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/esp.h> | |
6 | #include <asm/scatterlist.h> | |
7 | #include <linux/crypto.h> | |
8 | #include <linux/pfkeyv2.h> | |
9 | #include <linux/random.h> | |
10 | #include <net/icmp.h> | |
11 | #include <net/udp.h> | |
12 | ||
13 | /* decapsulation data for use when post-processing */ | |
14 | struct esp_decap_data { | |
15 | xfrm_address_t saddr; | |
16 | __u16 sport; | |
17 | __u8 proto; | |
18 | }; | |
19 | ||
20 | static int esp_output(struct xfrm_state *x, struct sk_buff *skb) | |
21 | { | |
22 | int err; | |
23 | struct iphdr *top_iph; | |
24 | struct ip_esp_hdr *esph; | |
25 | struct crypto_tfm *tfm; | |
26 | struct esp_data *esp; | |
27 | struct sk_buff *trailer; | |
28 | int blksize; | |
29 | int clen; | |
30 | int alen; | |
31 | int nfrags; | |
32 | ||
33 | /* Strip IP+ESP header. */ | |
34 | __skb_pull(skb, skb->h.raw - skb->data); | |
35 | /* Now skb is pure payload to encrypt */ | |
36 | ||
37 | err = -ENOMEM; | |
38 | ||
39 | /* Round to block size */ | |
40 | clen = skb->len; | |
41 | ||
42 | esp = x->data; | |
43 | alen = esp->auth.icv_trunc_len; | |
44 | tfm = esp->conf.tfm; | |
45 | blksize = (crypto_tfm_alg_blocksize(tfm) + 3) & ~3; | |
46 | clen = (clen + 2 + blksize-1)&~(blksize-1); | |
47 | if (esp->conf.padlen) | |
48 | clen = (clen + esp->conf.padlen-1)&~(esp->conf.padlen-1); | |
49 | ||
50 | if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0) | |
51 | goto error; | |
52 | ||
53 | /* Fill padding... */ | |
54 | do { | |
55 | int i; | |
56 | for (i=0; i<clen-skb->len - 2; i++) | |
57 | *(u8*)(trailer->tail + i) = i+1; | |
58 | } while (0); | |
59 | *(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2; | |
60 | pskb_put(skb, trailer, clen - skb->len); | |
61 | ||
62 | __skb_push(skb, skb->data - skb->nh.raw); | |
63 | top_iph = skb->nh.iph; | |
64 | esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4); | |
65 | top_iph->tot_len = htons(skb->len + alen); | |
66 | *(u8*)(trailer->tail - 1) = top_iph->protocol; | |
67 | ||
68 | /* this is non-NULL only with UDP Encapsulation */ | |
69 | if (x->encap) { | |
70 | struct xfrm_encap_tmpl *encap = x->encap; | |
71 | struct udphdr *uh; | |
72 | u32 *udpdata32; | |
73 | ||
74 | uh = (struct udphdr *)esph; | |
75 | uh->source = encap->encap_sport; | |
76 | uh->dest = encap->encap_dport; | |
77 | uh->len = htons(skb->len + alen - top_iph->ihl*4); | |
78 | uh->check = 0; | |
79 | ||
80 | switch (encap->encap_type) { | |
81 | default: | |
82 | case UDP_ENCAP_ESPINUDP: | |
83 | esph = (struct ip_esp_hdr *)(uh + 1); | |
84 | break; | |
85 | case UDP_ENCAP_ESPINUDP_NON_IKE: | |
86 | udpdata32 = (u32 *)(uh + 1); | |
87 | udpdata32[0] = udpdata32[1] = 0; | |
88 | esph = (struct ip_esp_hdr *)(udpdata32 + 2); | |
89 | break; | |
90 | } | |
91 | ||
92 | top_iph->protocol = IPPROTO_UDP; | |
93 | } else | |
94 | top_iph->protocol = IPPROTO_ESP; | |
95 | ||
96 | esph->spi = x->id.spi; | |
97 | esph->seq_no = htonl(++x->replay.oseq); | |
98 | ||
99 | if (esp->conf.ivlen) | |
100 | crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); | |
101 | ||
102 | do { | |
103 | struct scatterlist *sg = &esp->sgbuf[0]; | |
104 | ||
105 | if (unlikely(nfrags > ESP_NUM_FAST_SG)) { | |
106 | sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); | |
107 | if (!sg) | |
108 | goto error; | |
109 | } | |
110 | skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen); | |
111 | crypto_cipher_encrypt(tfm, sg, sg, clen); | |
112 | if (unlikely(sg != &esp->sgbuf[0])) | |
113 | kfree(sg); | |
114 | } while (0); | |
115 | ||
116 | if (esp->conf.ivlen) { | |
117 | memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); | |
118 | crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm)); | |
119 | } | |
120 | ||
121 | if (esp->auth.icv_full_len) { | |
122 | esp->auth.icv(esp, skb, (u8*)esph-skb->data, | |
123 | sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail); | |
124 | pskb_put(skb, trailer, alen); | |
125 | } | |
126 | ||
127 | ip_send_check(top_iph); | |
128 | ||
129 | err = 0; | |
130 | ||
131 | error: | |
132 | return err; | |
133 | } | |
134 | ||
135 | /* | |
136 | * Note: detecting truncated vs. non-truncated authentication data is very | |
137 | * expensive, so we only support truncated data, which is the recommended | |
138 | * and common case. | |
139 | */ | |
140 | static int esp_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) | |
141 | { | |
142 | struct iphdr *iph; | |
143 | struct ip_esp_hdr *esph; | |
144 | struct esp_data *esp = x->data; | |
145 | struct sk_buff *trailer; | |
146 | int blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); | |
147 | int alen = esp->auth.icv_trunc_len; | |
148 | int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; | |
149 | int nfrags; | |
150 | int encap_len = 0; | |
151 | ||
152 | if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr))) | |
153 | goto out; | |
154 | ||
155 | if (elen <= 0 || (elen & (blksize-1))) | |
156 | goto out; | |
157 | ||
158 | /* If integrity check is required, do this. */ | |
159 | if (esp->auth.icv_full_len) { | |
160 | u8 sum[esp->auth.icv_full_len]; | |
161 | u8 sum1[alen]; | |
162 | ||
163 | esp->auth.icv(esp, skb, 0, skb->len-alen, sum); | |
164 | ||
165 | if (skb_copy_bits(skb, skb->len-alen, sum1, alen)) | |
166 | BUG(); | |
167 | ||
168 | if (unlikely(memcmp(sum, sum1, alen))) { | |
169 | x->stats.integrity_failed++; | |
170 | goto out; | |
171 | } | |
172 | } | |
173 | ||
174 | if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) | |
175 | goto out; | |
176 | ||
177 | skb->ip_summed = CHECKSUM_NONE; | |
178 | ||
179 | esph = (struct ip_esp_hdr*)skb->data; | |
180 | iph = skb->nh.iph; | |
181 | ||
182 | /* Get ivec. This can be wrong, check against another impls. */ | |
183 | if (esp->conf.ivlen) | |
184 | crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm)); | |
185 | ||
186 | { | |
187 | u8 nexthdr[2]; | |
188 | struct scatterlist *sg = &esp->sgbuf[0]; | |
189 | u8 workbuf[60]; | |
190 | int padlen; | |
191 | ||
192 | if (unlikely(nfrags > ESP_NUM_FAST_SG)) { | |
193 | sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC); | |
194 | if (!sg) | |
195 | goto out; | |
196 | } | |
197 | skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen); | |
198 | crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen); | |
199 | if (unlikely(sg != &esp->sgbuf[0])) | |
200 | kfree(sg); | |
201 | ||
202 | if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2)) | |
203 | BUG(); | |
204 | ||
205 | padlen = nexthdr[0]; | |
206 | if (padlen+2 >= elen) | |
207 | goto out; | |
208 | ||
209 | /* ... check padding bits here. Silly. :-) */ | |
210 | ||
211 | if (x->encap && decap && decap->decap_type) { | |
212 | struct esp_decap_data *encap_data; | |
213 | struct udphdr *uh = (struct udphdr *) (iph+1); | |
214 | ||
215 | encap_data = (struct esp_decap_data *) (decap->decap_data); | |
216 | encap_data->proto = 0; | |
217 | ||
218 | switch (decap->decap_type) { | |
219 | case UDP_ENCAP_ESPINUDP: | |
220 | case UDP_ENCAP_ESPINUDP_NON_IKE: | |
221 | encap_data->proto = AF_INET; | |
222 | encap_data->saddr.a4 = iph->saddr; | |
223 | encap_data->sport = uh->source; | |
224 | encap_len = (void*)esph - (void*)uh; | |
225 | break; | |
226 | ||
227 | default: | |
228 | goto out; | |
229 | } | |
230 | } | |
231 | ||
232 | iph->protocol = nexthdr[1]; | |
233 | pskb_trim(skb, skb->len - alen - padlen - 2); | |
234 | memcpy(workbuf, skb->nh.raw, iph->ihl*4); | |
235 | skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen); | |
236 | skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen; | |
237 | memcpy(skb->nh.raw, workbuf, iph->ihl*4); | |
238 | skb->nh.iph->tot_len = htons(skb->len); | |
239 | } | |
240 | ||
241 | return 0; | |
242 | ||
243 | out: | |
244 | return -EINVAL; | |
245 | } | |
246 | ||
247 | static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) | |
248 | { | |
249 | ||
250 | if (x->encap) { | |
251 | struct xfrm_encap_tmpl *encap; | |
252 | struct esp_decap_data *decap_data; | |
253 | ||
254 | encap = x->encap; | |
255 | decap_data = (struct esp_decap_data *)(decap->decap_data); | |
256 | ||
257 | /* first, make sure that the decap type == the encap type */ | |
258 | if (encap->encap_type != decap->decap_type) | |
259 | return -EINVAL; | |
260 | ||
261 | switch (encap->encap_type) { | |
262 | default: | |
263 | case UDP_ENCAP_ESPINUDP: | |
264 | case UDP_ENCAP_ESPINUDP_NON_IKE: | |
265 | /* | |
266 | * 1) if the NAT-T peer's IP or port changed then | |
267 | * advertize the change to the keying daemon. | |
268 | * This is an inbound SA, so just compare | |
269 | * SRC ports. | |
270 | */ | |
271 | if (decap_data->proto == AF_INET && | |
272 | (decap_data->saddr.a4 != x->props.saddr.a4 || | |
273 | decap_data->sport != encap->encap_sport)) { | |
274 | xfrm_address_t ipaddr; | |
275 | ||
276 | ipaddr.a4 = decap_data->saddr.a4; | |
277 | km_new_mapping(x, &ipaddr, decap_data->sport); | |
278 | ||
279 | /* XXX: perhaps add an extra | |
280 | * policy check here, to see | |
281 | * if we should allow or | |
282 | * reject a packet from a | |
283 | * different source | |
284 | * address/port. | |
285 | */ | |
286 | } | |
287 | ||
288 | /* | |
289 | * 2) ignore UDP/TCP checksums in case | |
290 | * of NAT-T in Transport Mode, or | |
291 | * perform other post-processing fixes | |
292 | * as per * draft-ietf-ipsec-udp-encaps-06, | |
293 | * section 3.1.2 | |
294 | */ | |
295 | if (!x->props.mode) | |
296 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
297 | ||
298 | break; | |
299 | } | |
300 | } | |
301 | return 0; | |
302 | } | |
303 | ||
304 | static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) | |
305 | { | |
306 | struct esp_data *esp = x->data; | |
307 | u32 blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); | |
308 | ||
309 | if (x->props.mode) { | |
310 | mtu = (mtu + 2 + blksize-1)&~(blksize-1); | |
311 | } else { | |
312 | /* The worst case. */ | |
313 | mtu += 2 + blksize; | |
314 | } | |
315 | if (esp->conf.padlen) | |
316 | mtu = (mtu + esp->conf.padlen-1)&~(esp->conf.padlen-1); | |
317 | ||
318 | return mtu + x->props.header_len + esp->auth.icv_trunc_len; | |
319 | } | |
320 | ||
321 | static void esp4_err(struct sk_buff *skb, u32 info) | |
322 | { | |
323 | struct iphdr *iph = (struct iphdr*)skb->data; | |
324 | struct ip_esp_hdr *esph = (struct ip_esp_hdr*)(skb->data+(iph->ihl<<2)); | |
325 | struct xfrm_state *x; | |
326 | ||
327 | if (skb->h.icmph->type != ICMP_DEST_UNREACH || | |
328 | skb->h.icmph->code != ICMP_FRAG_NEEDED) | |
329 | return; | |
330 | ||
331 | x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET); | |
332 | if (!x) | |
333 | return; | |
334 | NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n", | |
335 | ntohl(esph->spi), ntohl(iph->daddr))); | |
336 | xfrm_state_put(x); | |
337 | } | |
338 | ||
339 | static void esp_destroy(struct xfrm_state *x) | |
340 | { | |
341 | struct esp_data *esp = x->data; | |
342 | ||
343 | if (!esp) | |
344 | return; | |
345 | ||
346 | if (esp->conf.tfm) { | |
347 | crypto_free_tfm(esp->conf.tfm); | |
348 | esp->conf.tfm = NULL; | |
349 | } | |
350 | if (esp->conf.ivec) { | |
351 | kfree(esp->conf.ivec); | |
352 | esp->conf.ivec = NULL; | |
353 | } | |
354 | if (esp->auth.tfm) { | |
355 | crypto_free_tfm(esp->auth.tfm); | |
356 | esp->auth.tfm = NULL; | |
357 | } | |
358 | if (esp->auth.work_icv) { | |
359 | kfree(esp->auth.work_icv); | |
360 | esp->auth.work_icv = NULL; | |
361 | } | |
362 | kfree(esp); | |
363 | } | |
364 | ||
72cb6962 | 365 | static int esp_init_state(struct xfrm_state *x) |
1da177e4 LT |
366 | { |
367 | struct esp_data *esp = NULL; | |
368 | ||
369 | /* null auth and encryption can have zero length keys */ | |
370 | if (x->aalg) { | |
371 | if (x->aalg->alg_key_len > 512) | |
372 | goto error; | |
373 | } | |
374 | if (x->ealg == NULL) | |
375 | goto error; | |
376 | ||
377 | esp = kmalloc(sizeof(*esp), GFP_KERNEL); | |
378 | if (esp == NULL) | |
379 | return -ENOMEM; | |
380 | ||
381 | memset(esp, 0, sizeof(*esp)); | |
382 | ||
383 | if (x->aalg) { | |
384 | struct xfrm_algo_desc *aalg_desc; | |
385 | ||
386 | esp->auth.key = x->aalg->alg_key; | |
387 | esp->auth.key_len = (x->aalg->alg_key_len+7)/8; | |
388 | esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); | |
389 | if (esp->auth.tfm == NULL) | |
390 | goto error; | |
391 | esp->auth.icv = esp_hmac_digest; | |
392 | ||
393 | aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); | |
394 | BUG_ON(!aalg_desc); | |
395 | ||
396 | if (aalg_desc->uinfo.auth.icv_fullbits/8 != | |
397 | crypto_tfm_alg_digestsize(esp->auth.tfm)) { | |
398 | NETDEBUG(printk(KERN_INFO "ESP: %s digestsize %u != %hu\n", | |
399 | x->aalg->alg_name, | |
400 | crypto_tfm_alg_digestsize(esp->auth.tfm), | |
401 | aalg_desc->uinfo.auth.icv_fullbits/8)); | |
402 | goto error; | |
403 | } | |
404 | ||
405 | esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; | |
406 | esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; | |
407 | ||
408 | esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL); | |
409 | if (!esp->auth.work_icv) | |
410 | goto error; | |
411 | } | |
412 | esp->conf.key = x->ealg->alg_key; | |
413 | esp->conf.key_len = (x->ealg->alg_key_len+7)/8; | |
414 | if (x->props.ealgo == SADB_EALG_NULL) | |
415 | esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB); | |
416 | else | |
417 | esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC); | |
418 | if (esp->conf.tfm == NULL) | |
419 | goto error; | |
420 | esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm); | |
421 | esp->conf.padlen = 0; | |
422 | if (esp->conf.ivlen) { | |
423 | esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL); | |
424 | if (unlikely(esp->conf.ivec == NULL)) | |
425 | goto error; | |
426 | get_random_bytes(esp->conf.ivec, esp->conf.ivlen); | |
427 | } | |
428 | if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len)) | |
429 | goto error; | |
430 | x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen; | |
431 | if (x->props.mode) | |
432 | x->props.header_len += sizeof(struct iphdr); | |
433 | if (x->encap) { | |
434 | struct xfrm_encap_tmpl *encap = x->encap; | |
435 | ||
436 | switch (encap->encap_type) { | |
437 | default: | |
438 | goto error; | |
439 | case UDP_ENCAP_ESPINUDP: | |
440 | x->props.header_len += sizeof(struct udphdr); | |
441 | break; | |
442 | case UDP_ENCAP_ESPINUDP_NON_IKE: | |
443 | x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32); | |
444 | break; | |
445 | } | |
446 | } | |
447 | x->data = esp; | |
448 | x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len; | |
449 | return 0; | |
450 | ||
451 | error: | |
452 | x->data = esp; | |
453 | esp_destroy(x); | |
454 | x->data = NULL; | |
455 | return -EINVAL; | |
456 | } | |
457 | ||
458 | static struct xfrm_type esp_type = | |
459 | { | |
460 | .description = "ESP4", | |
461 | .owner = THIS_MODULE, | |
462 | .proto = IPPROTO_ESP, | |
463 | .init_state = esp_init_state, | |
464 | .destructor = esp_destroy, | |
465 | .get_max_size = esp4_get_max_size, | |
466 | .input = esp_input, | |
467 | .post_input = esp_post_input, | |
468 | .output = esp_output | |
469 | }; | |
470 | ||
471 | static struct net_protocol esp4_protocol = { | |
472 | .handler = xfrm4_rcv, | |
473 | .err_handler = esp4_err, | |
474 | .no_policy = 1, | |
475 | }; | |
476 | ||
477 | static int __init esp4_init(void) | |
478 | { | |
479 | struct xfrm_decap_state decap; | |
480 | ||
36839836 | 481 | if (sizeof(struct esp_decap_data) > |
1da177e4 LT |
482 | sizeof(decap.decap_data)) { |
483 | extern void decap_data_too_small(void); | |
484 | ||
485 | decap_data_too_small(); | |
486 | } | |
487 | ||
488 | if (xfrm_register_type(&esp_type, AF_INET) < 0) { | |
489 | printk(KERN_INFO "ip esp init: can't add xfrm type\n"); | |
490 | return -EAGAIN; | |
491 | } | |
492 | if (inet_add_protocol(&esp4_protocol, IPPROTO_ESP) < 0) { | |
493 | printk(KERN_INFO "ip esp init: can't add protocol\n"); | |
494 | xfrm_unregister_type(&esp_type, AF_INET); | |
495 | return -EAGAIN; | |
496 | } | |
497 | return 0; | |
498 | } | |
499 | ||
500 | static void __exit esp4_fini(void) | |
501 | { | |
502 | if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0) | |
503 | printk(KERN_INFO "ip esp close: can't remove protocol\n"); | |
504 | if (xfrm_unregister_type(&esp_type, AF_INET) < 0) | |
505 | printk(KERN_INFO "ip esp close: can't remove xfrm type\n"); | |
506 | } | |
507 | ||
508 | module_init(esp4_init); | |
509 | module_exit(esp4_fini); | |
510 | MODULE_LICENSE("GPL"); |