The validation of the multi-AP IE in hostapd is not very complete.
* When the IE is incorrectly constructed, return WLAN_STATUS_INVALID_IE.
This might not be entirely the right thing to do, since that status is
in principle reserved for IEs specified in IEEE 802.11-2016, but it
makes sense to use that for incorrect subelements as well, and it's done
in other places.
* When the AP is configured as fronthaul-only, association requests for
backhaul STA are rejected.
* When the AP is configured as backhaul-only, association requests
without backhaul STA are rejected.
* A multi-AP IE with a value different than MULTI_AP_BACKHAUL_STA is
ignored (i.e. treated the same as if it was missing).
* Rejections use reason WLAN_STATUS_ASSOC_DENIED_UNSPEC instead of
WLAN_STATUS_UNSPECIFIED_FAILURE - that seems a better match with the
IEEE 802.11-2016 specification.
* Set the WLAN_STA_MULTI_AP based on the IE, independent of whether it
is a backhaul or fronthaul AP. This makes sure that the Association
Response contains the IE even if it is a rejection.
None of the above is explicitly specified in the Multi-AP Specification.
However, it is pretty clear that we only want backhaul stations on a
backhaul-only AP and only fronthaul stations on a fronhaul-only AP,
otherwise the distinction is pointless.
Finally, rename hostapd_validate_multi_ap_ie() to check_multi_ap() and
directly give it the multi_ap_ie as argument rather than the
ieee802_11_elems, since that is how most other functions in that file
work.
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@xxxxxxx>
Cc: Venkateswara Naralasetty <vnaralas@xxxxxxxxxxxxxx>
---
src/ap/ieee802_11.c | 58 +++++++++++++++++++++++++++++++--------------
1 file changed, 40 insertions(+), 18 deletions(-)
diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c
index fec5882e0..63ab27cb3 100644
--- a/src/ap/ieee802_11.c
+++ b/src/ap/ieee802_11.c
@@ -2224,31 +2224,53 @@ static u16 check_wmm(struct hostapd_data *hapd, struct sta_info *sta,
return WLAN_STATUS_SUCCESS;
}
-static u16 hostapd_validate_multi_ap_ie(struct hostapd_data *hapd,
- struct sta_info *sta,
- struct ieee802_11_elems *elems)
+static u16 check_multi_ap(struct hostapd_data *hapd, struct sta_info *sta,
+ const u8 *multi_ap_ie, size_t multi_ap_len)
{
- const u8 *pos, *map_sub_elem;
- size_t len;
+ u8 multi_ap_value = 0;
- if (!hapd->conf->multi_ap || !elems->multi_ap)
+ sta->flags &= ~WLAN_STA_MULTI_AP;
+
+ if (!hapd->conf->multi_ap)
return WLAN_STATUS_SUCCESS;
- pos = elems->multi_ap + 4;/* OUI[3] and OUT_TYPE 1 */
- len = elems->multi_ap_len - 4;
+ if (multi_ap_ie) {
+ const u8 *multi_ap_subelem = get_ie(multi_ap_ie + 4,
+ multi_ap_len - 4,
+ MULTI_AP_SUB_ELEM_TYPE);
+ if (multi_ap_subelem &&
+ multi_ap_subelem[1] == 1)
+ multi_ap_value = multi_ap_subelem[2];
+ else {
+ hostapd_logger(hapd, sta->addr,
+ HOSTAPD_MODULE_IEEE80211,
+ HOSTAPD_LEVEL_INFO,
+ "Multi-AP IE has missing or invalid Multi-AP subelement");
+ return WLAN_STATUS_INVALID_IE;
+ }
+ }
- sta->flags &= ~WLAN_STA_MULTI_AP;
+ if (multi_ap_value == MULTI_AP_BACKHAUL_STA)
+ sta->flags |= WLAN_STA_MULTI_AP;
- map_sub_elem = get_ie(pos, len, MULTI_AP_SUB_ELEM_TYPE);
+ if (hapd->conf->multi_ap & BACKHAUL_BSS &&
+ multi_ap_value == MULTI_AP_BACKHAUL_STA)
+ return WLAN_STATUS_SUCCESS;
- if (map_sub_elem) {
- if (map_sub_elem[1] < 1)
- return WLAN_STATUS_UNSPECIFIED_FAILURE;
- if (map_sub_elem[2] & MULTI_AP_BACKHAUL_STA)
- sta->flags |= WLAN_STA_MULTI_AP;
+ if (hapd->conf->multi_ap & FRONTHAUL_BSS) {
+ if (multi_ap_value == MULTI_AP_BACKHAUL_STA) {
+ hostapd_logger(hapd, sta->addr,
+ HOSTAPD_MODULE_IEEE80211,
+ HOSTAPD_LEVEL_INFO,
+ "Backhaul STA tries to associate with fronthaul-only BSS");
+ return WLAN_STATUS_ASSOC_DENIED_UNSPEC;
+ }
+ return WLAN_STATUS_SUCCESS;
}
-
- return WLAN_STATUS_SUCCESS;
+ hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_IEEE80211,
+ HOSTAPD_LEVEL_INFO,
+ "Non-Multi-AP STA tries to associate with backhaul-only BSS");
+ return WLAN_STATUS_ASSOC_DENIED_UNSPEC;
}
static u16 copy_supp_rates(struct hostapd_data *hapd, struct sta_info *sta,
@@ -2507,7 +2529,7 @@ static u16 check_assoc_ies(struct hostapd_data *hapd, struct sta_info *sta,
if (resp != WLAN_STATUS_SUCCESS)
return resp;
- resp = hostapd_validate_multi_ap_ie(hapd, sta, &elems);
+ resp = check_multi_ap(hapd, sta, elems.multi_ap, elems.multi_ap_len);
if (resp != WLAN_STATUS_SUCCESS)
return resp;
--
2.19.2
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