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 #include <net/protocol.h> 21 #include <net/gro.h> 22 23 static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk, 24 struct sk_buff *skb) 25 { 26 return dst_input(skb); 27 } 28 29 static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk, 30 struct sk_buff *skb) 31 { 32 if (!skb_dst(skb)) { 33 const struct iphdr *iph = ip_hdr(skb); 34 35 if (ip_route_input_noref(skb, iph->daddr, iph->saddr, 36 iph->tos, skb->dev)) 37 goto drop; 38 } 39 40 if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2)) 41 goto drop; 42 43 return 0; 44 drop: 45 kfree_skb(skb); 46 return NET_RX_DROP; 47 } 48 49 int xfrm4_transport_finish(struct sk_buff *skb, int async) 50 { 51 struct xfrm_offload *xo = xfrm_offload(skb); 52 struct iphdr *iph = ip_hdr(skb); 53 54 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; 55 56 #ifndef CONFIG_NETFILTER 57 if (!async) 58 return -iph->protocol; 59 #endif 60 61 __skb_push(skb, -skb_network_offset(skb)); 62 iph->tot_len = htons(skb->len); 63 ip_send_check(iph); 64 65 if (xo && (xo->flags & XFRM_GRO)) { 66 skb_mac_header_rebuild(skb); 67 skb_reset_transport_header(skb); 68 return 0; 69 } 70 71 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, 72 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 73 xfrm4_rcv_encap_finish); 74 return 0; 75 } 76 77 static int __xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull) 78 { 79 struct udp_sock *up = udp_sk(sk); 80 struct udphdr *uh; 81 struct iphdr *iph; 82 int iphlen, len; 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 case UDP_ENCAP_ESPINUDP_NON_IKE: 117 /* Check if this is a keepalive packet. If so, eat it. */ 118 if (len == 1 && udpdata[0] == 0xff) { 119 return -EINVAL; 120 } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) && 121 udpdata32[0] == 0 && udpdata32[1] == 0) { 122 123 /* ESP Packet with Non-IKE marker */ 124 len = sizeof(struct udphdr) + 2 * sizeof(u32); 125 } else 126 /* Must be an IKE packet.. pass it through */ 127 return 1; 128 break; 129 } 130 131 /* At this point we are sure that this is an ESPinUDP packet, 132 * so we need to remove 'len' bytes from the packet (the UDP 133 * header and optional ESP marker bytes) and then modify the 134 * protocol to ESP, and then call into the transform receiver. 135 */ 136 if (skb_unclone(skb, GFP_ATOMIC)) 137 return -EINVAL; 138 139 /* Now we can update and verify the packet length... */ 140 iph = ip_hdr(skb); 141 iphlen = iph->ihl << 2; 142 iph->tot_len = htons(ntohs(iph->tot_len) - len); 143 if (skb->len < iphlen + len) { 144 /* packet is too small!?! */ 145 return -EINVAL; 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 if (pull) { 153 __skb_pull(skb, len); 154 skb_reset_transport_header(skb); 155 } else { 156 skb_set_transport_header(skb, len); 157 } 158 159 /* process ESP */ 160 return 0; 161 } 162 163 /* If it's a keepalive packet, then just eat it. 164 * If it's an encapsulated packet, then pass it to the 165 * IPsec xfrm input. 166 * Returns 0 if skb passed to xfrm or was dropped. 167 * Returns >0 if skb should be passed to UDP. 168 * Returns <0 if skb should be resubmitted (-ret is protocol) 169 */ 170 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) 171 { 172 int ret; 173 174 ret = __xfrm4_udp_encap_rcv(sk, skb, true); 175 if (!ret) 176 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, 177 udp_sk(sk)->encap_type); 178 179 if (ret < 0) { 180 kfree_skb(skb); 181 return 0; 182 } 183 184 return ret; 185 } 186 EXPORT_SYMBOL(xfrm4_udp_encap_rcv); 187 188 struct sk_buff *xfrm4_gro_udp_encap_rcv(struct sock *sk, struct list_head *head, 189 struct sk_buff *skb) 190 { 191 int offset = skb_gro_offset(skb); 192 const struct net_offload *ops; 193 struct sk_buff *pp = NULL; 194 int ret; 195 196 offset = offset - sizeof(struct udphdr); 197 198 if (!pskb_pull(skb, offset)) 199 return NULL; 200 201 rcu_read_lock(); 202 ops = rcu_dereference(inet_offloads[IPPROTO_ESP]); 203 if (!ops || !ops->callbacks.gro_receive) 204 goto out; 205 206 ret = __xfrm4_udp_encap_rcv(sk, skb, false); 207 if (ret) 208 goto out; 209 210 skb_push(skb, offset); 211 NAPI_GRO_CB(skb)->proto = IPPROTO_UDP; 212 213 pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); 214 rcu_read_unlock(); 215 216 return pp; 217 218 out: 219 rcu_read_unlock(); 220 skb_push(skb, offset); 221 NAPI_GRO_CB(skb)->same_flow = 0; 222 NAPI_GRO_CB(skb)->flush = 1; 223 224 return NULL; 225 } 226 EXPORT_SYMBOL(xfrm4_gro_udp_encap_rcv); 227 228 int xfrm4_rcv(struct sk_buff *skb) 229 { 230 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); 231 } 232 EXPORT_SYMBOL(xfrm4_rcv); 233