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",invert? '!':' ',
  38               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), ((struct rt0_hdr *)rh)->reserved,
  96                 !((rtinfo->flags & IP6T_RT_RES) && (((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                 u_int32_t *rp, _reserved;
 114                 rp = skb_header_pointer(skb,
 115                                         ptr + offsetof(struct rt0_hdr, reserved),
 116                                         sizeof(_reserved), &_reserved);
 117
 118                 ret = (*rp == 0);
 119         }
 120
 121         DEBUGP("#%d ",rtinfo->addrnr);
 122        if ( !(rtinfo->flags & IP6T_RT_FST) ){
 123                return ret;
 124         } else if (rtinfo->flags & IP6T_RT_FST_NSTRICT) {
 125                 DEBUGP("Not strict ");
 126                 if ( rtinfo->addrnr > (unsigned int)((hdrlen-8)/16) ){
 127                         DEBUGP("There isn't enough space\n");
 128                         return 0;
 129                 } else {
 130                         unsigned int i = 0;
 131
 132                         DEBUGP("#%d ",rtinfo->addrnr);
 133                         for(temp=0; temp<(unsigned int)((hdrlen-8)/16); temp++){
 134                                 ap = skb_header_pointer(skb,
 135                                                         ptr
 136                                                         + sizeof(struct rt0_hdr)
 137                                                         + temp * sizeof(_addr),
 138                                                         sizeof(_addr),
 139                                                         &_addr);
 140
 141                                 BUG_ON(ap == NULL);
 142
 143                                 if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
 144                                         DEBUGP("i=%d temp=%d;\n",i,temp);
 145                                         i++;
 146                                 }
 147                                 if (i==rtinfo->addrnr) break;
 148                         }
 149                         DEBUGP("i=%d #%d\n", i, rtinfo->addrnr);
 150                         if (i == rtinfo->addrnr)
 151                                 return ret;
 152                         else return 0;
 153                 }
 154         } else {
 155                 DEBUGP("Strict ");
 156                 if ( rtinfo->addrnr > (unsigned int)((hdrlen-8)/16) ){
 157                         DEBUGP("There isn't enough space\n");
 158                         return 0;
 159                 } else {
 160                         DEBUGP("#%d ",rtinfo->addrnr);
 161                         for(temp=0; temp<rtinfo->addrnr; temp++){
 162                                 ap = skb_header_pointer(skb,
 163                                                         ptr
 164                                                         + sizeof(struct rt0_hdr)
 165                                                         + temp * sizeof(_addr),
 166                                                         sizeof(_addr),
 167                                                         &_addr);
 168                                 BUG_ON(ap == NULL);
 169
 170                                 if (!ipv6_addr_equal(ap, &rtinfo->addrs[temp]))
 171                                         break;
 172                         }
 173                         DEBUGP("temp=%d #%d\n", temp, rtinfo->addrnr);
 174                         if ((temp == rtinfo->addrnr) && (temp == (unsigned int)((hdrlen-8)/16)))
 175                                 return ret;
 176                         else return 0;
 177                 }
 178         }
 179
 180         return 0;
 181 }
 182
 183 /* Called when user tries to insert an entry of this type. */
 184 static int
 185 checkentry(const char *tablename,
 186           const void *entry,
 187           void *matchinfo,
 188           unsigned int matchinfosize,
 189           unsigned int hook_mask)
 190 {
 191        const struct ip6t_rt *rtinfo = matchinfo;
 192
 193        if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_rt))) {
 194               DEBUGP("ip6t_rt: matchsize %u != %u\n",
 195                       matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_rt)));
 196               return 0;
 197        }
 198        if (rtinfo->invflags & ~IP6T_RT_INV_MASK) {
 199               DEBUGP("ip6t_rt: unknown flags %X\n",
 200                       rtinfo->invflags);
 201               return 0;
 202        }
 203        if ( (rtinfo->flags & (IP6T_RT_RES|IP6T_RT_FST_MASK)) &&
 204                        (!(rtinfo->flags & IP6T_RT_TYP) ||
 205                        (rtinfo->rt_type != 0) ||
 206                        (rtinfo->invflags & IP6T_RT_INV_TYP)) ) {
 207               DEBUGP("`--rt-type 0' required before `--rt-0-*'");
 208               return 0;
 209        }
 210
 211        return 1;
 212 }
 213
 214 static struct ip6t_match rt_match = {
 215         .name           = "rt",
 216         .match          = &match,
 217         .checkentry     = &checkentry,
 218         .me             = THIS_MODULE,
 219 };
 220
 221 static int __init init(void)
 222 {
 223        return ip6t_register_match(&rt_match);
 224 }
 225
 226 static void __exit cleanup(void)
 227 {
 228        ip6t_unregister_match(&rt_match);
 229 }
 230
 231 module_init(init);
 232 module_exit(cleanup);