smb: Use arc4 library instead of duplicate arc4 code

fs/smb/common/cifs_arc4.c has an implementation of ARC4, but a copy of
this same code is also present in lib/crypto/arc4.c to serve the other
users of this legacy algorithm in the kernel.  Remove the duplicate
implementation in fs/smb/, which seems to have been added because of a
misunderstanding, and just use the lib/crypto/ one.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: Eric Biggers

fs/smb/client/Kconfig

@@ -15,6 +15,7 @@ config CIFS
 	select CRYPTO_GCM
 	select CRYPTO_ECB
 	select CRYPTO_AES
+	select CRYPTO_LIB_ARC4
 	select KEYS
 	select DNS_RESOLVER
 	select ASN1

fs/smb/client/cifsencrypt.c

@@ -22,8 +22,8 @@
 #include <linux/highmem.h>
 #include <linux/fips.h>
 #include <linux/iov_iter.h>
-#include "../common/arc4.h"
 #include <crypto/aead.h>
+#include <crypto/arc4.h>
 
 static size_t cifs_shash_step(void *iter_base, size_t progress, size_t len,
 			      void *priv, void *priv2)
@@ -725,9 +725,9 @@ calc_seckey(struct cifs_ses *ses)
 		return -ENOMEM;
 	}
 
-	cifs_arc4_setkey(ctx_arc4, ses->auth_key.response, CIFS_SESS_KEY_SIZE);
-	cifs_arc4_crypt(ctx_arc4, ses->ntlmssp->ciphertext, sec_key,
-			CIFS_CPHTXT_SIZE);
+	arc4_setkey(ctx_arc4, ses->auth_key.response, CIFS_SESS_KEY_SIZE);
+	arc4_crypt(ctx_arc4, ses->ntlmssp->ciphertext, sec_key,
+		   CIFS_CPHTXT_SIZE);
 
 	/* make secondary_key/nonce as session key */
 	memcpy(ses->auth_key.response, sec_key, CIFS_SESS_KEY_SIZE);

fs/smb/common/Makefile

@@ -3,5 +3,4 @@
 # Makefile for Linux filesystem routines that are shared by client and server.
 #
 
-obj-$(CONFIG_SMBFS) += cifs_arc4.o
 obj-$(CONFIG_SMBFS) += cifs_md4.o

fs/smb/common/arc4.h

@@ -10,6 +10,7 @@ config SMB_SERVER
 	select CRYPTO_MD5
 	select CRYPTO_HMAC
 	select CRYPTO_ECB
+	select CRYPTO_LIB_ARC4
 	select CRYPTO_LIB_DES
 	select CRYPTO_LIB_SHA256
 	select CRYPTO_SHA256

fs/smb/common/cifs_arc4.c

@@ -20,6 +20,7 @@
 #include "glob.h"
 
 #include <linux/fips.h>
+#include <crypto/arc4.h>
 #include <crypto/des.h>
 
 #include "server.h"
@@ -29,7 +30,6 @@
 #include "mgmt/user_config.h"
 #include "crypto_ctx.h"
 #include "transport_ipc.h"
-#include "../common/arc4.h"
 
 /*
  * Fixed format data defining GSS header and fixed string
@@ -365,10 +365,9 @@ int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
 		if (!ctx_arc4)
 			return -ENOMEM;
 
-		cifs_arc4_setkey(ctx_arc4, sess->sess_key,
-				 SMB2_NTLMV2_SESSKEY_SIZE);
-		cifs_arc4_crypt(ctx_arc4, sess->sess_key,
-				(char *)authblob + sess_key_off, sess_key_len);
+		arc4_setkey(ctx_arc4, sess->sess_key, SMB2_NTLMV2_SESSKEY_SIZE);
+		arc4_crypt(ctx_arc4, sess->sess_key,
+			   (char *)authblob + sess_key_off, sess_key_len);
 		kfree_sensitive(ctx_arc4);
 	}