cfg80211: advertise possible interface combinations

Add the ability to advertise interface combinations in nl80211.
This allows the driver to indicate what the combinations are
that it supports. "Combinations" of just a single interface are
implicit, as previously. Note that cfg80211 will enforce that
the restrictions are met, but not for all drivers yet (once all
drivers are updated, we can remove the flag and enforce for all).

When no combinations are actually supported, an empty list will
be exported so that userspace can know if the kernel exported
this info or not (although it isn't clear to me what tools using
the info should do if the kernel didn't export it).

Since some interface types are purely virtual/software and don't
fit the restrictions, those are exposed in a new list of pure SW
types, not subject to restrictions. This mainly exists to handle
AP-VLAN and monitor interfaces in mac80211.

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

1 files changed, 88 insertions, 0 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index e1f1b41f7b1..04afcfb9eaf 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1547,6 +1547,10 @@ struct cfg80211_ops {
  *      hints read the documenation for regulatory_hint_found_beacon()
  * @WIPHY_FLAG_NETNS_OK: if not set, do not allow changing the netns of this
  *      wiphy at all
+ * @WIPHY_FLAG_ENFORCE_COMBINATIONS: Set this flag to enforce interface
+ *      combinations for this device. This flag is used for backward
+ *      compatibility only until all drivers advertise combinations and
+ *      they will always be enforced.
  * @WIPHY_FLAG_PS_ON_BY_DEFAULT: if set to true, powersave will be enabled
  *      by default -- this flag will be set depending on the kernel's default
  *      on wiphy_new(), but can be changed by the driver if it has a good
@@ -1574,6 +1578,81 @@ enum wiphy_flags {
         WIPHY_FLAG_IBSS_RSN                     = BIT(8),
         WIPHY_FLAG_MESH_AUTH                    = BIT(10),
         WIPHY_FLAG_SUPPORTS_SCHED_SCAN          = BIT(11),
+        WIPHY_FLAG_ENFORCE_COMBINATIONS         = BIT(12),
+};
+
+/**
+ * struct ieee80211_iface_limit - limit on certain interface types
+ * @max: maximum number of interfaces of these types
+ * @types: interface types (bits)
+ */
+struct ieee80211_iface_limit {
+        u16 max;
+        u16 types;
+};
+
+/**
+ * struct ieee80211_iface_combination - possible interface combination
+ * @limits: limits for the given interface types
+ * @n_limits: number of limitations
+ * @num_different_channels: can use up to this many different channels
+ * @max_interfaces: maximum number of interfaces in total allowed in this
+ *      group
+ * @beacon_int_infra_match: In this combination, the beacon intervals
+ *      between infrastructure and AP types must match. This is required
+ *      only in special cases.
+ *
+ * These examples can be expressed as follows:
+ *
+ * Allow #STA <= 1, #AP <= 1, matching BI, channels = 1, 2 total:
+ *
+ *  struct ieee80211_iface_limit limits1[] = {
+ *      { .max = 1, .types = BIT(NL80211_IFTYPE_STATION), },
+ *      { .max = 1, .types = BIT(NL80211_IFTYPE_AP}, },
+ *  };
+ *  struct ieee80211_iface_combination combination1 = {
+ *      .limits = limits1,
+ *      .n_limits = ARRAY_SIZE(limits1),
+ *      .max_interfaces = 2,
+ *      .beacon_int_infra_match = true,
+ *  };
+ *
+ *
+ * Allow #{AP, P2P-GO} <= 8, channels = 1, 8 total:
+ *
+ *  struct ieee80211_iface_limit limits2[] = {
+ *      { .max = 8, .types = BIT(NL80211_IFTYPE_AP) |
+ *                           BIT(NL80211_IFTYPE_P2P_GO), },
+ *  };
+ *  struct ieee80211_iface_combination combination2 = {
+ *      .limits = limits2,
+ *      .n_limits = ARRAY_SIZE(limits2),
+ *      .max_interfaces = 8,
+ *      .num_different_channels = 1,
+ *  };
+ *
+ *
+ * Allow #STA <= 1, #{P2P-client,P2P-GO} <= 3 on two channels, 4 total.
+ * This allows for an infrastructure connection and three P2P connections.
+ *
+ *  struct ieee80211_iface_limit limits3[] = {
+ *      { .max = 1, .types = BIT(NL80211_IFTYPE_STATION), },
+ *      { .max = 3, .types = BIT(NL80211_IFTYPE_P2P_GO) |
+ *                           BIT(NL80211_IFTYPE_P2P_CLIENT), },
+ *  };
+ *  struct ieee80211_iface_combination combination3 = {
+ *      .limits = limits3,
+ *      .n_limits = ARRAY_SIZE(limits3),
+ *      .max_interfaces = 4,
+ *      .num_different_channels = 2,
+ *  };
+ */
+struct ieee80211_iface_combination {
+        const struct ieee80211_iface_limit *limits;
+        u32 num_different_channels;
+        u16 max_interfaces;
+        u8 n_limits;
+        bool beacon_int_infra_match;
 };
 
 struct mac_address {
@@ -1653,6 +1732,11 @@ struct wiphy_wowlan_support {
  * @priv: driver private data (sized according to wiphy_new() parameter)
  * @interface_modes: bitmask of interfaces types valid for this wiphy,
  *      must be set by driver
+ * @iface_combinations: Valid interface combinations array, should not
+ *      list single interface types.
+ * @n_iface_combinations: number of entries in @iface_combinations array.
+ * @software_iftypes: bitmask of software interface types, these are not
+ *      subject to any restrictions since they are purely managed in SW.
  * @flags: wiphy flags, see &enum wiphy_flags
  * @bss_priv_size: each BSS struct has private data allocated with it,
  *      this variable determines its size
@@ -1697,6 +1781,10 @@ struct wiphy {
 
         const struct ieee80211_txrx_stypes *mgmt_stypes;
 
+        const struct ieee80211_iface_combination *iface_combinations;
+        int n_iface_combinations;
+        u16 software_iftypes;
+
         u16 n_addresses;
 
         /* Supported interface modes, OR together BIT(NL80211_IFTYPE_...) */