root/net/inet/route.c

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DEFINITIONS

This source file includes following definitions.
  1. rt_del
  2. ip_rt_flush
  3. default_mask
  4. guess_mask
  5. get_gw_dev
  6. ip_rt_add
  7. bad_mask
  8. rt_new
  9. rt_kill
  10. rt_get_info
  11. ip_rt_route
  12. ip_rt_local
  13. ip_get_old_rtent
  14. ip_rt_ioctl

   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  *              ROUTE - implementation of the IP router.
   7  *
   8  * Version:     @(#)route.c     1.0.14  05/31/93
   9  *
  10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  13  *              Linus Torvalds, <Linus.Torvalds@helsinki.fi>
  14  *
  15  * Fixes:
  16  *              Alan Cox        :       Verify area fixes.
  17  *              Alan Cox        :       cli() protects routing changes
  18  *              Rui Oliveira    :       ICMP routing table updates
  19  *              (rco@di.uminho.pt)      Routing table insertion and update
  20  *              Linus Torvalds  :       Rewrote bits to be sensible
  21  *              Alan Cox        :       Added BSD route gw semantics
  22  *              Alan Cox        :       Super /proc >4K 
  23  *              Alan Cox        :       MTU in route table
  24  *              Alan Cox        :       MSS actually. Also added the window
  25  *                                      clamper.
  26  *              Sam Lantinga    :       Fixed route matching in rt_del()
  27  *
  28  *              This program is free software; you can redistribute it and/or
  29  *              modify it under the terms of the GNU General Public License
  30  *              as published by the Free Software Foundation; either version
  31  *              2 of the License, or (at your option) any later version.
  32  */
  33 
  34 #include <asm/segment.h>
  35 #include <asm/system.h>
  36 #include <linux/types.h>
  37 #include <linux/kernel.h>
  38 #include <linux/sched.h>
  39 #include <linux/mm.h>
  40 #include <linux/string.h>
  41 #include <linux/socket.h>
  42 #include <linux/sockios.h>
  43 #include <linux/errno.h>
  44 #include <linux/in.h>
  45 #include <linux/inet.h>
  46 #include <linux/netdevice.h>
  47 #include "ip.h"
  48 #include "protocol.h"
  49 #include "route.h"
  50 #include "tcp.h"
  51 #include <linux/skbuff.h>
  52 #include "sock.h"
  53 #include "icmp.h"
  54 
  55 /*
  56  *      The routing table list
  57  */
  58 
  59 static struct rtable *rt_base = NULL;
  60 
  61 /*
  62  *      Pointer to the loopback route
  63  */
  64  
  65 static struct rtable *rt_loopback = NULL;
  66 
  67 /*
  68  *      Remove a routing table entry.
  69  */
  70 
  71 static void rt_del(unsigned long dst, char *devname)
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  72 {
  73         struct rtable *r, **rp;
  74         unsigned long flags;
  75 
  76         rp = &rt_base;
  77         
  78         /*
  79          *      This must be done with interrupts off because we could take
  80          *      an ICMP_REDIRECT.
  81          */
  82          
  83         save_flags(flags);
  84         cli();
  85         while((r = *rp) != NULL) 
  86         {
  87                 /* Make sure both the destination and the device match */
  88                 if ( r->rt_dst != dst ||
  89                 (devname != NULL && strcmp((r->rt_dev)->name,devname) != 0) )
  90                 {
  91                         rp = &r->rt_next;
  92                         continue;
  93                 }
  94                 *rp = r->rt_next;
  95                 
  96                 /*
  97                  *      If we delete the loopback route update its pointer.
  98                  */
  99                  
 100                 if (rt_loopback == r)
 101                         rt_loopback = NULL;
 102                 kfree_s(r, sizeof(struct rtable));
 103         } 
 104         restore_flags(flags);
 105 }
 106 
 107 
 108 /*
 109  *      Remove all routing table entries for a device. This is called when
 110  *      a device is downed.
 111  */
 112  
 113 void ip_rt_flush(struct device *dev)
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 114 {
 115         struct rtable *r;
 116         struct rtable **rp;
 117         unsigned long flags;
 118 
 119         rp = &rt_base;
 120         save_flags(flags);
 121         cli();
 122         while ((r = *rp) != NULL) {
 123                 if (r->rt_dev != dev) {
 124                         rp = &r->rt_next;
 125                         continue;
 126                 }
 127                 *rp = r->rt_next;
 128                 if (rt_loopback == r)
 129                         rt_loopback = NULL;
 130                 kfree_s(r, sizeof(struct rtable));
 131         } 
 132         restore_flags(flags);
 133 }
 134 
 135 /*
 136  *      Used by 'rt_add()' when we can't get the netmask any other way..
 137  *
 138  *      If the lower byte or two are zero, we guess the mask based on the
 139  *      number of zero 8-bit net numbers, otherwise we use the "default"
 140  *      masks judging by the destination address and our device netmask.
 141  */
 142  
 143 static inline unsigned long default_mask(unsigned long dst)
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 144 {
 145         dst = ntohl(dst);
 146         if (IN_CLASSA(dst))
 147                 return htonl(IN_CLASSA_NET);
 148         if (IN_CLASSB(dst))
 149                 return htonl(IN_CLASSB_NET);
 150         return htonl(IN_CLASSC_NET);
 151 }
 152 
 153 
 154 /*
 155  *      If no mask is specified then generate a default entry.
 156  */
 157 
 158 static unsigned long guess_mask(unsigned long dst, struct device * dev)
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 159 {
 160         unsigned long mask;
 161 
 162         if (!dst)
 163                 return 0;
 164         mask = default_mask(dst);
 165         if ((dst ^ dev->pa_addr) & mask)
 166                 return mask;
 167         return dev->pa_mask;
 168 }
 169 
 170 
 171 /*
 172  *      Find the route entry through which our gateway will be reached
 173  */
 174  
 175 static inline struct device * get_gw_dev(unsigned long gw)
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 176 {
 177         struct rtable * rt;
 178 
 179         for (rt = rt_base ; ; rt = rt->rt_next) 
 180         {
 181                 if (!rt)
 182                         return NULL;
 183                 if ((gw ^ rt->rt_dst) & rt->rt_mask)
 184                         continue;
 185                 /* 
 186                  *      Gateways behind gateways are a no-no 
 187                  */
 188                  
 189                 if (rt->rt_flags & RTF_GATEWAY)
 190                         return NULL;
 191                 return rt->rt_dev;
 192         }
 193 }
 194 
 195 /*
 196  *      Rewrote rt_add(), as the old one was weird - Linus
 197  *
 198  *      This routine is used to update the IP routing table, either
 199  *      from the kernel (ICMP_REDIRECT) or via an ioctl call issued
 200  *      by the superuser.
 201  */
 202  
 203 void ip_rt_add(short flags, unsigned long dst, unsigned long mask,
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 204         unsigned long gw, struct device *dev, unsigned short mtu, unsigned long window)
 205 {
 206         struct rtable *r, *rt;
 207         struct rtable **rp;
 208         unsigned long cpuflags;
 209 
 210         /*
 211          *      A host is a unique machine and has no network bits.
 212          */
 213          
 214         if (flags & RTF_HOST) 
 215         {
 216                 mask = 0xffffffff;
 217         } 
 218         
 219         /*
 220          *      Calculate the network mask
 221          */
 222          
 223         else if (!mask) 
 224         {
 225                 if (!((dst ^ dev->pa_addr) & dev->pa_mask)) 
 226                 {
 227                         mask = dev->pa_mask;
 228                         flags &= ~RTF_GATEWAY;
 229                         if (flags & RTF_DYNAMIC) 
 230                         {
 231                                 /*printk("Dynamic route to my own net rejected\n");*/
 232                                 return;
 233                         }
 234                 } 
 235                 else
 236                         mask = guess_mask(dst, dev);
 237                 dst &= mask;
 238         }
 239         
 240         /*
 241          *      A gateway must be reachable and not a local address
 242          */
 243          
 244         if (gw == dev->pa_addr)
 245                 flags &= ~RTF_GATEWAY;
 246                 
 247         if (flags & RTF_GATEWAY) 
 248         {
 249                 /*
 250                  *      Don't try to add a gateway we can't reach.. 
 251                  */
 252                  
 253                 if (dev != get_gw_dev(gw))
 254                         return;
 255                         
 256                 flags |= RTF_GATEWAY;
 257         } 
 258         else
 259                 gw = 0;
 260                 
 261         /*
 262          *      Allocate an entry and fill it in.
 263          */
 264          
 265         rt = (struct rtable *) kmalloc(sizeof(struct rtable), GFP_ATOMIC);
 266         if (rt == NULL) 
 267         {
 268                 return;
 269         }
 270         memset(rt, 0, sizeof(struct rtable));
 271         rt->rt_flags = flags | RTF_UP;
 272         rt->rt_dst = dst;
 273         rt->rt_dev = dev;
 274         rt->rt_gateway = gw;
 275         rt->rt_mask = mask;
 276         rt->rt_mss = dev->mtu - HEADER_SIZE;
 277         rt->rt_window = 0;      /* Default is no clamping */
 278 
 279         /* Are the MSS/Window valid ? */
 280 
 281         if(rt->rt_flags & RTF_MSS)
 282                 rt->rt_mss = mtu;
 283                 
 284         if(rt->rt_flags & RTF_WINDOW)
 285                 rt->rt_window = window;
 286 
 287         /*
 288          *      What we have to do is loop though this until we have
 289          *      found the first address which has a higher generality than
 290          *      the one in rt.  Then we can put rt in right before it.
 291          *      The interrupts must be off for this process.
 292          */
 293 
 294         save_flags(cpuflags);
 295         cli();
 296 
 297         /*
 298          *      Remove old route if we are getting a duplicate. 
 299          */
 300          
 301         rp = &rt_base;
 302         while ((r = *rp) != NULL) 
 303         {
 304                 if (r->rt_dst != dst) 
 305                 {
 306                         rp = &r->rt_next;
 307                         continue;
 308                 }
 309                 *rp = r->rt_next;
 310                 if (rt_loopback == r)
 311                         rt_loopback = NULL;
 312                 kfree_s(r, sizeof(struct rtable));
 313         }
 314         
 315         /*
 316          *      Add the new route 
 317          */
 318          
 319         rp = &rt_base;
 320         while ((r = *rp) != NULL) {
 321                 if ((r->rt_mask & mask) != mask)
 322                         break;
 323                 rp = &r->rt_next;
 324         }
 325         rt->rt_next = r;
 326         *rp = rt;
 327         
 328         /*
 329          *      Update the loopback route
 330          */
 331          
 332         if ((rt->rt_dev->flags & IFF_LOOPBACK) && !rt_loopback)
 333                 rt_loopback = rt;
 334                 
 335         /*
 336          *      Restore the interrupts and return
 337          */
 338          
 339         restore_flags(cpuflags);
 340         return;
 341 }
 342 
 343 
 344 /*
 345  *      Check if a mask is acceptable.
 346  */
 347  
 348 static inline int bad_mask(unsigned long mask, unsigned long addr)
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 349 {
 350         if (addr & (mask = ~mask))
 351                 return 1;
 352         mask = ntohl(mask);
 353         if (mask & (mask+1))
 354                 return 1;
 355         return 0;
 356 }
 357 
 358 /*
 359  *      Process a route add request from the user
 360  */
 361  
 362 static int rt_new(struct rtentry *r)
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 363 {
 364         int err;
 365         char * devname;
 366         struct device * dev = NULL;
 367         unsigned long flags, daddr, mask, gw;
 368 
 369         /*
 370          *      If a device is specified find it.
 371          */
 372          
 373         if ((devname = r->rt_dev) != NULL) 
 374         {
 375                 err = getname(devname, &devname);
 376                 if (err)
 377                         return err;
 378                 dev = dev_get(devname);
 379                 putname(devname);
 380                 if (!dev)
 381                         return -EINVAL;
 382         }
 383         
 384         /*
 385          *      If the device isn't INET, don't allow it
 386          */
 387 
 388         if (r->rt_dst.sa_family != AF_INET)
 389                 return -EAFNOSUPPORT;
 390 
 391         /*
 392          *      Make local copies of the important bits
 393          */
 394          
 395         flags = r->rt_flags;
 396         daddr = ((struct sockaddr_in *) &r->rt_dst)->sin_addr.s_addr;
 397         mask = ((struct sockaddr_in *) &r->rt_genmask)->sin_addr.s_addr;
 398         gw = ((struct sockaddr_in *) &r->rt_gateway)->sin_addr.s_addr;
 399 
 400 
 401         /*
 402          *      BSD emulation: Permits route add someroute gw one-of-my-addresses
 403          *      to indicate which iface. Not as clean as the nice Linux dev technique
 404          *      but people keep using it... 
 405          */
 406          
 407         if (!dev && (flags & RTF_GATEWAY)) 
 408         {
 409                 struct device *dev2;
 410                 for (dev2 = dev_base ; dev2 != NULL ; dev2 = dev2->next) 
 411                 {
 412                         if ((dev2->flags & IFF_UP) && dev2->pa_addr == gw) 
 413                         {
 414                                 flags &= ~RTF_GATEWAY;
 415                                 dev = dev2;
 416                                 break;
 417                         }
 418                 }
 419         }
 420 
 421         /*
 422          *      Ignore faulty masks
 423          */
 424          
 425         if (bad_mask(mask, daddr))
 426                 mask = 0;
 427 
 428         /*
 429          *      Set the mask to nothing for host routes.
 430          */
 431          
 432         if (flags & RTF_HOST)
 433                 mask = 0xffffffff;
 434         else if (mask && r->rt_genmask.sa_family != AF_INET)
 435                 return -EAFNOSUPPORT;
 436 
 437         /*
 438          *      You can only gateway IP via IP..
 439          */
 440          
 441         if (flags & RTF_GATEWAY) 
 442         {
 443                 if (r->rt_gateway.sa_family != AF_INET)
 444                         return -EAFNOSUPPORT;
 445                 if (!dev)
 446                         dev = get_gw_dev(gw);
 447         } 
 448         else if (!dev)
 449                 dev = ip_dev_check(daddr);
 450 
 451         /*
 452          *      Unknown device.
 453          */
 454          
 455         if (dev == NULL)
 456                 return -ENETUNREACH;
 457 
 458         /*
 459          *      Add the route
 460          */
 461          
 462         ip_rt_add(flags, daddr, mask, gw, dev, r->rt_mss, r->rt_window);
 463         return 0;
 464 }
 465 
 466 
 467 /*
 468  *      Remove a route, as requested by the user.
 469  */
 470 
 471 static int rt_kill(struct rtentry *r)
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 472 {
 473         struct sockaddr_in *trg;
 474         char *devname;
 475         int err;
 476 
 477         trg = (struct sockaddr_in *) &r->rt_dst;
 478         if ((devname = r->rt_dev) != NULL) 
 479         {
 480                 err = getname(devname, &devname);
 481                 if (err)
 482                         return err;
 483         }
 484         rt_del(trg->sin_addr.s_addr, devname);
 485         if ( devname != NULL )
 486                 putname(devname);
 487         return 0;
 488 }
 489 
 490 
 491 /* 
 492  *      Called from the PROCfs module. This outputs /proc/net/route.
 493  */
 494  
 495 int rt_get_info(char *buffer, char **start, off_t offset, int length)
     /* [previous][next][first][last][top][bottom][index][help] */
 496 {
 497         struct rtable *r;
 498         int len=0;
 499         off_t pos=0;
 500         off_t begin=0;
 501         int size;
 502 
 503         len += sprintf(buffer,
 504                  "Iface\tDestination\tGateway \tFlags\tRefCnt\tUse\tMetric\tMask\t\tMTU\tWindow\n");
 505         pos=len;
 506   
 507         /*
 508          *      This isn't quite right -- r->rt_dst is a struct! 
 509          */
 510          
 511         for (r = rt_base; r != NULL; r = r->rt_next) 
 512         {
 513                 size = sprintf(buffer+len, "%s\t%08lX\t%08lX\t%02X\t%d\t%lu\t%d\t%08lX\t%d\t%lu\n",
 514                         r->rt_dev->name, r->rt_dst, r->rt_gateway,
 515                         r->rt_flags, r->rt_refcnt, r->rt_use, r->rt_metric,
 516                         r->rt_mask, (int)r->rt_mss, r->rt_window);
 517                 len+=size;
 518                 pos+=size;
 519                 if(pos<offset)
 520                 {
 521                         len=0;
 522                         begin=pos;
 523                 }
 524                 if(pos>offset+length)
 525                         break;
 526         }
 527         
 528         *start=buffer+(offset-begin);
 529         len-=(offset-begin);
 530         if(len>length)
 531                 len=length;
 532         return len;
 533 }
 534 
 535 /*
 536  *      This is hackish, but results in better code. Use "-S" to see why.
 537  */
 538  
 539 #define early_out ({ goto no_route; 1; })
 540 
 541 /*
 542  *      Route a packet. This needs to be fairly quick. Florian & Co. 
 543  *      suggested a unified ARP and IP routing cache. Done right its
 544  *      probably a brilliant idea. I'd actually suggest a unified
 545  *      ARP/IP routing/Socket pointer cache. Volunteers welcome
 546  */
 547  
 548 struct rtable * ip_rt_route(unsigned long daddr, struct options *opt, unsigned long *src_addr)
     /* [previous][next][first][last][top][bottom][index][help] */
 549 {
 550         struct rtable *rt;
 551 
 552         for (rt = rt_base; rt != NULL || early_out ; rt = rt->rt_next) 
 553         {
 554                 if (!((rt->rt_dst ^ daddr) & rt->rt_mask))
 555                         break;
 556                 /*
 557                  *      broadcast addresses can be special cases.. 
 558                  */
 559                 if (rt->rt_flags & RTF_GATEWAY)
 560                         continue;                
 561                 if ((rt->rt_dev->flags & IFF_BROADCAST) &&
 562                     (rt->rt_dev->pa_brdaddr == daddr))
 563                         break;
 564         }
 565         
 566         if(src_addr!=NULL)
 567                 *src_addr= rt->rt_dev->pa_addr;
 568                 
 569         if (daddr == rt->rt_dev->pa_addr) {
 570                 if ((rt = rt_loopback) == NULL)
 571                         goto no_route;
 572         }
 573         rt->rt_use++;
 574         return rt;
 575 no_route:
 576         return NULL;
 577 }
 578 
 579 struct rtable * ip_rt_local(unsigned long daddr, struct options *opt, unsigned long *src_addr)
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 580 {
 581         struct rtable *rt;
 582 
 583         for (rt = rt_base; rt != NULL || early_out ; rt = rt->rt_next) 
 584         {
 585                 /*
 586                  *      No routed addressing.
 587                  */
 588                 if (rt->rt_flags&RTF_GATEWAY)
 589                         continue;
 590                         
 591                 if (!((rt->rt_dst ^ daddr) & rt->rt_mask))
 592                         break;
 593                 /*
 594                  *      broadcast addresses can be special cases.. 
 595                  */
 596                  
 597                 if ((rt->rt_dev->flags & IFF_BROADCAST) &&
 598                      rt->rt_dev->pa_brdaddr == daddr)
 599                         break;
 600         }
 601         
 602         if(src_addr!=NULL)
 603                 *src_addr= rt->rt_dev->pa_addr;
 604                 
 605         if (daddr == rt->rt_dev->pa_addr) {
 606                 if ((rt = rt_loopback) == NULL)
 607                         goto no_route;
 608         }
 609         rt->rt_use++;
 610         return rt;
 611 no_route:
 612         return NULL;
 613 }
 614 
 615 /*
 616  *      Backwards compatibility
 617  */
 618  
 619 static int ip_get_old_rtent(struct old_rtentry * src, struct rtentry * rt)
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 620 {
 621         int err;
 622         struct old_rtentry tmp;
 623 
 624         err=verify_area(VERIFY_READ, src, sizeof(*src));
 625         if (err)
 626                 return err;
 627         memcpy_fromfs(&tmp, src, sizeof(*src));
 628         memset(rt, 0, sizeof(*rt));
 629         rt->rt_dst = tmp.rt_dst;
 630         rt->rt_gateway = tmp.rt_gateway;
 631         rt->rt_genmask.sa_family = AF_INET;
 632         ((struct sockaddr_in *) &rt->rt_genmask)->sin_addr.s_addr = tmp.rt_genmask;
 633         rt->rt_flags = tmp.rt_flags;
 634         rt->rt_dev = tmp.rt_dev;
 635         printk("Warning: obsolete routing request made.\n");
 636         return 0;
 637 }
 638 
 639 /*
 640  *      Handle IP routing ioctl calls. These are used to manipulate the routing tables
 641  */
 642  
 643 int ip_rt_ioctl(unsigned int cmd, void *arg)
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 644 {
 645         int err;
 646         struct rtentry rt;
 647 
 648         switch(cmd) 
 649         {
 650                 case SIOCADDRTOLD:      /* Old style add route */
 651                 case SIOCDELRTOLD:      /* Old style delete route */
 652                         if (!suser())
 653                                 return -EPERM;
 654                         err = ip_get_old_rtent((struct old_rtentry *) arg, &rt);
 655                         if (err)
 656                                 return err;
 657                         return (cmd == SIOCDELRTOLD) ? rt_kill(&rt) : rt_new(&rt);
 658 
 659                 case SIOCADDRT:         /* Add a route */
 660                 case SIOCDELRT:         /* Delete a route */
 661                         if (!suser())
 662                                 return -EPERM;
 663                         err=verify_area(VERIFY_READ, arg, sizeof(struct rtentry));
 664                         if (err)
 665                                 return err;
 666                         memcpy_fromfs(&rt, arg, sizeof(struct rtentry));
 667                         return (cmd == SIOCDELRT) ? rt_kill(&rt) : rt_new(&rt);
 668         }
 669 
 670         return -EINVAL;
 671 }

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