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 u32 __ipv6_select_ident(u32 hashrnd, struct in6_addr *dst, struct in6_addr *src)
  13 {
  14         u32 hash, id;
  15
  16         hash = __ipv6_addr_jhash(dst, hashrnd);
  17         hash = __ipv6_addr_jhash(src, hash);
  18
  19         /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
  20          * set the hight order instead thus minimizing possible future
  21          * collisions.
  22          */
  23         id = ip_idents_reserve(hash, 1);
  24         if (unlikely(!id))
  25                 id = 1 << 31;
  26
  27         return id;
  28 }
  29
  30 /* This function exists only for tap drivers that must support broken
  31  * clients requesting UFO without specifying an IPv6 fragment ID.
  32  *
  33  * This is similar to ipv6_select_ident() but we use an independent hash
  34  * seed to limit information leakage.
  35  *
  36  * The network header must be set before calling this.
  37  */
  38 void ipv6_proxy_select_ident(struct sk_buff *skb)
  39 {
  40         static u32 ip6_proxy_idents_hashrnd __read_mostly;
  41         struct in6_addr buf[2];
  42         struct in6_addr *addrs;
  43         u32 id;
  44
  45         addrs = skb_header_pointer(skb,
  46                                    skb_network_offset(skb) +
  47                                    offsetof(struct ipv6hdr, saddr),
  48                                    sizeof(buf), buf);
  49         if (!addrs)
  50                 return;
  51
  52         net_get_random_once(&ip6_proxy_idents_hashrnd,
  53                             sizeof(ip6_proxy_idents_hashrnd));
  54
  55         id = __ipv6_select_ident(ip6_proxy_idents_hashrnd,
  56                                  &addrs[1], &addrs[0]);
  57         skb_shinfo(skb)->ip6_frag_id = id;
  58 }
  59 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  60
  61 void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
  62 {
  63         static u32 ip6_idents_hashrnd __read_mostly;
  64         u32 id;
  65
  66         net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
  67
  68         id = __ipv6_select_ident(ip6_idents_hashrnd, &rt->rt6i_dst.addr,
  69                                  &rt->rt6i_src.addr);
  70         fhdr->identification = htonl(id);
  71 }
  72 EXPORT_SYMBOL(ipv6_select_ident);
  73
  74 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  75 {
  76         u16 offset = sizeof(struct ipv6hdr);
  77         struct ipv6_opt_hdr *exthdr =
  78                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  79         unsigned int packet_len = skb_tail_pointer(skb) -
  80                 skb_network_header(skb);
  81         int found_rhdr = 0;
  82         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  83
  84         while (offset + 1 <= packet_len) {
  85
  86                 switch (**nexthdr) {
  87
  88                 case NEXTHDR_HOP:
  89                         break;
  90                 case NEXTHDR_ROUTING:
  91                         found_rhdr = 1;
  92                         break;
  93                 case NEXTHDR_DEST:
  94 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  95                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  96                                 break;
  97 #endif
  98                         if (found_rhdr)
  99                                 return offset;
 100                         break;
 101                 default:
 102                         return offset;
 103                 }
 104
 105                 offset += ipv6_optlen(exthdr);
 106                 *nexthdr = &exthdr->nexthdr;
 107                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 108                                                  offset);
 109         }
 110
 111         return offset;
 112 }
 113 EXPORT_SYMBOL(ip6_find_1stfragopt);
 114
 115 #if IS_ENABLED(CONFIG_IPV6)
 116 int ip6_dst_hoplimit(struct dst_entry *dst)
 117 {
 118         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 119         if (hoplimit == 0) {
 120                 struct net_device *dev = dst->dev;
 121                 struct inet6_dev *idev;
 122
 123                 rcu_read_lock();
 124                 idev = __in6_dev_get(dev);
 125                 if (idev)
 126                         hoplimit = idev->cnf.hop_limit;
 127                 else
 128                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 129                 rcu_read_unlock();
 130         }
 131         return hoplimit;
 132 }
 133 EXPORT_SYMBOL(ip6_dst_hoplimit);
 134 #endif
 135
 136 int __ip6_local_out(struct sk_buff *skb)
 137 {
 138         int len;
 139
 140         len = skb->len - sizeof(struct ipv6hdr);
 141         if (len > IPV6_MAXPLEN)
 142                 len = 0;
 143         ipv6_hdr(skb)->payload_len = htons(len);
 144         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 145
 146         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL,
 147                        skb_dst(skb)->dev, dst_output);
 148 }
 149 EXPORT_SYMBOL_GPL(__ip6_local_out);
 150
 151 int ip6_local_out(struct sk_buff *skb)
 152 {
 153         int err;
 154
 155         err = __ip6_local_out(skb);
 156         if (likely(err == 1))
 157                 err = dst_output(skb);
 158
 159         return err;
 160 }
 161 EXPORT_SYMBOL_GPL(ip6_local_out);