linux-kernel - Re: [PATCH] sysfs: sysfs_sd_setattr set iattrs unconditionally

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Date:	Thu, 11 Feb 2010 07:33:29 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Greg KH <gregkh@...e.de>
Cc:	Jean Delvare <khali@...ux-fr.org>,
	LKML <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
	Serge Hallyn <serue@...ibm.com>
Subject: Re: [PATCH] sysfs: sysfs_sd_setattr set iattrs unconditionally


Greg I think this patch has slipped through the cracks.
Do I need to resend this regression fix or send it directly to Linus?

chmod and friends have been broken on sysfs since 2.6.32...

Eric

ebiederm@...ssion.com (Eric W. Biederman) writes:

> There is currently a bug in sysfs_sd_setattr inherited from
> sysfs_setattr in 2.6.32 where the first time we set the attributes
> on a sysfs file we allocate backing store but do not set the
> backing store attributes.  Resulting in overly restrictive
> permissions on sysfs files.
>
> The fix is to simply modify the code so that it always executes
> when we update the sysfs attributes, as we did in 2.6.31 and earlier.
>
> Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
> ---
>  fs/sysfs/inode.c |   35 +++++++++++++++++------------------
>  1 files changed, 17 insertions(+), 18 deletions(-)
>
> diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
> index 220b758..6a06a1d 100644
> --- a/fs/sysfs/inode.c
> +++ b/fs/sysfs/inode.c
> @@ -81,24 +81,23 @@ int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
>  		if (!sd_attrs)
>  			return -ENOMEM;
>  		sd->s_iattr = sd_attrs;
> -	} else {
> -		/* attributes were changed at least once in past */
> -		iattrs = &sd_attrs->ia_iattr;
> -
> -		if (ia_valid & ATTR_UID)
> -			iattrs->ia_uid = iattr->ia_uid;
> -		if (ia_valid & ATTR_GID)
> -			iattrs->ia_gid = iattr->ia_gid;
> -		if (ia_valid & ATTR_ATIME)
> -			iattrs->ia_atime = iattr->ia_atime;
> -		if (ia_valid & ATTR_MTIME)
> -			iattrs->ia_mtime = iattr->ia_mtime;
> -		if (ia_valid & ATTR_CTIME)
> -			iattrs->ia_ctime = iattr->ia_ctime;
> -		if (ia_valid & ATTR_MODE) {
> -			umode_t mode = iattr->ia_mode;
> -			iattrs->ia_mode = sd->s_mode = mode;
> -		}
> +	}
> +	/* attributes were changed at least once in past */
> +	iattrs = &sd_attrs->ia_iattr;
> +
> +	if (ia_valid & ATTR_UID)
> +		iattrs->ia_uid = iattr->ia_uid;
> +	if (ia_valid & ATTR_GID)
> +		iattrs->ia_gid = iattr->ia_gid;
> +	if (ia_valid & ATTR_ATIME)
> +		iattrs->ia_atime = iattr->ia_atime;
> +	if (ia_valid & ATTR_MTIME)
> +		iattrs->ia_mtime = iattr->ia_mtime;
> +	if (ia_valid & ATTR_CTIME)
> +		iattrs->ia_ctime = iattr->ia_ctime;
> +	if (ia_valid & ATTR_MODE) {
> +		umode_t mode = iattr->ia_mode;
> +		iattrs->ia_mode = sd->s_mode = mode;
>  	}
>  	return 0;
>  }
> -- 
> 1.6.5.2.143.g8cc62
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