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Linux/net/ipv6/xfrm6_input.c

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  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 
 20 int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi,
 21                   struct ip6_tnl *t)
 22 {
 23         XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = t;
 24         XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
 25         XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
 26         return xfrm_input(skb, nexthdr, spi, 0);
 27 }
 28 EXPORT_SYMBOL(xfrm6_rcv_spi);
 29 
 30 static int xfrm6_transport_finish2(struct net *net, struct sock *sk,
 31                                    struct sk_buff *skb)
 32 {
 33         if (xfrm_trans_queue(skb, ip6_rcv_finish)) {
 34                 kfree_skb(skb);
 35                 return NET_RX_DROP;
 36         }
 37 
 38         return 0;
 39 }
 40 
 41 int xfrm6_transport_finish(struct sk_buff *skb, int async)
 42 {
 43         struct xfrm_offload *xo = xfrm_offload(skb);
 44         int nhlen = skb->data - skb_network_header(skb);
 45 
 46         skb_network_header(skb)[IP6CB(skb)->nhoff] =
 47                 XFRM_MODE_SKB_CB(skb)->protocol;
 48 
 49 #ifndef CONFIG_NETFILTER
 50         if (!async)
 51                 return 1;
 52 #endif
 53 
 54         __skb_push(skb, nhlen);
 55         ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 56         skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
 57 
 58         if (xo && (xo->flags & XFRM_GRO)) {
 59                 skb_mac_header_rebuild(skb);
 60                 skb_reset_transport_header(skb);
 61                 return 0;
 62         }
 63 
 64         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
 65                 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 66                 xfrm6_transport_finish2);
 67         return 0;
 68 }
 69 
 70 /* If it's a keepalive packet, then just eat it.
 71  * If it's an encapsulated packet, then pass it to the
 72  * IPsec xfrm input.
 73  * Returns 0 if skb passed to xfrm or was dropped.
 74  * Returns >0 if skb should be passed to UDP.
 75  * Returns <0 if skb should be resubmitted (-ret is protocol)
 76  */
 77 int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
 78 {
 79         struct udp_sock *up = udp_sk(sk);
 80         struct udphdr *uh;
 81         struct ipv6hdr *ip6h;
 82         int len;
 83         int ip6hlen = sizeof(struct ipv6hdr);
 84 
 85         __u8 *udpdata;
 86         __be32 *udpdata32;
 87         __u16 encap_type = up->encap_type;
 88 
 89         /* if this is not encapsulated socket, then just return now */
 90         if (!encap_type)
 91                 return 1;
 92 
 93         /* If this is a paged skb, make sure we pull up
 94          * whatever data we need to look at. */
 95         len = skb->len - sizeof(struct udphdr);
 96         if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
 97                 return 1;
 98 
 99         /* Now we can get the pointers */
100         uh = udp_hdr(skb);
101         udpdata = (__u8 *)uh + sizeof(struct udphdr);
102         udpdata32 = (__be32 *)udpdata;
103 
104         switch (encap_type) {
105         default:
106         case UDP_ENCAP_ESPINUDP:
107                 /* Check if this is a keepalive packet.  If so, eat it. */
108                 if (len == 1 && udpdata[0] == 0xff) {
109                         goto drop;
110                 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
111                         /* ESP Packet without Non-ESP header */
112                         len = sizeof(struct udphdr);
113                 } else
114                         /* Must be an IKE packet.. pass it through */
115                         return 1;
116                 break;
117         case UDP_ENCAP_ESPINUDP_NON_IKE:
118                 /* Check if this is a keepalive packet.  If so, eat it. */
119                 if (len == 1 && udpdata[0] == 0xff) {
120                         goto drop;
121                 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
122                            udpdata32[0] == 0 && udpdata32[1] == 0) {
123 
124                         /* ESP Packet with Non-IKE marker */
125                         len = sizeof(struct udphdr) + 2 * sizeof(u32);
126                 } else
127                         /* Must be an IKE packet.. pass it through */
128                         return 1;
129                 break;
130         }
131 
132         /* At this point we are sure that this is an ESPinUDP packet,
133          * so we need to remove 'len' bytes from the packet (the UDP
134          * header and optional ESP marker bytes) and then modify the
135          * protocol to ESP, and then call into the transform receiver.
136          */
137         if (skb_unclone(skb, GFP_ATOMIC))
138                 goto drop;
139 
140         /* Now we can update and verify the packet length... */
141         ip6h = ipv6_hdr(skb);
142         ip6h->payload_len = htons(ntohs(ip6h->payload_len) - len);
143         if (skb->len < ip6hlen + len) {
144                 /* packet is too small!?! */
145                 goto drop;
146         }
147 
148         /* pull the data buffer up to the ESP header and set the
149          * transport header to point to ESP.  Keep UDP on the stack
150          * for later.
151          */
152         __skb_pull(skb, len);
153         skb_reset_transport_header(skb);
154 
155         /* process ESP */
156         return xfrm6_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
157 
158 drop:
159         kfree_skb(skb);
160         return 0;
161 }
162 
163 int xfrm6_rcv_tnl(struct sk_buff *skb, struct ip6_tnl *t)
164 {
165         return xfrm6_rcv_spi(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
166                              0, t);
167 }
168 EXPORT_SYMBOL(xfrm6_rcv_tnl);
169 
170 int xfrm6_rcv(struct sk_buff *skb)
171 {
172         return xfrm6_rcv_tnl(skb, NULL);
173 }
174 EXPORT_SYMBOL(xfrm6_rcv);
175 int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr,
176                      xfrm_address_t *saddr, u8 proto)
177 {
178         struct net *net = dev_net(skb->dev);
179         struct xfrm_state *x = NULL;
180         struct sec_path *sp;
181         int i = 0;
182 
183         sp = secpath_set(skb);
184         if (!sp) {
185                 XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
186                 goto drop;
187         }
188 
189         if (1 + sp->len == XFRM_MAX_DEPTH) {
190                 XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
191                 goto drop;
192         }
193 
194         for (i = 0; i < 3; i++) {
195                 xfrm_address_t *dst, *src;
196 
197                 switch (i) {
198                 case 0:
199                         dst = daddr;
200                         src = saddr;
201                         break;
202                 case 1:
203                         /* lookup state with wild-card source address */
204                         dst = daddr;
205                         src = (xfrm_address_t *)&in6addr_any;
206                         break;
207                 default:
208                         /* lookup state with wild-card addresses */
209                         dst = (xfrm_address_t *)&in6addr_any;
210                         src = (xfrm_address_t *)&in6addr_any;
211                         break;
212                 }
213 
214                 x = xfrm_state_lookup_byaddr(net, skb->mark, dst, src, proto, AF_INET6);
215                 if (!x)
216                         continue;
217 
218                 spin_lock(&x->lock);
219 
220                 if ((!i || (x->props.flags & XFRM_STATE_WILDRECV)) &&
221                     likely(x->km.state == XFRM_STATE_VALID) &&
222                     !xfrm_state_check_expire(x)) {
223                         spin_unlock(&x->lock);
224                         if (x->type->input(x, skb) > 0) {
225                                 /* found a valid state */
226                                 break;
227                         }
228                 } else
229                         spin_unlock(&x->lock);
230 
231                 xfrm_state_put(x);
232                 x = NULL;
233         }
234 
235         if (!x) {
236                 XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
237                 xfrm_audit_state_notfound_simple(skb, AF_INET6);
238                 goto drop;
239         }
240 
241         sp->xvec[sp->len++] = x;
242 
243         spin_lock(&x->lock);
244 
245         x->curlft.bytes += skb->len;
246         x->curlft.packets++;
247 
248         spin_unlock(&x->lock);
249 
250         return 1;
251 
252 drop:
253         return -1;
254 }
255 EXPORT_SYMBOL(xfrm6_input_addr);
256 

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