linux-kernel - Re: [PATCH v2 6/7] ima: Discard files opened with O

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Message-ID: <906089e5f4e24182dc776488959dc595c92a616c.camel@linux.ibm.com>
Date: Thu, 16 Jan 2025 06:52:09 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Roberto Sassu <roberto.sassu@...weicloud.com>, viro@...iv.linux.org.uk,
        brauner@...nel.org, jack@...e.cz, dmitry.kasatkin@...il.com,
        eric.snowberg@...cle.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-security-module@...r.kernel.org,
        Roberto Sassu <roberto.sassu@...wei.com>, stable@...r.kernel.org
Subject: Re: [PATCH v2 6/7] ima: Discard files opened with O_PATH

On Thu, 2024-11-28 at 11:06 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.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@...r.kernel.org # v2.6.39.x
> Fixes: 1abf0c718f15a ("New kind of open files - "location only".")
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>

Thanks, Roberto.

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

Reviewed-by: Mimi Zohar <zohar@...ux.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