LXR linux/net/ipv6/output

   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
  12u32 __ipv6_select_ident(u32 hashrnd, struct in6_addr *dst, struct in6_addr *src)
  13{
  14        u32 hash, id;
  15
  16        hash = __ipv6_addr_jhash(dst, hashrnd);
  17        hash = __ipv6_addr_jhash(src, hash);
  18
  19        /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
  20         * set the hight order instead thus minimizing possible future
  21         * collisions.
  22         */
  23        id = ip_idents_reserve(hash, 1);
  24        if (unlikely(!id))
  25                id = 1 << 31;
  26
  27        return id;
  28}
  29
  30/* This function exists only for tap drivers that must support broken
  31 * clients requesting UFO without specifying an IPv6 fragment ID.
  32 *
  33 * This is similar to ipv6_select_ident() but we use an independent hash
  34 * seed to limit information leakage.
  35 *
  36 * The network header must be set before calling this.
  37 */
  38void ipv6_proxy_select_ident(struct sk_buff *skb)
  39{
  40        static u32 ip6_proxy_idents_hashrnd __read_mostly;
  41        struct in6_addr buf[2];
  42        struct in6_addr *addrs;
  43        u32 id;
  44
  45        addrs = skb_header_pointer(skb,
  46                                   skb_network_offset(skb) +
  47                                   offsetof(struct ipv6hdr, saddr),
  48                                   sizeof(buf), buf);
  49        if (!addrs)
  50                return;
  51
  52        net_get_random_once(&ip6_proxy_idents_hashrnd,
  53                            sizeof(ip6_proxy_idents_hashrnd));
  54
  55        id = __ipv6_select_ident(ip6_proxy_idents_hashrnd,
  56                                 &addrs[1], &addrs[0]);
  57        skb_shinfo(skb)->ip6_frag_id = id;
  58}
  59EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  60
  61void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
  62{
  63        static u32 ip6_idents_hashrnd __read_mostly;
  64        u32 id;
  65
  66        net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
  67
  68        id = __ipv6_select_ident(ip6_idents_hashrnd, &rt->rt6i_dst.addr,
  69                                 &rt->rt6i_src.addr);
  70        fhdr->identification = htonl(id);
  71}
  72EXPORT_SYMBOL(ipv6_select_ident);
  73
  74int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
  75{
  76        u16 offset = sizeof(struct ipv6hdr);
  77        struct ipv6_opt_hdr *exthdr =
  78                                (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
  79        unsigned int packet_len = skb_tail_pointer(skb) -
  80                skb_network_header(skb);
  81        int found_rhdr = 0;
  82        *nexthdr = &ipv6_hdr(skb)->nexthdr;
  83
  84        while (offset + 1 <= packet_len) {
  85
  86                switch (**nexthdr) {
  87
  88                case NEXTHDR_HOP:
  89                        break;
  90                case NEXTHDR_ROUTING:
  91                        found_rhdr = 1;
  92                        break;
  93                case NEXTHDR_DEST:
  94#if IS_ENABLED(CONFIG_IPV6_MIP6)
  95                        if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
  96                                break;
  97#endif
  98                        if (found_rhdr)
  99                                return offset;
 100                        break;
 101                default:
 102                        return offset;
 103                }
 104
 105                offset += ipv6_optlen(exthdr);
 106                *nexthdr = &exthdr->nexthdr;
 107                exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 108                                                 offset);
 109        }
 110
 111        return offset;
 112}
 113EXPORT_SYMBOL(ip6_find_1stfragopt);
 114
 115#if IS_ENABLED(CONFIG_IPV6)
 116int ip6_dst_hoplimit(struct dst_entry *dst)
 117{
 118        int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
 119        if (hoplimit == 0) {
 120                struct net_device *dev = dst->dev;
 121                struct inet6_dev *idev;
 122
 123                rcu_read_lock();
 124                idev = __in6_dev_get(dev);
 125                if (idev)
 126                        hoplimit = idev->cnf.hop_limit;
 127                else
 128                        hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
 129                rcu_read_unlock();
 130        }
 131        return hoplimit;
 132}
 133EXPORT_SYMBOL(ip6_dst_hoplimit);
 134#endif
 135
 136int __ip6_local_out(struct sk_buff *skb)
 137{
 138        int len;
 139
 140        len = skb->len - sizeof(struct ipv6hdr);
 141        if (len > IPV6_MAXPLEN)
 142                len = 0;
 143        ipv6_hdr(skb)->payload_len = htons(len);
 144        IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 145
 146        return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL,
 147                       skb_dst(skb)->dev, dst_output);
 148}
 149EXPORT_SYMBOL_GPL(__ip6_local_out);
 150
 151int ip6_local_out(struct sk_buff *skb)
 152{
 153        int err;
 154
 155        err = __ip6_local_out(skb);
 156        if (likely(err == 1))
 157                err = dst_output(skb);
 158
 159        return err;
 160}
 161EXPORT_SYMBOL_GPL(ip6_local_out);
 162