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 (at) 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 } 317
