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Commit | Line | Data |
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1da177e4 LT |
1 | #include <linux/module.h> |
2 | #include <net/ip.h> | |
3 | #include <net/xfrm.h> | |
4 | #include <net/ah.h> | |
5 | #include <linux/crypto.h> | |
6 | #include <linux/pfkeyv2.h> | |
7 | #include <net/icmp.h> | |
14c85021 | 8 | #include <net/protocol.h> |
1da177e4 LT |
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); | |
9500e8a8 | 99 | xfrm_aevent_doreplay(x); |
1da177e4 LT |
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 | ||
e695633e | 118 | static int ah_input(struct xfrm_state *x, struct sk_buff *skb) |
1da177e4 LT |
119 | { |
120 | int ah_hlen; | |
31a4ab93 | 121 | int ihl; |
1da177e4 LT |
122 | struct iphdr *iph; |
123 | struct ip_auth_hdr *ah; | |
124 | struct ah_data *ahp; | |
125 | char work_buf[60]; | |
126 | ||
127 | if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) | |
128 | goto out; | |
129 | ||
130 | ah = (struct ip_auth_hdr*)skb->data; | |
131 | ahp = x->data; | |
132 | ah_hlen = (ah->hdrlen + 2) << 2; | |
133 | ||
134 | if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) && | |
135 | ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len)) | |
136 | goto out; | |
137 | ||
138 | if (!pskb_may_pull(skb, ah_hlen)) | |
139 | goto out; | |
140 | ||
141 | /* We are going to _remove_ AH header to keep sockets happy, | |
142 | * so... Later this can change. */ | |
143 | if (skb_cloned(skb) && | |
144 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
145 | goto out; | |
146 | ||
147 | skb->ip_summed = CHECKSUM_NONE; | |
148 | ||
149 | ah = (struct ip_auth_hdr*)skb->data; | |
150 | iph = skb->nh.iph; | |
151 | ||
31a4ab93 HX |
152 | ihl = skb->data - skb->nh.raw; |
153 | memcpy(work_buf, iph, ihl); | |
1da177e4 LT |
154 | |
155 | iph->ttl = 0; | |
156 | iph->tos = 0; | |
157 | iph->frag_off = 0; | |
158 | iph->check = 0; | |
31a4ab93 | 159 | if (ihl > sizeof(*iph)) { |
1da177e4 LT |
160 | u32 dummy; |
161 | if (ip_clear_mutable_options(iph, &dummy)) | |
162 | goto out; | |
163 | } | |
164 | { | |
165 | u8 auth_data[MAX_AH_AUTH_LEN]; | |
166 | ||
167 | memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); | |
31a4ab93 | 168 | skb_push(skb, ihl); |
1da177e4 LT |
169 | ahp->icv(ahp, skb, ah->auth_data); |
170 | if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { | |
171 | x->stats.integrity_failed++; | |
172 | goto out; | |
173 | } | |
174 | } | |
175 | ((struct iphdr*)work_buf)->protocol = ah->nexthdr; | |
31a4ab93 HX |
176 | skb->h.raw = memcpy(skb->nh.raw += ah_hlen, work_buf, ihl); |
177 | __skb_pull(skb, ah_hlen + ihl); | |
1da177e4 LT |
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 | ||
0da974f4 | 218 | ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); |
1da177e4 LT |
219 | if (ahp == NULL) |
220 | return -ENOMEM; | |
221 | ||
1da177e4 LT |
222 | ahp->key = x->aalg->alg_key; |
223 | ahp->key_len = (x->aalg->alg_key_len+7)/8; | |
224 | ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); | |
225 | if (!ahp->tfm) | |
226 | goto error; | |
227 | ahp->icv = ah_hmac_digest; | |
228 | ||
229 | /* | |
230 | * Lookup the algorithm description maintained by xfrm_algo, | |
231 | * verify crypto transform properties, and store information | |
232 | * we need for AH processing. This lookup cannot fail here | |
233 | * after a successful crypto_alloc_tfm(). | |
234 | */ | |
235 | aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); | |
236 | BUG_ON(!aalg_desc); | |
237 | ||
238 | if (aalg_desc->uinfo.auth.icv_fullbits/8 != | |
239 | crypto_tfm_alg_digestsize(ahp->tfm)) { | |
240 | printk(KERN_INFO "AH: %s digestsize %u != %hu\n", | |
241 | x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm), | |
242 | aalg_desc->uinfo.auth.icv_fullbits/8); | |
243 | goto error; | |
244 | } | |
245 | ||
246 | ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; | |
247 | ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; | |
248 | ||
249 | BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); | |
250 | ||
251 | ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); | |
252 | if (!ahp->work_icv) | |
253 | goto error; | |
254 | ||
255 | x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len); | |
256 | if (x->props.mode) | |
257 | x->props.header_len += sizeof(struct iphdr); | |
258 | x->data = ahp; | |
259 | ||
260 | return 0; | |
261 | ||
262 | error: | |
263 | if (ahp) { | |
573dbd95 JJ |
264 | kfree(ahp->work_icv); |
265 | crypto_free_tfm(ahp->tfm); | |
1da177e4 LT |
266 | kfree(ahp); |
267 | } | |
268 | return -EINVAL; | |
269 | } | |
270 | ||
271 | static void ah_destroy(struct xfrm_state *x) | |
272 | { | |
273 | struct ah_data *ahp = x->data; | |
274 | ||
275 | if (!ahp) | |
276 | return; | |
277 | ||
573dbd95 JJ |
278 | kfree(ahp->work_icv); |
279 | ahp->work_icv = NULL; | |
280 | crypto_free_tfm(ahp->tfm); | |
281 | ahp->tfm = NULL; | |
1da177e4 LT |
282 | kfree(ahp); |
283 | } | |
284 | ||
285 | ||
286 | static struct xfrm_type ah_type = | |
287 | { | |
288 | .description = "AH4", | |
289 | .owner = THIS_MODULE, | |
290 | .proto = IPPROTO_AH, | |
291 | .init_state = ah_init_state, | |
292 | .destructor = ah_destroy, | |
293 | .input = ah_input, | |
294 | .output = ah_output | |
295 | }; | |
296 | ||
297 | static struct net_protocol ah4_protocol = { | |
298 | .handler = xfrm4_rcv, | |
299 | .err_handler = ah4_err, | |
300 | .no_policy = 1, | |
301 | }; | |
302 | ||
303 | static int __init ah4_init(void) | |
304 | { | |
305 | if (xfrm_register_type(&ah_type, AF_INET) < 0) { | |
306 | printk(KERN_INFO "ip ah init: can't add xfrm type\n"); | |
307 | return -EAGAIN; | |
308 | } | |
309 | if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { | |
310 | printk(KERN_INFO "ip ah init: can't add protocol\n"); | |
311 | xfrm_unregister_type(&ah_type, AF_INET); | |
312 | return -EAGAIN; | |
313 | } | |
314 | return 0; | |
315 | } | |
316 | ||
317 | static void __exit ah4_fini(void) | |
318 | { | |
319 | if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) | |
320 | printk(KERN_INFO "ip ah close: can't remove protocol\n"); | |
321 | if (xfrm_unregister_type(&ah_type, AF_INET) < 0) | |
322 | printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); | |
323 | } | |
324 | ||
325 | module_init(ah4_init); | |
326 | module_exit(ah4_fini); | |
327 | MODULE_LICENSE("GPL"); |