android_kernel_xiaomi_sm8350/net/ipv4/ah4.c
Nick Bowler 96fe1c0237 [IPSEC] AH4: Update IPv4 options handling to conform to RFC 4302.
In testing our ESP/AH offload hardware, I discovered an issue with how
AH handles mutable fields in IPv4.  RFC 4302 (AH) states the following
on the subject:

        For IPv4, the entire option is viewed as a unit; so even
        though the type and length fields within most options are immutable
        in transit, if an option is classified as mutable, the entire option
        is zeroed for ICV computation purposes.

The current implementation does not zero the type and length fields,
resulting in authentication failures when communicating with hosts
that do (i.e. FreeBSD).

I have tested record route and timestamp options (ping -R and ping -T)
on a small network involving Windows XP, FreeBSD 6.2, and Linux hosts,
with one router.  In the presence of these options, the FreeBSD and
Linux hosts (with the patch or with the hardware) can communicate.
The Windows XP host simply fails to accept these packets with or
without the patch.

I have also been trying to test source routing options (using
traceroute -g), but haven't had much luck getting this option to work
*without* AH, let alone with.

Signed-off-by: Nick Bowler <nbowler@ellipticsemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-08-26 18:35:33 -07:00

343 lines
7.7 KiB
C

#include <linux/err.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, __be32 *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 IPOPT_CIPSO:
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, 0, optlen);
}
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 = ip_hdr(skb);
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);
err = ah_mac_digest(ahp, skb, ah->auth_data);
if (err)
goto error;
memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len);
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;
int err = -EINVAL;
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 = ip_hdr(skb);
ihl = skb->data - skb_network_header(skb);
memcpy(work_buf, iph, ihl);
iph->ttl = 0;
iph->tos = 0;
iph->frag_off = 0;
iph->check = 0;
if (ihl > sizeof(*iph)) {
__be32 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);
err = ah_mac_digest(ahp, skb, ah->auth_data);
if (err)
goto out;
err = -EINVAL;
if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) {
x->stats.integrity_failed++;
goto out;
}
}
((struct iphdr*)work_buf)->protocol = ah->nexthdr;
skb->network_header += ah_hlen;
memcpy(skb_network_header(skb), work_buf, ihl);
skb->transport_header = skb->network_header;
__skb_pull(skb, ah_hlen + ihl);
return 0;
out:
return err;
}
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 (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
icmp_hdr(skb)->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;
struct crypto_hash *tfm;
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;
tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
goto error;
ahp->tfm = tfm;
if (crypto_hash_setkey(tfm, ahp->key, ahp->key_len))
goto error;
/*
* 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_hash().
*/
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(tfm)) {
printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
x->aalg->alg_name, crypto_hash_digestsize(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 == XFRM_MODE_TUNNEL)
x->props.header_len += sizeof(struct iphdr);
x->data = ahp;
return 0;
error:
if (ahp) {
kfree(ahp->work_icv);
crypto_free_hash(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_hash(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");
MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);