Re: [PATCH v2 6/7] ima: Discard files opened with O_PATH

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

On Thu, 2024-11-28 at 11:06 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
> 
> According to man open.2, files opened with O_PATH are not really opened. The
> obtained file descriptor is used to indicate a location in the filesystem
> tree and to perform operations that act purely at the file descriptor
> level.
> 
> Thus, ignore open() syscalls with O_PATH, since IMA cares about file data.
> 
> Cc: stable@vger.kernel.org # v2.6.39.x
> Fixes: 1abf0c718f15a ("New kind of open files - "location only".")
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>

Thanks, Roberto.

Note: Ignoring open() with O_PATH impacts policies containing "func=FILE_CHECK"
rules.

Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

> ---
>  security/integrity/ima/ima_main.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 50b37420ea2c..712c3a522e6c 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -202,7 +202,8 @@ static void ima_file_free(struct file *file)
>  	struct inode *inode = file_inode(file);
>  	struct ima_iint_cache *iint;
>  
> -	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
> +	if (!ima_policy_flag || !S_ISREG(inode->i_mode) ||
> +	    (file->f_flags & O_PATH))
>  		return;
>  
>  	iint = ima_iint_find(inode);
> @@ -232,7 +233,8 @@ static int process_measurement(struct file *file, const struct
> cred *cred,
>  	enum hash_algo hash_algo;
>  	unsigned int allowed_algos = 0;
>  
> -	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
> +	if (!ima_policy_flag || !S_ISREG(inode->i_mode) ||
> +	    (file->f_flags & O_PATH))
>  		return 0;
>  
>  	/* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action