linux/net/ipv6/ah6.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

467 lines
11 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/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/protocol.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(
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);
xfrm_aevent_doreplay(x);
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 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 free_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, hdr_len);
ahp->icv(ahp, skb, ah->auth_data);
if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
x->stats.integrity_failed++;
goto free_out;
}
}
skb->h.raw = memcpy(skb->nh.raw += ah_hlen, tmp_hdr, hdr_len);
__skb_pull(skb, ah_hlen + hdr_len);
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(KERN_DEBUG "pmtu discovery on SA AH/%08x/" NIP6_FMT "\n",
ntohl(ah->spi), NIP6(iph->daddr));
xfrm_state_put(x);
}
static int ah6_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 = kzalloc(sizeof(*ahp), GFP_KERNEL);
if (ahp == NULL)
return -ENOMEM;
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) {
kfree(ahp->work_icv);
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;
kfree(ahp->work_icv);
ahp->work_icv = NULL;
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");