libipt_realm.c revision d09b6d591ca7d7d7575cb6aa20384c9830f777ab
19258b6bc66e09368ada54001f619d53b4fc976d5ager@chromium.org/* Shared library add-on to iptables to add realm matching support. */ 29a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <stdbool.h> 39a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <stdio.h> 49a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <netdb.h> 59a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <string.h> 69a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <stdlib.h> 79a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <errno.h> 89a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <ctype.h> 99a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <getopt.h> 109a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#if defined(__GLIBC__) && __GLIBC__ == 2 119a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <net/ethernet.h> 129a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#else 139a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <linux/if_ether.h> 149a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#endif 159a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <xtables.h> 169a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com#include <linux/netfilter_ipv4/ipt_realm.h> 179a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com 189a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.comstatic void realm_help(void) 199a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com{ 209a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com printf( 219a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com"realm match options:\n" 229a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com"[!] --realm value[/mask]\n" 239a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com" Match realm\n"); 249a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com} 259a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com 269a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.comstatic const struct option realm_opts[] = { 279a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com {.name = "realm", .has_arg = true, .val = '1'}, 289a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com XT_GETOPT_TABLEEND, 299a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com}; 309a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com 319a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.comstruct realmname { 329a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com int id; 339a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com char* name; 349a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com int len; 359a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com struct realmname* next; 369a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com}; 379a4089a092cad9ff23b6416b92cd5d818dc101d1mads.s.ager@gmail.com 38/* array of realms from /etc/iproute2/rt_realms */ 39static struct realmname *realms; 40/* 1 if loading failed */ 41static int rdberr; 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 = 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 = 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 xtables_check_inverse(optarg, &invert, &optind, 0, argv); 161 end = optarg = optarg; 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 xtables_error(PARAMETER_PROBLEM, 170 "Bad realm value `%s'", optarg); 171 } else { 172 id = realm_name2id(optarg); 173 if (id == -1) 174 xtables_error(PARAMETER_PROBLEM, 175 "Realm `%s' not found", optarg); 176 realminfo->id = id; 177 realminfo->mask = 0xffffffff; 178 } 179 if (invert) 180 realminfo->invert = 1; 181 *flags = 1; 182 break; 183 } 184 return 1; 185} 186 187static void 188print_realm(unsigned long id, unsigned long mask, int numeric) 189{ 190 const char* name = NULL; 191 192 if (mask != 0xffffffff) 193 printf("0x%lx/0x%lx ", id, mask); 194 else { 195 if (numeric == 0) 196 name = realm_id2name(id); 197 if (name) 198 printf("%s ", name); 199 else 200 printf("0x%lx ", id); 201 } 202} 203 204static void realm_print(const void *ip, const struct xt_entry_match *match, 205 int numeric) 206{ 207 const struct ipt_realm_info *ri = (const void *)match->data; 208 209 if (ri->invert) 210 printf("! "); 211 212 printf("realm "); 213 print_realm(ri->id, ri->mask, numeric); 214} 215 216static void realm_save(const void *ip, const struct xt_entry_match *match) 217{ 218 const struct ipt_realm_info *ri = (const void *)match->data; 219 220 if (ri->invert) 221 printf("! "); 222 223 printf("--realm "); 224 print_realm(ri->id, ri->mask, 0); 225} 226 227static void realm_check(unsigned int flags) 228{ 229 if (!flags) 230 xtables_error(PARAMETER_PROBLEM, 231 "realm match: You must specify `--realm'"); 232} 233 234static struct xtables_match realm_mt_reg = { 235 .name = "realm", 236 .version = XTABLES_VERSION, 237 .family = NFPROTO_IPV4, 238 .size = XT_ALIGN(sizeof(struct ipt_realm_info)), 239 .userspacesize = XT_ALIGN(sizeof(struct ipt_realm_info)), 240 .help = realm_help, 241 .parse = realm_parse, 242 .final_check = realm_check, 243 .print = realm_print, 244 .save = realm_save, 245 .extra_opts = realm_opts, 246}; 247 248void _init(void) 249{ 250 xtables_register_match(&realm_mt_reg); 251} 252