cifs: fork arc4 and create a separate module for it for cifs and other users

We can not drop ARC4 and basically destroy CIFS connectivity for
almost all CIFS users so create a new forked ARC4 module that CIFS and other
subsystems that have a hard dependency on ARC4 can use.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/fs/cifs_common/arc4.h b/fs/cifs_common/arc4.h
new file mode 100644
index 000000000000..12e71ec033a1
--- /dev/null
+++ b/fs/cifs_common/arc4.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Common values for ARC4 Cipher Algorithm
+ */
+
+#ifndef _CRYPTO_ARC4_H
+#define _CRYPTO_ARC4_H
+
+#include <linux/types.h>
+
+#define ARC4_MIN_KEY_SIZE	1
+#define ARC4_MAX_KEY_SIZE	256
+#define ARC4_BLOCK_SIZE		1
+
+struct arc4_ctx {
+	u32 S[256];
+	u32 x, y;
+};
+
+int cifs_arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len);
+void cifs_arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len);
+
+#endif /* _CRYPTO_ARC4_H */