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, u32 hashrnd,
  14                                const struct in6_addr *dst,
  15                                const struct in6_addr *src)
  16 {
  17         u32 hash, id;
  18
  19         hash = __ipv6_addr_jhash(dst, hashrnd);
  20         hash = __ipv6_addr_jhash(src, hash);
  21         hash ^= net_hash_mix(net);
  22
  23         /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
  24          * set the hight order instead thus minimizing possible future
  25          * collisions.
  26          */
  27         id = ip_idents_reserve(hash, 1);
  28         if (unlikely(!id))
  29                 id = 1 << 31;
  30
  31         return id;
  32 }
  33
  34 __be32 ipv6_select_ident(struct net *net,
  35                          const struct in6_addr *daddr,
  36                          const struct in6_addr *saddr)
  37 {
  38         static u32 ip6_idents_hashrnd __read_mostly;
  39         u32 id;
  40
  41         net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
  42
  43         id = __ipv6_select_ident(net, ip6_idents_hashrnd, daddr, saddr);
  44         return htonl(id);
  45 }
  46 EXPORT_SYMBOL(ipv6_select_ident);
  47
  48 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  49 {
  50         unsigned int offset = sizeof(struct ipv6hdr);
  51         unsigned int packet_len = skb_tail_pointer(skb) -
  52                 skb_network_header(skb);
  53         int found_rhdr = 0;
  54         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  55
  56         while (offset <= packet_len) {
  57                 struct ipv6_opt_hdr *exthdr;
  58
  59                 switch (**nexthdr) {
  60
  61                 case NEXTHDR_HOP:
  62                         break;
  63                 case NEXTHDR_ROUTING:
  64                         found_rhdr = 1;
  65                         break;
  66                 case NEXTHDR_DEST:
  67 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  68                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  69                                 break;
  70 #endif
  71                         if (found_rhdr)
  72                                 return offset;
  73                         break;
  74                 default:
  75                         return offset;
  76                 }
  77
  78                 if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
  79                         return -EINVAL;
  80
  81                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
  82                                                  offset);
  83                 offset += ipv6_optlen(exthdr);
  84                 if (offset > IPV6_MAXPLEN)
  85                         return -EINVAL;
  86                 *nexthdr = &exthdr->nexthdr;
  87         }
  88
  89         return -EINVAL;
  90 }
  91 EXPORT_SYMBOL(ip6_find_1stfragopt);
  92
  93 #if IS_ENABLED(CONFIG_IPV6)
  94 int ip6_dst_hoplimit(struct dst_entry *dst)
  95 {
  96         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
  97         if (hoplimit == 0) {
  98                 struct net_device *dev = dst->dev;
  99                 struct inet6_dev *idev;
 100
 101                 rcu_read_lock();
 102                 idev = __in6_dev_get(dev);
 103                 if (idev)
 104                         hoplimit = idev->cnf.hop_limit;
 105                 else
 106                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 107                 rcu_read_unlock();
 108         }
 109         return hoplimit;
 110 }
 111 EXPORT_SYMBOL(ip6_dst_hoplimit);
 112 #endif
 113
 114 int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 115 {
 116         int len;
 117
 118         len = skb->len - sizeof(struct ipv6hdr);
 119         if (len > IPV6_MAXPLEN)
 120                 len = 0;
 121         ipv6_hdr(skb)->payload_len = htons(len);
 122         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 123
 124         /* if egress device is enslaved to an L3 master device pass the
 125          * skb to its handler for processing
 126          */
 127         skb = l3mdev_ip6_out(sk, skb);
 128         if (unlikely(!skb))
 129                 return 0;
 130
 131         skb->protocol = htons(ETH_P_IPV6);
 132
 133         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 134                        net, sk, skb, NULL, skb_dst(skb)->dev,
 135                        dst_output);
 136 }
 137 EXPORT_SYMBOL_GPL(__ip6_local_out);
 138
 139 int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 140 {
 141         int err;
 142
 143         err = __ip6_local_out(net, sk, skb);
 144         if (likely(err == 1))
 145                 err = dst_output(net, sk, skb);
 146
 147         return err;
 148 }
 149 EXPORT_SYMBOL_GPL(ip6_local_out);