mac80211: stop using pointers as userspace cookies

Even if the pointers are really only accessible to root and used
pretty much only by wpa_supplicant, this is still not great; even
for debugging it'd be easier to have something that's easier to
read and guaranteed to never get reused.

With the recent change to make mac80211 create an ack_skb for the
mgmt-tx path this becomes possible, only the client probe method
needs to also allocate an ack_skb, and we can store the cookie in
that skb.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 39e864b..7466c55 100644 (file)
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -874,6 +874,9 @@ struct ieee80211_tx_info {
                        u32 flags;
                        /* 4 bytes free */
                } control;
+               struct {
+                       u64 cookie;
+               } ack;
                struct {
                        struct ieee80211_tx_rate rates[IEEE80211_TX_MAX_RATES];
                        s32 ack_signal;

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 5ba528f..1a17d32 100644 (file)
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2546,6 +2546,19 @@ static bool ieee80211_coalesce_started_roc(struct ieee80211_local *local,
        return true;
 }
 
+static u64 ieee80211_mgmt_tx_cookie(struct ieee80211_local *local)
+{
+       lockdep_assert_held(&local->mtx);
+
+       local->roc_cookie_counter++;
+
+       /* wow, you wrapped 64 bits ... more likely a bug */
+       if (WARN_ON(local->roc_cookie_counter == 0))
+               local->roc_cookie_counter++;
+
+       return local->roc_cookie_counter;
+}
+
 static int ieee80211_start_roc_work(struct ieee80211_local *local,
                                    struct ieee80211_sub_if_data *sdata,
                                    struct ieee80211_channel *channel,
@@ -2583,7 +2596,6 @@ static int ieee80211_start_roc_work(struct ieee80211_local *local,
        roc->req_duration = duration;
        roc->frame = txskb;
        roc->type = type;
-       roc->mgmt_tx_cookie = (unsigned long)txskb;
        roc->sdata = sdata;
        INIT_DELAYED_WORK(&roc->work, ieee80211_sw_roc_work);
        INIT_LIST_HEAD(&roc->dependents);
@@ -2593,17 +2605,10 @@ static int ieee80211_start_roc_work(struct ieee80211_local *local,
         * or the SKB (for mgmt TX)
         */
        if (!txskb) {
-               /* local->mtx protects this */
-               local->roc_cookie_counter++;
-               roc->cookie = local->roc_cookie_counter;
-               /* wow, you wrapped 64 bits ... more likely a bug */
-               if (WARN_ON(roc->cookie == 0)) {
-                       roc->cookie = 1;
-                       local->roc_cookie_counter++;
-               }
+               roc->cookie = ieee80211_mgmt_tx_cookie(local);
                *cookie = roc->cookie;
        } else {
-               *cookie = (unsigned long)txskb;
+               roc->mgmt_tx_cookie = *cookie;
        }
 
        /* if there's one pending or we're scanning, queue this one */
@@ -3284,6 +3289,36 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
        return err;
 }
 
+static struct sk_buff *ieee80211_make_ack_skb(struct ieee80211_local *local,
+                                             struct sk_buff *skb, u64 *cookie,
+                                             gfp_t gfp)
+{
+       unsigned long spin_flags;
+       struct sk_buff *ack_skb;
+       int id;
+
+       ack_skb = skb_copy(skb, gfp);
+       if (!ack_skb)
+               return ERR_PTR(-ENOMEM);
+
+       spin_lock_irqsave(&local->ack_status_lock, spin_flags);
+       id = idr_alloc(&local->ack_status_frames, ack_skb,
+                      1, 0x10000, GFP_ATOMIC);
+       spin_unlock_irqrestore(&local->ack_status_lock, spin_flags);
+
+       if (id < 0) {
+               kfree_skb(ack_skb);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       IEEE80211_SKB_CB(skb)->ack_frame_id = id;
+
+       *cookie = ieee80211_mgmt_tx_cookie(local);
+       IEEE80211_SKB_CB(ack_skb)->ack.cookie = *cookie;
+
+       return ack_skb;
+}
+
 static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev,
                             struct cfg80211_mgmt_tx_params *params,
                             u64 *cookie)
@@ -3429,40 +3464,22 @@ static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev,
        skb->dev = sdata->dev;
 
        if (!params->dont_wait_for_ack) {
-               unsigned long spin_flags;
-               int id;
-
-               /* make a copy to preserve the original cookie (in case the
-                * driver decides to reallocate the skb) and the frame contents
+               /* make a copy to preserve the frame contents
                 * in case of encryption.
                 */
-               ack_skb = skb_copy(skb, GFP_KERNEL);
-               if (!ack_skb) {
-                       ret = -ENOMEM;
-                       kfree_skb(skb);
-                       goto out_unlock;
-               }
-
-               spin_lock_irqsave(&local->ack_status_lock, spin_flags);
-               id = idr_alloc(&local->ack_status_frames, ack_skb,
-                              1, 0x10000, GFP_ATOMIC);
-               spin_unlock_irqrestore(&local->ack_status_lock, spin_flags);
-
-               if (id < 0) {
-                       ret = -ENOMEM;
-                       kfree_skb(ack_skb);
+               ack_skb = ieee80211_make_ack_skb(local, skb, cookie,
+                                                GFP_KERNEL);
+               if (IS_ERR(ack_skb)) {
+                       ret = PTR_ERR(ack_skb);
                        kfree_skb(skb);
                        goto out_unlock;
                }
-
-               IEEE80211_SKB_CB(skb)->ack_frame_id = id;
        } else {
                /* for cookie below */
                ack_skb = skb;
        }
 
        if (!need_offchan) {
-               *cookie = (unsigned long)ack_skb;
                ieee80211_tx_skb(sdata, skb);
                ret = 0;
                goto out_unlock;
@@ -3555,7 +3572,7 @@ static int ieee80211_probe_client(struct wiphy *wiphy, struct net_device *dev,
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_qos_hdr *nullfunc;
-       struct sk_buff *skb;
+       struct sk_buff *skb, *ack_skb;
        int size = sizeof(*nullfunc);
        __le16 fc;
        bool qos;
@@ -3563,20 +3580,24 @@ static int ieee80211_probe_client(struct wiphy *wiphy, struct net_device *dev,
        struct sta_info *sta;
        struct ieee80211_chanctx_conf *chanctx_conf;
        enum ieee80211_band band;
+       int ret;
+
+       /* the lock is needed to assign the cookie later */
+       mutex_lock(&local->mtx);
 
        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        if (WARN_ON(!chanctx_conf)) {
-               rcu_read_unlock();
-               return -EINVAL;
+               ret = -EINVAL;
+               goto unlock;
        }
        band = chanctx_conf->def.chan->band;
        sta = sta_info_get_bss(sdata, peer);
        if (sta) {
                qos = sta->sta.wme;
        } else {
-               rcu_read_unlock();
-               return -ENOLINK;
+               ret = -ENOLINK;
+               goto unlock;
        }
 
        if (qos) {
@@ -3592,8 +3613,8 @@ static int ieee80211_probe_client(struct wiphy *wiphy, struct net_device *dev,
 
        skb = dev_alloc_skb(local->hw.extra_tx_headroom + size);
        if (!skb) {
-               rcu_read_unlock();
-               return -ENOMEM;
+               ret = -ENOMEM;
+               goto unlock;
        }
 
        skb->dev = dev;
@@ -3619,13 +3640,23 @@ static int ieee80211_probe_client(struct wiphy *wiphy, struct net_device *dev,
        if (qos)
                nullfunc->qos_ctrl = cpu_to_le16(7);
 
+       ack_skb = ieee80211_make_ack_skb(local, skb, cookie, GFP_ATOMIC);
+       if (IS_ERR(ack_skb)) {
+               kfree_skb(skb);
+               ret = PTR_ERR(ack_skb);
+               goto unlock;
+       }
+
        local_bh_disable();
        ieee80211_xmit(sdata, sta, skb);
        local_bh_enable();
+
+       ret = 0;
+unlock:
        rcu_read_unlock();
+       mutex_unlock(&local->mtx);
 
-       *cookie = (unsigned long) skb;
-       return 0;
+       return ret;
 }
 
 static int ieee80211_cfg_get_channel(struct wiphy *wiphy,

diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index 56b73e0..67c4287 100644 (file)
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -471,15 +471,23 @@ static void ieee80211_report_ack_skb(struct ieee80211_local *local,
        }
 
        if (info->flags & IEEE80211_TX_INTFL_NL80211_FRAME_TX) {
+               u64 cookie = IEEE80211_SKB_CB(skb)->ack.cookie;
                struct ieee80211_sub_if_data *sdata;
+               struct ieee80211_hdr *hdr = (void *)skb->data;
 
                rcu_read_lock();
                sdata = ieee80211_sdata_from_skb(local, skb);
-               if (sdata)
-                       cfg80211_mgmt_tx_status(&sdata->wdev,
-                                               (unsigned long)skb,
-                                               skb->data, skb->len,
-                                               acked, GFP_ATOMIC);
+               if (sdata) {
+                       if (ieee80211_is_nullfunc(hdr->frame_control) ||
+                           ieee80211_is_qos_nullfunc(hdr->frame_control))
+                               cfg80211_probe_status(sdata->dev, hdr->addr1,
+                                                     cookie, acked,
+                                                     GFP_ATOMIC);
+                       else
+                               cfg80211_mgmt_tx_status(&sdata->wdev, cookie,
+                                                       skb->data, skb->len,
+                                                       acked, GFP_ATOMIC);
+               }
                rcu_read_unlock();
 
                dev_kfree_skb_any(skb);
@@ -499,11 +507,8 @@ static void ieee80211_report_used_skb(struct ieee80211_local *local,
        if (dropped)
                acked = false;
 
-       if (info->flags & (IEEE80211_TX_INTFL_NL80211_FRAME_TX |
-                          IEEE80211_TX_INTFL_MLME_CONN_TX) &&
-           !info->ack_frame_id) {
+       if (info->flags & IEEE80211_TX_INTFL_MLME_CONN_TX) {
                struct ieee80211_sub_if_data *sdata;
-               u64 cookie = (unsigned long)skb;
 
                rcu_read_lock();
 
@@ -525,10 +530,6 @@ static void ieee80211_report_used_skb(struct ieee80211_local *local,
                                ieee80211_mgd_conn_tx_status(sdata,
                                                             hdr->frame_control,
                                                             acked);
-               } else if (ieee80211_is_nullfunc(hdr->frame_control) ||
-                          ieee80211_is_qos_nullfunc(hdr->frame_control)) {
-                       cfg80211_probe_status(sdata->dev, hdr->addr1,
-                                             cookie, acked, GFP_ATOMIC);
                } else {
                        /* we assign ack frame ID for the others */
                        WARN_ON(1);