linux/net/ipv4/xfrm4_input.c
Herbert Xu 227620e295 [IPSEC]: Separate inner/outer mode processing on input
With inter-family transforms the inner mode differs from the outer
mode.  Attempting to handle both sides from the same function means
that it needs to handle both IPv4 and IPv6 which creates duplication
and confusion.

This patch separates the two parts on the input path so that each
function deals with one family only.

In particular, the functions xfrm4_extract_inut/xfrm6_extract_inut
moves the pertinent fields from the IPv4/IPv6 IP headers into a
neutral format stored in skb->cb.  This is then used by the inner mode
input functions to modify the inner IP header.  In this way the input
function no longer has to know about the outer address family.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:53:46 -08:00

264 lines
5.9 KiB
C

/*
* 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);
}
#ifdef CONFIG_NETFILTER
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;
}
#endif
int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
int encap_type)
{
int err;
__be32 seq;
struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
struct xfrm_state *x;
int xfrm_nr = 0;
int decaps = 0;
unsigned int nhoff = offsetof(struct iphdr, protocol);
seq = 0;
if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0)
goto drop;
do {
const struct iphdr *iph = ip_hdr(skb);
if (xfrm_nr == XFRM_MAX_DEPTH)
goto drop;
x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi,
nexthdr, AF_INET);
if (x == NULL)
goto drop;
spin_lock(&x->lock);
if (unlikely(x->km.state != XFRM_STATE_VALID))
goto drop_unlock;
if ((x->encap ? x->encap->encap_type : 0) != encap_type)
goto drop_unlock;
if (x->props.replay_window && xfrm_replay_check(x, seq))
goto drop_unlock;
if (xfrm_state_check_expire(x))
goto drop_unlock;
nexthdr = x->type->input(x, skb);
if (nexthdr <= 0)
goto drop_unlock;
skb_network_header(skb)[nhoff] = nexthdr;
/* only the first xfrm gets the encap type */
encap_type = 0;
if (x->props.replay_window)
xfrm_replay_advance(x, seq);
x->curlft.bytes += skb->len;
x->curlft.packets++;
spin_unlock(&x->lock);
xfrm_vec[xfrm_nr++] = x;
if (x->inner_mode->input(x, skb))
goto drop;
if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
decaps = 1;
break;
}
err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
if (err < 0)
goto drop;
} while (!err);
/* Allocate new secpath or COW existing one. */
if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
struct sec_path *sp;
sp = secpath_dup(skb->sp);
if (!sp)
goto drop;
if (skb->sp)
secpath_put(skb->sp);
skb->sp = sp;
}
if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
goto drop;
memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
xfrm_nr * sizeof(xfrm_vec[0]));
skb->sp->len += xfrm_nr;
nf_reset(skb);
if (decaps) {
dst_release(skb->dst);
skb->dst = NULL;
netif_rx(skb);
return 0;
} else {
#ifdef CONFIG_NETFILTER
__skb_push(skb, skb->data - skb_network_header(skb));
ip_hdr(skb)->tot_len = htons(skb->len);
ip_send_check(ip_hdr(skb));
NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
xfrm4_rcv_encap_finish);
return 0;
#else
return -ip_hdr(skb)->protocol;
#endif
}
drop_unlock:
spin_unlock(&x->lock);
xfrm_state_put(x);
drop:
while (--xfrm_nr >= 0)
xfrm_state_put(xfrm_vec[xfrm_nr]);
kfree_skb(skb);
return 0;
}
EXPORT_SYMBOL(xfrm4_rcv_encap);
/* 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);