/*
   * RSA padding templates.
   *
   * Copyright (c) 2015  Intel Corporation
   *
   * 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 <crypto/akcipher.h>
  #include <crypto/internal/akcipher.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/random.h>

  /*
   * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
   */
  static const u8 rsa_digest_info_md5[] = {
  	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
  	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
  	0x05, 0x00, 0x04, 0x10
  };
  
  static const u8 rsa_digest_info_sha1[] = {
  	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
  	0x2b, 0x0e, 0x03, 0x02, 0x1a,
  	0x05, 0x00, 0x04, 0x14
  };
  
  static const u8 rsa_digest_info_rmd160[] = {
  	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
  	0x2b, 0x24, 0x03, 0x02, 0x01,
  	0x05, 0x00, 0x04, 0x14
  };
  
  static const u8 rsa_digest_info_sha224[] = {
  	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
  	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
  	0x05, 0x00, 0x04, 0x1c
  };
  
  static const u8 rsa_digest_info_sha256[] = {
  	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
  	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
  	0x05, 0x00, 0x04, 0x20
  };
  
  static const u8 rsa_digest_info_sha384[] = {
  	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
  	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
  	0x05, 0x00, 0x04, 0x30
  };
  
  static const u8 rsa_digest_info_sha512[] = {
  	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
  	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
  	0x05, 0x00, 0x04, 0x40
  };
  
  static const struct rsa_asn1_template {
  	const char	*name;
  	const u8	*data;
  	size_t		size;
  } rsa_asn1_templates[] = {
  #define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
  	_(md5),
  	_(sha1),
  	_(rmd160),
  	_(sha256),
  	_(sha384),
  	_(sha512),
  	_(sha224),
  	{ NULL }
  #undef _
  };
  
  static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
  {
  	const struct rsa_asn1_template *p;
  
  	for (p = rsa_asn1_templates; p->name; p++)
  		if (strcmp(name, p->name) == 0)
  			return p;
  	return NULL;
  }

  struct pkcs1pad_ctx {
  	struct crypto_akcipher *child;

  	unsigned int key_size;
  };

  struct pkcs1pad_inst_ctx {
  	struct crypto_akcipher_spawn spawn;

  	const struct rsa_asn1_template *digest_info;

  };

  struct pkcs1pad_request {

  	struct scatterlist in_sg[2], out_sg[1];

  	uint8_t *in_buf, *out_buf;

  	struct akcipher_request child_req;

  };
  
  static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
  		unsigned int keylen)
  {
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);

  	int err;
  
  	ctx->key_size = 0;

  
  	err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);

  	if (err)
  		return err;

  	/* Find out new modulus size from rsa implementation */
  	err = crypto_akcipher_maxsize(ctx->child);

  	if (err > PAGE_SIZE)
  		return -ENOTSUPP;

  	ctx->key_size = err;
  	return 0;

  }
  
  static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
  		unsigned int keylen)
  {
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);

  	int err;
  
  	ctx->key_size = 0;

  
  	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);

  	if (err)
  		return err;

  	/* Find out new modulus size from rsa implementation */
  	err = crypto_akcipher_maxsize(ctx->child);

  	if (err > PAGE_SIZE)
  		return -ENOTSUPP;

  	ctx->key_size = err;
  	return 0;

  }

  static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)

  {
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  
  	/*
  	 * The maximum destination buffer size for the encrypt/sign operations
  	 * will be the same as for RSA, even though it's smaller for
  	 * decrypt/verify.
  	 */

  	return ctx->key_size;

  }
  
  static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
  		struct scatterlist *next)
  {

  	int nsegs = next ? 2 : 1;
  
  	sg_init_table(sg, nsegs);
  	sg_set_buf(sg, buf, len);

  
  	if (next)
  		sg_chain(sg, nsegs, next);
  }
  
  static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);

  	unsigned int pad_len;
  	unsigned int len;
  	u8 *out_buf;
  
  	if (err)
  		goto out;
  
  	len = req_ctx->child_req.dst_len;
  	pad_len = ctx->key_size - len;
  
  	/* Four billion to one */
  	if (likely(!pad_len))
  		goto out;
  
  	out_buf = kzalloc(ctx->key_size, GFP_ATOMIC);
  	err = -ENOMEM;
  	if (!out_buf)
  		goto out;
  
  	sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
  			  out_buf + pad_len, len);
  	sg_copy_from_buffer(req->dst,
  			    sg_nents_for_len(req->dst, ctx->key_size),
  			    out_buf, ctx->key_size);
  	kzfree(out_buf);
  
  out:

  	req->dst_len = ctx->key_size;
  
  	kfree(req_ctx->in_buf);

  
  	return err;
  }
  
  static void pkcs1pad_encrypt_sign_complete_cb(
  		struct crypto_async_request *child_async_req, int err)
  {
  	struct akcipher_request *req = child_async_req->data;
  	struct crypto_async_request async_req;
  
  	if (err == -EINPROGRESS)
  		return;
  
  	async_req.data = req->base.data;
  	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
  	async_req.flags = child_async_req->flags;
  	req->base.complete(&async_req,
  			pkcs1pad_encrypt_sign_complete(req, err));
  }
  
  static int pkcs1pad_encrypt(struct akcipher_request *req)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
  	int err;
  	unsigned int i, ps_end;
  
  	if (!ctx->key_size)
  		return -EINVAL;
  
  	if (req->src_len > ctx->key_size - 11)
  		return -EOVERFLOW;
  
  	if (req->dst_len < ctx->key_size) {
  		req->dst_len = ctx->key_size;
  		return -EOVERFLOW;
  	}

  	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,

  				  GFP_KERNEL);

  	if (!req_ctx->in_buf)
  		return -ENOMEM;
  
  	ps_end = ctx->key_size - req->src_len - 2;
  	req_ctx->in_buf[0] = 0x02;
  	for (i = 1; i < ps_end; i++)
  		req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
  	req_ctx->in_buf[ps_end] = 0x00;
  
  	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
  			ctx->key_size - 1 - req->src_len, req->src);

  	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);

  	if (!req_ctx->out_buf) {
  		kfree(req_ctx->in_buf);
  		return -ENOMEM;
  	}
  
  	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
  			ctx->key_size, NULL);
  
  	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
  	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
  			pkcs1pad_encrypt_sign_complete_cb, req);

  	/* Reuse output buffer */
  	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
  				   req->dst, ctx->key_size - 1, req->dst_len);

  	err = crypto_akcipher_encrypt(&req_ctx->child_req);
  	if (err != -EINPROGRESS &&
  			(err != -EBUSY ||
  			 !(req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG)))
  		return pkcs1pad_encrypt_sign_complete(req, err);
  
  	return err;
  }
  
  static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);

  	unsigned int dst_len;

  	unsigned int pos;

  	u8 *out_buf;

  
  	if (err)
  		goto done;

  	err = -EINVAL;
  	dst_len = req_ctx->child_req.dst_len;
  	if (dst_len < ctx->key_size - 1)

  		goto done;

  
  	out_buf = req_ctx->out_buf;
  	if (dst_len == ctx->key_size) {
  		if (out_buf[0] != 0x00)
  			/* Decrypted value had no leading 0 byte */
  			goto done;
  
  		dst_len--;
  		out_buf++;

  	}

  	if (out_buf[0] != 0x02)

  		goto done;

  
  	for (pos = 1; pos < dst_len; pos++)
  		if (out_buf[pos] == 0x00)

  			break;

  	if (pos < 9 || pos == dst_len)

  		goto done;

  	pos++;

  	err = 0;
  
  	if (req->dst_len < dst_len - pos)

  		err = -EOVERFLOW;

  	req->dst_len = dst_len - pos;

  
  	if (!err)
  		sg_copy_from_buffer(req->dst,
  				sg_nents_for_len(req->dst, req->dst_len),

  				out_buf + pos, req->dst_len);

  
  done:
  	kzfree(req_ctx->out_buf);
  
  	return err;
  }
  
  static void pkcs1pad_decrypt_complete_cb(
  		struct crypto_async_request *child_async_req, int err)
  {
  	struct akcipher_request *req = child_async_req->data;
  	struct crypto_async_request async_req;
  
  	if (err == -EINPROGRESS)
  		return;
  
  	async_req.data = req->base.data;
  	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
  	async_req.flags = child_async_req->flags;
  	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
  }
  
  static int pkcs1pad_decrypt(struct akcipher_request *req)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
  	int err;
  
  	if (!ctx->key_size || req->src_len != ctx->key_size)
  		return -EINVAL;

  	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);

  	if (!req_ctx->out_buf)
  		return -ENOMEM;
  
  	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,

  			    ctx->key_size, NULL);

  
  	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
  	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
  			pkcs1pad_decrypt_complete_cb, req);

  	/* Reuse input buffer, output to a new buffer */
  	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
  				   req_ctx->out_sg, req->src_len,
  				   ctx->key_size);

  	err = crypto_akcipher_decrypt(&req_ctx->child_req);
  	if (err != -EINPROGRESS &&
  			(err != -EBUSY ||
  			 !(req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG)))
  		return pkcs1pad_decrypt_complete(req, err);
  
  	return err;
  }
  
  static int pkcs1pad_sign(struct akcipher_request *req)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);

  	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
  	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
  	const struct rsa_asn1_template *digest_info = ictx->digest_info;

  	int err;

  	unsigned int ps_end, digest_size = 0;

  
  	if (!ctx->key_size)
  		return -EINVAL;

  	digest_size = digest_info->size;

  
  	if (req->src_len + digest_size > ctx->key_size - 11)

  		return -EOVERFLOW;
  
  	if (req->dst_len < ctx->key_size) {
  		req->dst_len = ctx->key_size;
  		return -EOVERFLOW;
  	}

  	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,

  				  GFP_KERNEL);

  	if (!req_ctx->in_buf)
  		return -ENOMEM;

  	ps_end = ctx->key_size - digest_size - req->src_len - 2;

  	req_ctx->in_buf[0] = 0x01;
  	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
  	req_ctx->in_buf[ps_end] = 0x00;

  	memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
  	       digest_info->size);

  	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
  			ctx->key_size - 1 - req->src_len, req->src);

  	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
  	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
  			pkcs1pad_encrypt_sign_complete_cb, req);

  	/* Reuse output buffer */
  	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
  				   req->dst, ctx->key_size - 1, req->dst_len);

  	err = crypto_akcipher_sign(&req_ctx->child_req);
  	if (err != -EINPROGRESS &&
  			(err != -EBUSY ||
  			 !(req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG)))
  		return pkcs1pad_encrypt_sign_complete(req, err);
  
  	return err;
  }
  
  static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);

  	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
  	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
  	const struct rsa_asn1_template *digest_info = ictx->digest_info;

  	unsigned int dst_len;

  	unsigned int pos;

  	u8 *out_buf;

  
  	if (err)
  		goto done;

  	err = -EINVAL;
  	dst_len = req_ctx->child_req.dst_len;
  	if (dst_len < ctx->key_size - 1)

  		goto done;

  
  	out_buf = req_ctx->out_buf;
  	if (dst_len == ctx->key_size) {
  		if (out_buf[0] != 0x00)
  			/* Decrypted value had no leading 0 byte */
  			goto done;
  
  		dst_len--;
  		out_buf++;

  	}

  	err = -EBADMSG;

  	if (out_buf[0] != 0x01)

  		goto done;

  	for (pos = 1; pos < dst_len; pos++)
  		if (out_buf[pos] != 0xff)

  			break;

  	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)

  		goto done;

  	pos++;

  	if (crypto_memneq(out_buf + pos, digest_info->data, digest_info->size))

  		goto done;

  	pos += digest_info->size;

  
  	err = 0;

  	if (req->dst_len < dst_len - pos)

  		err = -EOVERFLOW;

  	req->dst_len = dst_len - pos;

  
  	if (!err)
  		sg_copy_from_buffer(req->dst,
  				sg_nents_for_len(req->dst, req->dst_len),

  				out_buf + pos, req->dst_len);

  done:
  	kzfree(req_ctx->out_buf);
  
  	return err;
  }
  
  static void pkcs1pad_verify_complete_cb(
  		struct crypto_async_request *child_async_req, int err)
  {
  	struct akcipher_request *req = child_async_req->data;
  	struct crypto_async_request async_req;
  
  	if (err == -EINPROGRESS)
  		return;
  
  	async_req.data = req->base.data;
  	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
  	async_req.flags = child_async_req->flags;
  	req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
  }
  
  /*
   * The verify operation is here for completeness similar to the verification
   * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
   * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
   * retrieve the DigestInfo from a signature, instead the user is expected
   * to call the sign operation to generate the expected signature and compare
   * signatures instead of the message-digests.
   */
  static int pkcs1pad_verify(struct akcipher_request *req)
  {
  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
  	int err;

  	if (!ctx->key_size || req->src_len < ctx->key_size)

  		return -EINVAL;

  	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);

  	if (!req_ctx->out_buf)
  		return -ENOMEM;
  
  	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,

  			    ctx->key_size, NULL);

  
  	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
  	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
  			pkcs1pad_verify_complete_cb, req);

  	/* Reuse input buffer, output to a new buffer */
  	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
  				   req_ctx->out_sg, req->src_len,
  				   ctx->key_size);

  	err = crypto_akcipher_verify(&req_ctx->child_req);
  	if (err != -EINPROGRESS &&
  			(err != -EBUSY ||
  			 !(req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG)))
  		return pkcs1pad_verify_complete(req, err);
  
  	return err;
  }
  
  static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
  {
  	struct akcipher_instance *inst = akcipher_alg_instance(tfm);

  	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);

  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  	struct crypto_akcipher *child_tfm;

  	child_tfm = crypto_spawn_akcipher(&ictx->spawn);

  	if (IS_ERR(child_tfm))
  		return PTR_ERR(child_tfm);
  
  	ctx->child = child_tfm;

  	return 0;
  }
  
  static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
  {
  	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
  
  	crypto_free_akcipher(ctx->child);
  }
  
  static void pkcs1pad_free(struct akcipher_instance *inst)
  {

  	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
  	struct crypto_akcipher_spawn *spawn = &ctx->spawn;

  
  	crypto_drop_akcipher(spawn);

  	kfree(inst);
  }
  
  static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
  {

  	const struct rsa_asn1_template *digest_info;

  	struct crypto_attr_type *algt;
  	struct akcipher_instance *inst;

  	struct pkcs1pad_inst_ctx *ctx;

  	struct crypto_akcipher_spawn *spawn;
  	struct akcipher_alg *rsa_alg;
  	const char *rsa_alg_name;

  	const char *hash_name;

  	int err;
  
  	algt = crypto_get_attr_type(tb);
  	if (IS_ERR(algt))
  		return PTR_ERR(algt);
  
  	if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
  		return -EINVAL;
  
  	rsa_alg_name = crypto_attr_alg_name(tb[1]);
  	if (IS_ERR(rsa_alg_name))
  		return PTR_ERR(rsa_alg_name);

  	hash_name = crypto_attr_alg_name(tb[2]);
  	if (IS_ERR(hash_name))

  		return PTR_ERR(hash_name);
  
  	digest_info = rsa_lookup_asn1(hash_name);
  	if (!digest_info)
  		return -EINVAL;

  
  	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);

  	if (!inst)
  		return -ENOMEM;

  	ctx = akcipher_instance_ctx(inst);
  	spawn = &ctx->spawn;

  	ctx->digest_info = digest_info;

  	crypto_set_spawn(&spawn->base, akcipher_crypto_instance(inst));
  	err = crypto_grab_akcipher(spawn, rsa_alg_name, 0,
  			crypto_requires_sync(algt->type, algt->mask));
  	if (err)
  		goto out_free_inst;
  
  	rsa_alg = crypto_spawn_akcipher_alg(spawn);
  
  	err = -ENAMETOOLONG;

  	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
  		     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name, hash_name) >=
  	    CRYPTO_MAX_ALG_NAME ||
  	    snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "pkcs1pad(%s,%s)",
  		     rsa_alg->base.cra_driver_name, hash_name) >=
  	    CRYPTO_MAX_ALG_NAME)

  		goto out_drop_alg;
  
  	inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
  	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
  	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
  
  	inst->alg.init = pkcs1pad_init_tfm;
  	inst->alg.exit = pkcs1pad_exit_tfm;
  
  	inst->alg.encrypt = pkcs1pad_encrypt;
  	inst->alg.decrypt = pkcs1pad_decrypt;
  	inst->alg.sign = pkcs1pad_sign;
  	inst->alg.verify = pkcs1pad_verify;
  	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
  	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
  	inst->alg.max_size = pkcs1pad_get_max_size;
  	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
  
  	inst->free = pkcs1pad_free;
  
  	err = akcipher_register_instance(tmpl, inst);
  	if (err)

  		goto out_drop_alg;

  
  	return 0;
  
  out_drop_alg:
  	crypto_drop_akcipher(spawn);
  out_free_inst:
  	kfree(inst);
  	return err;
  }
  
  struct crypto_template rsa_pkcs1pad_tmpl = {
  	.name = "pkcs1pad",
  	.create = pkcs1pad_create,
  	.module = THIS_MODULE,
  };