linux-kernel - Re: [PATCH 3/4] ima: limit including fs-verity's file digest in measurement list

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Date:   Mon, 29 Nov 2021 18:35:05 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org, linux-fscrypt@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] ima: limit including fs-verity's file digest in
 measurement list

On Mon, Nov 29, 2021 at 12:00:56PM -0500, Mimi Zohar wrote:
> Without the file signature included the IMA measurement list, the type
> of file digest is unclear.  Limit including fs-verity's file digest in
> the IMA measurement list based on whether the template name is ima-sig.
> In the future, this could be relaxed to include any template format that
> includes the file signature.
> 
> Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
> ---
>  security/integrity/ima/ima.h              | 3 ++-
>  security/integrity/ima/ima_api.c          | 3 ++-
>  security/integrity/ima/ima_appraise.c     | 3 ++-
>  security/integrity/ima/ima_main.c         | 7 ++++++-
>  security/integrity/ima/ima_template_lib.c | 3 ++-
>  5 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index be965a8715e4..ab257e404f8e 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -262,7 +262,8 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
>  int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
>  int ima_collect_measurement(struct integrity_iint_cache *iint,
>  			    struct file *file, void *buf, loff_t size,
> -			    enum hash_algo algo, struct modsig *modsig);
> +			    enum hash_algo algo, struct modsig *modsig,
> +			    bool veritysig);
>  void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
>  			   const unsigned char *filename,
>  			   struct evm_ima_xattr_data *xattr_value,
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> index 42c6ff7056e6..179c7f0364c2 100644
> --- a/security/integrity/ima/ima_api.c
> +++ b/security/integrity/ima/ima_api.c
> @@ -217,7 +217,8 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
>   */
>  int ima_collect_measurement(struct integrity_iint_cache *iint,
>  			    struct file *file, void *buf, loff_t size,
> -			    enum hash_algo algo, struct modsig *modsig)
> +			    enum hash_algo algo, struct modsig *modsig,
> +			    bool veritysig)

'veritysig' is being added here but it doesn't actually do anything.  It seems
this patchset is not split up correctly.

> +	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo,
> +				     NULL, FALSE);
>  	if (rc < 0)
>  		return;

false should be used instead of FALSE.

>  
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 465865412100..a73e1e845ea8 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -216,6 +216,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
>  	bool violation_check;
>  	enum hash_algo hash_algo;
>  	unsigned int allowed_algos = 0;
> +	int veritysig = FALSE;

Likewise.

> +	if (xattr_value && xattr_value->type == IMA_VERITY_DIGSIG &&
> +	    strcmp(template_desc->name, "ima-sig") == 0)
> +		veritysig = TRUE;

Likewise, true instead of TRUE.

- Eric