text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Cryptographic API.
   *
   * Copyright (c) 2013 Chanho Min <chanho.min@lge.com>
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/crypto.h>
  #include <linux/vmalloc.h>
  #include <linux/lz4.h>
  #include <crypto/internal/scompress.h>
  
  struct lz4_ctx {
  	void *lz4_comp_mem;
  };
  
  static void *lz4_alloc_ctx(struct crypto_scomp *tfm)
  {
  	void *ctx;
  
  	ctx = vmalloc(LZ4_MEM_COMPRESS);
  	if (!ctx)
  		return ERR_PTR(-ENOMEM);
  
  	return ctx;
  }
  
  static int lz4_init(struct crypto_tfm *tfm)
  {
  	struct lz4_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	ctx->lz4_comp_mem = lz4_alloc_ctx(NULL);
  	if (IS_ERR(ctx->lz4_comp_mem))
  		return -ENOMEM;
  
  	return 0;
  }
  
  static void lz4_free_ctx(struct crypto_scomp *tfm, void *ctx)
  {
  	vfree(ctx);
  }
  
  static void lz4_exit(struct crypto_tfm *tfm)
  {
  	struct lz4_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	lz4_free_ctx(NULL, ctx->lz4_comp_mem);
  }
  
  static int __lz4_compress_crypto(const u8 *src, unsigned int slen,
  				 u8 *dst, unsigned int *dlen, void *ctx)
  {
  	int out_len = LZ4_compress_default(src, dst,
  		slen, *dlen, ctx);
  
  	if (!out_len)
  		return -EINVAL;
  
  	*dlen = out_len;
  	return 0;
  }
  
  static int lz4_scompress(struct crypto_scomp *tfm, const u8 *src,
  			 unsigned int slen, u8 *dst, unsigned int *dlen,
  			 void *ctx)
  {
  	return __lz4_compress_crypto(src, slen, dst, dlen, ctx);
  }
  
  static int lz4_compress_crypto(struct crypto_tfm *tfm, const u8 *src,
  			       unsigned int slen, u8 *dst, unsigned int *dlen)
  {
  	struct lz4_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	return __lz4_compress_crypto(src, slen, dst, dlen, ctx->lz4_comp_mem);
  }
  
  static int __lz4_decompress_crypto(const u8 *src, unsigned int slen,
  				   u8 *dst, unsigned int *dlen, void *ctx)
  {
  	int out_len = LZ4_decompress_safe(src, dst, slen, *dlen);
  
  	if (out_len < 0)
  		return -EINVAL;
  
  	*dlen = out_len;
  	return 0;
  }
  
  static int lz4_sdecompress(struct crypto_scomp *tfm, const u8 *src,
  			   unsigned int slen, u8 *dst, unsigned int *dlen,
  			   void *ctx)
  {
  	return __lz4_decompress_crypto(src, slen, dst, dlen, NULL);
  }
  
  static int lz4_decompress_crypto(struct crypto_tfm *tfm, const u8 *src,
  				 unsigned int slen, u8 *dst,
  				 unsigned int *dlen)
  {
  	return __lz4_decompress_crypto(src, slen, dst, dlen, NULL);
  }
  
  static struct crypto_alg alg_lz4 = {
  	.cra_name		= "lz4",
  	.cra_driver_name	= "lz4-generic",
  	.cra_flags		= CRYPTO_ALG_TYPE_COMPRESS,
  	.cra_ctxsize		= sizeof(struct lz4_ctx),
  	.cra_module		= THIS_MODULE,
  	.cra_init		= lz4_init,
  	.cra_exit		= lz4_exit,
  	.cra_u			= { .compress = {
  	.coa_compress		= lz4_compress_crypto,
  	.coa_decompress		= lz4_decompress_crypto } }
  };
  
  static struct scomp_alg scomp = {
  	.alloc_ctx		= lz4_alloc_ctx,
  	.free_ctx		= lz4_free_ctx,
  	.compress		= lz4_scompress,
  	.decompress		= lz4_sdecompress,
  	.base			= {
  		.cra_name	= "lz4",
  		.cra_driver_name = "lz4-scomp",
  		.cra_module	 = THIS_MODULE,
  	}
  };
  
  static int __init lz4_mod_init(void)
  {
  	int ret;
  
  	ret = crypto_register_alg(&alg_lz4);
  	if (ret)
  		return ret;
  
  	ret = crypto_register_scomp(&scomp);
  	if (ret) {
  		crypto_unregister_alg(&alg_lz4);
  		return ret;
  	}
  
  	return ret;
  }
  
  static void __exit lz4_mod_fini(void)
  {
  	crypto_unregister_alg(&alg_lz4);
  	crypto_unregister_scomp(&scomp);
  }
  
  subsys_initcall(lz4_mod_init);
  module_exit(lz4_mod_fini);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("LZ4 Compression Algorithm");
  MODULE_ALIAS_CRYPTO("lz4");
  