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 static u32 __ipv6_select_ident(struct net *net, u32 hashrnd,
  13                                const struct in6_addr *dst,
  14                                const struct in6_addr *src)
  15 {
  16         u32 hash, id;
  17
  18         hash = __ipv6_addr_jhash(dst, hashrnd);
  19         hash = __ipv6_addr_jhash(src, hash);
  20         hash ^= net_hash_mix(net);
  21
  22         /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
  23          * set the hight order instead thus minimizing possible future
  24          * collisions.
  25          */
  26         id = ip_idents_reserve(hash, 1);
  27         if (unlikely(!id))
  28                 id = 1 << 31;
  29
  30         return id;
  31 }
  32
  33 /* This function exists only for tap drivers that must support broken
  34  * clients requesting UFO without specifying an IPv6 fragment ID.
  35  *
  36  * This is similar to ipv6_select_ident() but we use an independent hash
  37  * seed to limit information leakage.
  38  *
  39  * The network header must be set before calling this.
  40  */
  41 void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
  42 {
  43         static u32 ip6_proxy_idents_hashrnd __read_mostly;
  44         struct in6_addr buf[2];
  45         struct in6_addr *addrs;
  46         u32 id;
  47
  48         addrs = skb_header_pointer(skb,
  49                                    skb_network_offset(skb) +
  50                                    offsetof(struct ipv6hdr, saddr),
  51                                    sizeof(buf), buf);
  52         if (!addrs)
  53                 return;
  54
  55         net_get_random_once(&ip6_proxy_idents_hashrnd,
  56                             sizeof(ip6_proxy_idents_hashrnd));
  57
  58         id = __ipv6_select_ident(net, ip6_proxy_idents_hashrnd,
  59                                  &addrs[1], &addrs[0]);
  60         skb_shinfo(skb)->ip6_frag_id = htonl(id);
  61 }
  62 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  63
  64 __be32 ipv6_select_ident(struct net *net,
  65                          const struct in6_addr *daddr,
  66                          const struct in6_addr *saddr)
  67 {
  68         static u32 ip6_idents_hashrnd __read_mostly;
  69         u32 id;
  70
  71         net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
  72
  73         id = __ipv6_select_ident(net, ip6_idents_hashrnd, daddr, saddr);
  74         return htonl(id);
  75 }
  76 EXPORT_SYMBOL(ipv6_select_ident);
  77
  78 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  79 {
  80         u16 offset = sizeof(struct ipv6hdr);
  81         struct ipv6_opt_hdr *exthdr =
  82                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  83         unsigned int packet_len = skb_tail_pointer(skb) -
  84                 skb_network_header(skb);
  85         int found_rhdr = 0;
  86         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  87
  88         while (offset + 1 <= packet_len) {
  89
  90                 switch (**nexthdr) {
  91
  92                 case NEXTHDR_HOP:
  93                         break;
  94                 case NEXTHDR_ROUTING:
  95                         found_rhdr = 1;
  96                         break;
  97                 case NEXTHDR_DEST:
  98 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  99                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 100                                 break;
 101 #endif
 102                         if (found_rhdr)
 103                                 return offset;
 104                         break;
 105                 default:
 106                         return offset;
 107                 }
 108
 109                 offset += ipv6_optlen(exthdr);
 110                 *nexthdr = &exthdr->nexthdr;
 111                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 112                                                  offset);
 113         }
 114
 115         return offset;
 116 }
 117 EXPORT_SYMBOL(ip6_find_1stfragopt);
 118
 119 #if IS_ENABLED(CONFIG_IPV6)
 120 int ip6_dst_hoplimit(struct dst_entry *dst)
 121 {
 122         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 123         if (hoplimit == 0) {
 124                 struct net_device *dev = dst->dev;
 125                 struct inet6_dev *idev;
 126
 127                 rcu_read_lock();
 128                 idev = __in6_dev_get(dev);
 129                 if (idev)
 130                         hoplimit = idev->cnf.hop_limit;
 131                 else
 132                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 133                 rcu_read_unlock();
 134         }
 135         return hoplimit;
 136 }
 137 EXPORT_SYMBOL(ip6_dst_hoplimit);
 138 #endif
 139
 140 static int __ip6_local_out_sk(struct sock *sk, struct sk_buff *skb)
 141 {
 142         int len;
 143
 144         len = skb->len - sizeof(struct ipv6hdr);
 145         if (len > IPV6_MAXPLEN)
 146                 len = 0;
 147         ipv6_hdr(skb)->payload_len = htons(len);
 148         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 149
 150         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, sk, skb,
 151                        NULL, skb_dst(skb)->dev, dst_output_sk);
 152 }
 153
 154 int __ip6_local_out(struct sk_buff *skb)
 155 {
 156         return __ip6_local_out_sk(skb->sk, skb);
 157 }
 158 EXPORT_SYMBOL_GPL(__ip6_local_out);
 159
 160 int ip6_local_out_sk(struct sock *sk, struct sk_buff *skb)
 161 {
 162         int err;
 163
 164         err = __ip6_local_out_sk(sk, skb);
 165         if (likely(err == 1))
 166                 err = dst_output_sk(sk, skb);
 167
 168         return err;
 169 }
 170 EXPORT_SYMBOL_GPL(ip6_local_out_sk);
 171
 172 int ip6_local_out(struct sk_buff *skb)
 173 {
 174         return ip6_local_out_sk(skb->sk, skb);
 175 }
 176 EXPORT_SYMBOL_GPL(ip6_local_out);