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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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("segsleft_match:%c 0x%x <= 0x%x <= 0x%x\n",
  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, struct xt_action_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 = 0;
  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, 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               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  97                               rh->segments_left,
  98                               !!(rtinfo->invflags & IP6T_RT_INV_SGS))) &&
  99               (!(rtinfo->flags & IP6T_RT_LEN) ||
 100                ((rtinfo->hdrlen == hdrlen) ^
 101                 !!(rtinfo->invflags & IP6T_RT_INV_LEN))) &&
 102               (!(rtinfo->flags & IP6T_RT_TYP) ||
 103                ((rtinfo->rt_type == rh->type) ^
 104                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 105
 106         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 107                 const u_int32_t *rp;
 108                 u_int32_t _reserved;
 109                 rp = skb_header_pointer(skb,
 110                                         ptr + offsetof(struct rt0_hdr,
 111                                                        reserved),
 112                                         sizeof(_reserved),
 113                                         &_reserved);
 114
 115                 ret = (*rp == 0);
 116         }
 117
 118         pr_debug("#%d ", rtinfo->addrnr);
 119         if (!(rtinfo->flags & IP6T_RT_FST)) {
 120                 return ret;
 121         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 122                 pr_debug("Not strict ");
 123                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 124                         pr_debug("There isn't enough space\n");
 125                         return false;
 126                 } else {
 127                         unsigned int i = 0;
 128
 129                         pr_debug("#%d ", rtinfo->addrnr);
 130                         for (temp = 0;
 131                              temp < (unsigned int)((hdrlen - 8) / 16);
 132                              temp++) {
 133                                 ap = skb_header_pointer(skb,
 134                                                         ptr
 135                                                         + sizeof(struct rt0_hdr)
 136                                                         + temp * sizeof(_addr),
 137                                                         sizeof(_addr),
 138                                                         &_addr);
 139
 140                                 if (ap == NULL) {
 141                                         par->hotdrop = true;
 142                                         return false;
 143                                 }
 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                                 if (ap == NULL) {
 173                                         par->hotdrop = true;
 174                                         return false;
 175                                 }
 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 static int rt_mt6_check(const struct xt_mtchk_param *par)
 193 {
 194         const struct ip6t_rt *rtinfo = par->matchinfo;
 195
 196         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 197                 pr_debug("unknown flags %X\n", rtinfo->invflags);
 198                 return -EINVAL;
 199         }
 200         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 201             (!(rtinfo->flags & IP6T_RT_TYP) ||
 202              (rtinfo->rt_type != 0) ||
 203              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 204                 pr_debug("`--rt-type 0' required before `--rt-0-*'");
 205                 return -EINVAL;
 206         }
 207
 208         return 0;
 209 }
 210
 211 static struct xt_match rt_mt6_reg __read_mostly = {
 212         .name           = "rt",
 213         .family         = NFPROTO_IPV6,
 214         .match          = rt_mt6,
 215         .matchsize      = sizeof(struct ip6t_rt),
 216         .checkentry     = rt_mt6_check,
 217         .me             = THIS_MODULE,
 218 };
 219
 220 static int __init rt_mt6_init(void)
 221 {
 222         return xt_register_match(&rt_mt6_reg);
 223 }
 224
 225 static void __exit rt_mt6_exit(void)
 226 {
 227         xt_unregister_match(&rt_mt6_reg);
 228 }
 229
 230 module_init(rt_mt6_init);
 231 module_exit(rt_mt6_exit);