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Commit | Line | Data |
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07d4ee58 | 1 | #include <linux/err.h> |
1da177e4 LT |
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 | ||
d5a0a1e3 | 17 | static int ip_clear_mutable_options(struct iphdr *iph, __be32 *daddr) |
1da177e4 LT |
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. */ | |
11a03f78 | 38 | case IPOPT_CIPSO: |
1da177e4 LT |
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 | ||
eddc9ec5 | 68 | top_iph = ip_hdr(skb); |
1da177e4 LT |
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; | |
e905a9ed | 94 | ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + |
1da177e4 LT |
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); | |
9500e8a8 | 100 | xfrm_aevent_doreplay(x); |
07d4ee58 HX |
101 | err = ah_mac_digest(ahp, skb, ah->auth_data); |
102 | if (err) | |
103 | goto error; | |
104 | memcpy(ah->auth_data, ahp->work_icv, ahp->icv_trunc_len); | |
1da177e4 LT |
105 | |
106 | top_iph->tos = iph->tos; | |
107 | top_iph->ttl = iph->ttl; | |
108 | top_iph->frag_off = iph->frag_off; | |
109 | if (top_iph->ihl != 5) { | |
110 | top_iph->daddr = iph->daddr; | |
111 | memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); | |
112 | } | |
113 | ||
114 | ip_send_check(top_iph); | |
115 | ||
116 | err = 0; | |
117 | ||
118 | error: | |
119 | return err; | |
120 | } | |
121 | ||
e695633e | 122 | static int ah_input(struct xfrm_state *x, struct sk_buff *skb) |
1da177e4 LT |
123 | { |
124 | int ah_hlen; | |
31a4ab93 | 125 | int ihl; |
07d4ee58 | 126 | int err = -EINVAL; |
1da177e4 LT |
127 | struct iphdr *iph; |
128 | struct ip_auth_hdr *ah; | |
129 | struct ah_data *ahp; | |
130 | char work_buf[60]; | |
131 | ||
132 | if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) | |
133 | goto out; | |
134 | ||
135 | ah = (struct ip_auth_hdr*)skb->data; | |
136 | ahp = x->data; | |
137 | ah_hlen = (ah->hdrlen + 2) << 2; | |
e905a9ed | 138 | |
1da177e4 | 139 | if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) && |
e905a9ed | 140 | ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len)) |
1da177e4 LT |
141 | goto out; |
142 | ||
143 | if (!pskb_may_pull(skb, ah_hlen)) | |
144 | goto out; | |
145 | ||
146 | /* We are going to _remove_ AH header to keep sockets happy, | |
147 | * so... Later this can change. */ | |
148 | if (skb_cloned(skb) && | |
149 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
150 | goto out; | |
151 | ||
152 | skb->ip_summed = CHECKSUM_NONE; | |
153 | ||
154 | ah = (struct ip_auth_hdr*)skb->data; | |
eddc9ec5 | 155 | iph = ip_hdr(skb); |
1da177e4 | 156 | |
d56f90a7 | 157 | ihl = skb->data - skb_network_header(skb); |
31a4ab93 | 158 | memcpy(work_buf, iph, ihl); |
1da177e4 LT |
159 | |
160 | iph->ttl = 0; | |
161 | iph->tos = 0; | |
162 | iph->frag_off = 0; | |
163 | iph->check = 0; | |
31a4ab93 | 164 | if (ihl > sizeof(*iph)) { |
d5a0a1e3 | 165 | __be32 dummy; |
1da177e4 LT |
166 | if (ip_clear_mutable_options(iph, &dummy)) |
167 | goto out; | |
168 | } | |
e905a9ed | 169 | { |
1da177e4 | 170 | u8 auth_data[MAX_AH_AUTH_LEN]; |
e905a9ed | 171 | |
1da177e4 | 172 | memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); |
31a4ab93 | 173 | skb_push(skb, ihl); |
07d4ee58 HX |
174 | err = ah_mac_digest(ahp, skb, ah->auth_data); |
175 | if (err) | |
176 | goto out; | |
177 | err = -EINVAL; | |
178 | if (memcmp(ahp->work_icv, auth_data, ahp->icv_trunc_len)) { | |
1da177e4 LT |
179 | x->stats.integrity_failed++; |
180 | goto out; | |
181 | } | |
182 | } | |
183 | ((struct iphdr*)work_buf)->protocol = ah->nexthdr; | |
d56f90a7 | 184 | skb->nh.raw += ah_hlen; |
badff6d0 ACM |
185 | memcpy(skb_network_header(skb), work_buf, ihl); |
186 | skb->h.raw = skb->nh.raw; | |
31a4ab93 | 187 | __skb_pull(skb, ah_hlen + ihl); |
1da177e4 LT |
188 | |
189 | return 0; | |
190 | ||
191 | out: | |
07d4ee58 | 192 | return err; |
1da177e4 LT |
193 | } |
194 | ||
195 | static void ah4_err(struct sk_buff *skb, u32 info) | |
196 | { | |
197 | struct iphdr *iph = (struct iphdr*)skb->data; | |
198 | struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2)); | |
199 | struct xfrm_state *x; | |
200 | ||
88c7664f ACM |
201 | if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || |
202 | icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) | |
1da177e4 LT |
203 | return; |
204 | ||
205 | x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET); | |
206 | if (!x) | |
207 | return; | |
208 | printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", | |
209 | ntohl(ah->spi), ntohl(iph->daddr)); | |
210 | xfrm_state_put(x); | |
211 | } | |
212 | ||
72cb6962 | 213 | static int ah_init_state(struct xfrm_state *x) |
1da177e4 LT |
214 | { |
215 | struct ah_data *ahp = NULL; | |
216 | struct xfrm_algo_desc *aalg_desc; | |
07d4ee58 | 217 | struct crypto_hash *tfm; |
1da177e4 LT |
218 | |
219 | if (!x->aalg) | |
220 | goto error; | |
221 | ||
222 | /* null auth can use a zero length key */ | |
223 | if (x->aalg->alg_key_len > 512) | |
224 | goto error; | |
225 | ||
226 | if (x->encap) | |
227 | goto error; | |
228 | ||
0da974f4 | 229 | ahp = kzalloc(sizeof(*ahp), GFP_KERNEL); |
1da177e4 LT |
230 | if (ahp == NULL) |
231 | return -ENOMEM; | |
232 | ||
1da177e4 LT |
233 | ahp->key = x->aalg->alg_key; |
234 | ahp->key_len = (x->aalg->alg_key_len+7)/8; | |
07d4ee58 HX |
235 | tfm = crypto_alloc_hash(x->aalg->alg_name, 0, CRYPTO_ALG_ASYNC); |
236 | if (IS_ERR(tfm)) | |
237 | goto error; | |
238 | ||
239 | ahp->tfm = tfm; | |
240 | if (crypto_hash_setkey(tfm, ahp->key, ahp->key_len)) | |
1da177e4 | 241 | goto error; |
e905a9ed | 242 | |
1da177e4 LT |
243 | /* |
244 | * Lookup the algorithm description maintained by xfrm_algo, | |
245 | * verify crypto transform properties, and store information | |
246 | * we need for AH processing. This lookup cannot fail here | |
07d4ee58 | 247 | * after a successful crypto_alloc_hash(). |
1da177e4 LT |
248 | */ |
249 | aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); | |
250 | BUG_ON(!aalg_desc); | |
251 | ||
252 | if (aalg_desc->uinfo.auth.icv_fullbits/8 != | |
07d4ee58 | 253 | crypto_hash_digestsize(tfm)) { |
1da177e4 | 254 | printk(KERN_INFO "AH: %s digestsize %u != %hu\n", |
07d4ee58 | 255 | x->aalg->alg_name, crypto_hash_digestsize(tfm), |
1da177e4 LT |
256 | aalg_desc->uinfo.auth.icv_fullbits/8); |
257 | goto error; | |
258 | } | |
e905a9ed | 259 | |
1da177e4 LT |
260 | ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; |
261 | ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; | |
e905a9ed | 262 | |
1da177e4 | 263 | BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); |
e905a9ed | 264 | |
1da177e4 LT |
265 | ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); |
266 | if (!ahp->work_icv) | |
267 | goto error; | |
e905a9ed | 268 | |
1da177e4 | 269 | x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len); |
7e49e6de | 270 | if (x->props.mode == XFRM_MODE_TUNNEL) |
1da177e4 LT |
271 | x->props.header_len += sizeof(struct iphdr); |
272 | x->data = ahp; | |
273 | ||
274 | return 0; | |
275 | ||
276 | error: | |
277 | if (ahp) { | |
573dbd95 | 278 | kfree(ahp->work_icv); |
07d4ee58 | 279 | crypto_free_hash(ahp->tfm); |
1da177e4 LT |
280 | kfree(ahp); |
281 | } | |
282 | return -EINVAL; | |
283 | } | |
284 | ||
285 | static void ah_destroy(struct xfrm_state *x) | |
286 | { | |
287 | struct ah_data *ahp = x->data; | |
288 | ||
289 | if (!ahp) | |
290 | return; | |
291 | ||
573dbd95 JJ |
292 | kfree(ahp->work_icv); |
293 | ahp->work_icv = NULL; | |
07d4ee58 | 294 | crypto_free_hash(ahp->tfm); |
573dbd95 | 295 | ahp->tfm = NULL; |
1da177e4 LT |
296 | kfree(ahp); |
297 | } | |
298 | ||
299 | ||
300 | static struct xfrm_type ah_type = | |
301 | { | |
302 | .description = "AH4", | |
303 | .owner = THIS_MODULE, | |
304 | .proto = IPPROTO_AH, | |
305 | .init_state = ah_init_state, | |
306 | .destructor = ah_destroy, | |
307 | .input = ah_input, | |
308 | .output = ah_output | |
309 | }; | |
310 | ||
311 | static struct net_protocol ah4_protocol = { | |
312 | .handler = xfrm4_rcv, | |
313 | .err_handler = ah4_err, | |
314 | .no_policy = 1, | |
315 | }; | |
316 | ||
317 | static int __init ah4_init(void) | |
318 | { | |
319 | if (xfrm_register_type(&ah_type, AF_INET) < 0) { | |
320 | printk(KERN_INFO "ip ah init: can't add xfrm type\n"); | |
321 | return -EAGAIN; | |
322 | } | |
323 | if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { | |
324 | printk(KERN_INFO "ip ah init: can't add protocol\n"); | |
325 | xfrm_unregister_type(&ah_type, AF_INET); | |
326 | return -EAGAIN; | |
327 | } | |
328 | return 0; | |
329 | } | |
330 | ||
331 | static void __exit ah4_fini(void) | |
332 | { | |
333 | if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) | |
334 | printk(KERN_INFO "ip ah close: can't remove protocol\n"); | |
335 | if (xfrm_unregister_type(&ah_type, AF_INET) < 0) | |
336 | printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); | |
337 | } | |
338 | ||
339 | module_init(ah4_init); | |
340 | module_exit(ah4_fini); | |
341 | MODULE_LICENSE("GPL"); |