[CRYPTO] cipher: Added block ciphers for CBC/ECB

This patch adds two block cipher algorithms, CBC and ECB.  These
are implemented as templates on top of existing single-block cipher
algorithms.  They invoke the single-block cipher through the new
encrypt_one/decrypt_one interface.

This also optimises the in-place encryption and decryption to remove
the cost of an IV copy each round.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 181 insertions, 0 deletions

diff --git a/crypto/ecb.c b/crypto/ecb.c
new file mode 100644
index 000000000000..f239aa9c4017
--- /dev/null
+++ b/crypto/ecb.c
@@ -0,0 +1,181 @@
+/*
+ * ECB: Electronic CodeBook mode
+ *
+ * Copyright (c) 2006 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.
+ *
+ */
+
+#include <crypto/algapi.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+
+struct crypto_ecb_ctx {
+        struct crypto_cipher *child;
+};
+
+static int crypto_ecb_setkey(struct crypto_tfm *parent, const u8 *key,
+                             unsigned int keylen)
+{
+        struct crypto_ecb_ctx *ctx = crypto_tfm_ctx(parent);
+        struct crypto_cipher *child = ctx->child;
+        int err;
+
+        crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+        crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
+                                       CRYPTO_TFM_REQ_MASK);
+        err = crypto_cipher_setkey(child, key, keylen);
+        crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
+                                     CRYPTO_TFM_RES_MASK);
+        return err;
+}
+
+static int crypto_ecb_crypt(struct blkcipher_desc *desc,
+                            struct blkcipher_walk *walk,
+                            struct crypto_cipher *tfm,
+                            void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
+{
+        int bsize = crypto_cipher_blocksize(tfm);
+        unsigned int nbytes;
+        int err;
+
+        err = blkcipher_walk_virt(desc, walk);
+
+        while ((nbytes = walk->nbytes)) {
+                u8 *wsrc = walk->src.virt.addr;
+                u8 *wdst = walk->dst.virt.addr;
+
+                do {
+                        fn(crypto_cipher_tfm(tfm), wdst, wsrc);
+        
+                        wsrc += bsize;
+                        wdst += bsize;
+                } while ((nbytes -= bsize) >= bsize);
+
+                err = blkcipher_walk_done(desc, walk, nbytes);
+        }
+
+        return err;
+}
+
+static int crypto_ecb_encrypt(struct blkcipher_desc *desc,
+                              struct scatterlist *dst, struct scatterlist *src,
+                              unsigned int nbytes)
+{
+        struct blkcipher_walk walk;
+        struct crypto_blkcipher *tfm = desc->tfm;
+        struct crypto_ecb_ctx *ctx = crypto_blkcipher_ctx(tfm);
+        struct crypto_cipher *child = ctx->child;
+
+        blkcipher_walk_init(&walk, dst, src, nbytes);
+        return crypto_ecb_crypt(desc, &walk, child,
+                                crypto_cipher_alg(child)->cia_encrypt);
+}
+
+static int crypto_ecb_decrypt(struct blkcipher_desc *desc,
+                              struct scatterlist *dst, struct scatterlist *src,
+                              unsigned int nbytes)
+{
+        struct blkcipher_walk walk;
+        struct crypto_blkcipher *tfm = desc->tfm;
+        struct crypto_ecb_ctx *ctx = crypto_blkcipher_ctx(tfm);
+        struct crypto_cipher *child = ctx->child;
+
+        blkcipher_walk_init(&walk, dst, src, nbytes);
+        return crypto_ecb_crypt(desc, &walk, child,
+                                crypto_cipher_alg(child)->cia_decrypt);
+}
+
+static int crypto_ecb_init_tfm(struct crypto_tfm *tfm)
+{
+        struct crypto_instance *inst = (void *)tfm->__crt_alg;
+        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
+        struct crypto_ecb_ctx *ctx = crypto_tfm_ctx(tfm);
+
+        tfm = crypto_spawn_tfm(spawn);
+        if (IS_ERR(tfm))
+                return PTR_ERR(tfm);
+
+        ctx->child = crypto_cipher_cast(tfm);
+        return 0;
+}
+
+static void crypto_ecb_exit_tfm(struct crypto_tfm *tfm)
+{
+        struct crypto_ecb_ctx *ctx = crypto_tfm_ctx(tfm);
+        crypto_free_cipher(ctx->child);
+}
+
+static struct crypto_instance *crypto_ecb_alloc(void *param, unsigned int len)
+{
+        struct crypto_instance *inst;
+        struct crypto_alg *alg;
+
+        alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,
+                                  CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
+        if (IS_ERR(alg))
+                return ERR_PTR(PTR_ERR(alg));
+
+        inst = crypto_alloc_instance("ecb", alg);
+        if (IS_ERR(inst))
+                goto out_put_alg;
+
+        inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
+        inst->alg.cra_priority = alg->cra_priority;
+        inst->alg.cra_blocksize = alg->cra_blocksize;
+        inst->alg.cra_alignmask = alg->cra_alignmask;
+        inst->alg.cra_type = &crypto_blkcipher_type;
+
+        inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
+        inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
+
+        inst->alg.cra_ctxsize = sizeof(struct crypto_ecb_ctx);
+
+        inst->alg.cra_init = crypto_ecb_init_tfm;
+        inst->alg.cra_exit = crypto_ecb_exit_tfm;
+
+        inst->alg.cra_blkcipher.setkey = crypto_ecb_setkey;
+        inst->alg.cra_blkcipher.encrypt = crypto_ecb_encrypt;
+        inst->alg.cra_blkcipher.decrypt = crypto_ecb_decrypt;
+
+out_put_alg:
+        crypto_mod_put(alg);
+        return inst;
+}
+
+static void crypto_ecb_free(struct crypto_instance *inst)
+{
+        crypto_drop_spawn(crypto_instance_ctx(inst));
+        kfree(inst);
+}
+
+static struct crypto_template crypto_ecb_tmpl = {
+        .name = "ecb",
+        .alloc = crypto_ecb_alloc,
+        .free = crypto_ecb_free,
+        .module = THIS_MODULE,
+};
+
+static int __init crypto_ecb_module_init(void)
+{
+        return crypto_register_template(&crypto_ecb_tmpl);
+}
+
+static void __exit crypto_ecb_module_exit(void)
+{
+        crypto_unregister_template(&crypto_ecb_tmpl);
+}
+
+module_init(crypto_ecb_module_init);
+module_exit(crypto_ecb_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ECB block cipher algorithm");