[PATCH] staging: rtl8192u: ieee80211: Silence sparse warning

[PATCH] staging: rtl8192u: ieee80211: Silence sparse warning

[Gaston Gonzalez]

Silence the following sparse warning:

drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c:184:16: warning: cast to restricted __le16

Signed-off-by: Gaston Gonzalez <gascoar@gmail.com>
---
 .../rtl8192u/ieee80211/ieee80211_crypt_tkip.c      | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c b/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
index e815c81..efa6983 100644
--- a/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
+++ b/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
@@ -179,1 +179,1 @@ static inline u16 Mk16(u8 hi, u8 lo)
 }


-static inline u16 Mk16_le(u16 *v)
+static inline u16 Mk16_le(__le16 *v)
 {
 	return le16_to_cpu(*v);
 }
@@ -270,1 +270,1 @@ static void tkip_mixing_phase2(u8 *WEPSeed, const u8 *TK, const u16 *TTAK,
 	PPK[5] = TTAK[4] + IV16;

 	/* Step 2 - 96-bit bijective mixing using S-box */
-	PPK[0] += _S_(PPK[5] ^ Mk16_le((u16 *) &TK[0]));
-	PPK[1] += _S_(PPK[0] ^ Mk16_le((u16 *) &TK[2]));
-	PPK[2] += _S_(PPK[1] ^ Mk16_le((u16 *) &TK[4]));
-	PPK[3] += _S_(PPK[2] ^ Mk16_le((u16 *) &TK[6]));
-	PPK[4] += _S_(PPK[3] ^ Mk16_le((u16 *) &TK[8]));
-	PPK[5] += _S_(PPK[4] ^ Mk16_le((u16 *) &TK[10]));
-
-	PPK[0] += RotR1(PPK[5] ^ Mk16_le((u16 *) &TK[12]));
-	PPK[1] += RotR1(PPK[0] ^ Mk16_le((u16 *) &TK[14]));
+	PPK[0] += _S_(PPK[5] ^ Mk16_le((__le16 *) &TK[0]));
+	PPK[1] += _S_(PPK[0] ^ Mk16_le((__le16 *) &TK[2]));
+	PPK[2] += _S_(PPK[1] ^ Mk16_le((__le16 *) &TK[4]));
+	PPK[3] += _S_(PPK[2] ^ Mk16_le((__le16 *) &TK[6]));
+	PPK[4] += _S_(PPK[3] ^ Mk16_le((__le16 *) &TK[8]));
+	PPK[5] += _S_(PPK[4] ^ Mk16_le((__le16 *) &TK[10]));
+
+	PPK[0] += RotR1(PPK[5] ^ Mk16_le((__le16 *) &TK[12]));
+	PPK[1] += RotR1(PPK[0] ^ Mk16_le((__le16 *) &TK[14]));
 	PPK[2] += RotR1(PPK[1]);
 	PPK[3] += RotR1(PPK[2]);
 	PPK[4] += RotR1(PPK[3]);
@@ -289,4 +289,4 @@ static void tkip_mixing_phase2(u8 *WEPSeed, const u8 *TK, const u16 *TTAK,
 	WEPSeed[0] = Hi8(IV16);
 	WEPSeed[1] = (Hi8(IV16) | 0x20) & 0x7F;
 	WEPSeed[2] = Lo8(IV16);
-	WEPSeed[3] = Lo8((PPK[5] ^ Mk16_le((u16 *) &TK[0])) >> 1);
+	WEPSeed[3] = Lo8((PPK[5] ^ Mk16_le((__le16 *) &TK[0])) >> 1);

 #ifdef __BIG_ENDIAN
 	{
--
2.1.4

Re: [PATCH] staging: rtl8192u: ieee80211: Silence sparse warning

[Dan Carpenter]

On Sun, Apr 19, 2015 at 05:43:51PM -0300, Gaston Gonzalez wrote:
> Silence the following sparse warning:
> 
> drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c:184:16: warning: cast to restricted __le16
> 

We have a tkip_mixing_phase2() function in net/mac80211/tkip.c.  That's
probably the better thing.

> Signed-off-by: Gaston Gonzalez <gascoar@gmail.com>
> ---
>  .../rtl8192u/ieee80211/ieee80211_crypt_tkip.c      | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c b/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
> index e815c81..efa6983 100644
> --- a/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
> +++ b/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
> @@ -179,1 +179,1 @@ static inline u16 Mk16(u8 hi, u8 lo)
>  }
> 
> 
> -static inline u16 Mk16_le(u16 *v)
> +static inline u16 Mk16_le(__le16 *v)
>  {
>  	return le16_to_cpu(*v);
>  }


Mk16_le() is a bad function name and as we can see from tkip.c it just
duplicates get_unaligned_le16().  Better to make TK void pointer instead
of a u8 pointer (because it doesn't point to u8s so we have to cast it
every time we use it).  This is another trick I learned from tkip.c.

regards,
dan carpenter

Re: [PATCH] staging: rtl8192u: ieee80211: Silence sparse warning

[Gaston Gonzalez]

On 20/04/15 05:24, Dan Carpenter wrote:
> Mk16_le() is a bad function name and as we can see from tkip.c it just
> duplicates get_unaligned_le16().  Better to make TK void pointer instead
> of a u8 pointer (because it doesn't point to u8s so we have to cast it
> every time we use it).  This is another trick I learned from tkip.c.
Ok. Could I just remove Mk16_le() and use get_unaligned_le16() instead?

I built rtl8192u/ using get_unaligned_le16() for the following lines and
I didn't get any warning:

+#include <asm/unaligned.h>

-    PPK[0] += _S_(PPK[5] ^ Mk16_le((u16 *) &TK[0]));
-    PPK[0] += _S_(PPK[5] ^ Mk16_le((u16 *) &TK[0]));
-    PPK[1] += _S_(PPK[0] ^ Mk16_le((u16 *) &TK[2]));
-    PPK[2] += _S_(PPK[1] ^ Mk16_le((u16 *) &TK[4]));
-    PPK[3] += _S_(PPK[2] ^ Mk16_le((u16 *) &TK[6]));
-    PPK[4] += _S_(PPK[3] ^ Mk16_le((u16 *) &TK[8]));
-    PPK[5] += _S_(PPK[4] ^ Mk16_le((u16 *) &TK[10]));
-
-    PPK[0] += RotR1(PPK[5] ^ Mk16_le((u16 *) &TK[12]));
-    PPK[1] += RotR1(PPK[0] ^ Mk16_le((u16 *) &TK[14]));
+    PPK[0] += _S_(PPK[5] ^ get_unaligned_le16(TK + 0));
+    PPK[1] += _S_(PPK[0] ^ get_unaligned_le16(TK + 2));
+    PPK[2] += _S_(PPK[1] ^ get_unaligned_le16(TK + 4));
+    PPK[3] += _S_(PPK[2] ^ get_unaligned_le16(TK + 6));
+    PPK[4] += _S_(PPK[3] ^ get_unaligned_le16(TK + 8));
+    PPK[5] += _S_(PPK[4] ^ get_unaligned_le16(TK + 10));
+
+    PPK[0] += RotR1(PPK[5] ^ get_unaligned_le16(TK + 12));
+    PPK[1] += RotR1(PPK[0] ^ get_unaligned_le16(TK + 14));

Re: [PATCH] staging: rtl8192u: ieee80211: Silence sparse warning

[Dan Carpenter]

Can't we just export the tkip.c function?

regards,
dan carpenter

Re: [PATCH] staging: rtl8192u: ieee80211: Silence sparse warning

[Gaston Gonzalez]

On 27/04/15 07:12, Dan Carpenter wrote:
> Can't we just export the tkip.c function?
>
> regards,
> dan carpenter
>
Hi Dan,

(sorry for the delayed response)

The inputs of the two implementations of tkip_mixing_phase2() differ in
one parameter:

 - ieee80211_crypt_tkip.c expects 'const u16 *TTAK'
 - tkip.c expects 'struct tkip_ctx *ctx'

tkip_mixing_phase2() is called two times in ieee80211_crypt_tkip.c:

git grep tkip_mixing_phase2  drivers/staging/rtl8192u/ieee80211/

drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c:static void
tkip_mixing_phase2(u8 *WEPSeed, const u8 *TK, const u16 *TTAK,

drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c:             
tkip_mixing_phase2(rc4key, tkey->key, tkey->tx_ttak, tkey->tx_iv16);

drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c:             
tkip_mixing_phase2(rc4key, tkey->key, tkey->rx_ttak, iv16);


tkey is a 'struct ieee80211_tkip_data', which differs from tkip_ctx
structure. So in the case of exporting the tkip.c function, we would
need to add 'struct tkip_ctx' definition, and not just change the
function input definition.

The only member of tkip_ctx structure used in tkip_mixing_phase2() is
p1k, which is the equivalent of TTAK array in ieee80211_crypt_tkip.c .
Thus - I'm new to this so I may be missing something - one way would be
to just add the tkip_ctx structure definition in ieee80211_crypt_tkip.c.
The down side of doing this is that there would be some parameters
defined twice in two different structures: u32 iv32, u16 iv16, u16
p1k[5], u32 p1k_iv32

Another way would be split ieee80211_tkip_data structure in struct
tkip_ctx on one side, and leave the rest of the members on the original
structure. This would avoid to duplicate the members definitions, but I
guess that approach could broke other things...

As I said, I'm new to this so I may be missing something, maybe a
different approach?

One detail: although not used in the function, 'enum
ieee80211_internal_tkip_state state' is not defined in 'struct
ieee80211_tkip_data', thus in any case that definition would have to be
added.

regards,

Gaston