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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> | |
14c85021 | 9 | #include <net/protocol.h> |
1da177e4 LT |
10 | #include <asm/scatterlist.h> |
11 | ||
12 | ||
13 | /* Clear mutable options and find final destination to substitute | |
14 | * into IP header for icv calculation. Options are already checked | |
15 | * for validity, so paranoia is not required. */ | |
16 | ||
17 | static int ip_clear_mutable_options(struct iphdr *iph, u32 *daddr) | |
18 | { | |
19 | unsigned char * optptr = (unsigned char*)(iph+1); | |
20 | int l = iph->ihl*4 - sizeof(struct iphdr); | |
21 | int optlen; | |
22 | ||
23 | while (l > 0) { | |
24 | switch (*optptr) { | |
25 | case IPOPT_END: | |
26 | return 0; | |
27 | case IPOPT_NOOP: | |
28 | l--; | |
29 | optptr++; | |
30 | continue; | |
31 | } | |
32 | optlen = optptr[1]; | |
33 | if (optlen<2 || optlen>l) | |
34 | return -EINVAL; | |
35 | switch (*optptr) { | |
36 | case IPOPT_SEC: | |
37 | case 0x85: /* Some "Extended Security" crap. */ | |
38 | case 0x86: /* Another "Commercial Security" crap. */ | |
39 | case IPOPT_RA: | |
40 | case 0x80|21: /* RFC1770 */ | |
41 | break; | |
42 | case IPOPT_LSRR: | |
43 | case IPOPT_SSRR: | |
44 | if (optlen < 6) | |
45 | return -EINVAL; | |
46 | memcpy(daddr, optptr+optlen-4, 4); | |
47 | /* Fall through */ | |
48 | default: | |
49 | memset(optptr+2, 0, optlen-2); | |
50 | } | |
51 | l -= optlen; | |
52 | optptr += optlen; | |
53 | } | |
54 | return 0; | |
55 | } | |
56 | ||
57 | static int ah_output(struct xfrm_state *x, struct sk_buff *skb) | |
58 | { | |
59 | int err; | |
60 | struct iphdr *iph, *top_iph; | |
61 | struct ip_auth_hdr *ah; | |
62 | struct ah_data *ahp; | |
63 | union { | |
64 | struct iphdr iph; | |
65 | char buf[60]; | |
66 | } tmp_iph; | |
67 | ||
68 | top_iph = skb->nh.iph; | |
69 | iph = &tmp_iph.iph; | |
70 | ||
71 | iph->tos = top_iph->tos; | |
72 | iph->ttl = top_iph->ttl; | |
73 | iph->frag_off = top_iph->frag_off; | |
74 | ||
75 | if (top_iph->ihl != 5) { | |
76 | iph->daddr = top_iph->daddr; | |
77 | memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); | |
78 | err = ip_clear_mutable_options(top_iph, &top_iph->daddr); | |
79 | if (err) | |
80 | goto error; | |
81 | } | |
82 | ||
83 | ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4); | |
84 | ah->nexthdr = top_iph->protocol; | |
85 | ||
86 | top_iph->tos = 0; | |
87 | top_iph->tot_len = htons(skb->len); | |
88 | top_iph->frag_off = 0; | |
89 | top_iph->ttl = 0; | |
90 | top_iph->protocol = IPPROTO_AH; | |
91 | top_iph->check = 0; | |
92 | ||
93 | ahp = x->data; | |
94 | ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + | |
95 | ahp->icv_trunc_len) >> 2) - 2; | |
96 | ||
97 | ah->reserved = 0; | |
98 | ah->spi = x->id.spi; | |
99 | ah->seq_no = htonl(++x->replay.oseq); | |
100 | ahp->icv(ahp, skb, ah->auth_data); | |
101 | ||
102 | top_iph->tos = iph->tos; | |
103 | top_iph->ttl = iph->ttl; | |
104 | top_iph->frag_off = iph->frag_off; | |
105 | if (top_iph->ihl != 5) { | |
106 | top_iph->daddr = iph->daddr; | |
107 | memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); | |
108 | } | |
109 | ||
110 | ip_send_check(top_iph); | |
111 | ||
112 | err = 0; | |
113 | ||
114 | error: | |
115 | return err; | |
116 | } | |
117 | ||
118 | static int ah_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) | |
119 | { | |
120 | int ah_hlen; | |
121 | struct iphdr *iph; | |
122 | struct ip_auth_hdr *ah; | |
123 | struct ah_data *ahp; | |
124 | char work_buf[60]; | |
125 | ||
126 | if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) | |
127 | goto out; | |
128 | ||
129 | ah = (struct ip_auth_hdr*)skb->data; | |
130 | ahp = x->data; | |
131 | ah_hlen = (ah->hdrlen + 2) << 2; | |
132 | ||
133 | if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) && | |
134 | ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len)) | |
135 | goto out; | |
136 | ||
137 | if (!pskb_may_pull(skb, ah_hlen)) | |
138 | goto out; | |
139 | ||
140 | /* We are going to _remove_ AH header to keep sockets happy, | |
141 | * so... Later this can change. */ | |
142 | if (skb_cloned(skb) && | |
143 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
144 | goto out; | |
145 | ||
146 | skb->ip_summed = CHECKSUM_NONE; | |
147 | ||
148 | ah = (struct ip_auth_hdr*)skb->data; | |
149 | iph = skb->nh.iph; | |
150 | ||
151 | memcpy(work_buf, iph, iph->ihl*4); | |
152 | ||
153 | iph->ttl = 0; | |
154 | iph->tos = 0; | |
155 | iph->frag_off = 0; | |
156 | iph->check = 0; | |
157 | if (iph->ihl != 5) { | |
158 | u32 dummy; | |
159 | if (ip_clear_mutable_options(iph, &dummy)) | |
160 | goto out; | |
161 | } | |
162 | { | |
163 | u8 auth_data[MAX_AH_AUTH_LEN]; | |
164 | ||
165 | memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); | |
166 | skb_push(skb, skb->data - skb->nh.raw); | |
167 | ahp->icv(ahp, skb, ah->auth_data); | |
168 | if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { | |
169 | x->stats.integrity_failed++; | |
170 | goto out; | |
171 | } | |
172 | } | |
173 | ((struct iphdr*)work_buf)->protocol = ah->nexthdr; | |
174 | skb->nh.raw = skb_pull(skb, ah_hlen); | |
175 | memcpy(skb->nh.raw, work_buf, iph->ihl*4); | |
176 | skb->nh.iph->tot_len = htons(skb->len); | |
177 | skb_pull(skb, skb->nh.iph->ihl*4); | |
178 | skb->h.raw = skb->data; | |
179 | ||
180 | return 0; | |
181 | ||
182 | out: | |
183 | return -EINVAL; | |
184 | } | |
185 | ||
186 | static void ah4_err(struct sk_buff *skb, u32 info) | |
187 | { | |
188 | struct iphdr *iph = (struct iphdr*)skb->data; | |
189 | struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2)); | |
190 | struct xfrm_state *x; | |
191 | ||
192 | if (skb->h.icmph->type != ICMP_DEST_UNREACH || | |
193 | skb->h.icmph->code != ICMP_FRAG_NEEDED) | |
194 | return; | |
195 | ||
196 | x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET); | |
197 | if (!x) | |
198 | return; | |
199 | printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", | |
200 | ntohl(ah->spi), ntohl(iph->daddr)); | |
201 | xfrm_state_put(x); | |
202 | } | |
203 | ||
72cb6962 | 204 | static int ah_init_state(struct xfrm_state *x) |
1da177e4 LT |
205 | { |
206 | struct ah_data *ahp = NULL; | |
207 | struct xfrm_algo_desc *aalg_desc; | |
208 | ||
209 | if (!x->aalg) | |
210 | goto error; | |
211 | ||
212 | /* null auth can use a zero length key */ | |
213 | if (x->aalg->alg_key_len > 512) | |
214 | goto error; | |
215 | ||
216 | if (x->encap) | |
217 | goto error; | |
218 | ||
219 | ahp = kmalloc(sizeof(*ahp), GFP_KERNEL); | |
220 | if (ahp == NULL) | |
221 | return -ENOMEM; | |
222 | ||
223 | memset(ahp, 0, sizeof(*ahp)); | |
224 | ||
225 | ahp->key = x->aalg->alg_key; | |
226 | ahp->key_len = (x->aalg->alg_key_len+7)/8; | |
227 | ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); | |
228 | if (!ahp->tfm) | |
229 | goto error; | |
230 | ahp->icv = ah_hmac_digest; | |
231 | ||
232 | /* | |
233 | * Lookup the algorithm description maintained by xfrm_algo, | |
234 | * verify crypto transform properties, and store information | |
235 | * we need for AH processing. This lookup cannot fail here | |
236 | * after a successful crypto_alloc_tfm(). | |
237 | */ | |
238 | aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); | |
239 | BUG_ON(!aalg_desc); | |
240 | ||
241 | if (aalg_desc->uinfo.auth.icv_fullbits/8 != | |
242 | crypto_tfm_alg_digestsize(ahp->tfm)) { | |
243 | printk(KERN_INFO "AH: %s digestsize %u != %hu\n", | |
244 | x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm), | |
245 | aalg_desc->uinfo.auth.icv_fullbits/8); | |
246 | goto error; | |
247 | } | |
248 | ||
249 | ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; | |
250 | ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; | |
251 | ||
252 | BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); | |
253 | ||
254 | ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); | |
255 | if (!ahp->work_icv) | |
256 | goto error; | |
257 | ||
258 | x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len); | |
259 | if (x->props.mode) | |
260 | x->props.header_len += sizeof(struct iphdr); | |
261 | x->data = ahp; | |
262 | ||
263 | return 0; | |
264 | ||
265 | error: | |
266 | if (ahp) { | |
573dbd95 JJ |
267 | kfree(ahp->work_icv); |
268 | crypto_free_tfm(ahp->tfm); | |
1da177e4 LT |
269 | kfree(ahp); |
270 | } | |
271 | return -EINVAL; | |
272 | } | |
273 | ||
274 | static void ah_destroy(struct xfrm_state *x) | |
275 | { | |
276 | struct ah_data *ahp = x->data; | |
277 | ||
278 | if (!ahp) | |
279 | return; | |
280 | ||
573dbd95 JJ |
281 | kfree(ahp->work_icv); |
282 | ahp->work_icv = NULL; | |
283 | crypto_free_tfm(ahp->tfm); | |
284 | ahp->tfm = NULL; | |
1da177e4 LT |
285 | kfree(ahp); |
286 | } | |
287 | ||
288 | ||
289 | static struct xfrm_type ah_type = | |
290 | { | |
291 | .description = "AH4", | |
292 | .owner = THIS_MODULE, | |
293 | .proto = IPPROTO_AH, | |
294 | .init_state = ah_init_state, | |
295 | .destructor = ah_destroy, | |
296 | .input = ah_input, | |
297 | .output = ah_output | |
298 | }; | |
299 | ||
300 | static struct net_protocol ah4_protocol = { | |
301 | .handler = xfrm4_rcv, | |
302 | .err_handler = ah4_err, | |
303 | .no_policy = 1, | |
304 | }; | |
305 | ||
306 | static int __init ah4_init(void) | |
307 | { | |
308 | if (xfrm_register_type(&ah_type, AF_INET) < 0) { | |
309 | printk(KERN_INFO "ip ah init: can't add xfrm type\n"); | |
310 | return -EAGAIN; | |
311 | } | |
312 | if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { | |
313 | printk(KERN_INFO "ip ah init: can't add protocol\n"); | |
314 | xfrm_unregister_type(&ah_type, AF_INET); | |
315 | return -EAGAIN; | |
316 | } | |
317 | return 0; | |
318 | } | |
319 | ||
320 | static void __exit ah4_fini(void) | |
321 | { | |
322 | if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) | |
323 | printk(KERN_INFO "ip ah close: can't remove protocol\n"); | |
324 | if (xfrm_unregister_type(&ah_type, AF_INET) < 0) | |
325 | printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); | |
326 | } | |
327 | ||
328 | module_init(ah4_init); | |
329 | module_exit(ah4_fini); | |
330 | MODULE_LICENSE("GPL"); |