linux/net/ipv6/esp6.c
Thomas Graf 920fc941a9 [ESP]: Ensure IV is in linear part of the skb to avoid BUG() due to OOB access
ESP does not account for the IV size when calling pskb_may_pull() to
ensure everything it accesses directly is within the linear part of a
potential fragment. This results in a BUG() being triggered when the
both the IPv4 and IPv6 ESP stack is fed with an skb where the first
fragment ends between the end of the esp header and the end of the IV.

This bug was found by Dirk Nehring <dnehring@gmx.net> .

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-27 16:08:03 -07:00

589 lines
14 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 <crypto/aead.h>
#include <crypto/authenc.h>
#include <linux/err.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/esp.h>
#include <linux/scatterlist.h>
#include <linux/kernel.h>
#include <linux/pfkeyv2.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <net/icmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <linux/icmpv6.h>
struct esp_skb_cb {
struct xfrm_skb_cb xfrm;
void *tmp;
};
#define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
/*
* Allocate an AEAD request structure with extra space for SG and IV.
*
* For alignment considerations the IV is placed at the front, followed
* by the request and finally the SG list.
*
* TODO: Use spare space in skb for this where possible.
*/
static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)
{
unsigned int len;
len = crypto_aead_ivsize(aead);
if (len) {
len += crypto_aead_alignmask(aead) &
~(crypto_tfm_ctx_alignment() - 1);
len = ALIGN(len, crypto_tfm_ctx_alignment());
}
len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);
len = ALIGN(len, __alignof__(struct scatterlist));
len += sizeof(struct scatterlist) * nfrags;
return kmalloc(len, GFP_ATOMIC);
}
static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp)
{
return crypto_aead_ivsize(aead) ?
PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp;
}
static inline struct aead_givcrypt_request *esp_tmp_givreq(
struct crypto_aead *aead, u8 *iv)
{
struct aead_givcrypt_request *req;
req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
crypto_tfm_ctx_alignment());
aead_givcrypt_set_tfm(req, aead);
return req;
}
static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
{
struct aead_request *req;
req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
crypto_tfm_ctx_alignment());
aead_request_set_tfm(req, aead);
return req;
}
static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
struct aead_request *req)
{
return (void *)ALIGN((unsigned long)(req + 1) +
crypto_aead_reqsize(aead),
__alignof__(struct scatterlist));
}
static inline struct scatterlist *esp_givreq_sg(
struct crypto_aead *aead, struct aead_givcrypt_request *req)
{
return (void *)ALIGN((unsigned long)(req + 1) +
crypto_aead_reqsize(aead),
__alignof__(struct scatterlist));
}
static void esp_output_done(struct crypto_async_request *base, int err)
{
struct sk_buff *skb = base->data;
kfree(ESP_SKB_CB(skb)->tmp);
xfrm_output_resume(skb, err);
}
static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
struct ip_esp_hdr *esph;
struct crypto_aead *aead;
struct aead_givcrypt_request *req;
struct scatterlist *sg;
struct scatterlist *asg;
struct sk_buff *trailer;
void *tmp;
int blksize;
int clen;
int alen;
int nfrags;
u8 *iv;
u8 *tail;
struct esp_data *esp = x->data;
/* skb is pure payload to encrypt */
err = -ENOMEM;
/* Round to block size */
clen = skb->len;
aead = esp->aead;
alen = crypto_aead_authsize(aead);
blksize = ALIGN(crypto_aead_blocksize(aead), 4);
clen = ALIGN(clen + 2, blksize);
if (esp->padlen)
clen = ALIGN(clen, esp->padlen);
if ((err = skb_cow_data(skb, clen - skb->len + alen, &trailer)) < 0)
goto error;
nfrags = err;
tmp = esp_alloc_tmp(aead, nfrags + 1);
if (!tmp)
goto error;
iv = esp_tmp_iv(aead, tmp);
req = esp_tmp_givreq(aead, iv);
asg = esp_givreq_sg(aead, req);
sg = asg + 1;
/* 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;
tail[clen - skb->len - 1] = *skb_mac_header(skb);
pskb_put(skb, trailer, clen - skb->len + alen);
skb_push(skb, -skb_network_offset(skb));
esph = ip_esp_hdr(skb);
*skb_mac_header(skb) = IPPROTO_ESP;
esph->spi = x->id.spi;
esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);
sg_init_table(sg, nfrags);
skb_to_sgvec(skb, sg,
esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
clen + alen);
sg_init_one(asg, esph, sizeof(*esph));
aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
aead_givcrypt_set_assoc(req, asg, sizeof(*esph));
aead_givcrypt_set_giv(req, esph->enc_data,
XFRM_SKB_CB(skb)->seq.output);
ESP_SKB_CB(skb)->tmp = tmp;
err = crypto_aead_givencrypt(req);
if (err == -EINPROGRESS)
goto error;
if (err == -EBUSY)
err = NET_XMIT_DROP;
kfree(tmp);
error:
return err;
}
static int esp_input_done2(struct sk_buff *skb, int err)
{
struct xfrm_state *x = xfrm_input_state(skb);
struct esp_data *esp = x->data;
struct crypto_aead *aead = esp->aead;
int alen = crypto_aead_authsize(aead);
int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
int elen = skb->len - hlen;
int hdr_len = skb_network_header_len(skb);
int padlen;
u8 nexthdr[2];
kfree(ESP_SKB_CB(skb)->tmp);
if (unlikely(err))
goto out;
if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
BUG();
err = -EINVAL;
padlen = nexthdr[0];
if (padlen + 2 + alen >= elen) {
LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage "
"padlen=%d, elen=%d\n", padlen + 2, elen - alen);
goto out;
}
/* ... check padding bits here. Silly. :-) */
pskb_trim(skb, skb->len - alen - padlen - 2);
__skb_pull(skb, hlen);
skb_set_transport_header(skb, -hdr_len);
err = nexthdr[1];
/* RFC4303: Drop dummy packets without any error */
if (err == IPPROTO_NONE)
err = -EINVAL;
out:
return err;
}
static void esp_input_done(struct crypto_async_request *base, int err)
{
struct sk_buff *skb = base->data;
xfrm_input_resume(skb, esp_input_done2(skb, err));
}
static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
{
struct ip_esp_hdr *esph;
struct esp_data *esp = x->data;
struct crypto_aead *aead = esp->aead;
struct aead_request *req;
struct sk_buff *trailer;
int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
int nfrags;
int ret = 0;
void *tmp;
u8 *iv;
struct scatterlist *sg;
struct scatterlist *asg;
if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) {
ret = -EINVAL;
goto out;
}
if (elen <= 0) {
ret = -EINVAL;
goto out;
}
if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {
ret = -EINVAL;
goto out;
}
ret = -ENOMEM;
tmp = esp_alloc_tmp(aead, nfrags + 1);
if (!tmp)
goto out;
ESP_SKB_CB(skb)->tmp = tmp;
iv = esp_tmp_iv(aead, tmp);
req = esp_tmp_req(aead, iv);
asg = esp_req_sg(aead, req);
sg = asg + 1;
skb->ip_summed = CHECKSUM_NONE;
esph = (struct ip_esp_hdr *)skb->data;
/* Get ivec. This can be wrong, check against another impls. */
iv = esph->enc_data;
sg_init_table(sg, nfrags);
skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
sg_init_one(asg, esph, sizeof(*esph));
aead_request_set_callback(req, 0, esp_input_done, skb);
aead_request_set_crypt(req, sg, sg, elen, iv);
aead_request_set_assoc(req, asg, sizeof(*esph));
ret = crypto_aead_decrypt(req);
if (ret == -EINPROGRESS)
goto out;
ret = esp_input_done2(skb, ret);
out:
return ret;
}
static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
{
struct esp_data *esp = x->data;
u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);
u32 align = max_t(u32, blksize, esp->padlen);
u32 rem;
mtu -= x->props.header_len + crypto_aead_authsize(esp->aead);
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_aead(esp->aead);
kfree(esp);
}
static int esp_init_aead(struct xfrm_state *x)
{
struct esp_data *esp = x->data;
struct crypto_aead *aead;
int err;
aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);
err = PTR_ERR(aead);
if (IS_ERR(aead))
goto error;
esp->aead = aead;
err = crypto_aead_setkey(aead, x->aead->alg_key,
(x->aead->alg_key_len + 7) / 8);
if (err)
goto error;
err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);
if (err)
goto error;
error:
return err;
}
static int esp_init_authenc(struct xfrm_state *x)
{
struct esp_data *esp = x->data;
struct crypto_aead *aead;
struct crypto_authenc_key_param *param;
struct rtattr *rta;
char *key;
char *p;
char authenc_name[CRYPTO_MAX_ALG_NAME];
unsigned int keylen;
int err;
err = -EINVAL;
if (x->ealg == NULL)
goto error;
err = -ENAMETOOLONG;
if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",
x->aalg ? x->aalg->alg_name : "digest_null",
x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
goto error;
aead = crypto_alloc_aead(authenc_name, 0, 0);
err = PTR_ERR(aead);
if (IS_ERR(aead))
goto error;
esp->aead = aead;
keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +
(x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));
err = -ENOMEM;
key = kmalloc(keylen, GFP_KERNEL);
if (!key)
goto error;
p = key;
rta = (void *)p;
rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
rta->rta_len = RTA_LENGTH(sizeof(*param));
param = RTA_DATA(rta);
p += RTA_SPACE(sizeof(*param));
if (x->aalg) {
struct xfrm_algo_desc *aalg_desc;
memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);
p += (x->aalg->alg_key_len + 7) / 8;
aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
BUG_ON(!aalg_desc);
err = -EINVAL;
if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
crypto_aead_authsize(aead)) {
NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
x->aalg->alg_name,
crypto_aead_authsize(aead),
aalg_desc->uinfo.auth.icv_fullbits/8);
goto free_key;
}
err = crypto_aead_setauthsize(
aead, aalg_desc->uinfo.auth.icv_truncbits / 8);
if (err)
goto free_key;
}
param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);
memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);
err = crypto_aead_setkey(aead, key, keylen);
free_key:
kfree(key);
error:
return err;
}
static int esp6_init_state(struct xfrm_state *x)
{
struct esp_data *esp;
struct crypto_aead *aead;
u32 align;
int err;
if (x->encap)
return -EINVAL;
esp = kzalloc(sizeof(*esp), GFP_KERNEL);
if (esp == NULL)
return -ENOMEM;
x->data = esp;
if (x->aead)
err = esp_init_aead(x);
else
err = esp_init_authenc(x);
if (err)
goto error;
aead = esp->aead;
esp->padlen = 0;
x->props.header_len = sizeof(struct ip_esp_hdr) +
crypto_aead_ivsize(aead);
switch (x->props.mode) {
case XFRM_MODE_BEET:
case XFRM_MODE_TRANSPORT:
break;
case XFRM_MODE_TUNNEL:
x->props.header_len += sizeof(struct ipv6hdr);
break;
default:
goto error;
}
align = ALIGN(crypto_aead_blocksize(aead), 4);
if (esp->padlen)
align = max_t(u32, align, esp->padlen);
x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead);
error:
return err;
}
static const 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);