crypto: cbc - Export CBC implementation
This patch moves the core CBC implementation into a header file
so that it can be reused by drivers implementing CBC.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/cbc.h b/include/crypto/cbc.h
new file mode 100644
index 0000000..f5b8bfc
--- /dev/null
+++ b/include/crypto/cbc.h
@@ -0,0 +1,146 @@
+/*
+ * CBC: Cipher Block Chaining mode
+ *
+ * Copyright (c) 2016 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#ifndef _CRYPTO_CBC_H
+#define _CRYPTO_CBC_H
+
+#include <crypto/internal/skcipher.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+static inline int crypto_cbc_encrypt_segment(
+ struct skcipher_walk *walk, struct crypto_skcipher *tfm,
+ void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
+{
+ unsigned int bsize = crypto_skcipher_blocksize(tfm);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 *dst = walk->dst.virt.addr;
+ u8 *iv = walk->iv;
+
+ do {
+ crypto_xor(iv, src, bsize);
+ fn(tfm, iv, dst);
+ memcpy(iv, dst, bsize);
+
+ src += bsize;
+ dst += bsize;
+ } while ((nbytes -= bsize) >= bsize);
+
+ return nbytes;
+}
+
+static inline int crypto_cbc_encrypt_inplace(
+ struct skcipher_walk *walk, struct crypto_skcipher *tfm,
+ void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
+{
+ unsigned int bsize = crypto_skcipher_blocksize(tfm);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 *iv = walk->iv;
+
+ do {
+ crypto_xor(src, iv, bsize);
+ fn(tfm, src, src);
+ iv = src;
+
+ src += bsize;
+ } while ((nbytes -= bsize) >= bsize);
+
+ memcpy(walk->iv, iv, bsize);
+
+ return nbytes;
+}
+
+static inline int crypto_cbc_encrypt_walk(struct skcipher_request *req,
+ void (*fn)(struct crypto_skcipher *,
+ const u8 *, u8 *))
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct skcipher_walk walk;
+ int err;
+
+ err = skcipher_walk_virt(&walk, req, false);
+
+ while (walk.nbytes) {
+ if (walk.src.virt.addr == walk.dst.virt.addr)
+ err = crypto_cbc_encrypt_inplace(&walk, tfm, fn);
+ else
+ err = crypto_cbc_encrypt_segment(&walk, tfm, fn);
+ err = skcipher_walk_done(&walk, err);
+ }
+
+ return err;
+}
+
+static inline int crypto_cbc_decrypt_segment(
+ struct skcipher_walk *walk, struct crypto_skcipher *tfm,
+ void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
+{
+ unsigned int bsize = crypto_skcipher_blocksize(tfm);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 *dst = walk->dst.virt.addr;
+ u8 *iv = walk->iv;
+
+ do {
+ fn(tfm, src, dst);
+ crypto_xor(dst, iv, bsize);
+ iv = src;
+
+ src += bsize;
+ dst += bsize;
+ } while ((nbytes -= bsize) >= bsize);
+
+ memcpy(walk->iv, iv, bsize);
+
+ return nbytes;
+}
+
+static inline int crypto_cbc_decrypt_inplace(
+ struct skcipher_walk *walk, struct crypto_skcipher *tfm,
+ void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
+{
+ unsigned int bsize = crypto_skcipher_blocksize(tfm);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 last_iv[bsize];
+
+ /* Start of the last block. */
+ src += nbytes - (nbytes & (bsize - 1)) - bsize;
+ memcpy(last_iv, src, bsize);
+
+ for (;;) {
+ fn(tfm, src, src);
+ if ((nbytes -= bsize) < bsize)
+ break;
+ crypto_xor(src, src - bsize, bsize);
+ src -= bsize;
+ }
+
+ crypto_xor(src, walk->iv, bsize);
+ memcpy(walk->iv, last_iv, bsize);
+
+ return nbytes;
+}
+
+static inline int crypto_cbc_decrypt_blocks(
+ struct skcipher_walk *walk, struct crypto_skcipher *tfm,
+ void (*fn)(struct crypto_skcipher *, const u8 *, u8 *))
+{
+ if (walk->src.virt.addr == walk->dst.virt.addr)
+ return crypto_cbc_decrypt_inplace(walk, tfm, fn);
+ else
+ return crypto_cbc_decrypt_segment(walk, tfm, fn);
+}
+
+#endif /* _CRYPTO_CBC_H */