| Message ID | 20200820155858.351292-1-Jerome.Pouiller@silabs.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | [01/12] staging: wfx: fix BA when device is AP and MFP is enabled | expand |
On Thu, Aug 20, 2020 at 05:58:47PM +0200, Jerome Pouiller wrote: > From: Jérôme Pouiller <jerome.pouiller@silabs.com> > > The protection of the management frames is mainly done by mac80211. > However, frames for the management of the BlockAck sessions are directly > sent by the device. These frames have to be protected if MFP is in use. > So the driver has to pass the MFP configuration to the device. > > Until now, the BlockAck management frames were completely unprotected > whatever the status of the MFP negotiation. So, some devices dropped > these frames. > > The device has two knobs to control the MFP. One global and one per > station. Normally, the driver should always enable global MFP. Then it > should enable MFP on every station with which MFP was successfully > negotiated. Unfortunately, the older firmwares only provide the > global control. > > So, this patch enable global MFP as it is exposed in the beacon. Then it > marks every station with which the MFP is effective. > > Thus, the support for the old firmwares is not so bad. It may only > encounter some difficulties to negotiate BA sessions when the local > device (the AP) is MFP capable (ieee80211w=1) but the station is not. > The only solution for this case is to upgrade the firmware. > > Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com> > --- > drivers/staging/wfx/sta.c | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c > index ad63332f690c..9c1c8223a49f 100644 > --- a/drivers/staging/wfx/sta.c > +++ b/drivers/staging/wfx/sta.c > @@ -434,7 +434,7 @@ int wfx_sta_add(struct ieee80211_hw *hw, struct ieee80211_vif *vif, > wvif->link_id_map |= BIT(sta_priv->link_id); > WARN_ON(!sta_priv->link_id); > WARN_ON(sta_priv->link_id >= HIF_LINK_ID_MAX); > - hif_map_link(wvif, sta->addr, 0, sta_priv->link_id); > + hif_map_link(wvif, sta->addr, sta->mfp ? 2 : 0, sta_priv->link_id); > > return 0; > } > @@ -474,6 +474,25 @@ static int wfx_upload_ap_templates(struct wfx_vif *wvif) > return 0; > } > > +static void wfx_set_mfp_ap(struct wfx_vif *wvif) > +{ > + struct sk_buff *skb = ieee80211_beacon_get(wvif->wdev->hw, wvif->vif); > + const int ieoffset = offsetof(struct ieee80211_mgmt, u.beacon.variable); > + const u16 *ptr = (u16 *)cfg80211_find_ie(WLAN_EID_RSN, > + skb->data + ieoffset, > + skb->len - ieoffset); > + const int pairwise_cipher_suite_count_offset = 8 / sizeof(u16); > + const int pairwise_cipher_suite_size = 4 / sizeof(u16); > + const int akm_suite_size = 4 / sizeof(u16); > + > + if (ptr) { > + ptr += pairwise_cipher_suite_count_offset; > + ptr += 1 + pairwise_cipher_suite_size * *ptr; The value of "*ptr" comes from skb->data. How do we know that it doesn't point to something beyond the end of the skb->data buffer? > + ptr += 1 + akm_suite_size * *ptr; > + hif_set_mfp(wvif, *ptr & BIT(7), *ptr & BIT(6)); > + } > +} regards, dan carpenter
On Monday 24 August 2020 11:50:42 CEST Dan Carpenter wrote: > On Thu, Aug 20, 2020 at 05:58:47PM +0200, Jerome Pouiller wrote: > > From: Jérôme Pouiller <jerome.pouiller@silabs.com> > > > > The protection of the management frames is mainly done by mac80211. > > However, frames for the management of the BlockAck sessions are directly > > sent by the device. These frames have to be protected if MFP is in use. > > So the driver has to pass the MFP configuration to the device. > > > > Until now, the BlockAck management frames were completely unprotected > > whatever the status of the MFP negotiation. So, some devices dropped > > these frames. > > > > The device has two knobs to control the MFP. One global and one per > > station. Normally, the driver should always enable global MFP. Then it > > should enable MFP on every station with which MFP was successfully > > negotiated. Unfortunately, the older firmwares only provide the > > global control. > > > > So, this patch enable global MFP as it is exposed in the beacon. Then it > > marks every station with which the MFP is effective. > > > > Thus, the support for the old firmwares is not so bad. It may only > > encounter some difficulties to negotiate BA sessions when the local > > device (the AP) is MFP capable (ieee80211w=1) but the station is not. > > The only solution for this case is to upgrade the firmware. > > > > Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com> > > --- > > drivers/staging/wfx/sta.c | 22 +++++++++++++++++++++- > > 1 file changed, 21 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c > > index ad63332f690c..9c1c8223a49f 100644 > > --- a/drivers/staging/wfx/sta.c > > +++ b/drivers/staging/wfx/sta.c > > @@ -434,7 +434,7 @@ int wfx_sta_add(struct ieee80211_hw *hw, struct ieee80211_vif *vif, > > wvif->link_id_map |= BIT(sta_priv->link_id); > > WARN_ON(!sta_priv->link_id); > > WARN_ON(sta_priv->link_id >= HIF_LINK_ID_MAX); > > - hif_map_link(wvif, sta->addr, 0, sta_priv->link_id); > > + hif_map_link(wvif, sta->addr, sta->mfp ? 2 : 0, sta_priv->link_id); > > > > return 0; > > } > > @@ -474,6 +474,25 @@ static int wfx_upload_ap_templates(struct wfx_vif *wvif) > > return 0; > > } > > > > +static void wfx_set_mfp_ap(struct wfx_vif *wvif) > > +{ > > + struct sk_buff *skb = ieee80211_beacon_get(wvif->wdev->hw, wvif->vif); > > + const int ieoffset = offsetof(struct ieee80211_mgmt, u.beacon.variable); > > + const u16 *ptr = (u16 *)cfg80211_find_ie(WLAN_EID_RSN, > > + skb->data + ieoffset, > > + skb->len - ieoffset); > > + const int pairwise_cipher_suite_count_offset = 8 / sizeof(u16); > > + const int pairwise_cipher_suite_size = 4 / sizeof(u16); > > + const int akm_suite_size = 4 / sizeof(u16); > > + > > + if (ptr) { > > + ptr += pairwise_cipher_suite_count_offset; > > + ptr += 1 + pairwise_cipher_suite_size * *ptr; > > The value of "*ptr" comes from skb->data. How do we know that it > doesn't point to something beyond the end of the skb->data buffer? I think the beacon come from hostapd (or any userspace application with the necessary permissions). Indeed, it could be corrupted. I have noticed that WLAN_EID_RSN is parsed at multiple places in the kernel and I haven't seen any particular check :( (and WLAN_EID_RSN is probably not the only dangerous IE). Anyway, I am going to add a few checks on values of ptr. > > + ptr += 1 + akm_suite_size * *ptr; > > + hif_set_mfp(wvif, *ptr & BIT(7), *ptr & BIT(6)); > > + } > > +}
diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c index ad63332f690c..9c1c8223a49f 100644 --- a/drivers/staging/wfx/sta.c +++ b/drivers/staging/wfx/sta.c @@ -434,7 +434,7 @@ int wfx_sta_add(struct ieee80211_hw *hw, struct ieee80211_vif *vif, wvif->link_id_map |= BIT(sta_priv->link_id); WARN_ON(!sta_priv->link_id); WARN_ON(sta_priv->link_id >= HIF_LINK_ID_MAX); - hif_map_link(wvif, sta->addr, 0, sta_priv->link_id); + hif_map_link(wvif, sta->addr, sta->mfp ? 2 : 0, sta_priv->link_id); return 0; } @@ -474,6 +474,25 @@ static int wfx_upload_ap_templates(struct wfx_vif *wvif) return 0; } +static void wfx_set_mfp_ap(struct wfx_vif *wvif) +{ + struct sk_buff *skb = ieee80211_beacon_get(wvif->wdev->hw, wvif->vif); + const int ieoffset = offsetof(struct ieee80211_mgmt, u.beacon.variable); + const u16 *ptr = (u16 *)cfg80211_find_ie(WLAN_EID_RSN, + skb->data + ieoffset, + skb->len - ieoffset); + const int pairwise_cipher_suite_count_offset = 8 / sizeof(u16); + const int pairwise_cipher_suite_size = 4 / sizeof(u16); + const int akm_suite_size = 4 / sizeof(u16); + + if (ptr) { + ptr += pairwise_cipher_suite_count_offset; + ptr += 1 + pairwise_cipher_suite_size * *ptr; + ptr += 1 + akm_suite_size * *ptr; + hif_set_mfp(wvif, *ptr & BIT(7), *ptr & BIT(6)); + } +} + int wfx_start_ap(struct ieee80211_hw *hw, struct ieee80211_vif *vif) { struct wfx_vif *wvif = (struct wfx_vif *)vif->drv_priv; @@ -488,6 +507,7 @@ int wfx_start_ap(struct ieee80211_hw *hw, struct ieee80211_vif *vif) ret = hif_start(wvif, &vif->bss_conf, wvif->channel); if (ret > 0) return -EIO; + wfx_set_mfp_ap(wvif); return ret; }