[MAC80211]: rework key handling

This moves all the key handling code out from ieee80211_ioctl.c
into key.c and also does the following changes including documentation
updates in mac80211.h:

 1) Turn off hardware acceleration for keys when the interface
    is down. This is necessary because otherwise monitor
    interfaces could be decrypting frames for other interfaces
    that are down at the moment. Also, it should go some way
    towards better suspend/resume support, in any case the
    routines used here could be used for that as well.
    Additionally, this makes the driver interface nicer, keys
    for a specific local MAC address are only ever present
    while an interface with that MAC address is enabled.

 2) Change driver set_key() callback interface to allow only
    return values of -ENOSPC, -EOPNOTSUPP and 0, warn on all
    other return values. This allows debugging the stack when
    a driver notices it's handed a key while it is down.

 3) Invert the flag meaning to KEY_FLAG_UPLOADED_TO_HARDWARE.

 4) Remove REMOVE_ALL_KEYS command as it isn't used nor do we
    want to use it, we'll use DISABLE_KEY for each key. It is
    hard to use REMOVE_ALL_KEYS because we can handle multiple
    virtual interfaces with different key configuration, so we'd
    have to keep track of a lot of state for this and that isn't
    worth it.

 5) Warn when disabling a key fails, it musn't.

 6) Remove IEEE80211_HW_NO_TKIP_WMM_HWACCEL in favour of per-key
    IEEE80211_KEY_FLAG_WMM_STA to let driver sort it out itself.

 7) Tell driver that a (non-WEP) key is used only for transmission
    by using an all-zeroes station MAC address when configuring.

 8) Change the set_key() callback to have access to the local MAC
    address the key is being added for.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 241 insertions, 2 deletions

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 843d157..178f00c 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -2,25 +2,198 @@
  * Copyright 2002-2005, Instant802 Networks, Inc.
  * Copyright 2005-2006, Devicescape Software, Inc.
  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
+ * Copyright 2007	Johannes Berg <johannes@sipsolutions.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 
+#include <linux/if_ether.h>
+#include <linux/etherdevice.h>
+#include <linux/list.h>
 #include <net/mac80211.h>
 #include "ieee80211_i.h"
 #include "debugfs_key.h"
 #include "aes_ccm.h"
 
+
+/*
+ * Key handling basics
+ *
+ * Key handling in mac80211 is done based on per-interface (sub_if_data)
+ * keys and per-station keys. Since each station belongs to an interface,
+ * each station key also belongs to that interface.
+ *
+ * Hardware acceleration is done on a best-effort basis, for each key
+ * that is eligible the hardware is asked to enable that key but if
+ * it cannot do that they key is simply kept for software encryption.
+ * There is currently no way of knowing this except by looking into
+ * debugfs.
+ *
+ * All operations here are called under RTNL so no extra locking is
+ * required.
+ */
+
+static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
+static const u8 zero_addr[ETH_ALEN];
+
+static const u8 *get_mac_for_key(struct ieee80211_key *key)
+{
+	const u8 *addr = bcast_addr;
+
+	/*
+	 * If we're an AP we won't ever receive frames with a non-WEP
+	 * group key so we tell the driver that by using the zero MAC
+	 * address to indicate a transmit-only key.
+	 */
+	if (key->conf.alg != ALG_WEP &&
+	    (key->sdata->type == IEEE80211_IF_TYPE_AP ||
+	     key->sdata->type == IEEE80211_IF_TYPE_VLAN))
+		addr = zero_addr;
+
+	if (key->sta)
+		addr = key->sta->addr;
+
+	return addr;
+}
+
+static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
+{
+	const u8 *addr;
+	int ret;
+
+	if (!key->local->ops->set_key)
+		return;
+
+	addr = get_mac_for_key(key);
+
+	ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
+				       key->sdata->dev->dev_addr, addr,
+				       &key->conf);
+
+	WARN_ON(!ret && (key->conf.hw_key_idx == HW_KEY_IDX_INVALID));
+
+	if (!ret)
+		key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
+
+	if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
+		printk(KERN_ERR "mac80211-%s: failed to set key "
+		       "(%d, " MAC_FMT ") to hardware (%d)\n",
+		       wiphy_name(key->local->hw.wiphy),
+		       key->conf.keyidx, MAC_ARG(addr), ret);
+}
+
+static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
+{
+	const u8 *addr;
+	int ret;
+
+	if (!key->local->ops->set_key)
+		return;
+
+	if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
+		return;
+
+	addr = get_mac_for_key(key);
+
+	ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
+				       key->sdata->dev->dev_addr, addr,
+				       &key->conf);
+
+	if (ret)
+		printk(KERN_ERR "mac80211-%s: failed to remove key "
+		       "(%d, " MAC_FMT ") from hardware (%d)\n",
+		       wiphy_name(key->local->hw.wiphy),
+		       key->conf.keyidx, MAC_ARG(addr), ret);
+
+	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
+	key->conf.hw_key_idx = HW_KEY_IDX_INVALID;
+}
+
 struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
-					  int idx, size_t key_len, gfp_t flags)
+					  struct sta_info *sta,
+					  ieee80211_key_alg alg,
+					  int idx,
+					  size_t key_len,
+					  const u8 *key_data)
 {
 	struct ieee80211_key *key;
 
-	key = kzalloc(sizeof(struct ieee80211_key) + key_len, flags);
+	BUG_ON(alg == ALG_NONE);
+
+	key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 	if (!key)
 		return NULL;
+
+	/*
+	 * Default to software encryption; we'll later upload the
+	 * key to the hardware if possible.
+	 */
+	key->conf.hw_key_idx = HW_KEY_IDX_INVALID;
+	key->conf.flags = 0;
+	key->flags = 0;
+
+	key->conf.alg = alg;
+	key->conf.keyidx = idx;
+	key->conf.keylen = key_len;
+	memcpy(key->conf.key, key_data, key_len);
+
+	key->local = sdata->local;
+	key->sdata = sdata;
+	key->sta = sta;
+
+	if (alg == ALG_CCMP) {
+		/*
+		 * Initialize AES key state here as an optimization so that
+		 * it does not need to be initialized for every packet.
+		 */
+		key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
+		if (!key->u.ccmp.tfm) {
+			ieee80211_key_free(key);
+			return NULL;
+		}
+	}
+
+	ieee80211_debugfs_key_add(key->local, key);
+
+	if (sta) {
+		ieee80211_debugfs_key_sta_link(key, sta);
+		sta->key = key;
+		/*
+		 * some hardware cannot handle TKIP with QoS, so
+		 * we indicate whether QoS could be in use.
+		 */
+		if (sta->flags & WLAN_STA_WME)
+			key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
+	} else {
+		if (sdata->type == IEEE80211_IF_TYPE_STA) {
+			struct sta_info *ap;
+
+			/* same here, the AP could be using QoS */
+			ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
+			if (ap) {
+				if (ap->flags & WLAN_STA_WME)
+					key->conf.flags |=
+						IEEE80211_KEY_FLAG_WMM_STA;
+				sta_info_put(ap);
+			}
+		}
+
+		if (idx >= 0 && idx < NUM_DEFAULT_KEYS) {
+			if (!sdata->keys[idx])
+				sdata->keys[idx] = key;
+			else
+				WARN_ON(1);
+		} else
+			WARN_ON(1);
+	}
+
+	list_add(&key->list, &sdata->key_list);
+
+	if (netif_running(key->sdata->dev))
+		ieee80211_key_enable_hw_accel(key);
+
 	return key;
 }
 
@@ -29,8 +202,74 @@ void ieee80211_key_free(struct ieee80211_key *key)
 	if (!key)
 		return;
 
+	ieee80211_key_disable_hw_accel(key);
+
+	if (key->sta) {
+		key->sta->key = NULL;
+	} else {
+		if (key->sdata->default_key == key)
+			ieee80211_set_default_key(key->sdata, -1);
+		if (key->conf.keyidx >= 0 &&
+		    key->conf.keyidx < NUM_DEFAULT_KEYS)
+			key->sdata->keys[key->conf.keyidx] = NULL;
+		else
+			WARN_ON(1);
+	}
+
 	if (key->conf.alg == ALG_CCMP)
 		ieee80211_aes_key_free(key->u.ccmp.tfm);
 	ieee80211_debugfs_key_remove(key);
+
+	list_del(&key->list);
+
 	kfree(key);
 }
+
+void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
+{
+	struct ieee80211_key *key = NULL;
+
+	if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
+		key = sdata->keys[idx];
+
+	if (sdata->default_key != key) {
+		ieee80211_debugfs_key_remove_default(sdata);
+
+		sdata->default_key = key;
+
+		if (sdata->default_key)
+			ieee80211_debugfs_key_add_default(sdata);
+
+		if (sdata->local->ops->set_key_idx)
+			sdata->local->ops->set_key_idx(
+				local_to_hw(sdata->local), idx);
+	}
+}
+
+void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_key *key, *tmp;
+
+	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
+		ieee80211_key_free(key);
+}
+
+void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_key *key;
+
+	WARN_ON(!netif_running(sdata->dev));
+	if (!netif_running(sdata->dev))
+		return;
+
+	list_for_each_entry(key, &sdata->key_list, list)
+		ieee80211_key_enable_hw_accel(key);
+}
+
+void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_key *key;
+
+	list_for_each_entry(key, &sdata->key_list, list)
+		ieee80211_key_disable_hw_accel(key);
+}