Re: [PATCH] cfg80211: fix a couple of bugs with key ioctls

Johannes Berg
2009-05-13T09:05:16Z

Hi!

Thanks for the extensive debugging!

On Wed, 2009-05-13 at 04:56 +0100, Hin-Tak Leung wrote:
> Hiya, I stuck in a few printk(KERN_DEBUG __LINE__) around the new
> -EINVAL's and tried to see why setting things by iwconfig manually
> works, but NM/wpa_supplicant does not, and here is what I found.
> Around line 600 of net/wireless/wext-compat.c (this is the hackish mod
> version):
> ------------------------------------------
> int cfg80211_wext_siwencodeext(struct net_device *dev,
> struct iw_request_info *info,
> struct iw_point *erq, char *extra)
>
> switch (ext->alg) {
>
> case IW_ENCODE_ALG_WEP:
> if (erq->length == 5)
> cipher = WLAN_CIPHER_SUITE_WEP40;
> else if (erq->length == 13)
> cipher = WLAN_CIPHER_SUITE_WEP104;
> else {
> printk(KERN_DEBUG "line %d %d\n", __LINE__, erq->length);
> cipher = WLAN_CIPHER_SUITE_WEP104;
> /* return -EINVAL; */
> }
> break;
> }

Ok, so iwencodeext is used, presumably by wpa_supplicant because NM
never uses that ioctl, at least not as far as I can tell.

> ------------------------------------------------
> For some unknown reason, when run with NM/wpa_supplicant with the same
> authentication credentials to the same AP, erq->length is 53 instead
> of 13.

That's strange. Do you know which wpa_supplicant version and NM you are
using? Is it always 53, or could it be random?

> If I just modify it as above instead of returning EINVAL, then
> I get to authenticate, etc. in the old mac80211 ioctls, the decision
> of cipher is postponed a lot later, after playing with the default key
> a bit?
>
> Anyway, I think 53 is either 40+13 or 13 *4 +1, so is it a case of
> wpa_supplicant putting more stuff at the end or an offset somewhere?

No, that's sizeof(struct iw_encode_ext) and now I'm confused as to why
this actually worked for me. Ok, I see now I think, can you try this
patch?

johannes

--- wireless-testing.orig/net/wireless/wext-compat.c 2009-05-13 11:03:12.000000000 +0200
+++ wireless-testing/net/wireless/wext-compat.c 2009-05-13 11:03:35.000000000 +0200
@@ -614,9 +614,9 @@ int cfg80211_wext_siwencodeext(struct ne
cipher = 0;
break;
case IW_ENCODE_ALG_WEP:
- if (erq->length == 5)
+ if (ext->key_len == 5)
cipher = WLAN_CIPHER_SUITE_WEP40;
- else if (erq->length == 13)
+ else if (ext->key_len == 13)
cipher = WLAN_CIPHER_SUITE_WEP104;
else
return -EINVAL;