libip6t_ipv6header.c revision 500f483fff529dcd88ec96b9d5054be6cd6363a0
1/* ipv6header match - matches IPv6 packets based 2on 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 */ 27struct pprot { 28 char *name; 29 u_int8_t num; 30}; 31 32struct numflag { 33 u_int8_t proto; 34 u_int8_t flag; 35}; 36 37static 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 59static 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 70static char * 71proto_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 88static u_int16_t 89name_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 116static unsigned int 117add_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 137static void 138help(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 151static const struct option opts[] = { 152 { "header", 1, NULL, '1' }, 153 { "soft", 0, NULL, '2' }, 154 { } 155}; 156 157static void 158init(struct xt_entry_match *m) 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 167static unsigned int 168parse_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 */ 186static int 187parse(int c, char **argv, int invert, unsigned int *flags, 188 const void *entry, 189 struct xt_entry_match **match) 190{ 191 struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)(*match)->data; 192 193 switch (c) { 194 case '1' : 195 /* Parse the provided header names */ 196 if (*flags & IPV6_HDR_HEADER) 197 exit_error(PARAMETER_PROBLEM, 198 "Only one `--header' allowed"); 199 200 check_inverse(optarg, &invert, &optind, 0); 201 202 if (! (info->matchflags = parse_header(argv[optind-1])) ) 203 exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: cannot parse header names"); 204 205 if (invert) 206 info->invflags |= 0xFF; 207 *flags |= IPV6_HDR_HEADER; 208 break; 209 case '2' : 210 /* Soft-mode requested? */ 211 if (*flags & IPV6_HDR_SOFT) 212 exit_error(PARAMETER_PROBLEM, 213 "Only one `--soft' allowed"); 214 215 info->modeflag |= 0xFF; 216 *flags |= IPV6_HDR_SOFT; 217 break; 218 default: 219 return 0; 220 } 221 222 return 1; 223} 224 225/* Checks the flags variable */ 226static void 227final_check(unsigned int flags) 228{ 229 if (!flags) exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: no options specified"); 230} 231 232static void 233print_header(u_int8_t flags){ 234 int have_flag = 0; 235 236 while (flags) { 237 unsigned int i; 238 239 for (i = 0; (flags & chain_flags[i].flag) == 0; i++); 240 241 if (have_flag) 242 printf(","); 243 244 printf("%s", proto_to_name(chain_flags[i].proto,0)); 245 have_flag = 1; 246 247 flags &= ~chain_flags[i].flag; 248 } 249 250 if (!have_flag) 251 printf("NONE"); 252} 253 254/* Prints out the match */ 255static void 256print(const void *ip, 257 const struct xt_entry_match *match, 258 int numeric) 259{ 260 const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data; 261 printf("ipv6header "); 262 263 if (info->matchflags || info->invflags) { 264 printf("flags:%s", info->invflags ? "!" : ""); 265 if (numeric) 266 printf("0x%02X ", info->matchflags); 267 else { 268 print_header(info->matchflags); 269 printf(" "); 270 } 271 } 272 273 if (info->modeflag) 274 printf("soft "); 275 276 return; 277} 278 279/* Saves the match */ 280static void 281save(const void *ip, 282 const struct xt_entry_match *match) 283{ 284 285 const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data; 286 287 printf("--header "); 288 printf("%s", info->invflags ? "!" : ""); 289 print_header(info->matchflags); 290 printf(" "); 291 if (info->modeflag) 292 printf("--soft "); 293 294 return; 295} 296 297static 298struct ip6tables_match ipv6header = { 299 .name = "ipv6header", 300 .version = IPTABLES_VERSION, 301 .size = IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)), 302 .userspacesize = IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)), 303 .help = &help, 304 .init = &init, 305 .parse = &parse, 306 .final_check = &final_check, 307 .print = &print, 308 .save = &save, 309 .extra_opts = opts, 310}; 311 312void _init(void) 313{ 314 register_match6(&ipv6header); 315} 316