net/ipv6/netfilter/ip6t_rt.c

   1 /* Kernel module to match ROUTING parameters. */
   2
   3 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/ipv6.h>
  13 #include <linux/types.h>
  14 #include <net/checksum.h>
  15 #include <net/ipv6.h>
  16
  17 #include <asm/byteorder.h>
  18
  19 #include <linux/netfilter_ipv6/ip6_tables.h>
  20 #include <linux/netfilter_ipv6/ip6t_rt.h>
  21
  22 MODULE_LICENSE("GPL");
  23 MODULE_DESCRIPTION("IPv6 RT match");
  24 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  25
  26 #if 0
  27 #define DEBUGP printk
  28 #else
  29 #define DEBUGP(format, args...)
  30 #endif
  31
  32 /* Returns 1 if the id is matched by the range, 0 otherwise */
  33 static inline int
  34 segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
  35 {
  36        int r=0;
  37        DEBUGP("rt segsleft_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
  38               min,id,max);
  39        r=(id >= min && id <= max) ^ invert;
  40        DEBUGP(" result %s\n",r? "PASS" : "FAILED");
  41        return r;
  42 }
  43
  44 static int
  45 match(const struct sk_buff *skb,
  46       const struct net_device *in,
  47       const struct net_device *out,
  48       const void *matchinfo,
  49       int offset,
  50       unsigned int protoff,
  51       int *hotdrop)
  52 {
  53        struct ipv6_rt_hdr _route, *rh = NULL;
  54        const struct ip6t_rt *rtinfo = matchinfo;
  55        unsigned int temp;
  56        unsigned int len;
  57        u8 nexthdr;
  58        unsigned int ptr;
  59        unsigned int hdrlen = 0;
  60        unsigned int ret = 0;
  61        struct in6_addr *ap, _addr;
  62
  63        /* type of the 1st exthdr */
  64        nexthdr = skb->nh.ipv6h->nexthdr;
  65        /* pointer to the 1st exthdr */
  66        ptr = sizeof(struct ipv6hdr);
  67        /* available length */
  68        len = skb->len - ptr;
  69        temp = 0;
  70
  71         while (ip6t_ext_hdr(nexthdr)) {
  72                struct ipv6_opt_hdr _hdr, *hp;
  73
  74               DEBUGP("ipv6_rt header iteration \n");
  75
  76               /* Is there enough space for the next ext header? */
  77                 if (len < (int)sizeof(struct ipv6_opt_hdr))
  78                         return 0;
  79               /* No more exthdr -> evaluate */
  80                 if (nexthdr == NEXTHDR_NONE) {
  81                      break;
  82               }
  83               /* ESP -> evaluate */
  84                 if (nexthdr == NEXTHDR_ESP) {
  85                      break;
  86               }
  87
  88               hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
  89               BUG_ON(hp == NULL);
  90
  91               /* Calculate the header length */
  92                 if (nexthdr == NEXTHDR_FRAGMENT) {
  93                         hdrlen = 8;
  94                 } else if (nexthdr == NEXTHDR_AUTH)
  95                         hdrlen = (hp->hdrlen+2)<<2;
  96                 else
  97                         hdrlen = ipv6_optlen(hp);
  98
  99               /* ROUTING -> evaluate */
 100                 if (nexthdr == NEXTHDR_ROUTING) {
 101                      temp |= MASK_ROUTING;
 102                      break;
 103               }
 104
 105
 106               /* set the flag */
 107               switch (nexthdr){
 108                      case NEXTHDR_HOP:
 109                      case NEXTHDR_ROUTING:
 110                      case NEXTHDR_FRAGMENT:
 111                      case NEXTHDR_AUTH:
 112                      case NEXTHDR_DEST:
 113                             break;
 114                      default:
 115                             DEBUGP("ipv6_rt match: unknown nextheader %u\n",nexthdr);
 116                             return 0;
 117                             break;
 118               }
 119
 120                 nexthdr = hp->nexthdr;
 121                 len -= hdrlen;
 122                 ptr += hdrlen;
 123                 if ( ptr > skb->len ) {
 124                         DEBUGP("ipv6_rt: new pointer is too large! \n");
 125                         break;
 126                 }
 127         }
 128
 129        /* ROUTING header not found */
 130        if ( temp != MASK_ROUTING ) return 0;
 131
 132        if (len < (int)sizeof(struct ipv6_rt_hdr)){
 133                *hotdrop = 1;
 134                 return 0;
 135        }
 136
 137        if (len < hdrlen){
 138                /* Pcket smaller than its length field */
 139                 return 0;
 140        }
 141
 142        rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
 143        BUG_ON(rh == NULL);
 144
 145        DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
 146        DEBUGP("TYPE %04X ", rh->type);
 147        DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
 148
 149        DEBUGP("IPv6 RT segsleft %02X ",
 150                 (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 151                            rh->segments_left,
 152                            !!(rtinfo->invflags & IP6T_RT_INV_SGS))));
 153        DEBUGP("type %02X %02X %02X ",
 154                 rtinfo->rt_type, rh->type,
 155                 (!(rtinfo->flags & IP6T_RT_TYP) ||
 156                            ((rtinfo->rt_type == rh->type) ^
 157                            !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
 158        DEBUGP("len %02X %04X %02X ",
 159                 rtinfo->hdrlen, hdrlen,
 160                 (!(rtinfo->flags & IP6T_RT_LEN) ||
 161                            ((rtinfo->hdrlen == hdrlen) ^
 162                            !!(rtinfo->invflags & IP6T_RT_INV_LEN))));
 163        DEBUGP("res %02X %02X %02X ",
 164                 (rtinfo->flags & IP6T_RT_RES), ((struct rt0_hdr *)rh)->bitmap,
 165                 !((rtinfo->flags & IP6T_RT_RES) && (((struct rt0_hdr *)rh)->bitmap)));
 166
 167        ret = (rh != NULL)
 168                 &&
 169                 (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 170                            rh->segments_left,
 171                            !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 172                 &&
 173                 (!(rtinfo->flags & IP6T_RT_LEN) ||
 174                            ((rtinfo->hdrlen == hdrlen) ^
 175                            !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 176                 &&
 177                 (!(rtinfo->flags & IP6T_RT_TYP) ||
 178                            ((rtinfo->rt_type == rh->type) ^
 179                            !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 180
 181         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 182                 u_int32_t *bp, _bitmap;
 183                 bp = skb_header_pointer(skb,
 184                                         ptr + offsetof(struct rt0_hdr, bitmap),
 185                                         sizeof(_bitmap), &_bitmap);
 186
 187                 ret = (*bp == 0);
 188         }
 189
 190         DEBUGP("#%d ",rtinfo->addrnr);
 191        if ( !(rtinfo->flags & IP6T_RT_FST) ){
 192                return ret;
 193         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 194                 DEBUGP("Not strict ");
 195                 if ( rtinfo->addrnr > (unsigned int)((hdrlen-8)/16) ){
 196                         DEBUGP("There isn't enough space\n");
 197                         return 0;
 198                 } else {
 199                         unsigned int i = 0;
 200
 201                         DEBUGP("#%d ",rtinfo->addrnr);
 202                         for(temp=0; temp<(unsigned int)((hdrlen-8)/16); temp++){
 203                                 ap = skb_header_pointer(skb,
 204                                                         ptr
 205                                                         + sizeof(struct rt0_hdr)
 206                                                         + temp * sizeof(_addr),
 207                                                         sizeof(_addr),
 208                                                         &_addr);
 209
 210                                 BUG_ON(ap == NULL);
 211
 212                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 213                                         DEBUGP("i=%d temp=%d;\n",i,temp);
 214                                         i++;
 215                                 }
 216                                 if (i==rtinfo->addrnr) break;
 217                         }
 218                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 219                         if (i == rtinfo->addrnr)
 220                                 return ret;
 221                         else return 0;
 222                 }
 223         } else {
 224                 DEBUGP("Strict ");
 225                 if ( rtinfo->addrnr > (unsigned int)((hdrlen-8)/16) ){
 226                         DEBUGP("There isn't enough space\n");
 227                         return 0;
 228                 } else {
 229                         DEBUGP("#%d ",rtinfo->addrnr);
 230                         for(temp=0; temp<rtinfo->addrnr; temp++){
 231                                 ap = skb_header_pointer(skb,
 232                                                         ptr
 233                                                         + sizeof(struct rt0_hdr)
 234                                                         + temp * sizeof(_addr),
 235                                                         sizeof(_addr),
 236                                                         &_addr);
 237                                 BUG_ON(ap == NULL);
 238
 239                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 240                                         break;
 241                         }
 242                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 243                         if ((temp == rtinfo->addrnr) && (temp == (unsigned int)((hdrlen-8)/16)))
 244                                 return ret;
 245                         else return 0;
 246                 }
 247         }
 248
 249         return 0;
 250 }
 251
 252 /* Called when user tries to insert an entry of this type. */
 253 static int
 254 checkentry(const char *tablename,
 255           const struct ip6t_ip6 *ip,
 256           void *matchinfo,
 257           unsigned int matchinfosize,
 258           unsigned int hook_mask)
 259 {
 260        const struct ip6t_rt *rtinfo = matchinfo;
 261
 262        if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_rt))) {
 263               DEBUGP("ip6t_rt: matchsize %u != %u\n",
 264                       matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_rt)));
 265               return 0;
 266        }
 267        if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 268               DEBUGP("ip6t_rt: unknown flags %X\n",
 269                       rtinfo->invflags);
 270               return 0;
 271        }
 272        if ( (rtinfo->flags & (IP6T_RT_RES|IP6T_RT_FST_MASK)) &&
 273                        (!(rtinfo->flags & IP6T_RT_TYP) ||
 274                        (rtinfo->rt_type != 0) ||
 275                        (rtinfo->invflags & IP6T_RT_INV_TYP)) ) {
 276               DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 277               return 0;
 278        }
 279
 280        return 1;
 281 }
 282
 283 static struct ip6t_match rt_match = {
 284         .name           = "rt",
 285         .match          = &match,
 286         .checkentry     = &checkentry,
 287         .me             = THIS_MODULE,
 288 };
 289
 290 static int __init init(void)
 291 {
 292        return ip6t_register_match(&rt_match);
 293 }
 294
 295 static void __exit cleanup(void)
 296 {
 297        ip6t_unregister_match(&rt_match);
 298 }
 299
 300 module_init(init);
 301 module_exit(cleanup);