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