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 struct xt_match *match,
  49       const void *matchinfo,
  50       int offset,
  51       unsigned int protoff,
  52       int *hotdrop)
  53 {
  54         struct ipv6_rt_hdr _route, *rh;
  55         const struct ip6t_rt *rtinfo = matchinfo;
  56         unsigned int temp;
  57         unsigned int ptr;
  58         unsigned int hdrlen = 0;
  59         unsigned int ret = 0;
  60         struct in6_addr *ap, _addr;
  61         int err;
  62
  63         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
  64         if (err < 0) {
  65                 if (err != -ENOENT)
  66                         *hotdrop = 1;
  67                 return 0;
  68         }
  69
  70         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  71         if (rh == NULL) {
  72                 *hotdrop = 1;
  73                 return 0;
  74         }
  75
  76         hdrlen = ipv6_optlen(rh);
  77         if (skb->len - ptr < hdrlen) {
  78                 /* Pcket smaller than its length field */
  79                 return 0;
  80         }
  81
  82         DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  83         DEBUGP("TYPE %04X ", rh->type);
  84         DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  85
  86         DEBUGP("IPv6 RT segsleft %02X ",
  87                (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  88                                rh->segments_left,
  89                                !!(rtinfo->invflags & IP6T_RT_INV_SGS))));
  90         DEBUGP("type %02X %02X %02X ",
  91                rtinfo->rt_type, rh->type,
  92                (!(rtinfo->flags & IP6T_RT_TYP) ||
  93                 ((rtinfo->rt_type == rh->type) ^
  94                  !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  95         DEBUGP("len %02X %04X %02X ",
  96                rtinfo->hdrlen, hdrlen,
  97                (!(rtinfo->flags & IP6T_RT_LEN) ||
  98                 ((rtinfo->hdrlen == hdrlen) ^
  99                  !!(rtinfo->invflags & IP6T_RT_INV_LEN))));
 100         DEBUGP("res %02X %02X %02X ",
 101                (rtinfo->flags & IP6T_RT_RES),
 102                ((struct rt0_hdr *)rh)->reserved,
 103                !((rtinfo->flags & IP6T_RT_RES) &&
 104                  (((struct rt0_hdr *)rh)->reserved)));
 105
 106         ret = (rh != NULL)
 107               &&
 108               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 109                               rh->segments_left,
 110                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 111               &&
 112               (!(rtinfo->flags & IP6T_RT_LEN) ||
 113                ((rtinfo->hdrlen == hdrlen) ^
 114                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 115               &&
 116               (!(rtinfo->flags & IP6T_RT_TYP) ||
 117                ((rtinfo->rt_type == rh->type) ^
 118                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 119
 120         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 121                 u_int32_t *rp, _reserved;
 122                 rp = skb_header_pointer(skb,
 123                                         ptr + offsetof(struct rt0_hdr,
 124                                                        reserved),
 125                                         sizeof(_reserved),
 126                                         &_reserved);
 127
 128                 ret = (*rp == 0);
 129         }
 130
 131         DEBUGP("#%d ", rtinfo->addrnr);
 132         if (!(rtinfo->flags & IP6T_RT_FST)) {
 133                 return ret;
 134         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 135                 DEBUGP("Not strict ");
 136                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 137                         DEBUGP("There isn't enough space\n");
 138                         return 0;
 139                 } else {
 140                         unsigned int i = 0;
 141
 142                         DEBUGP("#%d ", rtinfo->addrnr);
 143                         for (temp = 0;
 144                              temp < (unsigned int)((hdrlen - 8) / 16);
 145                              temp++) {
 146                                 ap = skb_header_pointer(skb,
 147                                                         ptr
 148                                                         + sizeof(struct rt0_hdr)
 149                                                         + temp * sizeof(_addr),
 150                                                         sizeof(_addr),
 151                                                         &_addr);
 152
 153                                 BUG_ON(ap == NULL);
 154
 155                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 156                                         DEBUGP("i=%d temp=%d;\n", i, temp);
 157                                         i++;
 158                                 }
 159                                 if (i == rtinfo->addrnr)
 160                                         break;
 161                         }
 162                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 163                         if (i == rtinfo->addrnr)
 164                                 return ret;
 165                         else
 166                                 return 0;
 167                 }
 168         } else {
 169                 DEBUGP("Strict ");
 170                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 171                         DEBUGP("There isn't enough space\n");
 172                         return 0;
 173                 } else {
 174                         DEBUGP("#%d ", rtinfo->addrnr);
 175                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 176                                 ap = skb_header_pointer(skb,
 177                                                         ptr
 178                                                         + sizeof(struct rt0_hdr)
 179                                                         + temp * sizeof(_addr),
 180                                                         sizeof(_addr),
 181                                                         &_addr);
 182                                 BUG_ON(ap == NULL);
 183
 184                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 185                                         break;
 186                         }
 187                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 188                         if ((temp == rtinfo->addrnr) &&
 189                             (temp == (unsigned int)((hdrlen - 8) / 16)))
 190                                 return ret;
 191                         else
 192                                 return 0;
 193                 }
 194         }
 195
 196         return 0;
 197 }
 198
 199 /* Called when user tries to insert an entry of this type. */
 200 static int
 201 checkentry(const char *tablename,
 202            const void *entry,
 203            const struct xt_match *match,
 204            void *matchinfo,
 205            unsigned int hook_mask)
 206 {
 207         const struct ip6t_rt *rtinfo = matchinfo;
 208
 209         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 210                 DEBUGP("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 211                 return 0;
 212         }
 213         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 214             (!(rtinfo->flags & IP6T_RT_TYP) ||
 215              (rtinfo->rt_type != 0) ||
 216              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 217                 DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 218                 return 0;
 219         }
 220
 221         return 1;
 222 }
 223
 224 static struct ip6t_match rt_match = {
 225         .name           = "rt",
 226         .match          = match,
 227         .matchsize      = sizeof(struct ip6t_rt),
 228         .checkentry     = checkentry,
 229         .me             = THIS_MODULE,
 230 };
 231
 232 static int __init ip6t_rt_init(void)
 233 {
 234         return ip6t_register_match(&rt_match);
 235 }
 236
 237 static void __exit ip6t_rt_fini(void)
 238 {
 239         ip6t_unregister_match(&rt_match);
 240 }
 241
 242 module_init(ip6t_rt_init);
 243 module_exit(ip6t_rt_fini);