net/ipv6/xfrm6_input.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * xfrm6_input.c: based on net/ipv4/xfrm4_input.c
   4  *
   5  * Authors:
   6  *      Mitsuru KANDA @USAGI
   7  *      Kazunori MIYAZAWA @USAGI
   8  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   9  *      YOSHIFUJI Hideaki @USAGI
  10  *              IPv6 support
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/string.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/netfilter_ipv6.h>
  17 #include <net/ipv6.h>
  18 #include <net/xfrm.h>
  19 #include <net/protocol.h>
  20 #include <net/gro.h>
  21
  22 int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
  23                   struct ip6_tnl *t)
  24 {
  25         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
  26         XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
  27         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
  28         return xfrm_input(skb, nexthdr, spi, 0);
  29 }
  30 EXPORT_SYMBOL(xfrm6_rcv_spi);
  31
  32 static int xfrm6_transport_finish2(struct net *net, struct sock *sk,
  33                                    struct sk_buff *skb)
  34 {
  35         if (xfrm_trans_queue(skb, ip6_rcv_finish)) {
  36                 kfree_skb(skb);
  37                 return NET_RX_DROP;
  38         }
  39
  40         return 0;
  41 }
  42
  43 int xfrm6_transport_finish(struct sk_buff *skb, int async)
  44 {
  45         struct xfrm_offload *xo = xfrm_offload(skb);
  46         int nhlen = -skb_network_offset(skb);
  47
  48         skb_network_header(skb)[IP6CB(skb)->nhoff] =
  49                 XFRM_MODE_SKB_CB(skb)->protocol;
  50
  51 #ifndef CONFIG_NETFILTER
  52         if (!async)
  53                 return 1;
  54 #endif
  55
  56         __skb_push(skb, nhlen);
  57         ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
  58         skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
  59
  60         if (xo && (xo->flags & XFRM_GRO)) {
  61                 /* The full l2 header needs to be preserved so that re-injecting the packet at l2
  62                  * works correctly in the presence of vlan tags.
  63                  */
  64                 skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
  65                 skb_reset_network_header(skb);
  66                 skb_reset_transport_header(skb);
  67                 return 0;
  68         }
  69
  70         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
  71                 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
  72                 xfrm6_transport_finish2);
  73         return 0;
  74 }
  75
  76 static int __xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull)
  77 {
  78         struct udp_sock *up = udp_sk(sk);
  79         struct udphdr *uh;
  80         struct ipv6hdr *ip6h;
  81         int len;
  82         int ip6hlen = sizeof(struct ipv6hdr);
  83         __u8 *udpdata;
  84         __be32 *udpdata32;
  85         u16 encap_type;
  86
  87         encap_type = READ_ONCE(up->encap_type);
  88         /* if this is not encapsulated socket, then just return now */
  89         if (!encap_type)
  90                 return 1;
  91
  92         /* If this is a paged skb, make sure we pull up
  93          * whatever data we need to look at. */
  94         len = skb->len - sizeof(struct udphdr);
  95         if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
  96                 return 1;
  97
  98         /* Now we can get the pointers */
  99         uh = udp_hdr(skb);
 100         udpdata = (__u8 *)uh + sizeof(struct udphdr);
 101         udpdata32 = (__be32 *)udpdata;
 102
 103         switch (encap_type) {
 104         default:
 105         case UDP_ENCAP_ESPINUDP:
 106                 /* Check if this is a keepalive packet.  If so, eat it. */
 107                 if (len == 1 && udpdata[0] == 0xff) {
 108                         return -EINVAL;
 109                 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
 110                         /* ESP Packet without Non-ESP header */
 111                         len = sizeof(struct udphdr);
 112                 } else
 113                         /* Must be an IKE packet.. pass it through */
 114                         return 1;
 115                 break;
 116         }
 117
 118         /* At this point we are sure that this is an ESPinUDP packet,
 119          * so we need to remove 'len' bytes from the packet (the UDP
 120          * header and optional ESP marker bytes) and then modify the
 121          * protocol to ESP, and then call into the transform receiver.
 122          */
 123         if (skb_unclone(skb, GFP_ATOMIC))
 124                 return -EINVAL;
 125
 126         /* Now we can update and verify the packet length... */
 127         ip6h = ipv6_hdr(skb);
 128         ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
 129         if (skb->len < ip6hlen + len) {
 130                 /* packet is too small!?! */
 131                 return -EINVAL;
 132         }
 133
 134         /* pull the data buffer up to the ESP header and set the
 135          * transport header to point to ESP.  Keep UDP on the stack
 136          * for later.
 137          */
 138         if (pull) {
 139                 __skb_pull(skb, len);
 140                 skb_reset_transport_header(skb);
 141         } else {
 142                 skb_set_transport_header(skb, len);
 143         }
 144
 145         /* process ESP */
 146         return 0;
 147 }
 148
 149 /* If it's a keepalive packet, then just eat it.
 150  * If it's an encapsulated packet, then pass it to the
 151  * IPsec xfrm input.
 152  * Returns 0 if skb passed to xfrm or was dropped.
 153  * Returns >0 if skb should be passed to UDP.
 154  * Returns <0 if skb should be resubmitted (-ret is protocol)
 155  */
 156 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
 157 {
 158         int ret;
 159
 160         if (skb->protocol == htons(ETH_P_IP))
 161                 return xfrm4_udp_encap_rcv(sk, skb);
 162
 163         ret = __xfrm6_udp_encap_rcv(sk, skb, true);
 164         if (!ret)
 165                 return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0,
 166                                        udp_sk(sk)->encap_type);
 167
 168         if (ret < 0) {
 169                 kfree_skb(skb);
 170                 return 0;
 171         }
 172
 173         return ret;
 174 }
 175
 176 struct sk_buff *xfrm6_gro_udp_encap_rcv(struct sock *sk, struct list_head *head,
 177                                         struct sk_buff *skb)
 178 {
 179         int offset = skb_gro_offset(skb);
 180         const struct net_offload *ops;
 181         struct sk_buff *pp = NULL;
 182         int ret;
 183
 184         if (skb->protocol == htons(ETH_P_IP))
 185                 return xfrm4_gro_udp_encap_rcv(sk, head, skb);
 186
 187         offset = offset - sizeof(struct udphdr);
 188
 189         if (!pskb_pull(skb, offset))
 190                 return NULL;
 191
 192         rcu_read_lock();
 193         ops = rcu_dereference(inet6_offloads[IPPROTO_ESP]);
 194         if (!ops || !ops->callbacks.gro_receive)
 195                 goto out;
 196
 197         ret = __xfrm6_udp_encap_rcv(sk, skb, false);
 198         if (ret)
 199                 goto out;
 200
 201         skb_push(skb, offset);
 202         NAPI_GRO_CB(skb)->proto = IPPROTO_UDP;
 203
 204         pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
 205         rcu_read_unlock();
 206
 207         return pp;
 208
 209 out:
 210         rcu_read_unlock();
 211         skb_push(skb, offset);
 212         NAPI_GRO_CB(skb)->same_flow = 0;
 213         NAPI_GRO_CB(skb)->flush = 1;
 214
 215         return NULL;
 216 }
 217
 218 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
 219 {
 220         return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
 221                              0, t);
 222 }
 223 EXPORT_SYMBOL(xfrm6_rcv_tnl);
 224
 225 int xfrm6_rcv(struct sk_buff *skb)
 226 {
 227         return xfrm6_rcv_tnl(skb, NULL);
 228 }
 229 EXPORT_SYMBOL(xfrm6_rcv);
 230 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
 231                      xfrm_address_t *saddr, u8 proto)
 232 {
 233         struct net *net = dev_net(skb->dev);
 234         struct xfrm_state *x = NULL;
 235         struct sec_path *sp;
 236         int i = 0;
 237
 238         sp = secpath_set(skb);
 239         if (!sp) {
 240                 XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
 241                 goto drop;
 242         }
 243
 244         if (1 + sp->len == XFRM_MAX_DEPTH) {
 245                 XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
 246                 goto drop;
 247         }
 248
 249         for (i = 0; i < 3; i++) {
 250                 xfrm_address_t *dst, *src;
 251
 252                 switch (i) {
 253                 case 0:
 254                         dst = daddr;
 255                         src = saddr;
 256                         break;
 257                 case 1:
 258                         /* lookup state with wild-card source address */
 259                         dst = daddr;
 260                         src = (xfrm_address_t *)&in6addr_any;
 261                         break;
 262                 default:
 263                         /* lookup state with wild-card addresses */
 264                         dst = (xfrm_address_t *)&in6addr_any;
 265                         src = (xfrm_address_t *)&in6addr_any;
 266                         break;
 267                 }
 268
 269                 x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
 270                 if (!x)
 271                         continue;
 272
 273                 if (unlikely(x->dir && x->dir != XFRM_SA_DIR_IN)) {
 274                         XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEDIRERROR);
 275                         xfrm_state_put(x);
 276                         x = NULL;
 277                         continue;
 278                 }
 279
 280                 spin_lock(&x->lock);
 281
 282                 if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
 283                     likely(x->km.state == XFRM_STATE_VALID) &&
 284                     !xfrm_state_check_expire(x)) {
 285                         spin_unlock(&x->lock);
 286                         if (x->type->input(x, skb) > 0) {
 287                                 /* found a valid state */
 288                                 break;
 289                         }
 290                 } else
 291                         spin_unlock(&x->lock);
 292
 293                 xfrm_state_put(x);
 294                 x = NULL;
 295         }
 296
 297         if (!x) {
 298                 XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
 299                 xfrm_audit_state_notfound_simple(skb, AF_INET6);
 300                 goto drop;
 301         }
 302
 303         sp->xvec[sp->len++] = x;
 304
 305         spin_lock(&x->lock);
 306
 307         x->curlft.bytes += skb->len;
 308         x->curlft.packets++;
 309
 310         spin_unlock(&x->lock);
 311
 312         return 1;
 313
 314 drop:
 315         return -1;
 316 }
 317 EXPORT_SYMBOL(xfrm6_input_addr);