Re: [PATCH v11 1/9] ima: rename variable the set_file "file" to "ima_kexec_file"

[Baoquan He <bhe@redhat.com>]

On 04/02/25 at 05:47am, steven chen wrote:
> The current kernel behavior is IMA measurements snapshot is taken at
> kexec 'load' and not at kexec 'execute'. IMA log is then carried
> over to the new kernel after kexec 'execute'. However, the time gap
> between kexec load and kexec reboot can be very long. During this
> time window, new events extended into TPM PCRs miss the chance
> to be carried over to the second kernel.
>  
> To address the above, the following approach is proposed:
>   - Allocate the necessary buffer during the kexec load phase.
>   - Populate this buffer with the IMA measurements during
>     the kexec execute phase.
> 
> In the current implementation, a local variable "file" of type seq_file
> is used in the API ima_dump_measurement_list() to store the IMA measurements
> to be carried over across kexec system call. To make this buffer accessible
> at kexec 'execute' time, rename it to "ima_kexec_file" before making it
> a file variable to better reflect its purpose.
> 
> Renaming the local variable "file" of type seq_file defined in the 
> ima_dump_measurement_list function to "ima_kexec_file" will improve code
> readability and maintainability by making the variable's role more explicit.

Seems it's clearer with below paragraph to replace the whole log:

=====
Rename the local variable "file" of type seq_file defined in the 
ima_dump_measurement_list function to "ima_kexec_file" to improve code
readability and maintainability by making the variable's role more explicit.
=====

The code change looks good to me.


> 
> Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
> Signed-off-by: steven chen <chenste@linux.microsoft.com>
> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>

If there's code change in patch content, the reviewing tag should be
reset so that reviewing is taken again on the new change.

> ---
>  security/integrity/ima/ima_kexec.c | 31 +++++++++++++++---------------
>  1 file changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
> index 9d45f4d26f73..650beb74346c 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -18,30 +18,30 @@
>  static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
>  				     unsigned long segment_size)
>  {
> +	struct seq_file ima_kexec_file;
>  	struct ima_queue_entry *qe;
> -	struct seq_file file;
>  	struct ima_kexec_hdr khdr;
>  	int ret = 0;
>  
>  	/* segment size can't change between kexec load and execute */
> -	file.buf = vmalloc(segment_size);
> -	if (!file.buf) {
> +	ima_kexec_file.buf = vmalloc(segment_size);
> +	if (!ima_kexec_file.buf) {
>  		ret = -ENOMEM;
>  		goto out;
>  	}
>  
> -	file.file = NULL;
> -	file.size = segment_size;
> -	file.read_pos = 0;
> -	file.count = sizeof(khdr);	/* reserved space */
> +	ima_kexec_file.file = NULL;
> +	ima_kexec_file.size = segment_size;
> +	ima_kexec_file.read_pos = 0;
> +	ima_kexec_file.count = sizeof(khdr);	/* reserved space */
>  
>  	memset(&khdr, 0, sizeof(khdr));
>  	khdr.version = 1;
>  	/* This is an append-only list, no need to hold the RCU read lock */
>  	list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
> -		if (file.count < file.size) {
> +		if (ima_kexec_file.count < ima_kexec_file.size) {
>  			khdr.count++;
> -			ima_measurements_show(&file, qe);
> +			ima_measurements_show(&ima_kexec_file, qe);
>  		} else {
>  			ret = -EINVAL;
>  			break;
> @@ -55,23 +55,24 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
>  	 * fill in reserved space with some buffer details
>  	 * (eg. version, buffer size, number of measurements)
>  	 */
> -	khdr.buffer_size = file.count;
> +	khdr.buffer_size = ima_kexec_file.count;
>  	if (ima_canonical_fmt) {
>  		khdr.version = cpu_to_le16(khdr.version);
>  		khdr.count = cpu_to_le64(khdr.count);
>  		khdr.buffer_size = cpu_to_le64(khdr.buffer_size);
>  	}
> -	memcpy(file.buf, &khdr, sizeof(khdr));
> +	memcpy(ima_kexec_file.buf, &khdr, sizeof(khdr));
>  
>  	print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1,
> -			     file.buf, file.count < 100 ? file.count : 100,
> +			     ima_kexec_file.buf, ima_kexec_file.count < 100 ?
> +			     ima_kexec_file.count : 100,
>  			     true);
>  
> -	*buffer_size = file.count;
> -	*buffer = file.buf;
> +	*buffer_size = ima_kexec_file.count;
> +	*buffer = ima_kexec_file.buf;
>  out:
>  	if (ret == -EINVAL)
> -		vfree(file.buf);
> +		vfree(ima_kexec_file.buf);
>  	return ret;
>  }
>  
> -- 
> 2.25.1
>