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
  12 /* This function exists only for tap drivers that must support broken
  13  * clients requesting UFO without specifying an IPv6 fragment ID.
  14  *
  15  * This is similar to ipv6_select_ident() but we use an independent hash
  16  * seed to limit information leakage.
  17  *
  18  * The network header must be set before calling this.
  19  */
  20 void ipv6_proxy_select_ident(struct sk_buff *skb)
  21 {
  22         static u32 ip6_proxy_idents_hashrnd __read_mostly;
  23         struct in6_addr buf[2];
  24         struct in6_addr *addrs;
  25         u32 hash, id;
  26
  27         addrs = skb_header_pointer(skb,
  28                                    skb_network_offset(skb) +
  29                                    offsetof(struct ipv6hdr, saddr),
  30                                    sizeof(buf), buf);
  31         if (!addrs)
  32                 return;
  33
  34         net_get_random_once(&ip6_proxy_idents_hashrnd,
  35                             sizeof(ip6_proxy_idents_hashrnd));
  36
  37         hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
  38         hash = __ipv6_addr_jhash(&addrs[0], hash);
  39
  40         id = ip_idents_reserve(hash, 1);
  41         skb_shinfo(skb)->ip6_frag_id = htonl(id);
  42 }
  43 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  44
  45 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  46 {
  47         u16 offset = sizeof(struct ipv6hdr);
  48         struct ipv6_opt_hdr *exthdr =
  49                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  50         unsigned int packet_len = skb_tail_pointer(skb) -
  51                 skb_network_header(skb);
  52         int found_rhdr = 0;
  53         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  54
  55         while (offset + 1 <= packet_len) {
  56
  57                 switch (**nexthdr) {
  58
  59                 case NEXTHDR_HOP:
  60                         break;
  61                 case NEXTHDR_ROUTING:
  62                         found_rhdr = 1;
  63                         break;
  64                 case NEXTHDR_DEST:
  65 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  66                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  67                                 break;
  68 #endif
  69                         if (found_rhdr)
  70                                 return offset;
  71                         break;
  72                 default:
  73                         return offset;
  74                 }
  75
  76                 offset += ipv6_optlen(exthdr);
  77                 *nexthdr = &exthdr->nexthdr;
  78                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
  79                                                  offset);
  80         }
  81
  82         return offset;
  83 }
  84 EXPORT_SYMBOL(ip6_find_1stfragopt);
  85
  86 #if IS_ENABLED(CONFIG_IPV6)
  87 int ip6_dst_hoplimit(struct dst_entry *dst)
  88 {
  89         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
  90         if (hoplimit == 0) {
  91                 struct net_device *dev = dst->dev;
  92                 struct inet6_dev *idev;
  93
  94                 rcu_read_lock();
  95                 idev = __in6_dev_get(dev);
  96                 if (idev)
  97                         hoplimit = idev->cnf.hop_limit;
  98                 else
  99                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 100                 rcu_read_unlock();
 101         }
 102         return hoplimit;
 103 }
 104 EXPORT_SYMBOL(ip6_dst_hoplimit);
 105 #endif
 106
 107 int __ip6_local_out(struct sk_buff *skb)
 108 {
 109         int len;
 110
 111         len = skb->len - sizeof(struct ipv6hdr);
 112         if (len > IPV6_MAXPLEN)
 113                 len = 0;
 114         ipv6_hdr(skb)->payload_len = htons(len);
 115         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 116
 117         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL,
 118                        skb_dst(skb)->dev, dst_output);
 119 }
 120 EXPORT_SYMBOL_GPL(__ip6_local_out);
 121
 122 int ip6_local_out(struct sk_buff *skb)
 123 {
 124         int err;
 125
 126         err = __ip6_local_out(skb);
 127         if (likely(err == 1))
 128                 err = dst_output(skb);
 129
 130         return err;
 131 }
 132 EXPORT_SYMBOL_GPL(ip6_local_out);