[RFC,v5.4,1/3] mac80211: mlme: find auth challenge directly

Commit Message

Johannes Berg Oct. 14, 2022, 4:47 p.m. UTC

From: Johannes Berg <[e-mail]>

There's no need to parse all elements etc. just to find the
authentication challenge - use cfg80211_find_elem() instead.
This also allows us to remove WLAN_EID_CHALLENGE handling
from the element parsing entirely.

Link: https://lore.kernel.org/r/20210920154009.45f9b3a15722.Ice3159ffad03a007d6154cbf1fb3a8c48489e86f@changeid
Signed-off-by: Johannes Berg <[e-mail]>
---
 net/mac80211/ieee80211_i.h |  2 --
 net/mac80211/mlme.c        | 11 ++++++-----
 net/mac80211/util.c        |  4 ----
 3 files changed, 6 insertions(+), 11 deletions(-)

Comments

Johannes Berg Oct. 14, 2022, 4:59 p.m. UTC | #1

On Fri, 2022-10-14 at 18:47 +0200, Johannes Berg wrote:
> From: Johannes Berg <[e-mail]>
> 
> There's no need to parse all elements etc. just to find the
> authentication challenge - use cfg80211_find_elem() instead.
> This also allows us to remove WLAN_EID_CHALLENGE handling
> from the element parsing entirely.



>  	pos = mgmt->u.auth.variable;
> -	ieee802_11_parse_elems(pos, len - (pos - (u8 *)mgmt), false, &elems,
> -			       mgmt->bssid, auth_data->bss->bssid);
> 

And, I probably should've said that in the commit message, the multiple
BSSID element isn't valid in this frame either, so need to try to parse
it (last argument)

johannes

Patch

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 7747a6f46d29..3d5da7a97be4 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1460,7 +1460,6 @@  struct ieee802_11_elems {
 	const u8 *supp_rates;
 	const u8 *ds_params;
 	const struct ieee80211_tim_ie *tim;
-	const u8 *challenge;
 	const u8 *rsn;
 	const u8 *erp_info;
 	const u8 *ext_supp_rates;
@@ -1507,7 +1506,6 @@  struct ieee802_11_elems {
 	u8 ssid_len;
 	u8 supp_rates_len;
 	u8 tim_len;
-	u8 challenge_len;
 	u8 rsn_len;
 	u8 ext_supp_rates_len;
 	u8 wmm_info_len;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 5415e566e09d..aaec8a78b159 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2829,14 +2829,14 @@  static void ieee80211_auth_challenge(struct ieee80211_sub_if_data *sdata,
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_mgd_auth_data *auth_data = sdata->u.mgd.auth_data;
+	const struct element *challenge;
 	u8 *pos;
-	struct ieee802_11_elems elems;
 	u32 tx_flags = 0;
 
 	pos = mgmt->u.auth.variable;
-	ieee802_11_parse_elems(pos, len - (pos - (u8 *)mgmt), false, &elems,
-			       mgmt->bssid, auth_data->bss->bssid);
-	if (!elems.challenge)
+	challenge = cfg80211_find_elem(WLAN_EID_CHALLENGE, pos,
+				       len - (pos - (u8 *)mgmt));
+	if (!challenge)
 		return;
 	auth_data->expected_transaction = 4;
 	drv_mgd_prepare_tx(sdata->local, sdata, 0);
@@ -2844,7 +2844,8 @@  static void ieee80211_auth_challenge(struct ieee80211_sub_if_data *sdata,
 		tx_flags = IEEE80211_TX_CTL_REQ_TX_STATUS |
 			   IEEE80211_TX_INTFL_MLME_CONN_TX;
 	ieee80211_send_auth(sdata, 3, auth_data->algorithm, 0,
-			    elems.challenge - 2, elems.challenge_len + 2,
+			    (void *)challenge,
+			    challenge->datalen + sizeof(*challenge),
 			    auth_data->bss->bssid, auth_data->bss->bssid,
 			    auth_data->key, auth_data->key_len,
 			    auth_data->key_idx, tx_flags);
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index a529861256e6..1ba37f67a2a0 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1006,10 +1006,6 @@  _ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 			} else
 				elem_parse_failed = true;
 			break;
-		case WLAN_EID_CHALLENGE:
-			elems->challenge = pos;
-			elems->challenge_len = elen;
-			break;
 		case WLAN_EID_VENDOR_SPECIFIC:
 			if (elen >= 4 && pos[0] == 0x00 && pos[1] == 0x50 &&
 			    pos[2] == 0xf2) {