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 ip4h_dscp(iph), 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 struct net_device *dev = skb->dev; 54 55 iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; 56 57 #ifndef CONFIG_NETFILTER 58 if (!async) 59 return -iph->protocol; 60 #endif 61 62 __skb_push(skb, -skb_network_offset(skb)); 63 iph->tot_len = htons(skb->len); 64 ip_send_check(iph); 65 66 if (xo && (xo->flags & XFRM_GRO)) { 67 /* The full l2 header needs to be preserved so that re-injecting the packet at l2 68 * works correctly in the presence of vlan tags. 69 */ 70 skb_mac_header_rebuild_full(skb, xo->orig_mac_len); 71 skb_reset_network_header(skb); 72 skb_reset_transport_header(skb); 73 return 0; 74 } 75 76 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, 77 dev_net(dev), NULL, skb, dev, NULL, 78 xfrm4_rcv_encap_finish); 79 return 0; 80 } 81 82 static int __xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb, bool pull) 83 { 84 struct udp_sock *up = udp_sk(sk); 85 struct udphdr *uh; 86 struct iphdr *iph; 87 int iphlen, len; 88 __u8 *udpdata; 89 __be32 *udpdata32; 90 u16 encap_type; 91 92 encap_type = READ_ONCE(up->encap_type); 93 /* if this is not encapsulated socket, then just return now */ 94 if (!encap_type) 95 return 1; 96 97 /* If this is a paged skb, make sure we pull up 98 * whatever data we need to look at. */ 99 len = skb->len - sizeof(struct udphdr); 100 if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8))) 101 return 1; 102 103 /* Now we can get the pointers */ 104 uh = udp_hdr(skb); 105 udpdata = (__u8 *)uh + sizeof(struct udphdr); 106 udpdata32 = (__be32 *)udpdata; 107 108 switch (encap_type) { 109 default: 110 case UDP_ENCAP_ESPINUDP: 111 /* Check if this is a keepalive packet. If so, eat it. */ 112 if (len == 1 && udpdata[0] == 0xff) { 113 return -EINVAL; 114 } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) { 115 /* ESP Packet without Non-ESP header */ 116 len = sizeof(struct udphdr); 117 } else 118 /* Must be an IKE packet.. pass it through */ 119 return 1; 120 break; 121 } 122 123 /* At this point we are sure that this is an ESPinUDP packet, 124 * so we need to remove 'len' bytes from the packet (the UDP 125 * header and optional ESP marker bytes) and then modify the 126 * protocol to ESP, and then call into the transform receiver. 127 */ 128 if (skb_unclone(skb, GFP_ATOMIC)) 129 return -EINVAL; 130 131 /* Now we can update and verify the packet length... */ 132 iph = ip_hdr(skb); 133 iphlen = iph->ihl << 2; 134 iph->tot_len = htons(ntohs(iph->tot_len) - len); 135 if (skb->len < iphlen + len) { 136 /* packet is too small!?! */ 137 return -EINVAL; 138 } 139 140 /* pull the data buffer up to the ESP header and set the 141 * transport header to point to ESP. Keep UDP on the stack 142 * for later. 143 */ 144 if (pull) { 145 __skb_pull(skb, len); 146 skb_reset_transport_header(skb); 147 } else { 148 skb_set_transport_header(skb, len); 149 } 150 151 /* process ESP */ 152 return 0; 153 } 154 155 /* If it's a keepalive packet, then just eat it. 156 * If it's an encapsulated packet, then pass it to the 157 * IPsec xfrm input. 158 * Returns 0 if skb passed to xfrm or was dropped. 159 * Returns >0 if skb should be passed to UDP. 160 * Returns <0 if skb should be resubmitted (-ret is protocol) 161 */ 162 int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) 163 { 164 int ret; 165 166 ret = __xfrm4_udp_encap_rcv(sk, skb, true); 167 if (!ret) 168 return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, 169 udp_sk(sk)->encap_type); 170 171 if (ret < 0) { 172 kfree_skb(skb); 173 return 0; 174 } 175 176 return ret; 177 } 178 EXPORT_SYMBOL(xfrm4_udp_encap_rcv); 179 180 struct sk_buff *xfrm4_gro_udp_encap_rcv(struct sock *sk, struct list_head *head, 181 struct sk_buff *skb) 182 { 183 int offset = skb_gro_offset(skb); 184 const struct net_offload *ops; 185 struct sk_buff *pp = NULL; 186 int len, dlen; 187 __u8 *udpdata; 188 __be32 *udpdata32; 189 190 len = skb->len - offset; 191 dlen = offset + min(len, 8); 192 udpdata = skb_gro_header(skb, dlen, offset); 193 udpdata32 = (__be32 *)udpdata; 194 if (unlikely(!udpdata)) 195 return NULL; 196 197 rcu_read_lock(); 198 ops = rcu_dereference(inet_offloads[IPPROTO_ESP]); 199 if (!ops || !ops->callbacks.gro_receive) 200 goto out; 201 202 /* check if it is a keepalive or IKE packet */ 203 if (len <= sizeof(struct ip_esp_hdr) || udpdata32[0] == 0) 204 goto out; 205 206 /* set the transport header to ESP */ 207 skb_set_transport_header(skb, offset); 208 209 NAPI_GRO_CB(skb)->proto = IPPROTO_UDP; 210 211 pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); 212 rcu_read_unlock(); 213 214 return pp; 215 216 out: 217 rcu_read_unlock(); 218 NAPI_GRO_CB(skb)->same_flow = 0; 219 NAPI_GRO_CB(skb)->flush = 1; 220 221 return NULL; 222 } 223 EXPORT_SYMBOL(xfrm4_gro_udp_encap_rcv); 224 225 int xfrm4_rcv(struct sk_buff *skb) 226 { 227 return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); 228 } 229 EXPORT_SYMBOL(xfrm4_rcv); 230