linux-kernel - Re: [PATCH] security: inode: fix a missing check for securityfs_create

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Date:   Sat, 16 Mar 2019 07:34:32 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] security: inode: fix a missing check for
 securityfs_create_file

On 2019/03/16 6:00, Kangjie Lu wrote:
> securityfs_create_file  may fail. The fix checks its status and
> returns the error code upstream if it fails.

Failure in __init functions of vmlinux means that the system failed
before the global /sbin/init process starts. There is little value
with continuing the boot process. Calling panic() or BUG_ON() will
be OK, for the userspace will be get confused by lack of that file
even if we continued without securityfs entry in /proc/filesystems .

> 
> Signed-off-by: Kangjie Lu <kjlu@....edu>
> 
> ---
> Return the exact error code upstream.
> ---
>  security/inode.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/security/inode.c b/security/inode.c
> index b7772a9b315e..667f8b15027d 100644
> --- a/security/inode.c
> +++ b/security/inode.c
> @@ -339,6 +339,11 @@ static int __init securityfs_init(void)
>  #ifdef CONFIG_SECURITY
>  	lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL,
>  						&lsm_ops);
> +	if (IS_ERR(lsm_dentry)) {
> +		unregister_filesystem(&fs_type);
> +		sysfs_remove_mount_point(kernel_kobj, "security");
> +		return PTR_ERR(lsm_dentry);
> +	}
>  #endif
>  	return 0;
>  }
>