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>

5 files changed, 285 insertions, 15 deletions

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index a46ac6c9b365..bf1737fc9a7e 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -41,44 +41,57 @@ rdev_fixed_channel(struct cfg80211_registered_device *rdev,
         return result;
 }
 
-int rdev_set_freq(struct cfg80211_registered_device *rdev,
-                  struct wireless_dev *for_wdev,
+struct ieee80211_channel *
+rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
                   int freq, enum nl80211_channel_type channel_type)
 {
         struct ieee80211_channel *chan;
         struct ieee80211_sta_ht_cap *ht_cap;
-        int result;
-
-        if (rdev_fixed_channel(rdev, for_wdev))
-                return -EBUSY;
-
-        if (!rdev->ops->set_channel)
-                return -EOPNOTSUPP;
 
         chan = ieee80211_get_channel(&rdev->wiphy, freq);
 
         /* Primary channel not allowed */
         if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)
-                return -EINVAL;
+                return NULL;
 
         if (channel_type == NL80211_CHAN_HT40MINUS &&
             chan->flags & IEEE80211_CHAN_NO_HT40MINUS)
-                return -EINVAL;
+                return NULL;
         else if (channel_type == NL80211_CHAN_HT40PLUS &&
                  chan->flags & IEEE80211_CHAN_NO_HT40PLUS)
-                return -EINVAL;
+                return NULL;
 
         ht_cap = &rdev->wiphy.bands[chan->band]->ht_cap;
 
         if (channel_type != NL80211_CHAN_NO_HT) {
                 if (!ht_cap->ht_supported)
-                        return -EINVAL;
+                        return NULL;
 
                 if (!(ht_cap->cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) ||
                     ht_cap->cap & IEEE80211_HT_CAP_40MHZ_INTOLERANT)
-                        return -EINVAL;
+                        return NULL;
         }
 
+        return chan;
+}
+
+int rdev_set_freq(struct cfg80211_registered_device *rdev,
+                  struct wireless_dev *for_wdev,
+                  int freq, enum nl80211_channel_type channel_type)
+{
+        struct ieee80211_channel *chan;
+        int result;
+
+        if (rdev_fixed_channel(rdev, for_wdev))
+                return -EBUSY;
+
+        if (!rdev->ops->set_channel)
+                return -EOPNOTSUPP;
+
+        chan = rdev_freq_to_chan(rdev, freq, channel_type);
+        if (!chan)
+                return -EINVAL;
+
         result = rdev->ops->set_channel(&rdev->wiphy, chan, channel_type);
         if (result)
                 return result;
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 35b712127143..30ec95f05b52 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -374,6 +374,9 @@ void cfg80211_process_rdev_events(struct cfg80211_registered_device *rdev);
 struct ieee80211_channel *
 rdev_fixed_channel(struct cfg80211_registered_device *rdev,
                    struct wireless_dev *for_wdev);
+struct ieee80211_channel *
+rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
+                  int freq, enum nl80211_channel_type channel_type);
 int rdev_set_freq(struct cfg80211_registered_device *rdev,
                   struct wireless_dev *for_wdev,
                   int freq, enum nl80211_channel_type channel_type);
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index acaeaa784d68..11f6469b3f98 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -680,3 +680,30 @@ void cfg80211_mlme_down(struct cfg80211_registered_device *rdev,
                 }
         }
 }
+
+void cfg80211_ready_on_channel(struct net_device *dev, u64 cookie,
+                               struct ieee80211_channel *chan,
+                               enum nl80211_channel_type channel_type,
+                               unsigned int duration, gfp_t gfp)
+{
+        struct wiphy *wiphy = dev->ieee80211_ptr->wiphy;
+        struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+
+        nl80211_send_remain_on_channel(rdev, dev, cookie, chan, channel_type,
+                                       duration, gfp);
+}
+EXPORT_SYMBOL(cfg80211_ready_on_channel);
+
+void cfg80211_remain_on_channel_expired(struct net_device *dev,
+                                        u64 cookie,
+                                        struct ieee80211_channel *chan,
+                                        enum nl80211_channel_type channel_type,
+                                        gfp_t gfp)
+{
+        struct wiphy *wiphy = dev->ieee80211_ptr->wiphy;
+        struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+
+        nl80211_send_remain_on_channel_cancel(rdev, dev, cookie, chan,
+                                              channel_type, gfp);
+}
+EXPORT_SYMBOL(cfg80211_remain_on_channel_expired);
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)
diff --git a/net/wireless/nl80211.h b/net/wireless/nl80211.h
index 44cc2a76a1b0..a5e2de419b7a 100644
--- a/net/wireless/nl80211.h
+++ b/net/wireless/nl80211.h
@@ -59,4 +59,15 @@ void nl80211_send_ibss_bssid(struct cfg80211_registered_device *rdev,
                              struct net_device *netdev, const u8 *bssid,
                              gfp_t gfp);
 
+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);
+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);
+
 #endif /* __NET_WIRELESS_NL80211_H */