[PATCH] {nl,mac}80211: allow 4addr AP operation on crypto controlled devices

[Manikanta Pubbisetty <mpubbise@xxxxxxxxxxxxxx>]

As per the current design, for sw crypto controlled devices, it is
the device which has to advertise the support for AP/VLAN iftype
based on it's capability to tranmsit packets encrypted in software
(In VLAN functionality, group traffic generated for a specific
VLAN group is always encrypted in software). Commit db3bdcb9c3ff
("mac80211: allow AP_VLAN operation on crypto controlled devices")
has introduced this change.

Since 4addr AP operation also uses AP/VLAN iftype, this conditional
way of advertising AP/VLAN support has broken 4addr AP mode operation on
crypto controlled devices which do not support VLAN functionality.

For example:
In the case of ath10k driver, not all firmwares have support for VLAN
functionality but all can support 4addr AP operation. Because AP/VLAN
support is not advertised for these devices, 4addr AP operations are
also blocked.

Fix this by allowing 4addr opertion on devices which do not advertise
AP/VLAN iftype but which can support 4addr operation (the desicion is
taken based on the wiphy flag WIPHY_FLAG_4ADDR_AP).

Fixes: Commit db3bdcb9c3ff ("mac80211: allow AP_VLAN operation on
crypto controlled devices")
Signed-off-by: Manikanta Pubbisetty <mpubbise@xxxxxxxxxxxxxx>
---
 include/net/cfg80211.h |  3 ++-
 net/mac80211/util.c    |  4 +++-
 net/wireless/core.c    |  9 +++++++--
 net/wireless/nl80211.c | 10 ++++++++--
 4 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index ede7fcd..666e5a3 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -3708,7 +3708,8 @@ struct cfg80211_ops {
  *	on wiphy_new(), but can be changed by the driver if it has a good
  *	reason to override the default
  * @WIPHY_FLAG_4ADDR_AP: supports 4addr mode even on AP (with a single station
- *	on a VLAN interface)
+ *	on a VLAN interface). This flag also serves an extra purpose of
+ *	supporting 4ADDR AP mode on devices which do not support AP/VLAN iftype.
  * @WIPHY_FLAG_4ADDR_STATION: supports 4addr mode even as a station
  * @WIPHY_FLAG_CONTROL_PORT_PROTOCOL: This device supports setting the
  *	control port protocol ethertype. The device also honours the
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index bec4243..6a8571d 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -3643,7 +3643,9 @@ int ieee80211_check_combinations(struct ieee80211_sub_if_data *sdata,
 	}
 
 	/* Always allow software iftypes */
-	if (local->hw.wiphy->software_iftypes & BIT(iftype)) {
+	if (local->hw.wiphy->software_iftypes & BIT(iftype) ||
+	    (iftype == NL80211_IFTYPE_AP_VLAN &&
+	     local->hw.wiphy->flags & WIPHY_FLAG_4ADDR_AP)) {
 		if (radar_detect)
 			return -EINVAL;
 		return 0;
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 623dfe5..93085fb 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1394,8 +1394,13 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		}
 		break;
 	case NETDEV_PRE_UP:
-		if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype)))
-			return notifier_from_errno(-EOPNOTSUPP);
+		if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype))) {
+			if (!(wdev->iftype == NL80211_IFTYPE_AP_VLAN &&
+			      rdev->wiphy.flags & WIPHY_FLAG_4ADDR_AP &&
+			      wdev->use_4addr))
+				return notifier_from_errno(-EOPNOTSUPP);
+		}
+
 		if (rfkill_blocked(rdev->rfkill))
 			return notifier_from_errno(-ERFKILL);
 		break;
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index e20329b..2863d9a 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3383,8 +3383,7 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 	if (info->attrs[NL80211_ATTR_IFTYPE])
 		type = nla_get_u32(info->attrs[NL80211_ATTR_IFTYPE]);
 
-	if (!rdev->ops->add_virtual_intf ||
-	    !(rdev->wiphy.interface_modes & (1 << type)))
+	if (!rdev->ops->add_virtual_intf)
 		return -EOPNOTSUPP;
 
 	if ((type == NL80211_IFTYPE_P2P_DEVICE || type == NL80211_IFTYPE_NAN ||
@@ -3403,6 +3402,13 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 			return err;
 	}
 
+	if (!(rdev->wiphy.interface_modes & (1 << type))) {
+		if (!(type == NL80211_IFTYPE_AP_VLAN &&
+		      rdev->wiphy.flags & WIPHY_FLAG_4ADDR_AP &&
+		      params.use_4addr))
+			return -EOPNOTSUPP;
+	}
+
 	err = nl80211_parse_mon_options(rdev, type, info, &params);
 	if (err < 0)
 		return err;
-- 
2.7.4