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",
  38                invert ? '!' : ' ', 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;
  54         const struct ip6t_rt *rtinfo = matchinfo;
  55         unsigned int temp;
  56         unsigned int ptr;
  57         unsigned int hdrlen = 0;
  58         unsigned int ret = 0;
  59         struct in6_addr *ap, _addr;
  60         int err;
  61
  62         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
  63         if (err < 0) {
  64                 if (err != -ENOENT)
  65                         *hotdrop = 1;
  66                 return 0;
  67         }
  68
  69         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  70         if (rh == NULL) {
  71                 *hotdrop = 1;
  72                 return 0;
  73         }
  74
  75         hdrlen = ipv6_optlen(rh);
  76         if (skb->len - ptr < hdrlen) {
  77                 /* Pcket smaller than its length field */
  78                 return 0;
  79         }
  80
  81         DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  82         DEBUGP("TYPE %04X ", rh->type);
  83         DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  84
  85         DEBUGP("IPv6 RT segsleft %02X ",
  86                (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  87                                rh->segments_left,
  88                                !!(rtinfo->invflags & IP6T_RT_INV_SGS))));
  89         DEBUGP("type %02X %02X %02X ",
  90                rtinfo->rt_type, rh->type,
  91                (!(rtinfo->flags & IP6T_RT_TYP) ||
  92                 ((rtinfo->rt_type == rh->type) ^
  93                  !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  94         DEBUGP("len %02X %04X %02X ",
  95                rtinfo->hdrlen, hdrlen,
  96                (!(rtinfo->flags & IP6T_RT_LEN) ||
  97                 ((rtinfo->hdrlen == hdrlen) ^
  98                  !!(rtinfo->invflags & IP6T_RT_INV_LEN))));
  99         DEBUGP("res %02X %02X %02X ",
 100                (rtinfo->flags & IP6T_RT_RES),
 101                ((struct rt0_hdr *)rh)->reserved,
 102                !((rtinfo->flags & IP6T_RT_RES) &&
 103                  (((struct rt0_hdr *)rh)->reserved)));
 104
 105         ret = (rh != NULL)
 106               &&
 107               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 108                               rh->segments_left,
 109                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 110               &&
 111               (!(rtinfo->flags & IP6T_RT_LEN) ||
 112                ((rtinfo->hdrlen == hdrlen) ^
 113                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 114               &&
 115               (!(rtinfo->flags & IP6T_RT_TYP) ||
 116                ((rtinfo->rt_type == rh->type) ^
 117                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 118
 119         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 120                 u_int32_t *rp, _reserved;
 121                 rp = skb_header_pointer(skb,
 122                                         ptr + offsetof(struct rt0_hdr,
 123                                                        reserved),
 124                                         sizeof(_reserved),
 125                                         &_reserved);
 126
 127                 ret = (*rp == 0);
 128         }
 129
 130         DEBUGP("#%d ", rtinfo->addrnr);
 131         if (!(rtinfo->flags & IP6T_RT_FST)) {
 132                 return ret;
 133         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 134                 DEBUGP("Not strict ");
 135                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 136                         DEBUGP("There isn't enough space\n");
 137                         return 0;
 138                 } else {
 139                         unsigned int i = 0;
 140
 141                         DEBUGP("#%d ", rtinfo->addrnr);
 142                         for (temp = 0;
 143                              temp < (unsigned int)((hdrlen - 8) / 16);
 144                              temp++) {
 145                                 ap = skb_header_pointer(skb,
 146                                                         ptr
 147                                                         + sizeof(struct rt0_hdr)
 148                                                         + temp * sizeof(_addr),
 149                                                         sizeof(_addr),
 150                                                         &_addr);
 151
 152                                 BUG_ON(ap == NULL);
 153
 154                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 155                                         DEBUGP("i=%d temp=%d;\n", i, temp);
 156                                         i++;
 157                                 }
 158                                 if (i == rtinfo->addrnr)
 159                                         break;
 160                         }
 161                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 162                         if (i == rtinfo->addrnr)
 163                                 return ret;
 164                         else
 165                                 return 0;
 166                 }
 167         } else {
 168                 DEBUGP("Strict ");
 169                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 170                         DEBUGP("There isn't enough space\n");
 171                         return 0;
 172                 } else {
 173                         DEBUGP("#%d ", rtinfo->addrnr);
 174                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 175                                 ap = skb_header_pointer(skb,
 176                                                         ptr
 177                                                         + sizeof(struct rt0_hdr)
 178                                                         + temp * sizeof(_addr),
 179                                                         sizeof(_addr),
 180                                                         &_addr);
 181                                 BUG_ON(ap == NULL);
 182
 183                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 184                                         break;
 185                         }
 186                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 187                         if ((temp == rtinfo->addrnr) &&
 188                             (temp == (unsigned int)((hdrlen - 8) / 16)))
 189                                 return ret;
 190                         else
 191                                 return 0;
 192                 }
 193         }
 194
 195         return 0;
 196 }
 197
 198 /* Called when user tries to insert an entry of this type. */
 199 static int
 200 checkentry(const char *tablename,
 201            const void *entry,
 202            void *matchinfo,
 203            unsigned int matchinfosize,
 204            unsigned int hook_mask)
 205 {
 206         const struct ip6t_rt *rtinfo = matchinfo;
 207
 208         if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_rt))) {
 209                 DEBUGP("ip6t_rt: matchsize %u != %u\n",
 210                        matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_rt)));
 211                 return 0;
 212         }
 213         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 214                 DEBUGP("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 215                 return 0;
 216         }
 217         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 218             (!(rtinfo->flags & IP6T_RT_TYP) ||
 219              (rtinfo->rt_type != 0) ||
 220              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 221                 DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 222                 return 0;
 223         }
 224
 225         return 1;
 226 }
 227
 228 static struct ip6t_match rt_match = {
 229         .name           = "rt",
 230         .match          = &match,
 231         .checkentry     = &checkentry,
 232         .me             = THIS_MODULE,
 233 };
 234
 235 static int __init init(void)
 236 {
 237         return ip6t_register_match(&rt_match);
 238 }
 239
 240 static void __exit cleanup(void)
 241 {
 242         ip6t_unregister_match(&rt_match);
 243 }
 244
 245 module_init(init);
 246 module_exit(cleanup);