proxy_idents_hashrnd,
  34                             sizeof(ip6_proxy_idents_hashrnd));
  35
  36         hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
  37         hash = __ipv6_addr_jhash(&addrs[0], hash);
  38
  39         id = ip_idents_reserve(hash, 1);
  40         skb_shinfo(skb)->ip6_frag_id = htonl(id);
  41 }
  42 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  43
  44 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  45 {
  46         u16 offset = sizeof(struct ipv6hdr);
  47         struct ipv6_opt_hdr *exthdr =
  48                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  49         unsigned int packet_len = skb_tail_pointer(skb) -
  50                 skb_network_header(skb);
  51         int found_rhdr = 0;
  52         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  53
  54         while (offset + 1 <= packet_len) {
  55
  56                 switch (**nexthdr) {
  57
  58                 case NEXTHDR_HOP:
  59                         break;
  60                 case NEXTHDR_ROUTING:
  61                         found_rhdr = 1;
  62                         break;
  63                 case NEXTHDR_DEST:
  64 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  65                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  66                                 break;
  67 #endif
  68                         if (found_rhdr)
  69                                 return offset;
  70                         break;
  71                 default :
  72                         return offset;
  73                 }
  74
  75                 offset += ipv6_optlen(exthdr);
  76                 *nexthdr = &exthdr->nexthdr;
  77                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
  78                                                  offset);
  79         }
  80
  81         return offset;
  82 }
  83 EXPORT_SYMBOL(ip6_find_1stfragopt);
  84
  85 #if IS_ENABLED(CONFIG_IPV6)
  86 int ip6_dst_hoplimit(struct dst_entry *dst)
  87 {
  88         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
  89         if (hoplimit == 0) {
  90                 struct net_device *dev = dst->dev;
  91                 struct inet6_dev *idev;
  92
  93                 rcu_read_lock();
  94                 idev = __in6_dev_get(dev);
  95                 if (idev)
  96                         hoplimit = idev->cnf.hop_limit;
  97                 else
  98                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
  99                 rcu_read_unlock();
 100         }
 101         return hoplimit;
 102 }
 103 EXPORT_SYMBOL(ip6_dst_hoplimit);
 104 #endif
 105
 106 int __ip6_local_out(struct sk_buff *skb)
 107 {
 108         int len;
 109
 110         len = skb->len - sizeof(struct ipv6hdr);
 111         if (len > IPV6_MAXPLEN)
 112                 len = 0;
 113         ipv6_hdr(skb)->payload_len = htons(len);
 114
 115         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL,
 116                        skb_dst(skb)->dev, dst_output);
 117 }
 118 EXPORT_SYMBOL_GPL(__ip6_local_out);
 119
 120 int ip6_local_out(struct sk_buff *skb)
 121 {
 122         int err;
 123
 124         err = __ip6_local_out(skb);
 125         if (likely(err == 1))
 126                 err = dst_output(skb);
 127
 128         return err;
 129 }
 130 EXPORT_SYMBOL_GPL(ip6_local_out);