crda.c

/*
 * Central Regulatory Domain Agent for Linux
 *
 * Userspace helper which sends regulatory domains to Linux via nl80211
 */

#include <errno.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <arpa/inet.h>

#include <netlink/genl/genl.h>
#include <netlink/genl/family.h>
#include <netlink/genl/ctrl.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
#include "nl80211.h"

#include "regdb.h"
#include "reglib.h"

struct nl80211_state {
	struct nl_handle *nl_handle;
	struct nl_cache *nl_cache;
	struct genl_family *nl80211;
};

static int nl80211_init(struct nl80211_state *state)
{
	int err;

	state->nl_handle = nl_handle_alloc();
	if (!state->nl_handle) {
		fprintf(stderr, "Failed to allocate netlink handle.\n");
		return -ENOMEM;
	}

	if (genl_connect(state->nl_handle)) {
		fprintf(stderr, "Failed to connect to generic netlink.\n");
		err = -ENOLINK;
		goto out_handle_destroy;
	}

	state->nl_cache = genl_ctrl_alloc_cache(state->nl_handle);
	if (!state->nl_cache) {
		fprintf(stderr, "Failed to allocate generic netlink cache.\n");
		err = -ENOMEM;
		goto out_handle_destroy;
	}

	state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
	if (!state->nl80211) {
		fprintf(stderr, "nl80211 not found.\n");
		err = -ENOENT;
		goto out_cache_free;
	}

	return 0;

 out_cache_free:
	nl_cache_free(state->nl_cache);
 out_handle_destroy:
	nl_handle_destroy(state->nl_handle);
	return err;
}

static void nl80211_cleanup(struct nl80211_state *state)
{
	genl_family_put(state->nl80211);
	nl_cache_free(state->nl_cache);
	nl_handle_destroy(state->nl_handle);
}

static int reg_handler(struct nl_msg __attribute__((unused)) *msg,
			void __attribute__((unused)) *arg)
{
	return NL_SKIP;
}

static int wait_handler(struct nl_msg __attribute__((unused)) *msg, void *arg)
{
	int *finished = arg;
	*finished = 1;
	return NL_STOP;
}

static int error_handler(struct sockaddr_nl __attribute__((unused)) *nla,
			    struct nlmsgerr *err,
			    void __attribute__((unused)) *arg)
{
	fprintf(stderr, "nl80211 error %d\n", err->error);
	exit(err->error);
}

static int put_reg_rule(__u8 *db, int dblen, __be32 ruleptr, struct nl_msg *msg)
{
	struct regdb_file_reg_rule *rule;
	struct regdb_file_freq_range *freq;
	struct regdb_file_power_rule *power;

	rule  = crda_get_file_ptr(db, dblen, sizeof(*rule), ruleptr);
	freq  = crda_get_file_ptr(db, dblen, sizeof(*freq), rule->freq_range_ptr);
	power = crda_get_file_ptr(db, dblen, sizeof(*power), rule->power_rule_ptr);

	NLA_PUT_U32(msg, NL80211_ATTR_REG_RULE_FLAGS,		ntohl(rule->flags));
	NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_START,		ntohl(freq->start_freq));
	NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_END,		ntohl(freq->end_freq));
	NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_MAX_BW,	ntohl(freq->max_bandwidth));
	NLA_PUT_U32(msg, NL80211_ATTR_POWER_RULE_MAX_ANT_GAIN,	ntohl(power->max_antenna_gain));
	NLA_PUT_U32(msg, NL80211_ATTR_POWER_RULE_MAX_EIRP,	ntohl(power->max_eirp));

	return 0;

nla_put_failure:
	return -1;
}

int main(int argc, char **argv)
{
	int fd;
	struct stat stat;
	__u8 *db;
	struct regdb_file_header *header;
	struct regdb_file_reg_country *countries;
	int dblen, siglen, num_countries, i, j, r;
	char alpha2[2];
	char *env_country;
	struct nl80211_state nlstate;
	struct nl_cb *cb = NULL;
	struct nl_msg *msg;
	int found_country = 0;
	int finished = 0;

	struct regdb_file_reg_rules_collection *rcoll;
	struct regdb_file_reg_country *country;
	struct nlattr *nl_reg_rules;
	int num_rules;

	const char regdb[] = "/usr/lib/crda/regulatory.bin";

	if (argc != 1) {
		fprintf(stderr, "Usage: %s\n", argv[0]);
		return -EINVAL;
	}

	env_country = getenv("COUNTRY");
	if (!env_country) {
		fprintf(stderr, "COUNTRY environment variable not set.\n");
		return -EINVAL;
	}

	if (!is_valid_regdom(env_country)) {
		fprintf(stderr, "COUNTRY environment variable must be an "
			"ISO ISO 3166-1-alpha-2 (uppercase) or 00\n");
		return -EINVAL;
	}

	memcpy(alpha2, env_country, 2);

	fd = open(regdb, O_RDONLY);
	if (fd < 0) {
		perror("failed to open db file");
		return -ENOENT;
	}

	if (fstat(fd, &stat)) {
		perror("failed to fstat db file");
		return -EIO;
	}

	dblen = stat.st_size;

	db = mmap(NULL, dblen, PROT_READ, MAP_PRIVATE, fd, 0);
	if (db == MAP_FAILED) {
		perror("failed to mmap db file");
		return -EIO;
	}

	/* db file starts with a struct regdb_file_header */
	header = crda_get_file_ptr(db, dblen, sizeof(*header), 0);

	if (ntohl(header->magic) != REGDB_MAGIC) {
		fprintf(stderr, "Invalid database magic\n");
		return -EINVAL;
	}

	if (ntohl(header->version) != REGDB_VERSION) {
		fprintf(stderr, "Invalid database version\n");
		return -EINVAL;
	}

	siglen = ntohl(header->signature_length);
	/* adjust dblen so later sanity checks don't run into the signature */
	dblen -= siglen;

	if (dblen <= (int)sizeof(*header)) {
		fprintf(stderr, "Invalid signature length %d\n", siglen);
		return -EINVAL;
	}

	/* verify signature */
	if (!crda_verify_db_signature(db, dblen, siglen))
		return -EINVAL;

	num_countries = ntohl(header->reg_country_num);
	countries = crda_get_file_ptr(db, dblen,
			sizeof(struct regdb_file_reg_country) * num_countries,
			header->reg_country_ptr);

	for (i = 0; i < num_countries; i++) {
		country = countries + i;
		if (memcmp(country->alpha2, alpha2, 2) == 0) {
			found_country = 1;
			break;
		}
	}

	if (!found_country) {
		fprintf(stderr, "No country match in regulatory database.\n");
		return -1;
	}

	r = nl80211_init(&nlstate);
	if (r)
		return -EIO;

	msg = nlmsg_alloc();
	if (!msg) {
		fprintf(stderr, "Failed to allocate netlink message.\n");
		r = -1;
		goto out;
	}

	genlmsg_put(msg, 0, 0, genl_family_get_id(nlstate.nl80211), 0,
		0, NL80211_CMD_SET_REG, 0);

	rcoll = crda_get_file_ptr(db, dblen, sizeof(*rcoll),
				country->reg_collection_ptr);
	num_rules = ntohl(rcoll->reg_rule_num);
	/* re-get pointer with sanity checking for num_rules */
	rcoll = crda_get_file_ptr(db, dblen,
				sizeof(*rcoll) + num_rules * sizeof(__be32),
				country->reg_collection_ptr);

	NLA_PUT_STRING(msg, NL80211_ATTR_REG_ALPHA2, (char *) country->alpha2);

	nl_reg_rules = nla_nest_start(msg, NL80211_ATTR_REG_RULES);
	if (!nl_reg_rules) {
		r = -1;
		goto nla_put_failure;
	}

	for (j = 0; j < num_rules; j++) {
		struct nlattr *nl_reg_rule;
		nl_reg_rule = nla_nest_start(msg, i);
		if (!nl_reg_rule)
			goto nla_put_failure;

		r = put_reg_rule(db, dblen, rcoll->reg_rule_ptrs[j], msg);
		if (r)
			goto nla_put_failure;

		nla_nest_end(msg, nl_reg_rule);
	}

	nla_nest_end(msg, nl_reg_rules);

	cb = nl_cb_alloc(NL_CB_CUSTOM);
	if (!cb)
		goto cb_out;

	r = nl_send_auto_complete(nlstate.nl_handle, msg);

	if (r < 0) {
		fprintf(stderr, "Failed to send regulatory request: %d\n", r);
		goto cb_out;
	}

	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, reg_handler, NULL);
	nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, wait_handler, &finished);
	nl_cb_err(cb, NL_CB_CUSTOM, error_handler, NULL);

	if (!finished) {
		r = nl_wait_for_ack(nlstate.nl_handle);
		if (r < 0) {
			fprintf(stderr, "Failed to set regulatory domain: "
				"%d\n", r);
			goto cb_out;
		}
	}

cb_out:
	nl_cb_put(cb);
nla_put_failure:
	nlmsg_free(msg);
out:
	nl80211_cleanup(&nlstate);
	return r;
}