linux-kernel - Re: [PATCH] ovl: Prevent rw remount when it should be ro mount

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Date:	Fri, 02 Jan 2015 00:30:42 +0900
From:	Seunghun Lee <waydi1@...il.com>
To:	sedat.dilek@...il.com,
	Richard Weinberger <richard.weinberger@...il.com>
CC:	Miklos Szeredi <miklos@...redi.hu>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ovl: Prevent rw remount when it should be ro mount


On 01/02/2015 12:24 AM, Sedat Dilek wrote:
> On Thu, Jan 1, 2015 at 4:13 PM, Richard Weinberger
> <richard.weinberger@...il.com> wrote:
>> On Thu, Jan 1, 2015 at 6:07 AM, Seunghun Lee <waydi1@...il.com> wrote:
>>> Overlayfs should be mounted read-only when upper fs is r/o or nonexistend.
>>> But now it can be remounted read-write and this can causes kernel panic.
>>> So we should prevent read-write remount when the above situation.
>>>
>>> Signed-off-by: Seunghun Lee <waydi1@...il.com>
>> This patch makes zero sense, did you use the wrong diff?
>>
> Hmm, was also my 1st thoughts when I saw squashfs_remount() in overlayfs code.
>
> - Sedat -
>
>>> ---
>>>  fs/overlayfs/super.c | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
>>> index 84f3144..1faa5e5 100644
>>> --- a/fs/overlayfs/super.c
>>> +++ b/fs/overlayfs/super.c
>>> @@ -522,6 +522,14 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
>>>         return 0;
>>>  }
>>>
>>> +static int squashfs_remount(struct super_block *sb, int *flags, char *data)
>>> +{
>>> +       if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))
>>> +               *flags |= MS_RDONLY;
>>> +
>>> +       return 0;
>>> +}
>>> +
>>>  static const struct super_operations ovl_super_operations = {
>>>         .put_super      = ovl_put_super,
>>>         .statfs         = ovl_statfs,
>>> --
>>> 2.1.3
>>>
>>> --
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>>
>>
>> --
>> Thanks,
>> //richard
>> --
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Sorry, I sent wrong patch.

I will resend it.

Thanks.
--
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