[PATCH v4 12/23] security: Introduce file_post_open hook

[Mimi Zohar]

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