linux-kernel - Re: [PATCH] pstore: Fail to unlink if a driver has not defined pstore

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Message-ID: <CAGXu5jJpQJCc5OU6M-CvyvLAMyOOb=pxDMh586deYADxff23hQ@mail.gmail.com>
Date:	Mon, 24 Jun 2013 10:03:18 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Aruna Balakrishnaiah <aruna@...ux.vnet.ibm.com>
Cc:	Colin Cross <ccross@...roid.com>, Tony Luck <tony.luck@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Anton Vorontsov <cbouatmailru@...il.com>,
	jkenisto@...ux.vnet.ibm.com, benh@...nel.crashing.org,
	ananth@...ibm.com, mahesh@...ux.vnet.ibm.com
Subject: Re: [PATCH] pstore: Fail to unlink if a driver has not defined pstore_erase

On Mon, Jun 24, 2013 at 12:48 AM, Aruna Balakrishnaiah
<aruna@...ux.vnet.ibm.com> wrote:
> pstore_erase is used to erase the record from the persistent store.
> So if a driver has not defined pstore_erase callback return
> -EINVAL instead of unlinking a file as deleting the file without
> erasing its record in persistent store will give a wrong impression
> to customers.

This is probably true -- I originally liked the idea of being able to
clean up the entries, regardless of their storage state, but you're
probably right. They shouldn't be deleted unless they can _actually_
be deleted.

So, I support this change, but I think the return needs to be
different. EINVAL isn't listed, for example, in unlink(2)'s man-page.
Perhaps EROFS, EACCESS, or EPERM?

-Kees

>
> Signed-off-by: Aruna Balakrishnaiah <aruna@...ux.vnet.ibm.com>
> ---
>  fs/pstore/inode.c |    2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index e4bcb2c..fa6339a 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -178,6 +178,8 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry)
>         if (p->psi->erase)
>                 p->psi->erase(p->type, p->id, p->count,
>                               dentry->d_inode->i_ctime, p->psi);
> +       else
> +               return -EINVAL;
>
>         return simple_unlink(dir, dentry);
>  }
>



--
Kees Cook
Chrome OS Security
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