1 files changed, 360 insertions, 0 deletions
diff --git a/crypto/ctr.c b/crypto/ctr.c
new file mode 100644
index 000000000..c39fcffba
--- /dev/null
+++ b/crypto/ctr.c
@@ -0,0 +1,360 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * CTR: Counter mode
+ *
+ * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/ctr.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>
+
+struct crypto_rfc3686_ctx {
+	struct crypto_skcipher *child;
+	u8 nonce[CTR_RFC3686_NONCE_SIZE];
+};
+
+struct crypto_rfc3686_req_ctx {
+	u8 iv[CTR_RFC3686_BLOCK_SIZE];
+	struct skcipher_request subreq CRYPTO_MINALIGN_ATTR;
+};
+
+static void crypto_ctr_crypt_final(struct skcipher_walk *walk,
+				   struct crypto_cipher *tfm)
+{
+	unsigned int bsize = crypto_cipher_blocksize(tfm);
+	unsigned long alignmask = crypto_cipher_alignmask(tfm);
+	u8 *ctrblk = walk->iv;
+	u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_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_cpy(dst, keystream, src, nbytes);
+
+	crypto_inc(ctrblk, bsize);
+}
+
+static int crypto_ctr_crypt_segment(struct skcipher_walk *walk,
+				    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;
+
+	do {
+		/* create keystream */
+		fn(crypto_cipher_tfm(tfm), dst, ctrblk);
+		crypto_xor(dst, src, bsize);
+
+		/* increment counter in counterblock */
+		crypto_inc(ctrblk, bsize);
+
+		src += bsize;
+		dst += bsize;
+	} while ((nbytes -= bsize) >= bsize);
+
+	return nbytes;
+}
+
+static int crypto_ctr_crypt_inplace(struct skcipher_walk *walk,
+				    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 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
+	u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
+
+	do {
+		/* create keystream */
+		fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
+		crypto_xor(src, keystream, bsize);
+
+		/* increment counter in counterblock */
+		crypto_inc(ctrblk, bsize);
+
+		src += bsize;
+	} while ((nbytes -= bsize) >= bsize);
+
+	return nbytes;
+}
+
+static int crypto_ctr_crypt(struct skcipher_request *req)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
+	const unsigned int bsize = crypto_cipher_blocksize(cipher);
+	struct skcipher_walk walk;
+	unsigned int nbytes;
+	int err;
+
+	err = skcipher_walk_virt(&walk, req, false);
+
+	while (walk.nbytes >= bsize) {
+		if (walk.src.virt.addr == walk.dst.virt.addr)
+			nbytes = crypto_ctr_crypt_inplace(&walk, cipher);
+		else
+			nbytes = crypto_ctr_crypt_segment(&walk, cipher);
+
+		err = skcipher_walk_done(&walk, nbytes);
+	}
+
+	if (walk.nbytes) {
+		crypto_ctr_crypt_final(&walk, cipher);
+		err = skcipher_walk_done(&walk, 0);
+	}
+
+	return err;
+}
+
+static int crypto_ctr_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);
+
+	/* Block size must be >= 4 bytes. */
+	err = -EINVAL;
+	if (alg->cra_blocksize < 4)
+		goto out_free_inst;
+
+	/* If this is false we'd fail the alignment of crypto_inc. */
+	if (alg->cra_blocksize % 4)
+		goto out_free_inst;
+
+	/* CTR 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_ctr_crypt;
+	inst->alg.decrypt = crypto_ctr_crypt;
+
+	err = skcipher_register_instance(tmpl, inst);
+	if (err) {
+out_free_inst:
+		inst->free(inst);
+	}
+
+	return err;
+}
+
+static int crypto_rfc3686_setkey(struct crypto_skcipher *parent,
+				 const u8 *key, unsigned int keylen)
+{
+	struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent);
+	struct crypto_skcipher *child = ctx->child;
+
+	/* 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_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
+					 CRYPTO_TFM_REQ_MASK);
+	return crypto_skcipher_setkey(child, key, keylen);
+}
+
+static int crypto_rfc3686_crypt(struct skcipher_request *req)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct crypto_skcipher *child = ctx->child;
+	unsigned long align = crypto_skcipher_alignmask(tfm);
+	struct crypto_rfc3686_req_ctx *rctx =
+		(void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1);
+	struct skcipher_request *subreq = &rctx->subreq;
+	u8 *iv = rctx->iv;
+
+	/* set up counter block */
+	memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
+	memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE);
+
+	/* initialize counter portion of counter block */
+	*(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
+		cpu_to_be32(1);
+
+	skcipher_request_set_tfm(subreq, child);
+	skcipher_request_set_callback(subreq, req->base.flags,
+				      req->base.complete, req->base.data);
+	skcipher_request_set_crypt(subreq, req->src, req->dst,
+				   req->cryptlen, iv);
+
+	return crypto_skcipher_encrypt(subreq);
+}
+
+static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm)
+{
+	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+	struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
+	struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct crypto_skcipher *cipher;
+	unsigned long align;
+	unsigned int reqsize;
+
+	cipher = crypto_spawn_skcipher(spawn);
+	if (IS_ERR(cipher))
+		return PTR_ERR(cipher);
+
+	ctx->child = cipher;
+
+	align = crypto_skcipher_alignmask(tfm);
+	align &= ~(crypto_tfm_ctx_alignment() - 1);
+	reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) +
+		  crypto_skcipher_reqsize(cipher);
+	crypto_skcipher_set_reqsize(tfm, reqsize);
+
+	return 0;
+}
+
+static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm)
+{
+	struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+	crypto_free_skcipher(ctx->child);
+}
+
+static void crypto_rfc3686_free(struct skcipher_instance *inst)
+{
+	struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
+
+	crypto_drop_skcipher(spawn);
+	kfree(inst);
+}
+
+static int crypto_rfc3686_create(struct crypto_template *tmpl,
+				 struct rtattr **tb)
+{
+	struct skcipher_instance *inst;
+	struct skcipher_alg *alg;
+	struct crypto_skcipher_spawn *spawn;
+	u32 mask;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
+	if (err)
+		return err;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+
+	spawn = skcipher_instance_ctx(inst);
+
+	err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst),
+				   crypto_attr_alg_name(tb[1]), 0, mask);
+	if (err)
+		goto err_free_inst;
+
+	alg = crypto_spawn_skcipher_alg(spawn);
+
+	/* We only support 16-byte blocks. */
+	err = -EINVAL;
+	if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE)
+		goto err_free_inst;
+
+	/* Not a stream cipher? */
+	if (alg->base.cra_blocksize != 1)
+		goto err_free_inst;
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "rfc3686(%s)", alg->base.cra_driver_name) >=
+	    CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+
+	inst->alg.base.cra_priority = alg->base.cra_priority;
+	inst->alg.base.cra_blocksize = 1;
+	inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
+
+	inst->alg.ivsize = CTR_RFC3686_IV_SIZE;
+	inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg);
+	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
+				CTR_RFC3686_NONCE_SIZE;
+	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
+				CTR_RFC3686_NONCE_SIZE;
+
+	inst->alg.setkey = crypto_rfc3686_setkey;
+	inst->alg.encrypt = crypto_rfc3686_crypt;
+	inst->alg.decrypt = crypto_rfc3686_crypt;
+
+	inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
+
+	inst->alg.init = crypto_rfc3686_init_tfm;
+	inst->alg.exit = crypto_rfc3686_exit_tfm;
+
+	inst->free = crypto_rfc3686_free;
+
+	err = skcipher_register_instance(tmpl, inst);
+	if (err) {
+err_free_inst:
+		crypto_rfc3686_free(inst);
+	}
+	return err;
+}
+
+static struct crypto_template crypto_ctr_tmpls[] = {
+	{
+		.name = "ctr",
+		.create = crypto_ctr_create,
+		.module = THIS_MODULE,
+	}, {
+		.name = "rfc3686",
+		.create = crypto_rfc3686_create,
+		.module = THIS_MODULE,
+	},
+};
+
+static int __init crypto_ctr_module_init(void)
+{
+	return crypto_register_templates(crypto_ctr_tmpls,
+					 ARRAY_SIZE(crypto_ctr_tmpls));
+}
+
+static void __exit crypto_ctr_module_exit(void)
+{
+	crypto_unregister_templates(crypto_ctr_tmpls,
+				    ARRAY_SIZE(crypto_ctr_tmpls));
+}
+
+subsys_initcall(crypto_ctr_module_init);
+module_exit(crypto_ctr_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CTR block cipher mode of operation");
+MODULE_ALIAS_CRYPTO("rfc3686");
+MODULE_ALIAS_CRYPTO("ctr");