crda.c

   1 /*
   2  * Central Regulatory Domain Agent for Linux
   3  *
   4  * Userspace helper which sends regulatory domains to Linux via nl80211
   5  */
   6
   7 #include <errno.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <sys/mman.h>
  11 #include <sys/stat.h>
  12 #include <fcntl.h>
  13 #include <arpa/inet.h>
  14
  15 #include <netlink/genl/genl.h>
  16 #include <netlink/genl/family.h>
  17 #include <netlink/genl/ctrl.h>
  18 #include <netlink/msg.h>
  19 #include <netlink/attr.h>
  20 #include <linux/nl80211.h>
  21
  22 #include "regdb.h"
  23
  24 #ifdef USE_OPENSSL
  25 #include <openssl/objects.h>
  26 #include <openssl/bn.h>
  27 #include <openssl/rsa.h>
  28 #include <openssl/sha.h>
  29
  30 #include "keys-ssl.c"
  31 #endif
  32
  33 #ifdef USE_GCRYPT
  34 #include <gcrypt.h>
  35
  36 #include "keys-gcrypt.c"
  37 #endif
  38
  39 struct nl80211_state {
  40         struct nl_handle *nl_handle;
  41         struct nl_cache *nl_cache;
  42         struct genl_family *nl80211;
  43 };
  44
  45 static int nl80211_init(struct nl80211_state *state)
  46 {
  47         int err;
  48
  49         state->nl_handle = nl_handle_alloc();
  50         if (!state->nl_handle) {
  51                 fprintf(stderr, "Failed to allocate netlink handle.\n");
  52                 return -ENOMEM;
  53         }
  54
  55         if (genl_connect(state->nl_handle)) {
  56                 fprintf(stderr, "Failed to connect to generic netlink.\n");
  57                 err = -ENOLINK;
  58                 goto out_handle_destroy;
  59         }
  60
  61         state->nl_cache = genl_ctrl_alloc_cache(state->nl_handle);
  62         if (!state->nl_cache) {
  63                 fprintf(stderr, "Failed to allocate generic netlink cache.\n");
  64                 err = -ENOMEM;
  65                 goto out_handle_destroy;
  66         }
  67
  68         state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
  69         if (!state->nl80211) {
  70                 fprintf(stderr, "nl80211 not found.\n");
  71                 err = -ENOENT;
  72                 goto out_cache_free;
  73         }
  74
  75         return 0;
  76
  77  out_cache_free:
  78         nl_cache_free(state->nl_cache);
  79  out_handle_destroy:
  80         nl_handle_destroy(state->nl_handle);
  81         return err;
  82 }
  83
  84 static void nl80211_cleanup(struct nl80211_state *state)
  85 {
  86         genl_family_put(state->nl80211);
  87         nl_cache_free(state->nl_cache);
  88         nl_handle_destroy(state->nl_handle);
  89 }
  90
  91 static int reg_handler(struct nl_msg *msg, void *arg)
  92 {
  93         printf("=== reg_handler() called\n");
  94         return NL_SKIP;
  95 }
  96
  97 static int wait_handler(struct nl_msg *msg, void *arg)
  98 {
  99         int *finished = arg;
 100         *finished = 1;
 101         return NL_STOP;
 102 }
 103
 104
 105 static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg)
 106 {
 107         fprintf(stderr, "nl80211 error %d\n", err->error);
 108         exit(err->error);
 109 }
 110
 111 int isalpha_upper(char letter)
 112 {
 113         if (letter >= 65 && letter <= 90)
 114                 return 1;
 115         return 0;
 116 }
 117
 118 static int is_alpha2(char *alpha2)
 119 {
 120         if (isalpha_upper(alpha2[0]) && isalpha_upper(alpha2[1]))
 121                 return 1;
 122         return 0;
 123 }
 124
 125 static int is_world_regdom(char *alpha2)
 126 {
 127         /* ASCII 0 */
 128         if (alpha2[0] == 48 && alpha2[1] == 48)
 129                 return 1;
 130         return 0;
 131 }
 132
 133 static void *get_file_ptr(__u8 *db, int dblen, int structlen, __be32 ptr)
 134 {
 135         __u32 p = ntohl(ptr);
 136
 137         if (p > dblen - structlen) {
 138                 fprintf(stderr, "Invalid database file, bad pointer!\n");
 139                 exit(3);
 140         }
 141
 142         return (void *)(db + p);
 143 }
 144
 145 static int put_reg_rule(__u8 *db, int dblen, __be32 ruleptr, struct nl_msg *msg)
 146 {
 147         struct regdb_file_reg_rule *rule;
 148         struct regdb_file_freq_range *freq;
 149         struct regdb_file_power_rule *power;
 150
 151         rule    = get_file_ptr(db, dblen, sizeof(*rule), ruleptr);
 152         freq    = get_file_ptr(db, dblen, sizeof(*freq), rule->freq_range_ptr);
 153         power   = get_file_ptr(db, dblen, sizeof(*power), rule->power_rule_ptr);
 154
 155         NLA_PUT_U32(msg, NL80211_ATTR_REG_RULE_FLAGS,           ntohl(rule->flags));
 156         NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_START,         ntohl(freq->start_freq));
 157         NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_END,           ntohl(freq->end_freq));
 158         NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_MAX_BW,        ntohl(freq->max_bandwidth));
 159         NLA_PUT_U32(msg, NL80211_ATTR_POWER_RULE_MAX_ANT_GAIN,  ntohl(power->max_antenna_gain));
 160         NLA_PUT_U32(msg, NL80211_ATTR_POWER_RULE_MAX_EIRP,      ntohl(power->max_eirp));
 161
 162         return 0;
 163
 164 nla_put_failure:
 165         return -1;
 166 }
 167
 168 int main(int argc, char **argv)
 169 {
 170         int fd;
 171         struct stat stat;
 172         __u8 *db;
 173         struct regdb_file_header *header;
 174         struct regdb_file_reg_country *countries;
 175         int dblen, siglen, num_countries, i, j, r;
 176         char alpha2[2];
 177         char *env_country;
 178         struct nl80211_state nlstate;
 179         struct nl_cb *cb = NULL;
 180         struct nl_msg *msg;
 181         int found_country = 0;
 182         int finished = 0;
 183
 184         struct regdb_file_reg_rules_collection *rcoll;
 185         struct regdb_file_reg_country *country;
 186         struct nlattr *nl_reg_rules;
 187         int num_rules;
 188
 189 #ifdef USE_OPENSSL
 190         RSA *rsa;
 191         __u8 hash[SHA_DIGEST_LENGTH];
 192         int ok = 0;
 193 #endif
 194 #ifdef USE_GCRYPT
 195         gcry_mpi_t mpi_e, mpi_n;
 196         gcry_sexp_t rsa, signature, data;
 197         __u8 hash[20];
 198         int ok = 0;
 199 #endif
 200         char *regdb = "/usr/lib/crda/regulatory.bin";
 201
 202         if (argc != 1) {
 203                 fprintf(stderr, "Usage: %s\n", argv[0]);
 204                 return -EINVAL;
 205         }
 206
 207         env_country = getenv("COUNTRY");
 208         if (!env_country) {
 209                 fprintf(stderr, "COUNTRY environment variable not set.\n");
 210                 return -EINVAL;
 211         }
 212
 213
 214         if (!is_alpha2(env_country) && !is_world_regdom(env_country)) {
 215                 fprintf(stderr, "Invalid alpha2 set in COUNTRY\n");
 216                 return -EINVAL;
 217         }
 218
 219         memcpy(alpha2, env_country, 2);
 220
 221         r = nl80211_init(&nlstate);
 222         if (r)
 223                 return -EIO;
 224
 225         fd = open(regdb, O_RDONLY);
 226         if (fd < 0) {
 227                 perror("failed to open db file");
 228                 r = -ENOENT;
 229                 goto out;
 230         }
 231
 232         if (fstat(fd, &stat)) {
 233                 perror("failed to fstat db file");
 234                 r = -EIO;
 235                 goto out;
 236         }
 237
 238         dblen = stat.st_size;
 239
 240         db = mmap(NULL, dblen, PROT_READ, MAP_PRIVATE, fd, 0);
 241         if (db == MAP_FAILED) {
 242                 perror("failed to mmap db file");
 243                 r = -EIO;
 244                 goto out;
 245         }
 246
 247         header = get_file_ptr(db, dblen, sizeof(*header), 0);
 248
 249         if (ntohl(header->magic) != REGDB_MAGIC) {
 250                 fprintf(stderr, "Invalid database magic\n");
 251                 r = -EINVAL;
 252                 goto out;
 253         }
 254
 255         if (ntohl(header->version) != REGDB_VERSION) {
 256                 fprintf(stderr, "Invalid database version\n");
 257                 r = -EINVAL;
 258                 goto out;
 259         }
 260
 261         siglen = ntohl(header->signature_length);
 262         /* adjust dblen so later sanity checks don't run into the signature */
 263         dblen -= siglen;
 264
 265         if (dblen <= sizeof(*header)) {
 266                 fprintf(stderr, "Invalid signature length %d\n", siglen);
 267                 r = -EINVAL;
 268                 goto out;
 269         }
 270
 271         /* verify signature */
 272 #ifdef USE_OPENSSL
 273         rsa = RSA_new();
 274         if (!rsa) {
 275                 fprintf(stderr, "Failed to create RSA key\n");
 276                 r = -EINVAL;
 277                 goto out;
 278         }
 279
 280         if (SHA1(db, dblen, hash) != hash) {
 281                 fprintf(stderr, "Failed to calculate SHA sum\n");
 282                 r = -EINVAL;
 283                 goto out;
 284         }
 285
 286         for (i = 0; i < sizeof(keys)/sizeof(keys[0]); i++) {
 287                 rsa->e = &keys[i].e;
 288                 rsa->n = &keys[i].n;
 289
 290                 if (RSA_size(rsa) != siglen)
 291                         continue;
 292
 293                 ok = RSA_verify(NID_sha1, hash, SHA_DIGEST_LENGTH,
 294                                 db + dblen, siglen, rsa) == 1;
 295                 if (ok)
 296                         break;
 297         }
 298
 299         if (!ok) {
 300                 fprintf(stderr, "Database signature wrong\n");
 301                 r = -EINVAL;
 302                 goto out;
 303         }
 304
 305         rsa->e = NULL;
 306         rsa->n = NULL;
 307         RSA_free(rsa);
 308
 309         BN_print_fp(stdout, &keys[0].n);
 310
 311 #endif
 312
 313 #ifdef USE_GCRYPT
 314         /* hash the db */
 315         gcry_md_hash_buffer(GCRY_MD_SHA1, hash, db, dblen);
 316
 317         if (gcry_sexp_build(&data, NULL, "(data (flags pkcs1) (hash sha1 %b))",
 318                             20, hash)) {
 319                 fprintf(stderr, "failed to build data expression\n");
 320                 return 2;
 321         }
 322
 323         if (gcry_sexp_build(&signature, NULL, "(sig-val (rsa (s %b)))",
 324                             siglen, db + dblen)) {
 325                 fprintf(stderr, "failed to build signature expression\n");
 326                 return 2;
 327         }
 328
 329         for (i = 0; i < sizeof(keys)/sizeof(keys[0]); i++) {
 330                 if (gcry_mpi_scan(&mpi_e, GCRYMPI_FMT_USG,
 331                                   keys[0].e, keys[0].len_e, NULL) ||
 332                     gcry_mpi_scan(&mpi_n, GCRYMPI_FMT_USG,
 333                                   keys[0].n, keys[0].len_n, NULL)) {
 334                         fprintf(stderr, "failed to convert numbers\n");
 335                         return 2;
 336                 }
 337
 338                 if (gcry_sexp_build(&rsa, NULL,
 339                                     "(public-key (rsa (n %m) (e %m)))",
 340                                     mpi_n, mpi_e)) {
 341                         fprintf(stderr, "failed to build rsa key\n");
 342                         return 2;
 343                 }
 344
 345                 if (!gcry_pk_verify(signature, data, rsa)) {
 346                         ok = 1;
 347                         break;
 348                 }
 349         }
 350
 351         if (!ok) {
 352                 fprintf(stderr, "Database signature wrong\n");
 353                 return 2;
 354         }
 355
 356 #endif
 357
 358         num_countries = ntohl(header->reg_country_num);
 359         countries = get_file_ptr(db, dblen,
 360                                  sizeof(struct regdb_file_reg_country) * num_countries,
 361                                  header->reg_country_ptr);
 362
 363         for (i = 0; i < num_countries; i++) {
 364                 country = countries + i;
 365                 if (memcmp(country->alpha2, alpha2, 2) == 0) {
 366                         found_country = 1;
 367                         break;
 368                 }
 369         }
 370
 371         if (!found_country) {
 372                 fprintf(stderr, "failed to find a country match in regulatory database\n");
 373                 return -1;
 374         }
 375
 376         msg = nlmsg_alloc();
 377         if (!msg) {
 378                 fprintf(stderr, "failed to allocate netlink msg\n");
 379                 return -1;
 380         }
 381
 382         genlmsg_put(msg, 0, 0, genl_family_get_id(nlstate.nl80211), 0,
 383                 0, NL80211_CMD_SET_REG, 0);
 384
 385
 386         rcoll = get_file_ptr(db, dblen, sizeof(*rcoll), country->reg_collection_ptr);
 387         num_rules = ntohl(rcoll->reg_rule_num);
 388         /* re-get pointer with sanity checking for num_rules */
 389         rcoll = get_file_ptr(db, dblen,
 390                              sizeof(*rcoll) + num_rules * sizeof(__be32),
 391                              country->reg_collection_ptr);
 392
 393         NLA_PUT_STRING(msg, NL80211_ATTR_REG_ALPHA2, (char *) country->alpha2);
 394
 395         nl_reg_rules = nla_nest_start(msg, NL80211_ATTR_REG_RULES);
 396         if (!nl_reg_rules) {
 397                 r = -1;
 398                 goto nla_put_failure;
 399         }
 400
 401         for (j = 0; j < num_rules; j++) {
 402                 struct nlattr *nl_reg_rule;
 403                 nl_reg_rule = nla_nest_start(msg, i);
 404                 if (!nl_reg_rule)
 405                         goto nla_put_failure;
 406
 407                 r = put_reg_rule(db, dblen, rcoll->reg_rule_ptrs[j], msg);
 408                 if (r)
 409                         goto nla_put_failure;
 410
 411                 nla_nest_end(msg, nl_reg_rule);
 412         }
 413
 414         nla_nest_end(msg, nl_reg_rules);
 415
 416         cb = nl_cb_alloc(NL_CB_CUSTOM);
 417         if (!cb)
 418                 goto cb_out;
 419
 420         r = nl_send_auto_complete(nlstate.nl_handle, msg);
 421
 422         if (r < 0) {
 423                 fprintf(stderr, "failed to send regulatory request: %d\n", r);
 424                 goto cb_out;
 425         }
 426
 427         nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, reg_handler, NULL);
 428         nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, wait_handler, &finished);
 429         nl_cb_err(cb, NL_CB_CUSTOM, error_handler, NULL);
 430
 431         if (!finished) {
 432                 r = nl_wait_for_ack(nlstate.nl_handle);
 433                 if (r < 0) {
 434                         fprintf(stderr, "failed to set regulatory domain: %d\n", r);
 435                         goto cb_out;
 436                 }
 437         }
 438
 439 cb_out:
 440         nl_cb_put(cb);
 441 nla_put_failure:
 442         nlmsg_free(msg);
 443 out:
 444         nl80211_cleanup(&nlstate);
 445         return r;
 446 }