cfg80211: add remain-on-channel command

Add new commands for requesting the driver to remain awake
on a specified channel for the specified amount of time
(and another command to cancel such an operation). This
can be used to implement userspace-controlled off-channel
operations, like Public Action frame exchange on another
channel than the operation channel.

The off-channel operation should behave similarly to scan,
i.e. the local station (if associated) moves into power
save mode to request the AP to buffer frames for it and
then moves to the other channel to allow the off-channel
operation to be completed. The duration parameter can be
used to request enough time to receive a response from
the target station.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 217 insertions, 1 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 60f854377f90..ff857f10cb85 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -141,6 +141,8 @@ static struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] __read_mostly = {
 	[NL80211_ATTR_4ADDR] = { .type = NLA_U8 },
 	[NL80211_ATTR_PMKID] = { .type = NLA_BINARY,
 				 .len = WLAN_PMKID_LEN },
+	[NL80211_ATTR_DURATION] = { .type = NLA_U32 },
+	[NL80211_ATTR_COOKIE] = { .type = NLA_U64 },
 };
 
 /* policy for the attributes */
@@ -569,6 +571,7 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 	CMD(set_pmksa, SET_PMKSA);
 	CMD(del_pmksa, DEL_PMKSA);
 	CMD(flush_pmksa, FLUSH_PMKSA);
+	CMD(remain_on_channel, REMAIN_ON_CHANNEL);
 	if (dev->wiphy.flags & WIPHY_FLAG_NETNS_OK) {
 		i++;
 		NLA_PUT_U32(msg, i, NL80211_CMD_SET_WIPHY_NETNS);
@@ -4283,6 +4286,143 @@ static int nl80211_flush_pmksa(struct sk_buff *skb, struct genl_info *info)
 
 }
 
+static int nl80211_remain_on_channel(struct sk_buff *skb,
+				     struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev;
+	struct net_device *dev;
+	struct ieee80211_channel *chan;
+	struct sk_buff *msg;
+	void *hdr;
+	u64 cookie;
+	enum nl80211_channel_type channel_type = NL80211_CHAN_NO_HT;
+	u32 freq, duration;
+	int err;
+
+	if (!info->attrs[NL80211_ATTR_WIPHY_FREQ] ||
+	    !info->attrs[NL80211_ATTR_DURATION])
+		return -EINVAL;
+
+	duration = nla_get_u32(info->attrs[NL80211_ATTR_DURATION]);
+
+	/*
+	 * We should be on that channel for at least one jiffie,
+	 * and more than 5 seconds seems excessive.
+	 */
+	if (!duration || !msecs_to_jiffies(duration) || duration > 5000)
+		return -EINVAL;
+
+	rtnl_lock();
+
+	err = get_rdev_dev_by_info_ifindex(info, &rdev, &dev);
+	if (err)
+		goto unlock_rtnl;
+
+	if (!rdev->ops->remain_on_channel) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (!netif_running(dev)) {
+		err = -ENETDOWN;
+		goto out;
+	}
+
+	if (info->attrs[NL80211_ATTR_WIPHY_CHANNEL_TYPE]) {
+		channel_type = nla_get_u32(
+			info->attrs[NL80211_ATTR_WIPHY_CHANNEL_TYPE]);
+		if (channel_type != NL80211_CHAN_NO_HT &&
+		    channel_type != NL80211_CHAN_HT20 &&
+		    channel_type != NL80211_CHAN_HT40PLUS &&
+		    channel_type != NL80211_CHAN_HT40MINUS)
+			err = -EINVAL;
+			goto out;
+	}
+
+	freq = nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]);
+	chan = rdev_freq_to_chan(rdev, freq, channel_type);
+	if (chan == NULL) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
+			     NL80211_CMD_REMAIN_ON_CHANNEL);
+
+	if (IS_ERR(hdr)) {
+		err = PTR_ERR(hdr);
+		goto free_msg;
+	}
+
+	err = rdev->ops->remain_on_channel(&rdev->wiphy, dev, chan,
+					   channel_type, duration, &cookie);
+
+	if (err)
+		goto free_msg;
+
+	NLA_PUT_U64(msg, NL80211_ATTR_COOKIE, cookie);
+
+	genlmsg_end(msg, hdr);
+	err = genlmsg_reply(msg, info);
+	goto out;
+
+ nla_put_failure:
+	err = -ENOBUFS;
+ free_msg:
+	nlmsg_free(msg);
+ out:
+	cfg80211_unlock_rdev(rdev);
+	dev_put(dev);
+ unlock_rtnl:
+	rtnl_unlock();
+	return err;
+}
+
+static int nl80211_cancel_remain_on_channel(struct sk_buff *skb,
+					    struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev;
+	struct net_device *dev;
+	u64 cookie;
+	int err;
+
+	if (!info->attrs[NL80211_ATTR_COOKIE])
+		return -EINVAL;
+
+	rtnl_lock();
+
+	err = get_rdev_dev_by_info_ifindex(info, &rdev, &dev);
+	if (err)
+		goto unlock_rtnl;
+
+	if (!rdev->ops->cancel_remain_on_channel) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (!netif_running(dev)) {
+		err = -ENETDOWN;
+		goto out;
+	}
+
+	cookie = nla_get_u64(info->attrs[NL80211_ATTR_COOKIE]);
+
+	err = rdev->ops->cancel_remain_on_channel(&rdev->wiphy, dev, cookie);
+
+ out:
+	cfg80211_unlock_rdev(rdev);
+	dev_put(dev);
+ unlock_rtnl:
+	rtnl_unlock();
+	return err;
+}
+
 static struct genl_ops nl80211_ops[] = {
 	{
 		.cmd = NL80211_CMD_GET_WIPHY,
@@ -4545,8 +4685,20 @@ static struct genl_ops nl80211_ops[] = {
 		.policy = nl80211_policy,
 		.flags = GENL_ADMIN_PERM,
 	},
-
+	{
+		.cmd = NL80211_CMD_REMAIN_ON_CHANNEL,
+		.doit = nl80211_remain_on_channel,
+		.policy = nl80211_policy,
+		.flags = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd = NL80211_CMD_CANCEL_REMAIN_ON_CHANNEL,
+		.doit = nl80211_cancel_remain_on_channel,
+		.policy = nl80211_policy,
+		.flags = GENL_ADMIN_PERM,
+	},
 };
+
 static struct genl_multicast_group nl80211_mlme_mcgrp = {
 	.name = "mlme",
 };
@@ -5134,6 +5286,70 @@ nla_put_failure:
 	nlmsg_free(msg);
 }
 
+static void nl80211_send_remain_on_chan_event(
+	int cmd, struct cfg80211_registered_device *rdev,
+	struct net_device *netdev, u64 cookie,
+	struct ieee80211_channel *chan,
+	enum nl80211_channel_type channel_type,
+	unsigned int duration, gfp_t gfp)
+{
+	struct sk_buff *msg;
+	void *hdr;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, cmd);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx);
+	NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, netdev->ifindex);
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_FREQ, chan->center_freq);
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_CHANNEL_TYPE, channel_type);
+	NLA_PUT_U64(msg, NL80211_ATTR_COOKIE, cookie);
+
+	if (cmd == NL80211_CMD_REMAIN_ON_CHANNEL)
+		NLA_PUT_U32(msg, NL80211_ATTR_DURATION, duration);
+
+	if (genlmsg_end(msg, hdr) < 0) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	genlmsg_multicast_netns(wiphy_net(&rdev->wiphy), msg, 0,
+				nl80211_mlme_mcgrp.id, gfp);
+	return;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	nlmsg_free(msg);
+}
+
+void nl80211_send_remain_on_channel(struct cfg80211_registered_device *rdev,
+				    struct net_device *netdev, u64 cookie,
+				    struct ieee80211_channel *chan,
+				    enum nl80211_channel_type channel_type,
+				    unsigned int duration, gfp_t gfp)
+{
+	nl80211_send_remain_on_chan_event(NL80211_CMD_REMAIN_ON_CHANNEL,
+					  rdev, netdev, cookie, chan,
+					  channel_type, duration, gfp);
+}
+
+void nl80211_send_remain_on_channel_cancel(
+	struct cfg80211_registered_device *rdev, struct net_device *netdev,
+	u64 cookie, struct ieee80211_channel *chan,
+	enum nl80211_channel_type channel_type, gfp_t gfp)
+{
+	nl80211_send_remain_on_chan_event(NL80211_CMD_CANCEL_REMAIN_ON_CHANNEL,
+					  rdev, netdev, cookie, chan,
+					  channel_type, 0, gfp);
+}
+
 /* initialisation/exit functions */
 
 int nl80211_init(void)