linux-kernel - Re: [PATCH] fuse: Send FUSE_WRITE_KILL

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Date:   Mon, 21 Jun 2021 08:54:33 -0500
From:   Connor Kuehl <ckuehl@...hat.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fuse: Send FUSE_WRITE_KILL_SUIDGID for killpriv v1

On 6/21/21 3:26 AM, Miklos Szeredi wrote:
> On Fri, 23 Apr 2021 at 17:19, Connor Kuehl <ckuehl@...hat.com> wrote:
>>
>> FUSE doesn't seem to be adding the FUSE_WRITE_KILL_SUIDGID flag on write
>> requests for FUSE connections that support FUSE_HANDLE_KILLPRIV but not
>> FUSE_HANDLE_KILLPRIV_V2.
>>
>> However, the FUSE userspace header states:
>>
>>         FUSE_HANDLE_KILLPRIV: fs handles killing suid/sgid/cap on
>>         write/chown/trunc
>>         ^^^^^
>>
>> To improve backwards compatibility with file servers that don't support
>> FUSE_HANDLE_KILLPRIV_V2, add the FUSE_WRITE_KILL_SUIDGID flag to write
>> requests if FUSE_HANDLE_KILLPRIV has been negotiated -OR- if the
>> conditions for FUSE_HANDLE_KILLPRIV_V2 support are met.
> 
> 
> If server does not support FUSE_HANDLE_KILLPRIV_V2, then it does not
> support FUSE_WRITE_KILL_SUIDGID either.  The two were introduced
> together and the latter is only meaningful if the
> FUSE_HANDLE_KILLPRIV_V2 feature was negotiated.
> 
> What am I missing?

You're not missing anything, this patch is wrong. Let's nack this.

Thanks!

Connor