linux/net/ipv6/esp6.c
Herbert Xu ceb1eec829 [IPSEC]: Move IP length/checksum setting out of transforms
This patch moves the setting of the IP length and checksum fields out of
the transforms and into the xfrmX_output functions.  This would help future
efforts in merging the transforms themselves.

It also adds an optimisation to ipcomp due to the fact that the transport
offset is guaranteed to be zero.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:55:56 -07:00

416 lines
10 KiB
C

/*
* Copyright (C)2002 USAGI/WIDE Project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Authors
*
* Mitsuru KANDA @USAGI : IPv6 Support
* Kazunori MIYAZAWA @USAGI :
* Kunihiro Ishiguro <kunihiro@ipinfusion.com>
*
* This file is derived from net/ipv4/esp.c
*/
#include <linux/err.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/esp.h>
#include <asm/scatterlist.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/pfkeyv2.h>
#include <linux/random.h>
#include <linux/spinlock.h>
#include <net/icmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <linux/icmpv6.h>
static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
struct ip_esp_hdr *esph;
struct crypto_blkcipher *tfm;
struct blkcipher_desc desc;
struct sk_buff *trailer;
int blksize;
int clen;
int alen;
int nfrags;
u8 *tail;
struct esp_data *esp = x->data;
/* skb is pure payload to encrypt */
err = -ENOMEM;
/* Round to block size */
clen = skb->len;
alen = esp->auth.icv_trunc_len;
tfm = esp->conf.tfm;
desc.tfm = tfm;
desc.flags = 0;
blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
clen = ALIGN(clen + 2, blksize);
if (esp->conf.padlen)
clen = ALIGN(clen, esp->conf.padlen);
if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) {
goto error;
}
/* Fill padding... */
tail = skb_tail_pointer(trailer);
do {
int i;
for (i=0; i<clen-skb->len - 2; i++)
tail[i] = i + 1;
} while (0);
tail[clen-skb->len - 2] = (clen - skb->len) - 2;
pskb_put(skb, trailer, clen - skb->len);
skb_push(skb, -skb_network_offset(skb));
esph = ip_esp_hdr(skb);
*(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb);
*skb_mac_header(skb) = IPPROTO_ESP;
esph->spi = x->id.spi;
esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
spin_lock_bh(&x->lock);
if (esp->conf.ivlen) {
if (unlikely(!esp->conf.ivinitted)) {
get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
esp->conf.ivinitted = 1;
}
crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
}
do {
struct scatterlist *sg = &esp->sgbuf[0];
if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
if (!sg)
goto unlock;
}
skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
if (unlikely(sg != &esp->sgbuf[0]))
kfree(sg);
} while (0);
if (unlikely(err))
goto unlock;
if (esp->conf.ivlen) {
memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
}
if (esp->auth.icv_full_len) {
err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
sizeof(*esph) + esp->conf.ivlen + clen);
memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
}
unlock:
spin_unlock_bh(&x->lock);
error:
return err;
}
static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
{
struct ipv6hdr *iph;
struct ip_esp_hdr *esph;
struct esp_data *esp = x->data;
struct crypto_blkcipher *tfm = esp->conf.tfm;
struct blkcipher_desc desc = { .tfm = tfm };
struct sk_buff *trailer;
int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
int alen = esp->auth.icv_trunc_len;
int elen = skb->len - sizeof(*esph) - esp->conf.ivlen - alen;
int hdr_len = skb_network_header_len(skb);
int nfrags;
int ret = 0;
if (!pskb_may_pull(skb, sizeof(*esph))) {
ret = -EINVAL;
goto out;
}
if (elen <= 0 || (elen & (blksize-1))) {
ret = -EINVAL;
goto out;
}
/* If integrity check is required, do this. */
if (esp->auth.icv_full_len) {
u8 sum[alen];
ret = esp_mac_digest(esp, skb, 0, skb->len - alen);
if (ret)
goto out;
if (skb_copy_bits(skb, skb->len - alen, sum, alen))
BUG();
if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
x->stats.integrity_failed++;
ret = -EINVAL;
goto out;
}
}
if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
ret = -EINVAL;
goto out;
}
skb->ip_summed = CHECKSUM_NONE;
esph = (struct ip_esp_hdr *)skb->data;
iph = ipv6_hdr(skb);
/* Get ivec. This can be wrong, check against another impls. */
if (esp->conf.ivlen)
crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
{
u8 nexthdr[2];
struct scatterlist *sg = &esp->sgbuf[0];
u8 padlen;
if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
if (!sg) {
ret = -ENOMEM;
goto out;
}
}
skb_to_sgvec(skb, sg, sizeof(*esph) + esp->conf.ivlen, elen);
ret = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
if (unlikely(sg != &esp->sgbuf[0]))
kfree(sg);
if (unlikely(ret))
goto out;
if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
BUG();
padlen = nexthdr[0];
if (padlen+2 >= elen) {
LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage padlen=%d, elen=%d\n", padlen+2, elen);
ret = -EINVAL;
goto out;
}
/* ... check padding bits here. Silly. :-) */
pskb_trim(skb, skb->len - alen - padlen - 2);
ret = nexthdr[1];
}
__skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
skb_set_transport_header(skb, -hdr_len);
out:
return ret;
}
static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
{
struct esp_data *esp = x->data;
u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
u32 align = max_t(u32, blksize, esp->conf.padlen);
u32 rem;
mtu -= x->props.header_len + esp->auth.icv_trunc_len;
rem = mtu & (align - 1);
mtu &= ~(align - 1);
if (x->props.mode != XFRM_MODE_TUNNEL) {
u32 padsize = ((blksize - 1) & 7) + 1;
mtu -= blksize - padsize;
mtu += min_t(u32, blksize - padsize, rem);
}
return mtu - 2;
}
static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
int type, int code, int offset, __be32 info)
{
struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);
struct xfrm_state *x;
if (type != ICMPV6_DEST_UNREACH &&
type != ICMPV6_PKT_TOOBIG)
return;
x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET6);
if (!x)
return;
printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/" NIP6_FMT "\n",
ntohl(esph->spi), NIP6(iph->daddr));
xfrm_state_put(x);
}
static void esp6_destroy(struct xfrm_state *x)
{
struct esp_data *esp = x->data;
if (!esp)
return;
crypto_free_blkcipher(esp->conf.tfm);
esp->conf.tfm = NULL;
kfree(esp->conf.ivec);
esp->conf.ivec = NULL;
crypto_free_hash(esp->auth.tfm);
esp->auth.tfm = NULL;
kfree(esp->auth.work_icv);
esp->auth.work_icv = NULL;
kfree(esp);
}
static int esp6_init_state(struct xfrm_state *x)
{
struct esp_data *esp = NULL;
struct crypto_blkcipher *tfm;
if (x->ealg == NULL)
goto error;
if (x->encap)
goto error;
esp = kzalloc(sizeof(*esp), GFP_KERNEL);
if (esp == NULL)
return -ENOMEM;
if (x->aalg) {
struct xfrm_algo_desc *aalg_desc;
struct crypto_hash *hash;
hash = crypto_alloc_hash(x->aalg->alg_name, 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(hash))
goto error;
esp->auth.tfm = hash;
if (crypto_hash_setkey(hash, x->aalg->alg_key,
(x->aalg->alg_key_len + 7) / 8))
goto error;
aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
BUG_ON(!aalg_desc);
if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
crypto_hash_digestsize(hash)) {
NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
x->aalg->alg_name,
crypto_hash_digestsize(hash),
aalg_desc->uinfo.auth.icv_fullbits/8);
goto error;
}
esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
if (!esp->auth.work_icv)
goto error;
}
tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
goto error;
esp->conf.tfm = tfm;
esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
esp->conf.padlen = 0;
if (esp->conf.ivlen) {
esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
if (unlikely(esp->conf.ivec == NULL))
goto error;
esp->conf.ivinitted = 0;
}
if (crypto_blkcipher_setkey(tfm, x->ealg->alg_key,
(x->ealg->alg_key_len + 7) / 8))
goto error;
x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
if (x->props.mode == XFRM_MODE_TUNNEL)
x->props.header_len += sizeof(struct ipv6hdr);
x->data = esp;
return 0;
error:
x->data = esp;
esp6_destroy(x);
x->data = NULL;
return -EINVAL;
}
static struct xfrm_type esp6_type =
{
.description = "ESP6",
.owner = THIS_MODULE,
.proto = IPPROTO_ESP,
.flags = XFRM_TYPE_REPLAY_PROT,
.init_state = esp6_init_state,
.destructor = esp6_destroy,
.get_mtu = esp6_get_mtu,
.input = esp6_input,
.output = esp6_output,
.hdr_offset = xfrm6_find_1stfragopt,
};
static struct inet6_protocol esp6_protocol = {
.handler = xfrm6_rcv,
.err_handler = esp6_err,
.flags = INET6_PROTO_NOPOLICY,
};
static int __init esp6_init(void)
{
if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
printk(KERN_INFO "ipv6 esp init: can't add xfrm type\n");
return -EAGAIN;
}
if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
printk(KERN_INFO "ipv6 esp init: can't add protocol\n");
xfrm_unregister_type(&esp6_type, AF_INET6);
return -EAGAIN;
}
return 0;
}
static void __exit esp6_fini(void)
{
if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
printk(KERN_INFO "ipv6 esp close: can't remove protocol\n");
if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
printk(KERN_INFO "ipv6 esp close: can't remove xfrm type\n");
}
module_init(esp6_init);
module_exit(esp6_fini);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);