cfg80211/nl80211: support GTK rekey offload

In certain circumstances, like WoWLAN scenarios,
devices may implement (partial) GTK rekeying on
the device to avoid waking up the host for it.

In order to successfully go through GTK rekeying,
the KEK, KCK and the replay counter are required.

Add API to let the supplicant hand the parameters
to the driver which may store it for future GTK
rekey operations.

Note that, of course, if GTK rekeying is done by
the device, the EAP frame must not be passed up
to userspace, instead a rekey event needs to be
sent to let userspace update its replay counter.

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

1 files changed, 113 insertions, 0 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 50ff82aa4890..491b0ba40c43 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -176,6 +176,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
         [NL80211_ATTR_WOWLAN_TRIGGERS] = { .type = NLA_NESTED },
         [NL80211_ATTR_STA_PLINK_STATE] = { .type = NLA_U8 },
         [NL80211_ATTR_SCHED_SCAN_INTERVAL] = { .type = NLA_U32 },
+        [NL80211_ATTR_REKEY_DATA] = { .type = NLA_NESTED },
 };
 
 /* policy for the key attributes */
@@ -206,6 +207,14 @@ nl80211_wowlan_policy[NUM_NL80211_WOWLAN_TRIG] = {
         [NL80211_WOWLAN_TRIG_PKT_PATTERN] = { .type = NLA_NESTED },
 };
 
+/* policy for GTK rekey offload attributes */
+static const struct nla_policy
+nl80211_rekey_policy[NUM_NL80211_REKEY_DATA] = {
+        [NL80211_REKEY_DATA_KEK] = { .len = NL80211_KEK_LEN },
+        [NL80211_REKEY_DATA_KCK] = { .len = NL80211_KCK_LEN },
+        [NL80211_REKEY_DATA_REPLAY_CTR] = { .len = NL80211_REPLAY_CTR_LEN },
+};
+
 /* ifidx get helper */
 static int nl80211_get_ifidx(struct netlink_callback *cb)
 {
@@ -5408,6 +5417,57 @@ static int nl80211_set_wowlan(struct sk_buff *skb, struct genl_info *info)
         return err;
 }
 
+static int nl80211_set_rekey_data(struct sk_buff *skb, struct genl_info *info)
+{
+        struct cfg80211_registered_device *rdev = info->user_ptr[0];
+        struct net_device *dev = info->user_ptr[1];
+        struct wireless_dev *wdev = dev->ieee80211_ptr;
+        struct nlattr *tb[NUM_NL80211_REKEY_DATA];
+        struct cfg80211_gtk_rekey_data rekey_data;
+        int err;
+
+        if (!info->attrs[NL80211_ATTR_REKEY_DATA])
+                return -EINVAL;
+
+        err = nla_parse(tb, MAX_NL80211_REKEY_DATA,
+                        nla_data(info->attrs[NL80211_ATTR_REKEY_DATA]),
+                        nla_len(info->attrs[NL80211_ATTR_REKEY_DATA]),
+                        nl80211_rekey_policy);
+        if (err)
+                return err;
+
+        if (nla_len(tb[NL80211_REKEY_DATA_REPLAY_CTR]) != NL80211_REPLAY_CTR_LEN)
+                return -ERANGE;
+        if (nla_len(tb[NL80211_REKEY_DATA_KEK]) != NL80211_KEK_LEN)
+                return -ERANGE;
+        if (nla_len(tb[NL80211_REKEY_DATA_KCK]) != NL80211_KCK_LEN)
+                return -ERANGE;
+
+        memcpy(rekey_data.kek, nla_data(tb[NL80211_REKEY_DATA_KEK]),
+               NL80211_KEK_LEN);
+        memcpy(rekey_data.kck, nla_data(tb[NL80211_REKEY_DATA_KCK]),
+               NL80211_KCK_LEN);
+        memcpy(rekey_data.replay_ctr,
+               nla_data(tb[NL80211_REKEY_DATA_REPLAY_CTR]),
+               NL80211_REPLAY_CTR_LEN);
+
+        wdev_lock(wdev);
+        if (!wdev->current_bss) {
+                err = -ENOTCONN;
+                goto out;
+        }
+
+        if (!rdev->ops->set_rekey_data) {
+                err = -EOPNOTSUPP;
+                goto out;
+        }
+
+        err = rdev->ops->set_rekey_data(&rdev->wiphy, dev, &rekey_data);
+ out:
+        wdev_unlock(wdev);
+        return err;
+}
+
 #define NL80211_FLAG_NEED_WIPHY         0x01
 #define NL80211_FLAG_NEED_NETDEV        0x02
 #define NL80211_FLAG_NEED_RTNL          0x04
@@ -5939,6 +5999,14 @@ static struct genl_ops nl80211_ops[] = {
                 .internal_flags = NL80211_FLAG_NEED_WIPHY |
                                   NL80211_FLAG_NEED_RTNL,
         },
+        {
+                .cmd = NL80211_CMD_SET_REKEY_OFFLOAD,
+                .doit = nl80211_set_rekey_data,
+                .policy = nl80211_policy,
+                .flags = GENL_ADMIN_PERM,
+                .internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
+                                  NL80211_FLAG_NEED_RTNL,
+        },
 };
 
 static struct genl_multicast_group nl80211_mlme_mcgrp = {
@@ -6883,6 +6951,51 @@ nl80211_send_cqm_rssi_notify(struct cfg80211_registered_device *rdev,
         nlmsg_free(msg);
 }
 
+void nl80211_gtk_rekey_notify(struct cfg80211_registered_device *rdev,
+                              struct net_device *netdev, const u8 *bssid,
+                              const u8 *replay_ctr, gfp_t gfp)
+{
+        struct sk_buff *msg;
+        struct nlattr *rekey_attr;
+        void *hdr;
+
+        msg = nlmsg_new(NLMSG_GOODSIZE, gfp);
+        if (!msg)
+                return;
+
+        hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_SET_REKEY_OFFLOAD);
+        if (!hdr) {
+                nlmsg_free(msg);
+                return;
+        }
+
+        NLA_PUT_U32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx);
+        NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, netdev->ifindex);
+        NLA_PUT(msg, NL80211_ATTR_MAC, ETH_ALEN, bssid);
+
+        rekey_attr = nla_nest_start(msg, NL80211_ATTR_REKEY_DATA);
+        if (!rekey_attr)
+                goto nla_put_failure;
+
+        NLA_PUT(msg, NL80211_REKEY_DATA_REPLAY_CTR,
+                NL80211_REPLAY_CTR_LEN, replay_ctr);
+
+        nla_nest_end(msg, rekey_attr);
+
+        if (genlmsg_end(msg, hdr) < 0) {
+                nlmsg_free(msg);
+                return;
+        }
+
+        genlmsg_multicast_netns(wiphy_net(&rdev->wiphy), msg, 0,
+                                nl80211_mlme_mcgrp.id, gfp);
+        return;
+
+ nla_put_failure:
+        genlmsg_cancel(msg, hdr);
+        nlmsg_free(msg);
+}
+
 void
 nl80211_send_cqm_pktloss_notify(struct cfg80211_registered_device *rdev,
                                 struct net_device *netdev, const u8 *peer,