crypto: stm32/cryp - add weak key check for DES

Add weak key test for des functions calling the generic
des_ekey.
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/stm32/Kconfig

@@ -24,6 +24,7 @@ config CRYPTO_DEV_STM32_CRYP
 	depends on ARCH_STM32
 	select CRYPTO_HASH
 	select CRYPTO_ENGINE
+	select CRYPTO_DES
 	help
           This enables support for the CRYP (AES/DES/TDES) hw accelerator which
 	  can be found on STMicroelectronics STM32 SOC.

drivers/crypto/stm32/stm32-cryp.c

@@ -753,9 +753,18 @@ static int stm32_cryp_aes_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
 static int stm32_cryp_des_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
 				 unsigned int keylen)
 {
+	u32 tmp[DES_EXPKEY_WORDS];
+
 	if (keylen != DES_KEY_SIZE)
 		return -EINVAL;
-	else
+
+	if ((crypto_ablkcipher_get_flags(tfm) &
+	     CRYPTO_TFM_REQ_FORBID_WEAK_KEYS) &&
+	    unlikely(!des_ekey(tmp, key))) {
+		crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_RES_WEAK_KEY);
+		return -EINVAL;
+	}
+
 	return stm32_cryp_setkey(tfm, key, keylen);
 }