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, *rh;
  56         const struct ip6t_rt *rtinfo = matchinfo;
  57         unsigned int temp;
  58         unsigned int ptr;
  59         unsigned int hdrlen = 0;
  60         bool ret = false;
  61         struct in6_addr *ap, _addr;
  62         int err;
  63
  64         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
  65         if (err < 0) {
  66                 if (err != -ENOENT)
  67                         *hotdrop = true;
  68                 return false;
  69         }
  70
  71         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  72         if (rh == NULL) {
  73                 *hotdrop = true;
  74                 return false;
  75         }
  76
  77         hdrlen = ipv6_optlen(rh);
  78         if (skb->len - ptr < hdrlen) {
  79                 /* Pcket smaller than its length field */
  80                 return false;
  81         }
  82
  83         DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  84         DEBUGP("TYPE %04X ", rh->type);
  85         DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  86
  87         DEBUGP("IPv6 RT segsleft %02X ",
  88                (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  89                                rh->segments_left,
  90                                !!(rtinfo->invflags & IP6T_RT_INV_SGS))));
  91         DEBUGP("type %02X %02X %02X ",
  92                rtinfo->rt_type, rh->type,
  93                (!(rtinfo->flags & IP6T_RT_TYP) ||
  94                 ((rtinfo->rt_type == rh->type) ^
  95                  !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  96         DEBUGP("len %02X %04X %02X ",
  97                rtinfo->hdrlen, hdrlen,
  98                (!(rtinfo->flags & IP6T_RT_LEN) ||
  99                 ((rtinfo->hdrlen == hdrlen) ^
 100                  !!(rtinfo->invflags & IP6T_RT_INV_LEN))));
 101         DEBUGP("res %02X %02X %02X ",
 102                (rtinfo->flags & IP6T_RT_RES),
 103                ((struct rt0_hdr *)rh)->reserved,
 104                !((rtinfo->flags & IP6T_RT_RES) &&
 105                  (((struct rt0_hdr *)rh)->reserved)));
 106
 107         ret = (rh != NULL)
 108               &&
 109               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 110                               rh->segments_left,
 111                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 112               &&
 113               (!(rtinfo->flags & IP6T_RT_LEN) ||
 114                ((rtinfo->hdrlen == hdrlen) ^
 115                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 116               &&
 117               (!(rtinfo->flags & IP6T_RT_TYP) ||
 118                ((rtinfo->rt_type == rh->type) ^
 119                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 120
 121         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 122                 u_int32_t *rp, _reserved;
 123                 rp = skb_header_pointer(skb,
 124                                         ptr + offsetof(struct rt0_hdr,
 125                                                        reserved),
 126                                         sizeof(_reserved),
 127                                         &_reserved);
 128
 129                 ret = (*rp == 0);
 130         }
 131
 132         DEBUGP("#%d ", rtinfo->addrnr);
 133         if (!(rtinfo->flags & IP6T_RT_FST)) {
 134                 return ret;
 135         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 136                 DEBUGP("Not strict ");
 137                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 138                         DEBUGP("There isn't enough space\n");
 139                         return false;
 140                 } else {
 141                         unsigned int i = 0;
 142
 143                         DEBUGP("#%d ", rtinfo->addrnr);
 144                         for (temp = 0;
 145                              temp < (unsigned int)((hdrlen - 8) / 16);
 146                              temp++) {
 147                                 ap = skb_header_pointer(skb,
 148                                                         ptr
 149                                                         + sizeof(struct rt0_hdr)
 150                                                         + temp * sizeof(_addr),
 151                                                         sizeof(_addr),
 152                                                         &_addr);
 153
 154                                 BUG_ON(ap == NULL);
 155
 156                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 157                                         DEBUGP("i=%d temp=%d;\n", i, temp);
 158                                         i++;
 159                                 }
 160                                 if (i == rtinfo->addrnr)
 161                                         break;
 162                         }
 163                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 164                         if (i == rtinfo->addrnr)
 165                                 return ret;
 166                         else
 167                                 return false;
 168                 }
 169         } else {
 170                 DEBUGP("Strict ");
 171                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 172                         DEBUGP("There isn't enough space\n");
 173                         return false;
 174                 } else {
 175                         DEBUGP("#%d ", rtinfo->addrnr);
 176                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 177                                 ap = skb_header_pointer(skb,
 178                                                         ptr
 179                                                         + sizeof(struct rt0_hdr)
 180                                                         + temp * sizeof(_addr),
 181                                                         sizeof(_addr),
 182                                                         &_addr);
 183                                 BUG_ON(ap == NULL);
 184
 185                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 186                                         break;
 187                         }
 188                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 189                         if ((temp == rtinfo->addrnr) &&
 190                             (temp == (unsigned int)((hdrlen - 8) / 16)))
 191                                 return ret;
 192                         else
 193                                 return false;
 194                 }
 195         }
 196
 197         return false;
 198 }
 199
 200 /* Called when user tries to insert an entry of this type. */
 201 static bool
 202 checkentry(const char *tablename,
 203            const void *entry,
 204            const struct xt_match *match,
 205            void *matchinfo,
 206            unsigned int hook_mask)
 207 {
 208         const struct ip6t_rt *rtinfo = matchinfo;
 209
 210         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 211                 DEBUGP("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 212                 return false;
 213         }
 214         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 215             (!(rtinfo->flags & IP6T_RT_TYP) ||
 216              (rtinfo->rt_type != 0) ||
 217              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 218                 DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 219                 return false;
 220         }
 221
 222         return true;
 223 }
 224
 225 static struct xt_match rt_match = {
 226         .name           = "rt",
 227         .family         = AF_INET6,
 228         .match          = match,
 229         .matchsize      = sizeof(struct ip6t_rt),
 230         .checkentry     = checkentry,
 231         .me             = THIS_MODULE,
 232 };
 233
 234 static int __init ip6t_rt_init(void)
 235 {
 236         return xt_register_match(&rt_match);
 237 }
 238
 239 static void __exit ip6t_rt_fini(void)
 240 {
 241         xt_unregister_match(&rt_match);
 242 }
 243
 244 module_init(ip6t_rt_init);
 245 module_exit(ip6t_rt_fini);