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NETFILTER: remove unnecessary goto statement for error recovery
[tomato.git] / release / src-rt / linux / linux-2.6 / net / ipv4 / esp4.c
blob392022327d343e0039c1397afcf5b9de86d45f6a
1 #include <linux/err.h>
2 #include <linux/module.h>
3 #include <net/ip.h>
4 #include <net/xfrm.h>
5 #include <net/esp.h>
6 #include <asm/scatterlist.h>
7 #include <linux/crypto.h>
8 #include <linux/kernel.h>
9 #include <linux/pfkeyv2.h>
10 #include <linux/random.h>
11 #include <linux/in6.h>
12 #include <net/icmp.h>
13 #include <net/protocol.h>
14 #include <net/udp.h>
15
16 static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
17 {
18 int err;
19 struct iphdr *top_iph;
20 struct ip_esp_hdr *esph;
21 struct crypto_blkcipher *tfm;
22 struct blkcipher_desc desc;
23 struct esp_data *esp;
24 struct sk_buff *trailer;
25 u8 *tail;
26 int blksize;
27 int clen;
28 int alen;
29 int nfrags;
30
31 /* Strip IP+ESP header. */
32 __skb_pull(skb, skb_transport_offset(skb));
33 /* Now skb is pure payload to encrypt */
34
35 err = -ENOMEM;
36
37 /* Round to block size */
38 clen = skb->len;
39
40 esp = x->data;
41 alen = esp->auth.icv_trunc_len;
42 tfm = esp->conf.tfm;
43 desc.tfm = tfm;
44 desc.flags = 0;
45 blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
46 clen = ALIGN(clen + 2, blksize);
47 if (esp->conf.padlen)
48 clen = ALIGN(clen, esp->conf.padlen);
49
50 if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
51 goto error;
52
53 /* Fill padding... */
54 tail = skb_tail_pointer(trailer);
55 do {
56 int i;
57 for (i=0; i<clen-skb->len - 2; i++)
58 tail[i] = i + 1;
59 } while (0);
60 tail[clen - skb->len - 2] = (clen - skb->len) - 2;
61 pskb_put(skb, trailer, clen - skb->len);
62
63 __skb_push(skb, skb->data - skb_network_header(skb));
64 top_iph = ip_hdr(skb);
65 esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
66 top_iph->ihl * 4);
67 top_iph->tot_len = htons(skb->len + alen);
68 *(skb_tail_pointer(trailer) - 1) = top_iph->protocol;
69
70 /* this is non-NULL only with UDP Encapsulation */
71 if (x->encap) {
72 struct xfrm_encap_tmpl *encap = x->encap;
73 struct udphdr *uh;
74 __be32 *udpdata32;
75
76 uh = (struct udphdr *)esph;
77 uh->source = encap->encap_sport;
78 uh->dest = encap->encap_dport;
79 uh->len = htons(skb->len + alen - top_iph->ihl*4);
80 uh->check = 0;
81
82 switch (encap->encap_type) {
83 default:
84 case UDP_ENCAP_ESPINUDP:
85 esph = (struct ip_esp_hdr *)(uh + 1);
86 break;
87 case UDP_ENCAP_ESPINUDP_NON_IKE:
88 udpdata32 = (__be32 *)(uh + 1);
89 udpdata32[0] = udpdata32[1] = 0;
90 esph = (struct ip_esp_hdr *)(udpdata32 + 2);
91 break;
92 }
93
94 top_iph->protocol = IPPROTO_UDP;
95 } else
96 top_iph->protocol = IPPROTO_ESP;
97
98 esph->spi = x->id.spi;
99 esph->seq_no = htonl(++x->replay.oseq);
100 xfrm_aevent_doreplay(x);
101
102 if (esp->conf.ivlen) {
103 if (unlikely(!esp->conf.ivinitted)) {
104 get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
105 esp->conf.ivinitted = 1;
106 }
107 crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
108 }
109
110 do {
111 struct scatterlist *sg = &esp->sgbuf[0];
112
113 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
114 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
115 if (!sg)
116 goto error;
117 }
118 skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
119 err = crypto_blkcipher_encrypt(&desc, sg, sg, clen);
120 if (unlikely(sg != &esp->sgbuf[0]))
121 kfree(sg);
122 } while (0);
123
124 if (unlikely(err))
125 goto error;
126
127 if (esp->conf.ivlen) {
128 memcpy(esph->enc_data, esp->conf.ivec, esp->conf.ivlen);
129 crypto_blkcipher_get_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
130 }
131
132 if (esp->auth.icv_full_len) {
133 err = esp_mac_digest(esp, skb, (u8 *)esph - skb->data,
134 sizeof(*esph) + esp->conf.ivlen + clen);
135 memcpy(pskb_put(skb, trailer, alen), esp->auth.work_icv, alen);
136 }
137
138 ip_send_check(top_iph);
139
140 error:
141 return err;
142 }
143
144 /*
145 * Note: detecting truncated vs. non-truncated authentication data is very
146 * expensive, so we only support truncated data, which is the recommended
147 * and common case.
148 */
149 static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
150 {
151 struct iphdr *iph;
152 struct ip_esp_hdr *esph;
153 struct esp_data *esp = x->data;
154 struct crypto_blkcipher *tfm = esp->conf.tfm;
155 struct blkcipher_desc desc = { .tfm = tfm };
156 struct sk_buff *trailer;
157 int blksize = ALIGN(crypto_blkcipher_blocksize(tfm), 4);
158 int alen = esp->auth.icv_trunc_len;
159 int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
160 int nfrags;
161 int ihl;
162 u8 nexthdr[2];
163 struct scatterlist *sg;
164 int padlen;
165 int err;
166
167 if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
168 goto out;
169
170 if (elen <= 0 || (elen & (blksize-1)))
171 goto out;
172
173 /* If integrity check is required, do this. */
174 if (esp->auth.icv_full_len) {
175 u8 sum[alen];
176
177 err = esp_mac_digest(esp, skb, 0, skb->len - alen);
178 if (err)
179 goto out;
180
181 if (skb_copy_bits(skb, skb->len - alen, sum, alen))
182 BUG();
183
184 if (unlikely(memcmp(esp->auth.work_icv, sum, alen))) {
185 x->stats.integrity_failed++;
186 goto out;
187 }
188 }
189
190 if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
191 goto out;
192
193 skb->ip_summed = CHECKSUM_NONE;
194
195 esph = (struct ip_esp_hdr*)skb->data;
196
197 /* Get ivec. This can be wrong, check against another impls. */
198 if (esp->conf.ivlen)
199 crypto_blkcipher_set_iv(tfm, esph->enc_data, esp->conf.ivlen);
200
201 sg = &esp->sgbuf[0];
202
203 if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
204 sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
205 if (!sg)
206 goto out;
207 }
208 skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
209 err = crypto_blkcipher_decrypt(&desc, sg, sg, elen);
210 if (unlikely(sg != &esp->sgbuf[0]))
211 kfree(sg);
212 if (unlikely(err))
213 return err;
214
215 if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
216 BUG();
217
218 padlen = nexthdr[0];
219 if (padlen+2 >= elen)
220 goto out;
221
222 /* ... check padding bits here. Silly. :-) */
223
224 /* RFC4303: Drop dummy packets without any error */
225 if (nexthdr[1] == IPPROTO_NONE)
226 goto out;
227
228 iph = ip_hdr(skb);
229 ihl = iph->ihl * 4;
230
231 if (x->encap) {
232 struct xfrm_encap_tmpl *encap = x->encap;
233 struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
234
235 /*
236 * 1) if the NAT-T peer's IP or port changed then
237 * advertize the change to the keying daemon.
238 * This is an inbound SA, so just compare
239 * SRC ports.
240 */
241 if (iph->saddr != x->props.saddr.a4 ||
242 uh->source != encap->encap_sport) {
243 xfrm_address_t ipaddr;
244
245 ipaddr.a4 = iph->saddr;
246 km_new_mapping(x, &ipaddr, uh->source);
247
248 /* XXX: perhaps add an extra
249 * policy check here, to see
250 * if we should allow or
251 * reject a packet from a
252 * different source
253 * address/port.
254 */
255 }
256
257 /*
258 * 2) ignore UDP/TCP checksums in case
259 * of NAT-T in Transport Mode, or
260 * perform other post-processing fixes
261 * as per draft-ietf-ipsec-udp-encaps-06,
262 * section 3.1.2
263 */
264 if (x->props.mode == XFRM_MODE_TRANSPORT ||
265 x->props.mode == XFRM_MODE_BEET)
266 skb->ip_summed = CHECKSUM_UNNECESSARY;
267 }
268
269 iph->protocol = nexthdr[1];
270 pskb_trim(skb, skb->len - alen - padlen - 2);
271 __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen);
272 skb_set_transport_header(skb, -ihl);
273
274 return 0;
275
276 out:
277 return -EINVAL;
278 }
279
280 static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
281 {
282 struct esp_data *esp = x->data;
283 u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
284 u32 align = max_t(u32, blksize, esp->conf.padlen);
285 u32 rem;
286
287 mtu -= x->props.header_len + esp->auth.icv_trunc_len;
288 rem = mtu & (align - 1);
289 mtu &= ~(align - 1);
290
291 switch (x->props.mode) {
292 case XFRM_MODE_TUNNEL:
293 break;
294 default:
295 case XFRM_MODE_TRANSPORT:
296 /* The worst case */
297 mtu -= blksize - 4;
298 mtu += min_t(u32, blksize - 4, rem);
299 break;
300 case XFRM_MODE_BEET:
301 /* The worst case. */
302 mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
303 break;
304 }
305
306 return mtu - 2;
307 }
308
309 static void esp4_err(struct sk_buff *skb, u32 info)
310 {
311 struct iphdr *iph = (struct iphdr*)skb->data;
312 struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2));
313 struct xfrm_state *x;
314
315 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
316 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
317 return;
318
319 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
320 if (!x)
321 return;
322 NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
323 ntohl(esph->spi), ntohl(iph->daddr));
324 xfrm_state_put(x);
325 }
326
327 static void esp_destroy(struct xfrm_state *x)
328 {
329 struct esp_data *esp = x->data;
330
331 if (!esp)
332 return;
333
334 crypto_free_blkcipher(esp->conf.tfm);
335 esp->conf.tfm = NULL;
336 kfree(esp->conf.ivec);
337 esp->conf.ivec = NULL;
338 crypto_free_hash(esp->auth.tfm);
339 esp->auth.tfm = NULL;
340 kfree(esp->auth.work_icv);
341 esp->auth.work_icv = NULL;
342 kfree(esp);
343 }
344
345 static int esp_init_state(struct xfrm_state *x)
346 {
347 struct esp_data *esp = NULL;
348 struct crypto_blkcipher *tfm;
349 u32 align;
350
351 /* null auth and encryption can have zero length keys */
352 if (x->aalg) {
353 if (x->aalg->alg_key_len > 512)
354 goto error;
355 }
356 if (x->ealg == NULL)
357 goto error;
358
359 esp = kzalloc(sizeof(*esp), GFP_KERNEL);
360 if (esp == NULL)
361 return -ENOMEM;
362
363 if (x->aalg) {
364 struct xfrm_algo_desc *aalg_desc;
365 struct crypto_hash *hash;
366
367 esp->auth.key = x->aalg->alg_key;
368 esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
369 hash = crypto_alloc_hash(x->aalg->alg_name, 0,
370 CRYPTO_ALG_ASYNC);
371 if (IS_ERR(hash))
372 goto error;
373
374 esp->auth.tfm = hash;
375 if (crypto_hash_setkey(hash, esp->auth.key, esp->auth.key_len))
376 goto error;
377
378 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
379 BUG_ON(!aalg_desc);
380
381 if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
382 crypto_hash_digestsize(hash)) {
383 NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
384 x->aalg->alg_name,
385 crypto_hash_digestsize(hash),
386 aalg_desc->uinfo.auth.icv_fullbits/8);
387 goto error;
388 }
389
390 esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
391 esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
392
393 esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
394 if (!esp->auth.work_icv)
395 goto error;
396 }
397 esp->conf.key = x->ealg->alg_key;
398 esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
399 tfm = crypto_alloc_blkcipher(x->ealg->alg_name, 0, CRYPTO_ALG_ASYNC);
400 if (IS_ERR(tfm))
401 goto error;
402 esp->conf.tfm = tfm;
403 esp->conf.ivlen = crypto_blkcipher_ivsize(tfm);
404 esp->conf.padlen = 0;
405 if (esp->conf.ivlen) {
406 esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
407 if (unlikely(esp->conf.ivec == NULL))
408 goto error;
409 esp->conf.ivinitted = 0;
410 }
411 if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
412 goto error;
413 x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
414 if (x->props.mode == XFRM_MODE_TUNNEL)
415 x->props.header_len += sizeof(struct iphdr);
416 else if (x->props.mode == XFRM_MODE_BEET)
417 x->props.header_len += IPV4_BEET_PHMAXLEN;
418 if (x->encap) {
419 struct xfrm_encap_tmpl *encap = x->encap;
420
421 switch (encap->encap_type) {
422 default:
423 goto error;
424 case UDP_ENCAP_ESPINUDP:
425 x->props.header_len += sizeof(struct udphdr);
426 break;
427 case UDP_ENCAP_ESPINUDP_NON_IKE:
428 x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
429 break;
430 }
431 }
432 x->data = esp;
433 align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
434 if (esp->conf.padlen)
435 align = max_t(u32, align, esp->conf.padlen);
436 x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len;
437 return 0;
438
439 error:
440 x->data = esp;
441 esp_destroy(x);
442 x->data = NULL;
443 return -EINVAL;
444 }
445
446 static struct xfrm_type esp_type =
447 {
448 .description = "ESP4",
449 .owner = THIS_MODULE,
450 .proto = IPPROTO_ESP,
451 .init_state = esp_init_state,
452 .destructor = esp_destroy,
453 .get_mtu = esp4_get_mtu,
454 .input = esp_input,
455 .output = esp_output
456 };
457
458 static struct net_protocol esp4_protocol = {
459 .handler = xfrm4_rcv,
460 .err_handler = esp4_err,
461 .no_policy = 1,
462 };
463
464 static int __init esp4_init(void)
465 {
466 if (xfrm_register_type(&esp_type, AF_INET) < 0) {
467 printk(KERN_INFO "ip esp init: can't add xfrm type\n");
468 return -EAGAIN;
469 }
470 if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) {
471 printk(KERN_INFO "ip esp init: can't add protocol\n");
472 xfrm_unregister_type(&esp_type, AF_INET);
473 return -EAGAIN;
474 }
475 return 0;
476 }
477
478 static void __exit esp4_fini(void)
479 {
480 if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
481 printk(KERN_INFO "ip esp close: can't remove protocol\n");
482 if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
483 printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
484 }
485
486 module_init(esp4_init);
487 module_exit(esp4_fini);
488 MODULE_LICENSE("GPL");
Tomato firmware and modifications.