1 /* Shared library add-on to ip6tables to add Fragmentation header support. */ 2 #include <stdio.h> 3 #include <netdb.h> 4 #include <string.h> 5 #include <stdlib.h> 6 #include <getopt.h> 7 #include <errno.h> 8 #include <ip6tables.h> 9 #include <linux/netfilter_ipv6/ip6t_frag.h> 10 11 /* Function which prints out usage message. */ 12 static void 13 help(void) 14 { 15 printf( 16 "FRAG v%s options:\n" 17 " --fragid [!] id[:id] match the id (range)\n" 18 " --fraglen [!] length total length of this header\n" 19 " --fragres check the reserved filed, too\n" 20 " --fragfirst matches on the first fragment\n" 21 " [--fragmore|--fraglast] there are more fragments or this\n" 22 " is the last one\n", 23 IPTABLES_VERSION); 24 } 25 26 static struct option opts[] = { 27 { .name = "fragid", .has_arg = 1, .flag = 0, .val = '1' }, 28 { .name = "fraglen", .has_arg = 1, .flag = 0, .val = '2' }, 29 { .name = "fragres", .has_arg = 0, .flag = 0, .val = '3' }, 30 { .name = "fragfirst", .has_arg = 0, .flag = 0, .val = '4' }, 31 { .name = "fragmore", .has_arg = 0, .flag = 0, .val = '5' }, 32 { .name = "fraglast", .has_arg = 0, .flag = 0, .val = '6' }, 33 { .name = 0 } 34 }; 35 36 static u_int32_t 37 parse_frag_id(const char *idstr, const char *typestr) 38 { 39 unsigned long int id; 40 char* ep; 41 42 id = strtoul(idstr, &ep, 0); 43 44 if ( idstr == ep ) { 45 exit_error(PARAMETER_PROBLEM, 46 "FRAG no valid digits in %s `%s'", typestr, idstr); 47 } 48 if ( id == ULONG_MAX && errno == ERANGE ) { 49 exit_error(PARAMETER_PROBLEM, 50 "%s `%s' specified too big: would overflow", 51 typestr, idstr); 52 } 53 if ( *idstr != '\0' && *ep != '\0' ) { 54 exit_error(PARAMETER_PROBLEM, 55 "FRAG error parsing %s `%s'", typestr, idstr); 56 } 57 return (u_int32_t) id; 58 } 59 60 static void 61 parse_frag_ids(const char *idstring, u_int32_t *ids) 62 { 63 char *buffer; 64 char *cp; 65 66 buffer = strdup(idstring); 67 if ((cp = strchr(buffer, ':')) == NULL) 68 ids[0] = ids[1] = parse_frag_id(buffer,"id"); 69 else { 70 *cp = '\0'; 71 cp++; 72 73 ids[0] = buffer[0] ? parse_frag_id(buffer,"id") : 0; 74 ids[1] = cp[0] ? parse_frag_id(cp,"id") : 0xFFFFFFFF; 75 } 76 free(buffer); 77 } 78 79 /* Initialize the match. */ 80 static void 81 init(struct ip6t_entry_match *m, unsigned int *nfcache) 82 { 83 struct ip6t_frag *fraginfo = (struct ip6t_frag *)m->data; 84 85 fraginfo->ids[0] = 0x0L; 86 fraginfo->ids[1] = 0xFFFFFFFF; 87 fraginfo->hdrlen = 0; 88 fraginfo->flags = 0; 89 fraginfo->invflags = 0; 90 } 91 92 /* Function which parses command options; returns true if it 93 ate an option */ 94 static int 95 parse(int c, char **argv, int invert, unsigned int *flags, 96 const struct ip6t_entry *entry, 97 unsigned int *nfcache, 98 struct ip6t_entry_match **match) 99 { 100 struct ip6t_frag *fraginfo = (struct ip6t_frag *)(*match)->data; 101 102 switch (c) { 103 case '1': 104 if (*flags & IP6T_FRAG_IDS) 105 exit_error(PARAMETER_PROBLEM, 106 "Only one `--fragid' allowed"); 107 check_inverse(optarg, &invert, &optind, 0); 108 parse_frag_ids(argv[optind-1], fraginfo->ids); 109 if (invert) 110 fraginfo->invflags |= IP6T_FRAG_INV_IDS; 111 fraginfo->flags |= IP6T_FRAG_IDS; 112 *flags |= IP6T_FRAG_IDS; 113 break; 114 case '2': 115 if (*flags & IP6T_FRAG_LEN) 116 exit_error(PARAMETER_PROBLEM, 117 "Only one `--fraglen' allowed"); 118 check_inverse(optarg, &invert, &optind, 0); 119 fraginfo->hdrlen = parse_frag_id(argv[optind-1], "length"); 120 if (invert) 121 fraginfo->invflags |= IP6T_FRAG_INV_LEN; 122 fraginfo->flags |= IP6T_FRAG_LEN; 123 *flags |= IP6T_FRAG_LEN; 124 break; 125 case '3': 126 if (*flags & IP6T_FRAG_RES) 127 exit_error(PARAMETER_PROBLEM, 128 "Only one `--fragres' allowed"); 129 fraginfo->flags |= IP6T_FRAG_RES; 130 *flags |= IP6T_FRAG_RES; 131 break; 132 case '4': 133 if (*flags & IP6T_FRAG_FST) 134 exit_error(PARAMETER_PROBLEM, 135 "Only one `--fragfirst' allowed"); 136 fraginfo->flags |= IP6T_FRAG_FST; 137 *flags |= IP6T_FRAG_FST; 138 break; 139 case '5': 140 if (*flags & (IP6T_FRAG_MF|IP6T_FRAG_NMF)) 141 exit_error(PARAMETER_PROBLEM, 142 "Only one `--fragmore' or `--fraglast' allowed"); 143 fraginfo->flags |= IP6T_FRAG_MF; 144 *flags |= IP6T_FRAG_MF; 145 break; 146 case '6': 147 if (*flags & (IP6T_FRAG_MF|IP6T_FRAG_NMF)) 148 exit_error(PARAMETER_PROBLEM, 149 "Only one `--fragmore' or `--fraglast' allowed"); 150 fraginfo->flags |= IP6T_FRAG_NMF; 151 *flags |= IP6T_FRAG_NMF; 152 break; 153 default: 154 return 0; 155 } 156 157 return 1; 158 } 159 160 /* Final check; we don't care. */ 161 static void 162 final_check(unsigned int flags) 163 { 164 } 165 166 static void 167 print_ids(const char *name, u_int32_t min, u_int32_t max, 168 int invert) 169 { 170 const char *inv = invert ? "!" : ""; 171 172 if (min != 0 || max != 0xFFFFFFFF || invert) { 173 printf("%s", name); 174 if (min == max) 175 printf(":%s%u ", inv, min); 176 else 177 printf("s:%s%u:%u ", inv, min, max); 178 } 179 } 180 181 /* Prints out the union ip6t_matchinfo. */ 182 static void 183 print(const struct ip6t_ip6 *ip, 184 const struct ip6t_entry_match *match, int numeric) 185 { 186 const struct ip6t_frag *frag = (struct ip6t_frag *)match->data; 187 188 printf("frag "); 189 print_ids("id", frag->ids[0], frag->ids[1], 190 frag->invflags & IP6T_FRAG_INV_IDS); 191 192 if (frag->flags & IP6T_FRAG_LEN) { 193 printf("length:%s%u ", 194 frag->invflags & IP6T_FRAG_INV_LEN ? "!" : "", 195 frag->hdrlen); 196 } 197 198 if (frag->flags & IP6T_FRAG_RES) 199 printf("reserved "); 200 201 if (frag->flags & IP6T_FRAG_FST) 202 printf("first "); 203 204 if (frag->flags & IP6T_FRAG_MF) 205 printf("more "); 206 207 if (frag->flags & IP6T_FRAG_NMF) 208 printf("last "); 209 210 if (frag->invflags & ~IP6T_FRAG_INV_MASK) 211 printf("Unknown invflags: 0x%X ", 212 frag->invflags & ~IP6T_FRAG_INV_MASK); 213 } 214 215 /* Saves the union ip6t_matchinfo in parsable form to stdout. */ 216 static void save(const struct ip6t_ip6 *ip, const struct ip6t_entry_match *match) 217 { 218 const struct ip6t_frag *fraginfo = (struct ip6t_frag *)match->data; 219 220 if (!(fraginfo->ids[0] == 0 221 && fraginfo->ids[1] == 0xFFFFFFFF)) { 222 printf("--fragid %s", 223 (fraginfo->invflags & IP6T_FRAG_INV_IDS) ? "! " : ""); 224 if (fraginfo->ids[0] 225 != fraginfo->ids[1]) 226 printf("%u:%u ", 227 fraginfo->ids[0], 228 fraginfo->ids[1]); 229 else 230 printf("%u ", 231 fraginfo->ids[0]); 232 } 233 234 if (fraginfo->flags & IP6T_FRAG_LEN) { 235 printf("--fraglen %s%u ", 236 (fraginfo->invflags & IP6T_FRAG_INV_LEN) ? "! " : "", 237 fraginfo->hdrlen); 238 } 239 240 if (fraginfo->flags & IP6T_FRAG_RES) 241 printf("--fragres "); 242 243 if (fraginfo->flags & IP6T_FRAG_FST) 244 printf("--fragfirst "); 245 246 if (fraginfo->flags & IP6T_FRAG_MF) 247 printf("--fragmore "); 248 249 if (fraginfo->flags & IP6T_FRAG_NMF) 250 printf("--fraglast "); 251 } 252 253 static 254 struct ip6tables_match frag = { 255 .name = "frag", 256 .version = IPTABLES_VERSION, 257 .size = IP6T_ALIGN(sizeof(struct ip6t_frag)), 258 .userspacesize = IP6T_ALIGN(sizeof(struct ip6t_frag)), 259 .help = &help, 260 .init = &init, 261 .parse = &parse, 262 .final_check = &final_check, 263 .print = &print, 264 .save = &save, 265 .extra_opts = opts 266 }; 267 268 void 269 _init(void) 270 { 271 register_match6(&frag); 272 } 273
