/*
* 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/ah.c.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/ah.h>
#include <linux/crypto.h>
#include <linux/pfkeyv2.h>
#include <linux/string.h>
#include <net/icmp.h>
#include <net/ipv6.h>
#include <net/xfrm.h>
#include <asm/scatterlist.h>
static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
{
u8 *opt = (u8 *)opthdr;
int len = ipv6_optlen(opthdr);
int off = 0;
int optlen = 0;
off += 2;
len -= 2;
while (len > 0) {
switch (opt[off]) {
case IPV6_TLV_PAD0:
optlen = 1;
break;
default:
if (len < 2)
goto bad;
optlen = opt[off+1]+2;
if (len < optlen)
goto bad;
if (opt[off] & 0x20)
memset(&opt[off+2], 0, opt[off+1]);
break;
}
off += optlen;
len -= optlen;
}
if (len == 0)
return 1;
bad:
return 0;
}
/**
* ipv6_rearrange_rthdr - rearrange IPv6 routing header
* @iph: IPv6 header
* @rthdr: routing header
*
* Rearrange the destination address in @iph and the addresses in @rthdr
* so that they appear in the order they will at the final destination.
* See Appendix A2 of RFC 2402 for details.
*/
static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
{
int segments, segments_left;
struct in6_addr *addrs;
struct in6_addr final_addr;
segments_left = rthdr->segments_left;
if (segments_left == 0)
return;
rthdr->segments_left = 0;
/* The value of rthdr->hdrlen has been verified either by the system
* call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
* packets. So we can assume that it is even and that segments is
* greater than or equal to segments_left.
*
* For the same reason we can assume that this option is of type 0.
*/
segments = rthdr->hdrlen >> 1;
addrs = ((struct rt0_hdr *)rthdr)->addr;
ipv6_addr_copy(&final_addr, addrs + segments - 1);
addrs += segments - segments_left;
memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
ipv6_addr_copy(addrs, &iph->daddr);
ipv6_addr_copy(&iph->daddr, &final_addr);
}
static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
{
union {
struct ipv6hdr *iph;
struct ipv6_opt_hdr *opth;
struct ipv6_rt_hdr *rth;
char *raw;
} exthdr = { .iph = iph };
char *end = exthdr.raw + len;
int nexthdr = iph->nexthdr;
exthdr.iph++;
while (exthdr.raw < end) {
switch (nexthdr) {
case NEXTHDR_HOP:
case NEXTHDR_DEST:
if (!zero_out_mutable_opts(exthdr.opth)) {
LIMIT_NETDEBUG(printk(
KERN_WARNING "overrun %sopts\n",
nexthdr == NEXTHDR_HOP ?
"hop" : "dest"));
return -EINVAL;
}
break;
case NEXTHDR_ROUTING:
ipv6_rearrange_rthdr(iph, exthdr.rth);
break;
default :
return 0;
}
nexthdr = exthdr.opth->nexthdr;
exthdr.raw += ipv6_optlen(exthdr.opth);
}
return 0;
}
static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
int extlen;
struct ipv6hdr *top_iph;
struct ip_auth_hdr *ah;
struct ah_data *ahp;
u8 nexthdr;
char tmp_base[8];
struct {
struct in6_addr daddr;
char hdrs[0];
} *tmp_ext;
top_iph = (struct ipv6hdr *)skb->data;
top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
nexthdr = *skb->nh.raw;
*skb->nh.raw = IPPROTO_AH;
/* When there are no extension headers, we only need to save the first
* 8 bytes of the base IP header.
*/
memcpy(tmp_base, top_iph, sizeof(tmp_base));
tmp_ext = NULL;
extlen = skb->h.raw - (unsigned char *)(top_iph + 1);
if (extlen) {
extlen += sizeof(*tmp_ext);
tmp_ext = kmalloc(extlen, GFP_ATOMIC);
if (!tmp_ext) {
err = -ENOMEM;
goto error;
}
memcpy(tmp_ext, &top_iph->daddr, extlen);
err = ipv6_clear_mutable_options(top_iph,
extlen - sizeof(*tmp_ext) +
sizeof(*top_iph));
if (err)
goto error_free_iph;
}
ah = (struct ip_auth_hdr *)skb->h.raw;
ah->nexthdr = nexthdr;
top_iph->priority = 0;
top_iph->flow_lbl[0] = 0;
top_iph->flow_lbl[1] = 0;
top_iph->flow_lbl[2] = 0;
top_iph->hop_limit = 0;
ahp = x->data;
ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) +
ahp->icv_trunc_len) >> 2) - 2;
ah->reserved = 0;
ah->spi = x->id.spi;
ah->seq_no = htonl(++x->replay.oseq);
ahp->icv(ahp, skb, ah->auth_data);
err = 0;
memcpy(top_iph, tmp_base, sizeof(tmp_base));
if (tmp_ext) {
memcpy(&top_iph->daddr, tmp_ext, extlen);
error_free_iph:
kfree(tmp_ext);
}
error:
return err;
}
static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
{
/*
* Before process AH
* [IPv6][Ext1][Ext2][AH][Dest][Payload]
* |<-------------->| hdr_len
*
* To erase AH:
* Keeping copy of cleared headers. After AH processing,
* Moving the pointer of skb->nh.raw by using skb_pull as long as AH
* header length. Then copy back the copy as long as hdr_len
* If destination header following AH exists, copy it into after [Ext2].
*
* |<>|[IPv6][Ext1][Ext2][Dest][Payload]
* There is offset of AH before IPv6 header after the process.
*/
struct ipv6_auth_hdr *ah;
struct ah_data *ahp;
unsigned char *tmp_hdr = NULL;
u16 hdr_len;
u16 ah_hlen;
int nexthdr;
if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
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;
hdr_len = skb->data - skb->nh.raw;
ah = (struct ipv6_auth_hdr*)skb->data;
ahp = x->data;
nexthdr = ah->nexthdr;
ah_hlen = (ah->hdrlen + 2) << 2;
if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) &&
ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len))
goto out;
if (!pskb_may_pull(skb, ah_hlen))
goto out;
tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
if (!tmp_hdr)
goto out;
memcpy(tmp_hdr, skb->nh.raw, hdr_len);
if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
goto out;
skb->nh.ipv6h->priority = 0;
skb->nh.ipv6h->flow_lbl[0] = 0;
skb->nh.ipv6h->flow_lbl[1] = 0;
skb->nh.ipv6h->flow_lbl[2] = 0;
skb->nh.ipv6h->hop_limit = 0;
{
u8 auth_data[MAX_AH_AUTH_LEN];
memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
memset(ah->auth_data, 0, ahp->icv_trunc_len);
skb_push(skb, skb->data - skb->nh.raw);
ahp->icv(ahp, skb, ah->auth_data);
if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
LIMIT_NETDEBUG(
printk(KERN_WARNING "ipsec ah authentication error\n"));
x->stats.integrity_failed++;
goto free_out;
}
}
skb->nh.raw = skb_pull(skb, ah_hlen);
memcpy(skb->nh.raw, tmp_hdr, hdr_len);
skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
skb_pull(skb, hdr_len);
skb->h.raw = skb->data;
kfree(tmp_hdr);
return nexthdr;
free_out:
kfree(tmp_hdr);
out:
return -EINVAL;
}
static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
int type, int code, int offset, __u32 info)
{
struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
struct ip_auth_hdr *ah = (struct ip_auth_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, ah->spi, IPPROTO_AH, AF_INET6);
if (!x)
return;
NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/"
"%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
ntohl(ah->spi), NIP6(iph->daddr)));
xfrm_state_put(x);
}
static int ah6_init_state(struct xfrm_state *x, void *args)
{
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 ipv6_auth_hdr) + ahp->icv_trunc_len);
if (x->props.mode)
x->props.header_len += sizeof(struct ipv6hdr);
x->data = ahp;
return 0;
error:
if (ahp) {
if (ahp->work_icv)
kfree(ahp->work_icv);
if (ahp->tfm)
crypto_free_tfm(ahp->tfm);
kfree(ahp);
}
return -EINVAL;
}
static void ah6_destroy(struct xfrm_state *x)
{
struct ah_data *ahp = x->data;
if (!ahp)
return;
if (ahp->work_icv) {
kfree(ahp->work_icv);
ahp->work_icv = NULL;
}
if (ahp->tfm) {
crypto_free_tfm(ahp->tfm);
ahp->tfm = NULL;
}
kfree(ahp);
}
static struct xfrm_type ah6_type =
{
.description = "AH6",
.owner = THIS_MODULE,
.proto = IPPROTO_AH,
.init_state = ah6_init_state,
.destructor = ah6_destroy,
.input = ah6_input,
.output = ah6_output
};
static struct inet6_protocol ah6_protocol = {
.handler = xfrm6_rcv,
.err_handler = ah6_err,
.flags = INET6_PROTO_NOPOLICY,
};
static int __init ah6_init(void)
{
if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
return -EAGAIN;
}
if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
xfrm_unregister_type(&ah6_type, AF_INET6);
return -EAGAIN;
}
return 0;
}
static void __exit ah6_fini(void)
{
if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
}
module_init(ah6_init);
module_exit(ah6_fini);
MODULE_LICENSE("GPL");
