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 /* This function exists only for tap drivers that must support broken
  35  * clients requesting UFO without specifying an IPv6 fragment ID.
  36  *
  37  * This is similar to ipv6_select_ident() but we use an independent hash
  38  * seed to limit information leakage.
  39  *
  40  * The network header must be set before calling this.
  41  */
  42 void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
  43 {
  44         static u32 ip6_proxy_idents_hashrnd __read_mostly;
  45         struct in6_addr buf[2];
  46         struct in6_addr *addrs;
  47         u32 id;
  48
  49         addrs = skb_header_pointer(skb,
  50                                    skb_network_offset(skb) +
  51                                    offsetof(struct ipv6hdr, saddr),
  52                                    sizeof(buf), buf);
  53         if (!addrs)
  54                 return;
  55
  56         net_get_random_once(&ip6_proxy_idents_hashrnd,
  57                             sizeof(ip6_proxy_idents_hashrnd));
  58
  59         id = __ipv6_select_ident(net, ip6_proxy_idents_hashrnd,
  60                                  &addrs[1], &addrs[0]);
  61         skb_shinfo(skb)->ip6_frag_id = htonl(id);
  62 }
  63 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  64
  65 __be32 ipv6_select_ident(struct net *net,
  66                          const struct in6_addr *daddr,
  67                          const struct in6_addr *saddr)
  68 {
  69         static u32 ip6_idents_hashrnd __read_mostly;
  70         u32 id;
  71
  72         net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
  73
  74         id = __ipv6_select_ident(net, ip6_idents_hashrnd, daddr, saddr);
  75         return htonl(id);
  76 }
  77 EXPORT_SYMBOL(ipv6_select_ident);
  78
  79 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  80 {
  81         u16 offset = sizeof(struct ipv6hdr);
  82         struct ipv6_opt_hdr *exthdr =
  83                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  84         unsigned int packet_len = skb_tail_pointer(skb) -
  85                 skb_network_header(skb);
  86         int found_rhdr = 0;
  87         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  88
  89         while (offset + 1 <= packet_len) {
  90
  91                 switch (**nexthdr) {
  92
  93                 case NEXTHDR_HOP:
  94                         break;
  95                 case NEXTHDR_ROUTING:
  96                         found_rhdr = 1;
  97                         break;
  98                 case NEXTHDR_DEST:
  99 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 100                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 101                                 break;
 102 #endif
 103                         if (found_rhdr)
 104                                 return offset;
 105                         break;
 106                 default:
 107                         return offset;
 108                 }
 109
 110                 offset += ipv6_optlen(exthdr);
 111                 *nexthdr = &exthdr->nexthdr;
 112                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 113                                                  offset);
 114         }
 115
 116         return offset;
 117 }
 118 EXPORT_SYMBOL(ip6_find_1stfragopt);
 119
 120 #if IS_ENABLED(CONFIG_IPV6)
 121 int ip6_dst_hoplimit(struct dst_entry *dst)
 122 {
 123         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 124         if (hoplimit == 0) {
 125                 struct net_device *dev = dst->dev;
 126                 struct inet6_dev *idev;
 127
 128                 rcu_read_lock();
 129                 idev = __in6_dev_get(dev);
 130                 if (idev)
 131                         hoplimit = idev->cnf.hop_limit;
 132                 else
 133                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 134                 rcu_read_unlock();
 135         }
 136         return hoplimit;
 137 }
 138 EXPORT_SYMBOL(ip6_dst_hoplimit);
 139 #endif
 140
 141 int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 142 {
 143         int len;
 144
 145         len = skb->len - sizeof(struct ipv6hdr);
 146         if (len > IPV6_MAXPLEN)
 147                 len = 0;
 148         ipv6_hdr(skb)->payload_len = htons(len);
 149         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 150
 151         /* if egress device is enslaved to an L3 master device pass the
 152          * skb to its handler for processing
 153          */
 154         skb = l3mdev_ip6_out(sk, skb);
 155         if (unlikely(!skb))
 156                 return 0;
 157
 158         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 159                        net, sk, skb, NULL, skb_dst(skb)->dev,
 160                        dst_output);
 161 }
 162 EXPORT_SYMBOL_GPL(__ip6_local_out);
 163
 164 int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 165 {
 166         int err;
 167
 168         err = __ip6_local_out(net, sk, skb);
 169         if (likely(err == 1))
 170                 err = dst_output(net, sk, skb);
 171
 172         return err;
 173 }
 174 EXPORT_SYMBOL_GPL(ip6_local_out);