Subject: [PATCH] mac80211: Scale down to non-HT association with TKIP/WEP as pairwise cipher

As TKIP is not updated to new security needs which arise when
TKIP is used to encrypt A-MPDU aggregated data frames, IEEE802.11n
does not allow any cipher other than CCMP (Which has new extensions
defined) as pairwise cipher between HT peers.

When such configuration (TKIP/WEP in HT) is forced, we still
associate in non-HT mode (11a/b/g).

Signed-off-by: Vasanthakumar Thiagarajan <[email protected]>
---
net/mac80211/ieee80211_i.h | 1 +
net/mac80211/iface.c | 3 ++-
net/mac80211/mlme.c | 9 ++++++++-
net/mac80211/wext.c | 12 +++++++++++-
4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index f3eec98..5f8ad88 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -258,6 +258,7 @@ struct mesh_preq_queue {
#define IEEE80211_STA_AUTO_BSSID_SEL BIT(11)
#define IEEE80211_STA_AUTO_CHANNEL_SEL BIT(12)
#define IEEE80211_STA_PRIVACY_INVOKED BIT(13)
+#define IEEE80211_STA_TKIP_WEP_USED BIT(14)
/* flags for MLME request */
#define IEEE80211_STA_REQ_SCAN 0
#define IEEE80211_STA_REQ_DIRECT_PROBE 1
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 5abbc3f..19cfc0a 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -459,7 +459,8 @@ static int ieee80211_stop(struct net_device *dev)
synchronize_rcu();
skb_queue_purge(&sdata->u.sta.skb_queue);

- sdata->u.sta.flags &= ~IEEE80211_STA_PRIVACY_INVOKED;
+ sdata->u.sta.flags &= ~(IEEE80211_STA_PRIVACY_INVOKED |
+ IEEE80211_STA_TKIP_WEP_USED);
kfree(sdata->u.sta.extra_ie);
sdata->u.sta.extra_ie = NULL;
sdata->u.sta.extra_ie_len = 0;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index c75d0ea..4998dc5 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -391,10 +391,17 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata,
}

/* wmm support is a must to HT */
+ /*
+ * IEEE802.11n does not allow TKIP/WEP as pairwise
+ * ciphers in HT mode. We still associate in non-ht
+ * mode (11a/b/g) if any one of these ciphers is
+ * configured as pairwise.
+ */
if (wmm && (ifsta->flags & IEEE80211_STA_WMM_ENABLED) &&
sband->ht_cap.ht_supported &&
(ht_ie = ieee80211_bss_get_ie(bss, WLAN_EID_HT_INFORMATION)) &&
- ht_ie[1] >= sizeof(struct ieee80211_ht_info)) {
+ ht_ie[1] >= sizeof(struct ieee80211_ht_info) &&
+ (!(ifsta->flags & IEEE80211_STA_TKIP_WEP_USED))) {
struct ieee80211_ht_info *ht_info =
(struct ieee80211_ht_info *)(ht_ie + 2);
u16 cap = sband->ht_cap.cap;
diff --git a/net/mac80211/wext.c b/net/mac80211/wext.c
index 7162d58..011592f 100644
--- a/net/mac80211/wext.c
+++ b/net/mac80211/wext.c
@@ -903,12 +903,22 @@ static int ieee80211_ioctl_siwauth(struct net_device *dev,

switch (data->flags & IW_AUTH_INDEX) {
case IW_AUTH_WPA_VERSION:
- case IW_AUTH_CIPHER_PAIRWISE:
case IW_AUTH_CIPHER_GROUP:
case IW_AUTH_WPA_ENABLED:
case IW_AUTH_RX_UNENCRYPTED_EAPOL:
case IW_AUTH_KEY_MGMT:
break;
+ case IW_AUTH_CIPHER_PAIRWISE:
+ if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+ if (data->value & (IW_AUTH_CIPHER_WEP40 |
+ IW_AUTH_CIPHER_WEP104 | IW_AUTH_CIPHER_TKIP))
+ sdata->u.sta.flags |=
+ IEEE80211_STA_TKIP_WEP_USED;
+ else
+ sdata->u.sta.flags &=
+ ~IEEE80211_STA_TKIP_WEP_USED;
+ }
+ break;
case IW_AUTH_DROP_UNENCRYPTED:
sdata->drop_unencrypted = !!data->value;
break;
--
1.5.5.1



2008-12-23 17:06:06

by Johannes Berg

[permalink] [raw]
Subject: Re: [PATCH] mac80211: Scale down to non-HT association with TKIP/WEP as pairwise cipher

On Tue, 2008-12-23 at 21:30 +0530, Vasanthakumar Thiagarajan wrote:
> As TKIP is not updated to new security needs which arise when
> TKIP is used to encrypt A-MPDU aggregated data frames, IEEE802.11n
> does not allow any cipher other than CCMP (Which has new extensions
> defined) as pairwise cipher between HT peers.
>
> When such configuration (TKIP/WEP in HT) is forced, we still
> associate in non-HT mode (11a/b/g).
>
> Signed-off-by: Vasanthakumar Thiagarajan <[email protected]>

Ok, we'll revisit this when we do normal key config in cfg80211, until
then this looks good to me.

Acked-by: Johannes Berg <[email protected]>

> ---
> net/mac80211/ieee80211_i.h | 1 +
> net/mac80211/iface.c | 3 ++-
> net/mac80211/mlme.c | 9 ++++++++-
> net/mac80211/wext.c | 12 +++++++++++-
> 4 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index f3eec98..5f8ad88 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -258,6 +258,7 @@ struct mesh_preq_queue {
> #define IEEE80211_STA_AUTO_BSSID_SEL BIT(11)
> #define IEEE80211_STA_AUTO_CHANNEL_SEL BIT(12)
> #define IEEE80211_STA_PRIVACY_INVOKED BIT(13)
> +#define IEEE80211_STA_TKIP_WEP_USED BIT(14)
> /* flags for MLME request */
> #define IEEE80211_STA_REQ_SCAN 0
> #define IEEE80211_STA_REQ_DIRECT_PROBE 1
> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
> index 5abbc3f..19cfc0a 100644
> --- a/net/mac80211/iface.c
> +++ b/net/mac80211/iface.c
> @@ -459,7 +459,8 @@ static int ieee80211_stop(struct net_device *dev)
> synchronize_rcu();
> skb_queue_purge(&sdata->u.sta.skb_queue);
>
> - sdata->u.sta.flags &= ~IEEE80211_STA_PRIVACY_INVOKED;
> + sdata->u.sta.flags &= ~(IEEE80211_STA_PRIVACY_INVOKED |
> + IEEE80211_STA_TKIP_WEP_USED);
> kfree(sdata->u.sta.extra_ie);
> sdata->u.sta.extra_ie = NULL;
> sdata->u.sta.extra_ie_len = 0;
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index c75d0ea..4998dc5 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -391,10 +391,17 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata,
> }
>
> /* wmm support is a must to HT */
> + /*
> + * IEEE802.11n does not allow TKIP/WEP as pairwise
> + * ciphers in HT mode. We still associate in non-ht
> + * mode (11a/b/g) if any one of these ciphers is
> + * configured as pairwise.
> + */
> if (wmm && (ifsta->flags & IEEE80211_STA_WMM_ENABLED) &&
> sband->ht_cap.ht_supported &&
> (ht_ie = ieee80211_bss_get_ie(bss, WLAN_EID_HT_INFORMATION)) &&
> - ht_ie[1] >= sizeof(struct ieee80211_ht_info)) {
> + ht_ie[1] >= sizeof(struct ieee80211_ht_info) &&
> + (!(ifsta->flags & IEEE80211_STA_TKIP_WEP_USED))) {
> struct ieee80211_ht_info *ht_info =
> (struct ieee80211_ht_info *)(ht_ie + 2);
> u16 cap = sband->ht_cap.cap;
> diff --git a/net/mac80211/wext.c b/net/mac80211/wext.c
> index 7162d58..011592f 100644
> --- a/net/mac80211/wext.c
> +++ b/net/mac80211/wext.c
> @@ -903,12 +903,22 @@ static int ieee80211_ioctl_siwauth(struct net_device *dev,
>
> switch (data->flags & IW_AUTH_INDEX) {
> case IW_AUTH_WPA_VERSION:
> - case IW_AUTH_CIPHER_PAIRWISE:
> case IW_AUTH_CIPHER_GROUP:
> case IW_AUTH_WPA_ENABLED:
> case IW_AUTH_RX_UNENCRYPTED_EAPOL:
> case IW_AUTH_KEY_MGMT:
> break;
> + case IW_AUTH_CIPHER_PAIRWISE:
> + if (sdata->vif.type == NL80211_IFTYPE_STATION) {
> + if (data->value & (IW_AUTH_CIPHER_WEP40 |
> + IW_AUTH_CIPHER_WEP104 | IW_AUTH_CIPHER_TKIP))
> + sdata->u.sta.flags |=
> + IEEE80211_STA_TKIP_WEP_USED;
> + else
> + sdata->u.sta.flags &=
> + ~IEEE80211_STA_TKIP_WEP_USED;
> + }
> + break;
> case IW_AUTH_DROP_UNENCRYPTED:
> sdata->drop_unencrypted = !!data->value;
> break;

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