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

[Ivan Safonov <insafonov@xxxxxxxxx>]

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@xxxxxxxxx>
> > ---
> >   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) {
		...
	}
}

> Flip the if ((pattrib->encrypt == _WEP40_) || (pattrib->encrypt == _WEP104_)) {
> tests so it's:
>
> 	if (pattrib->encrypt != _WEP40_ && pattrib->encrypt != _WEP104_)
> 		return;

The check is superfluous inside this function, it should be
(somewhen) around rtw_wep_encrypt().

> The use normal error handling style:
>
> 	kfree_skb(skb);
> 	return;
>
> err_free_skb:
> 	kfree_skb(skb);
> err_deinit:
> 	crypto_ops->deinit(crypto_private);
> }

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.

> regards,
> dan carpenter

Ivan Safonov.
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