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 void *matchinfo,
  49       int offset,
  50       unsigned int protoff,
  51       int *hotdrop)
  52 {
  53         struct ipv6_rt_hdr _route, *rh;
  54         const struct ip6t_rt *rtinfo = matchinfo;
  55         unsigned int temp;
  56         unsigned int ptr;
  57         unsigned int hdrlen = 0;
  58         unsigned int ret = 0;
  59         struct in6_addr *ap, _addr;
  60
  61         if (ipv6_find_hdr(skb, &ptr, NEXTHDR_ROUTING, NULL) < 0)
  62                 return 0;
  63
  64         rh = skb_header_pointer(skb, ptr, sizeof(_route), &_route);
  65         if (rh == NULL) {
  66                 *hotdrop = 1;
  67                 return 0;
  68         }
  69
  70         hdrlen = ipv6_optlen(rh);
  71         if (skb->len - ptr < hdrlen) {
  72                 /* Pcket smaller than its length field */
  73                 return 0;
  74         }
  75
  76         DEBUGP("IPv6 RT LEN %u %u ", hdrlen, rh->hdrlen);
  77         DEBUGP("TYPE %04X ", rh->type);
  78         DEBUGP("SGS_LEFT %u %02X\n", rh->segments_left, rh->segments_left);
  79
  80         DEBUGP("IPv6 RT segsleft %02X ",
  81                (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
  82                                rh->segments_left,
  83                                !!(rtinfo->invflags & IP6T_RT_INV_SGS))));
  84         DEBUGP("type %02X %02X %02X ",
  85                rtinfo->rt_type, rh->type,
  86                (!(rtinfo->flags & IP6T_RT_TYP) ||
  87                 ((rtinfo->rt_type == rh->type) ^
  88                  !!(rtinfo->invflags & IP6T_RT_INV_TYP))));
  89         DEBUGP("len %02X %04X %02X ",
  90                rtinfo->hdrlen, hdrlen,
  91                (!(rtinfo->flags & IP6T_RT_LEN) ||
  92                 ((rtinfo->hdrlen == hdrlen) ^
  93                  !!(rtinfo->invflags & IP6T_RT_INV_LEN))));
  94         DEBUGP("res %02X %02X %02X ",
  95                (rtinfo->flags & IP6T_RT_RES),
  96                ((struct rt0_hdr *)rh)->reserved,
  97                !((rtinfo->flags & IP6T_RT_RES) &&
  98                  (((struct rt0_hdr *)rh)->reserved)));
  99
 100         ret = (rh != NULL)
 101               &&
 102               (segsleft_match(rtinfo->segsleft[0], rtinfo->segsleft[1],
 103                               rh->segments_left,
 104                               !!(rtinfo->invflags & IP6T_RT_INV_SGS)))
 105               &&
 106               (!(rtinfo->flags & IP6T_RT_LEN) ||
 107                ((rtinfo->hdrlen == hdrlen) ^
 108                 !!(rtinfo->invflags & IP6T_RT_INV_LEN)))
 109               &&
 110               (!(rtinfo->flags & IP6T_RT_TYP) ||
 111                ((rtinfo->rt_type == rh->type) ^
 112                 !!(rtinfo->invflags & IP6T_RT_INV_TYP)));
 113
 114         if (ret && (rtinfo->flags & IP6T_RT_RES)) {
 115                 u_int32_t *rp, _reserved;
 116                 rp = skb_header_pointer(skb,
 117                                         ptr + offsetof(struct rt0_hdr,
 118                                                        reserved),
 119                                         sizeof(_reserved),
 120                                         &_reserved);
 121
 122                 ret = (*rp == 0);
 123         }
 124
 125         DEBUGP("#%d ", rtinfo->addrnr);
 126         if (!(rtinfo->flags & IP6T_RT_FST)) {
 127                 return ret;
 128         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 129                 DEBUGP("Not strict ");
 130                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 131                         DEBUGP("There isn't enough space\n");
 132                         return 0;
 133                 } else {
 134                         unsigned int i = 0;
 135
 136                         DEBUGP("#%d ", rtinfo->addrnr);
 137                         for (temp = 0;
 138                              temp < (unsigned int)((hdrlen - 8) / 16);
 139                              temp++) {
 140                                 ap = skb_header_pointer(skb,
 141                                                         ptr
 142                                                         + sizeof(struct rt0_hdr)
 143                                                         + temp * sizeof(_addr),
 144                                                         sizeof(_addr),
 145                                                         &_addr);
 146
 147                                 BUG_ON(ap == NULL);
 148
 149                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 150                                         DEBUGP("i=%d temp=%d;\n", i, temp);
 151                                         i++;
 152                                 }
 153                                 if (i == rtinfo->addrnr)
 154                                         break;
 155                         }
 156                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 157                         if (i == rtinfo->addrnr)
 158                                 return ret;
 159                         else
 160                                 return 0;
 161                 }
 162         } else {
 163                 DEBUGP("Strict ");
 164                 if (rtinfo->addrnr > (unsigned int)((hdrlen - 8) / 16)) {
 165                         DEBUGP("There isn't enough space\n");
 166                         return 0;
 167                 } else {
 168                         DEBUGP("#%d ", rtinfo->addrnr);
 169                         for (temp = 0; temp < rtinfo->addrnr; temp++) {
 170                                 ap = skb_header_pointer(skb,
 171                                                         ptr
 172                                                         + sizeof(struct rt0_hdr)
 173                                                         + temp * sizeof(_addr),
 174                                                         sizeof(_addr),
 175                                                         &_addr);
 176                                 BUG_ON(ap == NULL);
 177
 178                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 179                                         break;
 180                         }
 181                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 182                         if ((temp == rtinfo->addrnr) &&
 183                             (temp == (unsigned int)((hdrlen - 8) / 16)))
 184                                 return ret;
 185                         else
 186                                 return 0;
 187                 }
 188         }
 189
 190         return 0;
 191 }
 192
 193 /* Called when user tries to insert an entry of this type. */
 194 static int
 195 checkentry(const char *tablename,
 196            const void *entry,
 197            void *matchinfo,
 198            unsigned int matchinfosize,
 199            unsigned int hook_mask)
 200 {
 201         const struct ip6t_rt *rtinfo = matchinfo;
 202
 203         if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_rt))) {
 204                 DEBUGP("ip6t_rt: matchsize %u != %u\n",
 205                        matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_rt)));
 206                 return 0;
 207         }
 208         if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 209                 DEBUGP("ip6t_rt: unknown flags %X\n", rtinfo->invflags);
 210                 return 0;
 211         }
 212         if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) &&
 213             (!(rtinfo->flags & IP6T_RT_TYP) ||
 214              (rtinfo->rt_type != 0) ||
 215              (rtinfo->invflags & IP6T_RT_INV_TYP))) {
 216                 DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 217                 return 0;
 218         }
 219
 220         return 1;
 221 }
 222
 223 static struct ip6t_match rt_match = {
 224         .name           = "rt",
 225         .match          = &match,
 226         .checkentry     = &checkentry,
 227         .me             = THIS_MODULE,
 228 };
 229
 230 static int __init init(void)
 231 {
 232         return ip6t_register_match(&rt_match);
 233 }
 234
 235 static void __exit cleanup(void)
 236 {
 237         ip6t_unregister_match(&rt_match);
 238 }
 239
 240 module_init(init);
 241 module_exit(cleanup);