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