Subject: Re: [PATCH 1/2] airo: fix IW_AUTH_ALG_OPEN_SYSTEM

From: Ondrej Zary <[email-masked]>
Date: Wed, 2 Sep 2015 00:21:58 +0200

On Tuesday 01 September 2015 02:04:43 Dan Williams wrote:
> On Tue, 2015-09-01 at 00:12 +0200, Ondrej Zary wrote:
> > On Monday 31 August 2015 22:44:54 Dan Williams wrote:
> > > On Mon, 2015-08-31 at 21:19 +0200, Ondrej Zary wrote:
> > > > Handle IW_AUTH_ALG_OPEN_SYSTEM in set_auth.
> > > > This allows wpa_supplicant (and thus NetworkManager) to work with
> > > > open APs.
> > > >
> > > > Signed-off-by: Ondrej Zary <[email-masked]>
> > > > ---
> > > >  drivers/net/wireless/airo.c |    7 +++----
> > > >  1 file changed, 3 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/net/wireless/airo.c
> > > > b/drivers/net/wireless/airo.c index d0c97c2..2066a1f 100644
> > > > --- a/drivers/net/wireless/airo.c
> > > > +++ b/drivers/net/wireless/airo.c
> > > > @@ -6670,10 +6670,9 @@ static int airo_set_auth(struct net_device
> > > > *dev, break;
> > > >
> > > >  	case IW_AUTH_80211_AUTH_ALG: {
> > > > -			/* FIXME: What about AUTH_OPEN?  This API seems to
> > > > -			 * disallow setting our auth to AUTH_OPEN.
> > > > -			 */
> > > > -			if (param->value & IW_AUTH_ALG_SHARED_KEY) {
> > > > +			if (param->value & IW_AUTH_ALG_OPEN_SYSTEM) {
> > > > +				local->config.authType = AUTH_OPEN;
> > > > +			} else if (param->value & IW_AUTH_ALG_SHARED_KEY) {
> > > >  				local->config.authType = AUTH_SHAREDKEY;
> > > >  			} else if (param->value & IW_AUTH_ALG_OPEN_SYSTEM) {
> > > >  				local->config.authType = AUTH_ENCRYPT;
> > >
> > > NAK; there are two problems with this patch.  First, there's already an
> > > if test for OPEN_SYSTEM which sets authType to AUTH_ENCRYPT.  Second,
> > > AUTH_OPEN means to disable encryption entirely.  The decision being
> > > made here is whether to use Shared Key or Open authentication, not
> > > whether encryption is being used or not.  Thus this patch would appear
> > > to break most WEP APs?
> > >
> > > Airo really wants to know the auth type *and* whether encryption will
> > > actually be used at the same time, and we don't have that information
> > > here.  I guess the only thing you can do here is call get_wep_key() for
> > > all the indexes and see if any keys are set, and if any keys are set,
> > > use AUTH_ENCRYPT.  If get_wep_key() returns -1 for all 4 indexes, use
> > > AUTH_OPEN.  But you have to make sure that this all gets protected by
> > > local->wep_capable and that you're not checking indexes above
> > > ai->max_wep_idx.  Yay airo!
> >
> > Sorry, I got confused (and it worked with WEP with a test AP, although
> > there's no open system/shared key setting in the firmware).
> >
> > Reading the wpa_supplicant code, it uses IW_AUTH_ALG_OPEN_SYSTEM for WEP
> > open system and also as a default value - which gets used when encryption
> > is disabled:
>
> I think you're still confusing the relationship between Open System and
> WEP in the code and comments here.  802.11 always uses an "auth method"
> regardless of whether encryption is used or not.  There are 3 possible
> settings here:
>
> Auth    Encryption
> ------------------
> OPEN    NONE
> OPEN    WEP
> SHARED  WEP
>
> The problem here is that:
>
> 1) the WEXT SIWAUTH call only sets authentication, but says nothing
> about encryption
>
> 2) that airo is currently structured such that it wants both auth &
> encryption specified at the same time.  It tracks the states in the
> table above with the authType variable, but at the point of SIWAUTH
> there is no information about whether the requested mode is OPEN+NONE or
> OPEN+WEP.
>
> The patches might work for some cases, but they are ignoring others
> where clients might send WEXT calls in different order.  WEXT doesn't
> specify any kind of ordering, which is one reason it's been deprecated
> and replaced with nl80211.  So in your case, the supplicant does [IWAUTH
> + IWENCODE] but that's just how the supplicant decided to implement it.
> If some other client does a perfectly legal [IWENCODE + IWAUTH] then
> your original patch will turn off WEP, when the client wanted OPEN +
> WEP.
>
> > static int wpa_driver_wext_set_auth_alg(void *priv, int auth_alg)
> > {
> >         struct wpa_driver_wext_data *drv = priv;
> >         int algs = 0, res;
> >
> >         if (auth_alg & WPA_AUTH_ALG_OPEN)
> >                 algs |= IW_AUTH_ALG_OPEN_SYSTEM;
> >         if (auth_alg & WPA_AUTH_ALG_SHARED)
> >                 algs |= IW_AUTH_ALG_SHARED_KEY;
> >         if (auth_alg & WPA_AUTH_ALG_LEAP)
> >                 algs |= IW_AUTH_ALG_LEAP;
> >         if (algs == 0) {
> >                 /* at least one algorithm should be set */
> >                 algs = IW_AUTH_ALG_OPEN_SYSTEM;
> >         }
> >
> >         res = wpa_driver_wext_set_auth_param(drv, IW_AUTH_80211_AUTH_ALG,
> >                                              algs);
> >         drv->auth_alg_fallback = res == -2;
> >         return res;
> > }
> >
> >
> > However, when SIOCSIWAUTH fails with EOPNOTSUPP, it tries SIOCSIWENCODE.
> > This patch seems to work too with my AP:
> >
> > diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
> > index d0c97c2..2610fe3 100644
> > --- a/drivers/net/wireless/airo.c
> > +++ b/drivers/net/wireless/airo.c
> > @@ -6670,14 +6670,17 @@ static int airo_set_auth(struct net_device *dev,
> >  		break;
> >
> >  	case IW_AUTH_80211_AUTH_ALG: {
> > -			/* FIXME: What about AUTH_OPEN?  This API seems to
> > -			 * disallow setting our auth to AUTH_OPEN.
> > +			/*
> > +			 * IW_AUTH_ALG_OPEN_SYSTEM is ambiguous here for WEP as
> > +			 * wpa_supplicant uses it for both no encryption and
> > +			 * WEP open system. So we return -EOPNOTSUPP and
> > +			 * wpa_supplicant will use SIOCSIWENCODE instead.
>
> It's not really the supplicant that's ambiguous, the supplicant is doing
> stuff that makes sense.  Unfortunately the WEXT API is what is ambiguous
> here.  Plus, even though wpa_supplicant is the de-facto standard, the
> kernel should treat the supplicant specially and we shouldn't add hacks
> for specific programs.  Let's see if a general solution can be found.
>
> >  			 */
> > -			if (param->value & IW_AUTH_ALG_SHARED_KEY) {
> > +			if (param->value & IW_AUTH_ALG_OPEN_SYSTEM)
> > +				return -EOPNOTSUPP;
>
> While it works due to wpa_supplicant behavior, it's a hack.  It's
> perfectly legal to set OPEN_SYSTEM mode in SIWAUTH.  It's just that airo
> is so simple in how it handles WEXT that it doesn't have enough
> information to do the right thing.  What ipw2200 does is cache values in
> the driver struct so it has everything it needs all the time.
>
> So what I'm saying is that your fix here isn't really a complete fix.  A
> complete fix would work for all these scenarios:
>
> a) SIWAUTH(open), SIWENCODE(enable wep) = WEP + open system
> b) SIWENCODE(enable wep), SIWAUTH(open) = WEP + open system
> c) SIWAUTH(open), SIWENCODE(disable WEP) = unencrypted + open system
> d) SIWENCODE(disable WEP), SIWAUTH(open) = unencrypted + open system
>
> and that complete fix might well be caching the IW_AUTH_ALG value in  a
> couple places (in the SIWAUTH handler and the SIWENCODE and SIWENCODEEXT
> handlers) and also whether WEP is enabled or not, and then using both of
> those values to set authType in SIWAUTH.

Is this enough? It seems to work.

diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index d0c97c2..a8f2767 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -1237,6 +1237,7 @@ struct airo_info {
 
 	int			wep_capable;
 	int			max_wep_idx;
+	int			last_auth;
 
 	/* WPA-related stuff */
 	unsigned int bssListFirst;
@@ -3863,6 +3864,7 @@ static u16 setup_card(struct airo_info *ai, u8 *mac, int lock)
 		}
 		ai->config.opmode = adhoc ? MODE_STA_IBSS : MODE_STA_ESS;
 		ai->config.authType = AUTH_OPEN;
+		ai->last_auth = AUTH_OPEN;
 		ai->config.modulation = MOD_CCK;
 
 		if (le16_to_cpu(cap_rid.len) >= sizeof(cap_rid) &&
@@ -6370,6 +6372,7 @@ static int airo_set_encode(struct net_device *dev,
 		if((index == current_index) && (key.len > 0) &&
 		   (local->config.authType == AUTH_OPEN)) {
 			local->config.authType = AUTH_ENCRYPT;
+			local->last_auth = AUTH_ENCRYPT;
 		}
 	} else {
 		/* Do we want to just set the transmit key index ? */
@@ -6389,12 +6392,16 @@ static int airo_set_encode(struct net_device *dev,
 		}
 	}
 	/* Read the flags */
-	if(dwrq->flags & IW_ENCODE_DISABLED)
+	if (dwrq->flags & IW_ENCODE_DISABLED) {
 		local->config.authType = AUTH_OPEN;	// disable encryption
+		local->last_auth = AUTH_OPEN;
+	}
 	if(dwrq->flags & IW_ENCODE_RESTRICTED)
 		local->config.authType = AUTH_SHAREDKEY;	// Only Both
-	if(dwrq->flags & IW_ENCODE_OPEN)
+	if (dwrq->flags & IW_ENCODE_OPEN) {
 		local->config.authType = AUTH_ENCRYPT;	// Only Wep
+		local->last_auth = AUTH_ENCRYPT;
+	}
 	/* Commit the changes to flags if needed */
 	if (local->config.authType != currentAuthType)
 		set_bit (FLAG_COMMIT, &local->flags);
@@ -6549,12 +6556,16 @@ static int airo_set_encodeext(struct net_device *dev,
 	}
 
 	/* Read the flags */
-	if(encoding->flags & IW_ENCODE_DISABLED)
+	if (encoding->flags & IW_ENCODE_DISABLED) {
 		local->config.authType = AUTH_OPEN;	// disable encryption
+		local->last_auth = AUTH_OPEN;
+	}
 	if(encoding->flags & IW_ENCODE_RESTRICTED)
 		local->config.authType = AUTH_SHAREDKEY;	// Only Both
-	if(encoding->flags & IW_ENCODE_OPEN)
+	if (encoding->flags & IW_ENCODE_OPEN) {
 		local->config.authType = AUTH_ENCRYPT;	// Only Wep
+		local->last_auth = AUTH_ENCRYPT;
+	}
 	/* Commit the changes to flags if needed */
 	if (local->config.authType != currentAuthType)
 		set_bit (FLAG_COMMIT, &local->flags);
@@ -6658,10 +6669,13 @@ static int airo_set_auth(struct net_device *dev,
 	case IW_AUTH_DROP_UNENCRYPTED:
 		if (param->value) {
 			/* Only change auth type if unencrypted */
-			if (currentAuthType == AUTH_OPEN)
+			if (currentAuthType == AUTH_OPEN) {
 				local->config.authType = AUTH_ENCRYPT;
+				local->last_auth = AUTH_ENCRYPT;
+			}
 		} else {
 			local->config.authType = AUTH_OPEN;
+			local->last_auth = AUTH_OPEN;
 		}
 
 		/* Commit the changes to flags if needed */
@@ -6670,13 +6684,14 @@ static int airo_set_auth(struct net_device *dev,
 		break;
 
 	case IW_AUTH_80211_AUTH_ALG: {
-			/* FIXME: What about AUTH_OPEN?  This API seems to
-			 * disallow setting our auth to AUTH_OPEN.
-			 */
 			if (param->value & IW_AUTH_ALG_SHARED_KEY) {
 				local->config.authType = AUTH_SHAREDKEY;
 			} else if (param->value & IW_AUTH_ALG_OPEN_SYSTEM) {
-				local->config.authType = AUTH_ENCRYPT;
+				/* We don't know here if WEP open system or
+				 * unencrypted mode was requested - so use the
+				 * last mode (of these two) used last time
+				 */
+				local->config.authType = local->last_auth;
 			} else
 				return -EINVAL;

-- 
Ondrej Zary