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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 rt_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
  40 {
  41         struct ipv6_rt_hdr _route;
  42         const struct ipv6_rt_hdr *rh;
  43         const struct ip6t_rt *rtinfo = par->matchinfo;
  44         unsigned int temp;
  45         unsigned int ptr;
  46         unsigned int hdrlen = 0;
  47         bool ret = false;
  48         struct in6_addr _addr;
  49         const struct in6_addr *ap;
  50         int err;
  51
  52         err = ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL);
  53         if (err < 0) {
  54                 if (err != -ENOENT)
  55                         *par->hotdrop = true;
  56                 return false;
  57         }
  58
  59         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  60         if (rh == NULL) {
  61                 *par->hotdrop = true;
  62                 return false;
  63         }
  64
  65         hdrlen = ipv6_optlen(rh);
  66         if (skb->len - ptr < hdrlen) {
  67                 /* Pcket smaller than its length field */
  68                 return false;
  69         }
  70
  71         pr_debug("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  72         pr_debug("TYPE %04X ", rh->type);
  73         pr_debug("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  74
  75         pr_debug("IPv6 RT segsleft %02X ",
  76                  segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  77                                 rh->segments_left,
  78                                 !!(rtinfo->invflags & IP6T_RT_INV_SGS)));
  79         pr_debug("type %02X %02X %02X ",
  80                  rtinfo->rt_type, rh->type,
  81                  (!(rtinfo->flags & IP6T_RT_TYP) ||
  82                   ((rtinfo->rt_type == rh->type) ^
  83                    !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  84         pr_debug("len %02X %04X %02X ",
  85                  rtinfo->hdrlen, hdrlen,
  86                  !(rtinfo->flags & IP6T_RT_LEN) ||
  87                   ((rtinfo->hdrlen == hdrlen) ^
  88                    !!(rtinfo->invflags & IP6T_RT_INV_LEN)));
  89         pr_debug("res %02X %02X %02X ",
  90                  rtinfo->flags & IP6T_RT_RES,
  91                  ((const struct rt0_hdr *)rh)->reserved,
  92                  !((rtinfo->flags & IP6T_RT_RES) &&
  93                    (((const struct rt0_hdr *)rh)->reserved)));
  94
  95         ret = (rh != NULL)
  96               &&
  97               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  98                               rh->segments_left,
  99                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 100               &&
 101               (!(rtinfo->flags & IP6T_RT_LEN) ||
 102                ((rtinfo->hdrlen == hdrlen) ^
 103                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 104               &&
 105               (!(rtinfo->flags & IP6T_RT_TYP) ||
 106                ((rtinfo->rt_type == rh->type) ^
 107                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 108
 109         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 110                 const u_int32_t *rp;
 111                 u_int32_t _reserved;
 112                 rp = skb_header_pointer(skb,
 113                                         ptr + offsetof(struct rt0_hdr,
 114                                                        reserved),
 115                                         sizeof(_reserved),
 116                                         &_reserved);
 117
 118                 ret = (*rp == 0);
 119         }
 120
 121         pr_debug("#%d ", rtinfo->addrnr);
 122         if (!(rtinfo->flags & IP6T_RT_FST)) {
 123                 return ret;
 124         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 125                 pr_debug("Not strict ");
 126                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 127                         pr_debug("There isn't enough space\n");
 128                         return false;
 129                 } else {
 130                         unsigned int i = 0;
 131
 132                         pr_debug("#%d ", rtinfo->addrnr);
 133                         for (temp = 0;
 134                              temp < (unsigned int)((hdrlen - 8) / 16);
 135                              temp++) {
 136                                 ap = skb_header_pointer(skb,
 137                                                         ptr
 138                                                         + sizeof(struct rt0_hdr)
 139                                                         + temp * sizeof(_addr),
 140                                                         sizeof(_addr),
 141                                                         &_addr);
 142
 143                                 BUG_ON(ap == NULL);
 144
 145                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 146                                         pr_debug("i=%d temp=%d;\n", i, temp);
 147                                         i++;
 148                                 }
 149                                 if (i == rtinfo->addrnr)
 150                                         break;
 151                         }
 152                         pr_debug("i=%d #%d\n", i, rtinfo->addrnr);
 153                         if (i == rtinfo->addrnr)
 154                                 return ret;
 155                         else
 156                                 return false;
 157                 }
 158         } else {
 159                 pr_debug("Strict ");
 160                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 161                         pr_debug("There isn't enough space\n");
 162                         return false;
 163                 } else {
 164                         pr_debug("#%d ", rtinfo->addrnr);
 165                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 166                                 ap = skb_header_pointer(skb,
 167                                                         ptr
 168                                                         + sizeof(struct rt0_hdr)
 169                                                         + temp * sizeof(_addr),
 170                                                         sizeof(_addr),
 171                                                         &_addr);
 172                                 BUG_ON(ap == NULL);
 173
 174                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 175                                         break;
 176                         }
 177                         pr_debug("temp=%d #%d\n", temp, rtinfo->addrnr);
 178                         if (temp == rtinfo->addrnr &&
 179                             temp == (unsigned int)((hdrlen - 8) / 16))
 180                                 return ret;
 181                         else
 182                                 return false;
 183                 }
 184         }
 185
 186         return false;
 187 }
 188
 189 static bool rt_mt6_check(const struct xt_mtchk_param *par)
 190 {
 191         const struct ip6t_rt *rtinfo = par->matchinfo;
 192
 193         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 194                 pr_debug("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 195                 return false;
 196         }
 197         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 198             (!(rtinfo->flags & IP6T_RT_TYP) ||
 199              (rtinfo->rt_type != 0) ||
 200              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 201                 pr_debug("`--rt-type 0' required before `--rt-0-*'");
 202                 return false;
 203         }
 204
 205         return true;
 206 }
 207
 208 static struct xt_match rt_mt6_reg __read_mostly = {
 209         .name           = "rt",
 210         .family         = NFPROTO_IPV6,
 211         .match          = rt_mt6,
 212         .matchsize      = sizeof(struct ip6t_rt),
 213         .checkentry     = rt_mt6_check,
 214         .me             = THIS_MODULE,
 215 };
 216
 217 static int __init rt_mt6_init(void)
 218 {
 219         return xt_register_match(&rt_mt6_reg);
 220 }
 221
 222 static void __exit rt_mt6_exit(void)
 223 {
 224         xt_unregister_match(&rt_mt6_reg);
 225 }
 226
 227 module_init(rt_mt6_init);
 228 module_exit(rt_mt6_exit);