cfg80211: introduce critical protocol indication from user-space

Some protocols need a more reliable connection to complete
successful in reasonable time. This patch adds a user-space
API to indicate the wireless driver that a critical protocol
is about to commence and when it is done, using nl80211 primitives
NL80211_CMD_CRIT_PROTOCOL_START and NL80211_CRIT_PROTOCOL_STOP.

There can be only on critical protocol session started per
registered cfg80211 device.

The driver can support this by implementing the cfg80211 callbacks
.crit_proto_start() and .crit_proto_stop(). Examples of protocols
that can benefit from this are DHCP, EAPOL, APIPA. Exactly how the
link can/should be made more reliable is up to the driver. Things
to consider are avoid scanning, no multi-channel operations, and
alter coexistence schemes.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

5 files changed, 183 insertions, 1 deletions

diff --git a/net/wireless/core.h b/net/wireless/core.h
index 124e5e773fbc..fd35dae547c4 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -88,6 +88,9 @@ struct cfg80211_registered_device {
 
         struct delayed_work dfs_update_channels_wk;
 
+        /* netlink port which started critical protocol (0 means not started) */
+        u32 crit_proto_nlportid;
+
         /* must be last because of the way we do wiphy_priv(),
          * and it should at least be aligned to NETDEV_ALIGN */
         struct wiphy wiphy __aligned(NETDEV_ALIGN);
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 390198bf4b36..0c7b7dd855f6 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -648,6 +648,11 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlportid)
 
         spin_unlock_bh(&wdev->mgmt_registrations_lock);
 
+        if (nlportid && rdev->crit_proto_nlportid == nlportid) {
+                rdev->crit_proto_nlportid = 0;
+                rdev_crit_proto_stop(rdev, wdev);
+        }
+
         if (nlportid == wdev->ap_unexpected_nlportid)
                 wdev->ap_unexpected_nlportid = 0;
 }
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 3abcbbada6d4..afa283841e8c 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1424,6 +1424,10 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *dev,
                 }
                 CMD(start_p2p_device, START_P2P_DEVICE);
                 CMD(set_mcast_rate, SET_MCAST_RATE);
+                if (split) {
+                        CMD(crit_proto_start, CRIT_PROTOCOL_START);
+                        CMD(crit_proto_stop, CRIT_PROTOCOL_STOP);
+                }
 
 #ifdef CONFIG_NL80211_TESTMODE
                 CMD(testmode_cmd, TESTMODE);
@@ -8216,6 +8220,64 @@ static int nl80211_update_ft_ies(struct sk_buff *skb, struct genl_info *info)
         return rdev_update_ft_ies(rdev, dev, &ft_params);
 }
 
+static int nl80211_crit_protocol_start(struct sk_buff *skb,
+                                       struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev = info->user_ptr[0];
+        struct wireless_dev *wdev = info->user_ptr[1];
+        enum nl80211_crit_proto_id proto = NL80211_CRIT_PROTO_UNSPEC;
+        u16 duration;
+        int ret;
+
+        if (!rdev->ops->crit_proto_start)
+                return -EOPNOTSUPP;
+
+        if (WARN_ON(!rdev->ops->crit_proto_stop))
+                return -EINVAL;
+
+        if (rdev->crit_proto_nlportid)
+                return -EBUSY;
+
+        /* determine protocol if provided */
+        if (info->attrs[NL80211_ATTR_CRIT_PROT_ID])
+                proto = nla_get_u16(info->attrs[NL80211_ATTR_CRIT_PROT_ID]);
+
+        if (proto >= NUM_NL80211_CRIT_PROTO)
+                return -EINVAL;
+
+        /* timeout must be provided */
+        if (!info->attrs[NL80211_ATTR_MAX_CRIT_PROT_DURATION])
+                return -EINVAL;
+
+        duration =
+                nla_get_u16(info->attrs[NL80211_ATTR_MAX_CRIT_PROT_DURATION]);
+
+        if (duration > NL80211_CRIT_PROTO_MAX_DURATION)
+                return -ERANGE;
+
+        ret = rdev_crit_proto_start(rdev, wdev, proto, duration);
+        if (!ret)
+                rdev->crit_proto_nlportid = info->snd_portid;
+
+        return ret;
+}
+
+static int nl80211_crit_protocol_stop(struct sk_buff *skb,
+                                      struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev = info->user_ptr[0];
+        struct wireless_dev *wdev = info->user_ptr[1];
+
+        if (!rdev->ops->crit_proto_stop)
+                return -EOPNOTSUPP;
+
+        if (rdev->crit_proto_nlportid) {
+                rdev->crit_proto_nlportid = 0;
+                rdev_crit_proto_stop(rdev, wdev);
+        }
+        return 0;
+}
+
 #define NL80211_FLAG_NEED_WIPHY         0x01
 #define NL80211_FLAG_NEED_NETDEV        0x02
 #define NL80211_FLAG_NEED_RTNL          0x04
@@ -8905,6 +8967,22 @@ static struct genl_ops nl80211_ops[] = {
                 .internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
                                   NL80211_FLAG_NEED_RTNL,
         },
+        {
+                .cmd = NL80211_CMD_CRIT_PROTOCOL_START,
+                .doit = nl80211_crit_protocol_start,
+                .policy = nl80211_policy,
+                .flags = GENL_ADMIN_PERM,
+                .internal_flags = NL80211_FLAG_NEED_WDEV_UP |
+                                  NL80211_FLAG_NEED_RTNL,
+        },
+        {
+                .cmd = NL80211_CMD_CRIT_PROTOCOL_STOP,
+                .doit = nl80211_crit_protocol_stop,
+                .policy = nl80211_policy,
+                .flags = GENL_ADMIN_PERM,
+                .internal_flags = NL80211_FLAG_NEED_WDEV_UP |
+                                  NL80211_FLAG_NEED_RTNL,
+        }
 };
 
 static struct genl_multicast_group nl80211_mlme_mcgrp = {
@@ -10650,6 +10728,45 @@ void cfg80211_ft_event(struct net_device *netdev,
 }
 EXPORT_SYMBOL(cfg80211_ft_event);
 
+void cfg80211_crit_proto_stopped(struct wireless_dev *wdev, gfp_t gfp)
+{
+        struct cfg80211_registered_device *rdev;
+        struct sk_buff *msg;
+        void *hdr;
+        u32 nlportid;
+
+        rdev = wiphy_to_dev(wdev->wiphy);
+        if (!rdev->crit_proto_nlportid)
+                return;
+
+        nlportid = rdev->crit_proto_nlportid;
+        rdev->crit_proto_nlportid = 0;
+
+        msg = nlmsg_new(NLMSG_DEFAULT_SIZE, gfp);
+        if (!msg)
+                return;
+
+        hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_CRIT_PROTOCOL_STOP);
+        if (!hdr)
+                goto nla_put_failure;
+
+        if (nla_put_u32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx) ||
+            nla_put_u64(msg, NL80211_ATTR_WDEV, wdev_id(wdev)))
+                goto nla_put_failure;
+
+        genlmsg_end(msg, hdr);
+
+        genlmsg_unicast(wiphy_net(&rdev->wiphy), msg, nlportid);
+        return;
+
+ nla_put_failure:
+        if (hdr)
+                genlmsg_cancel(msg, hdr);
+        nlmsg_free(msg);
+
+}
+EXPORT_SYMBOL(cfg80211_crit_proto_stopped);
+
 /* initialisation/exit functions */
 
 int nl80211_init(void)
diff --git a/net/wireless/rdev-ops.h b/net/wireless/rdev-ops.h
index d77e1c1d3a0e..9f15f0ac824d 100644
--- a/net/wireless/rdev-ops.h
+++ b/net/wireless/rdev-ops.h
@@ -875,7 +875,7 @@ static inline void rdev_stop_p2p_device(struct cfg80211_registered_device *rdev,
         trace_rdev_stop_p2p_device(&rdev->wiphy, wdev);
         rdev->ops->stop_p2p_device(&rdev->wiphy, wdev);
         trace_rdev_return_void(&rdev->wiphy);
-}                                       
+}
 
 static inline int rdev_set_mac_acl(struct cfg80211_registered_device *rdev,
                                    struct net_device *dev,
@@ -901,4 +901,26 @@ static inline int rdev_update_ft_ies(struct cfg80211_registered_device *rdev,
         return ret;
 }
 
+static inline int rdev_crit_proto_start(struct cfg80211_registered_device *rdev,
+                                        struct wireless_dev *wdev,
+                                        enum nl80211_crit_proto_id protocol,
+                                        u16 duration)
+{
+        int ret;
+
+        trace_rdev_crit_proto_start(&rdev->wiphy, wdev, protocol, duration);
+        ret = rdev->ops->crit_proto_start(&rdev->wiphy, wdev,
+                                          protocol, duration);
+        trace_rdev_return_int(&rdev->wiphy, ret);
+        return ret;
+}
+
+static inline void rdev_crit_proto_stop(struct cfg80211_registered_device *rdev,
+                                       struct wireless_dev *wdev)
+{
+        trace_rdev_crit_proto_stop(&rdev->wiphy, wdev);
+        rdev->ops->crit_proto_stop(&rdev->wiphy, wdev);
+        trace_rdev_return_void(&rdev->wiphy);
+}
+
 #endif /* __CFG80211_RDEV_OPS */
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 3c2033b8f596..ecd4fcec3c94 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -1806,6 +1806,41 @@ TRACE_EVENT(rdev_update_ft_ies,
                   WIPHY_PR_ARG, NETDEV_PR_ARG, __entry->md)
 );
 
+TRACE_EVENT(rdev_crit_proto_start,
+        TP_PROTO(struct wiphy *wiphy, struct wireless_dev *wdev,
+                 enum nl80211_crit_proto_id protocol, u16 duration),
+        TP_ARGS(wiphy, wdev, protocol, duration),
+        TP_STRUCT__entry(
+                WIPHY_ENTRY
+                WDEV_ENTRY
+                __field(u16, proto)
+                __field(u16, duration)
+        ),
+        TP_fast_assign(
+                WIPHY_ASSIGN;
+                WDEV_ASSIGN;
+                __entry->proto = protocol;
+                __entry->duration = duration;
+        ),
+        TP_printk(WIPHY_PR_FMT ", " WDEV_PR_FMT ", proto=%x, duration=%u",
+                  WIPHY_PR_ARG, WDEV_PR_ARG, __entry->proto, __entry->duration)
+);
+
+TRACE_EVENT(rdev_crit_proto_stop,
+        TP_PROTO(struct wiphy *wiphy, struct wireless_dev *wdev),
+        TP_ARGS(wiphy, wdev),
+        TP_STRUCT__entry(
+                WIPHY_ENTRY
+                WDEV_ENTRY
+        ),
+        TP_fast_assign(
+                WIPHY_ASSIGN;
+                WDEV_ASSIGN;
+        ),
+        TP_printk(WIPHY_PR_FMT ", " WDEV_PR_FMT,
+                  WIPHY_PR_ARG, WDEV_PR_ARG)
+);
+
 /*************************************************************
  *           cfg80211 exported functions traces              *
  *************************************************************/