| /* |
| * xfrm4_input.c |
| * |
| * Changes: |
| * YOSHIFUJI Hideaki @USAGI |
| * Split up af-specific portion |
| * Derek Atkins <derek@ihtfp.com> |
| * Add Encapsulation support |
| * |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <linux/string.h> |
| #include <linux/netfilter.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <net/ip.h> |
| #include <net/xfrm.h> |
| |
| int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb) |
| { |
| return xfrm4_extract_header(skb); |
| } |
| |
| static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb) |
| { |
| if (skb_dst(skb) == NULL) { |
| const struct iphdr *iph = ip_hdr(skb); |
| |
| if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, |
| skb->dev)) |
| goto drop; |
| } |
| return dst_input(skb); |
| drop: |
| kfree_skb(skb); |
| return NET_RX_DROP; |
| } |
| |
| int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi, |
| int encap_type) |
| { |
| XFRM_SPI_SKB_CB(skb)->family = AF_INET; |
| XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr); |
| return xfrm_input(skb, nexthdr, spi, encap_type); |
| } |
| EXPORT_SYMBOL(xfrm4_rcv_encap); |
| |
| int xfrm4_transport_finish(struct sk_buff *skb, int async) |
| { |
| struct iphdr *iph = ip_hdr(skb); |
| |
| iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol; |
| |
| #ifndef CONFIG_NETFILTER |
| if (!async) |
| return -iph->protocol; |
| #endif |
| |
| __skb_push(skb, skb->data - skb_network_header(skb)); |
| iph->tot_len = htons(skb->len); |
| ip_send_check(iph); |
| |
| NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, |
| xfrm4_rcv_encap_finish); |
| return 0; |
| } |
| |
| /* If it's a keepalive packet, then just eat it. |
| * If it's an encapsulated packet, then pass it to the |
| * IPsec xfrm input. |
| * Returns 0 if skb passed to xfrm or was dropped. |
| * Returns >0 if skb should be passed to UDP. |
| * Returns <0 if skb should be resubmitted (-ret is protocol) |
| */ |
| int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb) |
| { |
| struct udp_sock *up = udp_sk(sk); |
| struct udphdr *uh; |
| struct iphdr *iph; |
| int iphlen, len; |
| |
| __u8 *udpdata; |
| __be32 *udpdata32; |
| __u16 encap_type = up->encap_type; |
| |
| /* if this is not encapsulated socket, then just return now */ |
| if (!encap_type) |
| return 1; |
| |
| /* If this is a paged skb, make sure we pull up |
| * whatever data we need to look at. */ |
| len = skb->len - sizeof(struct udphdr); |
| if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8))) |
| return 1; |
| |
| /* Now we can get the pointers */ |
| uh = udp_hdr(skb); |
| udpdata = (__u8 *)uh + sizeof(struct udphdr); |
| udpdata32 = (__be32 *)udpdata; |
| |
| switch (encap_type) { |
| default: |
| case UDP_ENCAP_ESPINUDP: |
| /* Check if this is a keepalive packet. If so, eat it. */ |
| if (len == 1 && udpdata[0] == 0xff) { |
| goto drop; |
| } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) { |
| /* ESP Packet without Non-ESP header */ |
| len = sizeof(struct udphdr); |
| } else |
| /* Must be an IKE packet.. pass it through */ |
| return 1; |
| break; |
| case UDP_ENCAP_ESPINUDP_NON_IKE: |
| /* Check if this is a keepalive packet. If so, eat it. */ |
| if (len == 1 && udpdata[0] == 0xff) { |
| goto drop; |
| } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) && |
| udpdata32[0] == 0 && udpdata32[1] == 0) { |
| |
| /* ESP Packet with Non-IKE marker */ |
| len = sizeof(struct udphdr) + 2 * sizeof(u32); |
| } else |
| /* Must be an IKE packet.. pass it through */ |
| return 1; |
| break; |
| } |
| |
| /* At this point we are sure that this is an ESPinUDP packet, |
| * so we need to remove 'len' bytes from the packet (the UDP |
| * header and optional ESP marker bytes) and then modify the |
| * protocol to ESP, and then call into the transform receiver. |
| */ |
| if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
| goto drop; |
| |
| /* Now we can update and verify the packet length... */ |
| iph = ip_hdr(skb); |
| iphlen = iph->ihl << 2; |
| iph->tot_len = htons(ntohs(iph->tot_len) - len); |
| if (skb->len < iphlen + len) { |
| /* packet is too small!?! */ |
| goto drop; |
| } |
| |
| /* pull the data buffer up to the ESP header and set the |
| * transport header to point to ESP. Keep UDP on the stack |
| * for later. |
| */ |
| __skb_pull(skb, len); |
| skb_reset_transport_header(skb); |
| |
| /* process ESP */ |
| return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); |
| |
| drop: |
| kfree_skb(skb); |
| return 0; |
| } |
| |
| int xfrm4_rcv(struct sk_buff *skb) |
| { |
| return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0); |
| } |
| |
| EXPORT_SYMBOL(xfrm4_rcv); |