linux/net/ipv4/ah4.c
Herbert Xu 31a4ab9302 [IPSEC] proto: Move transport mode input path into xfrm_mode_transport
Now that we have xfrm_mode objects we can move the transport mode specific
input decapsulation code into xfrm_mode_transport.  This removes duplicate
code as well as unnecessary header movement in case of tunnel mode SAs
since we will discard the original IP header immediately.

This also fixes a minor bug for transport-mode ESP where the IP payload
length is set to the correct value minus the header length (with extension
headers for IPv6).

Of course the other neat thing is that we no longer have to allocate
temporary buffers to hold the IP headers for ESP and IPComp.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-17 21:28:41 -07:00

331 lines
7.4 KiB
C

#include <linux/config.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/ah.h>
#include <linux/crypto.h>
#include <linux/pfkeyv2.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <asm/scatterlist.h>
/* Clear mutable options and find final destination to substitute
* into IP header for icv calculation. Options are already checked
* for validity, so paranoia is not required. */
static int ip_clear_mutable_options(struct iphdr *iph, u32 *daddr)
{
unsigned char * optptr = (unsigned char*)(iph+1);
int l = iph->ihl*4 - sizeof(struct iphdr);
int optlen;
while (l > 0) {
switch (*optptr) {
case IPOPT_END:
return 0;
case IPOPT_NOOP:
l--;
optptr++;
continue;
}
optlen = optptr[1];
if (optlen<2 || optlen>l)
return -EINVAL;
switch (*optptr) {
case IPOPT_SEC:
case 0x85: /* Some "Extended Security" crap. */
case 0x86: /* Another "Commercial Security" crap. */
case IPOPT_RA:
case 0x80|21: /* RFC1770 */
break;
case IPOPT_LSRR:
case IPOPT_SSRR:
if (optlen < 6)
return -EINVAL;
memcpy(daddr, optptr+optlen-4, 4);
/* Fall through */
default:
memset(optptr+2, 0, optlen-2);
}
l -= optlen;
optptr += optlen;
}
return 0;
}
static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
struct iphdr *iph, *top_iph;
struct ip_auth_hdr *ah;
struct ah_data *ahp;
union {
struct iphdr iph;
char buf[60];
} tmp_iph;
top_iph = skb->nh.iph;
iph = &tmp_iph.iph;
iph->tos = top_iph->tos;
iph->ttl = top_iph->ttl;
iph->frag_off = top_iph->frag_off;
if (top_iph->ihl != 5) {
iph->daddr = top_iph->daddr;
memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
if (err)
goto error;
}
ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4);
ah->nexthdr = top_iph->protocol;
top_iph->tos = 0;
top_iph->tot_len = htons(skb->len);
top_iph->frag_off = 0;
top_iph->ttl = 0;
top_iph->protocol = IPPROTO_AH;
top_iph->check = 0;
ahp = x->data;
ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
ahp->icv_trunc_len) >> 2) - 2;
ah->reserved = 0;
ah->spi = x->id.spi;
ah->seq_no = htonl(++x->replay.oseq);
xfrm_aevent_doreplay(x);
ahp->icv(ahp, skb, ah->auth_data);
top_iph->tos = iph->tos;
top_iph->ttl = iph->ttl;
top_iph->frag_off = iph->frag_off;
if (top_iph->ihl != 5) {
top_iph->daddr = iph->daddr;
memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
}
ip_send_check(top_iph);
err = 0;
error:
return err;
}
static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
{
int ah_hlen;
int ihl;
struct iphdr *iph;
struct ip_auth_hdr *ah;
struct ah_data *ahp;
char work_buf[60];
if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
goto out;
ah = (struct ip_auth_hdr*)skb->data;
ahp = x->data;
ah_hlen = (ah->hdrlen + 2) << 2;
if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
goto out;
if (!pskb_may_pull(skb, ah_hlen))
goto out;
/* We are going to _remove_ AH header to keep sockets happy,
* so... Later this can change. */
if (skb_cloned(skb) &&
pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
goto out;
skb->ip_summed = CHECKSUM_NONE;
ah = (struct ip_auth_hdr*)skb->data;
iph = skb->nh.iph;
ihl = skb->data - skb->nh.raw;
memcpy(work_buf, iph, ihl);
iph->ttl = 0;
iph->tos = 0;
iph->frag_off = 0;
iph->check = 0;
if (ihl > sizeof(*iph)) {
u32 dummy;
if (ip_clear_mutable_options(iph, &dummy))
goto out;
}
{
u8 auth_data[MAX_AH_AUTH_LEN];
memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
skb_push(skb, ihl);
ahp->icv(ahp, skb, ah->auth_data);
if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
x->stats.integrity_failed++;
goto out;
}
}
((struct iphdr*)work_buf)->protocol = ah->nexthdr;
skb->h.raw = memcpy(skb->nh.raw += ah_hlen, work_buf, ihl);
__skb_pull(skb, ah_hlen + ihl);
return 0;
out:
return -EINVAL;
}
static void ah4_err(struct sk_buff *skb, u32 info)
{
struct iphdr *iph = (struct iphdr*)skb->data;
struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2));
struct xfrm_state *x;
if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
skb->h.icmph->code != ICMP_FRAG_NEEDED)
return;
x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
if (!x)
return;
printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
ntohl(ah->spi), ntohl(iph->daddr));
xfrm_state_put(x);
}
static int ah_init_state(struct xfrm_state *x)
{
struct ah_data *ahp = NULL;
struct xfrm_algo_desc *aalg_desc;
if (!x->aalg)
goto error;
/* null auth can use a zero length key */
if (x->aalg->alg_key_len > 512)
goto error;
if (x->encap)
goto error;
ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
if (ahp == NULL)
return -ENOMEM;
memset(ahp, 0, sizeof(*ahp));
ahp->key = x->aalg->alg_key;
ahp->key_len = (x->aalg->alg_key_len+7)/8;
ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
if (!ahp->tfm)
goto error;
ahp->icv = ah_hmac_digest;
/*
* Lookup the algorithm description maintained by xfrm_algo,
* verify crypto transform properties, and store information
* we need for AH processing. This lookup cannot fail here
* after a successful crypto_alloc_tfm().
*/
aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
BUG_ON(!aalg_desc);
if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
crypto_tfm_alg_digestsize(ahp->tfm)) {
printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
aalg_desc->uinfo.auth.icv_fullbits/8);
goto error;
}
ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
if (!ahp->work_icv)
goto error;
x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
if (x->props.mode)
x->props.header_len += sizeof(struct iphdr);
x->data = ahp;
return 0;
error:
if (ahp) {
kfree(ahp->work_icv);
crypto_free_tfm(ahp->tfm);
kfree(ahp);
}
return -EINVAL;
}
static void ah_destroy(struct xfrm_state *x)
{
struct ah_data *ahp = x->data;
if (!ahp)
return;
kfree(ahp->work_icv);
ahp->work_icv = NULL;
crypto_free_tfm(ahp->tfm);
ahp->tfm = NULL;
kfree(ahp);
}
static struct xfrm_type ah_type =
{
.description = "AH4",
.owner = THIS_MODULE,
.proto = IPPROTO_AH,
.init_state = ah_init_state,
.destructor = ah_destroy,
.input = ah_input,
.output = ah_output
};
static struct net_protocol ah4_protocol = {
.handler = xfrm4_rcv,
.err_handler = ah4_err,
.no_policy = 1,
};
static int __init ah4_init(void)
{
if (xfrm_register_type(&ah_type, AF_INET) < 0) {
printk(KERN_INFO "ip ah init: can't add xfrm type\n");
return -EAGAIN;
}
if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
printk(KERN_INFO "ip ah init: can't add protocol\n");
xfrm_unregister_type(&ah_type, AF_INET);
return -EAGAIN;
}
return 0;
}
static void __exit ah4_fini(void)
{
if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
printk(KERN_INFO "ip ah close: can't remove protocol\n");
if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
}
module_init(ah4_init);
module_exit(ah4_fini);
MODULE_LICENSE("GPL");