1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * xfrm4_policy.c 4 * 5 * Changes: 6 * Kazunori MIYAZAWA @USAGI 7 * YOSHIFUJI Hideaki @USAGI 8 * Split up af-specific portion 9 * 10 */ 11 12 #include <linux/err.h> 13 #include <linux/kernel.h> 14 #include <linux/inetdevice.h> 15 #include <linux/if_tunnel.h> 16 #include <net/dst.h> 17 #include <net/xfrm.h> 18 #include <net/ip.h> 19 #include <net/l3mdev.h> 20 21 static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4, 22 int tos, int oif, 23 const xfrm_address_t *saddr, 24 const xfrm_address_t *daddr, 25 u32 mark) 26 { 27 struct rtable *rt; 28 29 memset(fl4, 0, sizeof(*fl4)); 30 fl4->daddr = daddr->a4; 31 fl4->flowi4_tos = tos; 32 fl4->flowi4_oif = l3mdev_master_ifindex_by_index(net, oif); 33 fl4->flowi4_mark = mark; 34 if (saddr) 35 fl4->saddr = saddr->a4; 36 37 fl4->flowi4_flags = FLOWI_FLAG_SKIP_NH_OIF; 38 39 rt = __ip_route_output_key(net, fl4); 40 if (!IS_ERR(rt)) 41 return &rt->dst; 42 43 return ERR_CAST(rt); 44 } 45 46 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, int oif, 47 const xfrm_address_t *saddr, 48 const xfrm_address_t *daddr, 49 u32 mark) 50 { 51 struct flowi4 fl4; 52 53 return __xfrm4_dst_lookup(net, &fl4, tos, oif, saddr, daddr, mark); 54 } 55 56 static int xfrm4_get_saddr(struct net *net, int oif, 57 xfrm_address_t *saddr, xfrm_address_t *daddr, 58 u32 mark) 59 { 60 struct dst_entry *dst; 61 struct flowi4 fl4; 62 63 dst = __xfrm4_dst_lookup(net, &fl4, 0, oif, NULL, daddr, mark); 64 if (IS_ERR(dst)) 65 return -EHOSTUNREACH; 66 67 saddr->a4 = fl4.saddr; 68 dst_release(dst); 69 return 0; 70 } 71 72 static int xfrm4_get_tos(const struct flowi *fl) 73 { 74 return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */ 75 } 76 77 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst, 78 int nfheader_len) 79 { 80 return 0; 81 } 82 83 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev, 84 const struct flowi *fl) 85 { 86 struct rtable *rt = (struct rtable *)xdst->route; 87 const struct flowi4 *fl4 = &fl->u.ip4; 88 89 xdst->u.rt.rt_iif = fl4->flowi4_iif; 90 91 xdst->u.dst.dev = dev; 92 dev_hold(dev); 93 94 /* Sheit... I remember I did this right. Apparently, 95 * it was magically lost, so this code needs audit */ 96 xdst->u.rt.rt_is_input = rt->rt_is_input; 97 xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | 98 RTCF_LOCAL); 99 xdst->u.rt.rt_type = rt->rt_type; 100 xdst->u.rt.rt_gateway = rt->rt_gateway; 101 xdst->u.rt.rt_uses_gateway = rt->rt_uses_gateway; 102 xdst->u.rt.rt_pmtu = rt->rt_pmtu; 103 xdst->u.rt.rt_mtu_locked = rt->rt_mtu_locked; 104 INIT_LIST_HEAD(&xdst->u.rt.rt_uncached); 105 rt_add_uncached_list(&xdst->u.rt); 106 107 return 0; 108 } 109 110 static void 111 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 112 { 113 const struct iphdr *iph = ip_hdr(skb); 114 u8 *xprth = skb_network_header(skb) + iph->ihl * 4; 115 struct flowi4 *fl4 = &fl->u.ip4; 116 int oif = 0; 117 118 if (skb_dst(skb)) 119 oif = skb_dst(skb)->dev->ifindex; 120 121 memset(fl4, 0, sizeof(struct flowi4)); 122 fl4->flowi4_mark = skb->mark; 123 fl4->flowi4_oif = reverse ? skb->skb_iif : oif; 124 125 if (!ip_is_fragment(iph)) { 126 switch (iph->protocol) { 127 case IPPROTO_UDP: 128 case IPPROTO_UDPLITE: 129 case IPPROTO_TCP: 130 case IPPROTO_SCTP: 131 case IPPROTO_DCCP: 132 if (xprth + 4 < skb->data || 133 pskb_may_pull(skb, xprth + 4 - skb->data)) { 134 __be16 *ports; 135 136 xprth = skb_network_header(skb) + iph->ihl * 4; 137 ports = (__be16 *)xprth; 138 139 fl4->fl4_sport = ports[!!reverse]; 140 fl4->fl4_dport = ports[!reverse]; 141 } 142 break; 143 144 case IPPROTO_ICMP: 145 if (xprth + 2 < skb->data || 146 pskb_may_pull(skb, xprth + 2 - skb->data)) { 147 u8 *icmp; 148 149 xprth = skb_network_header(skb) + iph->ihl * 4; 150 icmp = xprth; 151 152 fl4->fl4_icmp_type = icmp[0]; 153 fl4->fl4_icmp_code = icmp[1]; 154 } 155 break; 156 157 case IPPROTO_ESP: 158 if (xprth + 4 < skb->data || 159 pskb_may_pull(skb, xprth + 4 - skb->data)) { 160 __be32 *ehdr; 161 162 xprth = skb_network_header(skb) + iph->ihl * 4; 163 ehdr = (__be32 *)xprth; 164 165 fl4->fl4_ipsec_spi = ehdr[0]; 166 } 167 break; 168 169 case IPPROTO_AH: 170 if (xprth + 8 < skb->data || 171 pskb_may_pull(skb, xprth + 8 - skb->data)) { 172 __be32 *ah_hdr; 173 174 xprth = skb_network_header(skb) + iph->ihl * 4; 175 ah_hdr = (__be32 *)xprth; 176 177 fl4->fl4_ipsec_spi = ah_hdr[1]; 178 } 179 break; 180 181 case IPPROTO_COMP: 182 if (xprth + 4 < skb->data || 183 pskb_may_pull(skb, xprth + 4 - skb->data)) { 184 __be16 *ipcomp_hdr; 185 186 xprth = skb_network_header(skb) + iph->ihl * 4; 187 ipcomp_hdr = (__be16 *)xprth; 188 189 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1])); 190 } 191 break; 192 193 case IPPROTO_GRE: 194 if (xprth + 12 < skb->data || 195 pskb_may_pull(skb, xprth + 12 - skb->data)) { 196 __be16 *greflags; 197 __be32 *gre_hdr; 198 199 xprth = skb_network_header(skb) + iph->ihl * 4; 200 greflags = (__be16 *)xprth; 201 gre_hdr = (__be32 *)xprth; 202 203 if (greflags[0] & GRE_KEY) { 204 if (greflags[0] & GRE_CSUM) 205 gre_hdr++; 206 fl4->fl4_gre_key = gre_hdr[1]; 207 } 208 } 209 break; 210 211 default: 212 fl4->fl4_ipsec_spi = 0; 213 break; 214 } 215 } 216 fl4->flowi4_proto = iph->protocol; 217 fl4->daddr = reverse ? iph->saddr : iph->daddr; 218 fl4->saddr = reverse ? iph->daddr : iph->saddr; 219 fl4->flowi4_tos = iph->tos; 220 } 221 222 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk, 223 struct sk_buff *skb, u32 mtu) 224 { 225 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 226 struct dst_entry *path = xdst->route; 227 228 path->ops->update_pmtu(path, sk, skb, mtu); 229 } 230 231 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk, 232 struct sk_buff *skb) 233 { 234 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 235 struct dst_entry *path = xdst->route; 236 237 path->ops->redirect(path, sk, skb); 238 } 239 240 static void xfrm4_dst_destroy(struct dst_entry *dst) 241 { 242 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 243 244 dst_destroy_metrics_generic(dst); 245 if (xdst->u.rt.rt_uncached_list) 246 rt_del_uncached_list(&xdst->u.rt); 247 xfrm_dst_destroy(xdst); 248 } 249 250 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev, 251 int unregister) 252 { 253 if (!unregister) 254 return; 255 256 xfrm_dst_ifdown(dst, dev); 257 } 258 259 static struct dst_ops xfrm4_dst_ops_template = { 260 .family = AF_INET, 261 .update_pmtu = xfrm4_update_pmtu, 262 .redirect = xfrm4_redirect, 263 .cow_metrics = dst_cow_metrics_generic, 264 .destroy = xfrm4_dst_destroy, 265 .ifdown = xfrm4_dst_ifdown, 266 .local_out = __ip_local_out, 267 .gc_thresh = 32768, 268 }; 269 270 static const struct xfrm_policy_afinfo xfrm4_policy_afinfo = { 271 .dst_ops = &xfrm4_dst_ops_template, 272 .dst_lookup = xfrm4_dst_lookup, 273 .get_saddr = xfrm4_get_saddr, 274 .decode_session = _decode_session4, 275 .get_tos = xfrm4_get_tos, 276 .init_path = xfrm4_init_path, 277 .fill_dst = xfrm4_fill_dst, 278 .blackhole_route = ipv4_blackhole_route, 279 }; 280 281 #ifdef CONFIG_SYSCTL 282 static struct ctl_table xfrm4_policy_table[] = { 283 { 284 .procname = "xfrm4_gc_thresh", 285 .data = &init_net.xfrm.xfrm4_dst_ops.gc_thresh, 286 .maxlen = sizeof(int), 287 .mode = 0644, 288 .proc_handler = proc_dointvec, 289 }, 290 { } 291 }; 292 293 static __net_init int xfrm4_net_sysctl_init(struct net *net) 294 { 295 struct ctl_table *table; 296 struct ctl_table_header *hdr; 297 298 table = xfrm4_policy_table; 299 if (!net_eq(net, &init_net)) { 300 table = kmemdup(table, sizeof(xfrm4_policy_table), GFP_KERNEL); 301 if (!table) 302 goto err_alloc; 303 304 table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh; 305 } 306 307 hdr = register_net_sysctl(net, "net/ipv4", table); 308 if (!hdr) 309 goto err_reg; 310 311 net->ipv4.xfrm4_hdr = hdr; 312 return 0; 313 314 err_reg: 315 if (!net_eq(net, &init_net)) 316 kfree(table); 317 err_alloc: 318 return -ENOMEM; 319 } 320 321 static __net_exit void xfrm4_net_sysctl_exit(struct net *net) 322 { 323 struct ctl_table *table; 324 325 if (!net->ipv4.xfrm4_hdr) 326 return; 327 328 table = net->ipv4.xfrm4_hdr->ctl_table_arg; 329 unregister_net_sysctl_table(net->ipv4.xfrm4_hdr); 330 if (!net_eq(net, &init_net)) 331 kfree(table); 332 } 333 #else /* CONFIG_SYSCTL */ 334 static inline int xfrm4_net_sysctl_init(struct net *net) 335 { 336 return 0; 337 } 338 339 static inline void xfrm4_net_sysctl_exit(struct net *net) 340 { 341 } 342 #endif 343 344 static int __net_init xfrm4_net_init(struct net *net) 345 { 346 int ret; 347 348 memcpy(&net->xfrm.xfrm4_dst_ops, &xfrm4_dst_ops_template, 349 sizeof(xfrm4_dst_ops_template)); 350 ret = dst_entries_init(&net->xfrm.xfrm4_dst_ops); 351 if (ret) 352 return ret; 353 354 ret = xfrm4_net_sysctl_init(net); 355 if (ret) 356 dst_entries_destroy(&net->xfrm.xfrm4_dst_ops); 357 358 return ret; 359 } 360 361 static void __net_exit xfrm4_net_exit(struct net *net) 362 { 363 xfrm4_net_sysctl_exit(net); 364 dst_entries_destroy(&net->xfrm.xfrm4_dst_ops); 365 } 366 367 static struct pernet_operations __net_initdata xfrm4_net_ops = { 368 .init = xfrm4_net_init, 369 .exit = xfrm4_net_exit, 370 }; 371 372 static void __init xfrm4_policy_init(void) 373 { 374 xfrm_policy_register_afinfo(&xfrm4_policy_afinfo, AF_INET); 375 } 376 377 void __init xfrm4_init(void) 378 { 379 xfrm4_state_init(); 380 xfrm4_policy_init(); 381 xfrm4_protocol_init(); 382 register_pernet_subsys(&xfrm4_net_ops); 383 } 384