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 sk_buff *skb) 120 { 121 int ah_hlen; 122 int ihl; 123 struct iphdr *iph; 124 struct ip_auth_hdr *ah; 125 struct ah_data *ahp; 126 char work_buf[60]; 127 128 if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr))) 129 goto out; 130 131 ah = (struct ip_auth_hdr*)skb->data; 132 ahp = x->data; 133 ah_hlen = (ah->hdrlen + 2) << 2; 134 135 if (ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_full_len) && 136 ah_hlen != XFRM_ALIGN8(sizeof(struct ip_auth_hdr) + ahp->icv_trunc_len)) 137 goto out; 138 139 if (!pskb_may_pull(skb, ah_hlen)) 140 goto out; 141 142 /* We are going to _remove_ AH header to keep sockets happy, 143 * so... Later this can change. */ 144 if (skb_cloned(skb) && 145 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) 146 goto out; 147 148 skb->ip_summed = CHECKSUM_NONE; 149 150 ah = (struct ip_auth_hdr*)skb->data; 151 iph = skb->nh.iph; 152 153 ihl = skb->data - skb->nh.raw; 154 memcpy(work_buf, iph, ihl); 155 156 iph->ttl = 0; 157 iph->tos = 0; 158 iph->frag_off = 0; 159 iph->check = 0; 160 if (ihl > sizeof(*iph)) { 161 u32 dummy; 162 if (ip_clear_mutable_options(iph, &dummy)) 163 goto out; 164 } 165 { 166 u8 auth_data[MAX_AH_AUTH_LEN]; 167 168 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len); 169 skb_push(skb, ihl); 170 ahp->icv(ahp, skb, ah->auth_data); 171 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) { 172 x->stats.integrity_failed++; 173 goto out; 174 } 175 } 176 ((struct iphdr*)work_buf)->protocol = ah->nexthdr; 177 skb->h.raw = memcpy(skb->nh.raw += ah_hlen, work_buf, ihl); 178 __skb_pull(skb, ah_hlen + ihl); 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 } 203 204 static int ah_init_state(struct xfrm_state *x) 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) { 267 kfree(ahp->work_icv); 268 crypto_free_tfm(ahp->tfm); 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; 280 281 kfree(ahp->work_icv); 282 ahp->work_icv = NULL; 283 crypto_free_tfm(ahp->tfm); 284 ahp->tfm = NULL; 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"); 331