linux-kernel - Re: [PATCH] module: ban '.', '..' as module names, ban '/' in module names

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Date: Sun, 14 Apr 2024 13:58:55 -0700
From: Luis Chamberlain <mcgrof@...nel.org>
To: Alexey Dobriyan <adobriyan@...il.com>
Cc: akpm@...ux-foundation.org, linux-modules@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz
Subject: Re: [PATCH] module: ban '.', '..' as module names, ban '/' in module
 names

On Sun, Apr 14, 2024 at 10:05:05PM +0300, Alexey Dobriyan wrote:
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3616,4 +3616,12 @@ extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,
>  extern int generic_fadvise(struct file *file, loff_t offset, loff_t len,
>  			   int advice);
>  
> +/*
> + * Use this if data from userspace end up as directory/filename on
> + * some virtual filesystem.
> + */
> +static inline bool string_is_vfs_ready(const char *s)
> +{
> +	return strcmp(s, ".") != 0 && strcmp(s, "..") != 0 && !strchr(s, '/');
> +}
>  #endif /* _LINUX_FS_H */
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2893,6 +2893,11 @@ static int load_module(struct load_info *info, const char __user *uargs,
>  
>  	audit_log_kern_module(mod->name);
>  
> +	if (!string_is_vfs_ready(mod->name)) {
> +		err = -EINVAL;
> +		goto free_module;
> +	}
> +

Sensible change however to put string_is_vfs_ready() in include/linux/fs.h 
is a stretch if there really are no other users.

  Luis