1 files changed, 369 insertions, 0 deletions
diff --git a/crypto/ctr.c b/crypto/ctr.c
new file mode 100644
index 00000000000..810d5ec2d5d
--- /dev/null
+++ b/crypto/ctr.c
@@ -0,0 +1,369 @@
+/*
+ * CTR: Counter mode
+ *
+ * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
+ *
+ * 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/random.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+
+struct ctr_instance_ctx {
+	struct crypto_spawn alg;
+	unsigned int noncesize;
+	unsigned int ivsize;
+};
+
+struct crypto_ctr_ctx {
+	struct crypto_cipher *child;
+	u8 *nonce;
+};
+
+static inline void __ctr_inc_byte(u8 *a, unsigned int size)
+{
+	u8 *b = (a + size);
+	u8 c;
+
+	for (; size; size--) {
+		c = *--b + 1;
+		*b = c;
+		if (c)
+			break;
+	}
+}
+
+static void ctr_inc_quad(u8 *a, unsigned int size)
+{
+	__be32 *b = (__be32 *)(a + size);
+	u32 c;
+
+	for (; size >= 4; size -=4) {
+		c = be32_to_cpu(*--b) + 1;
+		*b = cpu_to_be32(c);
+		if (c)
+			return;
+	}
+
+	__ctr_inc_byte(a, size);
+}
+
+static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
+{
+	for (; bs; bs--)
+		*a++ ^= *b++;
+}
+
+static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
+{
+	u32 *a = (u32 *)dst;
+	u32 *b = (u32 *)src;
+
+	for (; bs >= 4; bs -= 4)
+		*a++ ^= *b++;
+
+	xor_byte((u8 *)a, (u8 *)b, bs);
+}
+
+static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
+			     unsigned int keylen)
+{
+	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;
+
+	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_ctr_crypt_segment(struct blkcipher_walk *walk,
+				    struct crypto_cipher *tfm, u8 *ctrblk,
+				    unsigned int countersize)
+{
+	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);
+	u8 ks[bsize + alignmask];
+	u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
+	u8 *src = walk->src.virt.addr;
+	u8 *dst = walk->dst.virt.addr;
+	unsigned int nbytes = walk->nbytes;
+
+	do {
+		/* create keystream */
+		fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
+		xor_quad(keystream, src, min(nbytes, bsize));
+
+		/* copy result into dst */
+		memcpy(dst, keystream, min(nbytes, bsize));
+
+		/* increment counter in counterblock */
+		ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
+
+		if (nbytes < bsize)
+			break;
+
+		src += bsize;
+		dst += bsize;
+		nbytes -= bsize;
+
+	} while (nbytes);
+
+	return 0;
+}
+
+static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
+				    struct crypto_cipher *tfm, u8 *ctrblk,
+				    unsigned int countersize)
+{
+	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 *src = walk->src.virt.addr;
+	u8 ks[bsize + alignmask];
+	u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
+
+	do {
+		/* create keystream */
+		fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
+		xor_quad(src, keystream, min(nbytes, bsize));
+
+		/* increment counter in counterblock */
+		ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
+
+		if (nbytes < bsize)
+			break;
+
+		src += bsize;
+		nbytes -= bsize;
+
+	} while (nbytes);
+
+	return 0;
+}
+
+static int crypto_ctr_crypt(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_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);
+	u8 cblk[bsize + alignmask];
+	u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
+	unsigned int countersize;
+	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 */
+	countersize = bsize - ictx->noncesize - ictx->ivsize;
+	ctr_inc_quad(counterblk + (bsize - countersize), countersize);
+
+	while (walk.nbytes) {
+		if (walk.src.virt.addr == walk.dst.virt.addr)
+			nbytes = crypto_ctr_crypt_inplace(&walk, child,
+							  counterblk,
+							  countersize);
+		else
+			nbytes = crypto_ctr_crypt_segment(&walk, child,
+							  counterblk,
+							  countersize);
+
+		err = blkcipher_walk_done(desc, &walk, nbytes);
+	}
+	return err;
+}
+
+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_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);
+	if (IS_ERR(cipher))
+		return PTR_ERR(cipher);
+
+	ctx->child = cipher;
+
+	return 0;
+}
+
+static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	kfree(ctx->nonce);
+	crypto_free_cipher(ctx->child);
+}
+
+static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
+{
+	struct crypto_instance *inst;
+	struct crypto_alg *alg;
+	struct ctr_instance_ctx *ictx;
+	unsigned int noncesize;
+	unsigned int ivsize;
+	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_CIPHER,
+				  CRYPTO_ALG_TYPE_MASK);
+	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;
+
+	/* verify size of nonce + iv + counter */
+	err = -EINVAL;
+	if ((noncesize + ivsize) >= alg->cra_blocksize)
+		goto out_put_alg;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!inst)
+		goto out_put_alg;
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "ctr(%s,%u,%u)", alg->cra_name, noncesize,
+		     ivsize) >= CRYPTO_MAX_ALG_NAME) {
+		goto err_free_inst;
+	}
+
+	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "ctr(%s,%u,%u)", alg->cra_driver_name, noncesize,
+		     ivsize) >= CRYPTO_MAX_ALG_NAME) {
+		goto err_free_inst;
+	}
+
+	ictx = crypto_instance_ctx(inst);
+	ictx->noncesize = noncesize;
+	ictx->ivsize = ivsize;
+
+	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 = 3;
+	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_ctxsize = sizeof(struct crypto_ctr_ctx);
+
+	inst->alg.cra_init = crypto_ctr_init_tfm;
+	inst->alg.cra_exit = crypto_ctr_exit_tfm;
+
+	inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
+	inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
+	inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
+
+err_free_inst:
+	if (err)
+		kfree(inst);
+
+out_put_alg:
+	crypto_mod_put(alg);
+
+	if (err)
+		inst = ERR_PTR(err);
+
+	return inst;
+}
+
+static void crypto_ctr_free(struct crypto_instance *inst)
+{
+	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
+
+	crypto_drop_spawn(&ictx->alg);
+	kfree(inst);
+}
+
+static struct crypto_template crypto_ctr_tmpl = {
+	.name = "ctr",
+	.alloc = crypto_ctr_alloc,
+	.free = crypto_ctr_free,
+	.module = THIS_MODULE,
+};
+
+static int __init crypto_ctr_module_init(void)
+{
+	return crypto_register_template(&crypto_ctr_tmpl);
+}
+
+static void __exit crypto_ctr_module_exit(void)
+{
+	crypto_unregister_template(&crypto_ctr_tmpl);
+}
+
+module_init(crypto_ctr_module_init);
+module_exit(crypto_ctr_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CTR Counter block mode");