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

[Gaston Gonzalez <gascoar@gmail.com>]

On 08/05/15 08:03, Dan Carpenter wrote:
> To be honest, I'm a little bit a newbie myself when it comes to
> linux-wireless so keep that in mind.  ;)  Changing the parameters seems
> simple enough.  But it needs to an EXPORT_SYMBOL() and to be declared in
> a header file and I'm not sure what else.  But we have four
> implementations of this function now.
Ok Dan, I did the test exporting tkip_mixing_phase2(). Below is how the
patch would look.
So far I didn't get any warnings.

Summary and comments:

 - Goal: use tkip_mixing_phase2() from /net/mac80211/tkip.c in
drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c

 - Approach: export  tkip_mixing_phase2(), adding tkip_ctx structure
definition without toucing original structures from
ieee80211_crypt_tkip.c. As you pointed out, this is done by adding
EXPORT_SYMBOL() and declaring the function in the destined file.

 - As commented in the previous email, adding tkip_ctx structure
duplicates some members. Only one of them is used in the function: p1k,
so it is copied from one structure to the other.

 - Please let me know if the implementation is useful or is better
another approach or if it needs changes.

 - In the case this is well oriented, the submission form would be a new
patch or v2 of the original one?

regards,

Gaston


---
 .../rtl8192u/ieee80211/ieee80211_crypt_tkip.c      | 79
++++++++--------------
 net/mac80211/tkip.c                                |  3 +-
 2 files changed, 32 insertions(+), 50 deletions(-)

diff --git a/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
b/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
index 1f80c52..51e2034 100644
--- a/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
+++ b/drivers/staging/rtl8192u/ieee80211/ieee80211_crypt_tkip.c
@@ -18,3 +18,4 @@
 #include <linux/if_ether.h>
 #include <linux/if_arp.h>
 #include <linux/string.h>
+#include <net/mac80211.h>

 #include "ieee80211.h"

@@ -61,2 +62,2 @@ struct ieee80211_tkip_data {
     u8 rx_hdr[16], tx_hdr[16];
 };

+enum ieee80211_internal_tkip_state {
+    TKIP_STATE_NOT_INIT,
+    TKIP_STATE_PHASE1_DONE,
+    TKIP_STATE_PHASE1_HW_UPLOADED,
+};
+
+struct tkip_ctx {
+    u32 iv32;    /* current iv32 */
+    u16 iv16;    /* current iv16 */
+    u16 p1k[5];    /* p1k cache */
+    u32 p1k_iv32;    /* iv32 for which p1k computed */
+    enum ieee80211_internal_tkip_state state;
+};
+
+void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
+            u16 tsc_IV16, u8 *rc4key);
+
 static void *ieee80211_tkip_init(int key_idx)
 {
     struct ieee80211_tkip_data *priv;
@@ -254,1 +272,1 @@ static void tkip_mixing_phase1(u16 *TTAK, const u8
*TK, const u8 *TA, u32 IV32)
 }


-static void tkip_mixing_phase2(u8 *WEPSeed, const u8 *TK, const u16 *TTAK,
-                   u16 IV16)
-{
-    /* Make temporary area overlap WEP seed so that the final copy can be
-     * avoided on little endian hosts. */
-    u16 *PPK = (u16 *) &WEPSeed[4];
-
-    /* Step 1 - make copy of TTAK and bring in TSC */
-    PPK[0] = TTAK[0];
-    PPK[1] = TTAK[1];
-    PPK[2] = TTAK[2];
-    PPK[3] = TTAK[3];
-    PPK[4] = TTAK[4];
-    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[2] += RotR1(PPK[1]);
-    PPK[3] += RotR1(PPK[2]);
-    PPK[4] += RotR1(PPK[3]);
-    PPK[5] += RotR1(PPK[4]);
-
-    /* Step 3 - bring in last of TK bits, assign 24-bit WEP IV value
-     * WEPSeed[0..2] is transmitted as WEP IV */
-    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);
-
-#ifdef __BIG_ENDIAN
-    {
-        int i;
-        for (i = 0; i < 6; i++)
-            PPK[i] = (PPK[i] << 8) | (PPK[i] >> 8);
-    }
-#endif
-}
-
-
 static int ieee80211_tkip_encrypt(struct sk_buff *skb, int hdr_len,
void *priv)
 {
     struct ieee80211_tkip_data *tkey = priv;
         int len;
     u8 *pos;
+    struct tkip_ctx *tx = NULL;
+    size_t p1k_len;
     struct rtl_80211_hdr_4addr *hdr;
     cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
     struct blkcipher_desc desc = {.tfm = tkey->tx_tfm_arc4};
@@ -314,2 +287,2 @@ static int ieee80211_tkip_encrypt(struct sk_buff
*skb, int hdr_len, void *priv)
     u32 crc;
     struct scatterlist sg;

+    p1k_len = sizeof(tkey->tx_ttak);
+    memcpy(&tx->p1k, &tkey->tx_ttak, p1k_len);
+
     if (skb_headroom(skb) < 8 || skb_tailroom(skb) < 4 ||
         skb->len < hdr_len)
         return -1;
@@ -327,7 +303,7 @@ static int ieee80211_tkip_encrypt(struct sk_buff
*skb, int hdr_len, void *priv)
                     tkey->tx_iv32);
             tkey->tx_phase1_done = 1;
         }
-        tkip_mixing_phase2(rc4key, tkey->key, tkey->tx_ttak,
tkey->tx_iv16);
+        tkip_mixing_phase2(tkey->key, tx, tkey->tx_iv16, rc4key);
     }
     else
     tkey->tx_phase1_done = 1;
@@ -387,6 +363,8 @@ static int ieee80211_tkip_encrypt(struct sk_buff
*skb, int hdr_len, void *priv)
 static int ieee80211_tkip_decrypt(struct sk_buff *skb, int hdr_len,
void *priv)
 {
     struct ieee80211_tkip_data *tkey = priv;
+    struct tkip_ctx *rx = NULL;
+    size_t p1k_len;
     u8 keyidx, *pos;
     u32 iv32;
     u16 iv16;
@@ -401,2 +379,2 @@ static int ieee80211_tkip_decrypt(struct sk_buff
*skb, int hdr_len, void *priv)
     if (skb->len < hdr_len + 8 + 4)
         return -1;

+    p1k_len = sizeof(tkey->rx_ttak);
+    memcpy(&rx->p1k, &tkey->rx_ttak, p1k_len);
+
     hdr = (struct rtl_80211_hdr_4addr *) skb->data;
     pos = skb->data + hdr_len;
     keyidx = pos[3];
@@ -447,4 +428,4 @@ static int ieee80211_tkip_decrypt(struct sk_buff
*skb, int hdr_len, void *priv)
             tkip_mixing_phase1(tkey->rx_ttak, tkey->key, hdr->addr2, iv32);
             tkey->rx_phase1_done = 1;
         }
-        tkip_mixing_phase2(rc4key, tkey->key, tkey->rx_ttak, iv16);
+        tkip_mixing_phase2(tkey->key, rx, tkey->rx_iv16, rc4key);

         plen = skb->len - hdr_len - 12;

diff --git a/net/mac80211/tkip.c b/net/mac80211/tkip.c
index 0ae2077..1f74866 100644
--- a/net/mac80211/tkip.c
+++ b/net/mac80211/tkip.c
@@ -105,2 +105,2 @@ static void tkip_mixing_phase1(const u8 *tk, struct
tkip_ctx *ctx,
     ctx->p1k_iv32 = tsc_IV32;
 }

-static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
+void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
                    u16 tsc_IV16, u8 *rc4key)
 {
     u16 ppk[6];
@@ -138,3 +138,4 @@ static void tkip_mixing_phase2(const u8 *tk, struct
tkip_ctx *ctx,
     for (i = 0; i < 6; i++)
         put_unaligned_le16(ppk[i], rc4key + 2 * i);
 }
+EXPORT_SYMBOL(tkip_mixing_phase2);

 /* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first
octets
  * of the IV. Returns pointer to the octet following IVs (i.e.,
beginning of
--
2.1.4