linux-kernel - Re: [PATCH v2 2/3] sysfs: Only accept read/write permissions for file attributes

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Date:	Wed, 11 Mar 2015 18:33:18 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	linux-kernel@...r.kernel.org, kernel@...oirfairelinux.com
Subject: Re: [PATCH v2 2/3] sysfs: Only accept read/write permissions for
 file attributes

On 03/11/2015 11:22 AM, Vivien Didelot wrote:
> For sysfs file attributes, only read and write permissions make sense.
> Mask provided attribute permissions accordingly and send a warning
> to the console if invalid permission bits are set.
>
> This patch is originally from Guenter [1] and includes the fixup
> explained in the thread, that is printing permissions in octal format
> and limiting the scope of attributes to SYSFS_PREALLOC | 0664.
>
> [1] https://lkml.org/lkml/2015/1/19/599
>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>   fs/sysfs/group.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index 3fdccd9..b400c04 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -55,6 +55,12 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
>   				if (!mode)
>   					continue;
>   			}
> +
> +			WARN(mode & ~(SYSFS_PREALLOC | 0664),
> +			     "Attribute %s: Invalid permissions 0%o\n",
> +			     (*attr)->name, mode);
> +
> +			mode &= SYSFS_PREALLOC | 0664;
>   			error = sysfs_add_file_mode_ns(parent, *attr, false,
>   						       mode, NULL);
>   			if (unlikely(error))
>

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