LXR linux/net/ipv4/xfrm4

   1/*
   2 * xfrm4_input.c
   3 *
   4 * Changes:
   5 *      YOSHIFUJI Hideaki @USAGI
   6 *              Split up af-specific portion
   7 *      Derek Atkins <derek@ihtfp.com>
   8 *              Add Encapsulation support
   9 *
  10 */
  11
  12#include <linux/slab.h>
  13#include <linux/module.h>
  14#include <linux/string.h>
  15#include <linux/netfilter.h>
  16#include <linux/netfilter_ipv4.h>
  17#include <net/ip.h>
  18#include <net/xfrm.h>
  19
  20int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
  21{
  22        return xfrm4_extract_header(skb);
  23}
  24
  25static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk,
  26                                         struct sk_buff *skb)
  27{
  28        if (!skb_dst(skb)) {
  29                const struct iphdr *iph = ip_hdr(skb);
  30
  31                if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
  32                                         iph->tos, skb->dev))
  33                        goto drop;
  34        }
  35        return dst_input(skb);
  36drop:
  37        kfree_skb(skb);
  38        return NET_RX_DROP;
  39}
  40
  41int xfrm4_transport_finish(struct sk_buff *skb, int async)
  42{
  43        struct xfrm_offload *xo = xfrm_offload(skb);
  44        struct iphdr *iph = ip_hdr(skb);
  45
  46        iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
  47
  48#ifndef CONFIG_NETFILTER
  49        if (!async)
  50                return -iph->protocol;
  51#endif
  52
  53        __skb_push(skb, skb->data - skb_network_header(skb));
  54        iph->tot_len = htons(skb->len);
  55        ip_send_check(iph);
  56
  57        if (xo && (xo->flags & XFRM_GRO)) {
  58                skb_mac_header_rebuild(skb);
  59                return 0;
  60        }
  61
  62        NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
  63                dev_net(skb->dev), NULL, skb, skb->dev, NULL,
  64                xfrm4_rcv_encap_finish);
  65        return 0;
  66}
  67
  68/* If it's a keepalive packet, then just eat it.
  69 * If it's an encapsulated packet, then pass it to the
  70 * IPsec xfrm input.
  71 * Returns 0 if skb passed to xfrm or was dropped.
  72 * Returns >0 if skb should be passed to UDP.
  73 * Returns <0 if skb should be resubmitted (-ret is protocol)
  74 */
  75int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
  76{
  77        struct udp_sock *up = udp_sk(sk);
  78        struct udphdr *uh;
  79        struct iphdr *iph;
  80        int iphlen, len;
  81
  82        __u8 *udpdata;
  83        __be32 *udpdata32;
  84        __u16 encap_type = up->encap_type;
  85
  86        /* if this is not encapsulated socket, then just return now */
  87        if (!encap_type)
  88                return 1;
  89
  90        /* If this is a paged skb, make sure we pull up
  91         * whatever data we need to look at. */
  92        len = skb->len - sizeof(struct udphdr);
  93        if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
  94                return 1;
  95
  96        /* Now we can get the pointers */
  97        uh = udp_hdr(skb);
  98        udpdata = (__u8 *)uh + sizeof(struct udphdr);
  99        udpdata32 = (__be32 *)udpdata;
 100
 101        switch (encap_type) {
 102        default:
 103        case UDP_ENCAP_ESPINUDP:
 104                /* Check if this is a keepalive packet.  If so, eat it. */
 105                if (len == 1 && udpdata[0] == 0xff) {
 106                        goto drop;
 107                } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
 108                        /* ESP Packet without Non-ESP header */
 109                        len = sizeof(struct udphdr);
 110                } else
 111                        /* Must be an IKE packet.. pass it through */
 112                        return 1;
 113                break;
 114        case UDP_ENCAP_ESPINUDP_NON_IKE:
 115                /* Check if this is a keepalive packet.  If so, eat it. */
 116                if (len == 1 && udpdata[0] == 0xff) {
 117                        goto drop;
 118                } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
 119                           udpdata32[0] == 0 && udpdata32[1] == 0) {
 120
 121                        /* ESP Packet with Non-IKE marker */
 122                        len = sizeof(struct udphdr) + 2 * sizeof(u32);
 123                } else
 124                        /* Must be an IKE packet.. pass it through */
 125                        return 1;
 126                break;
 127        }
 128
 129        /* At this point we are sure that this is an ESPinUDP packet,
 130         * so we need to remove 'len' bytes from the packet (the UDP
 131         * header and optional ESP marker bytes) and then modify the
 132         * protocol to ESP, and then call into the transform receiver.
 133         */
 134        if (skb_unclone(skb, GFP_ATOMIC))
 135                goto drop;
 136
 137        /* Now we can update and verify the packet length... */
 138        iph = ip_hdr(skb);
 139        iphlen = iph->ihl << 2;
 140        iph->tot_len = htons(ntohs(iph->tot_len) - len);
 141        if (skb->len < iphlen + len) {
 142                /* packet is too small!?! */
 143                goto drop;
 144        }
 145
 146        /* pull the data buffer up to the ESP header and set the
 147         * transport header to point to ESP.  Keep UDP on the stack
 148         * for later.
 149         */
 150        __skb_pull(skb, len);
 151        skb_reset_transport_header(skb);
 152
 153        /* process ESP */
 154        return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
 155
 156drop:
 157        kfree_skb(skb);
 158        return 0;
 159}
 160
 161int xfrm4_rcv(struct sk_buff *skb)
 162{
 163        return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
 164}
 165EXPORT_SYMBOL(xfrm4_rcv);
 166