net/ipv4/fib_rules.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IPv4 Forwarding Information Base: policy rules.
   7  *
   8  * Version:     $Id: fib_rules.c,v 1.17 2001/10/31 21:55:54 davem Exp $
   9  *
  10  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  11  *
  12  *              This program is free software; you can redistribute it and/or
  13  *              modify it under the terms of the GNU General Public License
  14  *              as published by the Free Software Foundation; either version
  15  *              2 of the License, or (at your option) any later version.
  16  *
  17  * Fixes:
  18  *              Rani Assaf      :       local_rule cannot be deleted
  19  *              Marc Boucher    :       routing by fwmark
  20  */
  21
  22 #include <linux/config.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/system.h>
  25 #include <linux/bitops.h>
  26 #include <linux/types.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/mm.h>
  30 #include <linux/string.h>
  31 #include <linux/socket.h>
  32 #include <linux/sockios.h>
  33 #include <linux/errno.h>
  34 #include <linux/in.h>
  35 #include <linux/inet.h>
  36 #include <linux/inetdevice.h>
  37 #include <linux/netdevice.h>
  38 #include <linux/if_arp.h>
  39 #include <linux/proc_fs.h>
  40 #include <linux/skbuff.h>
  41 #include <linux/netlink.h>
  42 #include <linux/init.h>
  43 #include <linux/list.h>
  44 #include <linux/rcupdate.h>
  45
  46 #include <net/ip.h>
  47 #include <net/protocol.h>
  48 #include <net/route.h>
  49 #include <net/tcp.h>
  50 #include <net/sock.h>
  51 #include <net/ip_fib.h>
  52
  53 #define FRprintk(a...)
  54
  55 struct fib_rule
  56 {
  57         struct hlist_node hlist;
  58         atomic_t        r_clntref;
  59         u32             r_preference;
  60         unsigned char   r_table;
  61         unsigned char   r_action;
  62         unsigned char   r_dst_len;
  63         unsigned char   r_src_len;
  64         u32             r_src;
  65         u32             r_srcmask;
  66         u32             r_dst;
  67         u32             r_dstmask;
  68         u32             r_srcmap;
  69         u8              r_flags;
  70         u8              r_tos;
  71 #ifdef CONFIG_IP_ROUTE_FWMARK
  72         u32             r_fwmark;
  73 #endif
  74         int             r_ifindex;
  75 #ifdef CONFIG_NET_CLS_ROUTE
  76         __u32           r_tclassid;
  77 #endif
  78         char            r_ifname[IFNAMSIZ];
  79         int             r_dead;
  80         struct          rcu_head rcu;
  81 };
  82
  83 static struct fib_rule default_rule = {
  84         .r_clntref =    ATOMIC_INIT(2),
  85         .r_preference = 0x7FFF,
  86         .r_table =      RT_TABLE_DEFAULT,
  87         .r_action =     RTN_UNICAST,
  88 };
  89
  90 static struct fib_rule main_rule = {
  91         .r_clntref =    ATOMIC_INIT(2),
  92         .r_preference = 0x7FFE,
  93         .r_table =      RT_TABLE_MAIN,
  94         .r_action =     RTN_UNICAST,
  95 };
  96
  97 static struct fib_rule local_rule = {
  98         .r_clntref =    ATOMIC_INIT(2),
  99         .r_table =      RT_TABLE_LOCAL,
 100         .r_action =     RTN_UNICAST,
 101 };
 102
 103 static struct hlist_head fib_rules;
 104
 105 /* writer func called from netlink -- rtnl_sem hold*/
 106
 107 static void rtmsg_rule(int, struct fib_rule *);
 108
 109 int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 110 {
 111         struct rtattr **rta = arg;
 112         struct rtmsg *rtm = NLMSG_DATA(nlh);
 113         struct fib_rule *r;
 114         struct hlist_node *node;
 115         int err = -ESRCH;
 116
 117         hlist_for_each_entry(r, node, &fib_rules, hlist) {
 118                 if ((!rta[RTA_SRC-1] || memcmp(RTA_DATA(rta[RTA_SRC-1]), &r->r_src, 4) == 0) &&
 119                     rtm->rtm_src_len == r->r_src_len &&
 120                     rtm->rtm_dst_len == r->r_dst_len &&
 121                     (!rta[RTA_DST-1] || memcmp(RTA_DATA(rta[RTA_DST-1]), &r->r_dst, 4) == 0) &&
 122                     rtm->rtm_tos == r->r_tos &&
 123 #ifdef CONFIG_IP_ROUTE_FWMARK
 124                     (!rta[RTA_PROTOINFO-1] || memcmp(RTA_DATA(rta[RTA_PROTOINFO-1]), &r->r_fwmark, 4) == 0) &&
 125 #endif
 126                     (!rtm->rtm_type || rtm->rtm_type == r->r_action) &&
 127                     (!rta[RTA_PRIORITY-1] || memcmp(RTA_DATA(rta[RTA_PRIORITY-1]), &r->r_preference, 4) == 0) &&
 128                     (!rta[RTA_IIF-1] || rtattr_strcmp(rta[RTA_IIF-1], r->r_ifname) == 0) &&
 129                     (!rtm->rtm_table || (r && rtm->rtm_table == r->r_table))) {
 130                         err = -EPERM;
 131                         if (r == &local_rule)
 132                                 break;
 133
 134                         hlist_del_rcu(&r->hlist);
 135                         r->r_dead = 1;
 136                         rtmsg_rule(RTM_DELRULE, r);
 137                         fib_rule_put(r);
 138                         err = 0;
 139                         break;
 140                 }
 141         }
 142         return err;
 143 }
 144
 145 /* Allocate new unique table id */
 146
 147 static struct fib_table *fib_empty_table(void)
 148 {
 149         int id;
 150
 151         for (id = 1; id <= RT_TABLE_MAX; id++)
 152                 if (fib_tables[id] == NULL)
 153                         return __fib_new_table(id);
 154         return NULL;
 155 }
 156
 157 static inline void fib_rule_put_rcu(struct rcu_head *head)
 158 {
 159         struct fib_rule *r = container_of(head, struct fib_rule, rcu);
 160         kfree(r);
 161 }
 162
 163 void fib_rule_put(struct fib_rule *r)
 164 {
 165         if (atomic_dec_and_test(&r->r_clntref)) {
 166                 if (r->r_dead)
 167                         call_rcu(&r->rcu, fib_rule_put_rcu);
 168                 else
 169                         printk("Freeing alive rule %p\n", r);
 170         }
 171 }
 172
 173 /* writer func called from netlink -- rtnl_sem hold*/
 174
 175 int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 176 {
 177         struct rtattr **rta = arg;
 178         struct rtmsg *rtm = NLMSG_DATA(nlh);
 179         struct fib_rule *r, *new_r, *last = NULL;
 180         struct hlist_node *node = NULL;
 181         unsigned char table_id;
 182
 183         if (rtm->rtm_src_len > 32 || rtm->rtm_dst_len > 32 ||
 184             (rtm->rtm_tos & ~IPTOS_TOS_MASK))
 185                 return -EINVAL;
 186
 187         if (rta[RTA_IIF-1] && RTA_PAYLOAD(rta[RTA_IIF-1]) > IFNAMSIZ)
 188                 return -EINVAL;
 189
 190         table_id = rtm->rtm_table;
 191         if (table_id == RT_TABLE_UNSPEC) {
 192                 struct fib_table *table;
 193                 if (rtm->rtm_type == RTN_UNICAST) {
 194                         if ((table = fib_empty_table()) == NULL)
 195                                 return -ENOBUFS;
 196                         table_id = table->tb_id;
 197                 }
 198         }
 199
 200         new_r = kmalloc(sizeof(*new_r), GFP_KERNEL);
 201         if (!new_r)
 202                 return -ENOMEM;
 203         memset(new_r, 0, sizeof(*new_r));
 204
 205         if (rta[RTA_SRC-1])
 206                 memcpy(&new_r->r_src, RTA_DATA(rta[RTA_SRC-1]), 4);
 207         if (rta[RTA_DST-1])
 208                 memcpy(&new_r->r_dst, RTA_DATA(rta[RTA_DST-1]), 4);
 209         if (rta[RTA_GATEWAY-1])
 210                 memcpy(&new_r->r_srcmap, RTA_DATA(rta[RTA_GATEWAY-1]), 4);
 211         new_r->r_src_len = rtm->rtm_src_len;
 212         new_r->r_dst_len = rtm->rtm_dst_len;
 213         new_r->r_srcmask = inet_make_mask(rtm->rtm_src_len);
 214         new_r->r_dstmask = inet_make_mask(rtm->rtm_dst_len);
 215         new_r->r_tos = rtm->rtm_tos;
 216 #ifdef CONFIG_IP_ROUTE_FWMARK
 217         if (rta[RTA_PROTOINFO-1])
 218                 memcpy(&new_r->r_fwmark, RTA_DATA(rta[RTA_PROTOINFO-1]), 4);
 219 #endif
 220         new_r->r_action = rtm->rtm_type;
 221         new_r->r_flags = rtm->rtm_flags;
 222         if (rta[RTA_PRIORITY-1])
 223                 memcpy(&new_r->r_preference, RTA_DATA(rta[RTA_PRIORITY-1]), 4);
 224         new_r->r_table = table_id;
 225         if (rta[RTA_IIF-1]) {
 226                 struct net_device *dev;
 227                 rtattr_strlcpy(new_r->r_ifname, rta[RTA_IIF-1], IFNAMSIZ);
 228                 new_r->r_ifindex = -1;
 229                 dev = __dev_get_by_name(new_r->r_ifname);
 230                 if (dev)
 231                         new_r->r_ifindex = dev->ifindex;
 232         }
 233 #ifdef CONFIG_NET_CLS_ROUTE
 234         if (rta[RTA_FLOW-1])
 235                 memcpy(&new_r->r_tclassid, RTA_DATA(rta[RTA_FLOW-1]), 4);
 236 #endif
 237         r = container_of(fib_rules.first, struct fib_rule, hlist);
 238
 239         if (!new_r->r_preference) {
 240                 if (r && r->hlist.next != NULL) {
 241                         r = container_of(r->hlist.next, struct fib_rule, hlist);
 242                         if (r->r_preference)
 243                                 new_r->r_preference = r->r_preference - 1;
 244                 }
 245         }
 246
 247         hlist_for_each_entry(r, node, &fib_rules, hlist) {
 248                 if (r->r_preference > new_r->r_preference)
 249                         break;
 250                 last = r;
 251         }
 252         atomic_inc(&new_r->r_clntref);
 253
 254         if (last)
 255                 hlist_add_after_rcu(&last->hlist, &new_r->hlist);
 256         else
 257                 hlist_add_before_rcu(&new_r->hlist, &r->hlist);
 258
 259         rtmsg_rule(RTM_NEWRULE, new_r);
 260         return 0;
 261 }
 262
 263 #ifdef CONFIG_NET_CLS_ROUTE
 264 u32 fib_rules_tclass(struct fib_result *res)
 265 {
 266         if (res->r)
 267                 return res->r->r_tclassid;
 268         return 0;
 269 }
 270 #endif
 271
 272 /* callers should hold rtnl semaphore */
 273
 274 static void fib_rules_detach(struct net_device *dev)
 275 {
 276         struct hlist_node *node;
 277         struct fib_rule *r;
 278
 279         hlist_for_each_entry(r, node, &fib_rules, hlist) {
 280                 if (r->r_ifindex == dev->ifindex)
 281                         r->r_ifindex = -1;
 282
 283         }
 284 }
 285
 286 /* callers should hold rtnl semaphore */
 287
 288 static void fib_rules_attach(struct net_device *dev)
 289 {
 290         struct hlist_node *node;
 291         struct fib_rule *r;
 292
 293         hlist_for_each_entry(r, node, &fib_rules, hlist) {
 294                 if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0)
 295                         r->r_ifindex = dev->ifindex;
 296         }
 297 }
 298
 299 int fib_lookup(const struct flowi *flp, struct fib_result *res)
 300 {
 301         int err;
 302         struct fib_rule *r, *policy;
 303         struct fib_table *tb;
 304         struct hlist_node *node;
 305
 306         u32 daddr = flp->fl4_dst;
 307         u32 saddr = flp->fl4_src;
 308
 309 FRprintk("Lookup: %u.%u.%u.%u <- %u.%u.%u.%u ",
 310         NIPQUAD(flp->fl4_dst), NIPQUAD(flp->fl4_src));
 311
 312         rcu_read_lock();
 313
 314         hlist_for_each_entry_rcu(r, node, &fib_rules, hlist) {
 315                 if (((saddr^r->r_src) & r->r_srcmask) ||
 316                     ((daddr^r->r_dst) & r->r_dstmask) ||
 317                     (r->r_tos && r->r_tos != flp->fl4_tos) ||
 318 #ifdef CONFIG_IP_ROUTE_FWMARK
 319                     (r->r_fwmark && r->r_fwmark != flp->fl4_fwmark) ||
 320 #endif
 321                     (r->r_ifindex && r->r_ifindex != flp->iif))
 322                         continue;
 323
 324 FRprintk("tb %d r %d ", r->r_table, r->r_action);
 325                 switch (r->r_action) {
 326                 case RTN_UNICAST:
 327                         policy = r;
 328                         break;
 329                 case RTN_UNREACHABLE:
 330                         rcu_read_unlock();
 331                         return -ENETUNREACH;
 332                 default:
 333                 case RTN_BLACKHOLE:
 334                         rcu_read_unlock();
 335                         return -EINVAL;
 336                 case RTN_PROHIBIT:
 337                         rcu_read_unlock();
 338                         return -EACCES;
 339                 }
 340
 341                 if ((tb = fib_get_table(r->r_table)) == NULL)
 342                         continue;
 343                 err = tb->tb_lookup(tb, flp, res);
 344                 if (err == 0) {
 345                         res->r = policy;
 346                         if (policy)
 347                                 atomic_inc(&policy->r_clntref);
 348                         rcu_read_unlock();
 349                         return 0;
 350                 }
 351                 if (err < 0 && err != -EAGAIN) {
 352                         rcu_read_unlock();
 353                         return err;
 354                 }
 355         }
 356 FRprintk("FAILURE\n");
 357         rcu_read_unlock();
 358         return -ENETUNREACH;
 359 }
 360
 361 void fib_select_default(const struct flowi *flp, struct fib_result *res)
 362 {
 363         if (res->r && res->r->r_action == RTN_UNICAST &&
 364             FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) {
 365                 struct fib_table *tb;
 366                 if ((tb = fib_get_table(res->r->r_table)) != NULL)
 367                         tb->tb_select_default(tb, flp, res);
 368         }
 369 }
 370
 371 static int fib_rules_event(struct notifier_block *this, unsigned long event, void *ptr)
 372 {
 373         struct net_device *dev = ptr;
 374
 375         if (event == NETDEV_UNREGISTER)
 376                 fib_rules_detach(dev);
 377         else if (event == NETDEV_REGISTER)
 378                 fib_rules_attach(dev);
 379         return NOTIFY_DONE;
 380 }
 381
 382
 383 static struct notifier_block fib_rules_notifier = {
 384         .notifier_call =fib_rules_event,
 385 };
 386
 387 static __inline__ int inet_fill_rule(struct sk_buff *skb,
 388                                      struct fib_rule *r,
 389                                      u32 pid, u32 seq, int event,
 390                                      unsigned int flags)
 391 {
 392         struct rtmsg *rtm;
 393         struct nlmsghdr  *nlh;
 394         unsigned char    *b = skb->tail;
 395
 396         nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*rtm), flags);
 397         rtm = NLMSG_DATA(nlh);
 398         rtm->rtm_family = AF_INET;
 399         rtm->rtm_dst_len = r->r_dst_len;
 400         rtm->rtm_src_len = r->r_src_len;
 401         rtm->rtm_tos = r->r_tos;
 402 #ifdef CONFIG_IP_ROUTE_FWMARK
 403         if (r->r_fwmark)
 404                 RTA_PUT(skb, RTA_PROTOINFO, 4, &r->r_fwmark);
 405 #endif
 406         rtm->rtm_table = r->r_table;
 407         rtm->rtm_protocol = 0;
 408         rtm->rtm_scope = 0;
 409         rtm->rtm_type = r->r_action;
 410         rtm->rtm_flags = r->r_flags;
 411
 412         if (r->r_dst_len)
 413                 RTA_PUT(skb, RTA_DST, 4, &r->r_dst);
 414         if (r->r_src_len)
 415                 RTA_PUT(skb, RTA_SRC, 4, &r->r_src);
 416         if (r->r_ifname[0])
 417                 RTA_PUT(skb, RTA_IIF, IFNAMSIZ, &r->r_ifname);
 418         if (r->r_preference)
 419                 RTA_PUT(skb, RTA_PRIORITY, 4, &r->r_preference);
 420         if (r->r_srcmap)
 421                 RTA_PUT(skb, RTA_GATEWAY, 4, &r->r_srcmap);
 422 #ifdef CONFIG_NET_CLS_ROUTE
 423         if (r->r_tclassid)
 424                 RTA_PUT(skb, RTA_FLOW, 4, &r->r_tclassid);
 425 #endif
 426         nlh->nlmsg_len = skb->tail - b;
 427         return skb->len;
 428
 429 nlmsg_failure:
 430 rtattr_failure:
 431         skb_trim(skb, b - skb->data);
 432         return -1;
 433 }
 434
 435 /* callers should hold rtnl semaphore */
 436
 437 static void rtmsg_rule(int event, struct fib_rule *r)
 438 {
 439         int size = NLMSG_SPACE(sizeof(struct rtmsg) + 128);
 440         struct sk_buff *skb = alloc_skb(size, GFP_KERNEL);
 441
 442         if (!skb)
 443                 netlink_set_err(rtnl, 0, RTNLGRP_IPV4_RULE, ENOBUFS);
 444         else if (inet_fill_rule(skb, r, 0, 0, event, 0) < 0) {
 445                 kfree_skb(skb);
 446                 netlink_set_err(rtnl, 0, RTNLGRP_IPV4_RULE, EINVAL);
 447         } else {
 448                 netlink_broadcast(rtnl, skb, 0, RTNLGRP_IPV4_RULE, GFP_KERNEL);
 449         }
 450 }
 451
 452 int inet_dump_rules(struct sk_buff *skb, struct netlink_callback *cb)
 453 {
 454         int idx = 0;
 455         int s_idx = cb->args[0];
 456         struct fib_rule *r;
 457         struct hlist_node *node;
 458
 459         rcu_read_lock();
 460         hlist_for_each_entry(r, node, &fib_rules, hlist) {
 461                 if (idx < s_idx)
 462                         goto next;
 463                 if (inet_fill_rule(skb, r, NETLINK_CB(cb->skb).pid,
 464                                    cb->nlh->nlmsg_seq,
 465                                    RTM_NEWRULE, NLM_F_MULTI) < 0)
 466                         break;
 467 next:
 468                 idx++;
 469         }
 470         rcu_read_unlock();
 471         cb->args[0] = idx;
 472
 473         return skb->len;
 474 }
 475
 476 void __init fib_rules_init(void)
 477 {
 478         INIT_HLIST_HEAD(&fib_rules);
 479         hlist_add_head(&local_rule.hlist, &fib_rules);
 480         hlist_add_after(&local_rule.hlist, &main_rule.hlist);
 481         hlist_add_after(&main_rule.hlist, &default_rule.hlist);
 482         register_netdevice_notifier(&fib_rules_notifier);
 483 }