libip6t_ipv6header.c revision 967279231a9ecfa99f26694a954afc535c63db1d
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 ipv6header_help(void) 138{ 139 printf( 140"ipv6header match options:\n" 141"[!] --header headers Type of header to match, by name\n" 142" names: hop,dst,route,frag,auth,esp,none,proto\n" 143" long names: hop-by-hop,ipv6-opts,ipv6-route,\n" 144" ipv6-frag,ah,esp,ipv6-nonxt,protocol\n" 145" numbers: 0,60,43,44,51,50,59\n" 146"--soft The header CONTAINS the specified extensions\n"); 147} 148 149static const struct option ipv6header_opts[] = { 150 { "header", 1, NULL, '1' }, 151 { "soft", 0, NULL, '2' }, 152 { .name = NULL } 153}; 154 155static void ipv6header_init(struct xt_entry_match *m) 156{ 157 struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)m->data; 158 159 info->matchflags = 0x00; 160 info->invflags = 0x00; 161 info->modeflag = 0x00; 162} 163 164static unsigned int 165parse_header(const char *flags) { 166 unsigned int ret = 0; 167 char *ptr; 168 char *buffer; 169 170 buffer = strdup(flags); 171 172 for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) 173 ret |= add_proto_to_mask(name_to_proto(ptr)); 174 175 free(buffer); 176 return ret; 177} 178 179#define IPV6_HDR_HEADER 0x01 180#define IPV6_HDR_SOFT 0x02 181 182/* Parses command options; returns 0 if it ate an option */ 183static int 184ipv6header_parse(int c, char **argv, int invert, unsigned int *flags, 185 const void *entry, struct xt_entry_match **match) 186{ 187 struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)(*match)->data; 188 189 switch (c) { 190 case '1' : 191 /* Parse the provided header names */ 192 if (*flags & IPV6_HDR_HEADER) 193 exit_error(PARAMETER_PROBLEM, 194 "Only one `--header' allowed"); 195 196 check_inverse(optarg, &invert, &optind, 0); 197 198 if (! (info->matchflags = parse_header(argv[optind-1])) ) 199 exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: cannot parse header names"); 200 201 if (invert) 202 info->invflags |= 0xFF; 203 *flags |= IPV6_HDR_HEADER; 204 break; 205 case '2' : 206 /* Soft-mode requested? */ 207 if (*flags & IPV6_HDR_SOFT) 208 exit_error(PARAMETER_PROBLEM, 209 "Only one `--soft' allowed"); 210 211 info->modeflag |= 0xFF; 212 *flags |= IPV6_HDR_SOFT; 213 break; 214 default: 215 return 0; 216 } 217 218 return 1; 219} 220 221/* Checks the flags variable */ 222static void ipv6header_check(unsigned int flags) 223{ 224 if (!flags) exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: no options specified"); 225} 226 227static void 228print_header(u_int8_t flags){ 229 int have_flag = 0; 230 231 while (flags) { 232 unsigned int i; 233 234 for (i = 0; (flags & chain_flags[i].flag) == 0; i++); 235 236 if (have_flag) 237 printf(","); 238 239 printf("%s", proto_to_name(chain_flags[i].proto,0)); 240 have_flag = 1; 241 242 flags &= ~chain_flags[i].flag; 243 } 244 245 if (!have_flag) 246 printf("NONE"); 247} 248 249/* Prints out the match */ 250static void ipv6header_print(const void *ip, 251 const struct xt_entry_match *match, int numeric) 252{ 253 const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data; 254 printf("ipv6header "); 255 256 if (info->matchflags || info->invflags) { 257 printf("flags:%s", info->invflags ? "!" : ""); 258 if (numeric) 259 printf("0x%02X ", info->matchflags); 260 else { 261 print_header(info->matchflags); 262 printf(" "); 263 } 264 } 265 266 if (info->modeflag) 267 printf("soft "); 268 269 return; 270} 271 272/* Saves the match */ 273static void ipv6header_save(const void *ip, const struct xt_entry_match *match) 274{ 275 276 const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data; 277 278 printf("--header "); 279 printf("%s", info->invflags ? "!" : ""); 280 print_header(info->matchflags); 281 printf(" "); 282 if (info->modeflag) 283 printf("--soft "); 284 285 return; 286} 287 288static struct xtables_match ipv6header_mt6_reg = { 289 .name = "ipv6header", 290 .version = XTABLES_VERSION, 291 .family = PF_INET6, 292 .size = XT_ALIGN(sizeof(struct ip6t_ipv6header_info)), 293 .userspacesize = XT_ALIGN(sizeof(struct ip6t_ipv6header_info)), 294 .help = ipv6header_help, 295 .init = ipv6header_init, 296 .parse = ipv6header_parse, 297 .final_check = ipv6header_check, 298 .print = ipv6header_print, 299 .save = ipv6header_save, 300 .extra_opts = ipv6header_opts, 301}; 302 303void _init(void) 304{ 305 xtables_register_match(&ipv6header_mt6_reg); 306} 307