[CRYPTO] ctr: Refactor into ctr and rfc3686

As discussed previously, this patch moves the basic CTR functionality
into a chainable algorithm called ctr. The IPsec-specific variant of
it is now placed on top with the name rfc3686.

So ctr(aes) gives a chainable cipher with IV size 16 while the IPsec
variant will be called rfc3686(ctr(aes)). This patch also adjusts
gcm accordingly.

Signed-off-by: Herbert Xu <[e-mail]>

crypto/ctr.c

···
  */
 
 #include <crypto/algapi.h>
+#include <crypto/ctr.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
···
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 
-struct ctr_instance_ctx {
-	struct crypto_spawn alg;
-	unsigned int noncesize;
-	unsigned int ivsize;
-	unsigned int countersize;
-};
-
 struct crypto_ctr_ctx {
 	struct crypto_cipher *child;
-	u8 *nonce;
+};
+
+struct crypto_rfc3686_ctx {
+	struct crypto_blkcipher *child;
+	u8 nonce[CTR_RFC3686_NONCE_SIZE];
 };
 
 static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
···
 {
 	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
 	struct crypto_cipher *child = ctx->child;
-	struct ctr_instance_ctx *ictx =
-		crypto_instance_ctx(crypto_tfm_alg_instance(parent));
-	unsigned int noncelen = ictx->noncesize;
-	int err = 0;
-
-	/* the nonce is stored in bytes at end of key */
-	if (keylen < noncelen)
-		return  -EINVAL;
-
-	memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);
-
-	keylen -=  noncelen;
+	int err;
 
 	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
···
 }
 
 static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
-				   struct crypto_cipher *tfm, u8 *ctrblk,
-				   unsigned int countersize)
+				   struct crypto_cipher *tfm)
 {
 	unsigned int bsize = crypto_cipher_blocksize(tfm);
-	u8 *keystream = ctrblk + bsize;
+	unsigned long alignmask = crypto_cipher_alignmask(tfm);
+	u8 *ctrblk = walk->iv;
+	u8 tmp[bsize + alignmask];
+	u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
 	u8 *src = walk->src.virt.addr;
 	u8 *dst = walk->dst.virt.addr;
 	unsigned int nbytes = walk->nbytes;
···
 	crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
 	crypto_xor(keystream, src, nbytes);
 	memcpy(dst, keystream, nbytes);
+
+	crypto_inc(ctrblk, bsize);
 }
 
 static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
-				    struct crypto_cipher *tfm, u8 *ctrblk,
-				    unsigned int countersize)
+				    struct crypto_cipher *tfm)
 {
 	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 		   crypto_cipher_alg(tfm)->cia_encrypt;
 	unsigned int bsize = crypto_cipher_blocksize(tfm);
+	u8 *ctrblk = walk->iv;
 	u8 *src = walk->src.virt.addr;
 	u8 *dst = walk->dst.virt.addr;
 	unsigned int nbytes = walk->nbytes;
···
 		crypto_xor(dst, src, bsize);
 
 		/* increment counter in counterblock */
-		crypto_inc(ctrblk + bsize - countersize, countersize);
+		crypto_inc(ctrblk, bsize);
 
 		src += bsize;
 		dst += bsize;
···
 }
 
 static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
-				    struct crypto_cipher *tfm, u8 *ctrblk,
-				    unsigned int countersize)
+				    struct crypto_cipher *tfm)
 {
 	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 		   crypto_cipher_alg(tfm)->cia_encrypt;
 	unsigned int bsize = crypto_cipher_blocksize(tfm);
+	unsigned long alignmask = crypto_cipher_alignmask(tfm);
 	unsigned int nbytes = walk->nbytes;
+	u8 *ctrblk = walk->iv;
 	u8 *src = walk->src.virt.addr;
-	u8 *keystream = ctrblk + bsize;
+	u8 tmp[bsize + alignmask];
+	u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
 
 	do {
 		/* create keystream */
···
 		crypto_xor(src, keystream, bsize);
 
 		/* increment counter in counterblock */
-		crypto_inc(ctrblk + bsize - countersize, countersize);
+		crypto_inc(ctrblk, bsize);
 
 		src += bsize;
 	} while ((nbytes -= bsize) >= bsize);
···
 	struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
 	struct crypto_cipher *child = ctx->child;
 	unsigned int bsize = crypto_cipher_blocksize(child);
-	struct ctr_instance_ctx *ictx =
-		crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
-	unsigned long alignmask = crypto_cipher_alignmask(child) |
-				  (__alignof__(u32) - 1);
-	u8 cblk[bsize * 2 + alignmask];
-	u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
 	int err;
 
 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt_block(desc, &walk, bsize);
 
-	/* set up counter block */
-	memset(counterblk, 0 , bsize);
-	memcpy(counterblk, ctx->nonce, ictx->noncesize);
-	memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize);
-
-	/* initialize counter portion of counter block */
-	crypto_inc(counterblk + bsize - ictx->countersize, ictx->countersize);
-
 	while (walk.nbytes >= bsize) {
 		if (walk.src.virt.addr == walk.dst.virt.addr)
-			nbytes = crypto_ctr_crypt_inplace(&walk, child,
-							  counterblk,
-							  ictx->countersize);
+			nbytes = crypto_ctr_crypt_inplace(&walk, child);
 		else
-			nbytes = crypto_ctr_crypt_segment(&walk, child,
-							  counterblk,
-							  ictx->countersize);
+			nbytes = crypto_ctr_crypt_segment(&walk, child);
 
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
 
 	if (walk.nbytes) {
-		crypto_ctr_crypt_final(&walk, child, counterblk,
-				       ictx->countersize);
+		crypto_ctr_crypt_final(&walk, child);
 		err = blkcipher_walk_done(desc, &walk, 0);
 	}
 
···
 static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_instance *inst = (void *)tfm->__crt_alg;
-	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
+	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct crypto_cipher *cipher;
 
-	ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
-	if (!ctx->nonce)
-		return -ENOMEM;
-
-	cipher = crypto_spawn_cipher(&ictx->alg);
+	cipher = crypto_spawn_cipher(spawn);
 	if (IS_ERR(cipher))
 		return PTR_ERR(cipher);
 
···
 {
 	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
 
-	kfree(ctx->nonce);
 	crypto_free_cipher(ctx->child);
 }
 
···
 {
 	struct crypto_instance *inst;
 	struct crypto_alg *alg;
-	struct ctr_instance_ctx *ictx;
-	unsigned int noncesize;
-	unsigned int ivsize;
-	unsigned int countersize;
 	int err;
 
 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
···
 	if (IS_ERR(alg))
 		return ERR_PTR(PTR_ERR(alg));
 
-	err = crypto_attr_u32(tb[2], &noncesize);
-	if (err)
-		goto out_put_alg;
-
-	err = crypto_attr_u32(tb[3], &ivsize);
-	if (err)
-		goto out_put_alg;
-
-	err = crypto_attr_u32(tb[4], &countersize);
-	if (err)
-		goto out_put_alg;
-
-	/* verify size of nonce + iv + counter
-	 * counter must be >= 4 bytes.
-	 */
+	/* Block size must be >= 4 bytes. */
 	err = -EINVAL;
-	if (((noncesize + ivsize + countersize) < alg->cra_blocksize) ||
-	    ((noncesize + ivsize) > alg->cra_blocksize) ||
-	    (countersize > alg->cra_blocksize) || (countersize < 4))
+	if (alg->cra_blocksize < 4)
 		goto out_put_alg;
 
 	/* If this is false we'd fail the alignment of crypto_inc. */
-	if ((alg->cra_blocksize - countersize) % 4)
+	if (alg->cra_blocksize % 4)
 		goto out_put_alg;
 
-	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
-	err = -ENOMEM;
-	if (!inst)
-		goto out_put_alg;
+	inst = crypto_alloc_instance("ctr", alg);
+	if (IS_ERR(inst))
+		goto out;
 
-	err = -ENAMETOOLONG;
-	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
-		     "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize,
-		     ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
-		goto err_free_inst;
-	}
-
-	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
-		     "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize,
-		     ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
-		goto err_free_inst;
-	}
-
-	ictx = crypto_instance_ctx(inst);
-	ictx->noncesize = noncesize;
-	ictx->ivsize = ivsize;
-	ictx->countersize = countersize;
-
-	err = crypto_init_spawn(&ictx->alg, alg, inst,
-		CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
-	if (err)
-		goto err_free_inst;
-
-	err = 0;
 	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 	inst->alg.cra_priority = alg->cra_priority;
 	inst->alg.cra_blocksize = 1;
 	inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
 	inst->alg.cra_type = &crypto_blkcipher_type;
 
-	inst->alg.cra_blkcipher.ivsize = ivsize;
-	inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
-					      + noncesize;
-	inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
-					      + noncesize;
+	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_ctr_ctx);
 
···
 	inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
 	inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
 
-err_free_inst:
-	if (err)
-		kfree(inst);
+out:
+	crypto_mod_put(alg);
+	return inst;
 
 out_put_alg:
-	crypto_mod_put(alg);
-
-	if (err)
-		inst = ERR_PTR(err);
-
-	return inst;
+	inst = ERR_PTR(err);
+	goto out;
 }
 
 static void crypto_ctr_free(struct crypto_instance *inst)
 {
-	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
-
-	crypto_drop_spawn(&ictx->alg);
+	crypto_drop_spawn(crypto_instance_ctx(inst));
 	kfree(inst);
 }
 
···
 	.module = THIS_MODULE,
 };
 
+static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key,
+				 unsigned int keylen)
+{
+	struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent);
+	struct crypto_blkcipher *child = ctx->child;
+	int err;
+
+	/* the nonce is stored in bytes at end of key */
+	if (keylen < CTR_RFC3686_NONCE_SIZE)
+		return -EINVAL;
+
+	memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
+	       CTR_RFC3686_NONCE_SIZE);
+
+	keylen -= CTR_RFC3686_NONCE_SIZE;
+
+	crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+	crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
+					  CRYPTO_TFM_REQ_MASK);
+	err = crypto_blkcipher_setkey(child, key, keylen);
+	crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
+				     CRYPTO_TFM_RES_MASK);
+
+	return err;
+}
+
+static int crypto_rfc3686_crypt(struct blkcipher_desc *desc,
+				struct scatterlist *dst,
+				struct scatterlist *src, unsigned int nbytes)
+{
+	struct crypto_blkcipher *tfm = desc->tfm;
+	struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm);
+	struct crypto_blkcipher *child = ctx->child;
+	unsigned long alignmask = crypto_blkcipher_alignmask(tfm);
+	u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask];
+	u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1);
+	u8 *info = desc->info;
+	int err;
+
+	/* set up counter block */
+	memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
+	memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE);
+
+	/* initialize counter portion of counter block */
+	*(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
+		cpu_to_be32(1);
+
+	desc->tfm = child;
+	desc->info = iv;
+	err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes);
+	desc->tfm = tfm;
+	desc->info = info;
+
+	return err;
+}
+
+static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_instance *inst = (void *)tfm->__crt_alg;
+	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
+	struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_blkcipher *cipher;
+
+	cipher = crypto_spawn_blkcipher(spawn);
+	if (IS_ERR(cipher))
+		return PTR_ERR(cipher);
+
+	ctx->child = cipher;
+
+	return 0;
+}
+
+static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_blkcipher(ctx->child);
+}
+
+static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
+{
+	struct crypto_instance *inst;
+	struct crypto_alg *alg;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
+	if (err)
+		return ERR_PTR(err);
+
+	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER,
+				  CRYPTO_ALG_TYPE_MASK);
+	err = PTR_ERR(alg);
+	if (IS_ERR(alg))
+		return ERR_PTR(err);
+
+	/* We only support 16-byte blocks. */
+	err = -EINVAL;
+	if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
+		goto out_put_alg;
+
+	/* Not a stream cipher? */
+	if (alg->cra_blocksize != 1)
+		goto out_put_alg;
+
+	inst = crypto_alloc_instance("rfc3686", alg);
+	if (IS_ERR(inst))
+		goto out;
+
+	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
+	inst->alg.cra_priority = alg->cra_priority;
+	inst->alg.cra_blocksize = 1;
+	inst->alg.cra_alignmask = alg->cra_alignmask;
+	inst->alg.cra_type = &crypto_blkcipher_type;
+
+	inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE;
+	inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize
+					      + CTR_RFC3686_NONCE_SIZE;
+	inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize
+					      + CTR_RFC3686_NONCE_SIZE;
+
+	inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
+
+	inst->alg.cra_init = crypto_rfc3686_init_tfm;
+	inst->alg.cra_exit = crypto_rfc3686_exit_tfm;
+
+	inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey;
+	inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt;
+	inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt;
+
+out:
+	crypto_mod_put(alg);
+	return inst;
+
+out_put_alg:
+	inst = ERR_PTR(err);
+	goto out;
+}
+
+static struct crypto_template crypto_rfc3686_tmpl = {
+	.name = "rfc3686",
+	.alloc = crypto_rfc3686_alloc,
+	.free = crypto_ctr_free,
+	.module = THIS_MODULE,
+};
+
 static int __init crypto_ctr_module_init(void)
 {
-	return crypto_register_template(&crypto_ctr_tmpl);
+	int err;
+
+	err = crypto_register_template(&crypto_ctr_tmpl);
+	if (err)
+		goto out;
+
+	err = crypto_register_template(&crypto_rfc3686_tmpl);
+	if (err)
+		goto out_drop_ctr;
+
+out:
+	return err;
+
+out_drop_ctr:
+	crypto_unregister_template(&crypto_ctr_tmpl);
+	goto out;
 }
 
 static void __exit crypto_ctr_module_exit(void)
 {
+	crypto_unregister_template(&crypto_rfc3686_tmpl);
 	crypto_unregister_template(&crypto_ctr_tmpl);
 }
 
···
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("CTR Counter block mode");
+MODULE_ALIAS("rfc3686");

crypto/gcm.c

···
 
 static inline void crypto_gcm_set_counter(u8 *counterblock, u32 value)
 {
-	*((u32 *)&counterblock[12]) = cpu_to_be32(value);
+	*((u32 *)&counterblock[12]) = cpu_to_be32(value + 1);
 }
 
 static int crypto_gcm_encrypt_counter(struct crypto_aead *aead, u8 *block,
···
 		return inst;
 
 	inst = ERR_PTR(ENAMETOOLONG);
-	if (snprintf(
-		    ctr_name, CRYPTO_MAX_ALG_NAME,
-		    "ctr(%s,0,16,4)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME)
+	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
+		     cipher->cra_name) >= CRYPTO_MAX_ALG_NAME)
 		return inst;
 
 	ctr = crypto_alg_mod_lookup(ctr_name, CRYPTO_ALG_TYPE_BLKCIPHER,

crypto/tcrypt.c

···
 			    AES_XTS_ENC_TEST_VECTORS);
 		test_cipher("xts(aes)", DECRYPT, aes_xts_dec_tv_template,
 			    AES_XTS_DEC_TEST_VECTORS);
-		test_cipher("ctr(aes,4,8,4)", ENCRYPT, aes_ctr_enc_tv_template,
+		test_cipher("rfc3686(ctr(aes))", ENCRYPT, aes_ctr_enc_tv_template,
 			    AES_CTR_ENC_TEST_VECTORS);
-		test_cipher("ctr(aes,4,8,4)", DECRYPT, aes_ctr_dec_tv_template,
+		test_cipher("rfc3686(ctr(aes))", DECRYPT, aes_ctr_dec_tv_template,
 			    AES_CTR_DEC_TEST_VECTORS);
 		test_aead("gcm(aes)", ENCRYPT, aes_gcm_enc_tv_template,
 			  AES_GCM_ENC_TEST_VECTORS);
···
 			    AES_XTS_ENC_TEST_VECTORS);
 		test_cipher("xts(aes)", DECRYPT, aes_xts_dec_tv_template,
 			    AES_XTS_DEC_TEST_VECTORS);
-		test_cipher("ctr(aes,4,8,4)", ENCRYPT, aes_ctr_enc_tv_template,
+		test_cipher("rfc3686(ctr(aes))", ENCRYPT, aes_ctr_enc_tv_template,
 			    AES_CTR_ENC_TEST_VECTORS);
-		test_cipher("ctr(aes,4,8,4)", DECRYPT, aes_ctr_dec_tv_template,
+		test_cipher("rfc3686(ctr(aes))", DECRYPT, aes_ctr_dec_tv_template,
 			    AES_CTR_DEC_TEST_VECTORS);
 		break;
 

include/crypto/ctr.h

···
+/*
+ * CTR: Counter mode
+ *
+ * Copyright (c) 2007 Herbert Xu <[e-mail]>
+ *
+ * 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_CTR_H
+#define _CRYPTO_CTR_H
+
+#define CTR_RFC3686_NONCE_SIZE 4
+#define CTR_RFC3686_IV_SIZE 8
+#define CTR_RFC3686_BLOCK_SIZE 16
+
+#endif  /* _CRYPTO_CTR_H */