[UDP]: Cleanup UDP encapsulation code

This cleanup fell out after adding L2TP support where a new encap_rcv
funcptr was added to struct udp_sock. Have XFRM use the new encap_rcv
funcptr, which allows us to move the XFRM encap code from udp.c into
xfrm4_input.c.

Make xfrm4_rcv_encap() static since it is no longer called externally.

Signed-off-by: James Chapman <jchapman@katalix.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 132 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b9276f8bdac5..4ec4a25a8d0c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -920,108 +920,6 @@ int udp_disconnect(struct sock *sk, int flags)
         return 0;
 }
 
-/* return:
- *      1  if the UDP system should process it
- *      0  if we should drop this packet
- *      -1 if it should get processed by xfrm4_rcv_encap
- *      -2 if it should get processed by l2tp
- */
-static int 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 we're overly short, let UDP handle it */
-        len = skb->len - sizeof(struct udphdr);
-        if (len <= 0)
-                return 1;
-
-        /* 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. */
-        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) {
-                        return 0;
-                } 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) {
-                        return 0;
-                } 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;
-        case UDP_ENCAP_L2TPINUDP:
-                /* Let caller know to send this to l2tp */
-                return -2;
-        }
-
-#ifndef CONFIG_XFRM
-        return 1;
-#else
-        /* 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))
-                return 0;
-
-        /* 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!?! */
-                return 0;
-        }
-
-        /* 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);
-
-        /* modify the protocol (it's ESP!) */
-        iph->protocol = IPPROTO_ESP;
-
-        /* and let the caller know to send this into the ESP processor... */
-        return -1;
-#endif
-}
-
 /* returns:
  *  -1: error
  *   0: success
@@ -1044,44 +942,36 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 
         if (up->encap_type) {
                 /*
-                 * This is an encapsulation socket, so let's see if this is
-                 * an encapsulated packet.
-                 * If it's a keepalive packet, then just eat it.
-                 * If it's an encapsulateed packet, then pass it to the
-                 * IPsec xfrm input and return the response
-                 * appropriately.  Otherwise, just fall through and
-                 * pass this up the UDP socket.
+                 * This is an encapsulation socket so pass the skb to
+                 * the socket's udp_encap_rcv() hook. Otherwise, just
+                 * fall through and pass this up the UDP socket.
+                 * up->encap_rcv() returns the following value:
+                 * =0 if skb was successfully passed to the encap
+                 *    handler or was discarded by it.
+                 * >0 if skb should be passed on to UDP.
+                 * <0 if skb should be resubmitted as proto -N
                  */
-                int ret;
+                unsigned int len;
 
-                ret = udp_encap_rcv(sk, skb);
-                if (ret == 0) {
-                        /* Eat the packet .. */
-                        kfree_skb(skb);
-                        return 0;
-                }
-                if (ret == -1) {
-                        /* process the ESP packet */
-                        ret = xfrm4_rcv_encap(skb, up->encap_type);
-                        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
-                        return -ret;
-                }
-                if (ret == -2) {
-                        /* process the L2TP packet */
-                        if (up->encap_rcv != NULL) {
-                                ret = (*up->encap_rcv)(sk, skb);
-                                if (ret <= 0) {
-                                        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
-                                        return ret;
-                                }
-
-                                /* FALLTHROUGH -- pass up as UDP packet */
+                /* if we're overly short, let UDP handle it */
+                len = skb->len - sizeof(struct udphdr);
+                if (len <= 0)
+                        goto udp;
+
+                if (up->encap_rcv != NULL) {
+                        int ret;
+
+                        ret = (*up->encap_rcv)(sk, skb);
+                        if (ret <= 0) {
+                                UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
+                                return -ret;
                         }
                 }
 
                 /* FALLTHROUGH -- it's a UDP Packet */
         }
 
+udp:
         /*
          *      UDP-Lite specific tests, ignored on UDP sockets
          */
@@ -1367,6 +1257,8 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
                 case 0:
                 case UDP_ENCAP_ESPINUDP:
                 case UDP_ENCAP_ESPINUDP_NON_IKE:
+                        up->encap_rcv = xfrm4_udp_encap_rcv;
+                        /* FALLTHROUGH */
                 case UDP_ENCAP_L2TPINUDP:
                         up->encap_type = val;
                         break;