[IPSEC]: Kill post_input hook and do NAT-T in esp_input directly
Herbert Xu [Mon, 27 Feb 2006 21:00:40 +0000 (13:00 -0800)]
The only reason post_input exists at all is that it gives us the
potential to adjust the checksums incrementally in future which
we ought to do.

However, after thinking about it for a bit we can adjust the
checksums without using this post_input stuff at all.  The crucial
point is that only the inner-most NAT-T SA needs to be considered
when adjusting checksums.  What's more, the checksum adjustment
comes down to a single u32 due to the linearity of IP checksums.

We just happen to have a spare u32 lying around in our skb structure :)
When ip_summed is set to CHECKSUM_NONE on input, the value of skb->csum
is currently unused.  All we have to do is to make that the checksum
adjustment and voila, there goes all the post_input and decap structures!

I've left in the decap data structures for now since it's intricately
woven into the sec_path stuff.  We can kill them later too.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/xfrm.h
net/ipv4/esp4.c
net/xfrm/xfrm_policy.c

index 004e645..8d362c4 100644 (file)
@@ -233,7 +233,6 @@ struct xfrm_type
        int                     (*init_state)(struct xfrm_state *x);
        void                    (*destructor)(struct xfrm_state *);
        int                     (*input)(struct xfrm_state *, struct xfrm_decap_state *, struct sk_buff *skb);
-       int                     (*post_input)(struct xfrm_state *, struct xfrm_decap_state *, struct sk_buff *skb);
        int                     (*output)(struct xfrm_state *, struct sk_buff *pskb);
        /* Estimate maximal size of result of transformation of a dgram */
        u32                     (*get_max_size)(struct xfrm_state *, int size);
index 3f47419..09590f3 100644 (file)
 #include <net/protocol.h>
 #include <net/udp.h>
 
-/* decapsulation data for use when post-processing */
-struct esp_decap_data {
-       xfrm_address_t  saddr;
-       __u16           sport;
-       __u8            proto;
-};
-
 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 {
        int err;
@@ -210,25 +203,47 @@ static int esp_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struc
 
        /* ... check padding bits here. Silly. :-) */ 
 
-       if (x->encap && decap && decap->decap_type) {
-               struct esp_decap_data *encap_data;
-               struct udphdr *uh = (struct udphdr *) (iph+1);
-
-               encap_data = (struct esp_decap_data *) (decap->decap_data);
-               encap_data->proto = 0;
-
-               switch (decap->decap_type) {
-               case UDP_ENCAP_ESPINUDP:
-               case UDP_ENCAP_ESPINUDP_NON_IKE:
-                       encap_data->proto = AF_INET;
-                       encap_data->saddr.a4 = iph->saddr;
-                       encap_data->sport = uh->source;
-                       encap_len = (void*)esph - (void*)uh;
-                       break;
+       if (x->encap) {
+               struct xfrm_encap_tmpl *encap = x->encap;
+               struct udphdr *uh;
 
-               default:
+               if (encap->encap_type != decap->decap_type)
                        goto out;
+
+               uh = (struct udphdr *)(iph + 1);
+               encap_len = (void*)esph - (void*)uh;
+
+               /*
+                * 1) if the NAT-T peer's IP or port changed then
+                *    advertize the change to the keying daemon.
+                *    This is an inbound SA, so just compare
+                *    SRC ports.
+                */
+               if (iph->saddr != x->props.saddr.a4 ||
+                   uh->source != encap->encap_sport) {
+                       xfrm_address_t ipaddr;
+
+                       ipaddr.a4 = iph->saddr;
+                       km_new_mapping(x, &ipaddr, uh->source);
+                               
+                       /* XXX: perhaps add an extra
+                        * policy check here, to see
+                        * if we should allow or
+                        * reject a packet from a
+                        * different source
+                        * address/port.
+                        */
                }
+       
+               /*
+                * 2) ignore UDP/TCP checksums in case
+                *    of NAT-T in Transport Mode, or
+                *    perform other post-processing fixes
+                *    as per draft-ietf-ipsec-udp-encaps-06,
+                *    section 3.1.2
+                */
+               if (!x->props.mode)
+                       skb->ip_summed = CHECKSUM_UNNECESSARY;
        }
 
        iph->protocol = nexthdr[1];
@@ -245,63 +260,6 @@ out:
        return -EINVAL;
 }
 
-static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
-{
-  
-       if (x->encap) {
-               struct xfrm_encap_tmpl *encap;
-               struct esp_decap_data *decap_data;
-
-               encap = x->encap;
-               decap_data = (struct esp_decap_data *)(decap->decap_data);
-
-               /* first, make sure that the decap type == the encap type */
-               if (encap->encap_type != decap->decap_type)
-                       return -EINVAL;
-
-               switch (encap->encap_type) {
-               default:
-               case UDP_ENCAP_ESPINUDP:
-               case UDP_ENCAP_ESPINUDP_NON_IKE:
-                       /*
-                        * 1) if the NAT-T peer's IP or port changed then
-                        *    advertize the change to the keying daemon.
-                        *    This is an inbound SA, so just compare
-                        *    SRC ports.
-                        */
-                       if (decap_data->proto == AF_INET &&
-                           (decap_data->saddr.a4 != x->props.saddr.a4 ||
-                            decap_data->sport != encap->encap_sport)) {
-                               xfrm_address_t ipaddr;
-
-                               ipaddr.a4 = decap_data->saddr.a4;
-                               km_new_mapping(x, &ipaddr, decap_data->sport);
-                                       
-                               /* XXX: perhaps add an extra
-                                * policy check here, to see
-                                * if we should allow or
-                                * reject a packet from a
-                                * different source
-                                * address/port.
-                                */
-                       }
-               
-                       /*
-                        * 2) ignore UDP/TCP checksums in case
-                        *    of NAT-T in Transport Mode, or
-                        *    perform other post-processing fixes
-                        *    as per * draft-ietf-ipsec-udp-encaps-06,
-                        *    section 3.1.2
-                        */
-                       if (!x->props.mode)
-                               skb->ip_summed = CHECKSUM_UNNECESSARY;
-
-                       break;
-               }
-       }
-       return 0;
-}
-
 static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
 {
        struct esp_data *esp = x->data;
@@ -457,7 +415,6 @@ static struct xfrm_type esp_type =
        .destructor     = esp_destroy,
        .get_max_size   = esp4_get_max_size,
        .input          = esp_input,
-       .post_input     = esp_post_input,
        .output         = esp_output
 };
 
@@ -469,15 +426,6 @@ static struct net_protocol esp4_protocol = {
 
 static int __init esp4_init(void)
 {
-       struct xfrm_decap_state decap;
-
-       if (sizeof(struct esp_decap_data)  >
-           sizeof(decap.decap_data)) {
-               extern void decap_data_too_small(void);
-
-               decap_data_too_small();
-       }
-
        if (xfrm_register_type(&esp_type, AF_INET) < 0) {
                printk(KERN_INFO "ip esp init: can't add xfrm type\n");
                return -EAGAIN;
index 8206025..ae62054 100644 (file)
@@ -996,13 +996,6 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
                        struct sec_decap_state *xvec = &(skb->sp->x[i]);
                        if (!xfrm_selector_match(&xvec->xvec->sel, &fl, family))
                                return 0;
-
-                       /* If there is a post_input processor, try running it */
-                       if (xvec->xvec->type->post_input &&
-                           (xvec->xvec->type->post_input)(xvec->xvec,
-                                                          &(xvec->decap),
-                                                          skb) != 0)
-                               return 0;
                }
        }