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> 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); 99 ahp->icv(ahp, skb, ah->auth_data); 100 101 top_iph->tos = iph->tos; 102 top_iph->ttl = iph->ttl; 103 top_iph->frag_off = iph->frag_off; 104 if (top_iph->ihl != 5) { 105 top_iph->daddr = iph->daddr; 106 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 107 } 108 109 ip_send_check(top_iph); 110 111 err = 0; 112 113 error: 114 return err; 115 } 116 117 static int ah_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 118 { 119 int ah_hlen; 120 struct iphdr *iph; 121 struct ip_auth_hdr *ah; 122 struct ah_data *ahp; 123 char work_buf[60]; 124 125 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) 126 goto out; 127 128 ah = (struct ip_auth_hdr*)skb->data; 129 ahp = x->data; 130 ah_hlen = (ah->hdrlen + 2) << 2; 131 132 if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) && 133 ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len)) 134 goto out; 135 136 if (!pskb_may_pull(skb, ah_hlen)) 137 goto out; 138 139 /* We are going to _remove_ AH header to keep sockets happy, 140 * so... Later this can change. */ 141 if (skb_cloned(skb) && 142 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 143 goto out; 144 145 skb->ip_summed = CHECKSUM_NONE; 146 147 ah = (struct ip_auth_hdr*)skb->data; 148 iph = skb->nh.iph; 149 150 memcpy(work_buf, iph, iph->ihl*4); 151 152 iph->ttl = 0; 153 iph->tos = 0; 154 iph->frag_off = 0; 155 iph->check = 0; 156 if (iph->ihl != 5) { 157 u32 dummy; 158 if (ip_clear_mutable_options(iph, &dummy)) 159 goto out; 160 } 161 { 162 u8 auth_data[MAX_AH_AUTH_LEN]; 163 164 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 165 skb_push(skb, skb->data - skb->nh.raw); 166 ahp->icv(ahp, skb, ah->auth_data); 167 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { 168 x->stats.integrity_failed++; 169 goto out; 170 } 171 } 172 ((struct iphdr*)work_buf)->protocol = ah->nexthdr; 173 skb->nh.raw = skb_pull(skb, ah_hlen); 174 memcpy(skb->nh.raw, work_buf, iph->ihl*4); 175 skb->nh.iph->tot_len = htons(skb->len); 176 skb_pull(skb, skb->nh.iph->ihl*4); 177 skb->h.raw = skb->data; 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 } 202 203 static int ah_init_state(struct xfrm_state *x) 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; 217 218 ahp = kmalloc(sizeof(*ahp), GFP_KERNEL); 219 if (ahp == NULL) 220 return -ENOMEM; 221 222 memset(ahp, 0, sizeof(*ahp)); 223 224 ahp->key = x->aalg->alg_key; 225 ahp->key_len = (x->aalg->alg_key_len+7)/8; 226 ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 227 if (!ahp->tfm) 228 goto error; 229 ahp->icv = ah_hmac_digest; 230 231 /* 232 * Lookup the algorithm description maintained by xfrm_algo, 233 * verify crypto transform properties, and store information 234 * we need for AH processing. This lookup cannot fail here 235 * after a successful crypto_alloc_tfm(). 236 */ 237 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 238 BUG_ON(!aalg_desc); 239 240 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 241 crypto_tfm_alg_digestsize(ahp->tfm)) { 242 printk(KERN_INFO "AH: %s digestsize %u != %hu\n", 243 x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm), 244 aalg_desc->uinfo.auth.icv_fullbits/8); 245 goto error; 246 } 247 248 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 249 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 250 251 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); 252 253 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); 254 if (!ahp->work_icv) 255 goto error; 256 257 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len); 258 if (x->props.mode) 259 x->props.header_len += sizeof(struct iphdr); 260 x->data = ahp; 261 262 return 0; 263 264 error: 265 if (ahp) { 266 kfree(ahp->work_icv); 267 crypto_free_tfm(ahp->tfm); 268 kfree(ahp); 269 } 270 return -EINVAL; 271 } 272 273 static void ah_destroy(struct xfrm_state *x) 274 { 275 struct ah_data *ahp = x->data; 276 277 if (!ahp) 278 return; 279 280 kfree(ahp->work_icv); 281 ahp->work_icv = NULL; 282 crypto_free_tfm(ahp->tfm); 283 ahp->tfm = NULL; 284 kfree(ahp); 285 } 286 287 288 static struct xfrm_type ah_type = 289 { 290 .description = "AH4", 291 .owner = THIS_MODULE, 292 .proto = IPPROTO_AH, 293 .init_state = ah_init_state, 294 .destructor = ah_destroy, 295 .input = ah_input, 296 .output = ah_output 297 }; 298 299 static struct net_protocol ah4_protocol = { 300 .handler = xfrm4_rcv, 301 .err_handler = ah4_err, 302 .no_policy = 1, 303 }; 304 305 static int __init ah4_init(void) 306 { 307 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 308 printk(KERN_INFO "ip ah init: can't add xfrm type\n"); 309 return -EAGAIN; 310 } 311 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { 312 printk(KERN_INFO "ip ah init: can't add protocol\n"); 313 xfrm_unregister_type(&ah_type, AF_INET); 314 return -EAGAIN; 315 } 316 return 0; 317 } 318 319 static void __exit ah4_fini(void) 320 { 321 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) 322 printk(KERN_INFO "ip ah close: can't remove protocol\n"); 323 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 324 printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); 325 } 326 327 module_init(ah4_init); 328 module_exit(ah4_fini); 329 MODULE_LICENSE("GPL"); 330