linux-kernel - Re: [PATCH v13 7/9] ima: verify if the segment size has changed

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Message-ID: <089d0ec8-22b0-447a-be2d-f46dc3ecdb43@linux.ibm.com>
Date: Tue, 29 Apr 2025 14:19:46 -0400
From: Stefan Berger <stefanb@...ux.ibm.com>
To: steven chen <chenste@...ux.microsoft.com>, zohar@...ux.ibm.com,
        roberto.sassu@...weicloud.com, roberto.sassu@...wei.com,
        eric.snowberg@...cle.com, ebiederm@...ssion.com, paul@...l-moore.com,
        code@...icks.com, bauermann@...abnow.com,
        linux-integrity@...r.kernel.org, kexec@...ts.infradead.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: madvenka@...ux.microsoft.com, nramas@...ux.microsoft.com,
        James.Bottomley@...senPartnership.com, bhe@...hat.com,
        vgoyal@...hat.com, dyoung@...hat.com
Subject: Re: [PATCH v13 7/9] ima: verify if the segment size has changed



On 4/21/25 6:25 PM, steven chen wrote:
> From: Steven Chen <chenste@...ux.microsoft.com>
> 
> kexec 'load' may be called multiple times. Free and realloc the buffer
> only if the segment_size is changed from the previous kexec 'load' call.
> 
> Signed-off-by: Steven Chen <chenste@...ux.microsoft.com>
> Acked-by: Baoquan He <bhe@...hat.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> ---
>   security/integrity/ima/ima_kexec.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
> index 5c3b3e0b2186..ed867734ee70 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -33,6 +33,14 @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
>   
>   static int ima_alloc_kexec_file_buf(size_t segment_size)
>   {
> +	/*
> +	 * kexec 'load' may be called multiple times.
> +	 * Free and realloc the buffer only if the segment_size is
> +	 * changed from the previous kexec 'load' call.
> +	 */
> +	if (ima_kexec_file.buf && ima_kexec_file.size == segment_size)
> +		goto out;
> +
>   	ima_free_kexec_file_buf(&ima_kexec_file);
>   
>   	/* segment size can't change between kexec load and execute */
> @@ -41,6 +49,8 @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
>   		return -ENOMEM;
>   
>   	ima_kexec_file.size = segment_size;
> +
> +out:
>   	ima_kexec_file.read_pos = 0;
>   	ima_kexec_file.count = sizeof(struct ima_kexec_hdr);	/* reserved space */
>   

Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>