libipt_realm.c revision 967279231a9ecfa99f26694a954afc535c63db1d
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. */ 18static void realm_help(void) 19{ 20 printf( 21"realm match options:\n" 22"[!] --realm value[/mask]\n" 23" Match realm\n"); 24} 25 26static const struct option realm_opts[] = { 27 { "realm", 1, NULL, '1' }, 28 { .name = NULL } 29}; 30 31struct realmname { 32 int id; 33 char* name; 34 int len; 35 struct realmname* next; 36}; 37 38/* array of realms from /etc/iproute2/rt_realms */ 39static struct realmname *realms = NULL; 40/* 1 if loading failed */ 41static int rdberr = 0; 42 43 44static void load_realms(void) 45{ 46 const char* rfnm = "/etc/iproute2/rt_realms"; 47 char buf[512]; 48 FILE *fil; 49 char *cur, *nxt; 50 int id; 51 struct realmname *oldnm = NULL, *newnm = NULL; 52 53 fil = fopen(rfnm, "r"); 54 if (!fil) { 55 rdberr = 1; 56 return; 57 } 58 59 while (fgets(buf, sizeof(buf), fil)) { 60 cur = buf; 61 while ((*cur == ' ') || (*cur == '\t')) 62 cur++; 63 if ((*cur == '#') || (*cur == '\n') || (*cur == 0)) 64 continue; 65 66 /* iproute2 allows hex and dec format */ 67 errno = 0; 68 id = strtoul(cur, &nxt, strncmp(cur, "0x", 2) ? 10 : 16); 69 if ((nxt == cur) || errno) 70 continue; 71 72 /* same boundaries as in iproute2 */ 73 if (id < 0 || id > 255) 74 continue; 75 cur = nxt; 76 77 if (!isspace(*cur)) 78 continue; 79 while ((*cur == ' ') || (*cur == '\t')) 80 cur++; 81 if ((*cur == '#') || (*cur == '\n') || (*cur == 0)) 82 continue; 83 nxt = cur; 84 while ((*nxt != 0) && !isspace(*nxt)) 85 nxt++; 86 if (nxt == cur) 87 continue; 88 89 /* found valid data */ 90 newnm = (struct realmname*)malloc(sizeof(struct realmname)); 91 if (newnm == NULL) { 92 perror("libipt_realm: malloc failed"); 93 exit(1); 94 } 95 newnm->id = id; 96 newnm->len = nxt - cur; 97 newnm->name = (char*)malloc(newnm->len + 1); 98 if (newnm->name == NULL) { 99 perror("libipt_realm: malloc failed"); 100 exit(1); 101 } 102 strncpy(newnm->name, cur, newnm->len); 103 newnm->name[newnm->len] = 0; 104 newnm->next = NULL; 105 106 if (oldnm) 107 oldnm->next = newnm; 108 else 109 realms = newnm; 110 oldnm = newnm; 111 } 112 113 fclose(fil); 114} 115 116/* get realm id for name, -1 if error/not found */ 117static int realm_name2id(const char* name) 118{ 119 struct realmname* cur; 120 121 if ((realms == NULL) && (rdberr == 0)) 122 load_realms(); 123 cur = realms; 124 if (cur == NULL) 125 return -1; 126 while (cur) { 127 if (!strncmp(name, cur->name, cur->len + 1)) 128 return cur->id; 129 cur = cur->next; 130 } 131 return -1; 132} 133 134/* get realm name for id, NULL if error/not found */ 135static const char *realm_id2name(int id) 136{ 137 struct realmname* cur; 138 139 if ((realms == NULL) && (rdberr == 0)) 140 load_realms(); 141 cur = realms; 142 if (cur == NULL) 143 return NULL; 144 while (cur) { 145 if (id == cur->id) 146 return cur->name; 147 cur = cur->next; 148 } 149 return NULL; 150} 151 152 153/* Function which parses command options; returns true if it 154 ate an option */ 155static int realm_parse(int c, char **argv, int invert, unsigned int *flags, 156 const void *entry, struct xt_entry_match **match) 157{ 158 struct ipt_realm_info *realminfo = (struct ipt_realm_info *)(*match)->data; 159 int id; 160 161 switch (c) { 162 char *end; 163 case '1': 164 check_inverse(argv[optind-1], &invert, &optind, 0); 165 end = optarg = argv[optind-1]; 166 realminfo->id = strtoul(optarg, &end, 0); 167 if (end != optarg && (*end == '/' || *end == '\0')) { 168 if (*end == '/') 169 realminfo->mask = strtoul(end+1, &end, 0); 170 else 171 realminfo->mask = 0xffffffff; 172 if (*end != '\0' || end == optarg) 173 exit_error(PARAMETER_PROBLEM, 174 "Bad realm value `%s'", optarg); 175 } else { 176 id = realm_name2id(optarg); 177 if (id == -1) 178 exit_error(PARAMETER_PROBLEM, 179 "Realm `%s' not found", optarg); 180 realminfo->id = (u_int32_t)id; 181 realminfo->mask = 0xffffffff; 182 } 183 if (invert) 184 realminfo->invert = 1; 185 *flags = 1; 186 break; 187 188 default: 189 return 0; 190 } 191 return 1; 192} 193 194static void 195print_realm(unsigned long id, unsigned long mask, int numeric) 196{ 197 const char* name = NULL; 198 199 if (mask != 0xffffffff) 200 printf("0x%lx/0x%lx ", id, mask); 201 else { 202 if (numeric == 0) 203 name = realm_id2name(id); 204 if (name) 205 printf("%s ", name); 206 else 207 printf("0x%lx ", id); 208 } 209} 210 211/* Prints out the matchinfo. */ 212static void realm_print(const void *ip, const struct xt_entry_match *match, 213 int numeric) 214{ 215 struct ipt_realm_info *ri = (struct ipt_realm_info *) match->data; 216 217 if (ri->invert) 218 printf("! "); 219 220 printf("realm "); 221 print_realm(ri->id, ri->mask, numeric); 222} 223 224 225/* Saves the union ipt_matchinfo in parsable form to stdout. */ 226static void realm_save(const void *ip, const struct xt_entry_match *match) 227{ 228 struct ipt_realm_info *ri = (struct ipt_realm_info *) match->data; 229 230 if (ri->invert) 231 printf("! "); 232 233 printf("--realm "); 234 print_realm(ri->id, ri->mask, 0); 235} 236 237/* Final check; must have specified --mark. */ 238static void realm_check(unsigned int flags) 239{ 240 if (!flags) 241 exit_error(PARAMETER_PROBLEM, 242 "realm match: You must specify `--realm'"); 243} 244 245static struct xtables_match realm_mt_reg = { 246 .name = "realm", 247 .version = XTABLES_VERSION, 248 .family = PF_INET, 249 .size = XT_ALIGN(sizeof(struct ipt_realm_info)), 250 .userspacesize = XT_ALIGN(sizeof(struct ipt_realm_info)), 251 .help = realm_help, 252 .parse = realm_parse, 253 .final_check = realm_check, 254 .print = realm_print, 255 .save = realm_save, 256 .extra_opts = realm_opts, 257}; 258 259void _init(void) 260{ 261 xtables_register_match(&realm_mt_reg); 262} 263 264 265