1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * xfrm4_input.c 4 * 5 * Changes: 6 * YOSHIFUJI Hideaki @USAGI 7 * Split up af-specific portion 8 * Derek Atkins <derek@ihtfp.com> 9 * Add Encapsulation support 10 * 11 */ 12 13 #include <linux/slab.h> 14 #include <linux/module.h> 15 #include <linux/string.h> 16 #include <linux/netfilter.h> 17 #include <linux/netfilter_ipv4.h> 18 #include <net/ip.h> 19 #include <net/xfrm.h> 20 21 int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb) 22 { 23 return xfrm4_extract_header(skb); 24 } 25 26 static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk, 27 struct sk_buff *skb) 28 { 29 return dst_input(skb); 30 } 31 32 static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk, 33 struct sk_buff *skb) 34 { 35 if (!skb_dst(skb)) { 36 const struct iphdr *iph = ip_hdr(skb); 37 38 if (ip_route_input_noref(skb, iph->daddr, iph->saddr, 39 iph->tos, skb->dev)) 40 goto drop; 41 } 42 43 if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2)) 44 goto drop; 45 46 return 0; 47 drop: 48 kfree_skb(skb); 49 return NET_RX_DROP; 50 } 51 52 int xfrm4_transport_finish(struct sk_buff *skb, int async) 53 { 54 struct xfrm_offload *xo = xfrm_offload(skb); 55 struct iphdr *iph = ip_hdr(skb); 56 57 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; 58 59 #ifndef CONFIG_NETFILTER 60 if (!async) 61 return -iph->protocol; 62 #endif 63 64 __skb_push(skb, skb->data - skb_network_header(skb)); 65 iph->tot_len = htons(skb->len); 66 ip_send_check(iph); 67 68 if (xo && (xo->flags & XFRM_GRO)) { 69 skb_mac_header_rebuild(skb); 70 skb_reset_transport_header(skb); 71 return 0; 72 } 73 74 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, 75 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 76 xfrm4_rcv_encap_finish); 77 return 0; 78 } 79 80 /* If it's a keepalive packet, then just eat it. 81 * If it's an encapsulated packet, then pass it to the 82 * IPsec xfrm input. 83 * Returns 0 if skb passed to xfrm or was dropped. 84 * Returns >0 if skb should be passed to UDP. 85 * Returns <0 if skb should be resubmitted (-ret is protocol) 86 */ 87 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) 88 { 89 struct udp_sock *up = udp_sk(sk); 90 struct udphdr *uh; 91 struct iphdr *iph; 92 int iphlen, len; 93 94 __u8 *udpdata; 95 __be32 *udpdata32; 96 __u16 encap_type = up->encap_type; 97 98 /* if this is not encapsulated socket, then just return now */ 99 if (!encap_type) 100 return 1; 101 102 /* If this is a paged skb, make sure we pull up 103 * whatever data we need to look at. */ 104 len = skb->len - sizeof(struct udphdr); 105 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8))) 106 return 1; 107 108 /* Now we can get the pointers */ 109 uh = udp_hdr(skb); 110 udpdata = (__u8 *)uh + sizeof(struct udphdr); 111 udpdata32 = (__be32 *)udpdata; 112 113 switch (encap_type) { 114 default: 115 case UDP_ENCAP_ESPINUDP: 116 /* Check if this is a keepalive packet. If so, eat it. */ 117 if (len == 1 && udpdata[0] == 0xff) { 118 goto drop; 119 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) { 120 /* ESP Packet without Non-ESP header */ 121 len = sizeof(struct udphdr); 122 } else 123 /* Must be an IKE packet.. pass it through */ 124 return 1; 125 break; 126 case UDP_ENCAP_ESPINUDP_NON_IKE: 127 /* Check if this is a keepalive packet. If so, eat it. */ 128 if (len == 1 && udpdata[0] == 0xff) { 129 goto drop; 130 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) && 131 udpdata32[0] == 0 && udpdata32[1] == 0) { 132 133 /* ESP Packet with Non-IKE marker */ 134 len = sizeof(struct udphdr) + 2 * sizeof(u32); 135 } else 136 /* Must be an IKE packet.. pass it through */ 137 return 1; 138 break; 139 } 140 141 /* At this point we are sure that this is an ESPinUDP packet, 142 * so we need to remove 'len' bytes from the packet (the UDP 143 * header and optional ESP marker bytes) and then modify the 144 * protocol to ESP, and then call into the transform receiver. 145 */ 146 if (skb_unclone(skb, GFP_ATOMIC)) 147 goto drop; 148 149 /* Now we can update and verify the packet length... */ 150 iph = ip_hdr(skb); 151 iphlen = iph->ihl << 2; 152 iph->tot_len = htons(ntohs(iph->tot_len) - len); 153 if (skb->len < iphlen + len) { 154 /* packet is too small!?! */ 155 goto drop; 156 } 157 158 /* pull the data buffer up to the ESP header and set the 159 * transport header to point to ESP. Keep UDP on the stack 160 * for later. 161 */ 162 __skb_pull(skb, len); 163 skb_reset_transport_header(skb); 164 165 /* process ESP */ 166 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); 167 168 drop: 169 kfree_skb(skb); 170 return 0; 171 } 172 173 int xfrm4_rcv(struct sk_buff *skb) 174 { 175 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); 176 } 177 EXPORT_SYMBOL(xfrm4_rcv); 178