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 <net/protocol.h> 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 xfrm_aevent_doreplay(x); 101 ahp->icv(ahp, skb, ah->auth_data); 102 103 top_iph->tos = iph->tos; 104 top_iph->ttl = iph->ttl; 105 top_iph->frag_off = iph->frag_off; 106 if (top_iph->ihl != 5) { 107 top_iph->daddr = iph->daddr; 108 memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr)); 109 } 110 111 ip_send_check(top_iph); 112 113 err = 0; 114 115 error: 116 return err; 117 } 118 119 static int ah_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb) 120 { 121 int ah_hlen; 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; 151 152 memcpy(work_buf, iph, iph->ihl*4); 153 154 iph->ttl = 0; 155 iph->tos = 0; 156 iph->frag_off = 0; 157 iph->check = 0; 158 if (iph->ihl != 5) { 159 u32 dummy; 160 if (ip_clear_mutable_options(iph, &dummy)) 161 goto out; 162 } 163 { 164 u8 auth_data[MAX_AH_AUTH_LEN]; 165 166 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 167 skb_push(skb, skb->data - skb->nh.raw); 168 ahp->icv(ahp, skb, ah->auth_data); 169 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { 170 x->stats.integrity_failed++; 171 goto out; 172 } 173 } 174 ((struct iphdr*)work_buf)->protocol = ah->nexthdr; 175 skb->nh.raw = skb_pull(skb, ah_hlen); 176 memcpy(skb->nh.raw, work_buf, iph->ihl*4); 177 skb->nh.iph->tot_len = htons(skb->len); 178 skb_pull(skb, skb->nh.iph->ihl*4); 179 skb->h.raw = skb->data; 180 181 return 0; 182 183 out: 184 return -EINVAL; 185 } 186 187 static void ah4_err(struct sk_buff *skb, u32 info) 188 { 189 struct iphdr *iph = (struct iphdr*)skb->data; 190 struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+(iph->ihl<<2)); 191 struct xfrm_state *x; 192 193 if (skb->h.icmph->type != ICMP_DEST_UNREACH || 194 skb->h.icmph->code != ICMP_FRAG_NEEDED) 195 return; 196 197 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET); 198 if (!x) 199 return; 200 printk(KERN_DEBUG "pmtu discovery on SA AH/%08x/%08x\n", 201 ntohl(ah->spi), ntohl(iph->daddr)); 202 xfrm_state_put(x); 203 } 204 205 static int ah_init_state(struct xfrm_state *x) 206 { 207 struct ah_data *ahp = NULL; 208 struct xfrm_algo_desc *aalg_desc; 209 210 if (!x->aalg) 211 goto error; 212 213 /* null auth can use a zero length key */ 214 if (x->aalg->alg_key_len > 512) 215 goto error; 216 217 if (x->encap) 218 goto error; 219 220 ahp = kmalloc(sizeof(*ahp), GFP_KERNEL); 221 if (ahp == NULL) 222 return -ENOMEM; 223 224 memset(ahp, 0, sizeof(*ahp)); 225 226 ahp->key = x->aalg->alg_key; 227 ahp->key_len = (x->aalg->alg_key_len+7)/8; 228 ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0); 229 if (!ahp->tfm) 230 goto error; 231 ahp->icv = ah_hmac_digest; 232 233 /* 234 * Lookup the algorithm description maintained by xfrm_algo, 235 * verify crypto transform properties, and store information 236 * we need for AH processing. This lookup cannot fail here 237 * after a successful crypto_alloc_tfm(). 238 */ 239 aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0); 240 BUG_ON(!aalg_desc); 241 242 if (aalg_desc->uinfo.auth.icv_fullbits/8 != 243 crypto_tfm_alg_digestsize(ahp->tfm)) { 244 printk(KERN_INFO "AH: %s digestsize %u != %hu\n", 245 x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->tfm), 246 aalg_desc->uinfo.auth.icv_fullbits/8); 247 goto error; 248 } 249 250 ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8; 251 ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8; 252 253 BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN); 254 255 ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL); 256 if (!ahp->work_icv) 257 goto error; 258 259 x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len); 260 if (x->props.mode) 261 x->props.header_len += sizeof(struct iphdr); 262 x->data = ahp; 263 264 return 0; 265 266 error: 267 if (ahp) { 268 kfree(ahp->work_icv); 269 crypto_free_tfm(ahp->tfm); 270 kfree(ahp); 271 } 272 return -EINVAL; 273 } 274 275 static void ah_destroy(struct xfrm_state *x) 276 { 277 struct ah_data *ahp = x->data; 278 279 if (!ahp) 280 return; 281 282 kfree(ahp->work_icv); 283 ahp->work_icv = NULL; 284 crypto_free_tfm(ahp->tfm); 285 ahp->tfm = NULL; 286 kfree(ahp); 287 } 288 289 290 static struct xfrm_type ah_type = 291 { 292 .description = "AH4", 293 .owner = THIS_MODULE, 294 .proto = IPPROTO_AH, 295 .init_state = ah_init_state, 296 .destructor = ah_destroy, 297 .input = ah_input, 298 .output = ah_output 299 }; 300 301 static struct net_protocol ah4_protocol = { 302 .handler = xfrm4_rcv, 303 .err_handler = ah4_err, 304 .no_policy = 1, 305 }; 306 307 static int __init ah4_init(void) 308 { 309 if (xfrm_register_type(&ah_type, AF_INET) < 0) { 310 printk(KERN_INFO "ip ah init: can't add xfrm type\n"); 311 return -EAGAIN; 312 } 313 if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) { 314 printk(KERN_INFO "ip ah init: can't add protocol\n"); 315 xfrm_unregister_type(&ah_type, AF_INET); 316 return -EAGAIN; 317 } 318 return 0; 319 } 320 321 static void __exit ah4_fini(void) 322 { 323 if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0) 324 printk(KERN_INFO "ip ah close: can't remove protocol\n"); 325 if (xfrm_unregister_type(&ah_type, AF_INET) < 0) 326 printk(KERN_INFO "ip ah close: can't remove xfrm type\n"); 327 } 328 329 module_init(ah4_init); 330 module_exit(ah4_fini); 331 MODULE_LICENSE("GPL"); 332