libipt_realm.c revision ddac6c5bc636003d664d25c08ea3fe176565096c
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 17static void realm_help(void) 18{ 19 printf( 20"realm match options:\n" 21"[!] --realm value[/mask]\n" 22" Match realm\n"); 23} 24 25static const struct option realm_opts[] = { 26 { "realm", 1, NULL, '1' }, 27 { .name = NULL } 28}; 29 30struct realmname { 31 int id; 32 char* name; 33 int len; 34 struct realmname* next; 35}; 36 37/* array of realms from /etc/iproute2/rt_realms */ 38static struct realmname *realms = NULL; 39/* 1 if loading failed */ 40static int rdberr = 0; 41 42 43static void load_realms(void) 44{ 45 const char* rfnm = "/etc/iproute2/rt_realms"; 46 char buf[512]; 47 FILE *fil; 48 char *cur, *nxt; 49 int id; 50 struct realmname *oldnm = NULL, *newnm = NULL; 51 52 fil = fopen(rfnm, "r"); 53 if (!fil) { 54 rdberr = 1; 55 return; 56 } 57 58 while (fgets(buf, sizeof(buf), fil)) { 59 cur = buf; 60 while ((*cur == ' ') || (*cur == '\t')) 61 cur++; 62 if ((*cur == '#') || (*cur == '\n') || (*cur == 0)) 63 continue; 64 65 /* iproute2 allows hex and dec format */ 66 errno = 0; 67 id = strtoul(cur, &nxt, strncmp(cur, "0x", 2) ? 10 : 16); 68 if ((nxt == cur) || errno) 69 continue; 70 71 /* same boundaries as in iproute2 */ 72 if (id < 0 || id > 255) 73 continue; 74 cur = nxt; 75 76 if (!isspace(*cur)) 77 continue; 78 while ((*cur == ' ') || (*cur == '\t')) 79 cur++; 80 if ((*cur == '#') || (*cur == '\n') || (*cur == 0)) 81 continue; 82 nxt = cur; 83 while ((*nxt != 0) && !isspace(*nxt)) 84 nxt++; 85 if (nxt == cur) 86 continue; 87 88 /* found valid data */ 89 newnm = (struct realmname*)malloc(sizeof(struct realmname)); 90 if (newnm == NULL) { 91 perror("libipt_realm: malloc failed"); 92 exit(1); 93 } 94 newnm->id = id; 95 newnm->len = nxt - cur; 96 newnm->name = (char*)malloc(newnm->len + 1); 97 if (newnm->name == NULL) { 98 perror("libipt_realm: malloc failed"); 99 exit(1); 100 } 101 strncpy(newnm->name, cur, newnm->len); 102 newnm->name[newnm->len] = 0; 103 newnm->next = NULL; 104 105 if (oldnm) 106 oldnm->next = newnm; 107 else 108 realms = newnm; 109 oldnm = newnm; 110 } 111 112 fclose(fil); 113} 114 115/* get realm id for name, -1 if error/not found */ 116static int realm_name2id(const char* name) 117{ 118 struct realmname* cur; 119 120 if ((realms == NULL) && (rdberr == 0)) 121 load_realms(); 122 cur = realms; 123 if (cur == NULL) 124 return -1; 125 while (cur) { 126 if (!strncmp(name, cur->name, cur->len + 1)) 127 return cur->id; 128 cur = cur->next; 129 } 130 return -1; 131} 132 133/* get realm name for id, NULL if error/not found */ 134static const char *realm_id2name(int id) 135{ 136 struct realmname* cur; 137 138 if ((realms == NULL) && (rdberr == 0)) 139 load_realms(); 140 cur = realms; 141 if (cur == NULL) 142 return NULL; 143 while (cur) { 144 if (id == cur->id) 145 return cur->name; 146 cur = cur->next; 147 } 148 return NULL; 149} 150 151static int realm_parse(int c, char **argv, int invert, unsigned int *flags, 152 const void *entry, struct xt_entry_match **match) 153{ 154 struct ipt_realm_info *realminfo = (struct ipt_realm_info *)(*match)->data; 155 int id; 156 157 switch (c) { 158 char *end; 159 case '1': 160 check_inverse(argv[optind-1], &invert, &optind, 0); 161 end = optarg = argv[optind-1]; 162 realminfo->id = strtoul(optarg, &end, 0); 163 if (end != optarg && (*end == '/' || *end == '\0')) { 164 if (*end == '/') 165 realminfo->mask = strtoul(end+1, &end, 0); 166 else 167 realminfo->mask = 0xffffffff; 168 if (*end != '\0' || end == optarg) 169 exit_error(PARAMETER_PROBLEM, 170 "Bad realm value `%s'", optarg); 171 } else { 172 id = realm_name2id(optarg); 173 if (id == -1) 174 exit_error(PARAMETER_PROBLEM, 175 "Realm `%s' not found", optarg); 176 realminfo->id = (u_int32_t)id; 177 realminfo->mask = 0xffffffff; 178 } 179 if (invert) 180 realminfo->invert = 1; 181 *flags = 1; 182 break; 183 184 default: 185 return 0; 186 } 187 return 1; 188} 189 190static void 191print_realm(unsigned long id, unsigned long mask, int numeric) 192{ 193 const char* name = NULL; 194 195 if (mask != 0xffffffff) 196 printf("0x%lx/0x%lx ", id, mask); 197 else { 198 if (numeric == 0) 199 name = realm_id2name(id); 200 if (name) 201 printf("%s ", name); 202 else 203 printf("0x%lx ", id); 204 } 205} 206 207static void realm_print(const void *ip, const struct xt_entry_match *match, 208 int numeric) 209{ 210 struct ipt_realm_info *ri = (struct ipt_realm_info *) match->data; 211 212 if (ri->invert) 213 printf("! "); 214 215 printf("realm "); 216 print_realm(ri->id, ri->mask, numeric); 217} 218 219static void realm_save(const void *ip, const struct xt_entry_match *match) 220{ 221 struct ipt_realm_info *ri = (struct ipt_realm_info *) match->data; 222 223 if (ri->invert) 224 printf("! "); 225 226 printf("--realm "); 227 print_realm(ri->id, ri->mask, 0); 228} 229 230static void realm_check(unsigned int flags) 231{ 232 if (!flags) 233 exit_error(PARAMETER_PROBLEM, 234 "realm match: You must specify `--realm'"); 235} 236 237static struct xtables_match realm_mt_reg = { 238 .name = "realm", 239 .version = XTABLES_VERSION, 240 .family = PF_INET, 241 .size = XT_ALIGN(sizeof(struct ipt_realm_info)), 242 .userspacesize = XT_ALIGN(sizeof(struct ipt_realm_info)), 243 .help = realm_help, 244 .parse = realm_parse, 245 .final_check = realm_check, 246 .print = realm_print, 247 .save = realm_save, 248 .extra_opts = realm_opts, 249}; 250 251void _init(void) 252{ 253 xtables_register_match(&realm_mt_reg); 254} 255