Re: [PATCH v5] ima_fs: Avoid creating measurement lists for unsupported hash algos

[Mimi Zohar <zohar@linux.ibm.com>]

On Mon, 2026-02-23 at 14:56 +0000, Dmitry Safonov via B4 Relay wrote:
> From: Dmitry Safonov <dima@arista.com>
> 
> ima_tpm_chip->allocated_banks[i].crypto_id is initialized to
> HASH_ALGO__LAST if the TPM algorithm is not supported. However there
> are places relying on the algorithm to be valid because it is accessed
> by hash_algo_name[].

If the TPM algorithm is not supported by whom? the kernel?  HASH_ALGO__LAST is
defined in linux/hash_info.h.  If the crypto algorithm is not supported by the
kernel, then the kernel won't be able to calculate the hash to extend the TPM.

> @@ -404,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void)
>  		char file_name[NAME_MAX + 1];
>  		struct dentry *dentry;
>  
> -		sprintf(file_name, "ascii_runtime_measurements_%s",
> -			hash_algo_name[algo]);
> +		if (algo == HASH_ALGO__LAST)
> +			sprintf(file_name, "ascii_runtime_measurements_tpm_alg_%x",
> +				ima_tpm_chip->allocated_banks[i].alg_id);
> +		else
> +			sprintf(file_name, "ascii_runtime_measurements_%s",
> +				hash_algo_name[algo]);
>  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
>  						ima_dir, (void *)(uintptr_t)i,
>  						&ima_ascii_measurements_ops);
>  		if (IS_ERR(dentry))
>  			return PTR_ERR(dentry);
>  
> -		sprintf(file_name, "binary_runtime_measurements_%s",
> -			hash_algo_name[algo]);
> +		if (algo == HASH_ALGO__LAST)
> +			sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x",
> +				ima_tpm_chip->allocated_banks[i].alg_id);

There's no point in creating either of the securityfs files if the kernel
doesn't support the hash algorithm.

Mimi


> +		else
> +			sprintf(file_name, "binary_runtime_measurements_%s",
> +				hash_algo_name[algo]);
>  		dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
>  						ima_dir, (void *)(uintptr_t)i,
>  						&ima_measurements_ops);