LXR linux/net/ipv6/output

   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
  14static 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}
  51EXPORT_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}
  62EXPORT_SYMBOL(ipv6_select_ident);
  63
  64int 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}
 107EXPORT_SYMBOL(ip6_find_1stfragopt);
 108
 109#if IS_ENABLED(CONFIG_IPV6)
 110int 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}
 127EXPORT_SYMBOL(ip6_dst_hoplimit);
 128#endif
 129
 130int __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}
 153EXPORT_SYMBOL_GPL(__ip6_local_out);
 154
 155int 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}
 165EXPORT_SYMBOL_GPL(ip6_local_out);
 166