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Re: [RFC][PATCH 3/7] smack: assign the label set in file->f_cred to new file descriptors

To: Roberto Sassu <roberto.sassu@xxxxxxxxx>
From: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Date: Wed, 27 Apr 2011 16:26:43 -0700
Cc: kirkland@xxxxxxxxxxxxx, safford@xxxxxxxxxxxxxx, sds@xxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, eparis@xxxxxxxxxx, jmorris@xxxxxxxxx, dhowells@xxxxxxxxxx, linux-security-module@xxxxxxxxxxxxxxx, viro@xxxxxxxxxxxxxxxxxx, selinux@xxxxxxxxxxxxx, ecryptfs-devel@xxxxxxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, zohar@xxxxxxxxxxxxxxxxxx
In-reply-to: <1303907657-18366-4-git-send-email-roberto.sassu@polito.it>
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9

On 4/27/2011 5:34 AM, Roberto Sassu wrote:
> The SMACK label of new file descriptors is obtained from the credentials
> set in the 'f_cred' field of the same structure.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxx>
> ---
>  security/smack/smack_lsm.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index c6f8fca..e3c9e54 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -1011,7 +1011,7 @@ static int smack_file_permission(struct file *file, int mask)
>   */
>  static int smack_file_alloc_security(struct file *file)
>  {
> -	file->f_security = smk_of_current();
> +	file->f_security = smk_of_task(file->f_cred->security);

Now hang on. This just looks wrong. You're setting the value of one
field of the file structure to another value in the same file structure.
I don't see that this is what I want.

>  	return 0;
>  }
>