nl80211/cfg80211: extend mgmt-tx API for off-channel

With p2p, it is sometimes necessary to transmit
a frame (typically an action frame) on another
channel than the current channel. Enable this
through the CMD_FRAME API, and allow it to wait
for a response. A new command allows that wait
to be aborted.

However, allow userspace to specify whether or
not it wants to allow off-channel TX, it may
actually want to use the same channel only.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

6 files changed, 91 insertions, 22 deletions

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index d706bf3badc8..5cfa579df476 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -358,11 +358,16 @@
  *      user space application). %NL80211_ATTR_FRAME is used to specify the
  *      frame contents (including header). %NL80211_ATTR_WIPHY_FREQ (and
  *      optionally %NL80211_ATTR_WIPHY_CHANNEL_TYPE) is used to indicate on
- *      which channel the frame is to be transmitted or was received. This
- *      channel has to be the current channel (remain-on-channel or the
- *      operational channel). When called, this operation returns a cookie
- *      (%NL80211_ATTR_COOKIE) that will be included with the TX status event
- *      pertaining to the TX request.
+ *      which channel the frame is to be transmitted or was received. If this
+ *      channel is not the current channel (remain-on-channel or the
+ *      operational channel) the device will switch to the given channel and
+ *      transmit the frame, optionally waiting for a response for the time
+ *      specified using %NL80211_ATTR_DURATION. When called, this operation
+ *      returns a cookie (%NL80211_ATTR_COOKIE) that will be included with the
+ *      TX status event pertaining to the TX request.
+ * @NL80211_CMD_FRAME_WAIT_CANCEL: When an off-channel TX was requested, this
+ *      command may be used with the corresponding cookie to cancel the wait
+ *      time if it is known that it is no longer necessary.
  * @NL80211_CMD_ACTION: Alias for @NL80211_CMD_FRAME for backward compatibility.
  * @NL80211_CMD_FRAME_TX_STATUS: Report TX status of a management frame
  *      transmitted with %NL80211_CMD_FRAME. %NL80211_ATTR_COOKIE identifies
@@ -493,6 +498,8 @@ enum nl80211_commands {
         NL80211_CMD_SET_CHANNEL,
         NL80211_CMD_SET_WDS_PEER,
 
+        NL80211_CMD_FRAME_WAIT_CANCEL,
+
         /* add new commands above here */
 
         /* used to define NL80211_CMD_MAX below */
@@ -828,6 +835,12 @@ enum nl80211_commands {
  *
  * @NL80211_ATTR_MCAST_RATE: Multicast tx rate (in 100 kbps) for IBSS
  *
+ * @NL80211_ATTR_OFFCHANNEL_TX_OK: For management frame TX, the frame may be
+ *      transmitted on another channel when the channel given doesn't match
+ *      the current channel. If the current channel doesn't match and this
+ *      flag isn't set, the frame will be rejected. This is also used as an
+ *      nl80211 capability flag.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -1002,6 +1015,8 @@ enum nl80211_attrs {
 
         NL80211_ATTR_MCAST_RATE,
 
+        NL80211_ATTR_OFFCHANNEL_TX_OK,
+
         /* add attributes here, update the policy in nl80211.c */
 
         __NL80211_ATTR_AFTER_LAST,
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 0663945cfa48..49a7c53a48ca 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1134,7 +1134,9 @@ struct cfg80211_pmksa {
  * @cancel_remain_on_channel: Cancel an on-going remain-on-channel operation.
  *      This allows the operation to be terminated prior to timeout based on
  *      the duration value.
- * @mgmt_tx: Transmit a management frame
+ * @mgmt_tx: Transmit a management frame.
+ * @mgmt_tx_cancel_wait: Cancel the wait time from transmitting a management
+ *      frame on another channel
  *
  * @testmode_cmd: run a test mode command
  *
@@ -1291,10 +1293,13 @@ struct cfg80211_ops {
                                             u64 cookie);
 
         int     (*mgmt_tx)(struct wiphy *wiphy, struct net_device *dev,
-                          struct ieee80211_channel *chan,
+                          struct ieee80211_channel *chan, bool offchan,
                           enum nl80211_channel_type channel_type,
-                          bool channel_type_valid,
+                          bool channel_type_valid, unsigned int wait,
                           const u8 *buf, size_t len, u64 *cookie);
+        int     (*mgmt_tx_cancel_wait)(struct wiphy *wiphy,
+                                       struct net_device *dev,
+                                       u64 cookie);
 
         int     (*set_power_mgmt)(struct wiphy *wiphy, struct net_device *dev,
                                   bool enabled, int timeout);
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 0c544074479e..aac2d7de828e 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1552,9 +1552,9 @@ static int ieee80211_cancel_remain_on_channel(struct wiphy *wiphy,
 }
 
 static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct net_device *dev,
-                             struct ieee80211_channel *chan,
+                             struct ieee80211_channel *chan, bool offchan,
                              enum nl80211_channel_type channel_type,
-                             bool channel_type_valid,
+                             bool channel_type_valid, unsigned int wait,
                              const u8 *buf, size_t len, u64 *cookie)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
@@ -1565,6 +1565,9 @@ static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct net_device *dev,
         u32 flags = IEEE80211_TX_INTFL_NL80211_FRAME_TX |
                     IEEE80211_TX_CTL_REQ_TX_STATUS;
 
+        if (offchan)
+                return -EOPNOTSUPP;
+
         /* Check that we are on the requested channel for transmission */
         if (chan != local->tmp_channel &&
             chan != local->oper_channel)
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 6583cca0e2ee..ee80ad8dc655 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -341,9 +341,9 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlpid);
 void cfg80211_mlme_purge_registrations(struct wireless_dev *wdev);
 int cfg80211_mlme_mgmt_tx(struct cfg80211_registered_device *rdev,
                           struct net_device *dev,
-                          struct ieee80211_channel *chan,
+                          struct ieee80211_channel *chan, bool offchan,
                           enum nl80211_channel_type channel_type,
-                          bool channel_type_valid,
+                          bool channel_type_valid, unsigned int wait,
                           const u8 *buf, size_t len, u64 *cookie);
 
 /* SME */
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 6980a0c315b2..d7680f2a4c5b 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -864,9 +864,9 @@ void cfg80211_mlme_purge_registrations(struct wireless_dev *wdev)
 
 int cfg80211_mlme_mgmt_tx(struct cfg80211_registered_device *rdev,
                           struct net_device *dev,
-                          struct ieee80211_channel *chan,
+                          struct ieee80211_channel *chan, bool offchan,
                           enum nl80211_channel_type channel_type,
-                          bool channel_type_valid,
+                          bool channel_type_valid, unsigned int wait,
                           const u8 *buf, size_t len, u64 *cookie)
 {
         struct wireless_dev *wdev = dev->ieee80211_ptr;
@@ -946,8 +946,9 @@ int cfg80211_mlme_mgmt_tx(struct cfg80211_registered_device *rdev,
                 return -EINVAL;
 
         /* Transmit the Action frame as requested by user space */
-        return rdev->ops->mgmt_tx(&rdev->wiphy, dev, chan, channel_type,
-                                  channel_type_valid, buf, len, cookie);
+        return rdev->ops->mgmt_tx(&rdev->wiphy, dev, chan, offchan,
+                                  channel_type, channel_type_valid,
+                                  wait, buf, len, cookie);
 }
 
 bool cfg80211_rx_mgmt(struct net_device *dev, int freq, const u8 *buf,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 67ff7e92cb99..960be4e650f0 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -163,16 +163,13 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
         [NL80211_ATTR_CQM] = { .type = NLA_NESTED, },
         [NL80211_ATTR_LOCAL_STATE_CHANGE] = { .type = NLA_FLAG },
         [NL80211_ATTR_AP_ISOLATE] = { .type = NLA_U8 },
-
         [NL80211_ATTR_WIPHY_TX_POWER_SETTING] = { .type = NLA_U32 },
         [NL80211_ATTR_WIPHY_TX_POWER_LEVEL] = { .type = NLA_U32 },
-
         [NL80211_ATTR_FRAME_TYPE] = { .type = NLA_U16 },
-
         [NL80211_ATTR_WIPHY_ANTENNA_TX] = { .type = NLA_U32 },
         [NL80211_ATTR_WIPHY_ANTENNA_RX] = { .type = NLA_U32 },
-
         [NL80211_ATTR_MCAST_RATE] = { .type = NLA_U32 },
+        [NL80211_ATTR_OFFCHANNEL_TX_OK] = { .type = NLA_FLAG },
 };
 
 /* policy for the key attributes */
@@ -677,6 +674,7 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
         CMD(remain_on_channel, REMAIN_ON_CHANNEL);
         CMD(set_bitrate_mask, SET_TX_BITRATE_MASK);
         CMD(mgmt_tx, FRAME);
+        CMD(mgmt_tx_cancel_wait, FRAME_WAIT_CANCEL);
         if (dev->wiphy.flags & WIPHY_FLAG_NETNS_OK) {
                 i++;
                 NLA_PUT_U32(msg, i, NL80211_CMD_SET_WIPHY_NETNS);
@@ -698,6 +696,10 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 
         nla_nest_end(msg, nl_cmds);
 
+        /* for now at least assume all drivers have it */
+        if (dev->ops->mgmt_tx)
+                NLA_PUT_FLAG(msg, NL80211_ATTR_OFFCHANNEL_TX_OK);
+
         if (mgmt_stypes) {
                 u16 stypes;
                 struct nlattr *nl_ftypes, *nl_ifs;
@@ -4244,6 +4246,8 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
         void *hdr;
         u64 cookie;
         struct sk_buff *msg;
+        unsigned int wait = 0;
+        bool offchan;
 
         if (!info->attrs[NL80211_ATTR_FRAME] ||
             !info->attrs[NL80211_ATTR_WIPHY_FREQ])
@@ -4260,6 +4264,12 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
             dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO)
                 return -EOPNOTSUPP;
 
+        if (info->attrs[NL80211_ATTR_DURATION]) {
+                if (!rdev->ops->mgmt_tx_cancel_wait)
+                        return -EINVAL;
+                wait = nla_get_u32(info->attrs[NL80211_ATTR_DURATION]);
+        }
+
         if (info->attrs[NL80211_ATTR_WIPHY_CHANNEL_TYPE]) {
                 channel_type = nla_get_u32(
                         info->attrs[NL80211_ATTR_WIPHY_CHANNEL_TYPE]);
@@ -4271,6 +4281,8 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
                 channel_type_valid = true;
         }
 
+        offchan = info->attrs[NL80211_ATTR_OFFCHANNEL_TX_OK];
+
         freq = nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]);
         chan = rdev_freq_to_chan(rdev, freq, channel_type);
         if (chan == NULL)
@@ -4287,8 +4299,8 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
                 err = PTR_ERR(hdr);
                 goto free_msg;
         }
-        err = cfg80211_mlme_mgmt_tx(rdev, dev, chan, channel_type,
-                                    channel_type_valid,
+        err = cfg80211_mlme_mgmt_tx(rdev, dev, chan, offchan, channel_type,
+                                    channel_type_valid, wait,
                                     nla_data(info->attrs[NL80211_ATTR_FRAME]),
                                     nla_len(info->attrs[NL80211_ATTR_FRAME]),
                                     &cookie);
@@ -4307,6 +4319,31 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
         return err;
 }
 
+static int nl80211_tx_mgmt_cancel_wait(struct sk_buff *skb, struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev = info->user_ptr[0];
+        struct net_device *dev = info->user_ptr[1];
+        u64 cookie;
+
+        if (!info->attrs[NL80211_ATTR_COOKIE])
+                return -EINVAL;
+
+        if (!rdev->ops->mgmt_tx_cancel_wait)
+                return -EOPNOTSUPP;
+
+        if (dev->ieee80211_ptr->iftype != NL80211_IFTYPE_STATION &&
+            dev->ieee80211_ptr->iftype != NL80211_IFTYPE_ADHOC &&
+            dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_CLIENT &&
+            dev->ieee80211_ptr->iftype != NL80211_IFTYPE_AP &&
+            dev->ieee80211_ptr->iftype != NL80211_IFTYPE_AP_VLAN &&
+            dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO)
+                return -EOPNOTSUPP;
+
+        cookie = nla_get_u64(info->attrs[NL80211_ATTR_COOKIE]);
+
+        return rdev->ops->mgmt_tx_cancel_wait(&rdev->wiphy, dev, cookie);
+}
+
 static int nl80211_set_power_save(struct sk_buff *skb, struct genl_info *info)
 {
         struct cfg80211_registered_device *rdev = info->user_ptr[0];
@@ -4880,6 +4917,14 @@ static struct genl_ops nl80211_ops[] = {
                                   NL80211_FLAG_NEED_RTNL,
         },
         {
+                .cmd = NL80211_CMD_FRAME_WAIT_CANCEL,
+                .doit = nl80211_tx_mgmt_cancel_wait,
+                .policy = nl80211_policy,
+                .flags = GENL_ADMIN_PERM,
+                .internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
+                                  NL80211_FLAG_NEED_RTNL,
+        },
+        {
                 .cmd = NL80211_CMD_SET_POWER_SAVE,
                 .doit = nl80211_set_power_save,
                 .policy = nl80211_policy,