/* * xfrm4_input.c * * Changes: * YOSHIFUJI Hideaki @USAGI * Split up af-specific portion * Derek Atkins <derek@ihtfp.com> * Add Encapsulation support * */ #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 == 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(PF_INET, 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; int ret; __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 */ ret = xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type); return ret; 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);