cfg80211: add get reg command

This lets userspace request to get the currently set
regulatory domain.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/nl80211.h

@@ -113,6 +113,8 @@
  * @NL80211_CMD_SET_BSS: Set BSS attributes for BSS identified by
  *	%NL80211_ATTR_IFINDEX.
  *
+ * @NL80211_CMD_GET_REG: ask the wireless core to send us its currently set
+ * 	regulatory domain.
  * @NL80211_CMD_SET_REG: Set current regulatory domain. CRDA sends this command
  *	after being queried by the kernel. CRDA replies by sending a regulatory
  *	domain structure which consists of %NL80211_ATTR_REG_ALPHA set to our
@@ -188,6 +190,8 @@ enum nl80211_commands {
 
 	NL80211_CMD_SET_MGMT_EXTRA_IE,
 
+	NL80211_CMD_GET_REG,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */

net/wireless/nl80211.c

@@ -2093,6 +2093,81 @@ static int nl80211_set_mesh_params(struct sk_buff *skb, struct genl_info *info)
 
 #undef FILL_IN_MESH_PARAM_IF_SET
 
+static int nl80211_get_reg(struct sk_buff *skb, struct genl_info *info)
+{
+	struct sk_buff *msg;
+	void *hdr = NULL;
+	struct nlattr *nl_reg_rules;
+	unsigned int i;
+	int err = -EINVAL;
+
+	mutex_lock(&cfg80211_drv_mutex);
+
+	if (!cfg80211_regdomain)
+		goto out;
+
+	msg = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!msg) {
+		err = -ENOBUFS;
+		goto out;
+	}
+
+	hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
+			     NL80211_CMD_GET_REG);
+	if (!hdr)
+		goto nla_put_failure;
+
+	NLA_PUT_STRING(msg, NL80211_ATTR_REG_ALPHA2,
+		cfg80211_regdomain->alpha2);
+
+	nl_reg_rules = nla_nest_start(msg, NL80211_ATTR_REG_RULES);
+	if (!nl_reg_rules)
+		goto nla_put_failure;
+
+	for (i = 0; i < cfg80211_regdomain->n_reg_rules; i++) {
+		struct nlattr *nl_reg_rule;
+		const struct ieee80211_reg_rule *reg_rule;
+		const struct ieee80211_freq_range *freq_range;
+		const struct ieee80211_power_rule *power_rule;
+
+		reg_rule = &cfg80211_regdomain->reg_rules[i];
+		freq_range = &reg_rule->freq_range;
+		power_rule = &reg_rule->power_rule;
+
+		nl_reg_rule = nla_nest_start(msg, i);
+		if (!nl_reg_rule)
+			goto nla_put_failure;
+
+		NLA_PUT_U32(msg, NL80211_ATTR_REG_RULE_FLAGS,
+			reg_rule->flags);
+		NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_START,
+			freq_range->start_freq_khz);
+		NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_END,
+			freq_range->end_freq_khz);
+		NLA_PUT_U32(msg, NL80211_ATTR_FREQ_RANGE_MAX_BW,
+			freq_range->max_bandwidth_khz);
+		NLA_PUT_U32(msg, NL80211_ATTR_POWER_RULE_MAX_ANT_GAIN,
+			power_rule->max_antenna_gain);
+		NLA_PUT_U32(msg, NL80211_ATTR_POWER_RULE_MAX_EIRP,
+			power_rule->max_eirp);
+
+		nla_nest_end(msg, nl_reg_rule);
+	}
+
+	nla_nest_end(msg, nl_reg_rules);
+
+	genlmsg_end(msg, hdr);
+	err = genlmsg_unicast(msg, info->snd_pid);
+	goto out;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	err = -EMSGSIZE;
+out:
+	mutex_unlock(&cfg80211_drv_mutex);
+	return err;
+}
+
 static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr *tb[NL80211_REG_RULE_ATTR_MAX + 1];
@@ -2332,6 +2407,12 @@ static struct genl_ops nl80211_ops[] = {
 		.policy = nl80211_policy,
 		.flags = GENL_ADMIN_PERM,
 	},
+	{
+		.cmd = NL80211_CMD_GET_REG,
+		.doit = nl80211_get_reg,
+		.policy = nl80211_policy,
+		/* can be retrieved by unprivileged users */
+	},
 	{
 		.cmd = NL80211_CMD_SET_REG,
 		.doit = nl80211_set_reg,

net/wireless/reg.c

@@ -57,7 +57,7 @@ static u32 supported_bandwidths[] = {
 /* Central wireless core regulatory domains, we only need two,
  * the current one and a world regulatory domain in case we have no
  * information to give us an alpha2 */
-static const struct ieee80211_regdomain *cfg80211_regdomain;
+const struct ieee80211_regdomain *cfg80211_regdomain;
 
 /* We use this as a place for the rd structure built from the
  * last parsed country IE to rest until CRDA gets back to us with

net/wireless/reg.h

@@ -1,6 +1,8 @@
 #ifndef __NET_WIRELESS_REG_H
 #define __NET_WIRELESS_REG_H
 
+extern const struct ieee80211_regdomain *cfg80211_regdomain;
+
 bool is_world_regdom(const char *alpha2);
 bool reg_is_valid_request(const char *alpha2);