crypto: cfb - add support for Cipher FeedBack mode (a7d85e06) · Commits · 戴 / test

crypto/Kconfig

+8 −0

Original line number	Diff line number	Diff line
		@@ -320,6 +320,14 @@ config CRYPTO_CBC
		CBC: Cipher Block Chaining mode
		This block cipher algorithm is required for IPSec.

		config CRYPTO_CFB
		tristate "CFB support"
		select CRYPTO_BLKCIPHER
		select CRYPTO_MANAGER
		help
		CFB: Cipher FeedBack mode
		This block cipher algorithm is required for TPM2 Cryptography.

		config CRYPTO_CTR
		tristate "CTR support"
		select CRYPTO_BLKCIPHER

crypto/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -78,6 +78,7 @@ obj-$(CONFIG_CRYPTO_TGR192) += tgr192.o
		obj-$(CONFIG_CRYPTO_GF128MUL) += gf128mul.o
		obj-$(CONFIG_CRYPTO_ECB) += ecb.o
		obj-$(CONFIG_CRYPTO_CBC) += cbc.o
		obj-$(CONFIG_CRYPTO_CFB) += cfb.o
		obj-$(CONFIG_CRYPTO_PCBC) += pcbc.o
		obj-$(CONFIG_CRYPTO_CTS) += cts.o
		obj-$(CONFIG_CRYPTO_LRW) += lrw.o

crypto/cfb.c

0 → 100644

+353 −0

Original line number	Diff line number	Diff line
		//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/skcipher.h>
		#include <linux/err.h>
		#include <linux/init.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/slab.h>
		#include <linux/string.h>
		#include <linux/types.h>

		struct crypto_cfb_ctx {
		struct crypto_cipher *child;
		};

		static unsigned int crypto_cfb_bsize(struct crypto_skcipher *tfm)
		{
		struct crypto_cfb_ctx *ctx = crypto_skcipher_ctx(tfm);
		struct crypto_cipher *child = ctx->child;

		return crypto_cipher_blocksize(child);
		}

		static void crypto_cfb_encrypt_one(struct crypto_skcipher *tfm,
		const u8 src, u8 dst)
		{
		struct crypto_cfb_ctx *ctx = crypto_skcipher_ctx(tfm);

		crypto_cipher_encrypt_one(ctx->child, dst, src);
		}

		/* final encrypt and decrypt is the same */
		static void crypto_cfb_final(struct skcipher_walk *walk,
		struct crypto_skcipher *tfm)
		{
		const unsigned int bsize = crypto_cfb_bsize(tfm);
		const unsigned long alignmask = crypto_skcipher_alignmask(tfm);
		u8 tmp[bsize + 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);
		memcpy(iv, dst, bsize);

		src += bsize;
		dst += bsize;
		} while ((nbytes -= bsize) >= 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[bsize];

		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, iv, 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 *iv = walk->iv;
		u8 tmp[bsize];

		do {
		crypto_cfb_encrypt_one(tfm, iv, tmp);
		memcpy(iv, src, bsize);
		crypto_xor(src, tmp, bsize);
		src += bsize;
		} while ((nbytes -= bsize) >= bsize);

		memcpy(walk->iv, iv, 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_setkey(struct crypto_skcipher parent, const u8 key,
		unsigned int keylen)
		{
		struct crypto_cfb_ctx *ctx = crypto_skcipher_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_skcipher_get_flags(parent) &
		CRYPTO_TFM_REQ_MASK);
		err = crypto_cipher_setkey(child, key, keylen);
		crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
		CRYPTO_TFM_RES_MASK);
		return err;
		}

		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_init_tfm(struct crypto_skcipher *tfm)
		{
		struct skcipher_instance *inst = skcipher_alg_instance(tfm);
		struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
		struct crypto_cfb_ctx *ctx = crypto_skcipher_ctx(tfm);
		struct crypto_cipher *cipher;

		cipher = crypto_spawn_cipher(spawn);
		if (IS_ERR(cipher))
		return PTR_ERR(cipher);

		ctx->child = cipher;
		return 0;
		}

		static void crypto_cfb_exit_tfm(struct crypto_skcipher *tfm)
		{
		struct crypto_cfb_ctx *ctx = crypto_skcipher_ctx(tfm);

		crypto_free_cipher(ctx->child);
		}

		static void crypto_cfb_free(struct skcipher_instance *inst)
		{
		crypto_drop_skcipher(skcipher_instance_ctx(inst));
		kfree(inst);
		}

		static int crypto_cfb_create(struct crypto_template tmpl, struct rtattr *tb)
		{
		struct skcipher_instance *inst;
		struct crypto_attr_type *algt;
		struct crypto_spawn *spawn;
		struct crypto_alg *alg;
		u32 mask;
		int err;

		err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
		if (err)
		return err;

		inst = kzalloc(sizeof(inst) + sizeof(spawn), GFP_KERNEL);
		if (!inst)
		return -ENOMEM;

		algt = crypto_get_attr_type(tb);
		err = PTR_ERR(algt);
		if (IS_ERR(algt))
		goto err_free_inst;

		mask = CRYPTO_ALG_TYPE_MASK \|
		crypto_requires_off(algt->type, algt->mask,
		CRYPTO_ALG_NEED_FALLBACK);

		alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, mask);
		err = PTR_ERR(alg);
		if (IS_ERR(alg))
		goto err_free_inst;

		spawn = skcipher_instance_ctx(inst);
		err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
		CRYPTO_ALG_TYPE_MASK);
		crypto_mod_put(alg);
		if (err)
		goto err_free_inst;

		err = crypto_inst_setname(skcipher_crypto_instance(inst), "cfb", alg);
		if (err)
		goto err_drop_spawn;

		inst->alg.base.cra_priority = alg->cra_priority;
		/* we're a stream cipher independend of the crypto cra_blocksize */
		inst->alg.base.cra_blocksize = 1;
		inst->alg.base.cra_alignmask = alg->cra_alignmask;

		inst->alg.ivsize = alg->cra_blocksize;
		inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
		inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;

		inst->alg.base.cra_ctxsize = sizeof(struct crypto_cfb_ctx);

		inst->alg.init = crypto_cfb_init_tfm;
		inst->alg.exit = crypto_cfb_exit_tfm;

		inst->alg.setkey = crypto_cfb_setkey;
		inst->alg.encrypt = crypto_cfb_encrypt;
		inst->alg.decrypt = crypto_cfb_decrypt;

		inst->free = crypto_cfb_free;

		err = skcipher_register_instance(tmpl, inst);
		if (err)
		goto err_drop_spawn;

		out:
		return err;

		err_drop_spawn:
		crypto_drop_spawn(spawn);
		err_free_inst:
		kfree(inst);
		goto out;
		}

		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);
		}

		module_init(crypto_cfb_module_init);
		module_exit(crypto_cfb_module_exit);

		MODULE_LICENSE("GPL");
		MODULE_DESCRIPTION("CFB block cipher algorithm");
		MODULE_ALIAS_CRYPTO("cfb");

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