1 /* 2 * xfrm4_input.c 3 * 4 * Changes: 5 * YOSHIFUJI Hideaki @USAGI 6 * Split up af-specific portion 7 * Derek Atkins <derek@ihtfp.com> 8 * Add Encapsulation support 9 * 10 */ 11 12 #include <linux/module.h> 13 #include <linux/string.h> 14 #include <linux/netfilter.h> 15 #include <linux/netfilter_ipv4.h> 16 #include <net/ip.h> 17 #include <net/xfrm.h> 18 19 #ifdef CONFIG_NETFILTER 20 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb) 21 { 22 if (skb->dst == NULL) { 23 const struct iphdr *iph = ip_hdr(skb); 24 25 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, 26 skb->dev)) 27 goto drop; 28 } 29 return dst_input(skb); 30 drop: 31 kfree_skb(skb); 32 return NET_RX_DROP; 33 } 34 #endif 35 36 int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi, 37 int encap_type) 38 { 39 int err; 40 __be32 seq; 41 struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH]; 42 struct xfrm_state *x; 43 int xfrm_nr = 0; 44 int decaps = 0; 45 unsigned int nhoff = offsetof(struct iphdr, protocol); 46 47 seq = 0; 48 if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0) 49 goto drop; 50 51 do { 52 const struct iphdr *iph = ip_hdr(skb); 53 54 if (xfrm_nr == XFRM_MAX_DEPTH) 55 goto drop; 56 57 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, 58 nexthdr, AF_INET); 59 if (x == NULL) 60 goto drop; 61 62 spin_lock(&x->lock); 63 if (unlikely(x->km.state != XFRM_STATE_VALID)) 64 goto drop_unlock; 65 66 if ((x->encap ? x->encap->encap_type : 0) != encap_type) 67 goto drop_unlock; 68 69 if (x->props.replay_window && xfrm_replay_check(x, seq)) 70 goto drop_unlock; 71 72 if (xfrm_state_check_expire(x)) 73 goto drop_unlock; 74 75 nexthdr = x->type->input(x, skb); 76 if (nexthdr <= 0) 77 goto drop_unlock; 78 79 skb_network_header(skb)[nhoff] = nexthdr; 80 81 /* only the first xfrm gets the encap type */ 82 encap_type = 0; 83 84 if (x->props.replay_window) 85 xfrm_replay_advance(x, seq); 86 87 x->curlft.bytes += skb->len; 88 x->curlft.packets++; 89 90 spin_unlock(&x->lock); 91 92 xfrm_vec[xfrm_nr++] = x; 93 94 if (x->outer_mode->input(x, skb)) 95 goto drop; 96 97 if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) { 98 decaps = 1; 99 break; 100 } 101 102 err = xfrm_parse_spi(skb, nexthdr, &spi, &seq); 103 if (err < 0) 104 goto drop; 105 } while (!err); 106 107 /* Allocate new secpath or COW existing one. */ 108 109 if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) { 110 struct sec_path *sp; 111 sp = secpath_dup(skb->sp); 112 if (!sp) 113 goto drop; 114 if (skb->sp) 115 secpath_put(skb->sp); 116 skb->sp = sp; 117 } 118 if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH) 119 goto drop; 120 121 memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec, 122 xfrm_nr * sizeof(xfrm_vec[0])); 123 skb->sp->len += xfrm_nr; 124 125 nf_reset(skb); 126 127 if (decaps) { 128 dst_release(skb->dst); 129 skb->dst = NULL; 130 netif_rx(skb); 131 return 0; 132 } else { 133 #ifdef CONFIG_NETFILTER 134 __skb_push(skb, skb->data - skb_network_header(skb)); 135 ip_hdr(skb)->tot_len = htons(skb->len); 136 ip_send_check(ip_hdr(skb)); 137 138 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL, 139 xfrm4_rcv_encap_finish); 140 return 0; 141 #else 142 return -ip_hdr(skb)->protocol; 143 #endif 144 } 145 146 drop_unlock: 147 spin_unlock(&x->lock); 148 xfrm_state_put(x); 149 drop: 150 while (--xfrm_nr >= 0) 151 xfrm_state_put(xfrm_vec[xfrm_nr]); 152 153 kfree_skb(skb); 154 return 0; 155 } 156 EXPORT_SYMBOL(xfrm4_rcv_encap); 157 158 /* If it's a keepalive packet, then just eat it. 159 * If it's an encapsulated packet, then pass it to the 160 * IPsec xfrm input. 161 * Returns 0 if skb passed to xfrm or was dropped. 162 * Returns >0 if skb should be passed to UDP. 163 * Returns <0 if skb should be resubmitted (-ret is protocol) 164 */ 165 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) 166 { 167 struct udp_sock *up = udp_sk(sk); 168 struct udphdr *uh; 169 struct iphdr *iph; 170 int iphlen, len; 171 int ret; 172 173 __u8 *udpdata; 174 __be32 *udpdata32; 175 __u16 encap_type = up->encap_type; 176 177 /* if this is not encapsulated socket, then just return now */ 178 if (!encap_type) 179 return 1; 180 181 /* If this is a paged skb, make sure we pull up 182 * whatever data we need to look at. */ 183 len = skb->len - sizeof(struct udphdr); 184 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8))) 185 return 1; 186 187 /* Now we can get the pointers */ 188 uh = udp_hdr(skb); 189 udpdata = (__u8 *)uh + sizeof(struct udphdr); 190 udpdata32 = (__be32 *)udpdata; 191 192 switch (encap_type) { 193 default: 194 case UDP_ENCAP_ESPINUDP: 195 /* Check if this is a keepalive packet. If so, eat it. */ 196 if (len == 1 && udpdata[0] == 0xff) { 197 goto drop; 198 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) { 199 /* ESP Packet without Non-ESP header */ 200 len = sizeof(struct udphdr); 201 } else 202 /* Must be an IKE packet.. pass it through */ 203 return 1; 204 break; 205 case UDP_ENCAP_ESPINUDP_NON_IKE: 206 /* Check if this is a keepalive packet. If so, eat it. */ 207 if (len == 1 && udpdata[0] == 0xff) { 208 goto drop; 209 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) && 210 udpdata32[0] == 0 && udpdata32[1] == 0) { 211 212 /* ESP Packet with Non-IKE marker */ 213 len = sizeof(struct udphdr) + 2 * sizeof(u32); 214 } else 215 /* Must be an IKE packet.. pass it through */ 216 return 1; 217 break; 218 } 219 220 /* At this point we are sure that this is an ESPinUDP packet, 221 * so we need to remove 'len' bytes from the packet (the UDP 222 * header and optional ESP marker bytes) and then modify the 223 * protocol to ESP, and then call into the transform receiver. 224 */ 225 if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 226 goto drop; 227 228 /* Now we can update and verify the packet length... */ 229 iph = ip_hdr(skb); 230 iphlen = iph->ihl << 2; 231 iph->tot_len = htons(ntohs(iph->tot_len) - len); 232 if (skb->len < iphlen + len) { 233 /* packet is too small!?! */ 234 goto drop; 235 } 236 237 /* pull the data buffer up to the ESP header and set the 238 * transport header to point to ESP. Keep UDP on the stack 239 * for later. 240 */ 241 __skb_pull(skb, len); 242 skb_reset_transport_header(skb); 243 244 /* process ESP */ 245 ret = xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); 246 return ret; 247 248 drop: 249 kfree_skb(skb); 250 return 0; 251 } 252 253 int xfrm4_rcv(struct sk_buff *skb) 254 { 255 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); 256 } 257 258 EXPORT_SYMBOL(xfrm4_rcv); 259