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1da177e4 LT |
1 | /* |
2 | * Copyright (C)2002 USAGI/WIDE Project | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
17 | * | |
18 | * Authors | |
19 | * | |
20 | * Mitsuru KANDA @USAGI : IPv6 Support | |
21 | * Kazunori MIYAZAWA @USAGI : | |
22 | * Kunihiro Ishiguro <kunihiro@ipinfusion.com> | |
23 | * | |
24 | * This file is derived from net/ipv4/ah.c. | |
25 | */ | |
26 | ||
27 | #include <linux/config.h> | |
28 | #include <linux/module.h> | |
29 | #include <net/ip.h> | |
30 | #include <net/ah.h> | |
31 | #include <linux/crypto.h> | |
32 | #include <linux/pfkeyv2.h> | |
33 | #include <linux/string.h> | |
34 | #include <net/icmp.h> | |
35 | #include <net/ipv6.h> | |
36 | #include <net/xfrm.h> | |
37 | #include <asm/scatterlist.h> | |
38 | ||
39 | static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr) | |
40 | { | |
41 | u8 *opt = (u8 *)opthdr; | |
42 | int len = ipv6_optlen(opthdr); | |
43 | int off = 0; | |
44 | int optlen = 0; | |
45 | ||
46 | off += 2; | |
47 | len -= 2; | |
48 | ||
49 | while (len > 0) { | |
50 | ||
51 | switch (opt[off]) { | |
52 | ||
53 | case IPV6_TLV_PAD0: | |
54 | optlen = 1; | |
55 | break; | |
56 | default: | |
57 | if (len < 2) | |
58 | goto bad; | |
59 | optlen = opt[off+1]+2; | |
60 | if (len < optlen) | |
61 | goto bad; | |
62 | if (opt[off] & 0x20) | |
63 | memset(&opt[off+2], 0, opt[off+1]); | |
64 | break; | |
65 | } | |
66 | ||
67 | off += optlen; | |
68 | len -= optlen; | |
69 | } | |
70 | if (len == 0) | |
71 | return 1; | |
72 | ||
73 | bad: | |
74 | return 0; | |
75 | } | |
76 | ||
77 | /** | |
78 | * ipv6_rearrange_rthdr - rearrange IPv6 routing header | |
79 | * @iph: IPv6 header | |
80 | * @rthdr: routing header | |
81 | * | |
82 | * Rearrange the destination address in @iph and the addresses in @rthdr | |
83 | * so that they appear in the order they will at the final destination. | |
84 | * See Appendix A2 of RFC 2402 for details. | |
85 | */ | |
86 | static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr) | |
87 | { | |
88 | int segments, segments_left; | |
89 | struct in6_addr *addrs; | |
90 | struct in6_addr final_addr; | |
91 | ||
92 | segments_left = rthdr->segments_left; | |
93 | if (segments_left == 0) | |
94 | return; | |
95 | rthdr->segments_left = 0; | |
96 | ||
97 | /* The value of rthdr->hdrlen has been verified either by the system | |
98 | * call if it is locally generated, or by ipv6_rthdr_rcv() for incoming | |
99 | * packets. So we can assume that it is even and that segments is | |
100 | * greater than or equal to segments_left. | |
101 | * | |
102 | * For the same reason we can assume that this option is of type 0. | |
103 | */ | |
104 | segments = rthdr->hdrlen >> 1; | |
105 | ||
106 | addrs = ((struct rt0_hdr *)rthdr)->addr; | |
107 | ipv6_addr_copy(&final_addr, addrs + segments - 1); | |
108 | ||
109 | addrs += segments - segments_left; | |
110 | memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs)); | |
111 | ||
112 | ipv6_addr_copy(addrs, &iph->daddr); | |
113 | ipv6_addr_copy(&iph->daddr, &final_addr); | |
114 | } | |
115 | ||
116 | static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len) | |
117 | { | |
118 | union { | |
119 | struct ipv6hdr *iph; | |
120 | struct ipv6_opt_hdr *opth; | |
121 | struct ipv6_rt_hdr *rth; | |
122 | char *raw; | |
123 | } exthdr = { .iph = iph }; | |
124 | char *end = exthdr.raw + len; | |
125 | int nexthdr = iph->nexthdr; | |
126 | ||
127 | exthdr.iph++; | |
128 | ||
129 | while (exthdr.raw < end) { | |
130 | switch (nexthdr) { | |
131 | case NEXTHDR_HOP: | |
132 | case NEXTHDR_DEST: | |
133 | if (!zero_out_mutable_opts(exthdr.opth)) { | |
64ce2073 | 134 | LIMIT_NETDEBUG( |
1da177e4 LT |
135 | KERN_WARNING "overrun %sopts\n", |
136 | nexthdr == NEXTHDR_HOP ? | |
64ce2073 | 137 | "hop" : "dest"); |
1da177e4 LT |
138 | return -EINVAL; |
139 | } | |
140 | break; | |
141 | ||
142 | case NEXTHDR_ROUTING: | |
143 | ipv6_rearrange_rthdr(iph, exthdr.rth); | |
144 | break; | |
145 | ||
146 | default : | |
147 | return 0; | |
148 | } | |
149 | ||
150 | nexthdr = exthdr.opth->nexthdr; | |
151 | exthdr.raw += ipv6_optlen(exthdr.opth); | |
152 | } | |
153 | ||
154 | return 0; | |
155 | } | |
156 | ||
157 | static int ah6_output(struct xfrm_state *x, struct sk_buff *skb) | |
158 | { | |
159 | int err; | |
160 | int extlen; | |
161 | struct ipv6hdr *top_iph; | |
162 | struct ip_auth_hdr *ah; | |
163 | struct ah_data *ahp; | |
164 | u8 nexthdr; | |
165 | char tmp_base[8]; | |
166 | struct { | |
167 | struct in6_addr daddr; | |
168 | char hdrs[0]; | |
169 | } *tmp_ext; | |
170 | ||
171 | top_iph = (struct ipv6hdr *)skb->data; | |
172 | top_iph->payload_len = htons(skb->len - sizeof(*top_iph)); | |
173 | ||
174 | nexthdr = *skb->nh.raw; | |
175 | *skb->nh.raw = IPPROTO_AH; | |
176 | ||
177 | /* When there are no extension headers, we only need to save the first | |
178 | * 8 bytes of the base IP header. | |
179 | */ | |
180 | memcpy(tmp_base, top_iph, sizeof(tmp_base)); | |
181 | ||
182 | tmp_ext = NULL; | |
183 | extlen = skb->h.raw - (unsigned char *)(top_iph + 1); | |
184 | if (extlen) { | |
185 | extlen += sizeof(*tmp_ext); | |
186 | tmp_ext = kmalloc(extlen, GFP_ATOMIC); | |
187 | if (!tmp_ext) { | |
188 | err = -ENOMEM; | |
189 | goto error; | |
190 | } | |
191 | memcpy(tmp_ext, &top_iph->daddr, extlen); | |
192 | err = ipv6_clear_mutable_options(top_iph, | |
193 | extlen - sizeof(*tmp_ext) + | |
194 | sizeof(*top_iph)); | |
195 | if (err) | |
196 | goto error_free_iph; | |
197 | } | |
198 | ||
199 | ah = (struct ip_auth_hdr *)skb->h.raw; | |
200 | ah->nexthdr = nexthdr; | |
201 | ||
202 | top_iph->priority = 0; | |
203 | top_iph->flow_lbl[0] = 0; | |
204 | top_iph->flow_lbl[1] = 0; | |
205 | top_iph->flow_lbl[2] = 0; | |
206 | top_iph->hop_limit = 0; | |
207 | ||
208 | ahp = x->data; | |
209 | ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + | |
210 | ahp->icv_trunc_len) >> 2) - 2; | |
211 | ||
212 | ah->reserved = 0; | |
213 | ah->spi = x->id.spi; | |
214 | ah->seq_no = htonl(++x->replay.oseq); | |
215 | ahp->icv(ahp, skb, ah->auth_data); | |
216 | ||
217 | err = 0; | |
218 | ||
219 | memcpy(top_iph, tmp_base, sizeof(tmp_base)); | |
220 | if (tmp_ext) { | |
221 | memcpy(&top_iph->daddr, tmp_ext, extlen); | |
222 | error_free_iph: | |
223 | kfree(tmp_ext); | |
224 | } | |
225 | ||
226 | error: | |
227 | return err; | |
228 | } | |
229 | ||
230 | static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) | |
231 | { | |
232 | /* | |
233 | * Before process AH | |
234 | * [IPv6][Ext1][Ext2][AH][Dest][Payload] | |
235 | * |<-------------->| hdr_len | |
236 | * | |
237 | * To erase AH: | |
238 | * Keeping copy of cleared headers. After AH processing, | |
239 | * Moving the pointer of skb->nh.raw by using skb_pull as long as AH | |
240 | * header length. Then copy back the copy as long as hdr_len | |
241 | * If destination header following AH exists, copy it into after [Ext2]. | |
242 | * | |
243 | * |<>|[IPv6][Ext1][Ext2][Dest][Payload] | |
244 | * There is offset of AH before IPv6 header after the process. | |
245 | */ | |
246 | ||
247 | struct ipv6_auth_hdr *ah; | |
248 | struct ah_data *ahp; | |
249 | unsigned char *tmp_hdr = NULL; | |
250 | u16 hdr_len; | |
251 | u16 ah_hlen; | |
252 | int nexthdr; | |
253 | ||
254 | if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) | |
255 | goto out; | |
256 | ||
257 | /* We are going to _remove_ AH header to keep sockets happy, | |
258 | * so... Later this can change. */ | |
259 | if (skb_cloned(skb) && | |
260 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
261 | goto out; | |
262 | ||
263 | hdr_len = skb->data - skb->nh.raw; | |
264 | ah = (struct ipv6_auth_hdr*)skb->data; | |
265 | ahp = x->data; | |
266 | nexthdr = ah->nexthdr; | |
267 | ah_hlen = (ah->hdrlen + 2) << 2; | |
268 | ||
269 | if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) && | |
270 | ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len)) | |
271 | goto out; | |
272 | ||
273 | if (!pskb_may_pull(skb, ah_hlen)) | |
274 | goto out; | |
275 | ||
276 | tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC); | |
277 | if (!tmp_hdr) | |
278 | goto out; | |
279 | memcpy(tmp_hdr, skb->nh.raw, hdr_len); | |
280 | if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len)) | |
281 | goto out; | |
282 | skb->nh.ipv6h->priority = 0; | |
283 | skb->nh.ipv6h->flow_lbl[0] = 0; | |
284 | skb->nh.ipv6h->flow_lbl[1] = 0; | |
285 | skb->nh.ipv6h->flow_lbl[2] = 0; | |
286 | skb->nh.ipv6h->hop_limit = 0; | |
287 | ||
288 | { | |
289 | u8 auth_data[MAX_AH_AUTH_LEN]; | |
290 | ||
291 | memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); | |
292 | memset(ah->auth_data, 0, ahp->icv_trunc_len); | |
293 | skb_push(skb, skb->data - skb->nh.raw); | |
294 | ahp->icv(ahp, skb, ah->auth_data); | |
295 | if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { | |
64ce2073 | 296 | LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n"); |
1da177e4 LT |
297 | x->stats.integrity_failed++; |
298 | goto free_out; | |
299 | } | |
300 | } | |
301 | ||
302 | skb->nh.raw = skb_pull(skb, ah_hlen); | |
303 | memcpy(skb->nh.raw, tmp_hdr, hdr_len); | |
304 | skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); | |
305 | skb_pull(skb, hdr_len); | |
306 | skb->h.raw = skb->data; | |
307 | ||
308 | ||
309 | kfree(tmp_hdr); | |
310 | ||
311 | return nexthdr; | |
312 | ||
313 | free_out: | |
314 | kfree(tmp_hdr); | |
315 | out: | |
316 | return -EINVAL; | |
317 | } | |
318 | ||
319 | static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, | |
320 | int type, int code, int offset, __u32 info) | |
321 | { | |
322 | struct ipv6hdr *iph = (struct ipv6hdr*)skb->data; | |
323 | struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset); | |
324 | struct xfrm_state *x; | |
325 | ||
326 | if (type != ICMPV6_DEST_UNREACH && | |
327 | type != ICMPV6_PKT_TOOBIG) | |
328 | return; | |
329 | ||
330 | x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6); | |
331 | if (!x) | |
332 | return; | |
333 | ||
64ce2073 PM |
334 | NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/" |
335 | "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n", | |
336 | ntohl(ah->spi), NIP6(iph->daddr)); | |
1da177e4 LT |
337 | |
338 | xfrm_state_put(x); | |
339 | } | |
340 | ||
72cb6962 | 341 | static int ah6_init_state(struct xfrm_state *x) |
1da177e4 LT |
342 | { |
343 | struct ah_data *ahp = NULL; | |
344 | struct xfrm_algo_desc *aalg_desc; | |
345 | ||
346 | if (!x->aalg) | |
347 | goto error; | |
348 | ||
349 | /* null auth can use a zero length key */ | |
350 | if (x->aalg->alg_key_len > 512) | |
351 | goto error; | |
352 | ||
353 | if (x->encap) | |
354 | goto error; | |
355 | ||
356 | ahp = kmalloc(sizeof(*ahp), GFP_KERNEL); | |
357 | if (ahp == NULL) | |
358 | return -ENOMEM; | |
359 | ||
360 | memset(ahp, 0, sizeof(*ahp)); | |
361 | ||
362 | ahp->key = x->aalg->alg_key; | |
363 | ahp->key_len = (x->aalg->alg_key_len+7)/8; | |
364 | ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); | |
365 | if (!ahp->tfm) | |
366 | goto error; | |
367 | ahp->icv = ah_hmac_digest; | |
368 | ||
369 | /* | |
370 | * Lookup the algorithm description maintained by xfrm_algo, | |
371 | * verify crypto transform properties, and store information | |
372 | * we need for AH processing. This lookup cannot fail here | |
373 | * after a successful crypto_alloc_tfm(). | |
374 | */ | |
375 | aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); | |
376 | BUG_ON(!aalg_desc); | |
377 | ||
378 | if (aalg_desc->uinfo.auth.icv_fullbits/8 != | |
379 | crypto_tfm_alg_digestsize(ahp->tfm)) { | |
380 | printk(KERN_INFO "AH: %s digestsize %u != %hu\n", | |
381 | x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm), | |
382 | aalg_desc->uinfo.auth.icv_fullbits/8); | |
383 | goto error; | |
384 | } | |
385 | ||
386 | ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; | |
387 | ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; | |
388 | ||
389 | BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); | |
390 | ||
391 | ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); | |
392 | if (!ahp->work_icv) | |
393 | goto error; | |
394 | ||
395 | x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len); | |
396 | if (x->props.mode) | |
397 | x->props.header_len += sizeof(struct ipv6hdr); | |
398 | x->data = ahp; | |
399 | ||
400 | return 0; | |
401 | ||
402 | error: | |
403 | if (ahp) { | |
573dbd95 JJ |
404 | kfree(ahp->work_icv); |
405 | crypto_free_tfm(ahp->tfm); | |
1da177e4 LT |
406 | kfree(ahp); |
407 | } | |
408 | return -EINVAL; | |
409 | } | |
410 | ||
411 | static void ah6_destroy(struct xfrm_state *x) | |
412 | { | |
413 | struct ah_data *ahp = x->data; | |
414 | ||
415 | if (!ahp) | |
416 | return; | |
417 | ||
573dbd95 JJ |
418 | kfree(ahp->work_icv); |
419 | ahp->work_icv = NULL; | |
420 | crypto_free_tfm(ahp->tfm); | |
421 | ahp->tfm = NULL; | |
1da177e4 LT |
422 | kfree(ahp); |
423 | } | |
424 | ||
425 | static struct xfrm_type ah6_type = | |
426 | { | |
427 | .description = "AH6", | |
428 | .owner = THIS_MODULE, | |
429 | .proto = IPPROTO_AH, | |
430 | .init_state = ah6_init_state, | |
431 | .destructor = ah6_destroy, | |
432 | .input = ah6_input, | |
433 | .output = ah6_output | |
434 | }; | |
435 | ||
436 | static struct inet6_protocol ah6_protocol = { | |
437 | .handler = xfrm6_rcv, | |
438 | .err_handler = ah6_err, | |
439 | .flags = INET6_PROTO_NOPOLICY, | |
440 | }; | |
441 | ||
442 | static int __init ah6_init(void) | |
443 | { | |
444 | if (xfrm_register_type(&ah6_type, AF_INET6) < 0) { | |
445 | printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n"); | |
446 | return -EAGAIN; | |
447 | } | |
448 | ||
449 | if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) { | |
450 | printk(KERN_INFO "ipv6 ah init: can't add protocol\n"); | |
451 | xfrm_unregister_type(&ah6_type, AF_INET6); | |
452 | return -EAGAIN; | |
453 | } | |
454 | ||
455 | return 0; | |
456 | } | |
457 | ||
458 | static void __exit ah6_fini(void) | |
459 | { | |
460 | if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0) | |
461 | printk(KERN_INFO "ipv6 ah close: can't remove protocol\n"); | |
462 | ||
463 | if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0) | |
464 | printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n"); | |
465 | ||
466 | } | |
467 | ||
468 | module_init(ah6_init); | |
469 | module_exit(ah6_fini); | |
470 | ||
471 | MODULE_LICENSE("GPL"); |