linux-kernel - Re: [PATCH] tee: Use SHA-1 library instead of crypto

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Message-ID: <aJmKDyD4weX9bR0U@sumit-X1>
Date: Mon, 11 Aug 2025 11:43:35 +0530
From: Sumit Garg <sumit.garg@...nel.org>
To: Eric Biggers <ebiggers@...nel.org>
Cc: Jens Wiklander <jens.wiklander@...aro.org>,
	op-tee@...ts.trustedfirmware.org, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tee: Use SHA-1 library instead of crypto_shash

On Fri, Aug 01, 2025 at 04:55:41PM -0700, Eric Biggers wrote:
> Use the SHA-1 library functions instead of crypto_shash.  This is
> simpler and faster.
> 
> Change uuid_v5() to return void, since it can no longer fail.
> 
> Signed-off-by: Eric Biggers <ebiggers@...nel.org>
> ---
> 
> Note: this patch depends on the SHA-1 library functions that were merged
> in v6.17-rc1.
> 
>  drivers/tee/Kconfig    |  3 +--
>  drivers/tee/tee_core.c | 55 +++++++-----------------------------------
>  2 files changed, 10 insertions(+), 48 deletions(-)

Nice cleanup, FWIW:

Reviewed-by: Sumit Garg <sumit.garg@....qualcomm.com>

-Sumit

> 
> diff --git a/drivers/tee/Kconfig b/drivers/tee/Kconfig
> index 61b507c187801..a84767940fbfc 100644
> --- a/drivers/tee/Kconfig
> +++ b/drivers/tee/Kconfig
> @@ -1,12 +1,11 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  # Generic Trusted Execution Environment Configuration
>  menuconfig TEE
>  	tristate "Trusted Execution Environment support"
>  	depends on HAVE_ARM_SMCCC || COMPILE_TEST || CPU_SUP_AMD
> -	select CRYPTO
> -	select CRYPTO_SHA1
> +	select CRYPTO_LIB_SHA1
>  	select DMA_SHARED_BUFFER
>  	select GENERIC_ALLOCATOR
>  	help
>  	  This implements a generic interface towards a Trusted Execution
>  	  Environment (TEE).
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index acc7998758ad8..d079aeee0690a 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -12,11 +12,10 @@
>  #include <linux/module.h>
>  #include <linux/overflow.h>
>  #include <linux/slab.h>
>  #include <linux/tee_core.h>
>  #include <linux/uaccess.h>
> -#include <crypto/hash.h>
>  #include <crypto/sha1.h>
>  #include "tee_private.h"
>  
>  #define TEE_NUM_DEVICES	32
>  
> @@ -140,72 +139,36 @@ static int tee_release(struct inode *inode, struct file *filp)
>   * UUIDv5 is specific in RFC 4122.
>   *
>   * This implements section (for SHA-1):
>   * 4.3.  Algorithm for Creating a Name-Based UUID
>   */
> -static int uuid_v5(uuid_t *uuid, const uuid_t *ns, const void *name,
> -		   size_t size)
> +static void uuid_v5(uuid_t *uuid, const uuid_t *ns, const void *name,
> +		    size_t size)
>  {
>  	unsigned char hash[SHA1_DIGEST_SIZE];
> -	struct crypto_shash *shash = NULL;
> -	struct shash_desc *desc = NULL;
> -	int rc;
> -
> -	shash = crypto_alloc_shash("sha1", 0, 0);
> -	if (IS_ERR(shash)) {
> -		rc = PTR_ERR(shash);
> -		pr_err("shash(sha1) allocation failed\n");
> -		return rc;
> -	}
> -
> -	desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
> -		       GFP_KERNEL);
> -	if (!desc) {
> -		rc = -ENOMEM;
> -		goto out_free_shash;
> -	}
> -
> -	desc->tfm = shash;
> +	struct sha1_ctx ctx;
>  
> -	rc = crypto_shash_init(desc);
> -	if (rc < 0)
> -		goto out_free_desc;
> -
> -	rc = crypto_shash_update(desc, (const u8 *)ns, sizeof(*ns));
> -	if (rc < 0)
> -		goto out_free_desc;
> -
> -	rc = crypto_shash_update(desc, (const u8 *)name, size);
> -	if (rc < 0)
> -		goto out_free_desc;
> -
> -	rc = crypto_shash_final(desc, hash);
> -	if (rc < 0)
> -		goto out_free_desc;
> +	sha1_init(&ctx);
> +	sha1_update(&ctx, (const u8 *)ns, sizeof(*ns));
> +	sha1_update(&ctx, (const u8 *)name, size);
> +	sha1_final(&ctx, hash);
>  
>  	memcpy(uuid->b, hash, UUID_SIZE);
>  
>  	/* Tag for version 5 */
>  	uuid->b[6] = (hash[6] & 0x0F) | 0x50;
>  	uuid->b[8] = (hash[8] & 0x3F) | 0x80;
> -
> -out_free_desc:
> -	kfree(desc);
> -
> -out_free_shash:
> -	crypto_free_shash(shash);
> -	return rc;
>  }
>  
>  int tee_session_calc_client_uuid(uuid_t *uuid, u32 connection_method,
>  				 const u8 connection_data[TEE_IOCTL_UUID_LEN])
>  {
>  	gid_t ns_grp = (gid_t)-1;
>  	kgid_t grp = INVALID_GID;
>  	char *name = NULL;
>  	int name_len;
> -	int rc;
> +	int rc = 0;
>  
>  	if (connection_method == TEE_IOCTL_LOGIN_PUBLIC ||
>  	    connection_method == TEE_IOCTL_LOGIN_REE_KERNEL) {
>  		/* Nil UUID to be passed to TEE environment */
>  		uuid_copy(uuid, &uuid_null);
> @@ -258,11 +221,11 @@ int tee_session_calc_client_uuid(uuid_t *uuid, u32 connection_method,
>  	default:
>  		rc = -EINVAL;
>  		goto out_free_name;
>  	}
>  
> -	rc = uuid_v5(uuid, &tee_client_uuid_ns, name, name_len);
> +	uuid_v5(uuid, &tee_client_uuid_ns, name, name_len);
>  out_free_name:
>  	kfree(name);
>  
>  	return rc;
>  }
> 
> base-commit: 0905809b38bda1fa0b206986c44d846e46f13c1d
> -- 
> 2.50.1
>