Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.33 as permitted sender) client-ip=23.128.96.33;
Message-ID: <980b8df5eccc03a67328e28b7cef2b777bc310f0.camel@linux.ibm.com>
Subject: Re: [PATCH v4 12/23] security: Introduce file_post_open hook
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Roberto Sassu <roberto.sassu@huaweicloud.com>,
        viro@zeniv.linux.org.uk, brauner@kernel.org,
        chuck.lever@oracle.com, jlayton@kernel.org, neilb@suse.de,
        kolga@netapp.com, Dai.Ngo@oracle.com, tom@talpey.com,
        paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com,
        dmitry.kasatkin@gmail.com, dhowells@redhat.com, jarkko@kernel.org,
        stephen.smalley.work@gmail.com, eparis@parisplace.org,
        casey@schaufler-ca.com, mic@digikod.net
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nfs@vger.kernel.org, linux-security-module@vger.kernel.org,
        linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
        selinux@vger.kernel.org, Roberto Sassu <roberto.sassu@huawei.com>,
        Stefan Berger <stefanb@linux.ibm.com>
Date:   Mon, 06 Nov 2023 11:40:08 -0500
In-Reply-To: <20231027083558.484911-13-roberto.sassu@huaweicloud.com>
References: <20231027083558.484911-1-roberto.sassu@huaweicloud.com>
         <20231027083558.484911-13-roberto.sassu@huaweicloud.com>
Content-Type: text/plain; charset="ISO-8859-15"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Fri, 2023-10-27 at 10:35 +0200, Roberto Sassu wrote:
> diff --git a/security/security.c b/security/security.c
> index 2ee958afaf40..d24a8f92d641 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2947,6 +2947,23 @@ int security_file_open(struct file *file)
>         return fsnotify_perm(file, MAY_OPEN);
>  }
>  
> +/**
> + * security_file_post_open() - Recheck access to a file after it has been opened
> + * @file: the file
> + * @mask: access mask
> + *
> + * Recheck access with mask after the file has been opened. The hook is useful
> + * for LSMs that require the file content to be available in order to make
> + * decisions.
> + *

The hook isn't limited to "Recheck access".    It's used for measuring,
appraising, and auditing a file's integrity.   Sorry for suggesting an
incomplete patch description.  Please update the wording here and the
patch description accordingly.

> + * Return: Returns 0 if permission is granted.
> + */
> +int security_file_post_open(struct file *file, int mask)
> +{
> +       return call_int_hook(file_post_open, 0, file, mask);
> +}
> +EXPORT_SYMBOL_GPL(security_file_post_open);
> +
>  /**
>   * security_file_truncate() - Check if truncating a file is allowed
>   * @file: file

-- 
thanks,

Mimi