[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, 344 insertions, 0 deletions

diff --git a/crypto/cbc.c b/crypto/cbc.c
new file mode 100644
index 000000000000..f5542b4db387
--- /dev/null
+++ b/crypto/cbc.c
@@ -0,0 +1,344 @@
+/*
+ * CBC: Cipher Block Chaining 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_cbc_ctx {
+        struct crypto_cipher *child;
+        void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
+};
+
+static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key,
+                             unsigned int keylen)
+{
+        struct crypto_cbc_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_cbc_encrypt_segment(struct blkcipher_desc *desc,
+                                      struct blkcipher_walk *walk,
+                                      struct crypto_cipher *tfm,
+                                      void (*xor)(u8 *, const u8 *,
+                                                  unsigned int))
+{
+        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
+                crypto_cipher_alg(tfm)->cia_encrypt;
+        int bsize = crypto_cipher_blocksize(tfm);
+        unsigned int nbytes = walk->nbytes;
+        u8 *src = walk->src.virt.addr;
+        u8 *dst = walk->dst.virt.addr;
+        u8 *iv = walk->iv;
+
+        do {
+                xor(iv, src, bsize);
+                fn(crypto_cipher_tfm(tfm), dst, iv);
+                memcpy(iv, dst, bsize);
+
+                src += bsize;
+                dst += bsize;
+        } while ((nbytes -= bsize) >= bsize);
+
+        return nbytes;
+}
+
+static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc,
+                                      struct blkcipher_walk *walk,
+                                      struct crypto_cipher *tfm,
+                                      void (*xor)(u8 *, const u8 *,
+                                                  unsigned int))
+{
+        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
+                crypto_cipher_alg(tfm)->cia_encrypt;
+        int bsize = crypto_cipher_blocksize(tfm);
+        unsigned int nbytes = walk->nbytes;
+        u8 *src = walk->src.virt.addr;
+        u8 *iv = walk->iv;
+
+        do {
+                xor(src, iv, bsize);
+                fn(crypto_cipher_tfm(tfm), src, src);
+                iv = src;
+
+                src += bsize;
+        } while ((nbytes -= bsize) >= bsize);
+
+        memcpy(walk->iv, iv, bsize);
+
+        return nbytes;
+}
+
+static int crypto_cbc_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_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
+        struct crypto_cipher *child = ctx->child;
+        void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
+        int err;
+
+        blkcipher_walk_init(&walk, dst, src, nbytes);
+        err = blkcipher_walk_virt(desc, &walk);
+
+        while ((nbytes = walk.nbytes)) {
+                if (walk.src.virt.addr == walk.dst.virt.addr)
+                        nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child,
+                                                            xor);
+                else
+                        nbytes = crypto_cbc_encrypt_segment(desc, &walk, child,
+                                                            xor);
+                err = blkcipher_walk_done(desc, &walk, nbytes);
+        }
+
+        return err;
+}
+
+static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc,
+                                      struct blkcipher_walk *walk,
+                                      struct crypto_cipher *tfm,
+                                      void (*xor)(u8 *, const u8 *,
+                                                  unsigned int))
+{
+        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
+                crypto_cipher_alg(tfm)->cia_decrypt;
+        int bsize = crypto_cipher_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(crypto_cipher_tfm(tfm), dst, src);
+                xor(dst, iv, bsize);
+                iv = src;
+
+                src += bsize;
+                dst += bsize;
+        } while ((nbytes -= bsize) >= bsize);
+
+        memcpy(walk->iv, iv, bsize);
+
+        return nbytes;
+}
+
+static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc,
+                                      struct blkcipher_walk *walk,
+                                      struct crypto_cipher *tfm,
+                                      void (*xor)(u8 *, const u8 *,
+                                                  unsigned int))
+{
+        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
+                crypto_cipher_alg(tfm)->cia_decrypt;
+        int bsize = crypto_cipher_blocksize(tfm);
+        unsigned long alignmask = crypto_cipher_alignmask(tfm);
+        unsigned int nbytes = walk->nbytes;
+        u8 *src = walk->src.virt.addr;
+        u8 stack[bsize + alignmask];
+        u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
+
+        memcpy(first_iv, walk->iv, bsize);
+
+        /* Start of the last block. */
+        src += nbytes - nbytes % bsize - bsize;
+        memcpy(walk->iv, src, bsize);
+
+        for (;;) {
+                fn(crypto_cipher_tfm(tfm), src, src);
+                if ((nbytes -= bsize) < bsize)
+                        break;
+                xor(src, src - bsize, bsize);
+                src -= bsize;
+        }
+
+        xor(src, first_iv, bsize);
+
+        return nbytes;
+}
+
+static int crypto_cbc_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_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
+        struct crypto_cipher *child = ctx->child;
+        void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
+        int err;
+
+        blkcipher_walk_init(&walk, dst, src, nbytes);
+        err = blkcipher_walk_virt(desc, &walk);
+
+        while ((nbytes = walk.nbytes)) {
+                if (walk.src.virt.addr == walk.dst.virt.addr)
+                        nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child,
+                                                            xor);
+                else
+                        nbytes = crypto_cbc_decrypt_segment(desc, &walk, child,
+                                                            xor);
+                err = blkcipher_walk_done(desc, &walk, nbytes);
+        }
+
+        return err;
+}
+
+static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
+{
+        do {
+                *a++ ^= *b++;
+        } while (--bs);
+}
+
+static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
+{
+        u32 *a = (u32 *)dst;
+        u32 *b = (u32 *)src;
+
+        do {
+                *a++ ^= *b++;
+        } while ((bs -= 4));
+}
+
+static void xor_64(u8 *a, const u8 *b, unsigned int bs)
+{
+        ((u32 *)a)[0] ^= ((u32 *)b)[0];
+        ((u32 *)a)[1] ^= ((u32 *)b)[1];
+}
+
+static void xor_128(u8 *a, const u8 *b, unsigned int bs)
+{
+        ((u32 *)a)[0] ^= ((u32 *)b)[0];
+        ((u32 *)a)[1] ^= ((u32 *)b)[1];
+        ((u32 *)a)[2] ^= ((u32 *)b)[2];
+        ((u32 *)a)[3] ^= ((u32 *)b)[3];
+}
+
+static int crypto_cbc_init_tfm(struct crypto_tfm *tfm)
+{
+        struct crypto_instance *inst = (void *)tfm->__crt_alg;
+        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
+        struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
+
+        switch (crypto_tfm_alg_blocksize(tfm)) {
+        case 8:
+                ctx->xor = xor_64;
+                break;
+
+        case 16:
+                ctx->xor = xor_128;
+                break;
+
+        default:
+                if (crypto_tfm_alg_blocksize(tfm) % 4)
+                        ctx->xor = xor_byte;
+                else
+                        ctx->xor = xor_quad;
+        }
+
+        tfm = crypto_spawn_tfm(spawn);
+        if (IS_ERR(tfm))
+                return PTR_ERR(tfm);
+
+        ctx->child = crypto_cipher_cast(tfm);
+        return 0;
+}
+
+static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm)
+{
+        struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
+        crypto_free_cipher(ctx->child);
+}
+
+static struct crypto_instance *crypto_cbc_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("cbc", 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;
+
+        if (!(alg->cra_blocksize % 4))
+                inst->alg.cra_alignmask |= 3;
+        inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
+        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_cbc_ctx);
+
+        inst->alg.cra_init = crypto_cbc_init_tfm;
+        inst->alg.cra_exit = crypto_cbc_exit_tfm;
+
+        inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey;
+        inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt;
+        inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt;
+
+out_put_alg:
+        crypto_mod_put(alg);
+        return inst;
+}
+
+static void crypto_cbc_free(struct crypto_instance *inst)
+{
+        crypto_drop_spawn(crypto_instance_ctx(inst));
+        kfree(inst);
+}
+
+static struct crypto_template crypto_cbc_tmpl = {
+        .name = "cbc",
+        .alloc = crypto_cbc_alloc,
+        .free = crypto_cbc_free,
+        .module = THIS_MODULE,
+};
+
+static int __init crypto_cbc_module_init(void)
+{
+        return crypto_register_template(&crypto_cbc_tmpl);
+}
+
+static void __exit crypto_cbc_module_exit(void)
+{
+        crypto_unregister_template(&crypto_cbc_tmpl);
+}
+
+module_init(crypto_cbc_module_init);
+module_exit(crypto_cbc_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CBC block cipher algorithm");