release/src/router/iptables/extensions/libip6t_ipv6header.c

   1 /* ipv6header match - matches IPv6 packets based
   2 on whether they contain certain headers */
   3
   4 /* Original idea: Brad Chapman
   5  * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
   6
   7 #include <getopt.h>
   8 #include <ip6tables.h>
   9 #include <stddef.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <netdb.h>
  14 #include <sys/types.h>
  15
  16 #include <linux/netfilter_ipv6/ip6_tables.h>
  17 #include <linux/netfilter_ipv6/ip6t_ipv6header.h>
  18
  19 /* This maybe required
  20 #include <linux/in.h>
  21 #include <linux/in6.h>
  22 */
  23
  24
  25 /* A few hardcoded protocols for 'all' and in case the user has no
  26  *    /etc/protocols */
  27 struct pprot {
  28         char *name;
  29         u_int8_t num;
  30 };
  31
  32 struct numflag {
  33         u_int8_t proto;
  34         u_int8_t flag;
  35 };
  36
  37 static const struct pprot chain_protos[] = {
  38         { "hop-by-hop", IPPROTO_HOPOPTS },
  39         { "protocol", IPPROTO_RAW },
  40         { "hop", IPPROTO_HOPOPTS },
  41         { "dst", IPPROTO_DSTOPTS },
  42         { "route", IPPROTO_ROUTING },
  43         { "frag", IPPROTO_FRAGMENT },
  44         { "auth", IPPROTO_AH },
  45         { "esp", IPPROTO_ESP },
  46         { "none", IPPROTO_NONE },
  47         { "prot", IPPROTO_RAW },
  48         { "0", IPPROTO_HOPOPTS },
  49         { "60", IPPROTO_DSTOPTS },
  50         { "43", IPPROTO_ROUTING },
  51         { "44", IPPROTO_FRAGMENT },
  52         { "51", IPPROTO_AH },
  53         { "50", IPPROTO_ESP },
  54         { "59", IPPROTO_NONE },
  55         { "255", IPPROTO_RAW },
  56         /* { "all", 0 }, */
  57 };
  58
  59 static const struct numflag chain_flags[] = {
  60         { IPPROTO_HOPOPTS, MASK_HOPOPTS },
  61         { IPPROTO_DSTOPTS, MASK_DSTOPTS },
  62         { IPPROTO_ROUTING, MASK_ROUTING },
  63         { IPPROTO_FRAGMENT, MASK_FRAGMENT },
  64         { IPPROTO_AH, MASK_AH },
  65         { IPPROTO_ESP, MASK_ESP },
  66         { IPPROTO_NONE, MASK_NONE },
  67         { IPPROTO_RAW, MASK_PROTO },
  68 };
  69
  70 static char *
  71 proto_to_name(u_int8_t proto, int nolookup)
  72 {
  73         unsigned int i;
  74
  75         if (proto && !nolookup) {
  76                 struct protoent *pent = getprotobynumber(proto);
  77                 if (pent)
  78                         return pent->p_name;
  79         }
  80
  81         for (i = 0; i < sizeof(chain_protos)/sizeof(struct pprot); i++)
  82                 if (chain_protos[i].num == proto)
  83                         return chain_protos[i].name;
  84
  85         return NULL;
  86 }
  87
  88 static u_int16_t
  89 name_to_proto(const char *s)
  90 {
  91         unsigned int proto=0;
  92         struct protoent *pent;
  93
  94         if ((pent = getprotobyname(s)))
  95                 proto = pent->p_proto;
  96         else {
  97                 unsigned int i;
  98                 for (i = 0;
  99                         i < sizeof(chain_protos)/sizeof(struct pprot);
 100                         i++) {
 101                         if (strcmp(s, chain_protos[i].name) == 0) {
 102                                 proto = chain_protos[i].num;
 103                                 break;
 104                         }
 105                 }
 106
 107                 if (i == sizeof(chain_protos)/sizeof(struct pprot))
 108                         exit_error(PARAMETER_PROBLEM,
 109                                 "unknown header `%s' specified",
 110                                 s);
 111         }
 112
 113         return (u_int16_t)proto;
 114 }
 115
 116 static unsigned int
 117 add_proto_to_mask(int proto){
 118         unsigned int i=0, flag=0;
 119
 120         for (i = 0;
 121                 i < sizeof(chain_flags)/sizeof(struct numflag);
 122                 i++) {
 123                         if (proto == chain_flags[i].proto){
 124                                 flag = chain_flags[i].flag;
 125                                 break;
 126                         }
 127         }
 128
 129         if (i == sizeof(chain_flags)/sizeof(struct numflag))
 130                 exit_error(PARAMETER_PROBLEM,
 131                 "unknown header `%d' specified",
 132                 proto);
 133
 134         return flag;
 135 }
 136
 137 static void
 138 help(void)
 139 {
 140         printf(
 141 "ipv6header v%s match options:\n"
 142 "--header [!] headers     Type of header to match, by name\n"
 143 "                         names: hop,dst,route,frag,auth,esp,none,proto\n"
 144 "                    long names: hop-by-hop,ipv6-opts,ipv6-route,\n"
 145 "                                ipv6-frag,ah,esp,ipv6-nonxt,protocol\n"
 146 "                       numbers: 0,60,43,44,51,50,59\n"
 147 "--soft                    The header CONTAINS the specified extensions\n",
 148         IPTABLES_VERSION);
 149 }
 150
 151 static struct option opts[] = {
 152         { "header", 1, 0, '1' },
 153         { "soft", 0, 0, '2' },
 154         { 0 }
 155 };
 156
 157 static void
 158 init(struct ip6t_entry_match *m, unsigned int *nfcache)
 159 {
 160         struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)m->data;
 161
 162         info->matchflags = 0x00;
 163         info->invflags = 0x00;
 164         info->modeflag = 0x00;
 165 }
 166
 167 static unsigned int
 168 parse_header(const char *flags) {
 169         unsigned int ret = 0;
 170         char *ptr;
 171         char *buffer;
 172
 173         buffer = strdup(flags);
 174
 175         for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ","))
 176                 ret |= add_proto_to_mask(name_to_proto(ptr));
 177
 178         free(buffer);
 179         return ret;
 180 }
 181
 182 #define IPV6_HDR_HEADER 0x01
 183 #define IPV6_HDR_SOFT   0x02
 184
 185 /* Parses command options; returns 0 if it ate an option */
 186 static int
 187 parse(int c, char **argv, int invert, unsigned int *flags,
 188       const struct ip6t_entry *entry,
 189       unsigned int *nfcache,
 190       struct ip6t_entry_match **match)
 191 {
 192         struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)(*match)->data;
 193
 194         switch (c) {
 195                 case '1' :
 196                         /* Parse the provided header names */
 197                         if (*flags & IPV6_HDR_HEADER)
 198                                 exit_error(PARAMETER_PROBLEM,
 199                                         "Only one `--header' allowed");
 200
 201                         check_inverse(optarg, &invert, &optind, 0);
 202
 203                         if (! (info->matchflags = parse_header(argv[optind-1])) )
 204                                 exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: cannot parse header names");
 205
 206                         if (invert)
 207                                 info->invflags |= 0xFF;
 208                         *flags |= IPV6_HDR_HEADER;
 209                         break;
 210                 case '2' :
 211                         /* Soft-mode requested? */
 212                         if (*flags & IPV6_HDR_SOFT)
 213                                 exit_error(PARAMETER_PROBLEM,
 214                                         "Only one `--soft' allowed");
 215
 216                         info->modeflag |= 0xFF;
 217                         *flags |= IPV6_HDR_SOFT;
 218                         break;
 219                 default:
 220                         return 0;
 221         }
 222
 223         return 1;
 224 }
 225
 226 /* Checks the flags variable */
 227 static void
 228 final_check(unsigned int flags)
 229 {
 230         if (!flags) exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: no options specified");
 231 }
 232
 233 static void
 234 print_header(u_int8_t flags){
 235         int have_flag = 0;
 236
 237         while (flags) {
 238                 unsigned int i;
 239
 240                 for (i = 0; (flags & chain_flags[i].flag) == 0; i++);
 241
 242                 if (have_flag)
 243                         printf(",");
 244
 245                 printf("%s", proto_to_name(chain_flags[i].proto,0));
 246                 have_flag = 1;
 247
 248                 flags &= ~chain_flags[i].flag;
 249         }
 250
 251         if (!have_flag)
 252                 printf("NONE");
 253 }
 254
 255 /* Prints out the match */
 256 static void
 257 print(const struct ip6t_ip6 *ip,
 258       const struct ip6t_entry_match *match,
 259       int numeric)
 260 {
 261         const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data;
 262         printf("ipv6header ");
 263
 264         if (info->matchflags || info->invflags) {
 265                 printf("flags:%s", info->invflags ? "!" : "");
 266                 if (numeric)
 267                         printf("0x%02X ", info->matchflags);
 268                 else {
 269                         print_header(info->matchflags);
 270                         printf(" ");
 271                 }
 272         }
 273
 274         if (info->modeflag)
 275                 printf("soft ");
 276
 277         return;
 278 }
 279
 280 /* Saves the match */
 281 static void
 282 save(const struct ip6t_ip6 *ip,
 283      const struct ip6t_entry_match *match)
 284 {
 285
 286         const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data;
 287
 288         printf("--header ");
 289         printf("%s", info->invflags ? "!" : "");
 290         print_header(info->matchflags);
 291         printf(" ");
 292         if (info->modeflag)
 293                 printf("--soft ");
 294
 295         return;
 296 }
 297
 298 static
 299 struct ip6tables_match ipv6header = {
 300         .name           = "ipv6header",
 301         .version        = IPTABLES_VERSION,
 302         .size           = IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)),
 303         .userspacesize  = IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)),
 304         .help           = &help,
 305         .init           = &init,
 306         .parse          = &parse,
 307         .final_check    = &final_check,
 308         .print          = &print,
 309         .save           = &save,
 310         .extra_opts     = opts,
 311 };
 312
 313 void _init(void)
 314 {
 315         register_match6(&ipv6header);
 316 }