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
  12static 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 */
  40void 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}
  61EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
  62
  63void 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}
  75EXPORT_SYMBOL(ipv6_select_ident);
  76
  77int 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}
 116EXPORT_SYMBOL(ip6_find_1stfragopt);
 117
 118#if IS_ENABLED(CONFIG_IPV6)
 119int 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}
 136EXPORT_SYMBOL(ip6_dst_hoplimit);
 137#endif
 138
 139static 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
 153int __ip6_local_out(struct sk_buff *skb)
 154{
 155        return __ip6_local_out_sk(skb->sk, skb);
 156}
 157EXPORT_SYMBOL_GPL(__ip6_local_out);
 158
 159int 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}
 169EXPORT_SYMBOL_GPL(ip6_local_out_sk);
 170
 171int ip6_local_out(struct sk_buff *skb)
 172{
 173        return ip6_local_out_sk(skb->sk, skb);
 174}
 175EXPORT_SYMBOL_GPL(ip6_local_out);
 176