linux-kernel - Re: [PATCH] staging:r8188eu: Use lib80211 to encrypt (WEP) tx frames

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Message-ID: <20180604091139.zbe2kkoe3uaktanu@mwanda>
Date:   Mon, 4 Jun 2018 12:11:39 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Ivan Safonov <insafonov@...il.com>
Cc:     devel@...verdev.osuosl.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Janani Sankara Babu <jananis37@...il.com>,
        linux-kernel@...r.kernel.org,
        Santha Meena Ramamoorthy <santhameena13@...il.com>
Subject: Re: [PATCH] staging:r8188eu: Use lib80211 to encrypt (WEP) tx frames

On Sun, Jun 03, 2018 at 07:16:19PM +0300, Ivan Safonov wrote:
> On 05/28/2018 04:53 PM, Dan Carpenter wrote:
> > On Mon, May 28, 2018 at 09:18:21AM +0300, Ivan Safonov wrote:
> > > Put data to skb, decrypt with lib80211_crypt_wep, and place back to tx buffer.
> > > 
> > > Signed-off-by: Ivan Safonov <insafonov@...il.com>
> > > ---
> > >   drivers/staging/rtl8188eu/core/rtw_security.c | 72 ++++++++++++++++-----------
> > >   1 file changed, 43 insertions(+), 29 deletions(-)
> > > 
> > > diff --git a/drivers/staging/rtl8188eu/core/rtw_security.c b/drivers/staging/rtl8188eu/core/rtw_security.c
> > > index bfe0b217e679..80d7569a3108 100644
> > > --- a/drivers/staging/rtl8188eu/core/rtw_security.c
> > > +++ b/drivers/staging/rtl8188eu/core/rtw_security.c
> > > @@ -139,17 +139,11 @@ static __le32 getcrc32(u8 *buf, int len)
> > >   	Need to consider the fragment  situation
> > >   */
> > >   void rtw_wep_encrypt(struct adapter *padapter, u8 *pxmitframe)
> > > -{	/*  exclude ICV */
> > > -
> > > -	unsigned char	crc[4];
> > > -	struct arc4context	 mycontext;
> > > -
> > > +{
> > >   	int	curfragnum, length;
> > > -	u32	keylength;
> > > -	u8	*pframe, *payload, *iv;    /* wepkey */
> > > -	u8	wepkey[16];
> > > -	u8   hw_hdr_offset = 0;
> > > +	u8 *pframe;
> > > +	u8 hw_hdr_offset = 0;
> > >   	struct	pkt_attrib	 *pattrib = &((struct xmit_frame *)pxmitframe)->attrib;
> > >   	struct	security_priv	*psecuritypriv = &padapter->securitypriv;
> > >   	struct	xmit_priv		*pxmitpriv = &padapter->xmitpriv;
> > > @@ -165,33 +159,53 @@ void rtw_wep_encrypt(struct adapter *padapter, u8 *pxmitframe)
> > >   	/* start to encrypt each fragment */
> > >   	if ((pattrib->encrypt == _WEP40_) || (pattrib->encrypt == _WEP104_)) {
> > > -		keylength = psecuritypriv->dot11DefKeylen[psecuritypriv->dot11PrivacyKeyIndex];
> > > +		const int keyindex = psecuritypriv->dot11PrivacyKeyIndex;
> > > +		void *crypto_private;
> > > +		struct sk_buff *skb;
> > > +		struct lib80211_crypto_ops *crypto_ops = try_then_request_module(lib80211_get_crypto_ops("WEP"), "lib80211_crypt_wep");
> > > +
> > > +		if (!crypto_ops)
> > > +			goto exit;
> > > +
> > > +		crypto_private = crypto_ops->init(keyindex);
> > > +		if (!crypto_private)
> > > +			goto exit;
> > > +
> > > +		if (crypto_ops->set_key(psecuritypriv->dot11DefKey[keyindex].skey,
> > > +					psecuritypriv->dot11DefKeylen[keyindex], NULL, crypto_private) < 0)
> > > +			goto exit;
> > >   		for (curfragnum = 0; curfragnum < pattrib->nr_frags; curfragnum++) {
> > > -			iv = pframe+pattrib->hdrlen;
> > > -			memcpy(&wepkey[0], iv, 3);
> > > -			memcpy(&wepkey[3], &psecuritypriv->dot11DefKey[psecuritypriv->dot11PrivacyKeyIndex].skey[0], keylength);
> > > -			payload = pframe+pattrib->iv_len+pattrib->hdrlen;
> > > +			if (curfragnum + 1 == pattrib->nr_frags)
> > > +				length = pattrib->last_txcmdsz;
> > > +			else
> > > +				length = pxmitpriv->frag_len;
> > > +			skb = dev_alloc_skb(length);
> > > +			if (!skb)
> > > +				goto exit;
> > > -			if ((curfragnum+1) == pattrib->nr_frags) {	/* the last fragment */
> > > -				length = pattrib->last_txcmdsz-pattrib->hdrlen-pattrib->iv_len-pattrib->icv_len;
> > > +			skb_put_data(skb, pframe, length);
> > > -				*((__le32 *)crc) = getcrc32(payload, length);
> > > +			memmove(skb->data + 4, skb->data, pattrib->hdrlen);
> > > +			skb_pull(skb, 4);
> > > +			skb_trim(skb, skb->len - 4);
> > > -				arcfour_init(&mycontext, wepkey, 3+keylength);
> > > -				arcfour_encrypt(&mycontext, payload, payload, length);
> > > -				arcfour_encrypt(&mycontext, payload+length, crc, 4);
> > > -			} else {
> > > -				length = pxmitpriv->frag_len-pattrib->hdrlen-pattrib->iv_len-pattrib->icv_len;
> > > -				*((__le32 *)crc) = getcrc32(payload, length);
> > > -				arcfour_init(&mycontext, wepkey, 3+keylength);
> > > -				arcfour_encrypt(&mycontext, payload, payload, length);
> > > -				arcfour_encrypt(&mycontext, payload+length, crc, 4);
> > > -
> > > -				pframe += pxmitpriv->frag_len;
> > > -				pframe = (u8 *)round_up((size_t)(pframe), 4);
> > > +			if (crypto_ops->encrypt_mpdu(skb, pattrib->hdrlen, crypto_private)) {
> > > +				kfree_skb(skb);
> > > +				goto exit;
> > >   			}
> > > +
> > > +			memcpy(pframe, skb->data, skb->len);
> > > +
> > > +			pframe += skb->len;
> > > +			pframe = (u8 *)round_up((size_t)(pframe), 4);
> > > +
> > > +			kfree_skb(skb);
> > >   		}
> > > +
> > > +exit:
> > > +		if (crypto_ops && crypto_private)
> > > +			crypto_ops->deinit(crypto_private);
> > 
> > One label style error handling is always bugggy.  I'm surprised GCC
> > doesn't catch that crypto_private can be uninitialized...
> 
> This is not a compiler defect. The code
> 
> if (a && b) {
> 	...
> }
> 
> is equal to
> 
> if (a) {
> 	if (b) {
> 		...
> 	}
> }

Heh...  Oops.  Sorry, I misread the code.  That's embarrassing.

> rtw_(wep|aes|tkip)_(en|de)crypt still need to be rewritten, so I'll leave
> this patch as is. In the following patches I'll take your comments into
> account, they really simplify reading the code.
> 

Sounds good.

regards,
dan carpenter