net/ipv6/xfrm6_protocol.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* xfrm6_protocol.c - Generic xfrm protocol multiplexer for ipv6.
   3  *
   4  * Copyright (C) 2013 secunet Security Networks AG
   5  *
   6  * Author:
   7  * Steffen Klassert <steffen.klassert@secunet.com>
   8  *
   9  * Based on:
  10  * net/ipv4/xfrm4_protocol.c
  11  */
  12
  13 #include <linux/init.h>
  14 #include <linux/mutex.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/icmpv6.h>
  17 #include <net/ip6_route.h>
  18 #include <net/ipv6.h>
  19 #include <net/protocol.h>
  20 #include <net/xfrm.h>
  21
  22 static struct xfrm6_protocol __rcu *esp6_handlers __read_mostly;
  23 static struct xfrm6_protocol __rcu *ah6_handlers __read_mostly;
  24 static struct xfrm6_protocol __rcu *ipcomp6_handlers __read_mostly;
  25 static DEFINE_MUTEX(xfrm6_protocol_mutex);
  26
  27 static inline struct xfrm6_protocol __rcu **proto_handlers(u8 protocol)
  28 {
  29         switch (protocol) {
  30         case IPPROTO_ESP:
  31                 return &esp6_handlers;
  32         case IPPROTO_AH:
  33                 return &ah6_handlers;
  34         case IPPROTO_COMP:
  35                 return &ipcomp6_handlers;
  36         }
  37
  38         return NULL;
  39 }
  40
  41 #define for_each_protocol_rcu(head, handler)            \
  42         for (handler = rcu_dereference(head);           \
  43              handler != NULL;                           \
  44              handler = rcu_dereference(handler->next))  \
  45
  46 static int xfrm6_rcv_cb(struct sk_buff *skb, u8 protocol, int err)
  47 {
  48         int ret;
  49         struct xfrm6_protocol *handler;
  50         struct xfrm6_protocol __rcu **head = proto_handlers(protocol);
  51
  52         if (!head)
  53                 return 0;
  54
  55         for_each_protocol_rcu(*proto_handlers(protocol), handler)
  56                 if ((ret = handler->cb_handler(skb, err)) <= 0)
  57                         return ret;
  58
  59         return 0;
  60 }
  61
  62 int xfrm6_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
  63                     int encap_type)
  64 {
  65         int ret;
  66         struct xfrm6_protocol *handler;
  67         struct xfrm6_protocol __rcu **head = proto_handlers(nexthdr);
  68
  69         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
  70         XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
  71         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
  72
  73         if (!head)
  74                 goto out;
  75
  76         if (!skb_dst(skb)) {
  77                 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
  78                 int flags = RT6_LOOKUP_F_HAS_SADDR;
  79                 struct dst_entry *dst;
  80                 struct flowi6 fl6 = {
  81                         .flowi6_iif   = skb->dev->ifindex,
  82                         .daddr        = ip6h->daddr,
  83                         .saddr        = ip6h->saddr,
  84                         .flowlabel    = ip6_flowinfo(ip6h),
  85                         .flowi6_mark  = skb->mark,
  86                         .flowi6_proto = ip6h->nexthdr,
  87                 };
  88
  89                 dst = ip6_route_input_lookup(dev_net(skb->dev), skb->dev, &fl6,
  90                                              skb, flags);
  91                 if (dst->error)
  92                         goto drop;
  93                 skb_dst_set(skb, dst);
  94         }
  95
  96         for_each_protocol_rcu(*head, handler)
  97                 if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
  98                         return ret;
  99
 100 out:
 101         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 102
 103 drop:
 104         kfree_skb(skb);
 105         return 0;
 106 }
 107 EXPORT_SYMBOL(xfrm6_rcv_encap);
 108
 109 static int xfrm6_esp_rcv(struct sk_buff *skb)
 110 {
 111         int ret;
 112         struct xfrm6_protocol *handler;
 113
 114         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 115
 116         for_each_protocol_rcu(esp6_handlers, handler)
 117                 if ((ret = handler->handler(skb)) != -EINVAL)
 118                         return ret;
 119
 120         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 121
 122         kfree_skb(skb);
 123         return 0;
 124 }
 125
 126 static int xfrm6_esp_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 127                           u8 type, u8 code, int offset, __be32 info)
 128 {
 129         struct xfrm6_protocol *handler;
 130
 131         for_each_protocol_rcu(esp6_handlers, handler)
 132                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 133                         return 0;
 134
 135         return -ENOENT;
 136 }
 137
 138 static int xfrm6_ah_rcv(struct sk_buff *skb)
 139 {
 140         int ret;
 141         struct xfrm6_protocol *handler;
 142
 143         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 144
 145         for_each_protocol_rcu(ah6_handlers, handler)
 146                 if ((ret = handler->handler(skb)) != -EINVAL)
 147                         return ret;
 148
 149         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 150
 151         kfree_skb(skb);
 152         return 0;
 153 }
 154
 155 static int xfrm6_ah_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 156                          u8 type, u8 code, int offset, __be32 info)
 157 {
 158         struct xfrm6_protocol *handler;
 159
 160         for_each_protocol_rcu(ah6_handlers, handler)
 161                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 162                         return 0;
 163
 164         return -ENOENT;
 165 }
 166
 167 static int xfrm6_ipcomp_rcv(struct sk_buff *skb)
 168 {
 169         int ret;
 170         struct xfrm6_protocol *handler;
 171
 172         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
 173
 174         for_each_protocol_rcu(ipcomp6_handlers, handler)
 175                 if ((ret = handler->handler(skb)) != -EINVAL)
 176                         return ret;
 177
 178         icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
 179
 180         kfree_skb(skb);
 181         return 0;
 182 }
 183
 184 static int xfrm6_ipcomp_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 185                              u8 type, u8 code, int offset, __be32 info)
 186 {
 187         struct xfrm6_protocol *handler;
 188
 189         for_each_protocol_rcu(ipcomp6_handlers, handler)
 190                 if (!handler->err_handler(skb, opt, type, code, offset, info))
 191                         return 0;
 192
 193         return -ENOENT;
 194 }
 195
 196 static const struct inet6_protocol esp6_protocol = {
 197         .handler        =       xfrm6_esp_rcv,
 198         .err_handler    =       xfrm6_esp_err,
 199         .flags          =       INET6_PROTO_NOPOLICY,
 200 };
 201
 202 static const struct inet6_protocol ah6_protocol = {
 203         .handler        =       xfrm6_ah_rcv,
 204         .err_handler    =       xfrm6_ah_err,
 205         .flags          =       INET6_PROTO_NOPOLICY,
 206 };
 207
 208 static const struct inet6_protocol ipcomp6_protocol = {
 209         .handler        =       xfrm6_ipcomp_rcv,
 210         .err_handler    =       xfrm6_ipcomp_err,
 211         .flags          =       INET6_PROTO_NOPOLICY,
 212 };
 213
 214 static const struct xfrm_input_afinfo xfrm6_input_afinfo = {
 215         .family         =       AF_INET6,
 216         .callback       =       xfrm6_rcv_cb,
 217 };
 218
 219 static inline const struct inet6_protocol *netproto(unsigned char protocol)
 220 {
 221         switch (protocol) {
 222         case IPPROTO_ESP:
 223                 return &esp6_protocol;
 224         case IPPROTO_AH:
 225                 return &ah6_protocol;
 226         case IPPROTO_COMP:
 227                 return &ipcomp6_protocol;
 228         }
 229
 230         return NULL;
 231 }
 232
 233 int xfrm6_protocol_register(struct xfrm6_protocol *handler,
 234                             unsigned char protocol)
 235 {
 236         struct xfrm6_protocol __rcu **pprev;
 237         struct xfrm6_protocol *t;
 238         bool add_netproto = false;
 239         int ret = -EEXIST;
 240         int priority = handler->priority;
 241
 242         if (!proto_handlers(protocol) || !netproto(protocol))
 243                 return -EINVAL;
 244
 245         mutex_lock(&xfrm6_protocol_mutex);
 246
 247         if (!rcu_dereference_protected(*proto_handlers(protocol),
 248                                        lockdep_is_held(&xfrm6_protocol_mutex)))
 249                 add_netproto = true;
 250
 251         for (pprev = proto_handlers(protocol);
 252              (t = rcu_dereference_protected(*pprev,
 253                         lockdep_is_held(&xfrm6_protocol_mutex))) != NULL;
 254              pprev = &t->next) {
 255                 if (t->priority < priority)
 256                         break;
 257                 if (t->priority == priority)
 258                         goto err;
 259         }
 260
 261         handler->next = *pprev;
 262         rcu_assign_pointer(*pprev, handler);
 263
 264         ret = 0;
 265
 266 err:
 267         mutex_unlock(&xfrm6_protocol_mutex);
 268
 269         if (add_netproto) {
 270                 if (inet6_add_protocol(netproto(protocol), protocol)) {
 271                         pr_err("%s: can't add protocol\n", __func__);
 272                         ret = -EAGAIN;
 273                 }
 274         }
 275
 276         return ret;
 277 }
 278 EXPORT_SYMBOL(xfrm6_protocol_register);
 279
 280 int xfrm6_protocol_deregister(struct xfrm6_protocol *handler,
 281                               unsigned char protocol)
 282 {
 283         struct xfrm6_protocol __rcu **pprev;
 284         struct xfrm6_protocol *t;
 285         int ret = -ENOENT;
 286
 287         if (!proto_handlers(protocol) || !netproto(protocol))
 288                 return -EINVAL;
 289
 290         mutex_lock(&xfrm6_protocol_mutex);
 291
 292         for (pprev = proto_handlers(protocol);
 293              (t = rcu_dereference_protected(*pprev,
 294                         lockdep_is_held(&xfrm6_protocol_mutex))) != NULL;
 295              pprev = &t->next) {
 296                 if (t == handler) {
 297                         *pprev = handler->next;
 298                         ret = 0;
 299                         break;
 300                 }
 301         }
 302
 303         if (!rcu_dereference_protected(*proto_handlers(protocol),
 304                                        lockdep_is_held(&xfrm6_protocol_mutex))) {
 305                 if (inet6_del_protocol(netproto(protocol), protocol) < 0) {
 306                         pr_err("%s: can't remove protocol\n", __func__);
 307                         ret = -EAGAIN;
 308                 }
 309         }
 310
 311         mutex_unlock(&xfrm6_protocol_mutex);
 312
 313         synchronize_net();
 314
 315         return ret;
 316 }
 317 EXPORT_SYMBOL(xfrm6_protocol_deregister);
 318
 319 int __init xfrm6_protocol_init(void)
 320 {
 321         return xfrm_input_register_afinfo(&xfrm6_input_afinfo);
 322 }
 323
 324 void xfrm6_protocol_fini(void)
 325 {
 326         xfrm_input_unregister_afinfo(&xfrm6_input_afinfo);
 327 }