[linux.git] / net / ipv4 / ah4.c

#include <linux/config.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 <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, u32 *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 0x86:	/* Another "Commercial Security" crap. */
		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+2, 0, optlen-2);
		}
		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 = skb->nh.iph;
	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);
	ahp->icv(ahp, skb, ah->auth_data);

	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 xfrm_decap_state *decap, struct sk_buff *skb)
{
	int ah_hlen;
	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 = skb->nh.iph;

	memcpy(work_buf, iph, iph->ihl*4);

	iph->ttl = 0;
	iph->tos = 0;
	iph->frag_off = 0;
	iph->check = 0;
	if (iph->ihl != 5) {
		u32 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, skb->data - skb->nh.raw);
		ahp->icv(ahp, skb, ah->auth_data);
		if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
			x->stats.integrity_failed++;
			goto out;
		}
	}
	((struct iphdr*)work_buf)->protocol = ah->nexthdr;
	skb->nh.raw = skb_pull(skb, ah_hlen);
	memcpy(skb->nh.raw, work_buf, iph->ihl*4);
	skb->nh.iph->tot_len = htons(skb->len);
	skb_pull(skb, skb->nh.iph->ihl*4);
	skb->h.raw = skb->data;

	return 0;

out:
	return -EINVAL;
}

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 (skb->h.icmph->type != ICMP_DEST_UNREACH ||
	    skb->h.icmph->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;

	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 ip_auth_hdr) + ahp->icv_trunc_len);
	if (x->props.mode)
		x->props.header_len += sizeof(struct iphdr);
	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 ah_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 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");
Commit	Line	Data
1da177e4 LT	1	#include <linux/config.h>
	2	#include <linux/module.h>
	3	#include <net/ip.h>
	4	#include <net/xfrm.h>
	5	#include <net/ah.h>
	6	#include <linux/crypto.h>
	7	#include <linux/pfkeyv2.h>
	8	#include <net/icmp.h>
	9	#include <asm/scatterlist.h>
	10
	11
	12	/* Clear mutable options and find final destination to substitute
	13	* into IP header for icv calculation. Options are already checked
	14	* for validity, so paranoia is not required. */
	15
	16	static int ip_clear_mutable_options(struct iphdr iph, u32 daddr)
	17	{
	18	unsigned char * optptr = (unsigned char*)(iph+1);
	19	int l = iph->ihl*4 - sizeof(struct iphdr);
	20	int optlen;
	21
	22	while (l > 0) {
	23	switch (*optptr) {
	24	case IPOPT_END:
	25	return 0;
	26	case IPOPT_NOOP:
	27	l--;
	28	optptr++;
	29	continue;
	30	}
	31	optlen = optptr[1];
	32	if (optlen<2 \|\| optlen>l)
	33	return -EINVAL;
	34	switch (*optptr) {
	35	case IPOPT_SEC:
	36	case 0x85: /* Some "Extended Security" crap. */
	37	case 0x86: /* Another "Commercial Security" crap. */
	38	case IPOPT_RA:
	39	case 0x80\|21: /* RFC1770 */
	40	break;
	41	case IPOPT_LSRR:
	42	case IPOPT_SSRR:
	43	if (optlen < 6)
	44	return -EINVAL;
	45	memcpy(daddr, optptr+optlen-4, 4);
	46	/* Fall through */
	47	default:
	48	memset(optptr+2, 0, optlen-2);
	49	}
	50	l -= optlen;
	51	optptr += optlen;
	52	}
	53	return 0;
	54	}
	55
	56	static int ah_output(struct xfrm_state x, struct sk_buff skb)
	57	{
	58	int err;
	59	struct iphdr iph, top_iph;
	60	struct ip_auth_hdr *ah;
	61	struct ah_data *ahp;
	62	union {
	63	struct iphdr iph;
	64	char buf[60];
65	} tmp_iph;
66
67	top_iph = skb->nh.iph;
68	iph = &tmp_iph.iph;
69
70	iph->tos = top_iph->tos;
71	iph->ttl = top_iph->ttl;
72	iph->frag_off = top_iph->frag_off;
73
74	if (top_iph->ihl != 5) {
75	iph->daddr = top_iph->daddr;
76	memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
77	err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
78	if (err)
79	goto error;
80	}
81
82	ah = (struct ip_auth_hdr )((char )top_iph+top_iph->ihl*4);
83	ah->nexthdr = top_iph->protocol;
84
85	top_iph->tos = 0;
86	top_iph->tot_len = htons(skb->len);
87	top_iph->frag_off = 0;
88	top_iph->ttl = 0;
89	top_iph->protocol = IPPROTO_AH;
90	top_iph->check = 0;
91
92	ahp = x->data;
93	ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
94	ahp->icv_trunc_len) >> 2) - 2;
95
96	ah->reserved = 0;
97	ah->spi = x->id.spi;
98	ah->seq_no = htonl(++x->replay.oseq);
99	ahp->icv(ahp, skb, ah->auth_data);
100
101	top_iph->tos = iph->tos;
102	top_iph->ttl = iph->ttl;
103	top_iph->frag_off = iph->frag_off;
104	if (top_iph->ihl != 5) {
105	top_iph->daddr = iph->daddr;
106	memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
107	}
108
109	ip_send_check(top_iph);
110
111	err = 0;
112
113	error:
114	return err;
115	}
116
117	static int ah_input(struct xfrm_state x, struct xfrm_decap_state decap, struct sk_buff *skb)
118	{
119	int ah_hlen;
120	struct iphdr *iph;
121	struct ip_auth_hdr *ah;
122	struct ah_data *ahp;
123	char work_buf[60];
124
125	if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
126	goto out;
127
128	ah = (struct ip_auth_hdr*)skb->data;
129	ahp = x->data;
130	ah_hlen = (ah->hdrlen + 2) << 2;
131
132	if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) &&
133	ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len))
134	goto out;
135
136	if (!pskb_may_pull(skb, ah_hlen))
137	goto out;
138
139	/* We are going to _remove_ AH header to keep sockets happy,
140	* so... Later this can change. */
141	if (skb_cloned(skb) &&
142	pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
143	goto out;
144
145	skb->ip_summed = CHECKSUM_NONE;
146
147	ah = (struct ip_auth_hdr*)skb->data;
148	iph = skb->nh.iph;
149
150	memcpy(work_buf, iph, iph->ihl*4);
151
152	iph->ttl = 0;
153	iph->tos = 0;
154	iph->frag_off = 0;
155	iph->check = 0;
156	if (iph->ihl != 5) {
157	u32 dummy;
158	if (ip_clear_mutable_options(iph, &dummy))
159	goto out;
160	}
161	{
162	u8 auth_data[MAX_AH_AUTH_LEN];
163
164	memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
165	skb_push(skb, skb->data - skb->nh.raw);
166	ahp->icv(ahp, skb, ah->auth_data);
167	if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
168	x->stats.integrity_failed++;
169	goto out;
170	}
171	}
172	((struct iphdr*)work_buf)->protocol = ah->nexthdr;
173	skb->nh.raw = skb_pull(skb, ah_hlen);
174	memcpy(skb->nh.raw, work_buf, iph->ihl*4);
175	skb->nh.iph->tot_len = htons(skb->len);
176	skb_pull(skb, skb->nh.iph->ihl*4);
177	skb->h.raw = skb->data;
178
179	return 0;
180
181	out:
182	return -EINVAL;
183	}
184
185	static void ah4_err(struct sk_buff *skb, u32 info)
186	{
187	struct iphdr iph = (struct iphdr)skb->data;
188	struct ip_auth_hdr ah = (struct ip_auth_hdr)(skb->data+(iph->ihl<<2));
189	struct xfrm_state *x;
190
191	if (skb->h.icmph->type != ICMP_DEST_UNREACH \|\|
192	skb->h.icmph->code != ICMP_FRAG_NEEDED)
193	return;
194
195	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET);
196	if (!x)
197	return;
198	printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n",
199	ntohl(ah->spi), ntohl(iph->daddr));
200	xfrm_state_put(x);
201	}
202
72cb6962	203	static int ah_init_state(struct xfrm_state *x)
1da177e4 LT	204	{
	205	struct ah_data *ahp = NULL;
	206	struct xfrm_algo_desc *aalg_desc;
	207
	208	if (!x->aalg)
	209	goto error;
	210
	211	/* null auth can use a zero length key */
	212	if (x->aalg->alg_key_len > 512)
	213	goto error;
	214
	215	if (x->encap)
	216	goto error;
	217
	218	ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
	219	if (ahp == NULL)
	220	return -ENOMEM;
	221
	222	memset(ahp, 0, sizeof(*ahp));
	223
	224	ahp->key = x->aalg->alg_key;
	225	ahp->key_len = (x->aalg->alg_key_len+7)/8;
	226	ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
	227	if (!ahp->tfm)
	228	goto error;
	229	ahp->icv = ah_hmac_digest;
	230
	231	/*
	232	* Lookup the algorithm description maintained by xfrm_algo,
	233	* verify crypto transform properties, and store information
	234	* we need for AH processing. This lookup cannot fail here
	235	* after a successful crypto_alloc_tfm().
	236	*/
	237	aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
	238	BUG_ON(!aalg_desc);
	239
	240	if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
	241	crypto_tfm_alg_digestsize(ahp->tfm)) {
	242	printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
	243	x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm),
	244	aalg_desc->uinfo.auth.icv_fullbits/8);
	245	goto error;
	246	}
	247
	248	ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
	249	ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
	250
	251	BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
	252
	253	ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
	254	if (!ahp->work_icv)
	255	goto error;
	256
	257	x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len);
	258	if (x->props.mode)
	259	x->props.header_len += sizeof(struct iphdr);
	260	x->data = ahp;
	261
	262	return 0;
	263
	264	error:
	265	if (ahp) {
	266	if (ahp->work_icv)
	267	kfree(ahp->work_icv);
268	if (ahp->tfm)
269	crypto_free_tfm(ahp->tfm);
270	kfree(ahp);
271	}
272	return -EINVAL;
273	}
274
275	static void ah_destroy(struct xfrm_state *x)
276	{
277	struct ah_data *ahp = x->data;
278
279	if (!ahp)
280	return;
281
282	if (ahp->work_icv) {
283	kfree(ahp->work_icv);
284	ahp->work_icv = NULL;
285	}
286	if (ahp->tfm) {
287	crypto_free_tfm(ahp->tfm);
288	ahp->tfm = NULL;
289	}
290	kfree(ahp);
291	}
292
293
294	static struct xfrm_type ah_type =
295	{
296	.description = "AH4",
297	.owner = THIS_MODULE,
298	.proto = IPPROTO_AH,
299	.init_state = ah_init_state,
300	.destructor = ah_destroy,
301	.input = ah_input,
302	.output = ah_output
303	};
304
305	static struct net_protocol ah4_protocol = {
306	.handler = xfrm4_rcv,
307	.err_handler = ah4_err,
308	.no_policy = 1,
309	};
310
311	static int __init ah4_init(void)
312	{
313	if (xfrm_register_type(&ah_type, AF_INET) < 0) {
314	printk(KERN_INFO "ip ah init: can't add xfrm type\n");
315	return -EAGAIN;
316	}
317	if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
318	printk(KERN_INFO "ip ah init: can't add protocol\n");
319	xfrm_unregister_type(&ah_type, AF_INET);
320	return -EAGAIN;
321	}
322	return 0;
323	}
324
325	static void __exit ah4_fini(void)
326	{
327	if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
328	printk(KERN_INFO "ip ah close: can't remove protocol\n");
329	if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
330	printk(KERN_INFO "ip ah close: can't remove xfrm type\n");
331	}
332
333	module_init(ah4_init);
334	module_exit(ah4_fini);
335	MODULE_LICENSE("GPL");