linux-kernel - Re: Issue with iwd + Linux 5.8.3 + WPA Enterprise

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Message-ID: <4bb6d926-a249-8183-b3d9-05b8e1b7808a@gmail.com>
Date:   Wed, 26 Aug 2020 10:25:48 -0500
From:   Denis Kenzior <denkenz@...il.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Andrew Zaborowski <andrew.zaborowski@...el.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Paul Menzel <pmenzel@...gen.mpg.de>,
        Caleb Jorden <caljorden@...mail.com>,
        Sasha Levin <sashal@...nel.org>, iwd@...ts.01.org,
        "# 3.4.x" <stable@...r.kernel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: Issue with iwd + Linux 5.8.3 + WPA Enterprise

Hi Herbert,

On 8/26/20 9:19 AM, Herbert Xu wrote:
> On Wed, Aug 26, 2020 at 08:57:17AM -0500, Denis Kenzior wrote:
>>
>> I'm just waking up now, so I might seem dense, but for my education, can you
>> tell me why we need to set MSG_MORE when we issue just a single sendmsg
>> followed immediately by recv/recvmsg? ell/iwd operates on small buffers, so
>> we don't really feed the kernel data in multiple send operations.  You can
>> see this in the ell git tree link referenced in Andrew's reply.
> 
> You obviously don't need MSG_MORE if you're doing a single sendmsg.
> 
> The problematic code is in l_cipher_set_iv.  It does a sendmsg(2)
> that expects to be followed by more sendmsg(2) calls before a
> recvmsg(2).  That's the one that needs a MSG_MORE.
> 

Gotcha.  I fixed the set_iv part now in ell:
https://git.kernel.org/pub/scm/libs/ell/ell.git/commit/?id=87c76bbc85fe286925cbdb53d733fc9f9fd2ed12

Regards,
-Denis