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>

1 files changed, 117 insertions, 0 deletions

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)