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

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Date:	Thu, 1 Jan 2015 16:24:53 +0100
From:	Sedat Dilek <sedat.dilek@...il.com>
To:	Richard Weinberger <richard.weinberger@...il.com>
Cc:	Seunghun Lee <waydi1@...il.com>,
	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 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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