linux/net/ipv6/fou6.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2#include <linux/module.h>
   3#include <linux/errno.h>
   4#include <linux/socket.h>
   5#include <linux/skbuff.h>
   6#include <linux/ip.h>
   7#include <linux/udp.h>
   8#include <linux/icmpv6.h>
   9#include <linux/types.h>
  10#include <linux/kernel.h>
  11#include <net/fou.h>
  12#include <net/ip.h>
  13#include <net/ip6_tunnel.h>
  14#include <net/ip6_checksum.h>
  15#include <net/protocol.h>
  16#include <net/udp.h>
  17#include <net/udp_tunnel.h>
  18
  19#if IS_ENABLED(CONFIG_IPV6_FOU_TUNNEL)
  20
  21static void fou6_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e,
  22                           struct flowi6 *fl6, u8 *protocol, __be16 sport)
  23{
  24        struct udphdr *uh;
  25
  26        skb_push(skb, sizeof(struct udphdr));
  27        skb_reset_transport_header(skb);
  28
  29        uh = udp_hdr(skb);
  30
  31        uh->dest = e->dport;
  32        uh->source = sport;
  33        uh->len = htons(skb->len);
  34        udp6_set_csum(!(e->flags & TUNNEL_ENCAP_FLAG_CSUM6), skb,
  35                      &fl6->saddr, &fl6->daddr, skb->len);
  36
  37        *protocol = IPPROTO_UDP;
  38}
  39
  40static int fou6_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
  41                             u8 *protocol, struct flowi6 *fl6)
  42{
  43        __be16 sport;
  44        int err;
  45        int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM6 ?
  46                SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
  47
  48        err = __fou_build_header(skb, e, protocol, &sport, type);
  49        if (err)
  50                return err;
  51
  52        fou6_build_udp(skb, e, fl6, protocol, sport);
  53
  54        return 0;
  55}
  56
  57static int gue6_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
  58                             u8 *protocol, struct flowi6 *fl6)
  59{
  60        __be16 sport;
  61        int err;
  62        int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM6 ?
  63                SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
  64
  65        err = __gue_build_header(skb, e, protocol, &sport, type);
  66        if (err)
  67                return err;
  68
  69        fou6_build_udp(skb, e, fl6, protocol, sport);
  70
  71        return 0;
  72}
  73
  74static int gue6_err_proto_handler(int proto, struct sk_buff *skb,
  75                                  struct inet6_skb_parm *opt,
  76                                  u8 type, u8 code, int offset, __be32 info)
  77{
  78        const struct inet6_protocol *ipprot;
  79
  80        ipprot = rcu_dereference(inet6_protos[proto]);
  81        if (ipprot && ipprot->err_handler) {
  82                if (!ipprot->err_handler(skb, opt, type, code, offset, info))
  83                        return 0;
  84        }
  85
  86        return -ENOENT;
  87}
  88
  89static int gue6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  90                    u8 type, u8 code, int offset, __be32 info)
  91{
  92        int transport_offset = skb_transport_offset(skb);
  93        struct guehdr *guehdr;
  94        size_t len, optlen;
  95        int ret;
  96
  97        len = sizeof(struct udphdr) + sizeof(struct guehdr);
  98        if (!pskb_may_pull(skb, transport_offset + len))
  99                return -EINVAL;
 100
 101        guehdr = (struct guehdr *)&udp_hdr(skb)[1];
 102
 103        switch (guehdr->version) {
 104        case 0: /* Full GUE header present */
 105                break;
 106        case 1: {
 107                /* Direct encasulation of IPv4 or IPv6 */
 108                skb_set_transport_header(skb, -(int)sizeof(struct icmp6hdr));
 109
 110                switch (((struct iphdr *)guehdr)->version) {
 111                case 4:
 112                        ret = gue6_err_proto_handler(IPPROTO_IPIP, skb, opt,
 113                                                     type, code, offset, info);
 114                        goto out;
 115                case 6:
 116                        ret = gue6_err_proto_handler(IPPROTO_IPV6, skb, opt,
 117                                                     type, code, offset, info);
 118                        goto out;
 119                default:
 120                        ret = -EOPNOTSUPP;
 121                        goto out;
 122                }
 123        }
 124        default: /* Undefined version */
 125                return -EOPNOTSUPP;
 126        }
 127
 128        if (guehdr->control)
 129                return -ENOENT;
 130
 131        optlen = guehdr->hlen << 2;
 132
 133        if (!pskb_may_pull(skb, transport_offset + len + optlen))
 134                return -EINVAL;
 135
 136        guehdr = (struct guehdr *)&udp_hdr(skb)[1];
 137        if (validate_gue_flags(guehdr, optlen))
 138                return -EINVAL;
 139
 140        /* Handling exceptions for direct UDP encapsulation in GUE would lead to
 141         * recursion. Besides, this kind of encapsulation can't even be
 142         * configured currently. Discard this.
 143         */
 144        if (guehdr->proto_ctype == IPPROTO_UDP ||
 145            guehdr->proto_ctype == IPPROTO_UDPLITE)
 146                return -EOPNOTSUPP;
 147
 148        skb_set_transport_header(skb, -(int)sizeof(struct icmp6hdr));
 149        ret = gue6_err_proto_handler(guehdr->proto_ctype, skb,
 150                                     opt, type, code, offset, info);
 151
 152out:
 153        skb_set_transport_header(skb, transport_offset);
 154        return ret;
 155}
 156
 157
 158static const struct ip6_tnl_encap_ops fou_ip6tun_ops = {
 159        .encap_hlen = fou_encap_hlen,
 160        .build_header = fou6_build_header,
 161        .err_handler = gue6_err,
 162};
 163
 164static const struct ip6_tnl_encap_ops gue_ip6tun_ops = {
 165        .encap_hlen = gue_encap_hlen,
 166        .build_header = gue6_build_header,
 167        .err_handler = gue6_err,
 168};
 169
 170static int ip6_tnl_encap_add_fou_ops(void)
 171{
 172        int ret;
 173
 174        ret = ip6_tnl_encap_add_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
 175        if (ret < 0) {
 176                pr_err("can't add fou6 ops\n");
 177                return ret;
 178        }
 179
 180        ret = ip6_tnl_encap_add_ops(&gue_ip6tun_ops, TUNNEL_ENCAP_GUE);
 181        if (ret < 0) {
 182                pr_err("can't add gue6 ops\n");
 183                ip6_tnl_encap_del_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
 184                return ret;
 185        }
 186
 187        return 0;
 188}
 189
 190static void ip6_tnl_encap_del_fou_ops(void)
 191{
 192        ip6_tnl_encap_del_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
 193        ip6_tnl_encap_del_ops(&gue_ip6tun_ops, TUNNEL_ENCAP_GUE);
 194}
 195
 196#else
 197
 198static int ip6_tnl_encap_add_fou_ops(void)
 199{
 200        return 0;
 201}
 202
 203static void ip6_tnl_encap_del_fou_ops(void)
 204{
 205}
 206
 207#endif
 208
 209static int __init fou6_init(void)
 210{
 211        int ret;
 212
 213        ret = ip6_tnl_encap_add_fou_ops();
 214
 215        return ret;
 216}
 217
 218static void __exit fou6_fini(void)
 219{
 220        ip6_tnl_encap_del_fou_ops();
 221}
 222
 223module_init(fou6_init);
 224module_exit(fou6_fini);
 225MODULE_AUTHOR("Tom Herbert <therbert@google.com>");
 226MODULE_LICENSE("GPL");
 227