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                                struct in6_addr *dst, struct in6_addr *src)
  14 {
  15         u32 hash, id;
  16
  17         hash = __ipv6_addr_jhash(dst, hashrnd);
  18         hash = __ipv6_addr_jhash(src, hash);
  19         hash ^= net_hash_mix(net);
  20
  21         /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
  22          * set the hight order instead thus minimizing possible future
  23          * collisions.
  24          */
  25         id = ip_idents_reserve(hash, 1);
  26         if (unlikely(!id))
  27                 id = 1 << 31;
  28
  29         return id;
  30 }
  31
  32 /* This function exists only for tap drivers that must support broken
  33  * clients requesting UFO without specifying an IPv6 fragment ID.
  34  *
  35  * This is similar to ipv6_select_ident() but we use an independent hash
  36  * seed to limit information leakage.
  37  *
  38  * The network header must be set before calling this.
  39  */
  40 void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
  41 {
  42         static u32 ip6_proxy_idents_hashrnd __read_mostly;
  43         struct in6_addr buf[2];
  44         struct in6_addr *addrs;
  45         u32 id;
  46
  47         addrs = skb_header_pointer(skb,
  48                                    skb_network_offset(skb) +
  49                                    offsetof(struct ipv6hdr, saddr),
  50                                    sizeof(buf), buf);
  51         if (!addrs)
  52                 return;
  53
  54         net_get_random_once(&ip6_proxy_idents_hashrnd,
  55                             sizeof(ip6_proxy_idents_hashrnd));
  56
  57         id = __ipv6_select_ident(net, ip6_proxy_idents_hashrnd,
  58                                  &addrs[1], &addrs[0]);
  59         skb_shinfo(skb)->ip6_frag_id = htonl(id);
  60 }
  61 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  62
  63 void ipv6_select_ident(struct net *net, struct frag_hdr *fhdr,
  64                        struct rt6_info *rt)
  65 {
  66         static u32 ip6_idents_hashrnd __read_mostly;
  67         u32 id;
  68
  69         net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
  70
  71         id = __ipv6_select_ident(net, ip6_idents_hashrnd, &rt->rt6i_dst.addr,
  72                                  &rt->rt6i_src.addr);
  73         fhdr->identification = htonl(id);
  74 }
  75 EXPORT_SYMBOL(ipv6_select_ident);
  76
  77 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  78 {
  79         u16 offset = sizeof(struct ipv6hdr);
  80         struct ipv6_opt_hdr *exthdr =
  81                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  82         unsigned int packet_len = skb_tail_pointer(skb) -
  83                 skb_network_header(skb);
  84         int found_rhdr = 0;
  85         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  86
  87         while (offset + 1 <= packet_len) {
  88
  89                 switch (**nexthdr) {
  90
  91                 case NEXTHDR_HOP:
  92                         break;
  93                 case NEXTHDR_ROUTING:
  94                         found_rhdr = 1;
  95                         break;
  96                 case NEXTHDR_DEST:
  97 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  98                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  99                                 break;
 100 #endif
 101                         if (found_rhdr)
 102                                 return offset;
 103                         break;
 104                 default:
 105                         return offset;
 106                 }
 107
 108                 offset += ipv6_optlen(exthdr);
 109                 *nexthdr = &exthdr->nexthdr;
 110                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 111                                                  offset);
 112         }
 113
 114         return offset;
 115 }
 116 EXPORT_SYMBOL(ip6_find_1stfragopt);
 117
 118 #if IS_ENABLED(CONFIG_IPV6)
 119 int ip6_dst_hoplimit(struct dst_entry *dst)
 120 {
 121         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 122         if (hoplimit == 0) {
 123                 struct net_device *dev = dst->dev;
 124                 struct inet6_dev *idev;
 125
 126                 rcu_read_lock();
 127                 idev = __in6_dev_get(dev);
 128                 if (idev)
 129                         hoplimit = idev->cnf.hop_limit;
 130                 else
 131                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 132                 rcu_read_unlock();
 133         }
 134         return hoplimit;
 135 }
 136 EXPORT_SYMBOL(ip6_dst_hoplimit);
 137 #endif
 138
 139 static int __ip6_local_out_sk(struct sock *sk, struct sk_buff *skb)
 140 {
 141         int len;
 142
 143         len = skb->len - sizeof(struct ipv6hdr);
 144         if (len > IPV6_MAXPLEN)
 145                 len = 0;
 146         ipv6_hdr(skb)->payload_len = htons(len);
 147         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 148
 149         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, sk, skb,
 150                        NULL, skb_dst(skb)->dev, dst_output_sk);
 151 }
 152
 153 int __ip6_local_out(struct sk_buff *skb)
 154 {
 155         return __ip6_local_out_sk(skb->sk, skb);
 156 }
 157 EXPORT_SYMBOL_GPL(__ip6_local_out);
 158
 159 int ip6_local_out_sk(struct sock *sk, struct sk_buff *skb)
 160 {
 161         int err;
 162
 163         err = __ip6_local_out_sk(sk, skb);
 164         if (likely(err == 1))
 165                 err = dst_output_sk(sk, skb);
 166
 167         return err;
 168 }
 169 EXPORT_SYMBOL_GPL(ip6_local_out_sk);
 170
 171 int ip6_local_out(struct sk_buff *skb)
 172 {
 173         return ip6_local_out_sk(skb->sk, skb);
 174 }
 175 EXPORT_SYMBOL_GPL(ip6_local_out);