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