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
 201         char *regdb = "/usr/lib/crda/regulatory.bin";
 202
 203         if (argc != 1) {
 204                 fprintf(stderr, "Usage: %s\n", argv[0]);
 205                 return -EINVAL;
 206         }
 207
 208         env_country = getenv("COUNTRY");
 209         if (!env_country) {
 210                 fprintf(stderr, "COUNTRY environment variable not set.\n");
 211                 return -EINVAL;
 212         }
 213
 214
 215         if (!is_alpha2(env_country) && !is_world_regdom(env_country)) {
 216                 fprintf(stderr, "Invalid alpha2 set in COUNTRY\n");
 217                 return -EINVAL;
 218         }
 219
 220         memcpy(alpha2, env_country, 2);
 221
 222         r = nl80211_init(&nlstate);
 223         if (r)
 224                 return -EIO;
 225
 226         fd = open(regdb, O_RDONLY);
 227         if (fd < 0) {
 228                 perror("failed to open db file");
 229                 r = -ENOENT;
 230                 goto out;
 231         }
 232
 233         if (fstat(fd, &stat)) {
 234                 perror("failed to fstat db file");
 235                 r = -EIO;
 236                 goto out;
 237         }
 238
 239         dblen = stat.st_size;
 240
 241         db = mmap(NULL, dblen, PROT_READ, MAP_PRIVATE, fd, 0);
 242         if (db == MAP_FAILED) {
 243                 perror("failed to mmap db file");
 244                 r = -EIO;
 245                 goto out;
 246         }
 247
 248         header = get_file_ptr(db, dblen, sizeof(*header), 0);
 249
 250         if (ntohl(header->magic) != REGDB_MAGIC) {
 251                 fprintf(stderr, "Invalid database magic\n");
 252                 r = -EINVAL;
 253                 goto out;
 254         }
 255
 256         if (ntohl(header->version) != REGDB_VERSION) {
 257                 fprintf(stderr, "Invalid database version\n");
 258                 r = -EINVAL;
 259                 goto out;
 260         }
 261
 262         siglen = ntohl(header->signature_length);
 263         /* adjust dblen so later sanity checks don't run into the signature */
 264         dblen -= siglen;
 265
 266         if (dblen <= sizeof(*header)) {
 267                 fprintf(stderr, "Invalid signature length %d\n", siglen);
 268                 r = -EINVAL;
 269                 goto out;
 270         }
 271
 272         /* verify signature */
 273 #ifdef USE_OPENSSL
 274         rsa = RSA_new();
 275         if (!rsa) {
 276                 fprintf(stderr, "Failed to create RSA key\n");
 277                 r = -EINVAL;
 278                 goto out;
 279         }
 280
 281         if (SHA1(db, dblen, hash) != hash) {
 282                 fprintf(stderr, "Failed to calculate SHA sum\n");
 283                 r = -EINVAL;
 284                 goto out;
 285         }
 286
 287         for (i = 0; i < sizeof(keys)/sizeof(keys[0]); i++) {
 288                 rsa->e = &keys[i].e;
 289                 rsa->n = &keys[i].n;
 290
 291                 if (RSA_size(rsa) != siglen)
 292                         continue;
 293
 294                 ok = RSA_verify(NID_sha1, hash, SHA_DIGEST_LENGTH,
 295                                 db + dblen, siglen, rsa) == 1;
 296                 if (ok)
 297                         break;
 298         }
 299
 300         if (!ok) {
 301                 fprintf(stderr, "Database signature wrong\n");
 302                 r = -EINVAL;
 303                 goto out;
 304         }
 305
 306         rsa->e = NULL;
 307         rsa->n = NULL;
 308         RSA_free(rsa);
 309
 310         BN_print_fp(stdout, &keys[0].n);
 311
 312 #endif
 313
 314 #ifdef USE_GCRYPT
 315         /* initialise */
 316         gcry_check_version(NULL);
 317
 318         /* hash the db */
 319         gcry_md_hash_buffer(GCRY_MD_SHA1, hash, db, dblen);
 320
 321         if (gcry_sexp_build(&data, NULL, "(data (flags pkcs1) (hash sha1 %b))",
 322                             20, hash)) {
 323                 fprintf(stderr, "failed to build data expression\n");
 324                 return 2;
 325         }
 326
 327         if (gcry_sexp_build(&signature, NULL, "(sig-val (rsa (s %b)))",
 328                             siglen, db + dblen)) {
 329                 fprintf(stderr, "failed to build signature expression\n");
 330                 return 2;
 331         }
 332
 333         for (i = 0; i < sizeof(keys)/sizeof(keys[0]); i++) {
 334                 if (gcry_mpi_scan(&mpi_e, GCRYMPI_FMT_USG,
 335                                   keys[0].e, keys[0].len_e, NULL) ||
 336                     gcry_mpi_scan(&mpi_n, GCRYMPI_FMT_USG,
 337                                   keys[0].n, keys[0].len_n, NULL)) {
 338                         fprintf(stderr, "failed to convert numbers\n");
 339                         return 2;
 340                 }
 341
 342                 if (gcry_sexp_build(&rsa, NULL,
 343                                     "(public-key (rsa (n %m) (e %m)))",
 344                                     mpi_n, mpi_e)) {
 345                         fprintf(stderr, "failed to build rsa key\n");
 346                         return 2;
 347                 }
 348
 349                 if (!gcry_pk_verify(signature, data, rsa)) {
 350                         ok = 1;
 351                         break;
 352                 }
 353         }
 354
 355         if (!ok) {
 356                 fprintf(stderr, "Database signature wrong\n");
 357                 return 2;
 358         }
 359
 360 #endif
 361
 362         num_countries = ntohl(header->reg_country_num);
 363         countries = get_file_ptr(db, dblen,
 364                                  sizeof(struct regdb_file_reg_country) * num_countries,
 365                                  header->reg_country_ptr);
 366
 367         for (i = 0; i < num_countries; i++) {
 368                 country = countries + i;
 369                 if (memcmp(country->alpha2, alpha2, 2) == 0) {
 370                         found_country = 1;
 371                         break;
 372                 }
 373         }
 374
 375         if (!found_country) {
 376                 fprintf(stderr, "failed to find a country match in regulatory database\n");
 377                 return -1;
 378         }
 379
 380         msg = nlmsg_alloc();
 381         if (!msg) {
 382                 fprintf(stderr, "failed to allocate netlink msg\n");
 383                 return -1;
 384         }
 385
 386         genlmsg_put(msg, 0, 0, genl_family_get_id(nlstate.nl80211), 0,
 387                 0, NL80211_CMD_SET_REG, 0);
 388
 389
 390         rcoll = get_file_ptr(db, dblen, sizeof(*rcoll), country->reg_collection_ptr);
 391         num_rules = ntohl(rcoll->reg_rule_num);
 392         /* re-get pointer with sanity checking for num_rules */
 393         rcoll = get_file_ptr(db, dblen,
 394                              sizeof(*rcoll) + num_rules * sizeof(__be32),
 395                              country->reg_collection_ptr);
 396
 397         NLA_PUT_STRING(msg, NL80211_ATTR_REG_ALPHA2, (char *) country->alpha2);
 398
 399         nl_reg_rules = nla_nest_start(msg, NL80211_ATTR_REG_RULES);
 400         if (!nl_reg_rules) {
 401                 r = -1;
 402                 goto nla_put_failure;
 403         }
 404
 405         for (j = 0; j < num_rules; j++) {
 406                 struct nlattr *nl_reg_rule;
 407                 nl_reg_rule = nla_nest_start(msg, i);
 408                 if (!nl_reg_rule)
 409                         goto nla_put_failure;
 410
 411                 r = put_reg_rule(db, dblen, rcoll->reg_rule_ptrs[j], msg);
 412                 if (r)
 413                         goto nla_put_failure;
 414
 415                 nla_nest_end(msg, nl_reg_rule);
 416         }
 417
 418         nla_nest_end(msg, nl_reg_rules);
 419
 420         cb = nl_cb_alloc(NL_CB_CUSTOM);
 421         if (!cb)
 422                 goto cb_out;
 423
 424         r = nl_send_auto_complete(nlstate.nl_handle, msg);
 425
 426         if (r < 0) {
 427                 fprintf(stderr, "failed to send regulatory request: %d\n", r);
 428                 goto cb_out;
 429         }
 430
 431         nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, reg_handler, NULL);
 432         nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, wait_handler, &finished);
 433         nl_cb_err(cb, NL_CB_CUSTOM, error_handler, NULL);
 434
 435         if (!finished) {
 436                 r = nl_wait_for_ack(nlstate.nl_handle);
 437                 if (r < 0) {
 438                         fprintf(stderr, "failed to set regulatory domain: %d\n", r);
 439                         goto cb_out;
 440                 }
 441         }
 442
 443 cb_out:
 444         nl_cb_put(cb);
 445 nla_put_failure:
 446         nlmsg_free(msg);
 447 out:
 448         nl80211_cleanup(&nlstate);
 449         return r;
 450 }