net/ipv6/output_core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * IPv6 library code, needed by static components when full IPv6 support is
   4  * not configured or static.  These functions are needed by GSO/GRO implementation.
   5  */
   6 #include <linux/export.h>
   7 #include <net/ip.h>
   8 #include <net/ipv6.h>
   9 #include <net/ip6_fib.h>
  10 #include <net/addrconf.h>
  11 #include <net/secure_seq.h>
  12 #include <linux/netfilter.h>
  13
  14 static u32 __ipv6_select_ident(struct net *net,
  15                                const struct in6_addr *dst,
  16                                const struct in6_addr *src)
  17 {
  18         u32 id;
  19
  20         do {
  21                 id = prandom_u32();
  22         } while (!id);
  23
  24         return id;
  25 }
  26
  27 /* This function exists only for tap drivers that must support broken
  28  * clients requesting UFO without specifying an IPv6 fragment ID.
  29  *
  30  * This is similar to ipv6_select_ident() but we use an independent hash
  31  * seed to limit information leakage.
  32  *
  33  * The network header must be set before calling this.
  34  */
  35 __be32 ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
  36 {
  37         struct in6_addr buf[2];
  38         struct in6_addr *addrs;
  39         u32 id;
  40
  41         addrs = skb_header_pointer(skb,
  42                                    skb_network_offset(skb) +
  43                                    offsetof(struct ipv6hdr, saddr),
  44                                    sizeof(buf), buf);
  45         if (!addrs)
  46                 return 0;
  47
  48         id = __ipv6_select_ident(net, &addrs[1], &addrs[0]);
  49         return htonl(id);
  50 }
  51 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  52
  53 __be32 ipv6_select_ident(struct net *net,
  54                          const struct in6_addr *daddr,
  55                          const struct in6_addr *saddr)
  56 {
  57         u32 id;
  58
  59         id = __ipv6_select_ident(net, daddr, saddr);
  60         return htonl(id);
  61 }
  62 EXPORT_SYMBOL(ipv6_select_ident);
  63
  64 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  65 {
  66         unsigned int offset = sizeof(struct ipv6hdr);
  67         unsigned int packet_len = skb_tail_pointer(skb) -
  68                 skb_network_header(skb);
  69         int found_rhdr = 0;
  70         *nexthdr = &ipv6_hdr(skb)->nexthdr;
  71
  72         while (offset <= packet_len) {
  73                 struct ipv6_opt_hdr *exthdr;
  74
  75                 switch (**nexthdr) {
  76
  77                 case NEXTHDR_HOP:
  78                         break;
  79                 case NEXTHDR_ROUTING:
  80                         found_rhdr = 1;
  81                         break;
  82                 case NEXTHDR_DEST:
  83 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  84                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  85                                 break;
  86 #endif
  87                         if (found_rhdr)
  88                                 return offset;
  89                         break;
  90                 default:
  91                         return offset;
  92                 }
  93
  94                 if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
  95                         return -EINVAL;
  96
  97                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
  98                                                  offset);
  99                 offset += ipv6_optlen(exthdr);
 100                 if (offset > IPV6_MAXPLEN)
 101                         return -EINVAL;
 102                 *nexthdr = &exthdr->nexthdr;
 103         }
 104
 105         return -EINVAL;
 106 }
 107 EXPORT_SYMBOL(ip6_find_1stfragopt);
 108
 109 #if IS_ENABLED(CONFIG_IPV6)
 110 int ip6_dst_hoplimit(struct dst_entry *dst)
 111 {
 112         int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 113         if (hoplimit == 0) {
 114                 struct net_device *dev = dst->dev;
 115                 struct inet6_dev *idev;
 116
 117                 rcu_read_lock();
 118                 idev = __in6_dev_get(dev);
 119                 if (idev)
 120                         hoplimit = idev->cnf.hop_limit;
 121                 else
 122                         hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 123                 rcu_read_unlock();
 124         }
 125         return hoplimit;
 126 }
 127 EXPORT_SYMBOL(ip6_dst_hoplimit);
 128 #endif
 129
 130 int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 131 {
 132         int len;
 133
 134         len = skb->len - sizeof(struct ipv6hdr);
 135         if (len > IPV6_MAXPLEN)
 136                 len = 0;
 137         ipv6_hdr(skb)->payload_len = htons(len);
 138         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 139
 140         /* if egress device is enslaved to an L3 master device pass the
 141          * skb to its handler for processing
 142          */
 143         skb = l3mdev_ip6_out(sk, skb);
 144         if (unlikely(!skb))
 145                 return 0;
 146
 147         skb->protocol = htons(ETH_P_IPV6);
 148
 149         return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 150                        net, sk, skb, NULL, skb_dst(skb)->dev,
 151                        dst_output);
 152 }
 153 EXPORT_SYMBOL_GPL(__ip6_local_out);
 154
 155 int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 156 {
 157         int err;
 158
 159         err = __ip6_local_out(net, sk, skb);
 160         if (likely(err == 1))
 161                 err = dst_output(net, sk, skb);
 162
 163         return err;
 164 }
 165 EXPORT_SYMBOL_GPL(ip6_local_out);