nl80211: Retrieve maxattr via genl for nl80211

Older kernel versions may not support all attributes and may refuse
commands that include them. To avoid sending too new attributes query
the highest supported attribute. This allows adding appropriate checks
where needed.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 39c9362d0a0e57e58b1118d2eb5040a1f197dc50..8313ac5943d22bfe43b7a21e6716ff91229a349b 100644 (file)
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -16,6 +16,7 @@
 #include <net/if.h>
 #include <netlink/genl/genl.h>
 #include <netlink/genl/ctrl.h>
+#include <netlink/genl/family.h>
 #ifdef CONFIG_LIBNL3_ROUTE
 #include <netlink/route/neighbour.h>
 #endif /* CONFIG_LIBNL3_ROUTE */
@@ -1938,6 +1939,8 @@ static int wpa_driver_nl80211_get_country(void *priv, char *alpha2)
 
 static int wpa_driver_nl80211_init_nl_global(struct nl80211_global *global)
 {
+       struct nl_cache *cache = NULL;
+       struct genl_family *family = NULL;
        int ret;
 
        global->nl_cb = nl_cb_alloc(NL_CB_DEFAULT);
@@ -2009,6 +2012,29 @@ static int wpa_driver_nl80211_init_nl_global(struct nl80211_global *global)
                /* Continue without vendor events */
        }
 
+       /* Resolve maxattr for kernel support checks */
+       ret = genl_ctrl_alloc_cache(global->nl, &cache);
+       if (ret < 0) {
+               wpa_printf(MSG_DEBUG,
+                          "nl80211: Could not allocate genl cache: %d (%s)",
+                          ret, nl_geterror(ret));
+               goto err;
+       }
+
+       family = genl_ctrl_search(cache, global->nl80211_id);
+       if (!family) {
+               wpa_printf(MSG_DEBUG,
+                          "nl80211: Could not get nl80211 family from cache: %d (%s)",
+                          ret, nl_geterror(ret));
+               goto err;
+       }
+
+       global->nl80211_maxattr = genl_family_get_maxattr(family);
+       wpa_printf(MSG_DEBUG, "nl80211: Maximum supported attribute ID: %u",
+                  global->nl80211_maxattr);
+       genl_family_put(family);
+       nl_cache_free(cache);
+
        nl_cb_set(global->nl_cb, NL_CB_SEQ_CHECK, NL_CB_CUSTOM,
                  no_seq_check, NULL);
        nl_cb_set(global->nl_cb, NL_CB_VALID, NL_CB_CUSTOM,
@@ -2021,6 +2047,8 @@ static int wpa_driver_nl80211_init_nl_global(struct nl80211_global *global)
        return 0;
 
 err:
+       genl_family_put(family);
+       nl_cache_free(cache);
        nl_destroy_handles(&global->nl_event);
        nl_destroy_handles(&global->nl);
        nl_cb_put(global->nl_cb);

diff --git a/src/drivers/driver_nl80211.h b/src/drivers/driver_nl80211.h
index 2b2bc9b11792b67b0c8b3b88d82c3e83e08e971f..1eb5656fff81d61d141c7fd4c2945ab718b6a5ec 100644 (file)
--- a/src/drivers/driver_nl80211.h
+++ b/src/drivers/driver_nl80211.h
@@ -32,6 +32,7 @@ struct nl80211_global {
        struct nl_cb *nl_cb;
        struct nl_sock *nl;
        int nl80211_id;
+       unsigned int nl80211_maxattr;
        int nlctrl_id;
        int ioctl_sock; /* socket for ioctl() use */