git.oblomov.eu Git - linux-2.6/blob - 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/x_tables.h>
  20 #include <linux/netfilter_ipv6/ip6_tables.h>
  21 #include <linux/netfilter_ipv6/ip6t_rt.h>
  22
  23 MODULE_LICENSE("GPL");
  24 MODULE_DESCRIPTION("IPv6 RT match");
  25 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  26
  27 #if 0
  28 #define DEBUGP printk
  29 #else
  30 #define DEBUGP(format, args...)
  31 #endif
  32
  33 /* Returns 1 if the id is matched by the range, 0 otherwise */
  34 static inline bool
  35 segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
  36 {
  37         bool r;
  38         DEBUGP("rt segsleft_match:%c 0x%x <= 0x%x <= 0x%x",
  39                invert ? '!' : ' ', min, id, max);
  40         r = (id >= min && id <= max) ^ invert;
  41         DEBUGP(" result %s\n", r ? "PASS" : "FAILED");
  42         return r;
  43 }
  44
  45 static bool
  46 match(const struct sk_buff *skb,
  47       const struct net_device *in,
  48       const struct net_device *out,
  49       const struct xt_match *match,
  50       const void *matchinfo,
  51       int offset,
  52       unsigned int protoff,
  53       bool *hotdrop)
  54 {
  55         struct ipv6_rt_hdr _route;
  56         const struct ipv6_rt_hdr *rh;
  57         const struct ip6t_rt *rtinfo = matchinfo;
  58         unsigned int temp;
  59         unsigned int ptr;
  60         unsigned int hdrlen = 0;
  61         bool ret = false;
  62         struct in6_addr _addr;
  63         const struct in6_addr *ap;
  64         int err;
  65
  66         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
  67         if (err < 0) {
  68                 if (err != -ENOENT)
  69                         *hotdrop = true;
  70                 return false;
  71         }
  72
  73         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  74         if (rh == NULL) {
  75                 *hotdrop = true;
  76                 return false;
  77         }
  78
  79         hdrlen = ipv6_optlen(rh);
  80         if (skb->len - ptr < hdrlen) {
  81                 /* Pcket smaller than its length field */
  82                 return false;
  83         }
  84
  85         DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  86         DEBUGP("TYPE %04X ", rh->type);
  87         DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  88
  89         DEBUGP("IPv6 RT segsleft %02X ",
  90                segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  91                               rh->segments_left,
  92                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)));
  93         DEBUGP("type %02X %02X %02X ",
  94                rtinfo->rt_type, rh->type,
  95                (!(rtinfo->flags & IP6T_RT_TYP) ||
  96                 ((rtinfo->rt_type == rh->type) ^
  97                  !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  98         DEBUGP("len %02X %04X %02X ",
  99                rtinfo->hdrlen, hdrlen,
 100                !(rtinfo->flags & IP6T_RT_LEN) ||
 101                 ((rtinfo->hdrlen == hdrlen) ^
 102                  !!(rtinfo->invflags & IP6T_RT_INV_LEN)));
 103         DEBUGP("res %02X %02X %02X ",
 104                rtinfo->flags & IP6T_RT_RES,
 105                ((const struct rt0_hdr *)rh)->reserved,
 106                !((rtinfo->flags & IP6T_RT_RES) &&
 107                  (((const struct rt0_hdr *)rh)->reserved)));
 108
 109         ret = (rh != NULL)
 110               &&
 111               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 112                               rh->segments_left,
 113                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 114               &&
 115               (!(rtinfo->flags & IP6T_RT_LEN) ||
 116                ((rtinfo->hdrlen == hdrlen) ^
 117                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 118               &&
 119               (!(rtinfo->flags & IP6T_RT_TYP) ||
 120                ((rtinfo->rt_type == rh->type) ^
 121                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 122
 123         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 124                 u_int32_t *rp, _reserved;
 125                 rp = skb_header_pointer(skb,
 126                                         ptr + offsetof(struct rt0_hdr,
 127                                                        reserved),
 128                                         sizeof(_reserved),
 129                                         &_reserved);
 130
 131                 ret = (*rp == 0);
 132         }
 133
 134         DEBUGP("#%d ", rtinfo->addrnr);
 135         if (!(rtinfo->flags & IP6T_RT_FST)) {
 136                 return ret;
 137         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 138                 DEBUGP("Not strict ");
 139                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 140                         DEBUGP("There isn't enough space\n");
 141                         return false;
 142                 } else {
 143                         unsigned int i = 0;
 144
 145                         DEBUGP("#%d ", rtinfo->addrnr);
 146                         for (temp = 0;
 147                              temp < (unsigned int)((hdrlen - 8) / 16);
 148                              temp++) {
 149                                 ap = skb_header_pointer(skb,
 150                                                         ptr
 151                                                         + sizeof(struct rt0_hdr)
 152                                                         + temp * sizeof(_addr),
 153                                                         sizeof(_addr),
 154                                                         &_addr);
 155
 156                                 BUG_ON(ap == NULL);
 157
 158                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 159                                         DEBUGP("i=%d temp=%d;\n", i, temp);
 160                                         i++;
 161                                 }
 162                                 if (i == rtinfo->addrnr)
 163                                         break;
 164                         }
 165                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 166                         if (i == rtinfo->addrnr)
 167                                 return ret;
 168                         else
 169                                 return false;
 170                 }
 171         } else {
 172                 DEBUGP("Strict ");
 173                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 174                         DEBUGP("There isn't enough space\n");
 175                         return false;
 176                 } else {
 177                         DEBUGP("#%d ", rtinfo->addrnr);
 178                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 179                                 ap = skb_header_pointer(skb,
 180                                                         ptr
 181                                                         + sizeof(struct rt0_hdr)
 182                                                         + temp * sizeof(_addr),
 183                                                         sizeof(_addr),
 184                                                         &_addr);
 185                                 BUG_ON(ap == NULL);
 186
 187                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 188                                         break;
 189                         }
 190                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 191                         if (temp == rtinfo->addrnr &&
 192                             temp == (unsigned int)((hdrlen - 8) / 16))
 193                                 return ret;
 194                         else
 195                                 return false;
 196                 }
 197         }
 198
 199         return false;
 200 }
 201
 202 /* Called when user tries to insert an entry of this type. */
 203 static bool
 204 checkentry(const char *tablename,
 205            const void *entry,
 206            const struct xt_match *match,
 207            void *matchinfo,
 208            unsigned int hook_mask)
 209 {
 210         const struct ip6t_rt *rtinfo = matchinfo;
 211
 212         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 213                 DEBUGP("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 214                 return false;
 215         }
 216         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 217             (!(rtinfo->flags & IP6T_RT_TYP) ||
 218              (rtinfo->rt_type != 0) ||
 219              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 220                 DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 221                 return false;
 222         }
 223
 224         return true;
 225 }
 226
 227 static struct xt_match rt_match = {
 228         .name           = "rt",
 229         .family         = AF_INET6,
 230         .match          = match,
 231         .matchsize      = sizeof(struct ip6t_rt),
 232         .checkentry     = checkentry,
 233         .me             = THIS_MODULE,
 234 };
 235
 236 static int __init ip6t_rt_init(void)
 237 {
 238         return xt_register_match(&rt_match);
 239 }
 240
 241 static void __exit ip6t_rt_fini(void)
 242 {
 243         xt_unregister_match(&rt_match);
 244 }
 245
 246 module_init(ip6t_rt_init);
 247 module_exit(ip6t_rt_fini);