1 /* Shared library add-on to iptables to add realm matching support. */ 2 #include <stdio.h> 3 #include <netdb.h> 4 #include <string.h> 5 #include <stdlib.h> 6 #include <errno.h> 7 #include <ctype.h> 8 #include <getopt.h> 9 #if defined(__GLIBC__) && __GLIBC__ == 2 10 #include <net/ethernet.h> 11 #else 12 #include <linux/if_ether.h> 13 #endif 14 #include <iptables.h> 15 #include <linux/netfilter_ipv4/ipt_realm.h> 16 17 /* Function which prints out usage message. */ 18 static void 19 help(void) 20 { 21 printf( 22 "realm v%s options:\n" 23 " --realm [!] value[/mask]\n" 24 " Match realm\n" 25 "\n", IPTABLES_VERSION); 26 } 27 28 static struct option opts[] = { 29 { "realm", 1, 0, '1' }, 30 {0} 31 }; 32 33 struct realmname { 34 int id; 35 char* name; 36 int len; 37 struct realmname* next; 38 }; 39 40 /* array of realms from /etc/iproute2/rt_realms */ 41 static struct realmname *realms = NULL; 42 /* 1 if loading failed */ 43 static int rdberr = 0; 44 45 46 void load_realms() 47 { 48 const char* rfnm = "/etc/iproute2/rt_realms"; 49 char buf[512]; 50 FILE *fil; 51 char *cur, *nxt; 52 int id; 53 struct realmname *oldnm = NULL, *newnm = NULL; 54 55 fil = fopen(rfnm, "r"); 56 if (!fil) { 57 rdberr = 1; 58 return; 59 } 60 61 while (fgets(buf, sizeof(buf), fil)) { 62 cur = buf; 63 while ((*cur == ' ') || (*cur == '\t')) 64 cur++; 65 if ((*cur == '#') || (*cur == '\n') || (*cur == 0)) 66 continue; 67 68 /* iproute2 allows hex and dec format */ 69 errno = 0; 70 id = strtoul(cur, &nxt, strncmp(cur, "0x", 2) ? 10 : 16); 71 if ((nxt == cur) || errno) 72 continue; 73 74 /* same boundaries as in iproute2 */ 75 if (id < 0 || id > 255) 76 continue; 77 cur = nxt; 78 79 if (!isspace(*cur)) 80 continue; 81 while ((*cur == ' ') || (*cur == '\t')) 82 cur++; 83 if ((*cur == '#') || (*cur == '\n') || (*cur == 0)) 84 continue; 85 nxt = cur; 86 while ((*nxt != 0) && !isspace(*nxt)) 87 nxt++; 88 if (nxt == cur) 89 continue; 90 91 /* found valid data */ 92 newnm = (struct realmname*)malloc(sizeof(struct realmname)); 93 if (newnm == NULL) { 94 perror("libipt_realm: malloc failed"); 95 exit(1); 96 } 97 newnm->id = id; 98 newnm->len = nxt - cur; 99 newnm->name = (char*)malloc(newnm->len + 1); 100 if (newnm->name == NULL) { 101 perror("libipt_realm: malloc failed"); 102 exit(1); 103 } 104 strncpy(newnm->name, cur, newnm->len); 105 newnm->name[newnm->len] = 0; 106 newnm->next = NULL; 107 108 if (oldnm) 109 oldnm->next = newnm; 110 else 111 realms = newnm; 112 oldnm = newnm; 113 } 114 115 fclose(fil); 116 } 117 118 /* get realm id for name, -1 if error/not found */ 119 int realm_name2id(const char* name) 120 { 121 struct realmname* cur; 122 123 if ((realms == NULL) && (rdberr == 0)) 124 load_realms(); 125 cur = realms; 126 if (cur == NULL) 127 return -1; 128 while (cur) { 129 if (!strncmp(name, cur->name, cur->len + 1)) 130 return cur->id; 131 cur = cur->next; 132 } 133 return -1; 134 } 135 136 /* get realm name for id, NULL if error/not found */ 137 const char* realm_id2name(int id) 138 { 139 struct realmname* cur; 140 141 if ((realms == NULL) && (rdberr == 0)) 142 load_realms(); 143 cur = realms; 144 if (cur == NULL) 145 return NULL; 146 while (cur) { 147 if (id == cur->id) 148 return cur->name; 149 cur = cur->next; 150 } 151 return NULL; 152 } 153 154 155 /* Function which parses command options; returns true if it 156 ate an option */ 157 static int 158 parse(int c, char **argv, int invert, unsigned int *flags, 159 const struct ipt_entry *entry, 160 unsigned int *nfcache, 161 struct ipt_entry_match **match) 162 { 163 struct ipt_realm_info *realminfo = (struct ipt_realm_info *)(*match)->data; 164 int id; 165 166 switch (c) { 167 char *end; 168 case '1': 169 check_inverse(argv[optind-1], &invert, &optind, 0); 170 end = optarg = argv[optind-1]; 171 realminfo->id = strtoul(optarg, &end, 0); 172 if (end != optarg && (*end == '/' || *end == '\0')) { 173 if (*end == '/') 174 realminfo->mask = strtoul(end+1, &end, 0); 175 else 176 realminfo->mask = 0xffffffff; 177 if (*end != '\0' || end == optarg) 178 exit_error(PARAMETER_PROBLEM, 179 "Bad realm value `%s'", optarg); 180 } else { 181 id = realm_name2id(optarg); 182 if (id == -1) 183 exit_error(PARAMETER_PROBLEM, 184 "Realm `%s' not found", optarg); 185 realminfo->id = (u_int32_t)id; 186 realminfo->mask = 0xffffffff; 187 } 188 if (invert) 189 realminfo->invert = 1; 190 *flags = 1; 191 break; 192 193 default: 194 return 0; 195 } 196 return 1; 197 } 198 199 static void 200 print_realm(unsigned long id, unsigned long mask, int numeric) 201 { 202 const char* name = NULL; 203 204 if (mask != 0xffffffff) 205 printf("0x%lx/0x%lx ", id, mask); 206 else { 207 if (numeric == 0) 208 name = realm_id2name(id); 209 if (name) 210 printf("%s ", name); 211 else 212 printf("0x%lx ", id); 213 } 214 } 215 216 /* Prints out the matchinfo. */ 217 static void 218 print(const struct ipt_ip *ip, 219 const struct ipt_entry_match *match, 220 int numeric) 221 { 222 struct ipt_realm_info *ri = (struct ipt_realm_info *) match->data; 223 224 if (ri->invert) 225 printf("! "); 226 227 printf("realm "); 228 print_realm(ri->id, ri->mask, numeric); 229 } 230 231 232 /* Saves the union ipt_matchinfo in parsable form to stdout. */ 233 static void 234 save(const struct ipt_ip *ip, const struct ipt_entry_match *match) 235 { 236 struct ipt_realm_info *ri = (struct ipt_realm_info *) match->data; 237 238 if (ri->invert) 239 printf("! "); 240 241 printf("--realm "); 242 print_realm(ri->id, ri->mask, 0); 243 } 244 245 /* Final check; must have specified --mark. */ 246 static void 247 final_check(unsigned int flags) 248 { 249 if (!flags) 250 exit_error(PARAMETER_PROBLEM, 251 "realm match: You must specify `--realm'"); 252 } 253 254 static struct iptables_match realm = { NULL, 255 .name = "realm", 256 .version = IPTABLES_VERSION, 257 .size = IPT_ALIGN(sizeof(struct ipt_realm_info)), 258 .userspacesize = IPT_ALIGN(sizeof(struct ipt_realm_info)), 259 .help = &help, 260 .parse = &parse, 261 .final_check = &final_check, 262 .print = &print, 263 .save = &save, 264 .extra_opts = opts 265 }; 266 267 void ipt_realm_init(void) 268 { 269 register_match(&realm); 270 } 271 272 273
