netdev - Re: [PATCH v3 2/4] wifi: libertas: only add RSN/WPA IE in lbs_add_wpa

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Date:   Tue, 17 Jan 2023 22:35:56 -0800
From:   Doug Brown <doug@...morgal.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Dan Williams <dcbw@...hat.com>,
        libertas-dev@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v3 2/4] wifi: libertas: only add RSN/WPA IE in
 lbs_add_wpa_tlv

On 1/17/2023 12:59 AM, Simon Horman wrote:
> On Mon, Jan 16, 2023 at 12:21:24PM -0800, Doug Brown wrote:
>> [You don't often get email from doug@...morgal.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>>
>> The existing code only converts the first IE to a TLV, but it returns a
>> value that takes the length of all IEs into account. When there is more
>> than one IE (which happens with modern wpa_supplicant versions for
>> example), the returned length is too long and extra junk TLVs get sent
>> to the firmware, resulting in an association failure.
>>
>> Fix this by finding the first RSN or WPA IE and only adding that. This
>> has the extra benefit of working properly if the RSN/WPA IE isn't the
>> first one in the IE buffer.
>>
>> While we're at it, clean up the code to use the available structs like
>> the other lbs_add_* functions instead of directly manipulating the TLV
>> buffer.
>>
>> Signed-off-by: Doug Brown <doug@...morgal.com>
>> ---
>>   drivers/net/wireless/marvell/libertas/cfg.c | 28 +++++++++++++--------
>>   1 file changed, 18 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/net/wireless/marvell/libertas/cfg.c b/drivers/net/wireless/marvell/libertas/cfg.c
>> index 3e065cbb0af9..3f35dc7a1d7d 100644
>> --- a/drivers/net/wireless/marvell/libertas/cfg.c
>> +++ b/drivers/net/wireless/marvell/libertas/cfg.c
> 
> ...
> 
>> @@ -428,14 +438,12 @@ static int lbs_add_wpa_tlv(u8 *tlv, const u8 *ie, u8 ie_len)
>>           *   __le16  len
>>           *   u8[]    data
>>           */
>> -       *tlv++ = *ie++;
>> -       *tlv++ = 0;
>> -       tlv_len = *tlv++ = *ie++;
>> -       *tlv++ = 0;
>> -       while (tlv_len--)
>> -               *tlv++ = *ie++;
>> -       /* the TLV is two bytes larger than the IE */
>> -       return ie_len + 2;
>> +       wpatlv->header.type = cpu_to_le16(wpaie->id);
>> +       wpatlv->header.len = cpu_to_le16(wpaie->datalen);
>> +       memcpy(wpatlv->data, wpaie->data, wpaie->datalen);
> 
> Hi Doug,
> 
> Thanks for fixing the endiness issues with cpu_to_le16()
> This part looks good to me now. Likewise for patch 4/4.
> 
> One suggestion I have, which is probably taking things to far,
> is a helper for what seems to be repeated code-pattern.
> But I don't feel strongly about that.

Thanks Simon. Is this basically what you're suggesting for a helper?

static int lbs_add_ie_tlv(u8 *tlvbuf, const struct element *ie, u16 tlvtype)
{
	struct mrvl_ie_data *tlv = (struct mrvl_ie_data *)tlvbuf;
	tlv->header.type = cpu_to_le16(tlvtype);
	tlv->header.len = cpu_to_le16(ie->datalen);
	memcpy(tlv->data, ie->data, ie->datalen);
	return sizeof(struct mrvl_ie_header) + ie->datalen;
}

And then in the two functions where I'm doing that, at the bottom:

return lbs_add_ie_tlv(tlv, wpaie, wpaie->id);
return lbs_add_ie_tlv(tlv, wpsie, TLV_TYPE_WPS_ENROLLEE);

I could definitely do that to avoid repeating the chunk of code that
fills out the struct in the two functions. A lot of the other
lbs_add_*_tlv functions follow a similar pattern of setting up a struct
pointer and filling out the header, so I don't think it's too crazy to
just repeat the code twice. On the other hand, the example above does
look pretty darn clean. I don't feel strongly either way myself.

> 
>> +
>> +       /* Return the total number of bytes added to the TLV buffer */
>> +       return sizeof(struct mrvl_ie_header) + wpaie->datalen;
>>   }
>>
>>   /*
>> --
>> 2.34.1
>>