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/slab.h> 13 #include <linux/module.h> 14 #include <linux/string.h> 15 #include <linux/netfilter.h> 16 #include <linux/netfilter_ipv4.h> 17 #include <net/ip.h> 18 #include <net/xfrm.h> 19 20 int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb) 21 { 22 return xfrm4_extract_header(skb); 23 } 24 25 static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk, 26 struct sk_buff *skb) 27 { 28 if (!skb_dst(skb)) { 29 const struct iphdr *iph = ip_hdr(skb); 30 31 if (ip_route_input_noref(skb, iph->daddr, iph->saddr, 32 iph->tos, skb->dev)) 33 goto drop; 34 } 35 return dst_input(skb); 36 drop: 37 kfree_skb(skb); 38 return NET_RX_DROP; 39 } 40 41 int xfrm4_transport_finish(struct sk_buff *skb, int async) 42 { 43 struct xfrm_offload *xo = xfrm_offload(skb); 44 struct iphdr *iph = ip_hdr(skb); 45 46 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; 47 48 #ifndef CONFIG_NETFILTER 49 if (!async) 50 return -iph->protocol; 51 #endif 52 53 __skb_push(skb, skb->data - skb_network_header(skb)); 54 iph->tot_len = htons(skb->len); 55 ip_send_check(iph); 56 57 if (xo && (xo->flags & XFRM_GRO)) { 58 skb_mac_header_rebuild(skb); 59 return 0; 60 } 61 62 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, 63 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 64 xfrm4_rcv_encap_finish); 65 return 0; 66 } 67 68 /* If it's a keepalive packet, then just eat it. 69 * If it's an encapsulated packet, then pass it to the 70 * IPsec xfrm input. 71 * Returns 0 if skb passed to xfrm or was dropped. 72 * Returns >0 if skb should be passed to UDP. 73 * Returns <0 if skb should be resubmitted (-ret is protocol) 74 */ 75 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) 76 { 77 struct udp_sock *up = udp_sk(sk); 78 struct udphdr *uh; 79 struct iphdr *iph; 80 int iphlen, len; 81 82 __u8 *udpdata; 83 __be32 *udpdata32; 84 __u16 encap_type = up->encap_type; 85 86 /* if this is not encapsulated socket, then just return now */ 87 if (!encap_type) 88 return 1; 89 90 /* If this is a paged skb, make sure we pull up 91 * whatever data we need to look at. */ 92 len = skb->len - sizeof(struct udphdr); 93 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8))) 94 return 1; 95 96 /* Now we can get the pointers */ 97 uh = udp_hdr(skb); 98 udpdata = (__u8 *)uh + sizeof(struct udphdr); 99 udpdata32 = (__be32 *)udpdata; 100 101 switch (encap_type) { 102 default: 103 case UDP_ENCAP_ESPINUDP: 104 /* Check if this is a keepalive packet. If so, eat it. */ 105 if (len == 1 && udpdata[0] == 0xff) { 106 goto drop; 107 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) { 108 /* ESP Packet without Non-ESP header */ 109 len = sizeof(struct udphdr); 110 } else 111 /* Must be an IKE packet.. pass it through */ 112 return 1; 113 break; 114 case UDP_ENCAP_ESPINUDP_NON_IKE: 115 /* Check if this is a keepalive packet. If so, eat it. */ 116 if (len == 1 && udpdata[0] == 0xff) { 117 goto drop; 118 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) && 119 udpdata32[0] == 0 && udpdata32[1] == 0) { 120 121 /* ESP Packet with Non-IKE marker */ 122 len = sizeof(struct udphdr) + 2 * sizeof(u32); 123 } else 124 /* Must be an IKE packet.. pass it through */ 125 return 1; 126 break; 127 } 128 129 /* At this point we are sure that this is an ESPinUDP packet, 130 * so we need to remove 'len' bytes from the packet (the UDP 131 * header and optional ESP marker bytes) and then modify the 132 * protocol to ESP, and then call into the transform receiver. 133 */ 134 if (skb_unclone(skb, GFP_ATOMIC)) 135 goto drop; 136 137 /* Now we can update and verify the packet length... */ 138 iph = ip_hdr(skb); 139 iphlen = iph->ihl << 2; 140 iph->tot_len = htons(ntohs(iph->tot_len) - len); 141 if (skb->len < iphlen + len) { 142 /* packet is too small!?! */ 143 goto drop; 144 } 145 146 /* pull the data buffer up to the ESP header and set the 147 * transport header to point to ESP. Keep UDP on the stack 148 * for later. 149 */ 150 __skb_pull(skb, len); 151 skb_reset_transport_header(skb); 152 153 /* process ESP */ 154 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); 155 156 drop: 157 kfree_skb(skb); 158 return 0; 159 } 160 161 int xfrm4_rcv(struct sk_buff *skb) 162 { 163 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); 164 } 165 EXPORT_SYMBOL(xfrm4_rcv); 166