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-rw-r--r--crypto/cfb.c254
1 files changed, 0 insertions, 254 deletions
diff --git a/crypto/cfb.c b/crypto/cfb.c
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index 5c36b7b65e..0000000000
--- a/crypto/cfb.c
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-// SPDX-License-Identifier: GPL-2.0
-/*
- * CFB: Cipher FeedBack mode
- *
- * Copyright (c) 2018 James.Bottomley@HansenPartnership.com
- *
- * CFB is a stream cipher mode which is layered on to a block
- * encryption scheme. It works very much like a one time pad where
- * the pad is generated initially from the encrypted IV and then
- * subsequently from the encrypted previous block of ciphertext. The
- * pad is XOR'd into the plain text to get the final ciphertext.
- *
- * The scheme of CFB is best described by wikipedia:
- *
- * https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#CFB
- *
- * Note that since the pad for both encryption and decryption is
- * generated by an encryption operation, CFB never uses the block
- * decryption function.
- */
-
-#include <crypto/algapi.h>
-#include <crypto/internal/cipher.h>
-#include <crypto/internal/skcipher.h>
-#include <linux/err.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/string.h>
-
-static unsigned int crypto_cfb_bsize(struct crypto_skcipher *tfm)
-{
- return crypto_cipher_blocksize(skcipher_cipher_simple(tfm));
-}
-
-static void crypto_cfb_encrypt_one(struct crypto_skcipher *tfm,
- const u8 *src, u8 *dst)
-{
- crypto_cipher_encrypt_one(skcipher_cipher_simple(tfm), dst, src);
-}
-
-/* final encrypt and decrypt is the same */
-static void crypto_cfb_final(struct skcipher_walk *walk,
- struct crypto_skcipher *tfm)
-{
- const unsigned long alignmask = crypto_skcipher_alignmask(tfm);
- u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
- u8 *stream = PTR_ALIGN(tmp + 0, alignmask + 1);
- u8 *src = walk->src.virt.addr;
- u8 *dst = walk->dst.virt.addr;
- u8 *iv = walk->iv;
- unsigned int nbytes = walk->nbytes;
-
- crypto_cfb_encrypt_one(tfm, iv, stream);
- crypto_xor_cpy(dst, stream, src, nbytes);
-}
-
-static int crypto_cfb_encrypt_segment(struct skcipher_walk *walk,
- struct crypto_skcipher *tfm)
-{
- const unsigned int bsize = crypto_cfb_bsize(tfm);
- unsigned int nbytes = walk->nbytes;
- u8 *src = walk->src.virt.addr;
- u8 *dst = walk->dst.virt.addr;
- u8 *iv = walk->iv;
-
- do {
- crypto_cfb_encrypt_one(tfm, iv, dst);
- crypto_xor(dst, src, bsize);
- iv = dst;
-
- src += bsize;
- dst += bsize;
- } while ((nbytes -= bsize) >= bsize);
-
- memcpy(walk->iv, iv, bsize);
-
- return nbytes;
-}
-
-static int crypto_cfb_encrypt_inplace(struct skcipher_walk *walk,
- struct crypto_skcipher *tfm)
-{
- const unsigned int bsize = crypto_cfb_bsize(tfm);
- unsigned int nbytes = walk->nbytes;
- u8 *src = walk->src.virt.addr;
- u8 *iv = walk->iv;
- u8 tmp[MAX_CIPHER_BLOCKSIZE];
-
- do {
- crypto_cfb_encrypt_one(tfm, iv, tmp);
- crypto_xor(src, tmp, bsize);
- iv = src;
-
- src += bsize;
- } while ((nbytes -= bsize) >= bsize);
-
- memcpy(walk->iv, iv, bsize);
-
- return nbytes;
-}
-
-static int crypto_cfb_encrypt(struct skcipher_request *req)
-{
- struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
- struct skcipher_walk walk;
- unsigned int bsize = crypto_cfb_bsize(tfm);
- int err;
-
- err = skcipher_walk_virt(&walk, req, false);
-
- while (walk.nbytes >= bsize) {
- if (walk.src.virt.addr == walk.dst.virt.addr)
- err = crypto_cfb_encrypt_inplace(&walk, tfm);
- else
- err = crypto_cfb_encrypt_segment(&walk, tfm);
- err = skcipher_walk_done(&walk, err);
- }
-
- if (walk.nbytes) {
- crypto_cfb_final(&walk, tfm);
- err = skcipher_walk_done(&walk, 0);
- }
-
- return err;
-}
-
-static int crypto_cfb_decrypt_segment(struct skcipher_walk *walk,
- struct crypto_skcipher *tfm)
-{
- const unsigned int bsize = crypto_cfb_bsize(tfm);
- unsigned int nbytes = walk->nbytes;
- u8 *src = walk->src.virt.addr;
- u8 *dst = walk->dst.virt.addr;
- u8 *iv = walk->iv;
-
- do {
- crypto_cfb_encrypt_one(tfm, iv, dst);
- crypto_xor(dst, src, bsize);
- iv = src;
-
- src += bsize;
- dst += bsize;
- } while ((nbytes -= bsize) >= bsize);
-
- memcpy(walk->iv, iv, bsize);
-
- return nbytes;
-}
-
-static int crypto_cfb_decrypt_inplace(struct skcipher_walk *walk,
- struct crypto_skcipher *tfm)
-{
- const unsigned int bsize = crypto_cfb_bsize(tfm);
- unsigned int nbytes = walk->nbytes;
- u8 *src = walk->src.virt.addr;
- u8 * const iv = walk->iv;
- u8 tmp[MAX_CIPHER_BLOCKSIZE];
-
- do {
- crypto_cfb_encrypt_one(tfm, iv, tmp);
- memcpy(iv, src, bsize);
- crypto_xor(src, tmp, bsize);
- src += bsize;
- } while ((nbytes -= bsize) >= bsize);
-
- return nbytes;
-}
-
-static int crypto_cfb_decrypt_blocks(struct skcipher_walk *walk,
- struct crypto_skcipher *tfm)
-{
- if (walk->src.virt.addr == walk->dst.virt.addr)
- return crypto_cfb_decrypt_inplace(walk, tfm);
- else
- return crypto_cfb_decrypt_segment(walk, tfm);
-}
-
-static int crypto_cfb_decrypt(struct skcipher_request *req)
-{
- struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
- struct skcipher_walk walk;
- const unsigned int bsize = crypto_cfb_bsize(tfm);
- int err;
-
- err = skcipher_walk_virt(&walk, req, false);
-
- while (walk.nbytes >= bsize) {
- err = crypto_cfb_decrypt_blocks(&walk, tfm);
- err = skcipher_walk_done(&walk, err);
- }
-
- if (walk.nbytes) {
- crypto_cfb_final(&walk, tfm);
- err = skcipher_walk_done(&walk, 0);
- }
-
- return err;
-}
-
-static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
-{
- struct skcipher_instance *inst;
- struct crypto_alg *alg;
- int err;
-
- inst = skcipher_alloc_instance_simple(tmpl, tb);
- if (IS_ERR(inst))
- return PTR_ERR(inst);
-
- alg = skcipher_ialg_simple(inst);
-
- /* CFB mode is a stream cipher. */
- inst->alg.base.cra_blocksize = 1;
-
- /*
- * To simplify the implementation, configure the skcipher walk to only
- * give a partial block at the very end, never earlier.
- */
- inst->alg.chunksize = alg->cra_blocksize;
-
- inst->alg.encrypt = crypto_cfb_encrypt;
- inst->alg.decrypt = crypto_cfb_decrypt;
-
- err = skcipher_register_instance(tmpl, inst);
- if (err)
- inst->free(inst);
-
- return err;
-}
-
-static struct crypto_template crypto_cfb_tmpl = {
- .name = "cfb",
- .create = crypto_cfb_create,
- .module = THIS_MODULE,
-};
-
-static int __init crypto_cfb_module_init(void)
-{
- return crypto_register_template(&crypto_cfb_tmpl);
-}
-
-static void __exit crypto_cfb_module_exit(void)
-{
- crypto_unregister_template(&crypto_cfb_tmpl);
-}
-
-subsys_initcall(crypto_cfb_module_init);
-module_exit(crypto_cfb_module_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("CFB block cipher mode of operation");
-MODULE_ALIAS_CRYPTO("cfb");
-MODULE_IMPORT_NS(CRYPTO_INTERNAL);
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