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   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("Xtables: IPv6 Routing Header match");
  25 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
  26
  27 /* Returns 1 if the id is matched by the range, 0 otherwise */
  28 static inline bool
  29 segsleft_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
  30 {
  31         bool r;
  32         pr_debug("rt segsleft_match:%c 0x%x <= 0x%x <= 0x%x",
  33                  invert ? '!' : ' ', min, id, max);
  34         r = (id >= min && id <= max) ^ invert;
  35         pr_debug(" result %s\n", r ? "PASS" : "FAILED");
  36         return r;
  37 }
  38
  39 static bool
  40 rt_mt6(const struct sk_buff *skb, const struct net_device *in,
  41        const struct net_device *out, const struct xt_match *match,
  42        const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop)
  43 {
  44         struct ipv6_rt_hdr _route;
  45         const struct ipv6_rt_hdr *rh;
  46         const struct ip6t_rt *rtinfo = matchinfo;
  47         unsigned int temp;
  48         unsigned int ptr;
  49         unsigned int hdrlen = 0;
  50         bool ret = false;
  51         struct in6_addr _addr;
  52         const struct in6_addr *ap;
  53         int err;
  54
  55         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
  56         if (err < 0) {
  57                 if (err != -ENOENT)
  58                         *hotdrop = true;
  59                 return false;
  60         }
  61
  62         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  63         if (rh == NULL) {
  64                 *hotdrop = true;
  65                 return false;
  66         }
  67
  68         hdrlen = ipv6_optlen(rh);
  69         if (skb->len - ptr < hdrlen) {
  70                 /* Pcket smaller than its length field */
  71                 return false;
  72         }
  73
  74         pr_debug("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  75         pr_debug("TYPE %04X ", rh->type);
  76         pr_debug("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  77
  78         pr_debug("IPv6 RT segsleft %02X ",
  79                  segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  80                                 rh->segments_left,
  81                                 !!(rtinfo->invflags & IP6T_RT_INV_SGS)));
  82         pr_debug("type %02X %02X %02X ",
  83                  rtinfo->rt_type, rh->type,
  84                  (!(rtinfo->flags & IP6T_RT_TYP) ||
  85                   ((rtinfo->rt_type == rh->type) ^
  86                    !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  87         pr_debug("len %02X %04X %02X ",
  88                  rtinfo->hdrlen, hdrlen,
  89                  !(rtinfo->flags & IP6T_RT_LEN) ||
  90                   ((rtinfo->hdrlen == hdrlen) ^
  91                    !!(rtinfo->invflags & IP6T_RT_INV_LEN)));
  92         pr_debug("res %02X %02X %02X ",
  93                  rtinfo->flags & IP6T_RT_RES,
  94                  ((const struct rt0_hdr *)rh)->reserved,
  95                  !((rtinfo->flags & IP6T_RT_RES) &&
  96                    (((const struct rt0_hdr *)rh)->reserved)));
  97
  98         ret = (rh != NULL)
  99               &&
 100               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 101                               rh->segments_left,
 102                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 103               &&
 104               (!(rtinfo->flags & IP6T_RT_LEN) ||
 105                ((rtinfo->hdrlen == hdrlen) ^
 106                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 107               &&
 108               (!(rtinfo->flags & IP6T_RT_TYP) ||
 109                ((rtinfo->rt_type == rh->type) ^
 110                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 111
 112         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 113                 const u_int32_t *rp;
 114                 u_int32_t _reserved;
 115                 rp = skb_header_pointer(skb,
 116                                         ptr + offsetof(struct rt0_hdr,
 117                                                        reserved),
 118                                         sizeof(_reserved),
 119                                         &_reserved);
 120
 121                 ret = (*rp == 0);
 122         }
 123
 124         pr_debug("#%d ", rtinfo->addrnr);
 125         if (!(rtinfo->flags & IP6T_RT_FST)) {
 126                 return ret;
 127         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 128                 pr_debug("Not strict ");
 129                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 130                         pr_debug("There isn't enough space\n");
 131                         return false;
 132                 } else {
 133                         unsigned int i = 0;
 134
 135                         pr_debug("#%d ", rtinfo->addrnr);
 136                         for (temp = 0;
 137                              temp < (unsigned int)((hdrlen - 8) / 16);
 138                              temp++) {
 139                                 ap = skb_header_pointer(skb,
 140                                                         ptr
 141                                                         + sizeof(struct rt0_hdr)
 142                                                         + temp * sizeof(_addr),
 143                                                         sizeof(_addr),
 144                                                         &_addr);
 145
 146                                 BUG_ON(ap == NULL);
 147
 148                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 149                                         pr_debug("i=%d temp=%d;\n", i, temp);
 150                                         i++;
 151                                 }
 152                                 if (i == rtinfo->addrnr)
 153                                         break;
 154                         }
 155                         pr_debug("i=%d #%d\n", i, rtinfo->addrnr);
 156                         if (i == rtinfo->addrnr)
 157                                 return ret;
 158                         else
 159                                 return false;
 160                 }
 161         } else {
 162                 pr_debug("Strict ");
 163                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 164                         pr_debug("There isn't enough space\n");
 165                         return false;
 166                 } else {
 167                         pr_debug("#%d ", rtinfo->addrnr);
 168                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 169                                 ap = skb_header_pointer(skb,
 170                                                         ptr
 171                                                         + sizeof(struct rt0_hdr)
 172                                                         + temp * sizeof(_addr),
 173                                                         sizeof(_addr),
 174                                                         &_addr);
 175                                 BUG_ON(ap == NULL);
 176
 177                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 178                                         break;
 179                         }
 180                         pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr);
 181                         if (temp == rtinfo->addrnr &&
 182                             temp == (unsigned int)((hdrlen - 8) / 16))
 183                                 return ret;
 184                         else
 185                                 return false;
 186                 }
 187         }
 188
 189         return false;
 190 }
 191
 192 /* Called when user tries to insert an entry of this type. */
 193 static bool
 194 rt_mt6_check(const char *tablename, const void *entry,
 195              const struct xt_match *match, void *matchinfo,
 196              unsigned int hook_mask)
 197 {
 198         const struct ip6t_rt *rtinfo = matchinfo;
 199
 200         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 201                 pr_debug("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 202                 return false;
 203         }
 204         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 205             (!(rtinfo->flags & IP6T_RT_TYP) ||
 206              (rtinfo->rt_type != 0) ||
 207              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 208                 pr_debug("`--rt-type 0' required before `--rt-0-*'");
 209                 return false;
 210         }
 211
 212         return true;
 213 }
 214
 215 static struct xt_match rt_mt6_reg __read_mostly = {
 216         .name           = "rt",
 217         .family         = AF_INET6,
 218         .match          = rt_mt6,
 219         .matchsize      = sizeof(struct ip6t_rt),
 220         .checkentry     = rt_mt6_check,
 221         .me             = THIS_MODULE,
 222 };
 223
 224 static int __init rt_mt6_init(void)
 225 {
 226         return xt_register_match(&rt_mt6_reg);
 227 }
 228
 229 static void __exit rt_mt6_exit(void)
 230 {
 231         xt_unregister_match(&rt_mt6_reg);
 232 }
 233
 234 module_init(rt_mt6_init);
 235 module_exit(rt_mt6_exit);